The String of Light

The lighting industry is a faceted and muti-layered universe. However, the bond that holds it all together is that lighting exists only to serve human kind. To the consternation of technologists and engineers behind the SSL revolution, humans (other than those in the are in the business of engineering and technology) are not particularly concerned with metrics, formulas, or objective measurement. Humans are emotional animals, that respond to light and shadow, who feel before they see, and absorb what they see as real, even when it isn’t. To this end, artistry in light remains a strong factor in the human condition, even when those experiencing it are unable to express its influence, or even acknowledge its impact. This underlying reality is what causes so many metrics addicts to go mad, as they attempt to quantify and control a market that is in fact, uncontrollable. The illusion of control is the fallacious reality we live in as humans. We cannot express our needs for an emotionally, soul energizing, comfortable or pleasing existence in metric terms. Continue reading “The String of Light”

Bedroom Lighting for that Restful Sleep


The Great Blue Light Panic Keeping Some Folks Awake

If you read alarmist comments on the inter-webs about the dreaded “Blue Light Hazard”, you may come away thinking that your TV, tablet, phone, and LED bedside lights are depriving you of sleep. Yes, the spectral power content, including blue light, can produce amplified melatonin suppression that can indeed disrupt your ability to fall asleep. And, yes, LED lights and many LED based displays do produce blue light at the wavelengths of greatest concern. We’ve been all over this, like here, and there have been thousands of other discussions on this everywhere, including in mainstream media – which for the most part get it all wrong. Continue reading “Bedroom Lighting for that Restful Sleep”

No Magic Formula for Quality Lighting

In the discussion of lighting quality, there appears to be a desire to see a simplistic set of performance factors to be met, that can be universally pointed to as “quality”. This is most apparent from fixture manufacturers, who wish to have a set of 3-5 reductive bullet points to indicate their product is a “quality” product. Color rendering is one such factor frequently singled out in this effort, regardless of its relevance to an application.  A quality lighting system is more than the sum of products lumped together into a specification, each defined as quality components, without contextual inter-connectivity. Lighting quality is the result of creating a recipe of approaches, priorities and understanding/agreement that delivers a system that satisfies the end-user occupants, the facility operator, and external influences  to the highest practical level. To this end, I have attempted below to summarize, in the most reduced form possible, the systematic factors that define a quality design.

There is no magic formula for lighting quality. Continue reading “No Magic Formula for Quality Lighting”

YOL 2015 – D13 Navy Bridge Tasca Light

The Navy utilizes red task lighting at night to preserve vision of bridge occupants during certain operational conditions. I was asked to provide a version of the Tasca work light to be used on the bridge for map lighting, to replace incandescent products with filters they had available to them through the GSA. They wanted white light for supplemental daytime use, and red for operational conditions where red light was employed. They also wanted dimming for both conditions. To accommodate this, I added (2) Ledengin 625nm Red LEDs to the standard Tasca head, which employs a Bridgelux 4000K ES COB array, with a custom diffuse optic. One driver is all that was required, with a three position toggle switch that selects white-off-red. This allows one dimmer to be used as well for either mode. In addition to these light output modifications, they also needed the arm system to be extended vertically 6″, with a swivel mount to a bolt down base. I added a swivel lock as well as an adjustment for setting swivel resistance while I was at it, for extra measure. This is now used on two ships, with more on the way. Continue reading “YOL 2015 – D13 Navy Bridge Tasca Light”

YOL 2015 – D5 Techno Task Lighter

Overall height is 19". The base is a salvage item from Goowill.
Overall height is 19″. The base is a salvage item from Goodwill.

I am a task lighting fanatic. I use them everywhere, so am always looking for something new to add to my collection. In this installment, I am addressing the need for a light that is compact, delivers intense light (1,200+ Fc) with no glare or brightness, and high color accuracy. The application is pretty straightforward, from soldering station use where a magnifying glass is used, to fine detail work inside or on the outside of models.  For good measure, I also wanted it to aim at the wall as a photo fill light, or straight up as am ambient fill light, and have a dimmer to allow me to set whatever level I want for the application in hand at the moment.

The wiring and components are left skeletal.
The wiring and components are left skeletal.

