Inspection, Alignment, Cementing and Assembly of Optics

OptiCentric®

Inspection, Alignment, Cementing and Assembly of Optics

OVERVIEW

2

Page

Principle of the Centering Error Measurement in Reflection and Transmission Mode . . . . . . . . . . 4

Centering Errors of Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

OptiCentric® MAN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

OptiCentric® SMART . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

OptiCentric® MOT 100 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12

OptiCentric® MOT 300 UltraStable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

OptiCentric® MAX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16

OptiCentric® Custom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17

OptiCentric® Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18

OptiCentric® MOT Extension Modules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Automated Cementing of Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Automated Bonding of Lenses into a Mount . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Lathe Centering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

OptiCentric® Cementing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

OptiCentric® Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

OptiCentric® Lathe Centering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30

Motorised Centering and Cementing Equipment with Vacuum Chuck . . . . . . . . . . . . . . . . . . .31

Extension of Measurement Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31

Measuring Sensor and Linear Measuring Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Alignment Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Illumination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Revolving Turret . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

Calibration Tool . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32

OptiCentr ic® PRO for Product ion 28

Assembly of Opt ics 25

Accessories 31

Application Overview 33

Overview of Available Conf igurations 34

Order Information 35

OptiCentr ic® METRO for Metrology 8

Measurement of Centering Errors 4

OptiCentr ic® 3

OptiCentric®

3

According to ISO 10110 a centering error ispresent when the optical and the referenceaxis of a lens do not coincide, respectivelythese are different in position or direction.

During the process of cementing, alignmentand bonding of lenses in a mount, significantcentering errors can result and add to themachining errors of a lens. Consequently, therequirements of a high performance opticalsystem can only be fulfilled when all the pro-duction steps from the centering tolerancemeasurement to the assembly of the lens in amount are planned and designed as an inte-grated concept.

The TRIOPTICS comprehensive line of equip-ment under the generic name OptiCentric®

has been specifically designed to cover ap-plications related to any type of optical com-ponents and to respond to different accuracydegrees. The OptiCentric®-System also coversall the production steps from the centrationmeasurement to the alignment, cementingand assembly of optics. The OptiCentric® in-cludes valuable tools for any application,from simple and affordable visual instrumentsto complex, fully automated and PC-con-trolled production and laboratory stations.

The modular TRIOPTICS product group is ableto measure nearly all types of lenses and opti-cal systems from the tiniest and smallest en-doscope systems to precision objectivesweighting several hundred kilos for wafer step-pers in the semiconductors industry.

The products of the OptiCentric® range aresubdivided into:

• OptiCentric® METRO - for Metrology and comprehensive measurement of optical systems

• OptiCentric® PRO - for Production and As- sembly of objective lenses

The capabilities of OptiCentric® METRO arenot limited to the measurement of lens cen-tration errors. Various enhancements and ad-ditional modules allow for measurement ofmany other optical parameters to be pre-sented in the next chapters.

OptiCentric®

OptiCentric® Measurement tool for miniature lenses

MEASUREMENT OF CENTERING ERRORS

4

The following sections describe the measure-ment principle behind the OptiCentric® instru-ments and typical errors which occur duringthe assembly of lenses and objectives. Themeasurement of a centering error primarily in-volves defining a point of symmetry in relationto a reference axis. This can, for example, bethe center of curvature of a lens surface orthe location of a focus point of a lens in rela-tion to a reference axis. When the center ofcurvature of a lens surfaces is used for mea-surement of centration errors, the measuringprocedure is known as “Reflection Mode”.Similarly the measuring procedure using thefocal point of a lens is known as “TransmissionMode”

Principle of the Centering Error Measure-ment in Reflection and Transmission Mode

The basic procedure to identify the centeringerrors of a lens implies the rotation of the lensaround a precise reference axis. The precisereference axis is decisive for the accuracy ofthe measurement. The OptiCentric® productline provides different instrument modules oraccessories featuring an extreme accuratereference axis for the measurement.

For the measurement, an autocollimator withadditional optics is focussed either in the cen-ter of curvature of the surface (ReflectionMode) or in the focal plane of the lens (Trans-mission Mode). For the measurement in trans-mission a collimator is additionally needed.The parallel beam emerging from the colli-mator is focussed in the focal plane of thesample to be measured.

The images reflected from the lens surfaces(Reflection method) as well as the imagesprojected into the focus of the lens (Transmis-

sion Method) are observed through the eye-piece of an autocollimator of a telescope orof a microscope.

In the modern instruments the autocollimatoris equipped with a CCD-Camera and the en-tire measurement process is controlled by thesoftware.

When a centration error is present, the ob-served image describes a circle while thesample is rotated around a reference or da-tum axis. When using software programs therotation of center of curvature can be fol-lowed directly on the monitor. The live reticuleimage shows the exact position of the centerof curvature in the x-y plane, whereby thecenter of the circular path represents the ref-erence axis.

The radius or the diameter of the circle is pro-portional to the size of the centring errors. Theresult of the measurement can be given asradius of the run out circle (in µm) or as tilt ofthe surface or of the lens axis (in arcsec).

Measurement of Centering Errors

Lens rotation device with Vacuum Chuck


5

Comparison between Reflection and Trans-mission Mode

Transmission and reflection measurements es-sentially provide different results. The reflectionmeasurement will provide exact informationon the centering error of single surfaces, whilethe transmission measurement provides an“overall error” which is a combined result ofthe centering errors of all the single surfaces.

In transmission mode it is not possible to de-termine which one of the two surfaces of alens is producing the centration error. In somecases, a lens tested in transmission modecan reveal no centering error, although thelens is tilted in the mount.

The images reflected from the lens surfaces,however represent an undoubted criterion forthe surface tilt and the individual centring er-rors. The reflection method is the only totaland true method for the measurement ofcentration errors. However, the reflectionmethod is in many cases difficult to manage.On the other hand, the transmission methodwith some mechanical constraints gives inmany cases satisfactory results. For a goodeconomy of the optical manufacturing bothmethods should be considered. OptiCentric®

allows both methods to be used.

The reflection and the transmission values aretherefore different and may only be com-pared to a limited extent. A simple relation-ship between the two measurements for thecentering error of a single lens only (without amount) can be given by:

T = (n - 1) R

R: Surface tilt error of top surface (Result ofmeasurement in reflection mode)T: Angle deviation in transmission moden: Refractive Index of glass

Centering Errors of Lenses

Centering errors have a decisive influenceon the optical imaging quality of an imagingsystem. A centering error is present if the axisof symmetry of an optical element does notcoincide with a given reference axis. The ref-erence axis is typically the symmetry axis of amount or cell. The centering error is given asan angle between the optical axis of this ele-ment and the reference axis. A centering er-ror may also be given as the distance be-tween, for example, a center of curvatureand another reference point on the referenceaxis.

Fig. 2: Measurement in Transmission Mode

CCD

Camera Adapter

Autocollimatorwith additionalachromat

Measuring Centrationin Transmission Mode

Ultra-precisionrotary holder

Collimator Cross Reticle

Mirror

Fig.1: Measurement in Reflection Mode

Camera Adapter

Autocollimatorwith additionalachromat

Measuring Centrationin Reflection Mode

Ultra-precisionrotary holder

IlluminatedBright crossCCD

function, systems have been de-veloped to carry out the preciseassembly of optical systems asan extension of the OptiCentric®

system.

