Interferometric load sensor and strain gage
Abstract
The invention comprises a load sensor, or force balance, which utilizes an interferometer in place of conventional wire strain gages. A first etalon plate is positioned on a rigid fixture while the second etalon plate is positioned on a load sensitive fixture that is subject to flexure. The plates each have partially reflecting surfaces that are positioned opposite each other. It is preferred that the adjacent partially reflective surfaces of the two etalon plates are parallel within a few seconds. In a preferred embodiment of the load sensor, the air wedge gap between the two etalon plates is less than 5 seconds. When a monochromatic collimated light source is transmitted through the etalons, light fringes are produced between the two plates. The light fringes are very sensitive to the wedge angle but rather insensitive to the beam angle. Therefore, flexing of the load sensitive fixture moves the second etalon plate and results in a fringe shift. Detector means are provided for detecting shifts in the light fringes between the etalons.
- Publication:
-
patent Application Department of the Air Force
- Pub Date:
- July 1986
- Bibcode:
- 1986pad..reptT....D
- Keywords:
-
- Balance;
- Flexibility;
- Interferometers;
- Interferometry;
- Light Sources;
- Reflection;
- Strain Gages;
- Angles (Geometry);
- Loads (Forces);
- Patent Applications;
- Wedges;
- Wire;
- Instrumentation and Photography