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Proceedings Paper

High-definition illuminated table for optical testing
Author(s): Michael Schulz; Egbert Buhr; Kai Marholdt; Winfried Willemer; Detlef Bergmann
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Paper Abstract

An illuminated table intended for illuminating transmission test charts used for the optical testing of different image capture devices has been developed. It provides a diffusely luminous table face, 300 mm in diameter, in a compact set- up. The spectral distribution of the emitted light is similar to Planck radiation of about 3050 K as required, for example, for testing, digital photographic cameras. The luminance level achievable is about 15000 cd/m2, the standard deviation of which is 1.8 percent within a circle of 300 mm in diameter. The illuminated table consists of an integrating hemisphere, with the large opening covered by an opal glass serving as the illuminated table face. Inside, a set of seven tungsten lamps is posited at locations such that the light output at the table face is as uniform as possible. Residual non-uniformities caused, for example, by slightly differing luminous intensities of the lamps are adjusted by controlling the currents of the seven lamps individually by means of a PC-controlled automatically running optimization process. This closed control loop uses a calibrated digital camera to capture the current spatial light distribution at the table face. The image is analyzed by an algorithm integrated in to the control loop.

Paper Details

Date Published: 6 September 1999
PDF: 10 pages
Proc. SPIE 3739, Optical Fabrication and Testing, (6 September 1999); doi: 10.1117/12.360185
Show Author Affiliations
Michael Schulz, Physikalisch-Technische Bundesanstalt (Germany)
Egbert Buhr, Physikalisch-Technische Bundesanstalt (Germany)
Kai Marholdt, Physikalisch-Technische Bundesanstalt (Germany)
Winfried Willemer, Physikalisch-Technische Bundesanstalt (Germany)
Detlef Bergmann, Physikalisch-Technische Bundesanstalt (Germany)


Published in SPIE Proceedings Vol. 3739:
Optical Fabrication and Testing
Roland Geyl; Jonathan Maxwell, Editor(s)

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