The intent of this IES document is to describe measurement procedures for the determination of the luminous intensity distribution of certain lamps and luminaires, using a digital camera to capture the projected light distribution from a luminaire onto a screen. Many factors need to be taken into account to achieve accurate digital photometry; this report addresses the most significant of these factors. Because this is a relatively new technique, considerable detail is provided to assist the reader in understanding the principles, requirements, and limitations involved. This document addresses the use of digital cameras incorporating a CCD array. Requirements for accuracy and the special conditions for this form of light measurement are covered. The numerous factors to be taken into account for hardware selection and software development are described. Calibration requirements are specified, as are data reduction techniques.
Page count: 34 pages
Publisher: Illuminating Engineering Society (2020)
SKU: ANSI/IES LM-77-20
1.0 Introduction and Scope
2.0 Background and Basic Principles
3.0 Test System Geometry
4.0 Angular Resolution
5.0 Stray Light
6.0 Specification of the Digital Camera
7.0 Linearity Verification and Useable Range
9.0 Test Procedure
10.0 Data Reduction and Test Report
Illuminating Engineering Society. ANSI/IES LM-77-20, Approved Method: Intensity Distribution Measurement of Luminaires and Lamps Using Digital Screen Imaging Photometry. New York: IES; 2020.