Scanned laser projectors have been around as demonstration units almost since the laser was invented. Four recent unrelated announcements indicate that scanned laser projectors may finally become a significant product in the marketplace.

Matt Brennesholtz
Insight Media Analyst

Microvision announced on October 22 they had signed a distribution agreement with Mint Wireless Limited in Australia for their picoprojector and Mint Wireless, in turn, has accepted a purchase order for the OEM version of the projector from Uniden. What is finally making this product commercially viable is the availability of high-speed, frequency-doubled green lasers at a relatively affordable price from suppliers such as Corning and Osram.

Talking about green lasers, Sumitomo has discussed progress in its research lab on direct emission green lasers, including an announcement of a direct-emission, GaN-based 520nm, 2.5mW laser that could run CW. Earlier, they had announced a 531nm laser, but it could only run in pulsed mode. While 520nm is not ideal for displays, it isn’t bad and would make an acceptable green primary for most applications. 2.5mW isn’t enough for a picoprojector like Microvision’s but it is getting there. We looked at a technical paper from their R&D group, not a product announcement, but it shows progress in the right direction.

Perhaps the most interesting recent announcement was from Brother Industries, Ltd on October 20th on a scanned laser retinal display. This system is similar to the Microvision approach except no projection screen is involved. The scanned laser is aimed directly into the viewer’s eye and the image is written directly on the retina. For this design, far lower laser powers are needed and the 2.5mW from the Sumitomo laser would be perfectly acceptable. Brother does not say whose laser they are using, but they do say they are using a direct emission green laser, not a frequency doubled one. They say this is the first ever display product based on a direct emission green laser. The system consists of three modules: a light source module, an optical scanning module and an eyepiece module. The light source module is combined with the power supply into a 350g package that can be worn on the belt. The scanning and eyepiece modules are combined in a 35g package that can be worn as glasses on the head. The two packages are connected by a fiber optic and electrical cable carrying the laser light plus the power and control signals for the scanner. We saw prototypes of this system about two years ago and the size reduction has been impressive.

The scanner system is an in-house development at Brother and an outgrowth of their printing technology. According to their announcement, "Brother has been developing piezoelectric MEMS technologies based on its inkjet printing technology. With this technology, it successfully developed in-house an optical MEMS scanner (high-speed scanning mirror device), with world-class operating frequency, to create clear images." Like the Sumitomo green laser, this unit is a demonstration unit but Brother says they plan to commercialize it in fiscal year 2010.

The final announcement came from Maxim who announced the MAX3600 laser driver IC. This IC combines red, green and blue laser drivers onto a single chip. The chip actually includes a 4th driver intended to drive a noise diode run in parallel to the green laser, said to be required when you use a "synthetic green laser." (Whatever that means.) According to Maxim, this reduces the board area required by the drivers by 75% and the power consumed by 30%. The 2 ns switching time of the driver enables either 1080p or WXGA resolution. No indication from either Maxim or Microvision that this is the driver chip in the PicoP but it certainly wouldn’t surprise me if it were.