Radiometric apertures

The essential part of a filter radiometer is precision aperture which is used to determine the amount of irradition entering the device. The knowledge about the diameter of the aperture contributes directly to the uncertainty estimate of optical radiometric measurements. The quality of an aperture, in turn, depends on the machining process.

The precision apertures for filter radiometers can be manufactured in several ways: by using ordinary milling techiques or diamond turning. The choise of the manufacturing technique depends on variety of factors: material, desired diameter of the aperture, edge thickness of the aperture, surface finish and coating ao.

The calibration of the manufactured aperture gives an estimate for the choice of the aperture desing and the manufacturing. Also, for calibration of an aperture several measurement methods can be applied. Amongst the others, the popular methods are based on laser beam scanning technique and video measuring machines... Click to open full document as pdf file