Shining light on lasers: Illumination technology enters a new phase


The recent introduction at CinemaCon 2014 of the first commercially available laser-illuminated projectors puts the cinema industry in the forefront of what can be considered its fourth generation in illumination technology. The type of Illumination—the light behind the picture—is fundamental to cinema, and changing it has implications that extend across much of the industry.

The very first cinema projectors—those being introduced before the turn of the 20th century—were illuminated using limelights. Limelights, whose name survives to this day, used bottled hydrogen and oxygen to produce a flame directed into a surface made of calcium oxide, causing it to glow with an intensely bright white light. In their day, limelights had a particular advantage: They did not use electricity. A hand-cranked limelight-illuminated projector could be set up and used anywhere. Burning hydrogen gas alongside nitrate film, however, presented serious safety concerns, motivating the industry to quickly adopt a better solution.

Carbon arc
Shortly after the turn of the century, carbon arc lamps were widely used and remained the primary source of cinema light for 70 years. The carbon arc lamps were safer and dependable, but they used lots of electricity and required frequent operator intervention. The carbon rods burned away and had to be replaced frequently. During the show, they required constant adjustment with feed motors and other mechanisms to maintain constant and uniform illumination. The carbon arc lamps could go bright enough for the largest auditoriums, but they had a practical limitation of around one hour maximum running time, which therefore required dual projectors and changeovers between reels.

In the 1950s, the third generation of illumination technology—the Xenon bulb—was introduced. Also a form of arc light but with the electrodes mounted within a glass jacket pressurized with rare gases, the Xenon bulb produced a stable white light—similar to sunlight—that could reliably shine for long hours without the need for adjustment. The introduction of the Xenon bulb with its extended running time allowed the use of single projector platter systems, which in turn enabled the exhibition industry to expand beginning in the 1970s with multiplex construction, all requiring less per-screen operator involvement. The introduction of the Xenon bulb was the beginning of the end of the projectionist.

Although the advantages of the Xenon bulbs far outweighed its disadvantages—i.e., higher cost, and special handling during replacement—it took the industry around 40 years to convert from carbon arcs to Xenon. Initially the first Xenon bulbs were not bright enough to address the large 70mm auditoriums, so many of those auditoriums continued for years with carbon arcs. In the developing cinema market overseas, Xenon illumination was slow to spread, largely because the local cinema industries were stalled by lack of investment and often the local power infrastructure didn’t have the stability to support Xenon operation. Markets that have recently expanded such as India or China remained largely carbon-illuminated well into the 1990s, with Xenon coming in only with the fairly recent wave of new construction.

Compared to carbon arcs, today’s generation of Xenon bulbs are high-tech devices and their higher cost has become painfully apparent to multiplex operators considering the increased number of auditoriums and their relatively short life. New Xenon bulbs begin dimming immediately and typically last around 1,000 hours before they reach 50% of their original brightness. The need to replace Xenon bulbs on scheduled intervals has caused the cost of illumination to be a major budget item for today’s exhibitors.

Until now, Xenon illumination has been incorporated in the designs of most digital-cinema projectors because there has been nothing readily available that offered the brightness and color consistency of a Xenon lamp. Although both NEC and Sony have introduced smaller projectors that use a bank of lower-cost High Pressure Mercury lamps, the Xenon is currently used in all mid- and high-brightness cinema projectors. From an image quality perspective, Xenon has allowed continuity in moving the rest of the industry from 35mm film to digital by providing defined light and color characteristic standards that had to be met. To this day, Xenon remains the most practical and cost-effective illumination technology for most mainstream projector applications.

A new light
The cinema technology industry is largely driven by a quest to increase the cinematic “wow” factor. This produces a constant competition between equipment vendors to introduce innovations that give filmmakers increased range for creative expression. When moving from 35mm to digital projection, a fundamental starting principle was to target image quality levels that would be comparable to the reference studio print. Then, as the new digital technologies matured, the aim was to provide the ability to improve the image even further.

At that time, a small number of engineers believed that the obvious place to start would be with an entirely new illumination system that would be the equivalent to Xenon in color balance, and ideally improve upon its color range, increase its light output and increase its lifetime, while also reducing its long-term operating costs. The illumination source that offered this was the laser, but there were major obstacles that had to be overcome.

