OD 5 and OD 7 are commonly encountered Optical Density ratings on laser safety glasses. Although OD 7 represents greater attenuation than OD 5, the highest number is not automatically the correct choice for every application.

Optical Density is logarithmic, meaning each increase of one OD represents a tenfold increase in attenuation. Consequently, OD 7 provides substantially more attenuation than OD 5 at the specified wavelength.

However, the OD rating must always be considered alongside the wavelength. A pair of glasses providing OD 7 at one wavelength may provide a lower OD at another wavelength.

Users should therefore examine the complete protection table rather than selecting eyewear solely according to its maximum OD rating.

Understanding both OD and wavelength coverage is essential when evaluating laser safety glasses for professional use.