Binary Zone Plate Infrared Spectrometer for Dissolved Gas Analysis in High Voltage Equipment

Abstract

An IR spectrometer based on a Binary Zone Plate (BZP) is presented for dissolved gas analysis. The wavelength selective focal length of the BZP can effectively discriminate between wavelengths ranging from 800 nm to 8 μm, by adjusting the focus distance onto an aperture in the image plane from 19 mm to 200 mm. The aperture serves to pass focused radiation onto the detector. The BZP has a focal length of 50 mm for a design wavelength of 3 μm, with 400 zones. This design enables discrimination between all key fault gases present in oil impregnated high voltage equipment.