The Centering Error of a Spheri-cal Surface

The centering error of a spheri-cal surface is defined by thedistance “a„ of its center of cur-vature “C1„ to a reference axis.The surface tilt error χ may alsobe used.

The following correlation applies(r = radius of the surface undertest):

χ = arcsin (a/r) [rad]

χD = 3438 χ [arc minutes]χD = angle of the centering error in

arc minutes

It is also possible to provide the measured sur-face tilt error as eccentricity S at the lensedge if required. (Fig. 5)

S = D✕ tan(χ)

D = lens diameter


6

Fig. 3 provides an overview of the typicalcentering errors.

1. Translational displacement of a lens2. Tilt of a lens3. Surface tilt error of a spherical surface4. Cementing error5. Tilt of the aspherical axis

OptiCentric® is able to define precisely all ofthese errors in accordance with ISO 10110-6.OptiCentric® features capabilities for measur-ing single lenses, surface tilt and cementingerror or for the measurement of complete ob-jectives. The so-called MultiLens® procedureenables the measurement of the centering er-ror of all single surfaces of a fully assembledobjective without the need to dismantle it.Building on this comprehensive measurement

Fig. 4: Schematic diagram of the surface tilt error

Axis perpendicular to

the upper surface

Centre of curvature

C1

χ

χ a

Fig. 3: Typical centering errors

➀

➂

➃

➄

➁


7

The Centering Error of a Lens

The optical axis of a single lens (see figure 6,left side) is the line connecting the centers ofcurvature of the two spherical surfaces. Thecentering error is now defined using the angle„χ“ and the distance „a“ to a given referenceaxis.

If only a single lens is being defined, then therelationship between the centering error andthe processing of the lens edge is important.In this instance, the reference axis used is aline through one of the centers of curvatureand the center of the diameter (see figure 6right side). The surface tilt error of the secondsurface is given in relation to this tilt axis. Thiserror is also known as the wedge error of alens.

Centering Errors of Aspherical Lenses

In contrast to spheres, defined by a center ofcurvature, aspherical surfaces have an axis ofsymmetry. Therefore, in order to define a cen-tering error at least one distance informationis required in addition to an angle.

The angle is defined by the angle betweenthe aspherical axis and the reference axis.The distance may only be defined for onespecific reference point on the reference axis.This could be the center of curvature in theparaxial area of the asphere, for example.

Fig. 5: Surface tilt error given as eccentricity

D

S

Fig. 6: Schematic diagram of the centering error of a lens

Center of Diameter with

respect to the edge

Reference axis

C1

C2

χ

χ

Reference axis

Optical axis of the

individual lens

C1

a

C2

χ

OptiCentric® METRO

8

The following parameters are measured bythe OptiCentric® program:

1) Shift and tilt of the asphere axis in relation to the reference axis of rotation.

2) Shift and tilt of the asphere axis in relation to the optical axis of the lens. The “optical axis” is considered to be the line running through the centers of curvatures of the spherical portions.

3) When a lens consists of two aspherical sur-faces the angle and shift of both asphericalaxes are determined.

Centering Errors of Cylindrical Lenses

A cylindrical surface has an axis of symmetry,called the cylinder axis. There are differentcentering errors related to the cylinder axis.

1) Angle between the cylinder axis and the edge of the lens

2) Offset of the cylinder axis to the edge of the lens.

3) Angle between the cylinder axis and the plane surface of the lens.

The OptiCentric® system is also able to definethe centering error of the cylinder axis in as-sembled anamorphic objectives.

Centering Errors of Optical Surfaces within anAssembled Objective

In order to measure single optical surfaces,the exact tilt error and/or exact position of thecenter of curvature to a given reference axishas to be determined. Influences from opti-cal surfaces and elements located beforethe surface under test are taken into accountusing optical calculations including the cen-tering error of these surfaces. That means thatthe centering error of all further surfaces mustbe iterated from that of the first.

Approx. 20 surfaces can be measured fromone side using this method. If a second mea-suring head is used, such as in the OptiCen-tric® MOT Dual, which calculates the center-

ing error from the bottom side, up to 40 ormore optical surfaces can be measured.

For this application a special software moduleMultiLens® has been developed. The Multi-Lens® measurement provides the exact x,y,zco-ordinates of all centers of curvature in thespace. The measured data support furtheranalysis of the lens system and provide addi-tionally the following data:

• Calculation of the optical axis of any single lens of the system.

• Assessment of the optical axis of single sub-systems or the entire optical system. A „bestfit“ line is drawn through all the optical sur-faces under consideration.

OptiCentric® METRO instruments are designedto measure centering errors and other para-meter of lenses and optical systems. All instru-ments of METRO Series can be used to carryout measurements using the reflection modeand/or transmission mode, an exception be-ing the OptiCentric® SMART which only worksin reflection mode.

OptiCentric® METRO is of modular design, sothat the instruments are upgradeable andcompatible with each other. To make the se-lection of the suitable equipment easier, in afirst step the main instrument parts are pre-sented.

Optical Measuring Head

The optical measuring head of the instru-ment is designed to view and quantify thesize of the centering error in single and multi-ple optical components. It is also the basicunit used for alignment of single elements be-fore cementing or mounting in cells.

This is usually an autocollimator equipped withadditional head lenses which is focussed in

OptiCentric® METRO

OptiCentric® METRO

9

the image plane of the sample (transmissionmethod) or in the centre of curvature of thelens surface under test (reflection method).

Stands with Travel Mechanism or MotorizedStages

The optical measuring head is mounted on astand having capabilities to move up anddown in order to adapt to a certain range ofradii of curvature (for Reflection Mode) or offocal length (for Transmission Mode).

Sample Holder

Depending on applications OptiCentric®

METRO provides a large variety of sampleholders: self-centering holders, vacuum reten-tion devices, hydrostatic chucks, three jawschucks, etc.

Lens Rotation Devices

Since the viewing and the measurement ofthe centering errors are only possible whenthe lens is rotated (except for extremely ex-pensive errorless focusing devices), the avail-ability of a lens holding and rotary device iscrucial for completing a centering measure-ment.

The accuracy of the centering measurementand of the alignment/mounting of lenses isdetermined by the two basic components ofa centering/mounting equipment:

• Optical measuring head • Lens Rotation Device

Many optics manufacturers underestimatethe importance of the Lens Rotation devicesin ensuring the required accuracy. Since theuse of accurate CCD-cameras and compleximage processing software provides a highaccuracy of optical measuring heads, thelargest error source in lens centring andmounting is in many cases the Lens RotationDevice. Many of the Lens Rotation Devicesused in the optical manufacturing do not pro-vide a reference rotation axis which is enoughaccurate and stable.

TRIOPTICS invested a large amount of work indesigning a complete range of accurate de-vices for lens rotation:

• Motorized Vacuum-Lens Rotation Device• Ultra-Precision Air Bearing Rotary Table• Mechanical and Hydrostatic Lens Holders

OptiCentric® MAN

OptiCentric® MAN stands for the manual op-eration of the stage with fine coaxial heightadjustments. This is a simple and cost effec-tive solution, although the time needed tomove the measuring head up and down re-duces the efficiency of the process. More-

Fig. 7: Principle setup OptiCentric®

1. Autocollimator with CCD-Camera

2. Additional Achromat in X-,Y- adj.Mount

3. Sample

4. Mirror

5. Collimator

6. Lens rotation device

OptiCentric® METRO

10

over, the travel is limited, since the height ofthe stand must be selected so that the oper-ator works in a seated position. Consequently,to cover a certain range of radii/focal lengthan increased number of additional optics isnecessary.