With all the practical specifications set out, I decided to let this design be expressive of the gadgetry involved. Let it all hang out. I also decided to incorporate the new Bridgelux Vero LED with its integrated Molex connector, and a Nuventix cooler, just to amp up the tech factor.  This is where things got interesting. The Bridgelux array operates at 33.7V (500mA). The Nuventix cooler at 12V. I am powering the whole thing with a 24VDC wall wart power supply. That meant I needed to employ a boost driver for the LED and a buck (24VDC to 12VDC) power converter for the Nuventix cooler. I used Recom components to attain this, and used a cut up experimenters printed circuit board to connect these two to the power supply, the cooler, the LED and the dimmer control. That’s a lot of wires to find a path for, so I decided to leave them to roam free, let everyone see the components as well.

The lever on the left of the head is the on-off slide switch.
The lever on the left of the head is the on-off slide switch.

This is a style of design I personally enjoy, and have been doing since the 1980’s, where we made little 12V lamps with fiber optics, MR16s, halogen burners, or automotive headlamps, often suspended from structures made of building wire. In this case, the stand I found at a Goodwill. It was a table lamp, whose shade was gone, and socket was cracked. I liked the cast iron base and single post stand, so nabbed it for a dollar and tossed it in the pile with my other finds, waiting this moment to be put to service.

The wiring at the driver and power supply are exposed as well as the mess of wires leading into and out.
The wiring at the driver and power supply are exposed as well as the mess of wires leading into and out.

If you look at the head, the switch is a sliding action, on the left side of the head. Pull it forward to turn it on, push it back to shut it off. A hole in the side of the housing allows you to see the action inside. No, there is no reason for this, other than it seemed more appropriate than an off-shelf toggle or twist switch.

The light on the task surface is at 1,425 Fc, the LED is 3000K, 97CRI.

The head can pivot 180 degrees from down to straight up.
The head can pivot 180 degrees from down to straight up.

YOL 2015 – D1: UV Cure Cube

The Purple Light ‘UV’ Cure Cube

The Cure Cube is used for curing SLA 3D Prints created on the Form Labs 1+ printer. Exposing SLA prints to 405nm "UV" light increases strength and creates a harder surface for final finishing.
The Cure Cube is used for curing SLA 3D Prints created on the Form Labs 1+ printer. Exposing SLA prints to 405nm “UV” light increases strength and creates a harder surface for final finishing.

While not particularly visible to everyone in the SSL universe, over the past few years one area of interest in LED product development for me has been in use of 405nm LED light sources to cure various plastics materials. The advantages are lower power requirements and reduced overall heat in the cure zone over conventional fluorescent or HID light sources. This has been of particular interest in curing fiberglass resins manufactured by Sunrez. The typical demand is for between 200 and 1,000 µW/CM² at 400-405nm wavelength. The use of LEDs allows us to generate exactly that without the waste of visible light, and longer wavelength power the resins are not reacting to. In one project, we were able to replace a 1,500W HID light source with a 120W LED light system that produced faster cure times with less than 10% of the total power, and virtually no heat added to the heat generated by the resin’s exothermic reaction to the curing initiator. Since then, we’ve built 405nm light cure fixtures ranging from 1,200W to 25W.

In this case, I needed to cure 3D prints we generate on a Form Labs 1+ 3D SLA printer, and do so in an office environment without exposing other materials and occupants to UVA light output. The material used in the print process is acrylic based, with chemistry that is photo-reactive to 405nm. The actual prints are made using a UV laser source. When the part is removed from the printer it is washed in alcohol (91% IPA), rested for a few hours to dry the alcohol off, then placed in this cure cube for an hour or more, depending on the thickness of the final component. The end result is a hard first surface for finish sanding or painting, if necessary, and a more rigid part as a whole (less flexible).

The cube is simple, with vent reliefs top and bottom to encourage ariflow. The flush switch on the top cover was created using 3D printing processes for the slider and body, as well as top and bottom cover.
The cube is simple, with vent reliefs top and bottom to encourage ariflow. The flush switch on the top cover was created using 3D printing processes for the slider and body, as well as top and bottom cover.

The cube utilizes a simple aluminum housing, with FDM 3D printed top and bottom covers. The top cover houses a single Recom 500mA driver, slide switch and wiring terminal block on a Tasca LED driver circuit board.

