Bridgelux has announced the End of Life for the BXRA product. This is the product that put this company on the map, and has been very popular. The company is now hawking its me-too product platforms, along with its proprietary Vero product. I for one will never again consider a proprietary platform from Bridgelux. I am also sure they will experience a significant number of defections as customers find their way resolving the disruption the end of the BXRA platform will cause. I know this, as I intend to help every customer of mine, and anyone else interested, to find a path to other provider products.
Posts Tagged ‘LED’
Tags: 52 in 52 for 2015, Goniometer, LED, Solid-state lighting
While designing cool lighting products is fun and all that, there are other areas of lighting development I am involved with. Whether it is UV curing of resins and plastic parts, inspection lights, or special single spectrum light sources and task lighting, it all comes under the umbrella of lighting for me. In this case, it’s about light measurement, particularly in an easy to use, and simple to set up for gathering data for use during product development, as well as verifying and evaluating design changes in process.
While large scale, accredited LM-79 photometry demands the use of expensive and sophisticated test gear beyond the reach of most organizations smaller than a conglomerate, a great deal of accurate data can be gained from simpler platforms. In the past I created a simple desktop Type C goniometer for customers who were creating small light source scale products.
Since then, I’ve built others with similar purpose for manufacturers setting up in-house test facilities on tight budgets. Having access to a goniometer, where tests and experiments can be carried out as part of in-house design operations can be a very valuable tool. It is also an excellent tool for quality inspections, and establishing variations on test results obtained from accredited labs.
For this specific instance, the requirement was for a system for testing fixtures that might be as large as 24″ in height, and up to 48″ in length, with intensities ranging from small low power sources to high intensity optically focused products. The design is basically the same as for the desktop unit, but scaled up to accommodate the larger scale of the luminaires to be tested.
Note that this is a horizontal Type C, which rotates the fixture around a fixed vertical axis, as well as the horizontal axis. This is a common approach to general lighting products, and can produce Type B results as well. However, since every test fixture is mounted with the light source aimed horizontally, including downlights, the results need to be revolved in creating usable IES files to reflect the actual luminaire orientation in use. Further, with SSL products, care must be taken to avoid including errors in light output that might result from thermal effects of mounting a vertically oriented product in the horizontal position for testing. However, in the 9 years I have been testing fixtures in this type of lab setup, I have not found this to be of significant concern. I have also devised methods for revolving the output data to create the appropriate IES formatted file for end use lighting application studies.
The other aspect of making this type of lab setup affordable, is the use of inexpensive light meters. While those in the business of accredited lab testing will scoff at the idea of using footcandle meters or hand held spectrometers for this type of application, I have found, in back-to-back testing, the results of tests done in house are within a maximum range of between +2% to -10% of those attained by independent lab testing services. Meanwhile, tests accomplished back to back between accredited labs using the same luminiares, has returned variations of +5% to -8%, while the variations in actual installed applications have been far greater due to the variance in surrounding reflective surfaces, condition of fixtures, variations between fixtures manufactured, and other factors outside the confines of the fixture designs themselves. So, while I am not saying this simple lab gear will replace independent test lab results (it won’t), I am saying that, if the operator is careful about setting up the test, diligent in detailing the data, and verifying his/her results, tests completed in-house, during design and between designs, can be reliable and valuable, and a significant cost and time saving advantage. The single largest variable that independent and accredited test labs bring to the table is consistency in process, and independent non-biased reporting for end user application. This is not always necessary for every test completed during and after designs are completed.
I have applied a wide range of meters to these types of test rigs. This includes the $100 Probe Fc meters through the more sophisticated Orb Optronix Spectrometer. The more expensive meters do deliver greater fidelity, the ability to capture multiple reading samples for averaging to eliminate error, etc.. However, I have also found that instruments like those I covered in the meter review, all delivered very similar end results. The use of the UPRTek, or Asensetek meters deliver the layer of reading color over angle in addition to standard footcandle readings, which is very useful in LED fixture evaluation. To create a candela distribution table, I use MS Excel and some simple inverse square law calcs.