This product line is the right choice when thenumber of surfaces to be measured is limitedor the instrument is used for repetitive mea-surements of the same lens type. Examples oftypical applications for OptiCentric® MAN arethe centering error measurement of singlelenses or alignment and cementing of dou-blets.

An important accessory of the OptiCentric®

MAN instruments is the motorized vacuum-lens rotation unit which can also be used formeasurement or cementing of doublets.

OptiCentric® MAN has two manual stand op-tions:

• Stand “B” with 250 mm travel• Stage “BL” with 400 mm travel

In order to easily find the height position of dif-ferent centers of curvature or focal planes ofthe samples to be measured, the manualstand should be additionally equipped withlinear encoders displaying the position of themeasuring head on the stand. For OptiCen-tric® MAN position measuring devices includ-ing a linear slide with LCD-Display, 0.01 mmresolution and 300/450 mm length are avail-able.

The OptiCentric® MAN instruments may be fit-ted with different measuring heads depend-ing on application and accuracy required.Following basic options are available:

OptiCentric® MAN with accessories

OptiCentric® METRO

11

• Visual measuring head (OptiCentric® MAN-Visual)

• Measuring head with CCD camera and video-monitor (OptiCentric® MAN-Video)

• Measuring head with CCD camera, PC andsoftware control (OptiCentric® MAN)

OptiCentric® MAN-Visual

The operator reads the centering error off areticule (e.g. with mill imeter graduation)through the eye piece of the autocollimator.The purely visual check is simple and there-fore a cost-effective solution although accu-racy and reproducibility are restricted. Themeasurement result depends on the skills andlevel of fatigue of the operator. The OptiCentric® MAN-Visual is suitable formeasuring and cementing individual lenseswhere the measurement does not require ahigh degree of accuracy or speed.

OptiCentric® MAN-Video

The measuring head consists of a CCD-cam-era and imaging optics mounted on the eye-piece. The CCD-Camera is connected to aVideo-Monitor, the centering error can nowbe read on the monitor. This product versionincreases the comfort in operation, allows theoperator to better concentrate on the rotationof sample, however, has the same limitationconcerning the accuracy and repeatablity

Neither OptiCentric® MAN-Visual nor OptiCen-tric® MAN-Video provides records of the cen-tering errors or of the accuracy achieved. Thisis an important drawback of these productversions especially when it comes to integra-tion in modern quality assurance systems.

OptiCentric® MAN

The use of an automated, PC-controlled op-tical measuring head increases dramaticallythe accuracy and repeatability, providesrecords of the tolerances achieved and is notdependent on the skills or the level of fatigueof the operator. The CCD-camera is in thiscase either connected to a frame grabber or

to a digital interface card mounted in the PC.The software controls the measuring process,so that the accuracy and repeatability of themeasurement and the stability of the processare significantly increased.

The measurement data are automaticallyacquired and used for calculation of center-ing errors or utilized for further complex analy-sis.

The measuring certificate includes data pre-sented according to the standard ISO 10110,so that a direct comparison with the toler-ance values is possible.

OptiCentric® SMART

The conceptual design of OptiCentric®

SMART is made to measure large quantities ofthe same type of single lenses in reflection.However OptiCentric® SMART can be used aswell for the cementing of lenses.

OptiCentric® SMART

OptiCentric® METRO

12

OptiCentric® SMART is a cost-effective com-pact test station with an electronic measuringhead and a motorized axis for focusing themeasuring head. All the essential functionsare integral to the standard instrument. Thehigh-power LED illumination and control areintegrated in the measuring head. The elec-tronic autocollimator has an effective focallength of 150 mm and a slightly reduced res-olution compared to the autocollimatorsused in OptiCentric® MOT.

OptiCentric® SMART is available with both ver-sions of the vacuum lens rotation device andis ideal for investigating the centering errors ofsingle lenses and for cementing doublets ortriplets in a production environment. The travelof the motorized focusing stage is 250 mm.The centering error measurement is accurateto 0.2 µm.

The standard OptiCentric® SMART comes witha single measuring head. As an option it ispossible to mount a second measuring headunderneath the sample on the base of the in-strument. This measuring head enables the si-multaneous measurement of the bottom sur-face of the sample. However, the optional at-tachment only has a manual focus range of+/- 10 mm. Due to the short focusing range alarge range of head lenses is neccessary. Thecontrol and analysis of the instrument is car-ried out using the standard OptiCentric® soft-ware.

OptiCentric® MOT 100

OptiCentric® MOT 100 is the heart of the Op-tiCentric® system being used in a wide rangeof applications, either fulfilling complex mea-surement tasks or accomplishing importantsteps in the assembly and production processof optical systems. Recognized as industry’sstandard for centering error measurement,OptiCentric® MOT 100 provides outstandingaccuracy and flexibility covering applicationsfrom tiny endoscope and mobile phone lens-es to precision digital camera lenses.

OptiCentric® MOT 100 is PC-controlled andequipped with an accurate stepper motorstage for positioning or focusing of the mea-suring head. The measuring head can beprogrammed to drive to several focus posi-tions or centers of curvature of multi elementlenses. The setup data containing the posi-tions of centers of curvatures, radii and otherdesign data can be saved to a file andloaded for any future measurements oranalysis. In this way the centering error mea-surement, alignment and assembly of multi-element lenses becomes an efficient and re-liable production process.

The measuring head includes a precisionelectronic autocollimator achieving an accu-racy of 0.1 µm when measuring centering er-rors. In addition all instruments belonging toOptiCentric® MOT 100 can be equipped withan autocollimator with a longer effective fo-cal length or a CCD camera with a higherresolution thus further increasing the accuracy

OptiCentric® MOT 100, AB 100 air bearing

OptiCentric® MOT 100 with air bearing AB 100 andTRT200 tilt and translation table

OptiCentric® METRO

13

and reliability of the measurements.For applications requiring highest accuracy,OptiCentric® MOT 100 can be equipped withan ultra-precision rotary air bearing table. Therotary air bearing provides lens rotation facili-ties and an ultra-stable and ultra-accuratereference (rotation) axis for measurement ofcentering errors. For alignment needs the airbearing is equipped with a stable tilt andtranslation stage (see left page).

The air bearing integrated in OptiCentric®

MOT 100 is specially designed for optical ap-plications requiring outstanding accuracyand stiffness (axial and radial errors of lessthan 0.05 μm). Typical example is the assem-bly of high performance multi-lens objectives.The air bearing features a central hole for

measuring in transmission mode or for check-ing the lens surfaces in reflection mode inconnection with the dual measuring head.The precision rotation motor provides smoothrotation - without any vibrations - and, if nec-essary, accurate angular positioning. For along operational life, the air bearings are sup-plied with a complete air conditioning controlunit including a membrane dryer, filter andmanometer.

The TRT 200 tilt and translation table belongsto the air bearing and is used for aligning thesample or the sample holder. OptiCentric®

MOT 100 systems are fitted with an AB100 airbearing which has an external diameter of120 mm and a maximum load capacity of20 kg.

