Automatic Focusing System.
Abstract
An automatic focus control system for a camera lens wherein a laser head for generating a pair of orthogonally polarized coherent beams of different angular frequencies is adapted to provide a periodic reference signal at a frequency equal to the frequency differential of the beams. An electro-optics assembly translatably mounted intermediate the laser head and the lens for detecting optical path length changes of one of the beams directed through the lens along the optical axis thereof varies the image distance to a fixed image plane in accordance with changes in the location of the focal plane. The electro-optics assembly includes an interferometer optically connected to the laser head for spatially separating and recombining the beams, an optical receiver coupled to the interferometer for receiving the recombined beams and producing therefrom a periodic measurement signal the phase of which is indicative of the optical path length difference of the recombined beams, and a plane mirror angularly disposed along the optical axis for projecting an object image upon the image plane.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 17, 1979
- Accession Number
- ADD006953
Entities
People
- Thomas Glavich
Organizations
- United States Department of the Navy