Coating proses

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www.skPhotonics.com [email protected] T. 042) 867-2227 F. 042) 867-2228 1 Coating Optical coatings are used to alter the reflectance, transmittance, absorbance, or polarizer properties of optical components. The optics being coated is usually called the substrate. The coating is deposited in high vacuum using the process of evaporation by either e-beam, resistive heat or IAD (Ion Assisted Deposition) in conjunction with an e-beam source. We can offer state-of-the-art equipment, advanced design software and highly experienced engineers to provide you with absolutely the highest level of support. Coating materials include metal (Au, Al, Ag, Ni-Cr, Cr and so on), dielectrics (Oxides, Fluorides and Sulfides) and semiconductors (Si, Ge). Optical interference coatings respond differently to s and p polarized light. For this reason, it is essential to specify s, p, or random (the average of the s and p performance) polarization when the angle of incidence exceeds 20 degrees. Now we can provide all kinds of coatings as follows: Antireflective Coatings Single Layer MgF 2 AR Coatings (SAR) Multilayer AR Coatings (VAR) Broadband Multilayer AR Coatings (WAR) Dual Wavelength Band AR Coatings (DAR) Partial Reflective Coatings Single Wavelength Band PR Coatings (SPR) Broadband PR Coatings (BPR) Beamsplitter Coatings Laser Line Polarization Beamsplitter Coatings (LPS) Broadband Polarization Beamsplitter Coatings (BPS) Dichroic Beamsplitters Mirrors Coatings (DBS) High Reflective Coatings Dielectric High Reflective Coatings (DHR) Metallic High Reflective Coatings (MHR) Diode Pumped Laser Optics Coatings (DPC) Multilayer dielectric coatings consist of stacking, alternatively, high and low index materials. The thickness of these materials is designed for a specific set of conditions (desired reflective / transmission values, absorption, angle of incidence and polarization). We can then, by use of optical monitoring techniques and computer automation of the coater accurately reproduces the desired coating for you. Besides, we can provide spectral curves from our Perkin-Elmer 900(UV/VIS/NIR) spectrophotometer on all of our coatings and our coatings meet the Standard Mil Spec tests shown below: Abrasion, Mil-C-675A Adhesion, Mil-M-13508C Hardness, Mil-M-13508C

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Transcript of Coating proses

Page 1: Coating proses

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Coating

Optical coatings are used to alter the reflectance, transmittance, absorbance, or polarizer properties of optical components. The optics being coated is usually called the substrate. The coating is deposited in high vacuum using the process of evaporation by either e-beam, resistive heat or IAD (Ion Assisted Deposition) in conjunction with an e-beam source. We can offer state-of-the-art equipment, advanced design software and highly experienced engineers to provide you with absolutely the highest level of support. Coating materials include metal (Au, Al, Ag, Ni-Cr, Cr and so on), dielectrics (Oxides, Fluorides and Sulfides) and semiconductors (Si, Ge). Optical interference coatings respond differently to s and p polarized light. For this reason, it is essential to specify s, p, or random (the average of the s and p performance) polarization when the angle of incidence exceeds 20 degrees.

Now we can provide all kinds of coatings as follows:

Antireflective Coatings Single Layer MgF2 AR Coatings (SAR) Multilayer AR Coatings (VAR) Broadband Multilayer AR Coatings (WAR) Dual Wavelength Band AR Coatings (DAR)

Partial Reflective Coatings Single Wavelength Band PR Coatings (SPR) Broadband PR Coatings (BPR)

Beamsplitter Coatings Laser Line Polarization Beamsplitter Coatings (LPS) Broadband Polarization Beamsplitter Coatings (BPS) Dichroic Beamsplitters Mirrors Coatings (DBS)

High Reflective Coatings Dielectric High Reflective Coatings (DHR) Metallic High Reflective Coatings (MHR) Diode Pumped Laser Optics Coatings (DPC)

Multilayer dielectric coatings consist of stacking, alternatively, high and low index materials. The thickness of these materials is designed for a specific set of conditions (desired reflective / transmission values, absorption, angle of incidence and polarization). We can then, by use of optical monitoring techniques and computer automation of the coater accurately reproduces the desired coating for you.