OptiCentric® MOT 100 with air bearing and accessories

OptiCentric® METRO

14

OptiCentr ic® MOT100 - Single Head

The standard instru-ment includes ameasuring headconsisting of an elec -tronic autocollimatormoun t ed on a mo-torized linear stage.The travel of the stan-dard measuringhead is 450 mm. Ver-sions with a travel of250 and 550 mmare also available.The l inear stage ismounted on thebase of the instru-ment. This base con-tains a collimator formeasuring transmission. The light of the hori-zontally mounted collimator is reflected by a45 dregree deflection mirror through the sam-ple under test.

The measuring head can be moved to anynumber of previously saved focal points orcenters of curvature. This enables the fast andeasy alignment and assembly of multi-lensobjectives. The OptiCentric® MOT 100 is suit-able for automated measurement process.

In addition to taking centering error measure-ments the instrument can also be upgradedto measure radius of curvature or can also beupgraded to measure effective focal length,flange focal length and axial MTF.

OptiCentric® MOT 100 - Dual Head

For the alignment and assembly of complexand multi-lens objectives, TRIOPTICS devel-oped a dual head instrument series allowingthe simultaneous alignment and measure-ment of bottom and upper lens surfaces.Thus it is possible to determine and correct inreal time the centering errors of two optical

surfaces in both the x and y axis after just onerotation. This proprietary design improves dra-matically the capabilities of the instrument inthe field of lens assembly and measurementof centering errors. The dual head is particu-larly efficient at measuring multiple lenses inorder to determine the centering errors withinan assembled optical system. The travel ofthe lower axis is limited to 250 mm due to the

height of the instrument.Extended Sample Diameter

The maximum diameter of a sample handledby the OptiCentric® MOT range is determinedby the distance between the center of the ro-tation axis and the linear stage. The standard systems presented here handlea sample with a maximum diameter of 225mm. The diameter range may be increasedby enlarging the distance between the rota-

OptiCentric® MOT 100 Dual Head

OptiCentric® MOT 100 withrevolving turret

OptiCentric® METRO

15

tion axis and column with the linear stage. OptiCentric® MOT 300 UltraStable

The OptiCentric® MOT 300 UltraStable rangeprovides solid and stable instrument frames,anti-vibration isolators, heavy duty air bearingsand rigid translation and tilt stages. The heavyduty air bearings have a diameter of 300mm, extremely high stiffness, and axial andradial errors significantly lower than 80 nm.

The OptiCentric® MOT 300 UltraStable hasbeen further developed to cover special ap-plications in the aviation and space industry,military and astronomy. The OptiCentric® MOT300 Ultra Stable is able to support samples upto 2 meters in height and 300 kg in weight.The motorized focusing stage of 450 mmtravel can be moved manually up to two me-ters in height in order to accomodate larger

samples.When the pre-alignment of the lens chuck orlens cell is accurately made, the ultra-preci-sion air bearing table gives the highest possi-ble accuracy for assembly, cementing orbonding of lenses in barrels. Using the ultra-stable and finely adjustable tilt and translationtables, not only tiny changes in tilt as small as1 arcsec are achievable, but also the assem-bly of heavy, large objectives is possible.

OptiCentric® MOT 300 UltraStable under production

Air bearing OptiCentric® MOT 300 UltraStable with tiltand TRT 400 translation stage

OptiCentric® METRO

16

OptiCentric® MOT 300 - Sin-gle Head

This measuring head can al-so be moved to any numberof previously saved focalpoints or centers of curva-ture (see as well single headOptiCentric® MOT 100). Thisenables the alignment andassembly of multi-lens ob-jectives. The OptiCentric®

MOT UltraStable is capableof a highly automated mea-surement process. It is possi-ble to use this system to car-ry out all measurement andalignment tasks which canalso be undertaken using theOptiCentric® MOT 100.

OptiCentric® MOT 300 - DualHead

The dual head constructionis also available on the Opti-Centric® MOT 300. It is usedto align and assemble com-plex and multi-lens objec-tives. It is possible to measure and align theupper and lower lens surfaces simultaneously.This proprietary design considerably improvesthe capabilities of the instrument in the fieldof optical assemblies and the measurementof centering errors. The travel on this addition-al axis is limited to 250 mm.

OptiCentric® MAX

The OptiCentric® MAX is the further develop-ment of OptiCentric® UltraStable. It was devel-oped for the measurement and productionof extreme heavy and large optics. OptiCen-tric® MAX consists of a vibration dampedtable, an air bearing AB300 and a positioningunit for the measuring head. The positioningof the measuring head is controlled by aclosed loop system, which allows the mea-

surement of radii and lens distances with ahigh precision.

A product version with a dual measuringhead is available, whereas the travel of themeasuring head stage is limited to 250 mm.With a maximum axial load of up to 500 kgand a free sample height of 1600 mm Opti-Centric® MAX can measure almost everylarge scale optics.A typical application is the adjustment andmounting of stepper optics.Optics with a weight up to 500 kg are posi-tioned directly on the air bearing. A tilt andtranslation table is not available.

The decentration of the optical elements inrespect to the reference axis of the barrel isdetermined by measuring the barrel with aprecise non-contact optical sensor or a me-

OptiCentric® MAX

OptiCentric® METRO

17

chanical gauge. Fromthe measurement datathe mechanical refer-ence of the barrel iscalculated and com-pared with the systemoverall reference axis(the rotation axis of therotary air bearing). Thecentering errors of theoptical lens elementsalready measured inrespect to the systemreference axis can nowbe recalculated takingas reference the me-chanical axis of thebarrel. The new dataset can be transferredto an automated align-ment device performing the accurate align-ment of the optical elements on the axis ofmechanical mount.

As all other TRIOPTICS instruments, OptiCen-tric® MAX can be individually adapted to thecustomer requirements, e.g. increasing thetravel of the measuring head stage, selectinga larger air bearing or adding equipment forcementing and bonding of lenses in mountsand thus creating a work station for a com-plete automated production process.

OptiCentric® Custom

In addition to the before mentioned configu-rations of the OptiCentric® product line, TRIOP-TICS also develops and manufactures cus-tom specific instruments. The developmentof custom instruments is based on existing TRI-OPTICS hardware and software platforms, sothat our customers benefit from the same lev-el of accuracy and reliability characteristic forour standard instruments. In the followingsome of the OptiCentric® Custom instrumentsare presented:

Measurement of Laser Rods

The quality of the laser rods is mainly influ-enced by the parallelism of laser rod end sur-faces and the homogeneity of the material.Ideally the light beam entering the laser rodshould exit without changing direction. How-ever, if the two end surfaces of the laser rodare not parallel and perpendicular to thecylinder axis, the traversing laser beam will bedeviated. Similarly, defects in the materialcontribute to the beam deflection.

The main parameters to be checked are:

• The parallelism of the laser rod end sur-faces which is measured in reflection mode

• The beam deviation through the laser rod which is measured in transmission mode

When the cylinder axis is given as a reference,and the centering errors of the rod end sur-faces to the cylinder axis are required, thelaser rod is additionally rotated .

The setup of the instrument is horizontal in or-der to allow the precise rotation of long laserrods up to 150 mm. A special software mod-

Customer-specific construction for the measurement of laser rod end surfaces

OptiCentric® METRO

18

ule controls the measurement and providesspecific data sets and measurement certifi-cates.

Measurement of C-lenses

A typical example from the field of micro op-tics is the measurement of C-lenses used forthe light transmission in glass fibers.

