OPTICAL-MATERIALS

OPTICAL-MATERIALS COHERENT | Alldatasheet

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World’s Leading Producer of Optical Materials

• Zinc Selenide (ZnSe)
• Zinc Sulfide (ZnS)
• Zinc Sulfide MultiSpectral (ZnS MS) Chemical Vapor Deposition Furnace Coherent Incorporated was founded in 1971 to supply bet- ter materials to infrared optics producers. Initially producing cadmium telluride, Coherent began producing zinc selenide in the 1980s, and zinc sulfide during the 1990s. Today, Co- herent’s vertical integration, from materials growth through precision optics manufacturing, positions the company as the worldwide leader in CO2 laser optics. Coherent is also the world’s leading producer of ZnSe material. And our ZnS regular and ZnS MultiSpectral materials are used in a growing number of infrared systems both domestically and abroad. This brochure provides a comprehensive overview of our infrared materials capabilities. For additional informa- tion, contact a Coherent sales and support representative.

Optical Fabrication Options Coherent offers its infrared materials to customers who have their own optical manufacturing capability. Our ZnSe, ZnS, and ZnS MS are offered in a variety of shapes and configurations. Sheet Material Materials can be ordered in sheet form by specifying the material’s length x width x thickness. The materi- al will be supplied to minimum +0.200” over the specified length and width. The thickness provided will be minimum +0.010” over specified thickness. Sufficient Material To Yield (SMTY) Material ordered in this manner will be provided in irregularly shaped configurations that have been measured with templates to ensure they will yield a predetermined quantity of specific diameters. The thickness provided will be minimum +0.010” over specified thickness. It is important to take into account material removal amounts before specifying a SMTY thickness. Core-Drilled Blanks Core-drilled blanks are initially machined with the closest oversized diameter core-drill tool that’s at least 0.080” greater than the core-drilled blank diameter required by the customer. Core-drilled blanks have no bevels, edge chips will not exceed 0.030”, and thickness is held to +/-0.010”. Edged Blanks Circular, square or rectangular parts are specified with standard dimensional tolerances of +0.000”/- Bevels can be provided when specified by customer. Generated Curved Lens Blanks Blanks can be ordered with curves generated and edges beveled. Standard thickness tolerance is +/- 0.010”. Tolerances on radii depend upon the curve steepness in relation to diameter. Surface Finishes Coherent offers the following surface finishes on ZnSe, ZnS, and ZnS MS blanks. Core-drilled blanks may contain any of the standard surface finishes unless otherwise specified. As Generated (AG) Requires additional grinding prior to further processing for an optical finish. Fine Ground (FG) Dull fine-ground finish free of scratches as viewed by the unaided eye. View Polished (VP) Multi-stage mechanically polished to a transparent finish as viewed by the unaided eye; requires further processing for an optical finish. Used for inspection of internal quality cosmetics to guarantee the visual quality of the material. Edges are beveled and free of chips as viewed by the unaided eye.

Zinc Selenide (ZnSe) ZnSe is a preferred material for lenses, windows, output couplers, and beam expanders for its low absorptivity at infrared wavelengths and its visible transmission. For high-power applications, it’s critical that the material bulk absorption and internal defect structure be carefully con- trolled, that minimum-damage polishing technology be employed, and the highest quality optical thin-film coatings be used. The material absorption is verified by CO2 laser vacuum calorimetry. Our quality assurance department provides testing and specific optics certification on request. ZnSe optics are routinely polished from 5 to 300 mm in diameter. Sizes greater than 300 mm diameter and 25mm thick are manufactured to customer requirements. ZnSe is non-hygroscopic and chemically stable, unless treated with strong acids. It’s safe to use in most industrial, field, and laboratory environments. Prism Grade Zinc Selenide (ZnSe) Coherent has the capability to grow prism grade ZnSe exceeding 2.50” thick. Prism grade ZnSe exhibits minimal refractive index variations within the material on planes perpendicular to the growth direction as well as in other directions. Index variations will test to less than 3 ppm at 0.6328 mi- crons regardless of orientation. Prism grade ZnSe is com- monly used in thermal imaging systems. Call our technical sales staff to discuss your specific requirements.

