Two methods for measuring beam diameter are described with the derivation of the equations that make them valid. These methods are the aperture method and the knife edge technique. These methods have been used for decades; however, many do not have a firm grasp of the basic equations that make the methods valid and therefore cannot use and modify the methods with confidence to produce the desired results. The text derives the equations from basic science and mathematics to clarify the underlying concepts of the methods.

The current national consensus standard for laser safety in the United States is the American National Standard for Safe Use of Lasers (ANSI Z136.1). Over the past few years, a comprehensive rewrite of this standard has been conducted. The updated version of the standard (Z136.1-2000) incorporates a wealth of new bioeffects data and establishes a number of new maximum permissible exposure (MPE) limits for laser safety. The updated standard also includes new procedures for the computation of MPE values, which must be understood by health physicists, laser safety officers, and others in the field of occupational safety. Here we present the first in a series of tutorial articles to clarify laser safety analysis procedures under this new standard. This article deals with the proper application of three rules for determining the appropriate MPE values for repetitively pulsed lasers or repeated exposures from laser beams.

Over the past few years, a comprehensive rewrite of the American National Standard for Safe Use of Lasers (ANSI Z136.1) has been conducted. The ANSI Z136.1 is a user standard, as opposed to a manufacturer standard like the Federal Laser Product Performance Standard. As such, differing philosophies for hazard classification and application of safety control measures apply, based upon the user’s perspective. Here we present the second in a series of tutorial articles designed to clarify laser hazard analysis procedures under this new ANSI Standard. The procedure presented allows the reader to effectively determine the appropriate hazard classification for a small-source laser by using known laser output parameters in a step-by-step analysis.

In this paper, we present a theoretical analysis of multiple-pulse thermal damage thresholds based on the Arrhenius integral damage model. We consider the dependence of thresholds on both the number of pulses and the pulse spacing and show that the trends can be understood by considering the thermal relaxation time. The biological data that exists in the multiple-pulse thermal damage regime fits in with the model's predictions but does not validate them. We propose a simple experiment for validation and present a hypothetical scheme for adjusting the maximum permissible exposure limit for multiple pulses in the thermal damage regime.

The current national consensus standard for laser safety in the United States is the American National Standard for Safe Use of Lasers (ANSI Z136.1). The most recent standard, Z136.1-2000, incorporates a wealth of recent bioeffects data and established a number of new maximum permissible exposure (MPE) limits for laser safety. The standard also includes recent procedures for the computation of MPE values from large or extended diffusely scattering sources, which must be understood by health physicists, laser safety officers, and others in the field of occupational safety. Here we present the fourth in a series of tutorial articles, written to clarify laser safety analysis procedures under this standard, with an emphasis on the MPE computation methods related to extended sources, and the determination of nominal hazard zones.