Comments on: Laser head patterns http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/ the best thing i learned today Fri, 11 Sep 2009 21:09:51 +0000 http://wordpress.org/?v=2.9.1 hourly 1 By: Brandon Roy http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/comment-page-1/#comment-525 Brandon Roy Fri, 30 Nov 2007 22:10:38 +0000 http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/#comment-525 Kind of related... I learned that lenses do a Fourier transform. I thought that was pretty cool - so if you have a spatial pattern of alternating black and white lines at a certain spatial frequency, there is a point behind the lens where you get a dot, related to that frequency. And if you have interleaved lines of different frequencies, you get multiple dots! All of this is hearsay, but I think its true... Kind of related… I learned that lenses do a Fourier transform. I thought that was pretty cool – so if you have a spatial pattern of alternating black and white lines at a certain spatial frequency, there is a point behind the lens where you get a dot, related to that frequency. And if you have interleaved lines of different frequencies, you get multiple dots! All of this is hearsay, but I think its true…

]]> By: Rachel http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/comment-page-1/#comment-522 Rachel Fri, 30 Nov 2007 04:12:25 +0000 http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/#comment-522 Damn, now I wish I'd done the <a href="http://socrates.berkeley.edu/~phylabs/writeupPDF/HOL.pdf" rel="nofollow">hologram lab</a> in physics lab! Who knew I was actually going to use it some day (for a very loose definition of "use")? <a href="http://laser.physics.sunysb.edu/~dbennett/optics2/optics2.htm" rel="nofollow">This page</a> on computer-generated holography is kind of hilarious. Silly grad students. Damn, now I wish I’d done the hologram lab in physics lab! Who knew I was actually going to use it some day (for a very loose definition of “use”)?

This page on computer-generated holography is kind of hilarious. Silly grad students.

]]> By: Anita http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/comment-page-1/#comment-521 Anita Fri, 30 Nov 2007 01:23:20 +0000 http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/#comment-521 Ah! Thanks to Rachel's hints, and a suggestion by <a href="http://web.media.mit.edu/~brown/" rel="nofollow">Judy Brown</a>, whom I met today, I found a page that describes the phenomenon in several parts: <ul> <li><a href="http://www.repairfaq.org/sam/laserdio.htm#diolppm" rel="nofollow">Laser Pointers that Produce Multiple Patterns</a></li> <li><a href="http://www.repairfaq.org/sam/laserioi.htm#ioidpg4" rel="nofollow">Diffractive Pattern Generating Optics</a></li> <li><a href="http://www.repairfaq.org/sam/laserioi.htm#ioidpg0" rel="nofollow">Diffraction Gratings</a></li> <li><a href="http://www.repairfaq.org/sam/diffract.gif" rel="nofollow">Diffraction Grating Principle</a></li> </ul> So this is like a hologram? I've gotta find a better explanation, but that will have to wait until the weekend. Ah! Thanks to Rachel’s hints, and a suggestion by Judy Brown, whom I met today, I found a page that describes the phenomenon in several parts:

So this is like a hologram? I’ve gotta find a better explanation, but that will have to wait until the weekend.

]]> By: brent http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/comment-page-1/#comment-520 brent Thu, 29 Nov 2007 16:36:43 +0000 http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/#comment-520 Ha, and here I just figured it was a little arrow cutout. Wow, go science. Ha, and here I just figured it was a little arrow cutout. Wow, go science.

]]> By: Rachel http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/comment-page-1/#comment-518 Rachel Thu, 29 Nov 2007 07:54:13 +0000 http://bestthing.flyingpudding.com/2007/11/29/laser-head-patterns/#comment-518 I think they're <a href="http://hyperphysics.phy-astr.gsu.edu/hbase/phyopt/grating.html" rel="nofollow">diffraction gratings</a>. The line one sounds like the classic diffraction grating pattern: a bunch of parallel slits. This link on <a href="http://www.falstad.com/diffraction/" rel="nofollow">Fresnel diffraction</a> sounds like it may be related to the arrow one. Maybe the little squiggly lines create things that superimpose into the arrow. I can't find anything on the internet to back this up, other than this sketchy <a href="http://www.patentstorm.us/patents/5718496-claims.html" rel="nofollow">patent site</a>. I think they’re diffraction gratings. The line one sounds like the classic diffraction grating pattern: a bunch of parallel slits.

This link on Fresnel diffraction sounds like it may be related to the arrow one. Maybe the little squiggly lines create things that superimpose into the arrow.

I can’t find anything on the internet to back this up, other than this sketchy patent site.

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