Besides, we can provide spectral curves from our Perkin-Elmer 900(UV/VIS/NIR) spectrophotometer on all of our coatings and our coatings meet the Standard Mil Spec tests shown below:

Abrasion, Mil-C-675A Adhesion, Mil-M-13508C Hardness, Mil-M-13508C

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Antireflective Coating

Antireflective (AR) coatings increase transmission by reducing surface reflectance losses and improve image quality by reducing multiple surface reflectance. AR coatings may be applied to many substrate types such as: Glass, Silicon, Sapphire, Quartz and Others. These coatings can be applied to flat or curved surfaces such as lenses and spheres.

Now we can provide all kinds of antireflective coatings as follows:

Single Layer MgF2 AR Coatings Multilayer AR Coatings Broadband Multilayer AR Coatings Dual Wavelength Band AR Coatings

Single Layer MgF2 Antireflective Coatings (SAR)

Magnesium fluoride is probably the most widely used thin film material for optical coatings. Its performance is not outstanding but represents a significant improvement over an uncoated surface because its index is too high to provide a good impedance match at the air-glass interface.

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Multilayer Antireflective Coatings (VAR)

Such antireflective coatings can reaches the lowest reflectivity at a center wavelength. It is often applied to single laser wavelength or multiple, closely-spaced wavelength system to guarantee the lowest loss for center wavelength. We can provide such coating with center wavelength from 250nm to 2200nm. When selecting a suitable multilayer antireflective coating, the center wavelength and damage threshold must be paid attention to.

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Multilayer Broadband Antireflective Coatings (WAR)

Different from single layer MgF2 broadband antireflective coating, the multilayer Broadband antireflective coating can reaches higher transmission for broadband spectrum. Therefore, it is the ideal for a wide range of multi-wavelength laser and white light application. Please notify that the wavelength range and reflectivity of the coating are obviously changed according to the incident angle.

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Dual Wavelength Band Antireflective Coatings (DAR)

This coating allows two center wavelengths radiation pass through the substrate with high transmission. This coating is often used in frequency doubling systems or the other multi-laser output systems, as the Nd:YVO4 laser (1064nm) and its second harmonic generation (532nm) green laser.

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Partial Reflective Coating

Now we can provide all kinds of partial reflective coatings as follows:

Single Wavelength band Partial Reflective Coatings Broadband Partial Reflective Coatings Polarization Beamsplitter Coatings

Single Wavelength Band Partial Reflective Coatings (SPR)

When a narrow wavelength radiation is incident on this coating, part of the radiation is reflected and part is transmitted. Such coating always shows a high reflectivity for S-polarization radiation and high transmission for P-polarization radiations. The main application of this coating is to form a beamsplitter with 45° angle of incident. The non-polarizing beamsplitter plate and cube which are shown in the chapter "Beamsplitter" are coated with such coatings.

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Broadband Partial Reflective Coatings (BPR)

This coating has similar performance of to that of the Single Wavelength Band Partial Reflective Coatings, but there is an obvious difference between them. That is, it can be applied to split the incident radiation over a wide spectrum. The wavelength range of light, partial reflectivity and partial transmission can be accurately controlled to customer's specifications by our company.

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High Reflective Coating

Now we can provide all kinds of High Reflective Coatings as follows:

Dielectric High Reflective Coatings Metallic High Reflective Coatings Diode Pumped Laser Optics Coatings

Dielectric High Reflective Coatings (DHR)

It is well know that dielectric coating can reaches high reflection (more than 99.8% at designed wavelength can be available by our company) and generally used in single wavelength laser cavity where the lowest cavity loss at a center wavelength is essential. We can provide such coating with center wavelength from 250nm to 2200nm according to customer’s special inquiry. When selecting a suitable dielectric high reflective coating, the damage threshold must be paid attention to.

