Kinematic Mount Selection for Optical Scanning Assemblies
Kinematic mount selection for optical scanning assemblies isolates substrates from thermal and dynamic distortions while maintaining sub-microradian repeatability.
Mirror Surface Flatness
Meaning
Deviation of a reflective surface from an ideal plane measures the quality of an optical component used in beam steering or imaging. Mirror surface flatneess is usually specified in fractions of a wavelength, such as lambda over ten, measured across the clear aperture. It determines the amount of wavefront distortion introduced into the optical path.
Interferometric Measurement
Inspection of the optic using a Fizeau interferometer provides a topographic map of the surface errors. High mirror surface flatness prevents the blurring of the laser spot in high resolution lithography. These measurements are taken after the coating process to ensure that film stress has not warped the substrate.
Mounting Strain
Distortion can be introduced when the mirror is clamped into its housing. Mechanical stress from a poorly designed mount often degrades the mirror surface flatness far more than the manufacturing process did. Using low stress adhesives or kinematic mounts preserves the original quality of the optic.
Surface Quality
Roughness and local slopes affect the scattering of light and the power density at the focal point. While flatness covers long range form, these micro features impact the efficiency of the laser system. A production run is audited against these specifications to prevent the use of substandard glass.