Engineers across the globe are making advances into simplifying the lasers used in mini-projectors – specifically the ones providing the green output – in an effort to make pico-projectors even more accessible.
The aim is to find a permanent direct green source to replace the frequency-doubled version that is currently used in small projectors.
The advantages of finding this simpler source will make the models cheaper to make, far more compact, less prone to speckling, capable of higher modulation rates and allow projection of high-definition images.
The most promising contender is a green variant of the violet laser diode emitter, now widespread in Blu-ray players, which is being developed by German technicians, Osram Opto Semiconductors. In early 2010 they reached the milestone of creating a laser to deliver the minimum output of 50 mW that is required for a direct source to work, and have built on it since.
Japanese firm, Nichia, have managed one step futher, however, and have already been able to begin commercial shipments of a 50mW laser that they say is competitively priced.
The companies are now working on how to bring down the high amounts of energy needed to power these lasers, which would very swiftly drain the battery of a mobile phone. A joint project between Sony, Hitachi and Japan’s National Institute of Advanced Industrial Science and Technology (AIST) is advancing on this, having just reported a low-threshold-current laser that emits 1.5 mW at 545 nm.