Pressure measuring device for corrosive laser gas - uses monochromatic light source in gas absorption band and photodetectors illuminated directly and via gas, supplying signals to processor

摘要

The arrangemnt is used for gases in which the absorption spectrum contains at least one band. A generator emits monochromatic light whose wavelength is inside the absorption band of the gas. A sensor measures the beam transmitted through the gas and a reference sensor measures directly the beam emitted by the generator. Both sensors are connected to a processor which calculates the ratio between the energy of the reference beam and the energy of the transmitted beam. This ratio represents the gas pressure. A converging lens and a diaphragm are placed between the light generator and the gas and a band-pass interferential filter after the gas. The lens and diaphragm may be mounted on a coaxial tubular support separate to another on which are mounted the filter and receiver. Between the two supports, and perpendicular to their axes is situated a cylindrical transparent tube containing the gas.