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Archive 2015 · Quick & Dirty Flash Sheet Of Light

  
 
jhinkey
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p.1 #1 · p.1 #1 · Quick & Dirty Flash Sheet Of Light


For some basic scientific imaging purposes I need to take the flash output from my Nikon SB-700 and make a fairly thin (10mm or less) roughly planar light sheet. I need the sheet to end up being about 100mm wide x 10mm (or less) thick. I'm imaging some droplets from a fuel injector by using an open shutter of my D800 and the flash to freeze water/air outflow from an injector and want to isolate a thin section of the flow. The flash duration is short enough at the lower power settings for what I need, but I need to shape the light in to a fan.

Any ideas on quick and dirty ways to take the light output and form a sheet of light? Close counts . . .

Thanks for any ideas!

- John



Aug 11, 2015 at 01:53 PM
Paulthelefty
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p.1 #2 · p.1 #2 · Quick & Dirty Flash Sheet Of Light


Snoot and a gobo?

Make a snoot out of some cardboard or construction paper, you can slide it over the flash head. Make it about 12 inches long to start. A shorter snoot will give more light spread, longer will be less.

You can make a cutout in the shape you want and put it over the end of the snoot. As long as you are not too far from the flash, you should have a pretty sharp cutoff. Show us the results!

Paul



Aug 11, 2015 at 11:22 PM
jhinkey
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p.1 #3 · p.1 #3 · Quick & Dirty Flash Sheet Of Light


Paulthelefty wrote:
Snoot and a gobo?

Make a snoot out of some cardboard or construction paper, you can slide it over the flash head. Make it about 12 inches long to start. A shorter snoot will give more light spread, longer will be less.

You can make a cutout in the shape you want and put it over the end of the snoot. As long as you are not too far from the flash, you should have a pretty sharp cutoff. Show us the results!

Paul


Thanks - I was working up to something like that. So far I'm looking at:
- Using paper/cardboard to make a shape that transitions from the rectangular-ish shape of the flash head to something like a 6" x1/4" long rectangular shape to form a sheet of light. In a attempt to collimate the light output I may make the 6" x 1/4" rectangle have two mirrors forming the 6" side so that the light bounces through a narrow channel
- Using a fiber-optic bundle (hundreds of fibers) to transition from the flash output shape to a single line of fibers
- High power LED head that generates a 60 degree light fan/sheet and putting a high speed switch on the DC power supply to make a 1/10000 sec or so light pulse (usually green or red in color). I will be in B&W mode anyways

Thanks!

John



Aug 12, 2015 at 12:23 PM
Paulthelefty
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p.1 #4 · p.1 #4 · Quick & Dirty Flash Sheet Of Light


IMHO you are way over complicating it...

Use the KISS principle, start with a simple cardboard snoot and test it. I think mirrors will only spread the light rather than keep it focused. If you do this often you can make something a little more durable and permanent, but only after some testing.

Unless you are looking for an excuse to play with the optical fibers and some LEDs... Then by all means go for it! :-)

Paul



Aug 13, 2015 at 03:27 AM





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