Eye safety classification of a diode laser rangefinder

Due to unsymmetrical irradiance pattern of most diode lasers combined with inherent astigmatism diode laser based devices are not trivial to classify. In absence of non-standard collimation optics such as cylinders, wedges, special fibres etc. used to reduce inherent astigmatism and to circularize the laser beam, cross section geometry of such a collimated beam may vary substantially going from near field to far field.

This adds to complexity of classification procedure in the following manner:

• angular subtense has to be evaluated at several distances in front of the device and

• radiant exposure in the near field doesn’t necessarily behave as a uniform function of increasing distance from the device