Glossary of Symbols and Acronyms

Introduction

Infrared Optics

Applications of Infrared Optics

Material Properties

Index of Refraction

Index of Refraction Measurement

Temperature Coefficient of the Refractive Index

Dispersion

Birefringence

Transmission

Absorption

Atmospheric Absorption

Infrared Atmospheric Windows

SWIR

SWIR Images

MWIR

MWIR Images

LWIR

LWIR Images

Transmission of Infrared Optical Materials

Mechanical Properties

Hardness

Solubility

Thermal Properties

Thermal Runaway

Crystal versus Glass

Crystallographic Properties

Periodic Table

Material Classifications

Material Legend

Semiconductors

Semiconductors

Cadmium Telluride, CdTe

Gallium Arsenide, GaAs

Germanium, Ge

Silicon, Si

II-VI Crystalline Compounds

II-VI Crystalline Compounds

Zinc Selenide, ZnSe

Zinc Sulfide, ZnS

Zinc Sulfide, ZnS, Clear Grade

Alkaline Earth Halides or Fluorides

Alkaline Earth Halides or Fluorides

Barium Fluoride, BaF₂

Calcium Fluoride, CaF₂

Lithium Flouride, LiF

Magnesium Fluoride, MgF₂

Oxides

Oxides

Fused Silica, IR Grade

Magnesium Oxide, MgO

Sapphire, Al₂O₃

Alkali Halides

Alkali Halides

Cesium Iodide, CsI

Potassium Bromide, KBr

Potassium Chloride, KCl

Sodium Chloride, NaCl

Thallium Bromoiodide, KRS-5

Other Materials

Irtran Materials

Other Materials

Amorphous Materials

Chalcogenide Glasses

Chalcogenide Glass Overview

As₄₀Se₆₀

Ge₁₀Se₅₀As₄₀

Ge₂₈Sb₁₂Se₆₀

Ge₃₃Se₅₅As₁₂

Chalcogenide Trade Names

Custom Chalcogenide Glasses

Material Fabrication

Crystal Growth

Bridgman–Stockbarger Technique

Czochralski Technique

Kyropoulos Technique

Chemical Vapor Deposition

Sintering and Hot Pressing

Hot Isostatic Pressing

Float Zone

Sapphire Growth Techniques

Sapphire Growth Techniques – GSM

Sapphire Growth Techniques – HDSM

Sapphire Growth Techniques – HEM

Chalcogenide Glass Melting

Process Chains for the Manufacture of Infrared Optics

Optical Fabrication

Conventional Grinding and Polishing

Double-Side Polishing

Continuous Polishing

CNC Grinding and Polishing

Grind and Polish Process Chain

Single-Point Diamond Turning

SPDT Process Chain

Precision Glass Molding

PGM Process Chain

Manufacturing Process Chain Comparison

Thin Film Coating

Single-Layer Antireflective IR Coatings

Multilayer Antireflective IR Coatings

Diamond-Like Carbon / Hard Carbon Coatings

Infrared Material Pricing

Applications

Applications: Pressure Windows

Applications: Commercial Thermal Imaging

Applications: FTIR Spectrophotometry

Applications: Athermalized IR Lens Assemblies

Applications: Quantum Cascade Lasers

Appendix A: Material Property Comparisons

Density

Melting Point

Modulus of Rupture

Shear Modulus

Specific Heat Capacity

Thermal Conductivity

Thermal Linear Expansion

Young's Modulus

Knoop Hardness

Refractive Index at 3 μm

Refractive Index at 10.6 μm

Appendix B: General References by Topic

Appendix C: Chalcogenide Glasses

Equation Summary

Bibliography of Further Reading

Index

The authors' purpose in writing the Field Guide to Infrared Optical Materials was to create a concise, efficient reference for the quick analysis of commonly used infrared optical materials to aid in their review for selection. The emphasis has been placed on practicality. The collection of materials is based on the authors' experience of which materials, processes, and procedures are commonly used in the industry today. There are certainly many other infrared optical materials available on the market and there are much more detailed and comprehensive references for this sort of information. The authors would suggest the excellent references by Klocek, Weber, and Wolfe or any of the other books listed in the bibliography. It is also highly recommended that, prior to final selection of a material, a detailed study is undertaken and direct contact is made with the specific material manufacturer for any required material properties (see disclaimer).

The authors would like to thank the following individuals for their assistance in writing this guide: Matthew Brown, Jacklyn Novak, Dr. Bill Moreshead, and Erik Stover at M3 Measurement Solutions and John Burnett at NIST for assistance with the page on measurement of the index of refraction. A special thanks to Jeff Richling and Myeong Nam for their substantial help with the coating section and to Pavel Reshidko and Ran Carmeli at RP Optical for the excellent images. This work would not have been possible without the support of the exceptional team at LightPath Technologies and ISP Optics.

This guide is dedicated to my family: Lauren, Carter, Cooper, and Holden. I could never have imagined to be so lucky to have a family like this! A.S.

This guide is dedicated to my family: Erenn, Donna, Boris, David, and Daniel. Love you all. M.L.

Alan Symmons
Mark Lifshotz
July 2021