发明名称 |
Infrared laser detector employing a pressure controlled differential optoacoustic detector |
摘要 |
An infrared laser absorption spectrometer is disclosed wherein a pair of detector cells are disposed serially along the laser beam path. The laser beam is modulated to produce a modulation of the absorption by the sample materials in the two cells. Modulated absorption by the samples produces an acoustic wave in each cell which is detected by a suitable microphone and subtracted so as to produce a difference signal corresponding to the difference in infrared absorption between the two cells so that undesired background effects common to both cells are cancelled. A pressure controller, which is responsive to the pressure difference between the sample pressure in the two cells at a frequency substantially below the beam modulation frequency is employed for controlling the pressure differential. In one embodiment the pressure controller includes a compliant membrane partitioning the two cells so that the membrane may move so as to equalize the pressures. In a second embodiment, deflection of the diaphragm of a differential microphone coupled into both cells is employed to derive an output utilized to control either the flow through the cells and/or the volume of the respective cells to control the pressure difference between the cells.
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申请公布号 |
US4019056(A) |
申请公布日期 |
1977.04.19 |
申请号 |
US19750572013 |
申请日期 |
1975.04.28 |
申请人 |
DIAX CORPORATION |
发明人 |
BLOCK, BARRY;AINE, HARRY E. |
分类号 |
G01N21/17;(IPC1-7):G01J3/42 |
主分类号 |
G01N21/17 |
代理机构 |
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代理人 |
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主权项 |
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地址 |
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