As a rule, C-lenses have an optical window onone side and a spherical surface on the otherand are typically long in relation with the di-ameter. A special rotation device has beendeveloped allowing for horizontal positioningand rotation of the C-lenses during the mea-surement. The rotation of lenses is accom-plished manually; the centering error of thespherical surface is measured in relation tothe cylindrical axis.

Accurate Radius Measurement

All OptiCentric® systems include an option forthe measurement of radii of curvature. Themeasurement principle is analog to that ofthe interferometric measurement procedure:

The autocollimator is initially focused on theupper surface of the sample and in a secondstage into the center of curvature of thesame surface. Due to the accurate autofo-cus feature, both positions can be detectedwith high sensitivity. The distance between thetwo positions, corresponding to the radius ofcurvature of the surface, is measured usingprecision linear encoders mounted on the in-strument stand.

In order to achieve the required 0.01% accu-racy of the radius measurement, a linear airbearing has been mounted instead of thestandard linear stage of the OptiCentric® sys-tem. The excellent straightness of the linear airbearing contributes essentially to the overallmeasurement accuracy. In addition to theaccurate radius measurement this instrumentis able to fulfill all the other jobs related tomeasurement of centering errors in multi-lenssystems or complex alignment tasks.

OptiCentric® Software

The advanced software is designed to workwith Windows XP® operating systems. The soft-ware fulfils the need of the optical shop foreasy, intuitive operation and features a num-ber of options to accommodate a large vari-ety of specific requirements.

The software modules „Centration in Transmis-sion“ and „Centration in Reflection“ provide anoutstanding accuracy even in difficult mea-suring situations such as poor contrast, anti-re-flection coated surfaces, very small lenses,etc. With the OptiCentric® Dual Head instru-ment the software optionally provides simulta-neous measurement data with two live im-ages for both lens surfaces. The software fea-tures selectable options to adapt the systemto different hardware configurations e.g. dif-ferent reticule patterns (bright cross, darkcross, pinhole, etc.). Several different mea-surement units like mm/inch, arcsec, microra-dians, etc. can be selected. To increase theproduction efficiency, the optimized processparameters can be saved for future use.OptiCentric® instrument with linear air bearing stage

OptiCentric® METRO

19

Additional features of the software

• Real time monitor display of the camera image from one or two measuring heads

• Real time, continuous display of the mea-surement values

• Vector display of the size and direction of the centering error

• HTML certificate output• Computer generated tolerance circles or

angle graduations for the quick analysis of production quantities

• Automatic adjustment to the sample reflec-tivity

• Automatic calibration procedure by meansof a calibrated sample, the calibration canbe verified at customer site

• Artificial crosshair for the initial alignment assistance

OptiCentric® MOT Extension Modules

Thanks to the modular design of the instru-ment software, new options and softwaremodules can be easily integrated in order toextend the measurement capabilities of theinstrument.

MultiLens®

This complex software module is used eitherfor the alignment and assembly of objectivelenses or for measuring the centering errors ofcompletely mounted optical assemblies. Theinspection of mounted objective lenses pro-vides precise data about the assembly quali-ty. In this way, the MultiLens® software be-comes an indispensable tool for optimizingthe manufacturing process.

Simultaneous measurement in reflection of both lens surfaces

OptiCentric® METRO

20

The MultiLens® software delivers in a con-structive way the complete informationabout the individual centering errors of allsurfaces in an assembly. The PC con-trolled OptiCentric® instrument performsstepwise a reflection mode centeringmeasurement starting with the first sur-face closest to the measuring head andcontinuing with the following surfaces.

The MultiLens® software performs a raytracing through the optical system basedon the lens design parameters and themeasured centering values. Finally, theoperator obtains a numerical and graph-ical output of the complete centeringstatus regarding shift and tilt of eachmeasured surface from the CentricAna-

Measurement of radii of curvature

OptiCentric® METRO

21

lyzer submodule. The module can calculatethe best-fit optical axis of the objective lensand all surface centering data can be refer-enced to this axis. Combining these featureswith adequate assembly techniques, highperformance objective lenses with tolerancesin the micron range can be easily centeredto best performance.

Advanced Analyzer

The Advanced Analyzer is a software tool inaddition to the MultiLens® software with evenmore analysis features and comprehensive3D graphical output. It is a self-contained soft-ware application. A separate copy can beordered to perform a detailed centeringanalysis independently from the instrument's

PC. Of course, if it is run on the same PC, themeasurement data is transferred automati-cally between the applications.The initial measurement data refer to the airbearing's axis of rotation, which is usually notthe desired result. The Advanced Analyzersoftware therefore calculates the following sit-uations:

• Calculate the optical axis passing through two or more centers of curvature. Weightingfactors can be applied to calculate the re-gression line depending on the optical power of the surfaces.

• Calculate angle and distance between twooptical axes (e.g. two single lenses)

• Calculate the surface tilt error of any sur-face relatively to the axis of reference.

Dual live Image for MultiLens® checking

OptiCentric® METRO

22

• Reference all other surfaces and optical el-ements relatively to any user defined opti-cal axis

• Reference relatively to the mechanical axis

AspheroCheck®

AspheroCheck® (Patent application 10 2006052 047.5-51) is a hardware and softwaremodule designed to measure the tilt and shiftof an aspherical axis with respect to a de-fined reference axis. The module is availableas an upgrade for all OptiCentric® Systems

equipped with a rotar y airbearing sample stage.

The AspheroCheck® moduleconsists of a high-resolution As-pheroCheck® distance sensormounted on a x-z linear stagesystem. The angle of the sensorcan be adjusted square to thesample sur face by a rotarystage. Every point along theradius of the sample can thusbe reached by the sensor. Thestandard module is operatedmanually, a motorized versionis available on request.

OptiCentric® AspheroCheck®

Fig. 8a: Lens with aspherical and spherical surface Fig. 8b: Lens with two aspherical surface

OptiCentric® METRO

23

During the measurement, the AspheroCheck®

sensor is moved close to the outer edge ofthe lens in order to capture the eccentricity ofthe surface during rotation. At the same time,the autocollimator determines the centeringerror of the surface in the paraxial area. Bothvalues are then combined to determine theposition and the tilt of the aspherical axis.

The following parameters of aspherical lensescan be measured:

1) Shift and tilt of the asphere axis in relation to the reference axis of rotation.

2) Shift and tilt of the asphere axis in relation to the optical axis of the lens. The “optical axis” is considered to be the line running through the centers of curvatures of the spherical portions.

3) When a lens consists of two aspherical sur-faces the angle and shift of both asphericalaxes are determined.

CylinderCheck®

CylinderCheck® is a software and hardwaremodule for the precise measurement of cen-

Software Advanced Analyzer

Cylinder lenses checked by OptiCentric®

OptiCentric® METRO

24

tering errors of cylindrical surfaces. It requiresa specific hardware to align the sample andperform the measurement procedures. De-pending on the application, CylinderCheck®

can capture various parameters of the cylin-drical surface. Typical cylindrical lenses haveone cylindrical surface and one plano sur-face.

For these samples, typically the orientation ofthe cylindrical axis in relation to the lens edgeis measured. Additionally, it is possible tomeasure the angle between the cylindricalaxis and the opposite plano surface. A dedi-cated sample holder (see picture) is requiredfor both measurement types. CylinderCheck®

also gives the azimuth angle of the cylinderaxis relatively to a given edge. In addition,anamorphic lenses can be measured withthis tool.