5mm 450nm LEDs with a FWHM distribution of 60º, 25 per side and top (125 total), operating at 20mA each, mounted to custom circuit boards sourced at Express PCB. Each board connects the LEDs in parallel, while the boards are connected in series, resulting in a 500mA, 15.4V circuit, totaling 7.7W. The boards and internal exposed surfaces inside the box were then covered with White Optics 98 matte material to increase total light energy and diffuse The light energy at 405nm is roughly 600 µW/CM².

The bottom surface includes a glass plate where the product sits in order to make any possible stickiness of a part from adhering to the White Optic material below.

The interior of the cube is covered with White Optics 98 material for optimizing light energy re-cycling.
The interior of the cube is covered with White Optics 98 material for optimizing light energy re-cycling.

The housing was powder coated matte black polyester to make clean up easy and the box look nice. The overall interior dimensions of the box are 1″ larger than the total build volume capacity of the printer itself (5 x 5 x 6.5), as any over-sizing is unnecessary. This produces an optimal match between the location of the LED sources and any part the printer can produce.

The Cube is powered by a remote plug mounted 24VDC power converter.

The operation of the box is simple enough. The box is lifted up, the part is set on the base, the box is set over the part, and the light is turned on by sliding the switch to the on position.

Simple and compact is the order of desktop manufacturing, and this fits that model perfectly.

A look into the box lighted up and ready to accept parts.
A look into the box lighted up and ready to accept parts.

Testing so far has shown the cube can cure raw resin from liquid to fully hardened in less than an hour, and strengthens prints in that time or less. The heat generated from this arrangement is so small, there is no chance of any part being warped or affected by the process, other than the desired results of becoming stronger.

For parts to be left unfinished, that are desired to be used over extended periods, we coat the finished parts in either acrylic or polyurethane UV inhibiting clear coat, gloss or matte. This stops ambient room light or daylight exposure from making the parts brittle over time. I am building a second copy of this cube for completing extended testing of samples of the materials we are using to verify clear coat effectiveness, behavior of the print material over long exposure periods, and the behavior of these low cost LEDs over time. A commercial version of this cube could be made using more robust LEDs, but the costs would be significantly higher as well. In the current configuration, the LEDs only cost $0.60 each, so should they last a couple of years in use, replacement of the populated boards is a simple task, while the cost of higher power LEDs would have increased the cost of the entire end-product by as much as three times.

There is also an additional version of this same approach in using Red/Blue light sources for use in plant seedling starts. We’ve found tests with common rye and barley grasses, the time from germination to hearty growth ready for planting is accelerated significantly. Using an enclosure like this allows the plants to be exposed to intense light for extended periods of time (18 hours or more) without polluting the surrounding environment with the ugly light, just as the enclosed cube protects room occupants from exposure the the UVA light. In either case, the cube can be used in any room environment comfortably and safely.

So this gets us off the ground and is D1 of 52 in the series. As I’ve noted at the start, this is an exercise in making progress, and putting SSL to work. This is not a particularly exciting product in and of itself, but it is one that will be used regularly, which more than makes up for its lack of marketing sizzle for the masses – at least in my book.


Retrospective: My First Ever LED Light Fixture – a Collaborative Work

My first LED fixture - 2004-2006
My first LED fixture – 2004-2006

This is my last bit of housecleaning from blogs being shut down, for the archives. KLW

This fixture is my very first LED light. It started life to be a halogen fixture in 2004, that sat on a workbench waiting completion. The first head got so hot from the 50W 12V light source, it was dangerous, so it sat as I decided what to do with it.

In 2005, as LEDs became viable for lighting, I pondered using them to replace the halogen source, but they delivered so little light, the end product was useless as a desk lamp, so it sat some more. One idea was to insert a Lamina BL3000 LED into the head, but the driver was huge, the light output too little, and the heat still an issue.

Then, in early 2006, while at Visa Lighting, Don Brandt (an engineer working with me at Visa, formerly from Emteq, now working at Cree I believe) were talking through ways of applying the latest mid-power LEDs using a simple PCB. We decided to give it a shot and built a board populated by a vendor with 8 Nichia LEDs. The inspiration struck to power these LEDs with two Xitanium drivers, which at the time were un-potted prototypes, so cutting them out of their housing to be installed in clear tubes to show their interiors off was easy enough. Two push-button switches activated the drivers for a high-low effect, and a heat sink was made up of a machined aluminum block installed in the head where the original halogen lamp and reflector once lived. More details and images of this can be found on the Lumenique archives for the Ratchet fixture.

