Optical Materials
Inrad Optics draws on a broad portfolio of optical materials, including crystals, metal alloys and polymers. Here’s an overview of those materials and their applications:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
AlBeMet mirrors offer a low cost alternative to beryllium while maintaining significant strength properties when compared to aluminum. AlBeMet optics are primarily nickel-plated for precision diamond turning and polishing operations.
Mirrors made from aluminum have an important production advantage: They can be diamond turned directly without any plating, minimizing optical distortion in athermal environments. Alternatively, they can be nickel-plated and polished when surface roughness must be kept to a minimum.
Beryllium mirrors can be polished bare, or can be nickel-plated, diamond turned and polished to very accurate prescriptions. Beryllium substrates provide extremely high stiffness-to-weight ratio and are ideal for fast steering mirrors, and extreme environments in space, airborne and ground applications.
Beryllium Copper mirrors are fabricated in a similar manner to non-alloyed beryllium, when the mechanical and heat absorption properties of beryllium copper are desired.
CaF2 is a synthetically grown, cubic crystal with an effective transmission range extending from 300nm through 9000 nm, making it an excellent material for broadband UV through Mid-Wave IR applications. Optical elements such as lenses, windows and prisms can be manufactured in sizes exceeding 100mm.
Copper mirrors provide excellent thermal absorption and are frequently used for high laser energy applications. Ultra-high purity oxygen-free copper may be direct diamond turned to very accurate prescriptions then coated with either electrolytic gold or various evaporative materials.
Fused Silica is an amorphous glass that is almost pure Silicon Dioxide (SiO2). Raw material manufacturers employ several manufacturing techniques and unique processes, resulting in specific compositions that have unique wavelength transmission and material homogeneity properties. Fused Silica is a very hard and durable material, resistant to many chemicals and toxic environments. It can survive wide temperature fluctuations. Various compositions and trade name acronyms are available, including Homosil, Infrasil, Suprasil, 7940 and 7980. Blanks are commercially available in large sizes.
Germanium is a synthetically grown, cubic crystal with an effective transmission range extending from 2000nm through 14000nm, making it an excellent material for applications ranging from the Near-IR into Far-Wave IR. Optical elements such as lenses, windows and mirrors can be manufactured in sizes in excess of 150mm.
InSb is a sintered crystal that can be fabricated into disc and prismatic forms. Though it is not single crystal, surfaces can be polished to optical grade mirror finishes. Optical elements are typically used in Near-IR to Mid-Wave IR detection applications.
Ultra-Low Expansion (ULE), Zerodur and ClearCeram and other low-expansion ceramic glass materials have low coefficients of thermal expansion, allowing them to remain stable over wide temperature ranges. These materials exhibit good homogeneity, chemical resistance and manufacturability. Material blanks are available in very large sizes. They are often light-weighted with a honeycombed back-surface. Low-expansion ceramic glass is often fabricated into mirror elements for applications such as telescope and interferometers.
MgF2 is a synthetically grown, tetragonal crystal with an effective transmission range extending from 157nm through 6000nm, making it an excellent material for applications ranging from deep UV into Mid-Wave IR. Optical elements such as lenses, windows and prisms can be manufactured in sizes up to 100mm.
This "catch-all" category of various constituent elements can often be polished as a bare alloy. Or it can be nickel plated, diamond turned, and polished to very accurate prescriptions. The applications of metal matrix composites vary widely and are related to the properties of primary optical materials used within the composite.
This soft alkaline material may be direct diamond turned. It is frequently used as an intermediary material between optics and structures due to its ability to mitigate assembly stresses.
Nickel mirrors can be polished bare or can be nickel-plated diamond turned and polished to very accurate prescriptions. Bare polished nickel surfaces may be coated with either electrolytic gold or various evaporative materials.
There are several designations of glass types, with each glass code having its own unique Refractive Index & Abbe number, transmission characteristics, temperature handling capability, and abrasion durability. Crown and Flint glasses are used in the manufacture of elements such as prisms, lenses and windows. Crown glasses have refractive indices near 1.5, whereas Flint glasses have indices near 1.7. Glass selection is critical in designing optical elements used in correction of system aberrations and distortions. Various optical filter glass compositions are available for absorbing light in one wavelength spectrum while transmitting light in another spectrum. Rare-earth specialty glasses are used in manufacture of active laser elements.
Acrylics, polycarbonates and other optically-useful polymers are employed in lower-cost optical applications, including molding of complex geometries at minimum per unit machining cost. Most hard polymers may be direct diamond turned.
This very high hardness crystalline material may be ground and polished to very accurate plano & spherical optical prescriptions.
Silicon is a synthetically grown, cubic crystal with an effective transmission range extending from 1200nm to 7000nm, making it an excellent material for applications ranging from the Near-IR into Mid-Wave IR. Optical elements such as lenses, windows and mirrors can be manufactured in sizes in excess of 150mm.
Silicon carbide is used as an alternative to beryllium when a high strength to weight ratio is desired. SiC can be polished bare or can be nickel-plated, diamond turned, and polished to very accurate prescriptions.
Stainless Steel can be polished bare or can be nickel-plated diamond turned and polished to very accurate prescriptions. 17-4 Stainless steel is the preferred alloy for optical applications.
Unlike fused silica, quartz is a birefringent material, enabling it to be used in manufacture of wave plates, beam splitters, retarders and other polarizing optical elements. Synthetic quartz has a large optical transmission window-from 200nm through 6000nm. It is a hard, durable material. Blanks are available in various orientations, sizes and homogeneities. Synthetic quartz allows finished component sizes in excess of 100mm diameter.
Titanium optics are typically used in high temperature environments and can be polished bare or can be nickel-plated diamond turned and polished to very accurate prescriptions.
Transmissive crystalline materials
Germanium, zinc sulfide, zinc selenide, ClearTrans, silicon and other "soft" crystals may be ground & polished into windows and domes with high very accuracy. Spheres and aspheres can also be fabricated using diamond turning operations.
Tungsten copper, Thermcon 83 being a common example, is usually employed in structural applications. It can be electroless nickel and electrolytically gold plated.
ZnSe is a synthetically grown, cubic crystal with an effective transmission range extending from 800nm through 20000nm, making it an excellent material for applications ranging from the Near-IR into Far-Wave IR. Optical elements such as lenses, windows and mirrors can be manufactured in sizes in excess of 150mm.
ZnS is a synthetically grown, cubic crystal with an effective transmission range extending from 500nm through 15000nm, making it an excellent material for applications ranging from the Near-IR into Far-Wave IR. Optical elements such as lenses, windows and mirrors can be manufactured in sizes in excess of 150mm. Cleartran is a trademark name manufactured by one specific supplier using a proprietary CVD growth process that results in high material homogeneity.