Without question, the marketing of laser-illuminated cinema projectors greatly exceeds the degree of education received by exhibitors about this new technology. In my role as co-chair of the ASC (American Society of Cinematographers) Subcommittee on Laser Projection, much information has been learned that should be helpful to exhibitors.
It’s useful to understand the core technology. Most if not all laser-illuminated projectors utilize a class of semiconductor technologies called Vertical Cavity Surface Emitting Lasers. VCSEL technology produces better yields and higher densities per wafer than any prior semiconductor laser technology, reducing cost. There are numerous methods that can be applied to VCSEL fabrication, creating a rich market for niche products from specialist suppliers. This suits a diverse marketplace where iPad quantities are unheard of.
VCSEL devices are fabricated to laser at specific frequencies of light. The frequencies required of digital cinema P3 primaries require specialized, low volume production. This can result in a non-competitive market where there is a sole supplier: Barco, Christie, and IMAX, for example, obtain their lasers from Necsel, owned by Ushio, a major supplier of xenon lamps (and also the owner of Christie). Specialized production and low volume should be kept in mind when considering the potential for cost reduction.
Image quality of is often taken for granted, but the truth is that the image quality of laser projectors has yet to be vetted by the filmmaker community. This is not a trivial point. When the transition from film to digital projection was first considered, the MPAA, in a statement from (then) CTO Brad Hunt, dictated: “The picture and sound quality of digital cinema should represent as accurately as possible the creative intent of the filmmaker. To that end, its quality must exceed the quality of a projected 35mm “answer print” shown under optimum studio screening theater conditions.” The MPAA’s statement was considered a milestone, and applauded widely by the creative community. Although “answer prints” are now nearly a thing of the past, the sentiment for quality expressed then still resonates within the filmmaker community. Today, that sentiment is applied towards xenon-illuminated imagery in the P3 color space. In spite of this sentiment, the manufacturing community has largely overlooked the filmmaker community, focusing only on the sale of new technology to exhibition.
This is not how digital cinema began. TI spent years working with studios and creatives to get its DLP Cinema technology to acceptably color an image. While DCI is the name often associated with the P3 color space, it was TI that pioneered it. TI preserved the quality of its finely-tuned light path by licensing the technology (this is what defined “DLP Cinema”). However, TI has taken a back seat in the development of laser-illuminated projectors, and the projector companies themselves are not undertaking with laser projection the important steps first taken by TI when developing DLP Cinema.
A possible rationale for bypassing filmmaker approval is that laser-illuminated projectors, with the exception of those from IMAX, utilize the original TI light path and merely substitute a laser-illuminator as the lamp. However, this is not a simple substitution. The frequency spectrum of laser primaries, quite narrow due to the nature of lasers, do not present uniform colors to all eyeballs due to an artifact called metameric failure. Another quality-related issue exists called “speckle.” Speckle is seen as moving spots of brightness on the screen (thus the term). As with metameric failure, this problem is also worsened when spectrum primaries are narrow. Quality imagery projected by laser illumination is a nascent practice, and there is no agreed method for measuring speckle. Thus, the measurement you may find from one manufacturer will be meaningless when attempting to compare it with that of another. Speckle is easiest to observe in smooth color patches.
As one might sense, a common method could emerge for mitigating the effects of both metameric failure and speckle: wider spectral bandwidths for each primary. The spectral bandwidth of a laser can be as narrow as a single nanometer of wavelength. It could be that 40 nm (a guess) will be enough to satisfy the creative community. But no one has tried this, and trying is easier said than done. While multiple lasers are necessary to achieve high light levels, it requires a manufacturing and selection process which does not exist today. Going back to how VCSEL lasers are fabricated, any deviations in frequency will lead to more specialized production and a higher price tag.
3D can be complicated with laser-illumination, with part of the problem self-imposed through lack of agreement among manufacturers. Manufacturers like to tout high 3D efficiency numbers, by sending one set of three primary frequencies to one eye, and a different set of three primary frequencies to the other eye. (The so-called “six primary” projectors.) When glasses are constructed to allow only one trio of frequencies to each eye, an impressive degree of stereo separation will occur. 3D achieved in this manner uses the spectral filter technique patented by Infitec and licensed by Dolby. However, Barco and Christie, the two companies marketing six primary projectors, chose a different set of primaries for each eye. If one thought Dolby 3D glasses were expensive, the fragmentation in production caused by these diverse paths will only make six primary laser projection 3D glasses more expensive. If one wants to bypass the use of costly glasses and simply use a polarization-preserving screen for polarized 3D (for which, in the US, glasses are free), then a different problem occurs. Some companies polarize laser light as a technique to mitigate speckle. Use of a polarization-preserving screen removes the mitigation, and speckle can be seen. Not everyone uses polarization as a speckle-mitigation technique. Christie prefers to vibrate the screen, rather than attempt electronic methods. Christie’s method will work well with polarized 3D, but, ironically, Christie disses polarized 3D.
Economics is probably the issue most widely understood about laser-illumination. Current pricing falls in the US$8-$10 per lumen range, making these projectors extremely expensive. Projector companies hope to see the per-lumen figure fall by 50%-60%. But quality issues, once properly understood, could drive prices in the other direction, as just described, offsetting any cost efficiencies achieved.
Overall, one has to justify expense with benefits. Aside from higher light level, however, benefits are hard to find. Laser projection was originally touted as an energy-saving projection technology, but that claim is no longer made. While color issues need further examination, there remains the fact that those projectors using the TI DLP Cinema light path will suffer the same limitations in contrast as their xenon-illuminated brethren. Anyone that may think that such projectors can one day be adapted to high dynamic range projection should reconsider that thought. HDR generally requires a larger color space, which will be difficult, or at least inefficient, with the TI DLP Cinema light path. A greater shortcoming, however, is that HDR, by definition, requires high contrast, else one ends up with higher black levels and a washed-out image. TI DLP Cinema is limited to around a 2000:1 contrast ratio, which is insufficient for HDR. It follows that HDR laser projectors will require a different light path than that of DLP Cinema.
Laser-illuminated projection is an exciting and promising area, where much exploration and development remains to take place. Those who wish to be on the leading edge of cinema projection will undoubtedly claim bragging rights by installing a laser projector today. And where would we be without such early adopters? But those on the fence might look back to the early days of digital cinema, when 1.2K projectors were first installed, to appreciate the current state of laser projection.