Laser projection is here to stay. The technology chosen by Darth Vader as his illumination/weapon source is the preferred choice for today´s projector manufacturers. But why laser? What are the benefits? And where does it fit in the history of projection?
I have spent 10 years working for a projector manufacturer (Barco/projectiondesign). During this period, I witnessed the rapid development of light sources, and am proud to have been part of the introduction of the first laser-only projector by Barco, at Cinema Con 2014.
In this article, I will cover the following topics:
- The history of projection
- The history of projection illumination sources
- Different types of illumination sources
- What are the benefits of laser projectors?
- What is the financial impact of laser projectors?
- Which technology do I choose?
- … and my short history from working at a projector manufacturer for 10 years
Let’s start with my history from projectiondesign and Barco
In 2005, I joined the Norwegian projector manufacturer, projectiondesign. At that time, projectiondesign had recently introduced the first DLP based two-lamp projector (F3) which took light levels to about 7 500 lumens. In 2009, projectiondesign introduced the first solid-state illumination projector using LED (FL32), bringing the light levels down to 500 lumens. But for good reason. The LED-illuminated projector was a neat fit for a niche market where two of the key advantages over lamps were important:
- Long lifetime of the illumination source (100 000 hours)
- 360-degree projection installation (all axes)
In 2012, Barco acquired projectiondesign, and we became part of a bigger family of projectors. Developments continued and both laser phosphor projectors and pure laser projectors were works in progress. While Barco had demonstrated their forthcoming laser projector in 2011 and 2012, it took until 2014 for the first true laser projector to be released commercially. At CinemaCon, we showed a 60 000-lumen 4K projector, capable of playing 4K content at 60 fps and 3D content in full 4K resolution.
It was a true game changer for the cinema market and projection in general. At end of 2017, Barco has installed more than 5 000 native laser projectors in cinemas around the world.
History of projection
The history of projection reaches all the way back to camera obscura and magic lanterns, but it was the development of optics in the late 16th and early 17th century (when both the telescope and microscope were invented), that made a major impact on projection as we know it today.
Written information about the camera obscura principle (often referred to as pinhole image) has been found in Chinese writings (Mozi) dating back to the 4th century BC, and the magic lantern can be seen as a development of camera obscura. The Dutch scientist Christiaan Huygens is generally recognised as the true inventor of the magic lantern which is an early type of more traditional image projector, and used pictures painted or printed on glass. This projection technology was superseded by a much more compact version – the 35 mm slide projector.
The first movie projector was the Zoopraxiscope, by the pioneering British photographer Eadweard Muybridge in 1879. To create motion, the Zoopraxiscope rapidly projected images from rotating glass disks.
But it was The Lumière brothers who invented the first really successful movie projector based on the work of the French inventor Léon Bouly: the Cinematograph, a film camera, projector and printer in one. Their first film Sortie de l'usine Lumière de Lyon, was shot in 1894, and publicly screened in 1895. At the Paris Expo, films by the Lumière Brothers were projected onto a large screen measuring 16 by 21 meters.
Movie projectors continued to evolve all the way into late 2000, where they were gradually replaced by digital cinema projectors. Digital projectors offer a number of advantages over traditional film, and the digitalization of modern cinema was inevitable. With no moving parts except fans (and imaging devices), digital projectors are relatively compact, have no film rolls that will tear or show scratches (thus no need to change the reel mid-screening) and content distribution is far simpler. Initially the films were shipped physically, but digital all-electronic distribution has eliminated all physical media shipments.
Since the 1950s, generations have been exposed to endless and tiresome slideshows, of mind-numbing vacation photos, or in history and art lessons at schools. During one such epos, I managed to fall asleep, tipped my chair and gashed my cheek – marked for life by sheer boredom!
However, far from all the uses for slide projectors were uninspired; the creative use of slide projectors (many of them, simultaneously) was one of the reasons Dataton entered the world of multi-display, introducing PAX, a four-projector slide control unit. That, however, is another story to be told later.
The overhead projector is built on the same principle as the 35 mm slide projector, but differs in that the transparencies (slides) used are much bigger, often up to A4 or US letter size. Overhead projectors also found their way into schools and corporations in the late 1950s. This technology remained popular until the late 1990s, when other methods of projection started to make an impact. A LCD (Liquid Crystal Display) variation of this technology came to life in the early 1980s, letting content be played from computers and video players (VCRs). At first, it was limited to monochrome, but by the end of the decade they could show colors, too.
