Aperture area metrology using confocal laser beam scanning technique

In precision optical radiometric and photometric measurements, one of the limiting factors is an accurate knowledge of the area of a beam limiting aperture. The world´s most accurate radiometric measurements are currently realized with a relative standard uncertainty of order 10^-4. To achieve this level of accuracy it is essential to measure apertures with the same relative standard uncertainty. We present a computer controlled absolute aperture-area measurement system based on a confocal laser beam scanning technique. In this system, a precision aperture is scanned utilizing a tightly focused beam and precision translation stages.