| 摘要 |
<p>A micromachined integrated opto-thermal sensor having a rapidly intensity varying or pulsing light source, and interference filter, shadow masking or reflective blocking of light from thermal sensors, or differential operation, a gas cavity into which the detected gas can flow into via a channel or filter, and thermal detector elements to sense the heating of the gas caused by the absorption of light at a particular wavelength by the specific gas to be detected. Another version of the sensor is one with a dual cavity. One cavity contains the gas to be detected and the other cavity is sealed from the ambient environment and contains no gas. Signals from the detectors from the cavities are subtracted from each other resulting in the elimination of a fixed signal due to radiation impinging the detectors. A ratio of the signal from the detectors may be calculated for determining a presence of gas or fluid. The detector may have only a single cavity with two groups of thermal sensors. Each group of sensors receive radiation filtered by an interference filter which passes radiation of one wavelength for one group and of another wavelength for the other group. A ratio of the resultant signals from the two groups of thermal sensors, respectively, is calculated to determine the presence of gas in the near ambient environment of the detector.</p> |