Both video players and overhead projectors bring vivid memories of frustrated teachers to life. How hard it seemed to be, to make sure the video actually played and to make sure the overhead transparent was oriented properly.
These old, gigantic ships of projection made their way to market in the 1950s too – a lot happened then in the history of projection. These projectors used cathode ray tube (CRT) to generate the image, with the first color CRT projectors available in the early 1950s. To create color, they had three separate CRTs and their own lens. How fun it was, to align a CRT projector… With the introduction of digital video projectors (LCD, and DLP – Digital Light Processing), the CRT projectors died late 1990s and early 2000.
However, due to the fact that this kind of projector has very specific, high-quality performance attributes (deep black levels, no motion blur and long service life) as required in several niche applications, they have remained in use much longer. In fact, you can still find simulators using them today.
The era of digital projection began in the late 1990s and early 2000s, when technologies, such as Digital Light Processing (DLP), liquid crystal on silicon (LCOS) and LCD (liquid-crystal display) became available at acceptable prices. These projectors were smaller, affordable and digital. All characteristics that are highly appreciated by anyone interested in projection. Today you can find everything from tiny pico projectors the size of a matchbook with a handful of lumens, up to the largest, high-resolution beast boasting up to 60 000 lumens.
As I write this, the projector manufacturer Digital Projection has announced the world´s first 8K digital projector: the INSIGHT DUAL LASER 8K, with a resolution of 7680 X 4320 pixels and a brightness of 25 000 lumens. That’s 33 million pixels.
Differences in imaging technologies (such as DLP, LCoS and LCD) will be covered in a later blog post.
History of projection illumination
Now to what this blog post is really about. The history of illumination sources and why laser has become the #1 choice for high brightness projection. The following illumination sources will be covered in the article:
- Arc lamps
- Metal halide lamps
- UHP (Ultra-high-performance lamps/Ultra-high-pressure lamps)
- LED (Light Emitting Diode)
- Hybrid illumination
The concept of carbon-arc lamps was first demonstrated in the early 19th century. Arc lamp technology was one of the first commercial uses for electricity. An arc lamp produces light by an electric arc (also called a voltaic arc), and an arc is the discharge that occurs when a gas is ionized. The term is also used for gas discharge lamps, which produce light by an arc between metal electrodes through an inert gas in a glass bulb. The fluorescent lamp is an example of a low-pressure mercury arc lamp.
While carbon arc lamps were used in projection systems, it is the xenon arc lamp (a gas discharge lamp, that produces light by passing electricity through ionized xenon gas at high pressure) that is most known today. The xenon lamps are widely used in cinema projectors and other high-brightness projectors. While currently being replaced by laser projectors, xenon is still by far the dominant illumination technology in the cinema projector install base.
The benefits of xenon lamps are a short start-up time, wide and evenly distributed color spectrum which tracks well to natural sunlight, and it is the brightest lamp technology available. On the downside, xenon has a short life span and it is expensive.
Metal Halide lamps
The metal halide lamp is a technology developed in the 1960s. It is an electrical lamp that produces light by an electric arc through a gaseous mixture of vaporized mercury and metal halides. The lamps are referred to as mercury vapor lamps and were widely used in projection systems before being replaced by Ultra High Performance/Ultra High Pressure lamps.
Ultra-high-performance lamps/Ultra-high-pressure lamps
The ultra-high-performance lamp is a high-pressure mercury arc lamp most commonly known as ultra-high-pressure lamp (UHP is a Philips trademark). Unlike other lamps used in projection systems, it is not a metal halide lamp, but uses only mercury.
For projection, the performance of these lamps is well known and yields predictable operation. They can be used as stand-alone lamp configurations or in projectors with up to six lamps – to increase brightness. The lamps run up to 4-5000 hours, but most typically have a 2000-hour life span. The lamp requires a certain warm-up time and while the xenon lamps have a great and distributed color spectrum, UHP lamps have pretty poor distribution of energy in their color spectrum. It is wide, but unevenly distributed.
Light-emitting diode (LED)
The light-emitting diode (LED) is a two-lead semiconductor light source. When voltage is applied to the leads, energy is released in the form of photons, an effect called electroluminescence. Compared to other light sources, LED has a number of advantages, including long lifetime, small size, fast switching and low energy consumption. The major negative effect with LED compared to other light sources is that it traditionally had very low brightness output.
The first LED projector in the market was the FL32 from projectiondesign. It had about 400 lumens, but with recent developments in LED technology, projector manufacturer Norxe have brought to market a LED illuminated projector with more than 4 000 lumens, using the high-lumen-density ColorSpark HLD LED technology from Philips.