For this latest creation, I have includes a rail based meter mount, as well as a rail for the vertical fixture platform. This makes setup much easier, in that moving the meter and the luminaire mount along the rails maintains alignment of the two to one another. Rotation of the luminaire in the vertical and horizontal axis is accomplished using CNC mini-mill rotary tables, actuated by remote control. These can be rotated in increments as small as .006 degrees, with 2.5, 5 and 10 being the most commonly used. The vertical axis rotation table is mounted to a large diameter rotary bearing, which can support 600 pounds.
This latest rig I also includes alignment tools. One is mounted to the center of the fixture horizontal axis (a modified rifle bore sight) aimed at the center of the meter’s receptor window. The other (contractors laser line tool) is located on the rail below – emitting a vertical line for checking the zero position of the vertical axis rotating table. With these two in alignment, the rig is set to go. Mount the fixture using adapter plates to the horizontal axis, set the optical source to the center of the vertical axis, light it up and the temperature to stabilize, and start testing. A typical test for in-house use can take less than 20 minutes after the fixture has reached its operating temperature (2 to 24 hours to taste).
There are other small additional components involved. I personally like to connect the test products to a reliable power source. The easiest way to gain this is using a UPS generally used to connect computers to. They are affordable, and offer much more reliable and consistent voltage output than wall plugs do. I also add temperature measurement (a simple Amp two position meter works for most applications – one for ambient, one for fixture hot spot), and in some case room heaters or coolers to attain a stable ambient temperature where this is not inherent to the lab itself.
So that’s it. An affordable in-house Type C test rig. Not a light source, but related to development of them. I use a similar setup for my own product development, along with a cannon style integrating chamber, a small integrating sphere, and some other cobbled together test rigs that have proven to be accurate for relative comparison of results to a known standard.
Tags: 52 in 52 for 2015, LED, LED plant light, LEDs, Solid-state lighting
The use of LEDs in agricultural applications is expanding along side visual light and light cure technologies. The technology is even more compelling here for its reduction in energy consumption and lack of heat in the light pattern. The key element of LEDs in this application is the ability to create a specific spectral power profile, with none of the peripheral light unnecessary to get the job done. The light plants need is not the same as human vision. In fact, it is almost the opposite. While we humans with our juice camera eyeballs respond to light in the yellow-green spectrum to see by, our blind little green friends use light in the red and blue ends of the spectrum to activate various chemical reactions to generate food, build cells, and dispose of waste. (more…)
Tags: 52 in 52 for 2015, LED, LED Art, SSL
Actually, this started as a rough lab test experiment applying thermal transfer pipes (copper pipes filled with water) to move heat from an LED platform to a simple back plane surface. The experiment included bending the pipes, soldering them using silver bearing solder, and operating the system at various angles to see the effect these had on performance. Somewhere along the line, an idea formed of making this into a wall piece, creating an industrial-chic, which led to adding a cut down reflector, and using the SLA printer to create an industrial tech representation of a flame rising from the reflector. The square cut in the diffuser aligns with the connected graphic on the back plane, and the stenciled number 15 simply represents the year.
The driver is housed in the FDM printed housing below the light source on the back plane, with a dimmer. Total power to the source is 19W, while the LED is 95CRI 3000K. Note that the overly red hue to the background, and slight magenta appearance of the white graphics are all issues with the camera dealing with the red-enhanced LED source, which creates high CRI, with a 90 R9 value, but in reality is a distortion of spectral power that the human eye does not readily see – but mid-range camera image sensor algorithms cannot accommodate.
Tags: 52 in 52 for 2015, LED, Motorcycle LED
With the arrival of spring, I am once again longing for a rip on the open road and a little wind in the face with the rap of a high strung 4 banger UJM hot rod under me. But, let’s apply a little context as it relates to this years 52/52 project. While the previous works pursued in 2010 were focused on off-the-cuff works, with the majority being task lights, this year I am not remaining within those narrower bounds. For 2015, I’m going to present application of LEDs and SSL technology wherever I find a place for it, in actual applications, including, but not limited to lighting applications. There is a simple reason for this. My interest and pursuit of solid-state lighting integration is not bound to architectural lighting, it also includes UV curing and artistic application and, in this case, recreational uses.
