When measuring the form errors of precision optics with an interferometer, calibration of the reference wavefront is of central importance. In recent years, ball averaging, or random ball testing, has emerged as a robust method for calibrating spherical reference wavefronts in converging beams.
Calibration of Interferometer Transmission Spheres
Robert E. Parks Precision Machining Research Facility, NIST
This paper describes an inexpensive, quick and self-consistent method of calibrating spherical transmission optics where there is a real focus of the diverging test beam outside the transmission optic. The method is self-consistent in the sense that any given test result provides a means of calculating the variance of the result and requires no additional optic that must be calibrated or traced to another standard.
Davidson Optronics, Scratch & Dig Samples
Inspecting and characterising surface quality of finished optical components e.g.: lenses, prisms, mirrors, reticles, windows and wedges in accordance with MIL-13830, MIL-C-48497 and the new ANSI/OEOSC OP1.002:2008 is easily accomplished using these scratch & dig sample sets. The samples serve as direct visual comparison standards.
Each set consists of ten individual samples in a fitted hardware case. Samples are hermetically sealed as stand-alone pieces with a size of 1.5 x 1.5 x 0.375 inch (38 x 38 x 10 mm)
Values are: Scratch 10 – 20 – 40 – 60 – 80 | Dig: 5 – 10 – 20 – 40 – 50
Order set D-667, or D-667A, for a set with half-aluminised scratch samples (useful for characterizing highly reflective and/or polished metal surfaces).
Conforms to ANSI/OEOSC OP1.002:2008
Certificate of Calibration Supplied
Compliant to MIL-O-13830 Rev. L
Please also review a portable illumination cabinet from Armstrong Optical to compare standards and your samples – Cabinet link
For more information please call Armstrong Optical (+44 (0)1604 654220) or CLICK HERE