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Metallic High Reflective Coatings (MHR)

We provide metallic high reflective coatings by material of Au, Ag, Al, Cr, and Ni-Cr. These coatings are applied to where the consistent high reflection in a wide spectral rang is necessary. Their reflectivity is not higher than dielectrics HR coatings, but their HR spectrum can over near-UV, visible and near-IR. In order to prevent these metallic coatings from oxidization, these coatings have been deposited on a layer of dielectrics coating.

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Diode Pumped Laser Optics Coatings (DPC)

We provide the following coatings for the Nd-Laser application. These coatings are deposited on substrates of BBO, KTP, Nd:YVO4, Nd:YAG and BK7 and mainly used to Nd Laser and their harmonic generation.

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Beamsplitter Coating

Now we can provide all kinds of beamsplitter coatings as follows:

Laser Line Polarization Beamsplitter Coatings Broadband Polarization Beamsplitter Coatings Dichroic Beamsplitters Mirrors Coatings

Laser Line Polarization Beamsplitter Coatings (LPS)

This coating has special performance of nearly 100% reflectivity for S-Polarization and 100% transmission for P-polarization at a narrow wavelength bandwidth. Therefore, it main application is to be used as polarizing beamsplitter in single wavelength laser system when it is deposited on glass substrate. But its extinction ratio is not so high.

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Broadband Polarization Beamsplitter Coatings (BPS)

It has similar application with Laser Line Polarization Beamsplitter Coating but it can be used in a wide range spectrum. This spectral range can be controlled by our company according to customer’s special inquiry.

Dichroic Beamsplitter Mirrors Coatings

The main application of these coating is splitting different wavelength radiation. The DBS-SP coatings perform high transmission for short wavelength but high reflection for long wavelength, and the inverse case for DBS-LP coating. The DBS-HP coatings are used to separate harmonic generated lasers. The following graphics show the contrasted transmission for 1064nm laser and 532nm its second harmonic laser.

Short Wave Pass Dichroic Beamsplitter Mirror Coatings (DBS-SP) Long Wave Pass Dichroic Beamsplitter Mirror Coatings (DBS-LP) Harmonic Separators (DBS-HP)

R>99.8%@1064nm

R<5%@532nm

R>99.8%@532nm

R<5%@1064nm

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Transmision Curve

BK7

BK7 is a borosilicate crown optical glass with high homogeneity and low bubble and inclusion content. Its good physical and chemical properties make it widely used in visible and NIR windows, lenses and prisms.

Transmission range: 330nm ~ 2100nm Thermal Expansion Coefficient: 7.5 × 10-6/K Density: 2.51g/cm3

Fused Silica

Fused silica is formed by chemical combination of silicon and oxygen. Advantages of fused silica material include good UV and IR transmission, low coefficient of thermal expansion, providing stability and resistance to thermal shock over large temperature excursions, wider thermal operating range and high laser damage threshold. Used for windows, lenses, prisms and mirror substrates.

Transmission Range: 185nm ~ 2500nm Thermal Expansion Coefficient: 0.54 × 10-6/K Density: 2.20g/cm3

Sapphire

Sapphire is a single crystal aluminum oxide or Al2O3 and is one of the hardest materials, which have good transmission characteristics over the visible, and near IR spectrum. Sapphire exhibits high mechanical strength, chemical resistance and thermal stability. It is often used in environment where scratch resistance is importance.

Transmission Range: 180nm ~ 4500nm Thermal Expansion Coefficient: 8.4 × 10-6/K Density: 3.98g/cm3

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CaF2

CaF2 is a crystal which has good transmission from 170nm to 7800nm. It is slightly soluble in water and is susceptible to thermal shock. Common CaF2 uses include IR components such as windows, lenses and prisms.