• Thickness exceeding 2.50”
• Consistent optical performance independent of orientation
• Refractive index variation less than 3 ppm @ 0.6328µm in all directions ZnSe Material Properties All values @ 20°C Physical Properties Structure Cubic zincblende Density 5.27 g/cm3 Grain Size < 100 μm Inclusions None > 0.05 mm Electrical Density > 1012 ohm-cm Dielectric Constant Consult our technical staff Optical Properties Bulk Absorption Coefficient @ 10.6 μm < 0.0005 cm-1 Thermo-Optic Coefficient (dn/dT) @ 10.6 μm 6.1 x 10-5/°C Refractive Index Inhomogeneity @ 0.6328 μm < 3 x 10-6 Thermal Properties Thermal Conductivity @ 20° C 0.18 W/cm/°C Specific Heat 0.356 J/g/°C Linear Expansion Coefficient @ 20° C 7.57 x 10-6/°C Mechanical Properties Young’s Modulus 67.2 GPa (9.75 x 106 psi) Rupture Modulus 55.1 MPa (8,000 psi) Knoop Hardness 105-120 kg/mm2 Density 5.27 g/cm3 Poisson’s Ratio 0.28 Fracture Toughness 0.5 x 106 N/m3/2

(µm) Index Wavelength (µm) Index 0.54 2.6754 7.4 2.4201 0.58 2.6312 7.8 2.4183 0.62 2.5994 8.2 2.4163 0.66 2.5755 8.6 2.4143 0.70 2.5568 9.0 2.4122 0.74 2.5418 9.4 2.4100 0.78 2.5295 9.8 2.4077 0.82 2.5193 10.2 2.4053 0.86 2.5107 10.6 2.4028 0.90 2.5034 11.0 2.4001 0.94 2.4971 11.4 2.3974 0.98 2.4916 11.8 2.3945 1.0 2.4892 12.2 2.3915 1.4 2.4609 12.6 2.3883 1.8 2.4496 13.0 2.3850 2.2 2.4437 13.4 2.3816 2.6 2.4401 13.8 2.3781 3.0 2.4376 14.2 2.3744 3.4 2.4356 14.6 2.3705 3.8 2.4339 15.0 2.3665 4.2 2.4324 15.4 2.3623 4.6 2.4309 15.8 2.3579 5.0 2.4295 16.2 2.3534 5.4 2.4281 16.6 2.3487 5.8 2.4266 17.0 2.3448 6.2 2.4251 17.4 2.3387 6.6 2.4235 17.8 2.3333 7.0 2.4218 18.2 2.3278 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 W avelength (/microm) Transmission ZnSe Transmission vs. Temper ature - 3 mm thick - 400°C 300°C 200°C 100°C 25°C 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0123456789 10 11 12 13 14 15 16 17 18 W avelength(/microm) Transmission ZnSe T ransmission - 6.3 mm thick - Temper ature °C dn/dT 10 ZnSe Thermo-Optic Coefficient (dn/dT) 0.6328/microm 1.5/microm 3.39/microm 10.6/microm -180 -140 -100 -60 -20 100 140 180 200

Zinc Sulfide MultiSpectral (ZnS MS) ZnS MultiSpectral is Coherent’s zinc sulfide material treated by a hot isostatic press (HIP) process. Under intense heat and pressure, defects within the crystalline lattice are virtually eliminated, leaving a water-clear material with minimal scatter and high transmission characteristics from 0.4 to 12 µm. This material is particularly well suited for high- performance common aperture systems that must perform across a broad wavelength spectrum. Coherent’s extensive capabilities, equipment, and experience enable us to offer ZnS MS material to exacting specifications of dimensional shape and tolerances. ZnS MS material is also available in random sizes and shapes for use as evaporative source material. ZnS MS Material Properties All values @ 20°C Physical Properties Structure Cubic zincblende Density 4.09 g/cm3 Grain Size 20 to 100 µm Inclusions None > 0.2 mm Electrical Density > 1012 ohm-cm Dielectric Constant Consult our technical staff Optical Properties Bulk Absorption Coefficient @ 10.6 µm _< 0.20 cm-1 Thermo-Optic Coefficient (dn/dT) @ 10.6 µm 5.4 x 10 -5/°C Refractive Index Inhomogeneity @ 0.6328 µm < 20 x 10-6 Near Angle Forward Scatter @ 0.6328 µm < 6%/cm Thermal Properties Thermal Conductivity @ 20° C 0.27W/cm/°C Specific Heat 0.527 J/g/°C Linear Expansion Coefficient @ 20° C 6.5 x 10 -6/°C Mechanical Properties Young’s Modulus 85.5 GPa (12.4 x 10 6 psi) Rupture Modulus 68.9 MPa (10,000 psi) Knoop Hardness 150-160 kg/mm 2 Density 4.09 g/cm3 Poisson’s Ratio 0.27 Fracture Toughness 1.0 x 106 N/m3/2

