Where to find embedded developers for start-up?

I would say the first thing would be to have contact details on your website, and to give a rough indication of your area.

I would be happy to talk to the likes of you, presumably under a NDA, but you'd need to be at least in the same country!!

A sample of one (a Fenix AAA-cell LED flashlight that's on the workbench) examined with a qualitative spectroscope [*] shows an apparently continuous spectrum from about 420 to 680 nm, with just a little visible dip between about 480 and 490. No lines.

The fluorescent desk lamp, by contrast, shows the typical strong mercury emission lines, plus a doublet around 610.

The LED does seem to allow some UV to pass; assorted plastics on banana jacks and such that do fluoresce under UV look a little "enhanced" with the flashlight.

[*] It's an "educational toy" but actually works pretty well for emission and absorption features that are distinct enough to pick out by eye. From these guys, among others, and it's cheap enough to satisfy curiosity about what common spectra look like.

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Rich Webb     Norfolk, VA

(stuff about LEDs)

Interesting!!!! Ordered! Thanks.

Light and color is indeed fascinating topics!

There are some claims here that this type of light is useless, won't work, etc., but we are well beyond that. This is not a theoretical exercise, the development has been going on for quite some time and the results are excellent.

The interesting part is of course _why_ it works. Color theory is sometimes quite counterintuitive.

One interesting aspect is of course additive color mixing where yellow can come either from a light with a peak wavelength of, say, 580 nm - or from two light sources, a mix of red (650 nm) and green (510 nm). The eye will not perceive a difference. Think about it. The screen you are looking at right now has red, green and blue pixels (most likely from a LED source). How is the screen able to display yellow?

Another issue not discussed here is that the color space of a camera is a lot smaller that the color space of the human eye. (monitors have a still smaller color space and most printers way smaller that monitors). There is really no need to generate light beyond what the cameras RGB sensor is able to capture.

Anyway. If anyone is interested in knowing more, and maybe participate for pay or sweat equity, I'd love to hear from you! I've updated contact info on the website. My email address is mhjerde at gmail dot com.

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So you are trying to create a uniform light source, to illuminate objects/scenes that are going to be captured on devices using film, tube, comos, ccd, a myriad of other sensors.

Let's see for video work there is such a thing as a standard illuminant which is not linear, which these are already tuned to work best with. This used to be D62 then changed to D65, many years ago to match an overcast sky. The power distribution spectrum of 6500K.

This standard illuminant is the basis of many digital sensing devices, from line at a time scanners through to digital SLRs.

Are you going to change the sensors, gels, filters, mosaics as well? Let alone the chromaticity of lens pass this.

Are you just trying to make yet another special effects lighting for certain effects or for general lighting of image capture.

On some devices the 25kHz will produce beat patterns or other effects on line to line through the image.

I think this a problem that does not appear to need fixing. It has been worked out for over 50 years as most cameras are tuned to take pictures in daylight outside.

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Paul Carpenter          | paul@pcserviceselectronics.co.uk
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I've worked with slower rate PWM and there's an analogous problem: if the light source moves, the colors can separate as the differently-timed, differently-colored flashes come to occur at different places.

Mel.

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Thats true but what happens when you use that light to illuminate a target that reflects 580nm strongly, 510 slightly and 650 weakly? With white light it looks yellow with a hint of green and with the led source it looks green. Lamp makers have spent millions over the years to try to get correct colour rendering from their lamps and still its not quite right.

Think about it. The screen you are looking at

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That's what struck me first. Given the name, I'd guess you were from Scandinavia or perhaps the Netherlands. But given the lack of information about where you are based, I'd assume you were American (since Americans regularly forget to say where they are posting from).

If you are in Norway, or near enough to Norway, I can give you information about my company as we could probably help with development and production of your system. Let me know if that's of any interest.

Try clicking the "about this blog" link, seems they have 2 locations, one of them sounds in your target area. ;-)

Both locations out of our area unfortunately.

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Hi Morton

As you're in London - you should head to the plasa trade show, running at Earls Court at the moment - loads of LED lighting there, and some of it may be similar to what you're trying to achieve.

Regards

Martin

Cameras use other protocols to communicate with lights, they are proprietary and different for each manufacturer and a real hassle.

I guess you could say that this light is different from a stage light the same way a truck is different from a sedan. This is a small battery powered light. The optics are intended for photography, control of light properties is done on the unit itself, or from the back of the camera.

Spectral power distribution and fine control over correlated color temperature is more important for photography than it is for stage lighting (I assume :-)). This light understands exposure times and frame rates and is able to modulate parameters during individual frames and over a series of frames. It is like High Speed Sync on, well, speed :-) It can measure and mirror the color temperature of ambient light.

You are right that there are colors that fall outside the color triangle you get by colormixing this or any kind of tripple cromaticity luminaire. Deep violet is probably a good example. I guess this is more of an issue for stage lighting where you may want a very saturated effect color? Photography is 99% about controlling white light and the ability to emit a particular color is icing on the cake.

Morten

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Me too.

Looks like he's in my country

OP - You have mail

tim

Beware of all the patents on ideas which are obvious to practitioners not in the field.

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