Electronics > Projects, Designs, and Technical Stuff
Ultra Short, Ultra Fast LED Flash
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StillTrying:
LED or xenon, 10s of kW is needed for a small close-up 1us exposure.
Marco:
Unless it's some kind of special high pressure Xenon lamp it will have lousy fall off.
JAndrew:
75 Watts is a starting point, it may not be enough light.

If I can get a 500ns 75w flash then scaling up as needed is probably doable.

Xenon Lamps are too slow on the fall off and will create motion blur.

Historically units like these were used.

https://www.ietlabs.com/genrad-1538-a-stroboscope.html

I can pick one up on EBay for ~$300 dollars but the light isn’t as bright as a air-gap. Maybe it’s worth it to try and pick up a couple of these old units rather then to try and cobble together my own.

Sent from my iPhone using Tapatalk
Marco:

--- Quote from: JAndrew on March 09, 2019, 12:23:48 am ---75 Watts is a starting point, it may not be enough light.

--- End quote ---

In that case I'd try to drive one of those 12V 10W COBs with 24V, that should just about get you there electrically (lil higher). Use a MCP14A0302 with a simple ~500p/1K high pass filter on the input to create your pulse from a 5V step (unless the Arduino can generate a 500ns pulse on its own). Something like BUK7M45-40E to drive the COB.

Siwastaja:

--- Quote from: ogden on March 08, 2019, 01:13:23 pm ---
--- Quote from: Siwastaja on March 08, 2019, 12:22:57 pm ---You may even be able to choose the FET so that its Rds(on) temp coeff compensates (at least partially) for the LED Vf temp coeff, regulating the current! This can be a neat trick.

--- End quote ---

Good idea indeed, but you don't have any control over results *and* you shall thermally connect FET to LED. "Standard" and more controllable approach would be to measure LED temperature, set voltage accordingly (assuming that LED V/I curve is known, measured in advance).

--- End quote ---

They tend to be somewhat thermally coupled, because the inductance needs to be minimized as well, so they are close. Of course it isn't exact.
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