Using 660 nm visible red light laser in which beam spot can be reduced to 0.2 mm dia by utilizing adjustable iris, Model M18 can detect objects as small as 0.1 mm dia at distance of 150 mm. Operating distance can be extended by geared multiturn potentiometer to 600 mm to detect targets 0.6 mm in dia. It has operating frequency of 5,000 Hz, operating supply voltage of 10–30 Vdc, switched current rating of 200 mA, and stable sensing range from -25 to 55°C.