Center Thickness

Besides measuring centering errors, the Opti-Centric® system is able to determine the dis-tance between optical surfaces inside of anoptical system. An individual distance (e.g.the center thickness of a lens), but also acomplete set of distances, including the cen-ter thickness of lenses and air gaps, can bemeasured non-destructively in an assembledobjective lens. Same as in the MultiLens®

measurement, this procedure requires the op-tical design data of the sample.

OptiCentric® offers two methods for this mea-surement. The first one uses the autocollima-tor with a lens attachment in order to deter-mine the cat's eye surface reflection positionof the surface under test. The difference be-tween two measured positions is used in con-junction with the design data (radii and re-fractive index) to calculate the actual dis-tance. This method works extremely well withone or two distances but can be noticeablyproblematic with three or more.

TRIOPTICS therefore offers an alternativemethod using an additional distance sensor,specifically developed for measuring dis-

tances inside optical systems. It is based onwhite-light interferometry and is able to mea-sure all center thicknesses in an objective lenswith an accuracy of about 1 µm.A selection of different center thicknessprobes is available for the integration into theinstrument. The standard white-light interfer-ometer captures lens distances within arange of 0 to 200 mm with an accuracy of 1µm. The high-end instrument measures lensdistances with an accuracy of 0.15 µm.

OptiSpheric®

With the extension module OptiSpheric®, themeasurement functionality of an OptiCentric®

instrument can be extended by the followingoptical parameters:

• EFL - Effective Focal Length• BFL - Back Focal Length• FFL - Flange Focal Length• Radius of Curvature• MTF on-axis

Besides the software functions, the OptiSpher-ic® module consists of an additional collima-tor mounted with a 90° deflection mirror in thebase of the instrument. It is equipped with aselection of test targets for the different mea-surement options.

OptiAngle®

The software module OptiAngle® and someadditional mechanical fixtures convert theOptiCentric® instrument into a powerful toolfor angle measurements, including:

• Wedges and filters• 90°-prisms• Parallelism of parallel plates• Deviation angle through wedges and prisms• Mirror tilt• Alignment of CD/DVD optical heads• Wobble of rotating disks

More detailed information on the measure-ment of plano optics is included in the TRIOP-TICS OptiAngle® brochure.

ASSEMBLY OF OPTICS

25

Automated Cementing of Lenses

For many lens manufacturers the cementingof two or three optical elements to a doubletor triplet is still a laborious process accom-plished manually and prone to operator er-rors. The classical technology requires an ac-curate rotation device - whose axis serves asa reference axis - and a sample holder whichmust be either very accurate (and expensive)or precisely aligned to the reference axis.

The operator needs to accurately align thelens holder until the axis of the bottom lenscoincides with the rotation reference axis.Once the bottom lens is aligned and the ce-ment layer dispensed on the joint surface, theoperator adjusts -mostly manually- the upperlens until the axis of the upper lens surfacecoincides with the reference axis. It is obviousthat the accurate alignment of the bottomlens in a first step and the alignment of theupper surface in a second step is a time con-suming and rather unstable process depend-ing largely on the operator skills. Moreover,both alignments of the bottom and upperlens are carried out relatively to a reference

axis and not directly to each other. Conse-quently, inherent inaccuracies will always goalong with this technology.

The new cementing technology developedby TRIOPTICS is controlled by the softwaremodule SmartAlign®. The basic idea of thisconcept is to accurately measure and assessthe positions of the three centers of curvatureof both lenses. The measurement is done rel-atively to an accurate reference rotation axisin just a few seconds with submicron accura-cy. In a next step the upper lens is aligned insuch a way that the center of curvature of theupper surface coincides with the optical axisof the bottom lens without the need of anymechanical pre-alignment (see Fig. 8).

In the automated process, the measurementdata set containing the position of the threecenters of curvatures is transferred to an auto-matic alignment device equipped with ap-propriate lens manipulators. In the next fewseconds the upper lens is aligned to the bot-tom lens with an accuracy in a range of 1µm. The complete process cycle includingmeasurement and alignment lasts less than10 seconds. If required, an UV-curing devicecan be integrated into the automated sys-tem.

Fig. 8: The SmartAlign® technology is used for the automated adjustment of achromatic lenses in the cementing process

Step 1: Position of

the 3 centers of curva-

ture is measured

Step 2: The upper lens is

automatically adjusted on

the axis of the bottom lens

Reference axis of rotation

(of the air bearing)

x - y - piezo

actuator

Ring-shaped lens

manipulator

Base lens fixed

to the rotor

Centre of curvature of the upper lens surface before and after adjustment

Rotor

Assembly of Optics

ASSEMBLY OF OPTICS

26

The SmartAlign® technology is supplied as aturnkey system under the product name Opti-Centric® Cementing Station. Certainly, up-grades of existing OptiCentric® MOT instru-ments equipped with rotary air bearing areavailable.

In conclusion, the SmartAlign® technologyprovides a software and technology conceptfor cementing of lenses with highest accura-cy and repeatability and without the need ofany mechanical pre-alignment. Further bene-fits result in the very short cycle time and thestability of the cementing process.

Automated Bonding of Lenses into a Mount

Bonding of lenses into a cell became thetechnology of choice for applications requir-ing very precise lens alignment and where se-vere vibration or temperature extremes areencountered such as military systems and sci-entific applications. When aligning a lens element in a cell it isnecessary to adjust the optical axis of the lensto coincide with the datum axis of the lenscell. The best alignment performance is pro-vided by the optical inspection in reflectionmode. An accurate reference rotary axis e.g.provided by an air bearing is also required.

The datum axis of the cell is either measuredwith an accurate mechanical gauge or anon-contact optical sensor. An alternative isthe use of precise hydrostatic cell holders en-suring repeatable clamping of the lens cell.Certainly the mechanical axis of the hydrosta-tic holder must be initially aligned until the da-tum axis of the holder runs true to the refer-ence axis of the air bearing.

Finally the bonding cement is applied and al-lowed to set or is cured using UV-light sources.

The bonding of lenses into a cell is a laboriousprocess requiring experience and remarkableoperator skills.

For this complex part of the optics assemblyprocess TRIOPTICS developed an automatedwork station known as OptiCentric® BondingStation. The features of this work station cangreatly simplify the optical assembly, reducethe risk of alignment and centering errors andincrease significantly the efficiency and stabil-ity of the process.

The heart of the system is a complex and sta-ble software integrating and automating theprocess of inspection, alignment, cement dis-pensing and curing.A schematic representation of the basicprocess is presented in Fig. 9. The work piece,a cell with the lens element set inside, isclamped using either an accurate hydrostaticholder or a more simple mechanical chuck.

When using accurate (hydrostatic) holders theaccuracy of the alignment of the cell to thereference axis depends on the accuracy ofthe holder itself. The disadvantage of thismethod is that the precision holder can beemployed for one cell diameter. A cell holderaccurate to 1-3 µm is expensive enough, theequipment for a large range of diameters be-comes really unaffordable.

The SmartAlign® technology integrated in thesoftware of the work station allows the use ofinexpensive mechanical chucks. The datumaxis of the cell is determined by measuringthe cell with a precise non-contact opticalsensor or a mechanical gauge. The datumaxis of the cell is compared with the systemoverall reference axis (the axis of the rotary airbearing). The measured centering errors ofthe lens element can now be recalculatedtaking the datum axis of the cell as reference.The new data set is fed to an automatedalignment device performing the accuratealignment of the lens elements. The com-plete process is shown in Fig. 9:

A) The work piece is rotated around the refer-ence axis of the air bearing. A set of mea-surement data is taken. The position of the

ASSEMBLY OF OPTICS

27

center of curvature of the both surfaces is as-sessed.

