Green laser diode modules suited for medical applications

Green DPSS (Diode-Pumped Solid State) laser modules are generally large, expensive and noisy with low thermal stability. Green light is produced by the cumbersome method of doubling the frequency of an infrared laser. Direct emission green laser diode modules, however, are small, robust and offer impressive power stability over a wide operating temperature up to 50 degrees C. Their high beam quality and low power consumption open up new possibilities as light sources.

Tony Pope, M.D., the Optoelectronics Company, explained, “By using a low power, direct emission green laser, it is possible to achieve the same or better visibility as a high power red laser diode. This is because the human eye is most sensitive to green light which appears brighter than red light of the same output power. This is obviously beneficial when laser safety classifications must be taken into consideration.”

Because green light is more visible than red laser light of the same power output and laser safety class, the green lasers are particularly suitable for outdoor applications. Rangefinders and distance meters, such as those used by builders and surveyors, can be used over longer distances without losing beam quality and coherence.

With excellent beam quality, the new range of green laser modules are also suited for optical imaging and their small package size is advantageous for very compact designs. The new technology makes high colour rendering and contrast very achievable and enables fine details to be displayed, even over large distances, which is of interest to manufacturers of show lasers. Other applications include machine vision, biotechnology and spectroscopy.

The green laser diode modules produce a high-quality elliptical beam at 520nm and offer high output stability with optical output powers of up to 35 mW. With an operating voltage of 9V DC and a broad ambient operating temperature range from -10 degrees C to +50 degrees C, they are energy-efficient, requiring typically 140mA operating current at 35mW and offer a long lifetime at continuous operation.

Robust and reliable with externally adjustable optics and self-contained drive electronics, the modules are static, surge and reverse-polarity protected and RoHS compliant.  Mechanical dimensions are 53mm long and 12mm diameter and the housing material is anodised aluminium. Electrical connections are made via 300 mm external flying leads.