Laser hazard classification of a line laser with an astigmatic extended source

Abstract

Since lasers are used in a large variety of applications, new laser products have become more complex. To increase performance, like range or brightness, it is important to consider the maximum optical output that will not exceed laser safety limits. Exposure to an extended source laser results in a larger retinal image and a simplification of treating it as a point source unnecessarily restricts system performance. For laser beams where the location of the apparent source (beam waist) is different in each axis (astigmatic beams), the retinal image is asymmetric and is also a function of eye accommodation. Lasers with astigmatic beams are often evaluated as point sources because accommodation on the source in either beam axis can indicate that the source in that axis is a point source; however, the eye can only focus (accommodate) on one distance at a time. For a single accommodation of the eye, the source may be extended, and extended source lasers are considered less hazardous than point source lasers of the same output power because of the reduction of retinal irradiance (the power is distributed over a larger area). For a line laser with an astigmatic beam, a particular laser hazard class may allow for a higher laser output power than would be allowed if it were a point source laser.