초록 ▼

A multi-component non-dispersive gas analyzer of a type typically used to measure the concentrations of gases present in automotive emissions and in breath analyzers has no moving parts and employs electrically operated means for effectively inserting and removing a reference cell from the optical p

A multi-component non-dispersive gas analyzer of a type typically used to measure the concentrations of gases present in automotive emissions and in breath analyzers has no moving parts and employs electrically operated means for effectively inserting and removing a reference cell from the optical path and for selecting a particular filter to determine momentarily the wavelengths of radiation being examined. The means for accomplishing these ends include a substrate on which a layer of vanadium dioxide is deposited. The layer is a good reflector at temperatures greater than 67°C. and reflects only slightly at lower temperatures. The layer is alternately heated by an electrical current and is then allowed to cool to provide the desired optical switching action. This electrically-controlled selectively reflective layer is then used in conjunction with the reference cell and with an array of filters to implement the necessary switching and selection of the components.

대표청구항 ▼

Apparatus for use in an analyzer and characterized in having no moving parts, for, in effect, alternately including a reference cell in a beam of radiation and removing the reference cell from the beam of radiation, the reference cell having a window for permitting the beam of radiation to enter the

Apparatus for use in an analyzer and characterized in having no moving parts, for, in effect, alternately including a reference cell in a beam of radiation and removing the reference cell from the beam of radiation, the reference cell having a window for permitting the beam of radiation to enter the reference cell, said apparatus comprising in combination: a layer of a material that has selectably a highly-reflective state and a highly-transmissive state, positioned in the beam of radiation ahead of the reference cell so that the beam of radiation is reflected from said layer when said layer is in its highly-reflective state and is transmitted by said layer when said layer is in its highly-transmissive state; means for reflecting the radiation that has been transmitted into the reference cell back out through the window, so that when said layer is in its highly-transmissive state the beam of radiation is passed back through said layer; means for alternating the state of said layer between the highly-reflective state and the highly-transmissive state; means for collecting the total radiation reflected from said layer and emerging from said layer; and, means for comparing the total radiation collected when said layer is in the highly-reflective state with the total radiation collected when said layer is in the highly-transmissive state.