Method and apparatus for measuring incident light angle relative to level
US4988193A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 1, 1989 |
| Grant date | Jan 29, 1991 |
| Priority date | — |
| Expiry date | Mar 1, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01C15/002
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus operable in accordance with the method of the present invention for measuring the angle of incidence of a light beam or plane relative to level comprises a photodetector array for sensing the light and a level mirror preferably comprising a pool of mercury. Optics are provided for transmitting the light to the photodetector array in alignment with the angle of incidence of the light (aligned light) and also after the light has been reflected from the mercury pool (reflected light). A shutter is provided for separating aligned light from reflected light such that distinct signals representative of the two are generated by the photodetector array. The distinct signals are processed by up-counting and down-counting a counter circuit to determine the average centers of light spots representative of the aligned light and the reflected light and the distance between those average centers which is representative of the deviation of the light beam or plane from level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.