The fixture itself is made of welded steel structure with a brass head and fiberglass tension springs. The head can be raised an lowered with a ratcheting action, staying level at any height. In the end, I left this fixture with the owner of the Oldenburg Group (owner of Visa Lighting) as a parting gift as I moved on to focus on Lumenique and SSL exclusively.

An Update and a Mod

The coming of spring demands a great deal of concentration when you live in an area that is frozen half the year. For April and May this has meant new projects progressing, outside interests fighting for attention, and the progression of older projects resulting in resolution of old issues. Unfortunately, due to the fact that there are those who feel it is their right to knock off ideas they find from others without attribution or recognition, I am struggling with how to proceed with this effort going forward. I enjoy exploring new ideas and sharing discoveries. I despise finding the results integrated into others offerings without so much as a nod to its source.

That said, for this installment of the 12 in 12 project, I focused on making progress in development of portable light originally introduced in the 52 in 52 project in 2010, and a spring project that is personal and fun.

The Battery Project

In week 4 of the 52 in 52 project, I presented this combination table torch/flashlight. At the time, I relied on lead acid emergency light batteries in an effort to create a reliable light for emergency use, using readily available components. Unfortunately, since then, I have found the approach flawed. The batteries were not reliable when connected in series to generate 12VDC, the charging components were not able to keep the batteries conditioned, and the discharge characteristic of the batteries produced an unacceptably short on-time when removed from the stand. Further, the batteries were far too heavy to be practical, and were expensive. Continue reading “An Update and a Mod”

Tasca Uno Test Mule Birthday

The Test Mule passes 12 months in continuous operation.

In the process of building Tasca, there has been numerous iterations, prototypes in metal and plastic, tests to failure, drop and impact tests, electrical and electronic tests, and lighting application tests. As we found what worked, and what didn’t, and collected tooling for components, like the heat sink, I build the first functional products, using production level components. The first one made was what we affectionately call the Mule. It has been lighted 24/7 for one year as of the end of March, or a total of 8,841 logged hours to date. In that time it has been tested under operating conditions, attached to the side of a milling machine head, sprayed with lubricating and cleaning fluids, dropped, dunked, draped with rags under high ambient conditions, and frozen. As shown in the images here, this head has had a few hoods and shields attached to test effectiveness, and the mounting adapter has been changed a couple of times as I’ve experimented with the machined attachment hardware. This head has a thermocouple lead installed, so at any time I can plug it in to see what the temperature of the LED is, while there has been numerous output tests to check lumen depreciation, which has been less than 1% to date, right on track with the LM80 data for the LED (Bridgelux ES array).

This fixture has also been used as a baseline for testing the finished product as it has evolved. For example, we found that black anodizing og the heat sink lowered the LED temperature under identical operating conditions by as much as 10°C. We have also evolved the use of spring washers in the hinge, made small adjustments in the use of fasteners, and added the disconnect power connection to replace the Heyco cord entry – all found from actively working with the product and improving every detail. Continue reading “Tasca Uno Test Mule Birthday”

Tasca Custom Retrofit

I thought a lot about what to focus on in 2012 for this series, and decided that I had plenty to share from regular activities of Lumenique, LLC and Tasca. So, the plan is to select something completed in each of the 12 months of 2012 and feature them here. This will generally be products or projects completed for customers, but may also include a report on research work in process, when it adds value.

January Feature – TASCA Renovar Floor Lamp

This is a refitting of a Dazor table lamp, applying the TASCA lighting head, and adding an extension stand to convert a desk lamp to a floor lamp. The product was commissioned by a customer who provided the table lamp, purchased used. From the GSA and other government markings present on the original, it was obviously from a government facility. The table lamp made by Dazor has been around since the late 1930’s, where the fluorescent lamp version graced the GE display at the Worlds Fair.

For more details on this project, check out the summary and full technical specs at Lumenique 12 in 12 for 2012 – January.

For additional details on how you might procure a similar product from one of your own favorites, visit TASCA.

Also, as an update, the Lumenique Product Center now accepts all major credit cards, making your purchase experience easy and secure.

Stay tuned for additional news and updates on the 12 n 12 for 2012 review, and other interesting SSL information.