Gas monitors
AssigneeEEV Limited
InventorsMichael Parry, Alan Mason Doncaster
Life of this patent
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Abstract
A gas monitor includes an infra-red source enclosed within a housing having inner surfaces which are reflective. Radiation emitted from the source reflects off ellipsoidal surfaces and intermediate planar surfaces to be focussed at a sensor, being reflected five times. Radiation is absorbed by gas within the housing and a comparison of the source intensity and detected intensity gives a measure of the gas concentration. Use of ellipsoidal reflective surfaces directs emitted radiation along a plurality of routes having substantially the same path length, hence giving an accurate measure of the gas concentration with a compact device. In another embodiment, off axis parabolas are used to direct the radiation through the gas.
Claims14
A gas monitor comprising:
- an optical source;
- a sensor sensitive to light from said source;
- a chamber containing gas to be monitored;
- and reflector means having reflective surfaces in said chamber and having foci;
- said source and sensor being located within said chamber and being substantially at said foci and light from the source being reflected at least three times at said reflective surfaces before reaching said sensor.
Dependencies are inferred from the claim text.