Lasers operating around 635nm and 650nm are commonly used for alignment, positioning, measurement, research, and industrial applications. Although these wavelengths are visible as red light, sufficiently powerful sources can present a serious eye hazard.

The exact wavelength should be confirmed before selecting protective eyewear. Laser safety glasses are designed around specific wavelength ranges, and protection can vary significantly across the spectrum.

Optical density is also important. An OD rating describes the attenuation provided by a filter at specified wavelengths. The appropriate rating depends on the laser's output and operating conditions.

The visible appearance of a filter should not be used to determine whether it is suitable. A dark lens does not automatically provide the required OD at 635nm or 650nm.

Visible Light Transmission (VLT) can also be useful when comparing filters. Higher transmission may provide better visibility for certain tasks, while darker filters may provide different optical characteristics.

Some laser safety glasses cover multiple red and infrared wavelengths, making them useful in environments where several sources are present.

Before using eyewear with a 635nm or 650nm laser, compare the laser specifications with the complete wavelength and OD ratings of the filter. Proper selection is more important than lens color or appearance.