The first challenge was that no laser companies were making components that could be readily adapted into cinema projectors. Entirely new laser solutions had to be engineered. Then there was the issue of picture quality. Lasers tend to naturally “sparkle,” and technologies had to be developed to eliminate any negative impact on the picture. Finally, there is cost. Lasers used in other applications tend to be expensive, and for the cinema market the total cost of the laser-illumination system had to be reduced to make the solution viable from a business perspective.

Further complicating their potential use in cinema, lasers are used in such diverse applications that there are numerous governmental and international safety regulations that need to be either met or waived when they don’t apply. In cinemas, the light generated by the laser light source creates pure Red, Green and Blue light that is spread across the imaging devices—the three DLP Cinema® chips. Then, the reflected light is further spread by the lens when focused on the screen, so the light projected into the auditorium remains safe. The light emitting from the projector is essentially the same as before, except for potentially being brighter and covering a greater color range. However, getting regulatory clearances to commercially deploy lasers inside cinema projectors was a major hurdle that has largely been achieved. For the current products, recent approvals have been granted on a product or manufacturer basis and all the projector manufacturers are working with the Laser Illuminated Projector Association (LIPA) to simplify regulatory compliance in the future.

For the cinema market, laser illumination has an immediate and relevant benefit: getting the 3D light levels up to a reasonable standard. There are two primary ways lasers help 3D: First, the laser beams are smaller but have more light output, so they allow for much higher lumen projectors in the same space. Estimates are that lasers can potentially double the lumen rating for a given size projector. Beyond that, the lasers themselves can help with the 3D process, eliminating some of the light losses caused by the 3D filters in use today. The net effect is that the light efficiency of the 3D projector can be dramatically increased using laser illumination.

For both 2D and 3D, a laser-illuminated projector is saving power over a conventional projector. Depending on the specific system design, a laser projector will consume somewhere between 50 to 70% of the power required by an equivalent Xenon projector. This saving will be a substantial benefit for exhibitors operating multiplexes in markets with expensive power.

Laser-illumination systems can be categorized into two different types: First there is the discrete Red-Green-Blue (RGB) laser group. In these, all three primary colors are created direct from the lasers. This approach is used to create very high light levels but is also more expensive to implement. The second category is known as Blue Pumped Phosphors (BPP), where a Blue laser is used to stimulate phosphors which glow with secondary emissions to produce the Red and Green. This is more economical, but has lower maximum brightness. Both the RGB and the BPP laser techniques are finding applications in the next-generation cinema projectors.

Lasers have a long lifetime, typically estimated to be 20K to 30K hours, and unlike Xenon bulbs, the lasers keep their original brightness much longer through their life cycle. Customers should be aware, however, that various laser manufacturers are rating laser life differently. Typically, the RGB laser’s life is based upon a 20% reduction in brightness, while BPP laser manufactures have historically been using a 50% reduction as the end-of-cycle point.

The development toward laser illumination applies not only to cinema projectors but to all projectors used in high-brightness applications, so the cinema industry will benefit from their increased production. The projectors used in cinemas—i.e., DCI-approved—have the additional challenges of meeting stricter color and security standards while also addressing the day-to-day operational requirements of modern cinemas.

The projectors
At CinemaCon 2014, we saw the first generation of laser-based cinema projectors, from the three DLP Cinema-licensed projector manufactures: Barco, Christie and NEC. Interestingly, each company has taken a different approach and is initially targeting a slightly different segment of the market. Both the NEC NC1100L and the larger Barco DP4K-60L are fully integrated designs, while the Christie laser projector is a dual-head configuration with image-integrating optics.

Both Christie and Barco are looking at the high-brightness end of the market with their new designs. Each is 4K and can play multiple 3D formats. Each is using the high-brightness RGB laser technology and estimating at least 30,000 hours of life. Barco, with the integrated DP4K-60L, is initially targeting the new premium cinemas that could use more light and possibly those that are upgrading a dual stack of Xenon projectors to simplify operations. Christie is also targeting the premium cinemas, the larger halls, and special venue facilities where running Xenon bulbs is just too costly or can’t acceptably project 3D due to low light levels. All the manufacturers are introducing their initial laser products where they see that their customers have immediate needs and are surely planning to extend their product lines to cover the broader market before the replacement cycle for the current generation of equipment begins.

