7th R&D Colloquiu'm Washifgton, 23 & 24 June 19S2LJAdvamce RegisFttion FarmL

Wednesday & Thursday, 23 & 24 June, at The Shoreham Hotel, 2500 Calvert St., N.W., Washington, D.C.

Registrant's Name(last name) (first name and initial)

Affiliation

Maiiling Address(street and number)

(citv) (state and zin) (telephone number)

O Please check here if you need special services due to handicap. We will contact you prior to the meeting.

Enclosed is a check, purchase order, or credit card information (see below) for:

O $125 Full Registration (sessions, three meals, R&D: FY 83 Report, and Proceedings)J $ 70 Partial Registration (sessions, Report, and Proceedings)n $ 35 Student Registration (sessions, Report, and Proceedings; fulltime graduate or undergraduate only)Separate Meal Tickets (lunches at $17 and dinner at $25; no refund for meals after 21 June)O Lunch on Wednesday, 23rd 0 Dinner on Wednesday, 23rd 0 Lunch on Thursday, 24th

Program, badge, meal tickets, and R&D: FY 83 Report will be mailed 12 June. Registrations received after 12 June will beheld at the AAAS Registration Desk at The Shoreham Hotel. Reports from previous years (order below) will be sent as soon aspossible. Proceedings of '82 Colloquium will be sent as soon as available.

Previous Reports and Proceedings ($5 each book): 0 R&D: FY 82 0 R&D: FY 81 0 R&D: FY 800 Proc. 81 Col. 0 Proc. 80 Col. 0 Proc. 79 Col.

Charge to my 0 VISA or 0 MASTERCARD Number Expires

Cardholder's signature

Shoreham Hotel Reservation-AAAS Colloquium (23 & 24 June)(Reservations received after 23 May cannot be guaranteed)

Names and Addresses of All Occupants of Room:

Name __ Name _

Address Address

City State Zip City _ State Zip

Room: .Single ($70*) ..Double ($84*) -Twin ($84*) (*Plus 1007o D.C. sales tax and 80¢ occupancy tax.)

Be sure to list delinite arrival and departuireArrival: Date _____________________ Time (late and time. Hotel reservations *iill be held

ontvt uittil 6 p. in. unless otherwise specified.Departure: Date Time Check out time is 1:00 p.mi.

Please indicate any specialhousing needs due to handicap

Enclose separate check, made out to The Shoreham Hotel, for first night's room deposit or indicate major credit card number:

Credit card name Number ___ Expires

Cardholder's signaturepT.

I

id

23 APRIL 1982 357

I

2 in a series ofreport onnewtechnologyromXerox

Few inventions haveproved more versatile thanthe laser

It has been used as a supersignal lampforspacecommunications. It hasfound a role in exotic metal-working applications, and the incredible precision that itoffers has made new kinds ofbrain and eye surgerypossible.

A systemforplaying TVshowsfrom phonograph-like disks uses a laser to "read" the recordedprogrammaterial.

Lasers are used in variousforms ofmeasurementand information handling systems. For example, oneversion ofthe bar-code reader used in supermarketsemploys a laser scanner.

The Hologon Laser Scanner is one ofthe latestdevelopments in practical applications oflaser technologyIt was invented by Xerox opticalphysicist Dr. CharlesKramer who wvrote this article.

Lasers In Electronic PrintingAt Xerox we use lasers in electronic printing

systems that are based on xerography.' Instead ofmaking copies ofexisting documents, such printerscreate documents, drawing on information storedin a computer. In such a system, signals from thecomputer pulse the laser beam as it scans across alight-sensitive drum or belt that serves as the"camera film" in xerography. The image recordedin this way is then developed and transferred to

358

paper asm a copier.Laser electronic printers offer the quality of

offset printimg with significant versatility com-pared with conventional computer printers. Thereis virtually no meaningful limit to format or totype style or size. Pictorial or other graphicmaterial can be printed as easily as text. Arabic,Greek or Russian alphabets-even Oriental ideo-grams -are within its capabilities, provided appro-priate programming is fed into the printing system.

