Has any one used the
Osram SFH 4230
and if this would be suitable for a DI setup, if not what do you recommend…

Also what QTY of these would we need as they are crazy bright! (screen approx 50")

Thx
JR

Have a look at the safety advices in the spec-pdf:

“Depending on the mode of operation, these
devices emit highly concentrated non visible
infrared light which can be hazardous to the
human eye. Products which incorporate these
devices have to follow the safety precautions
given in IEC 60825-1 and IEC 62471”

Oliver

I think they’re roughy ten times as powerful as normal LEDs, so a few of them would suffice.

looked up the specs and they are rated at 170 mw/sr ... thats not much brighter than the SFH 485’s (160 mW/sr) ... i would suggest one led every 2 to 3 inch along the two longer edges of the acrylic and try n offset the two parallel strips so you have one led per inch / per 1.5 inch along the length alternating each side.

@preshape… any IR led above 5 mW is hazardous to eyes if looked into straight.. but in FTIR you don’t do that since you trap it in the surface. DI is actually more hazardous on that front since you beam em straight into the user’s eyes.. so a good diffuser always helps.

deej - 09 April 2008 06:15 AM

looked up the specs and they are rated at 170 mw/sr ... thats not much brighter than the SFH 485’s (160 mW/sr) ... i would suggest one led every 2 to 3 inch along the two longer edges of the acrylic and try n offset the two parallel strips so you have one led per inch / per 1.5 inch along the length alternating each side.

However, the SFH 485’s half angle is 20°, the SFH 4230’s half angle is 60°. You have to take that into account when you speak of “brightness”.

For the same $$$ you can get more from T1-3/4 housings (especially for synchronized pulsed driven designs).

A greater number of LEDs will give you better, much more even, coverage than fewer and brighter LEDs.

Also keep in mind that larger dispersion angles result in more losses due to big increases in radiation reflecting off the edge rather than refracting through it. You can modify the dispersion by placing a small lens directly onto the silicone surface of the housing. Or at least directly couple the Dragon’s silicone surface the the panels edge without the losses of an air gap.

But… If you have your T1-3/4 right next to each other, need more power and can not fit any more on the edge, then Dragons are a solution for sure.  Or given a blank check, tightly spaced Dragons (with heatsinks of course) would bitchin.

*****
Also, while the Dragons dissipate much more heat than T-1 3/4, this is particularly important when running continuously. But of course better designs are PULSED! So lets look at the real numbers…

Dragons SFH 4320 are rated at 440mw total radiation flux at 1.0 amps
Its peak pulse, or surge, is rated at 2.0 amps (1ms), assuming linearity, for a maximum pulse of 880mw of radiation.

SFH 485 are rated at 25mw total radiation flux at 0.1 amps (20ms)
Its peak pulse, or surge, is rated at 2.5 amps (10us), assuming linearity, for a maximum pulse of 625mw of radiation.

But of course there are some differences between 1 millisecond pulses and 10 microsecond pulses. Perhaps Dragons can actually pulse higher currents for briefer periods of time. Assuming the same connection wires (same manufacture) it should at least match the 2.5 amps and produce 1100mw for 10 microseconds. OK, so nearly twice the output of a SFH 485 in pulsed mode, but at >10x the price!!!

But the shutter of your camera likely only goes down to 125 microseconds (FireflyMV) . The Dragon could still pulse at 2.0 amps and the SFH 485 would likely be reduced to some number to be determined since it is not spec’d. I’d guess to 1/3 the radiant flux of the dragon, but at >10x the price!!!

However, if you factor in the Dragon’s potential for better optical coupling, maybe get up to 6x (???) the “radiation in the panel”. But it would still be wiser to first get much greater gains by moving away from continuous mode drivers to “pulsed drivers synchronized to a very short global shutter”.

Surface mounted housings with dies floating in silicone really are nice, too bad they are so spendy.

Yeah, this posting should have been better organized.

Almost forgot, anyone know of good IR blocking safety glasses