LED projectors are typically designed for niche applications
With the initial low-level lumen output, the LED projectors were typically used in niche applications, such as simulation, where the longevity and heavily reduced need for maintenance (the projector could run up to 32 000 hours before maintenance, with a light source capable of running 100 000 hours – or 11.8 years in 24/7 operation) were more important than the limited brightness output.
When used in DLP systems, the driving of the LEDs enabled the projector manufacturers to remove the color wheels, eliminating a weakness in the DLP one-chip projectors.
Some challenges were also introduced with the use of LED as an illumination source, such as its narrow bandwidth and optical design in systems using optical blends, where color refraction created unwanted artifacts. Design changes in the optical blends removed this limitation.
Hybrid light sources
Later, LED made its way into projectors as one of two light sources in a hybrid illumination system. The first projector to market with a combined illumination source using LED and laser phosphor, was Casio's XJ-A130 in 2010 (and other models based on the same platform). The unique quality of this projector was the combination of technologies to create the colors: red was made from a native LED, blue by a native blue laser and green was created by converting the blue laser through phosphor. It was announced with 2500 lumens and 20 000 hours illumination life span.
Laser phosphor illumination
One of the most common and affordable illumination technologies today is laser phosphor, and most projector manufacturers have released laser phosphor projectors. They are typically designed with a cluster of blue lasers, where red and green is created from yellow phosphor, or with red and blue laser, and yellow or green phosphor. This varies among manufacturers.
The first projectors released with laser phosphor as the illumination source were typically around 6-7000 lumens, but this has been pushed to 32 000 lumens in the Barco UDX.
Key benefits of the laser phosphor projectors are the life span of illumination source, typically at 20 000 hours and the possibility of 360-degree installation (all axes).
What are the benefits of laser projectors?
First of all, laser projection (both pure laser and laser phosphor) has a number of benefits. Let’s take a look at the most impactful ones here:
- Less maintenance. With laser/laser phosphor projectors, you dramatically reduce the need to spend (money and time) to keep the system running. Lasers with a life span of 20-30 000 hours reduces the need for maintenance.
- Lower downtime. With the need for less maintenance, the projectors will no longer be the guilty party for system downtime
- Installation flexibility. With the removal of lamps, the (majority of) projectors can be mounted in any orientation the installation requires. This will reduce the need for costly modifications of installation or complex mirror systems.
- Color performance. The laser phosphor does not have a great color performance, but true laser projectors do. With the coming requirements for REC2020 color space, laser projection seems to be the only feasible solution.
- 3D projection. With pure native laser projection, you can separate left/right eye with a higher degree of precision than ever before – and bright, vivid 3D content can come to life.
- Environmental friendly. A laser/laser phosphor solution uses up to 52% less power per lumen on the screen compared to xenon. That is even including power consumption for cooling.
Environmental friendly technology
In addition to the above-mentioned power efficiency, there are other advantages with laser/laser phosphor. With lower power consumption, you dissipate less heat and reduce the need for ventilation and cooling. And not to mention the fact that xenon lamps also are built with hazardous components.
For further reading related to the environmental impact of laser/laser phosphor , I recommend the following links:
- Lasers in cinema: a new shade of green, written by senior product manager Tom Bert of Barco
- The benefits of laser phosphor projection for cinema, written by Goran Stojmenovik, senior product manager of Barco.
What is the financial impact of laser projectors
Reduced operational cost is the major benefit of laser projection (or any solid state light source for that matter such as LED), as there is no need to swap lamps every 700-1000 hours in cinemas, or 1500-2000 hours in other applications.
Naturally, this will have a major impact on the operational expenses of running a projection system, as all projection investment will be moved to capital expenditure - the money a business spends to buy or invest in new goods.
For a lot of companies this is good, but there are other companies and organizations that for various reasons want to keep higher operational expenses. Perhaps this will drive new business models into the projection market, such as leasing and long-term equipment rental?
Which technology do I choose?
At the moment, the choice is between laser, laser phosphor and LED in my book. I do not really see any application where a lamp-based projector would have more benefits than any of the above-mentioned illumination technologies.
And how to choose among them? It all depends on the application, where you aim to use the projector .
Good luck in choosing!
(Blog Title shamelessly inspired by stolen from the article “Why Darth Vader never chose a lamp saber” written by Johan Bekaert/Barco in 2015.)