The answer depends mostly on the user's environment. When viewed indoors or in a dark cabinet, the fiber can be much longer than if it's trying to be viewed outdoors. Compared with 532 nm light, the common red wavelength 635 nm appears only 27% as bright. A 532 green laser appears 4 times as bright as a 635 red laser -- but the green visual interference distances are only 2 times the red. This VFL has a fiber stub; its total emission is -1. The Class 1 limit (+3 dBm/2 mW) is intrinsically safe in all circumstances and is the only. Monochromaticity: A red laser pointer emits light within a very narrow wavelength range, around 630–680 nanometers. Concentrating energy into a single color prevents losses across the spectrum. This coherence allows. Color (wavelength) — For bright-light interference with vision, a green laser will appear brighter to the human eye than a red or blue laser of equivalent power and divergence.