For those that are just joining us, you can get up to speed on this Xenon Projection + LED lighting system by Luke (Liveforphyics) by reading Part 1 here.
Some of the comments towards this project on various forums have been disheartening. It’s a strong reminder of why nowadays I rarely participate… I’d like to [...]
For those that are just joining us, you can get up to speed on this Xenon Projection + LED lighting system by Luke (Liveforphyics) by reading Part 1 here.
Some of the comments towards this project on various forums have been disheartening. It’s a strong reminder of why nowadays I rarely participate… I’d like to personally thank Luke for taking the time to share this project with us all and I hope those reading this can take something positive away from his hard work.
Q&A Continued
GBD: What cars did the projectors you are using come from? Are they OEM or aftermarket?
LFP: These projectors are OEM parts removed from the headlight assemblies of BMWs. I purchased them all ready removed from the headlights of wrecked cars. Retrofit Source provided great service with my different orders of projectors to find which I liked best. These units are manufactured in France by Valeo, and are very economical for the performance they offer.
GBD: What lights showed promise from a spectral perspective?
LFP: I worked with a wholesaler to test the different brands of 8k, 10k, 12k, 20k and 25k Xenon bulbs they offered. Both flux and spectrum varied widely between the different bulbs. I ended up using one of the more pricey company’s 25k blue and 25k purple for some of the spots, and a different manufactures 10k bulbs for the areas I wanted to appear more white. The 25k purple bulbs give a color I’ve never seen in reef lighting. I previously used some of KZ’s Fiji purple bulbs in my T5 lights, but this purple is much more vivid. The lamps I chose all showed strong 430nm peaks, and other longer wavelengths, which was something I wanted to help stimulate chlorophyll A.
GBD: What type of longevity do you expect from these bulbs?
LFP: Only time will tell. Xenon bulbs do have a unique difference from other forms of lighting. MH and T5 bulbs create UV light inside the bulb, and then use this UV light to stimulate phosphor coatings to fluoresce and emit light in the visible spectrum. Degradation of the phosphor coatings are commonly what causes the output of a bulb to shift spectrums and fade with time. Xenon arc lighting ionizes a blend of gases into plasma which directly emit the wavelengths of light. No phosphors to fade over time, but they do have electrodes that wear with time. The manufactures typically give lifespan ratings in the 3,000-5,000hr range, but I rarely trust these sorts of hour ratings with lamps.
Fortunately, I was able to make a friend of the wholesaler and was able to purchase the bulbs at some very good prices. To re-lamp my previous setup, I would spend about $600 on KZ T5 lamps and MH lamps. Re-lamping my current setup will cost under $200, and take very little time to swap bulbs.
GBD: Some PAR is expected to be lost by passing through the glass of the projector lens so what type of efficiency gains are we seeing by the focusing of the light?
LFP: Excellent question. I’m going to try to keep from getting excessively geeky, but I think I can make a comparison that will help explain. When you turn your headlights on or a flashlight on outside in daytime, you often can’t even see the light you are creating. However, if you turn on a laser pointer, even though it’s making only 1/10000th of the light the headlight bulb produces, you are able to see it. This is due to the ability of collimated light to maintain intensity over long distances.
The projectors feature an optimized reflector to feed light into an aspherical projection lens. To give an idea of the degree of collimation possible to achieve with a lens like this, I experimented making a flashlight using a single LED and an aspherical projection lens that throws a visible spot for hundreds of yards. I actually chopped down and re-located the lens closer to the source in some of the projectors to lower the intensity and spread the light out along a wider area. Using projection technology, it would be possible to mount aquarium lighting 10ft or more above an aquarium and still have higher lighting efficiency than conventional reflector systems mounted at normal heights.
GBD: On the light rack there are white tubes around the LEDs, what purpose do they serve? Are you using any additional optics?
LFP: The white tubes are PVC couplers mounted with an adhesive. They serve two functions, one of them being very important to me– I have eyes that are sensitive to glare. I quickly get a headache in a room with visible open ended MH reflectors. I also have an HD front projection movie theatre setup in the room connected to the aquarium room. The shields serve to eliminate unwanted glare and stress on my eyes, as well as keep the ambient light added to the room down to a minimum so I can still use the projector without turning off the tank lights.
The second purpose is to protect against me knocking off each of the delicate optics mounted onto each LED. I’m using 20deg acrylic collimation optics on the perimeter LEDs to ensure a tight beam that doesn’t hit the glass. For the inside LEDs I switched to parabolic reflectors to help blend the excessive columns of blue spears look that the collimation optics produced. It was neat, but it was organized in a grid pattern that looked very unnatural.
More is on the way in Part 3. I heard something about PAR numbers…
