Lidar, an acronym for Light Detection and Ranging, is a laser radar which can be used to measure the opacity of particulate emissions from stationary sources. Extensive test results support the promulgation of the lidar technique as an alternate method to Reference Method 9, that uses trained visible emissions observers. Three tests demonstrate lidar precision and accuracy: one using an aerosol chamber to generate a controlled particulate plume, the second using an optical generator to simulate lidar return signals, the third using fabricated screen targets of constant fixed opacity. Correlation of lidar opacity values and visible emissions observations was measured by the Lidar - Reference Method 9 Collaborative Test. The Colorado Smoke Generator Test correlated lidar opacity with a calibrated in-stack transmissometer. Advantages of lidar over VEOs are the ability to measure opacity during darkness and independently of background contrast conditions, and also the lidar is not subject to time and endurance constraints. Requirements and procedures needed to facilitate routine use of lidar were developed. Twelve tables, 65 figures. Appendix A - Standards of Performance for New Stationary Sources. Appendix B - Omega 1 Lidar: Computer Software. References.

Includes bibliographical references (pages 177-180). "July 1981." "EPA-330/1-79-003-R."