Prototype projector still shines through in sun-lit rooms

Scientists in Germany have developed a tiny projector that displays or records sharp, bright images and video, even in a sun-lit room.

The prototype device uses an array of microscopic lenses to provide an improvement in image quality comparable to ‘the advance in television from the cathode ray tube to HDTV’, according to its inventors at the Fraunhofer Society in Germany.

The 3mm-thick technology, which will go on display at Tokyo’s Nano Tech 2011 trade show next month, could be integrated into devices such as smartphones and laptops, but could also be used to project large digital advertising displays.

It uses an array of 250 micro lenses, each with a tiny part of an image contained underneath in the device’s micro-optic system. When the micro images are projected using a powerful LED light, they combine as a high-quality composite image.

One of the device’s main advantages is that when creating larger or brighter images you don’t need to increase the size of all the technology, physicist Marcel Sieler of the Fraunhofer Institute for Applied Optics and Precision Engineering told The Engineer.

‘Laser scanning approaches are not scalable for higher brightnesses without increasing all of the system dimensions and it’s the same for LED pico projectors,’ he said. ‘In our case you would just increase the area size of the projector but it would always be super-slim.’

The technology was inspired by a device known as a fly’s eye condenser used to smooth out beams of light from LEDs. The Fraunhofer team had to design a very precisely arranged array of aspheric lenses designed with a specific shape.

The array is created from a glass wafer with moulded micro-optics on either side. ‘You put a liquid monomer layer on top of the glass and press a negative tool into it and it’s polymerised to get the perfect shape for the microlenses,’ said Sieler.

As well as the basic proof-of-concept model, the team have also used the technology to create prototypes of a larger projector for advertising and illumination, a video graphics array (VGA) camera, and a video projector that takes images from a micro-LCD display.

The team is now seeking industrial partners to help commercialise the devices and Sieler estimates that it is likely to be five years before they are available to buy.

Dr Chris Harris of Light Blue Optics explains how the Cambridge University spin-out is aiming to make waves in the pico-projection business. Click here to read more.