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 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 have an anti-reflective coating which is robust: it can be cleaned with the same chemical and methods that are commonly used for precision optics.