Transmission range: 170nm ~ 7800nm Thermal expansion coefficient: 18.85 × 10-6/K Density: 3.18g/cm3

Crystal Quartz

Crystal quartz is a positive uniaxial birefringent single crystal. Our crystal quartz is selected to minimize inclusions and refractive index variation. Crystal quartz is most commonly used for high damage threshold waveplates.

Transmission range: 200nm ~ 2300nm Thermal expansion coefficient: 7.07 × 10-6/K Density: 2.65g/cm3

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Optical Materials

We have strong capability in fabricating optical components with various optical materials. The most important material properties to consider for an optical element are transmission versus wavelength, index of refraction, thermal characteristics, mechanical and chemical characteristics and cost. There are two instances in which you might need to know more about optical materials. First, you may need to determine the performance of a catalog component in a particular application. Second, you may need specific information when selecting the material for a custom component. The data in the following is intended to assist in these situations.

To select the right materials seems overwhelming. The simplest way is to let us know your applications, and we select them for you.

Some of the materials that Our Company uses include:

General Optical Glass Schott Glass, Ohara Glass Special Glass Fused Silica, Color Glass, Float Glass, Zerodur…

Sapphire, CaF2, BaF2, MgF2, LiF, KBr, KCl, NaCl, MgO… Quartz, Silicon, Ge, ZnSe, ZnS, GaAs… Optical Crystal

Calcite, YVO4, LiNbO3, BBO, TeO2, LBO, KTP, YAG…

Materials Refractive Index Transmission Range (μm)

Thermal Expansion Coefficient (10-6/K)

BK7 1.5164 (588nm) 0.330 - 2.1 7.1 SF11 1.78472 (588nm) 0.370 - 2.5 6.1 SF14 1.76182 (588nm) 0.420 - 2.0 6.6

Fused Silica 1.4858 (308nm) 0.185 - 2.5 0.50 CaF2 1.399 (5.0μm) 0.170 - 7.8 18.85

Sapphire 1.755 (1.0μm) 0.180 - 4.5 8.4 Silicon 3.4179 (10 μm) 1.200 - 7.0 2.23

Ge 4.003 (10 μm) 1.900 - 16 5.7 ZnSe 2.40 (10 μm) 0.630 - 18 7.1 ZnS 2.2 (10 μm) 0.380 - 14 6.5

MgF2 no=1.3836 ne=1.3957 (405nm) 0.130 - 7.0 8.8 || c; 13.1 || a YVO4 no =1.9500 ne=2.1554 (1.3μm) 0.400 - 5.0 11.37 || c; 4.43 || a

CaCO3 (Calcite) no =1.6557 ne=1.4852 (633nm) 0.210 - 2.3 24.39 || c; 5.68 || a Quartz no =1.5427 ne=1.5518 (633nm) 0.200 - 2.3 6.88 || c; 12.38 || a a-BBO no =1.6749 ne=15555 (532nm) 0.190 - 3.5 33.3 || c; 0.5 || a LiNbO3 no =2.2863 ne=2.2027 (633nm) 0.370 - 4.5 4.1 || c; 14.8 || a

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IR Material

Many different types of material will transmit the infra-red. Selection of the most appropriate material is usually made with reference to the extent of the required transmittance and the nature of the environments being isolated by the window.

Zinc Selenide (ZnSe), Zinc Sulphide (ZnS), Germanium (Ge) or Gallium Arsenide (GeAs) are commonly used for the broad IR spectrum including both 3-5µm and 8-14µm bands.

Calcium Fluoride and Magnesium Fluoride are used in the 3-5µm band while maintaining high transmittance in the visible. Here are some of the commonly available materials:

Material Transmission Range (μm)

ZnSe 0.68~18.0 ZnS 0.38~14.0 Ge 1.90~16.0

Silicon 1.20~7.00 CaF2 0.17~7.80 MgF2 0.13~7.00

Lens & Windows

Typical diameters offered are: 6.35, 10.0, 12.7, 25.4, 38.1, 50.8, 76.3 and 200mm.

Thickness varies from 1.0 to 6.0 mm as appropriate to maintain the flatness specification.