B) The dispenser is precisely positioned bymeans of a stepper motor stage in the spacebetween the cell and lens element. While thesample is rotated, the dispenser needle pro-duces a precise joint around the lens. The dis-pensing time is coordinated with the lens ro-tation.

C) and D) The data set obtained during themeasurement is transferred to a piezoelectricalignment device. Using an appropriate ma-nipulator, the device aligns the lens elementto the reference axis or the datum axis of thecell.

The process is completed by the automatedcuring of the cement using a UV-light sourceintegrated into the work station.

Lathe Centering

A common method ofproducing a preciselycentered lens assemblyor objective lens isbased on the produc-tion of precise sub-as-semblies, which are lat-er combined into a bar-rel of close mechanicaltolerance.

The advantage of thisprocedure is that themechanical manufac-turing and maintainingof the tolerances is bet-ter controlled than it isfor the optical counter-part. The sub-assembliesare manufactured bylathe centering, wherethe optic is mountedmore or less carelesslyinto an oversized lens

cell. The cell is then adjusted in a specialalignment chuck so that the optical axis coin-cides with the rotary axis of the lathe. After-wards the cell is machined to the final size in-cluding the reference surfaces well aligned tothe optical axis. This method is quite expen-sive, however it provides the highest qualityand is usually applied for precision optics.

The first step of this process is to bond eachindividual optical element into an oversizedlens cell with stress-free cement. In a secondstep the assembly is mounted on the chuckof the lathe and aligned with respect to therotation axis of the turning machine.For thisprocess two autocollimation telescopes withhead lenses focused to the centers of curva-ture of both lens surfaces are used. As acompromise, a single autocollimator may beused that measures both surfaces sequential-ly in MultiLens® mode. In the third step, after

Fig. 9: Automated bonding of lenses into a mount

Piezoactuator

Axis of rotation

Dispenser

Centre of curvature of the upper sphere before and after adjustment

A)

C) D)

B)

OptiCentric® PRO

28

lens alignment, the edge of the cell and theflange surface are machined to their final di-mensions of close tolerance. The lens cellsproduced in this way can now be inserted in-to a barrel with exact internal fit to manufac-ture an objective lens.

The OptiCentric® PRO line for production of-fers a range of fully automated cementing,bonding and lathe centering stations. Thepowerful products are fully automated andcomply in the basic configuration with theOptiCentric® MOT 100. All sub assemblies likea glue dispenser or the motorized stepper arePC controlled.

OptiCentric® Cementing Station

Lens manufacturing not only includes gluebonding of a lens to a barrel, but also thecentering and cementing of two lenses to adoublet. For this purpose TRIOPTICS has devel-oped the OptiCentric® Cementing Station asa supplement to the TRIOPTICS OptiCentric®

System.

It includes a 2-axis x-y piezoelectric fine posi-tioning stage and a lens specific grabber. Thegrabber does the precise positioning of theupper lens to the optimally centered positionwith respect to the lower lens. The centeringprocedure relies on the proprietary TRIOPTICSMultiLens® algorithm. It determines first the op-tical axis of the lower lens and calculates thetarget position for the top lens. The top lens isthen pushed by the piezo driven grabber to

the target posit ion undercontrol of the high resolutionCCD autocollimator. With thistechnology, doublets withcentering accuracies below1 micron can be achieved.Similar to the Bonding Sta-tion, the complete process iscomputer controlled. Drivenby customer demands in thehigh volume market of plas-t ic molded lenses theprocess has been optimizedfor throughput. The completecementing cycle includingUV curing and manual sam-ple handling is performedwithin less than 10 seconds.

OptiCentric® PRO

OptiCentric® Bonding Station

OptiCentric® Cementing Station with piezo electric finepositioning stage

OptiCentric® PRO

29


The TRIOPTICS Automatic Bonding Stationextends the capabilities of the OptiCentric®

System into automatic manufactur ingprocesses of optical components and sys-tems. Modern objective lenses rely moreand more on glue bonded componentswhich, besides the lower cost, save spaceand weight. The OptiCentric® Bonding Stationincludes all the devices necessary for theprecise and automated centering and gluebonding of lenses into barrels and other opti-cal subassemblies.

A glue dispenser is mounted on a motorizedx-z stepper motor stage for the automaticpositioning of the dispenser tip to the gluingposition. The dispensing process is computercontrolled and the glue can be dispensedcontinuously or segmented around the lens.

A second x-z stepper motor stage moves a pre-cision piezoelectric manipulator to the edge ofthe lens to be centered. The piezo manipulatorallows a fine positioning of the sample lens withsub-micron step resolution and accuracy. The centering process is controlled by the Opti-Centric® System which relies on a high resolutionCCD autocollimator and the precise sample ro-

OptiCentric® Bonding with three piezo manipulators forthe fast alignment of lenses

OptiCentric® Cementing Station

OptiCentric® PRO

30

tation with an air bearing. High-precision cen-tering results better than 2.5 microns are typi-cally achieved in 2 min, processing time in-cluding UV curing time. The UV curing of theglue after lens alignment is enabled by acomputer controlled UV light source and sev-eral light guide outlets.

The complete bonding process is controlledby an integrated software program for allfunctions. A simple scripting language allowsthe flexible programming of the bondingprocess.

The complete manufacturing cycle can beprogrammed with an easy teach-in proce-dure using the manual stage controls. Ofcourse, different procedures for varying sam-ple types can be saved in files for later use.

OptiCentric® Centering Lathe Station

The TRIOPTICS centering lathe station is basedon a highly precise vertical CNC lathe and anadjustment chuck for the precise and auto-matic sample alignment. The alignment isdone by a high-speed electromagnetic im-pulse drive and high end centering errorrecognition based on the TRIOPTICS OptiCen-tric® software module. The vertical lathe is de-signed with a compact and stiff natural gran-ite base, high precision linear stages and ahydrostatic spindle. The automatic alignmentchuck is adjusted by the impulse drives duringrotation until the coincidence between theoptical axis and the spindle axis is reached.The centering error of the lens is measured byan electronic autocollimator, and the mea-surement result is set in relation to the rotationphase of the spindle. Stroke impulses are ap-plied at the proper rotation phase until thecentering error reaches a minimum. After thelens is centered, the lens cell is CNC ma-chined to its final size.

The OptiCentric® Bonding Station in operation

OptiCentric® PRO / ACCESSORIES

31

The specification of the centering lathe is:

Centering accuracy: < 0.1 arcmin (tilt) < 2 μm (decenter)

Machining tolerances: < 2 μmFlatness of plano surfaces:< 1 μmCylindricity of lens cell: < 1 μm.

The following accessories are offered to ex-tend the use of OptiCentric® instruments.

Motorized Centering and Cementing Equip-ment with Vacuum Chuck

The vacuum unit is a rotation device to mea-sure the centering error of single lenses withthe outer edge as the reference. The lens isrotated using a motor-driven friction wheel

against a V-block. The lens is held in positionby vacuum. The control of all functions such as the pres-sure, rotational speed and vacuum pump isintegrated in one control unit. A compressedair line system is not required. The vacuum ro-tation fixture exhibits an excellent level of ac-curacy and reproducibility. Possible errors re-lating to the roughness of the outer cylinderare averaged out so that the results have avery high repeatability.