Over the last several years I have been on a quest to convert all of the incandescent lamps out of an ongoing WIP motorcycle project. It seemed simple enough, as there are many made in Asia LED products sold through motorcycle retailers. The problem is, when you dig into them, they are either complete junk, weak performers, or did not fit the design of the project in hand. Nowhere did this become a major challenge more than the headlight. Motorcycle headlights serve two purposes – to light the way at night, and to create a daylight presence that catches the attention of motorists who are blind to bikes (some of the more mentally challenged motorists in this world see what they expect to see – which are cars – they are literally blind to seeing bicycles, motorcycles, animals, etc… so run over, drive in front of, and crowd these invisible obstacles out of their path.)
Compounding the issue of effective forward lighting, motorcycles, especially older ones like the one I am working on (1979), have fairly wimpy electrical charging systems, so voltage delivered to headlights tends to sag, delivering less light and warmer CCT’s. It seemed a perfect fit for application of LEDs operated from a current control driver, as this could eliminate the output droop from voltage drop, as well as increase the CCT of the light output to optimize visual performance and presence on the road. Unfortunately. sifting through the myriad of garbage being sold as LED H4 lamp replacements took some time, and included evaluation of several alternatives, many deemed useless scams. I discovered that without some form of cooling system, the LED bulbs either were not delivering enough light, or were operating at such a high temperature, they were likely to fry themselves and fail in less time than the halogen lamp I sought to rid myself of. However, over the course of this winter, several new lamps came into the market that are looked promising. While not yet perfect, I found one that not only fit well, but delivered more light than the original halogen lamp. I was finally able to finish the LED conversion project this week, ending a two-year effort at last. The new system presents a load of 12W or 14W, replacing the 55/60W H4 Halogen lamp, while measured light output is increased by 15% (at full battery voltage, significantly more when the battery voltage is lower). The lamp includes an active heat sink and fan to keep it cool, which I found in bench testing worked surprisingly well. In fact, the thermal slug-to-heat sink is very similar to a design I have used in several product designs with similar optical demands. Not really wild about the fan, so will keep an eye on that, but its necessary to produce the output and longevity I was looking for.
In addition to forward , the headlamp integrates the turn signals. At the right and left side are amber LEDs embedded into the lamp reflector, which serve as turn signals and emergency flashers. At the center is the H4 LED conversion lamp, which incorporates a current driver, cooling fan, and controller circuiting that maintains full light output, even when battery/system voltage drops to as low as 9.8V. The tail-light includes red LEDs and a controller that and white LEDs with a clever resister/bypass circuiting that lights all of the LEDs at a lower intensity for standard tail-light function, then brighter when the brake light is active. The rear turn signals are a Frankenstein creation of mine that includes custom interior bits to integrate proper Amber LEDs into the bullet shaped housing originally designed for a small incandescent lamp – I was unable to find any off-market products that had the brightness I wanted.
The turn signal conversion to LEDs created an issue with the flasher system. Flashers in older vehicles are nothing more than a thermal cutoff switch that auto re-sets. When on, an internal leaf or coil heats up, breaking the circuit (off state), which then cools quickly and re-connects (on state). These are “tuned” to operate with a closed circuit, which an incandescent lamp provides. The load of the lamps in the circuit creates a resistance, which the flasher is tuned to, creating a flash rate based on how much voltage is present in the system based on how many incandescent lamps (acting like resistors) are in the circuit. This is why the flashers blink faster when a lamp is lost – increasing the voltage in the flasher “heater”, causing it to heat faster, thus, blink at a faster rate. Well… LEDs do not create a closed circuit for this process to work with. This requires either placing a resister into the system to create a closed circuit load similar to the original incandescent lamps (seems kind of silly), or replacing the flasher itself with some other modulating device that can blink without the closed circuit connection. Motorcycles present a few odd wiring flukes that complicate this, so the solution requires a little custom hacking. In my case, I was able to find a flasher kit from an on-line electronics kit outlet, that was then modified to work within the bikes wiring system. Problem solved.
