Laser-Illuminated Projectors at NAB 2015

Two RGB laser-illuminated projectors were demonstrated at NAB this year, and they looked quite amazing.

Even though NAB is a convention aimed primarily at broadcasters, its scope has expanded to include other elements of professional media. At this year’s show, I saw a couple of RGB laser-illuminated projectors, which I believe represent the future of digital-cinema and, eventually, home-theater projection.

Over the weekend before the exhibit floor opened, the Technology Summit on Cinema included a session on laser-illuminated projectors (LIPs). The new technology offers several advantages over xenon lamp-based projectors, including the potential for dramatically improved image quality, lower power consumption and cost of operation, and reduced environmental impact. However, some challenges remain, such as reducing the purchase price and regulatory reform—in the US, LIPs are legally treated like raw laser beams in terms of safety regulations (even though they are not nearly as dangerous as laser beams), while in Europe, laser devices designed to act as lamps are regulated like lamps.

There are currently over two dozen screens worldwide with LIPs from Christie, Barco, Imax (based on Barco), and Dolby (based on Christie). I recently saw the Imax LIP system in action, which you can read about here.

The session included a representative from Barco, which had installed one of its DP4K-60L 4K LIPs in the room as seen in the photo above. He pointed out that Barco’s approach is a modular design with dimmable lasers inside the projector housing and active, outboard liquid-cooling units called “chillers.” Putting the lasers inside the projector provides higher efficiency than outboard laser modules connected via fiber-optic cables, he claimed, which means fewer lasers, lower heat, and lower cost.

A single projector can achieve 20,000 to 56,000 lumens of light output, depending on the number of laser modules installed in the projector, with higher MTBF (mean time between failure) than a dual-projection system, and there are no alignment issues. Also, a single projector can display 6P (6-primary, aka color-separation) 3D with dichroic-filter glasses, much like Dolby 3D. As for despeckling, Barco uses several techniques, including wavelength spreading, multiple light direction and polarization, and special optics; screen vibrators can also be used.

According to the Barco rep, the projector exhibits a contrast ratio of 2500:1, which is not true high dynamic range, but it’s better than what a lamp-based 4K projector can do. It can reproduce the BT.2020 color gamut in 2D or polarized 3D mode, but 6P-based 3D is limited to DCI-P3. The laser light engine is spec’d to lose 20% of its brightness over 30,000 hours, depending on the level of cooling—lowering the temperature by 10° C doubles the lifetime of the lasers. In that same 30,000 hours, a xenon lamp would have to be replaced 60 times at a couple of thousand dollars each.

We saw a few 3D clips on a RealD Ultimate Screen prototype (24′ wide, 2.1:1, 91% reflectivity, 1.4 gain, 57° half-gain angle), which I wrote about in my coverage of last year’s NAB show. In this case, the projector used RealD XL circular polarization, not 6P. The clips were all 1.85:1 and graded for 14 foot-lamberts to reach each eye through the glasses. The tiger-swimming scene from Life of Pi, the opening hunt scene from Dawn of the Planet of the Apes, and the opening musical number from Rio 2 all looked gorgeous with plenty of brightness, vibrant colors, and deep blacks.

On the show floor, Christie was showing the CP42LH, which is the platform for the Dolby Vision projector that will be installed in some AMC Prime theaters this year. It has 4K resolution and an outboard, modular laser light engine; each module includes red, green, and blue lasers, and the modules are coupled to the projection head by fiber-optic cables. Up to 12 modules can be installed in a rack, allowing the projector to produce up to 60,000 lumens. Like the Barco projector, the peak brightness drops by only 20% after 30,000 hours.

The Christie CP42LH laser-illuminated projector can achieve a peak brightness up to 60,000 lumens and a color gamut out to BT.2020.

Another hallmark of the CP42LH is its ability to reproduce the BT.2020 color gamut. Of course, lasers make this relatively simple, since the BT.2020 primaries are single-wavelength red, green, and blue. When I asked a Christie rep about the problem of metameric failure with BT.2020, he said the difference in color that different people perceive is not all that great, so it’s not such a big deal as some make it out to be.

A demo was presented in the Christie booth with no light control—there was plenty of ambient light from the show floor. The projector fired onto a 20-foot-wide Da-Lite HD Progressive screen; I was told it was unity gain, but in subsequent research, I learned that the HD Progressive material is available with 0.9 or 1.1 gain, and I don’t know which was used by Christie.

Most of the demo content was mastered and displayed in the DCI-P3 gamut, but there was also a comparison of BT.2020, P3, and BT.709. Several shots were paused while the color gamut changed from one to the next, and the difference was striking, especially in the red hues, which looked positively orange in 709. The demo ended with a clip from Rio 2 that had been remastered in BT.2020. It looked deeply saturated, though we were told it was not necessarily the creative intent. And of course, all the ambient light in the environment made it impossible to judge the real quality of the image.

Many AVS Forum members are chomping at the bit for laser-illuminated projectors, but they are not yet available for home use—at least, not with RGB lasers. (The Epson LS10000 and LS9600e are blue-laser/yellow-phosphor-wheel hybrids, and the SIM2 RGB LIP demonstrated at CES 2015 was an early prototype.) The best we can hope for in the immediate future are commercial cinemas with laser-illuminated projection. Even those are pretty scarce at the moment, but I expect there to be more in the coming months and years. I’ll work on developing and maintaining a list of these locations here on AVS Forum, and I encourage you to seek them out to see for yourself what a wonderful image they can produce.