Abstract

This paper describes a relatively simple system for detecting in-focus objects. A nonlinear, wide-area photocell with parallel-plate electrodes is vibrated axially behind a lens. When the object is out of focus, the photocell conductance varies at the vibration frequency. When the object is in focus, the photocell conductance signal “folds over” because of the symmetry about the image plane. This “fold over” is detected by electronic circuitry. The scheme is shown to operate over a wide field of view, and the photocell conductance as a function of axial position is given for a number of idealized object patterns. An experimental unit built on these principles is described briefly.

© 1964 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
Phenomena of Image Sharpness Recognition of CdS and CdSe Photoconductors

Paul Pargas
J. Opt. Soc. Am. 54(4) 516-519 (1964)

Wavefront Reconstruction with Diffused Illumination and Three-Dimensional Objects*

Emmett N. Leith and Juris Upatnieks
J. Opt. Soc. Am. 54(11) 1295-1301 (1964)

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Cited By

You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Figures (10)

You do not have subscription access to this journal. Figure files are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription

Equations (16)

You do not have subscription access to this journal. Equations are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
or
Login to access OSA Member Subscription