New Laser Illuminated Lighting Instruments (LILIs) are revolutionizing intelligent lighting by giving fresh artistic choices and improved operating parameters.
Laser illuminated lighting offers numerous advantages, including brighter, laser-like beam effects, smaller beam and spot diameters, and an increased color gamut. LILI light engines have lifetimes measured in tens of thousands of hours, provide white points unattainable with other lamps, and deliver uniform illumination with little color change over time.
Utilizing mercury-free solid-state technology, LILIs offer instant-on functionality, lower heat output, and faster shutter or pulse-flash response. The output beams are tighter and brighter. LILI fixtures are compact, more energy-efficient, and cost-effective. They also reduce HVAC needs, increase reliability, and lower maintenance costs.
How LILIs work
There are two technologies currently used to create the light emitted by LILIs: RGB laser diodes and Laser Pumped Lamp engines using phosphors.
RGB LILI
RGB LILIs internally mix light from red, green, and blue laser diodes (see Figure 1). This is similar to how LED fixtures mix light from different colored LEDs.
RGB LILIs efficiently blend primary colors without using subtractive filters. By adjusting the relative intensity of the red, green and blue lasers (see Figure 2), colors are changed instantaneously.
Their higher radiance and more beneficial étendue means more efficient light collection and propagation, and the ability to make tighter, lower-divergence beams with brighter spots.
After generation and mixing, the light may retain some of the shimmering speckle which is characteristic of coherent laser light. Simple fixtures may exhibit significant speckle for a new, exciting visual effect, while other fixtures may generate the light with lower speckle and/or internally process away remaining speckle for applications where it may be undesirable.
Laser Pumped Lamp LILI
Inside a standard LED device that emits white light, a deep blue LED illuminates a phosphor, causing it to brightly fluoresce. The blue plus the phosphor-emitted light colors combine to produce white light.
A Laser Pumped Lamp (LPL) engine works in a similar way, only it uses a deep blue laser to pump energy into the phosphor (see Figure 3). Two-thirds of the blue light generates high-intensity fluorescence which creates yellowish light that includes all hues green through red. Combining this with the unabsorbed blue light results in a high-radiance white light (see Figure 4) with excellent color temperature, compared to traditional lamps. The native color temperature can be set at the design phase changing the proportion of blue and yellow levels, or may be adjustable with onboard color correction.
The LPL’s small source size (0.3-0.5 mm) enables precise collimation and high radiance. Higher-power systems may use a rotating internal phosphor wheel to spread the laser heating, preventing thermal damage to the phosphor. While LPL has a theoretical radiance limit, thus far this hasn’t constrained professional lighting applications.
Same safety as conventional lamp-based luminaires
Although the root of LILI light engine technologies incorporates a laser, LILIs do not exhibit laser-like eye hazards.
Conventional lasers are “point sources” which emit thin beams of light. The eye can focus a laser’s light into a pinpoint on the retina. In contrast, LILIs are “extended sources” like conventional lamps; the light is relatively wide when emitted. The eye focuses light from a LILI into a large disc on the retina, spreading out the light intensity. This dramatically reduces retinal hazard compared to the pinpoint concentration from lasers.
The optical hazard of LILIs is recognized by international laser and lamp safety standards (IEC 60825-1 and IEC 62471-5) as being close enough to that of conventional lamps to generally treat the fixture as a conventional luminaire. This is because LILIs typically have a radiance (the light’s angular intensity) 10,000 to 100,000 times lower than conventional laser light show projectors.
Regulatory considerations
For safety purposes, most countries treat LILIs as lamps under the international IEC 62471 family of lamp safety standards. The lamp standards require typical precautionary items such as hazard labeling, and guidance to avoid close eye exposure within the fixture’s Hazard Distance (HD). LILI manuals and labeling indicate the worst-case HD. Some luminaires allow reduction of the Hazard Distance in a safe and dependable manner. No special or additional regulations apply to LILI use in most countries, and audience exposure is permitted beyond the HD.
However, in the United States, LILIs are classified as lasers. The most powerful LILIs, those in lamp Risk Group 3 (RG3), are regulated by the Food and Drug Administration (FDA) in the same way as Class 3B and Class 4 laser light shows. These added regulatory requirements apply in the U.S. for mobile or touring use of RG3 LILIs. Many manufacturers and rental houses may provide education and assistance in this area to streamline U.S. use.
There are efforts in the U.S. to have federal agencies such as FDA and the Federal Aviation Administration (FAA) eventually treat RG3 LILIs as conventional light sources, when their radiance is at or below that of existing high-intensity lights.
The future
LILI fixtures such as those shown in Figures 5 and 6 are an exciting step forward in improving lighting instruments’ light quality and ease-of-use. Like the addition of LEDs to lighting, an improved set of benefits from LILIs are so great, there is no stopping the changes they will bring to the lighting industry. See what excitement and new capabilities LILIs can add to your next tour or installation.
Casey Stack has been involved in commercial laser technology for more than 20 years. Stack served as technical director for LFI International, a leader in worldwide laser display. He was director of sales and marketing for Laser Physics, Inc. a Utah-based manufacturer of air-cooled ion lasers. He served as Vice-President of 3DTL and is a founder of laser display pioneer Lightspeed Design Group, Inc.
He previously held posts as chair of the International Laser Display Association Technical Standards Committee and as a director of the International Laser Display Association. He is a member of the ANSI Z136.1 Laser Safety TSC Committee. Vice Chair of the ANSI Z136.10 “Public User of Lasers” Safety Standard & the genesis of LIPA, the “Laser Illuminated Projection Association.
Stack was the producer and head engineer for the world’s largest laser display at the Grand Coulee Dam in Washington State. He has been involved in projects which have earned more than three dozen international awards for excellence in laser technology.
Today, he is president of Stack Technical Services, Inc. and its division Laser Compliance®, an independent laser product compliance consultancy in Arizona.