There are CDRH standards that define laser safety categories in terms of risk to humans. These standards also define test setups so that such safety categories are objective and can be universally understood and applied.
Ophir offers power sensor accessories for those involved in such measurements. These include apertures of 7 mm diameter (the “standard” pupil diameter in darkness) and 3.5 mm (the “standard” pupil diameter in daylight) for use with Ophir’s “PD300” family of photodiode sensors.
The PD300RM-UVA has a 2.75 mm aperture that allows better mapping of the irradiance uniformity of wide beams and also permits measuring higher irradiance and dosage levels than its siblings (up to 15 W/cm2). Due to a unique diffuser geometry its cosine correction is comparable to sensors with much larger apertures.