| 摘要 |
Optical phenomena known as frustrated and attenuated total internal reflection are used to measure pressure. Light is beamed into a thin glass plate (22) via an optical fiber (18). The internally reflected light beam is carried to a photocell (28) via a second optical fiber (20). A diaphragm (12), which may be integral with a pressure vessel, is mounted next to the plate (22) and deflected under pressure. As the diaphragm (12) approaches the glass plate (22), the amount of light reflected decreases. In the preferred embodiment, a boss (12b) on the diaphragm (12) is evenly coated with a soft, highly reflected metal such as gold to induce attenuated total reflection. The gold is flattened by overpressuring the exposed side of the diaphragm (12) and forcing the boss (12b) and the glass plate (22) together. The change in the amount of reflected light is translated into an analog electrical pressure signal. The optical transducer is resistant to the hostile environment of internal combustion engines because of its insensitivity to electromagnetic interference, vibration and thermal transients. |
