ANSI/IES LM-72 Directional Positioning of Photometric Data

This document is intended to provide a clearly defined set of terms to be used to designate the angular positioning of photometric data. The terms are intended to be used by both providers and users of lighting software so as to unambiguously and consistently specify how photometric data is to be “rotated” before it is used. Two similar but fundamentally irreconcilable types of positioning have existed for years. The “Clockwise from North” (“CN”) system starts by rotating luminaire photometric data clockwise from north. The “Counter-Clockwise from East” (“CCE”) system starts by rotating luminaire photometric data counter-clockwise from east. A third positioning method, called “aiming luminaire at a point,” has also existed for years and is also discussed in this document.

LISUN following instruments fully meet ANSI/IES LM-72 Directional Positioning of Photometric Data:

LMS-6000 Portable CCD Spectroradiometer

LSG-2000 Goniophotometer with Rotating Mirror

LSG-1890B High Precision Rotation Luminaire Goniophotometer

LSG-1700 Rotation Luminaire Goniophotometer

LSG-1200A Compact Goniophotometer

LSG-1900B Near Field Moving Detector Goniophotometer