(µm) Index Wavelength (µm) Index 0.4047 2.54515 1.1287 2.28485 0.4358 2.48918 1.5296 2.27191 0.4678 2.44915 2.0581 2.26442 0.4800 2.43691 3.000 2.25772 0.5086 2.41279 3.500 2.25498 0.5461 2.38838 4.000 2.25231 0.5876 2.36789 4.500 2.24955 0.6438 2.34731 5.000 2.24661 0.6678 2.34033 8.000 2.22334 0.7065 2.33073 9.000 2.21290 0.7800 2.31669 10.000 2.20084 0.7948 2.31438 11.250 2.18317 0.8521 2.30659 12.000 2.17101 0.8943 2.30183 13.000 2.15252 1.0140 2.29165 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Transmission ZnS MultiSpectral Transmission - 6.3 mm thick - W avelength(/microm) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Transmission ZnS MultiSpectral Transmission - 6.3 mm thick - W avelength(/microm) 0123456789 10 11 12 13 14 15 16

Zinc Sulfide (ZnS) ZnS grown by chemical vapor deposition (CVD) at Coherent exhibits exceptional fracture strength and hardness leading to its frequent choice for military applications or other harsh environments. This material is often used in the 8 to 12 μm region. Its high resistance to rain erosion, high-speed dust, and particulate abrasion, makes it especially suitable for exterior IR windows on aircraft frames. ZnS has a lower cost relative to ZnSe and ZnS MS, and has potential wherever a tough and strong IR transmitting material is required. ZnS Material Properties All values @ 20°C Physical Properties Structure Cubic zincblende Density 4.08 g/cm3 Grain Size 2 to 8μm Inclusions None > 0.5 mm Electrical Density > 1012 ohm-cm Dielectric Constant Consult our technical staff Optical Properties Bulk Absorption Coefficient @ 10.6 µm < 0.24 cm-1 Thermo-Optic Coefficient (dn/dT) @ 10.6 µm 4.1 x 10-5/°C Refractive Index Inhomogeneity @ 0.6328 µm < 100 x 10-6 Thermal Properties Thermal Conductivity @ 20° C 0.167 W/cm/°C Specific Heat 0.469 J/g/°C Linear Expansion Coefficient @ 20° C 6.8 x 10-6/°C Mechanical Properties Young’s Modulus 74.5 GPa (10.8 x 106 psi) Rupture Modulus 103.4 MPa (15,000 psi) Knoop Hardness 210-240 kg/mm2 Density 4.08 g/cm3 Poisson’s Ratio 0.27 Fracture Toughness 0.8 x 106 N/m3/2

© 2022 Coherent Corp. Legal notices : coherent.com/legal sales@coherent.com www.coherent.com ZnS Refractive Indices Wave- length (µm) Index Wave- length (µm) Index Wave- length (µm) Index 2.6 2.260 10.6 2.192 10.6/microm 3.39/microm 1.15/microm ZnS Thermo-Optic Coefficient (dn/dT) -180 -140 -100 -60 -20 100 140 180 200 dn/dT 10 -5 °C Temper ature °C 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% Transmission ZnS Transmission - 6.3 mm thick - W avelength(/microm) 0123456789 10 11 12 13 14 15 16