In the end, the compelling reason for this entire conversion included several desired advantages. Incandescent lamps on vibrating motorcycles is a bad thing, LEDs don’t suffer this malady so no more constantly burned out bulb issues. Incandescent lamps present a load to relatively feeble motorcycle power and charging systems. The LED conversion reduced the load on the charging system and battery system from 94W to just 26W total, which allows the charging system to be used by the ignition system, at a more constant output voltage – while delivering brighter lights all around, and decreasing the time it takes to recharge the battery after starting. The LED headlamp conversion also increased the headlamp CCT from 3150K to 6500K, which is more visible during the day to numb-skull cage drivers, and increased visual performance while riding at night.
With this conversion, I am now down to just a few CFL and T8 lamps in the shop and garage, and just (2) halogen/filament lamps remaining in my home and work spaces. These will soon be gone as this years 52/52 projects puts them in the cross-hairs. Stay tuned….
Tags: 52 in 52 for 2015, Hathcock, LED, LED Art
My involvement in lighting was born from a graphic arts and photography background, so imagery remains a core interest of mine. Design 9 was inspired by a particular image of a rifle scope being shot through by another rifle, creating an eruption of glass that caught the light. We’ll get to the reason this was being photographed, and why in a moment. First, what intrigued me was how high speed photography today catches moments in time that are beyond human comprehension. We are blind to most wavelengths of energy, we know that. But, what we seldom recognize is that the slowness of our visual processor is such that we comprehend only a fraction of what is actually happening around us. Time lapse and high speed images catch a fraction more of this missing perception. Time laps images capturing the blooming of flowers, showing that these organisms live in a slow motion universe outside our comprehension. High speed photography shows us the micro-moments that occur while our feeble brains process sampling of bits.
High speed video images of bullets blowing through fruit, and in this case a rifle scope, capture the impact and movement of an object weighing a few grams, traveling at 2000 feet per second, revealing the release of the energy this creates.
Now to the specifics. D9 is a conversation piece, meaning it is designed specifically to start or incite a conversation, even an argument. The visual effect I was attempting to capture was This particular image from an episode of the Mythbusters (History Channel property). They were testing whether the legend of Carlos Hathcock shooting a sniper through his scope in a legendary incident in Vietnam, was mechanically possible. In this, they placed several scopes some distance down range and shot rifle rounds through them to either deem it plausible or busted.
Conversation Note 1: The test was flawed in that it did not test period correct, North Vietnamese optics. First, the optics of that day were not variable, thus were far simpler than the compound optics tested in the episode. I’ve dismantled several scopes over the years, and can confirm that the internals of modern scopes would be impossible to penetrate. In fact, the scope used in this design took a great deal of effort to “disassemble” with a steel rod and hammer, as the center section (area under the turrets) is very dense in compound lens segments of very small diameter. Fixed, simpler scopes do not include this denseness. Further, the tests did not represent the actual energy of impact accurately, as the distance of the shot was less than 50 yards, let alone 500.
Optics of Discussion. In thinking about this design, I was captured by the various “optics” involved. The optic of the angles and geometry involved in the shot, the optics of the and within the scope being shot. the optics of the shooters scope, the optical challenge of shooting through a tube that is 1″ in diameter, with a thin shell presenting an entry target of 1.5″, from a distance of 500 yards (a little more than a quarter mile), the optic imagery of the bullet passing through the glass, and the unavoidable optic of the repercussions of such an accomplishment. I was also captured by the reaction of the glass, and the release of energy in both the entry and exit directions (shown in tests by others) when the shot is made. Its all very intriguing, which is what makes it such a compelling story / legend.
