Tilt compensated laser projection unit integrated into a mobile phone

Fraunhofer IPMS shows a miniaturized monochrome laser projector which optical part fits into a mobile phone. The system is based on its own two dimensional micro scanning mirror. The system contains an ultra compact projection head and a separate laser and signal processing unit. It allows the projection of arbitrary images and video sequences with a geometrical resolution of 640 x 480 pixels, 256 brightness levels per pixel and elementary color, and 50 hertz frame rate. The projection modules developed by Fraunhofer IPMS overcome limitations of conventional projection systems – like rather large components for light deflection and high power light sources that consume lots of electrical power and radiate most of it thermally – by deploying the micro scanning mirror as key element for image generation and lasers as light sources. The patented micro scanning mirror of Fraunhofer IPMS is an ideal base for the development of compact projection heads. It distinguishes itself by high mechanical robustness and ease of both electrical control and optical coupling of the laser beam. Independent from the projector technology one major difficulty has to be solved: Movement of a handheld device will affect the image quality. Every object has 6 degrees of freedom, 3 translatory and 3 rotatory. Position changes are comparably slow and the human eye is used to follow moving objects and images. More difficult is the compensation of rotatory movement that occurs from shiver with a frequency to smear image pixels to lines. This has to be compensated electronically, which is shown in the demonstrator by adding an Inertial Measurement Unit to the system and electronically compensating rotatory movements. Additionally the movement can be used actively to control software functions of the handheld device.