Optical thin film coating
Optimax Systems

Optical thin film coating is a vacuum deposition procedure used to modify the transmission and reflection properties of an optical surface. Antireflection coating and high reflection coating are the most common types of optical coatings. Beam-splitter, band pass filter, edge filter, polarizing and high laser damage coatings are also available. Certain high durability coatings can also help protect an optic surface from scratches and the environment.

Specifying Coatings
Specifying coatings begins with the desired transmission or reflection requirements of the optical components surfaces, along with the wavelength band(s) of interest and angle of incidence (AOI). Other aspects to consider when specifying coatings include polarization requirements, laser damage threshold, witness sample requirements, coating aperture and environmental requirements.

An example coating specification is given below:
* RAVG < 0.5% from 450-650nm, AOI = 0-20°, avg polarization
* Coating to withstand environmental durability requirements for Adhesion, Humidity and Moderate abrasion per MIL-C-48497A (Para 3.4.1.1-3.4.1.3). Witness sample testing is permitted, though samples are not a deliverable item.
* Laser Damage Threshold: None
* Coatings aperture is equal to the component clear aperture