Equally significant is the fact that, withelectronic prmitmig, documents origimated m onelocation can be printed simultaneously at a numberofdifferent locations.

Xerox currently offers three such systems. The9700 electronic printing system turns out almosttwo pages per second and has almost unlimited flex-ibility when it is used with the Xerox IntegratedComposition System program. The 5700 elec-tronic printing system is up to 40 times faster thanconventional word-processing printers, which itcan replace, and it can also be used for electronicmail and remote computer printing. A similarprinter is offered as part ofthe Xerox 8000 net-work system. Designed for lower-volume applica-tions, it is twelve times faster than a conventionalword-processing printer.

In these printers, the scanning action ofthelaser beam is created by a relatively complex opti-

SCIENCE, VOL. 216

molow ---PI

cal system that is based on a rotating, polygonalprism. Extremely high precision is required in sucha system. This complexity and precision make sucha laser scanner relatively expensive.The Hologon Laser Scanner

To simplify laser scanners and reduce theircost, we considered holography to perform thefunctions ofcostly lenses and prisms.

Holographic recordings, best known for theirreproduction ofthree-dimensional images, take theform ofgratings-corrugated or ridged patternson a transparent medium, having a spacing ofapproximately twenty millionths ofan inch. Inpictorial holograms, these gratings contain therecorded cross section of the wavefront oflight

Hologon Laser ScannerInmage Plane Motion

DeflectedBeam

Beam

Hologon

Motor

that had been reflected from the pictorial subject.When coherent light-usually from a laser -istransmitted through such a hologram, a true three-dimensional image ofthe subject is reproduced.

However, the holographic gratings used in aHologon scanning system do not contain pictorialinformation. Only the optical diffraction proper-ties ofthe gratings are utilized.

The Hologon System is one ofseveral holo-graphic approaches to scanning. But the otherstend to scan in an arc-like pattern which is unsuit-able for electronic printing, which requires astraight-line scan, much like the raster pattern usedin television to create an image. The Hologonapproach gets around this problem through a

novel configuration.In a Hologon, a series of holographic gratings

are formed around the circumference ofa trans-parent disk. A laser shines through these gratings asthe disk rotates. The gratings diffract the laser light,and the rotating action causes it to scan across thesurface on which it is focused, as shown in theaccompanying diagram. Focusing is done by asimple, inexpensive lens.

The laser beam in this system is aimed so that itforms a nominal 450 angle to the Hologons sur-face as it enters a grating and a 450 angle as itemerges from the grating. In other words, it is dif-fracted through a right angle by the gratings. Thisangling results in a straight-line scan.

Because of the optical properties ofthe holo-graphic gratings, the 900 diffraction angle ofthebeam is maintained even ifthe Hologon surfacewobbles as it rotates. The beam angle is equally un-affected by eccentricities in the rotating disk.

This insensitivity to mechanical variation,plus the ease and low cost with which Hologon

disks can be produced, make a Hologon laser>\\ scanning system relatively inexpensive.

Work is currently underway at Xeroxon a new generation oflaser printing sys-tems utilizing the Hologon laser scannerwith all its attendant benefits. Thisshould enable Xerox to make theadvantages ofelectronic printingmore widely available than everbefore.

About The AuthorDr. Charles Kramer is the inventor ofthe

Hologon Laser Scanner. He is an optical physicistspecializing in electro-optcal reading and printingdevices at the XeroxJoseph C. Wilson Center forTechnology inRochester, New_York.

He holds aBachelor's degreeand a Master's degreein Physics fromFairleigh DickinsonUnive-rsity and aMaster's degree andPh.D in Opticsfrom the UniversityofRochester..

XEROX0 isatrademarkof XEROX CORPORATION.

23 APRIL 1982

XEROX359

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