The killer red diode......warning

[matt_man10]

Hey Krutz,

It may be worth remembering that although 750 Lumens doesn't sound a lot it's still a heck of a lot of light it's also worth (Forgive me if i am a little rusty here it's been almost 10 years since i did this in collage) noting that Lumens are a usually a measurement of light as perceived by the eyes not it's actual power output.

A quick look at the data sheet shows that the red LED will put out 4.2 watts(radiometric power) of red light tho only have a luminous flux of 750 lumens whilst the green module is putting out just 3.3 watts in radiometric power whilst achieving a luminous flux of 1550 lumens it's the same reason that lasers with different wavelengths but the same power output have vastly different percieved brightnesses For example two 100mw lasers placed side by side one 650nm (deep red) and one 532nm(green) the green laser should on average appear arround 8 time brighter even tho both outputting exactly the same radiometric power (eyes are funny things arent they?)

MechEng3... i don't recommend hitting it with 13amps as you will very rapidly see a little puff of magic blue smoke and will have some lovely Abstract molten silicon artwork to admire , the most the datasheet recommends if you want to drive them continuous wave is 8.1Amps and it should still put out 2.3w of red light

[Diachi]

Yes, these are hugely powerful and potentially dangerous LEDs. I've heard of LEDs similar to this melting holes in CD cases with the output straight from the die.

[OzOnE]

Hi,

I hope I'm not hijacking this thread, but I thought I might share a bit of info on my LED projector experiments...

@VJ - those big LED's won't be terribly efficient when used in a DLP projector. Also, it's very difficult to get rid of the pattern of the emitters from the projected image (this is why the Phlatlights have a uniform output).

The big problem with larger LEDs is you come across the "etendue" problem.... I've played with retrofitting LEDs into DLP projectors for a few years and the LEDs need to have a surface area the same size, or smaller than the DMD chip itself.

The light rays have to exist between a specific angle, and this is generally related to the size of the DMD chip - Any light rays outside this area cannot be collected by the chip.

At least I think this is what etendue basically means, I never fully understood it?...

http://e2e.ti.com/blogs_/b/dlp_mems_...ue-i-care.aspx

I wrote a bit of Verilog code for an FPGA about four years ago which simulates the DLP colour wheel and switches the RGB LEDs. This allows the colour wheel to be completely removed without the projector realizing.

It also switches the LEDs at exactly the right time to match the original colour wheel segments and outputs a signal for the opto sensor (or colour sensor) to keep sync with what the projector is expecting.

You can adjust the timings to mix the different LED colours for each "segment", but it usually looks worse unless it's just plain R/G/B/W etc.

I've messed around with Luxeon K2's / Lamina Ceramics / Edison Opto / Osram / Seoul P7 / cheap eBay stuff (and anything else I could get hold of), but I'm now using some LedEngin LED's (which were the brightest small-area LEDs for the price about a year ago until the PhlatLights went public).

The projector isn't amazingly bright, but far better than any of my previous attempts. It gives a perfectly watchable image in a darkened room (a 5-feet wide image is fine).

I had to use some small polymer lenses and a dichro cube from an old Sharp LCD projector to combine the RGB beams (need to squeeze the beams into the same angle because of the etendue issue). A convex lens from a Compaq MP1600 is used to focus the "white" beam onto the light tunnel.

The projector is the IBM iL2215 (InFocus LP335 clone). It's currently not running because I needed to steal the FPGA board for another project. I also think I broke a wire bond on the Red LED.

Here's a photo...

http://img31.imageshack.us/img31/9523/file0085.jpg

It used to have a huge tall CPU heatsink underneath, but didn't really need it (requires a slow running fan though). It now has an Xbox 360 GPU heatsink, as it obviously wasn't helping the Xbox much.

OzOnE.
Oh... and watch out - these LEDs need similar respect to lasers! The high flux density can burn through your brain just as easily. (and your Blues Brothers shades won't help much).

[flecom]

wow thats pretty neat, I always love to see people hacking hardware

[Stoney3K]

You said the LED was mounted on a TEC assembly. Has anyone thought about harvesting the TEC?