How do you clean a CGH?

AOM CGHs are binary grating patterns printed on 1/4″ thick fused silica substrates.

The patterned side of the CGH is either a chrome-on-glass grating (amplitude type CGH) or etched glass steps (phase-type CGH) of sub-µm depth and µm-scale pitch. The patterned side of both CGH types is robust and can be cleaned with common precision optics cleaning methods and chemicals.

• • It is recommended to clean the patterned side of the CGH using a clean optical wipe with isopropyl alcohol, methanol, or acetone.
  • The “drag” method is a recommended first step – a clean wipe with the desired cleaning solution is dragged slowly across the surface.
  • Light pressure with a circular motion with a clean optical wipe and chemical solution is also acceptable and will not damage the pattern.

 

The back side of most CGHs has an anti-reflective coating which is robust: it can be cleaned with the same chemical and methods that are commonly used for precision optics.