Simple Pulse Width Modulation (PWM) LED Source for Linearity Testing of DSLR Camera Sensor (Abstract)

Volume 39 number 1 (2011)

Helmar G. Adler

40 Mohawk Street, Danvers, MA 01923; eagle.astro@gmail.com

Abstract

(Abstract only) To create meaningful photometry data knowledge of the linearity performance of the sensor in use (e.g. CCD or CMOS-array) is essential. The emergence of embedded controllers makes it possible—even for the hobbyist — to build fairly low-cost, highly controlled devices with capabilities that can be utilized to make light sources with pulse-width modulated LEDs. A simple system, comprised of a laptop computer, an embedded controller with an LED, and a few additional parts will be shown. Experiences and data regarding linearity testing of the source itself and, subsequently, characterization of a Canon DSLR camera with the source, will be shown. The technique can easily be extended to other sensors. The camera is currently used to take photometry data of epsilon Aurigae.