Encoder, Grating, High Resolution
Sunday, September 03, 2006
A High Resolution Angular Encoder has been designed and developed that contains a polygonal mirror wheel mounted to a shaft. A Binary or Gray code reader reads a Binary or Gray code pattern on the wheel. This indicates the shaft coarse resolution angle to within the increment of angle subtended by one side of the polygon. The output of the reader identifies which side of the polygon lies along a given line of sight.
A Laser sends a narrow, low divergence laser light beam of monochromatic light toward the polygonal mirror wheel. One of the mirror facets reflects the laser light beam onto a nearby low line density diffraction grating.
The laser light beam diffracted from the grating strikes a linear array of photodetector at several locations. The outputs of the photodetectors are digitized, providing fine resolution data on the distribution of light diffracted onto the photodetector array. This data is fed to a microprocessor for calculation of the shaft angle.
Source: “High-Resolution Optoelectronic Shaft-Angle Encoder”, Laser Tech Briefs, Vol. 2, No. 2, Spring, 1994, page 32.
Reference:
1) Goddard Space Flight Center, Reference numbers GSC-13611 and GSC-13543
2)Douglas B. Leviton, Goddard Space Flight Center
Industrial Products
posted by JD52 @ 12:50 AM,