Where the lasers are physically located is a point of differentiation. One exciting aspect of laser illumination is the possibility of having silent projection heads in the auditoriums and a remote light source conveniently located elsewhere. Remotely locating the light source has the advantage of making the projection system component’s modular and upgradable. Making a first step in this direction, Christie puts the lasers in an external cabinet that can be located up to 100 feet (30 meters) from the projection heads.

Christie also feels that using two projection heads leads to a more enjoyable and brighter 3D picture, since each eye image is being continuously projected. When using the Dolby 3D 6 primary system, which uses three separate primary colors for each eye, each projector head separately projects those colors for each eye image without interruption. Christie has incorporated setup software so the dual heads can be quickly aligned. Each projection head has a light output rated at 60K lumens, resulting in a cumulative 120K lumen light output.

The Barco DP4K-60L also incorporates a specially adapted version of the Dolby 3D 6 primary system in a single-head, integrated configuration. The RGB lasers electronically shift between two different sets of RGB colors, alternating between left and right eye images. Barco engineers believe in the practical advantages of an integrated design. As for 3D, they point out that the 3D 6 primary system has been used successfully since 2006, with the vast majority being single projectors, and the elimination of the color filter-wheel along with the increased light output, resulting in proven 3D that exceeds the needs of the vast majority of premium auditoriums.

NEC’s 2K NC1100L, the first laser-illuminated projectors to receive DCI compliance, uses the BPP laser technology and has estimated 20,000 hours laser life. These projectors are intended for small auditoriums with screens up to around 35 feet (14 meters), depending on the model and screen gain. NEC’s initial focus with the NC1100L is reducing the exhibitor’s total cost of ownership (TCO) over the existing Xenon designs in the same class of small and mid-sized projectors.

Sony, which had demonstrated various projectors incorporating laser illumination beginning in 2005, has not publically announced a laser-illuminated cinema projector. However, considering their expertise in the subject, a laser-based product is widely believed to be in development. In recent statements, David McIntosh, who leads Sony’s digital-cinema team for Europe and the Americas, has pointed out that for the vast majority of exhibitors, it is impossible to make a solid business case for laser in 2014 and that when introduced laser illumination should make meaningful improvements over the current bulb technologies. McIntosh hinted Sony would be showing a few customers an advance look at their laser development later this year. From this, we should expect Sony will have a laser product for cinemas in 2015 and that it will look quite good.

Aside from market timing and their initial product offerings, all projector manufacturers seem to agree that the next generation of cinema projectors will use laser illumination, but are not convinced about the practicality of retrofitting existing Xenon-illuminated projectors with laser modules. Potential issues are the high cost of integrating into all the various modules, verifying performance, providing product support, and even the possible need for DCI recertification.

At CineEurope in June, the Italian projector company Cinemeccanica introduced their CineCloud Lux Smart laser retrofit solution for DLP Cinema projectors. The initial information describes it as a RGB fiber system that scales up to 55K lumens, with a 50% power reduction, and an estimated 20,000-hour lifetime. The Cinemeccanica development could be the first of others to follow, if an aftermarket retrofit solution can be proven to perform as well as a Xenon bulb but at a lower TCO for the exhibitor. Potentially reducing laser costs further, there are laser component manufacturers that are just realizing their customer base is expanding into cinema and high-brightness projector markets and are likely willing to jump in with new solutions and better pricing as the volume increases.

The acceptance of laser illumination over Xenon will be largely driven by each exhibitor’s specific TCO analysis. Although laser illumination will most certainly lead to possibly dramatic improvements in the picture quality over time, these—like high dynamic range, greater contrast, and increased color space—will likely be rolled out in the coming years from multiple technology vendors. While being profound for the industry and the filmmakers, these changes as seen by the audience will likely be incremental, making it difficult for exhibitors to generate return though the box office. The exception is 3D, which is marketable today. Laser illumination will allows cinemas to show 3D titles at reasonable light levels, adding life and excitement to what has been a rather dim picture.