Conversation Note 2: The scope Hatcock used was an 8 power Unertal and the distance the shot was taken from was 500 yards. The claim is that he saw a glint of light from his target, which he used as a point of aim. The optical field of view of an 8 power scope at 500 yards is around 75 feet. Thst means he was able to recognize and place a target that was 1/600th the field of view, smaller than the width of the cross-hair wires inside the scope of the day. While not impossible, this is on the very extreme edge of it.
Conversation Note 3: The glint from the targets scope indicates the sun was behind Hathcock, and that his target was aiming at him directly into the sun. With a field of view of the same 75 feet, he was not only fighting the glare from the sun through optics with marginal clarity, he was seeing Hathcock in the shadows at the same 500 yards? This seems the most unlikely aspect of this story.
Conversation Note 4: At 500 yards, for the bullet to travel through the scope tube, the angle would have to be essentially perfectly in line with the scope axis, as any deviation from that angle would result in deflection defeating the the result. That means zero wind drift effect, and zero angle of inclination between the shooter and the target. This seems optically possible, and practically on the verge of impossible.
Conversation Note 5: The bullet would need to not only travel the distance of 500 yards but still have enough energy to drive through the scope itself. At that distance, a 175 grain 308 bullet would still be carrying an energy of 1167 ft. lbs of energy, about the same as a 22 LR bullet at point blank range. This seems enough energy to drive through the scope glass. Whether or not there would be enough energy or enough of the bullet itself intact after blasting through the glass is another story. It is possible that the lower energy state is what kept the bullet from exploding when it struck the scope, which renders any tests done with higher energy states for verification totally invalid.
That all said, Hathcock was one of the best shooters of the time, decorated many times, and recognized for his contributions. Nothing here is intended to defame that. His credibility is what makes this whole story so intriguing, as he had no reason to fabricate such a story at all. I have seen some truly jaw dropping shots taken by marksman in my own 40+ years of shooting to know that there are people who know how to place shots with precision beyond human comprehension, high speed images or not. The shot is not impossible. The bullet, once loosed, was going to travel through a spot in space down range equal to its physical diameter of .308″. That could have, indeed, been within the diameter of the objective bell opening of a scope.
My goal was not to prove or disprove the legend. My goal was to create a static object that presented the visual, or optics, of the composite moments of the bullet traveling the last 24″, and the spray of glass that would have resulted in both directions. The glass spray was created by printing two structures on the SLA machine in transparent material, then coating those with clear urethane, which was then dusted with shattered glass. Internal to the scope are 2 LEDs aimed outward. The top turret cover is a dimmer knob, while the section of rifle below, printed on the FDA machine (sanded and painted) houses the driver and a military style on-off push-button switch to cap the whole design aesthetic.
Tags: 52 in 52 for 2015, LED, Solid-state, Solid-state lighting, UV Cure LED
As demonstrated in D1 of this series, LEDs and solid-state technology are changing more than general illumination. Other instances of applying near UV LEDs with emission to cure light-cure resin composites. We have applied this to replace Metal Halide light sources that require 20 minutes to start-up, and are skin frying monsters. LED cure lights are also more predictable and focus-able than natural light, and can be applied indoors, and less bulky and more powerful than fragile fluorescent cure systems. LED sourced cure lights are now used in printing, dentistry, and commercial production of resin-based composites. We are also applying this on small and large scale applications from the very small (like D1 SLA curing) to larger scale units for curing large objects, like fiberglass repair of boat hulls, custom automotive body panels, and low odor repair of fiberglass bathtubs and shower floors. The use of LEDs produces instant-on high intense light, with much less power, significantly less heat in the lighted pattern, less exposure to hot surfaces, and contain none of the damaging ultraviolet light that does nothing to enhance curing, but is harmful for operators. The use of UV initiated resins offer the advantage of extended shelf life as there is no catalyzed resin to harden in the container and less odor for use indoors. An update with new images and details will be posted here when available.