optical polishing comparison

For ring laser gyroscope (RLG) mirrors, R&D applications, short wavelength and ultrafast lasers, superpolishing offers significantly superior performance compared to products from other optics manufacturers. G&H’s process delivers Scratch-Dig of 5-2, less than 0.5 Å of surface roughness, and zero defects at 300x magnification.

Most superpolished optics are supplied with polished or acid-etched outside diameters and bevels. These extra refinements add to the level of cleanliness and durability of the components. Superpolished materials include N-BK7, calcium fluoride, crystal quartz, fused silica, sapphire, silicon carbide, YAG and Nd:YAG, and ZERODUR®

Sapphire Polishing

Sapphire is a unique material well suited for many ultraprecision optical applications. It is transparent from the lower UV (142 nm) through the midwave infrared (6.5 µm). Its high tensile strength makes it well suited to many high g-force environments. In addition, sapphire is very tolerant of high radiation environments, such as spacebased applications. Due to its high mechanical strength, sapphire is a very difficult material to polish. Our unique superpolishing processes allow us to polish sapphire components to better than 1 Å surface roughness.

Silicon Carbide

Silicon carbide (SiC) is often used in the optics industry to replace components previously manufactured out of beryllium. The material offers a viable alternative with low weight, high specific stiffness, high thermal conductivity and excellent dimensional stability. We have developed expertise in polishing silicon carbide mirrors, and can polish CVD SILICON CARBIDETM and lightweighted versions of this material.

G&H also offers customer-supplied substrate polishing services. Additionally, we offer SiC cladding with IBS coatings to ensure the finest possible final surface finish. Lastly, we also supply optical coatings on the finished mirror.

G&HCompetitor ACompetitor B
Surface Roughness (RMS)<0.5Å<1Å<0.5Å
Scratch Dig<5-210-5Not specified
Inspection magnification for defects300x20x100x
Surface accuracy<lambda/50<lambda/10<lambda/20
ShapesFlat, Curved, multiple surfacesFlatFlat, Curved, multiple surfaces
MaterialsSi, SiC, Sapphire, Zerodur, BK7, Fused Silica, Crystal Quartz, YAG , CaF2, Quartz, YAG, LuAg and others.Fused SilicaFS, BK7, Zerodur and others
Table 1 Comparison of 3 “super-polish” provider
For more information on our superpolished optics, please contact us.