Industrial photoelectric sensors transmit fixed wavelengths of light to determine the distance, absence, or presence of an object by ignoring ambient light and detecting changes in the transmitted light returning to its receiver. The sensors are housed in rugged cases ideal for industrial environments. Sensing methods include cross-beam, through-beam, diffused, reflective, retroreflective, transmissive, proximity, distance and line focus. The sensors are further differentiated by light source color and wavelength, sensing distance, ingress protection and output configuration.