The maximum sample diameter for measure-ments with the standard vacuum unit is 75mm. A modified unit for measuring samplesup to 210 mm diameter is available.

The vacuum unit is the standard tool of Opti-Centric® MAN instruments but may be pur-chased as an accessory for OptiCentric® MOTto enable lens cementing using OptiCentric®

MOT.

Extension of Measurement Range

Measuring range of the OptiCentric® system islimited by the size of the upper surface radiuswhen measuring in reflection mode or the ef-fective focal length when measuring in trans-mission mode. TRIOPTICS provides a set of ad-ditional head lenses to extend the range ofradius and focal length up to +/- 2000 mm.On request special lenses can be provided

Fig. 10: Lathe Centering of lens cells

Accessories

Vacuum unit

A)

C2 C2 C2

C1 C1 C1

B) C)

ACCESSORIES

32

for larger values. Plano surfaces (radius = ∞)can be measured at any time with the bareautocollimator using the parallel optical pathby removing the head lenses.

Measuring Sensor and Linear MeasuringGauge

On request different mechanical measuringgauges are supplied with the OptiCentric® in-strument. Following gauges are available:

• A gauge for the linear stage of the mea-surement head to measure its position with +/-2 µm accuracy. The length of the linear measuring scale is aligned with the track of the OptiCentric® system. This gauge is required for precision measurement of radius of curvature or thickness.

• A lever gauge (Force 0.02 N, measurementrange of 0.6 mm, repeatability 0.1 µm) is used to measure or align sample housings with respect to the axis of rotation.

• A mechanical gauge with absolute accu-racy of 0.2 µm and measurement range of25 mm. It is used for alignment purposes, too.

Alignment Set

In order to align sample holders or directlyadjust the sample barrel and housing, a setwith two high-precision parallel flats (25 and50 mm diameter) and two glass balls with di-ameters of 4-12 mm and 14-28 mm is of-fered.

Illumination

Every OptiCentric® system is provided with asuitable light source. This is usually a 150 Whalogen cold-light source with a 1 m opticalfibre light guide. All TRIOPTICS autocollimatorsand collimators are fitted with a standard in-terface for the illumination so that various lightsources can be exchanged for one another.The following light sources are available:

• 150 W cold-light source with light guide• 250 W cold-light source with light guide• 20 W halogen lamp mounted directly on

the autocollimator lighting assembly for in-creased IR output

• 5 W filament bulb• 100 and 300 mW high-power light emitting

diodes (LED)

Every collimator and autocollimator is also fit-ted with a spectral filter. Depending on theapplication a green or white light filter is ap-plied.

Revolving Turret

The turret is recommended for the quick andsimple change of the head lenses. OptiCen-tric® offers a manual 4x changer and a mo-torized 6x changer. On request both changerscan be supplied assemblied on the measur-ing head.

Calibration Tool

TRIOPTICS offers calibration wedges for theregular inspection of the measurement accu-racy of the OptiCentric® system. The certifiedwedge angle is traceable back to internation-al standards. The wedge angle is certified toan accuracy of 1 arcsecond.

Measuring lens barrel with the lever gauge

APPLICATION OVERVIEW

33

Application Overview

OptiC

entric

®M

AN

OptiC

entric

®SM

ART

OptiC

entric

®M

OT 1

00

OptiC

entric

®M

OT 3

00 U

ltra S

table

®

OptiC

entric

®Bo

nding

OptiC

entric

®Cem

enting

OptiC

entric

®La

the C

enterin

g

Application

Use in mass production

Measurement in reflection mode

Measurement in transmission mode

Measurement of single lenses

Measurement of objective lenses

Cementing manual / automated

Bonding manual / automated

Lathe Centering

Standard features

Option


AVAILABLE CONFIGURATIONS

34

Overview of Available Configurations

OptiC

entric

®M

AN

OptiC

entric

®SM

ART

OptiC

entric

®M

OT 1

00

OptiC

entric

®M

OT 3

00 U

ltra S

table

®

OptiC

entric

®Bo

nding

OptiC

entric

®Cem

enting

OptiC

entric

®La

the C

enterin

g

Illumination

150 W cold-light source

250 W cold-light source

20 W halogen lamp (NIR)

100 or 300 mW LED

Bearings

Air bearing AB 100 (sample diameter 0.5-225 mm)

Air bearing AB 300 (sample diameter 0.5-600 mm)

Vacuum unit (sample diameter 1-5 mm)




Vacuum unit extension (sample diameter up to 210 mm)

Measuring Head

Single Head

Dual Head

Range of radii or effective focal length of the sample

0 to +/- 200 mm and plano surface





Measurement data

Visual reading on eye piece scale

Visual reading on monitor

PC + Software evaluation

Measurement head linear stage

Manual positioning

Automated positioning, PC controlled

OptiCentric® extension

MultiLens® / Analyser

AspheroCheck®

CylinderCheck®

SmartAlign®

Central thickness / high accuracy radius measurement

Plano optics (OptiAngle®)

OptiSpheric®

Standard features

Option

ORDER INFORMATION

35

Order Information

OptiCentric® Instruments Order Numbers

OptiCentric® MAN *

OptiCentric® MAN - / 250 / Single Head 4-100-02

OptiCentric® MAN - / 400 / Single Head 4-103-02

OptiCentric® MOT *

OptiCentric® MOT - / 225 / Single Head 4-400-02

OptiCentric® MOT - / 225 / Dual Head 4-405-02

OptiCentric® MOT 100 / 225 / Single Head 4-400-02 + 4-300-49

OptiCentric® MOT 100 / 600 / Single Head 4-401-06 + 4-300-49

OptiCentric® MOT 100 / 225 / Dual Head 4-405-02 + 4-300-49

OptiCentric® MOT 100 / 600 / Dual Head 4-405-06 + 4-300-49

OptiCentric® MOT 300 UltraStable *

OptiCentric® MOT 300 UltraStable / Single Head 4-401-08 + 4-305-49

OptiCentric® MOT 300 UltraStable / Dual Head 4-405-60 + 4-305-49

OptiCentric® MAX

OptiCentric® MAX 4-143-00

OptiCentric® SMART

OptiCentric® SMART / Single Head 4-139-00

OptiCentric® SMART / Dual Head 4-139-00 + 4-141-00

* OptiCentric® bearing / max sample diameter / head

Extension Moduls Order Numbers

MultiLens® 4-400-90

AdvancedAnalyzer 4-400-91

AspheroCheck® 4-400-99

CylinderCheck® 4-300-074

Center Thickness 450 mm 4-400-86

OptiSpheric® 4-600-380

OptiAngle® 4-600-240

Accessories Order Numbers

Motorized lens rotation device with vacuum Chuck 4-300-40

Extension of measurement range 4-400-200

Alignment tool set 4-500-92

Manual revolving turret 4-300-140

Precision, motorized and software controlled revolving turret 4-300-146 + 4-300-079

Complete device for calibration check 4-300-51

1388 Crittenden Road Rochester, NY 14623-2308 USAPhone: 585.473.6540 Fax: [email protected] www.mildex.com

Sales Agent:

Inspection, Alignment, Cementing and Assembly of Optics

Documents

Transcript of Inspection, Alignment, Cementing and Assembly of Optics