how short must the exposure be to ...

holorefugee · Post by **holorefugee** » Sat Sep 08, 2012 8:42 pm

That brings up my favorite Dinesh quote of all time:

Dinesh · Post by **Dinesh** » Sun Sep 09, 2012 8:23 am

Well, when you're examining or trying to analyse a physical situation, the most important thing is to get a physical intuition of the various phenomena playing out from a physical point of view; a "sense" of the thing, as it were. I think in pictures, so I "see" the phenomenon playing out almost like a movie. Once you get that physical insight, the mathematics fleshes the details and acts like a scaffolding to show the progression or evolution of events. But, as I said, the most important thing is to get this physical insight. If the physical insight is sufficient to model the phenomena up to the level of interest, then you don't need the mathematics. In this case, the mathematics simply gets in the way. Effectively, you have too much detail and the actual physics (or engineering) gets obfuscated. Also, the physics must drive the mathematics, not the other way around (all too common!). What we're doing is trying to understand a physical process, and mathematics is but one tool. The laws of nature is the framework and the mathematics is the mortar. If a basic framework is enough, you don't need any mortar. If all you need is a tent for a weekend camping trip, you don't need to order a lot of cement and mortar to build a brick wall in case of hurricanes! There's nothing "smart" about showing off tons of mortar to your fellow campers to show how much foresight you apparently have to take account of every possible turn of events.

In this case, the laser light hits the skin, the laser light bounces off the skin, the laser light from various different parts of the skin hits a specific part of the plate, the various light beams from the various parts of the skin form a greyscale "blotch" on the film. Look at a point near to the blotch, there should be another blotch. This other blotch is a little darker, or maybe a little lighter. So, OK, keep both those blotches still awhile, I'm trying to take a photo of them. Say "Cheese", blothces. Now dammit, the blotches moved! Why? Well, because the subject moved. This subject is antsy, it can't keep still. Giving it a lollipop ain't gonna help! So, what are my limitations? What's causing it to move? Well, it's living skin. How can I model living skin to get a better idea? One way is to think of it as the membrane on a drum head. But, underneath this membrane is a reservoir of liquid attached to a piston. The piston is constantly being drawn backwards and forwards. As the liquid surges and falls back under the membrane, the membrane oscillates. Does this matter? Will a piece of mathematics allow me to predict the rate at which it rises and falls. But, maybe it's not necessary. If I can find a faster camera, or maybe light it better I can overcome my problem. Well, I can find a faster camera, a pulse laser! So, do I need to analyse further? No!

Arturo · Post by **Arturo** » Thu Feb 21, 2013 5:18 am

Ed Wesly wrote:I have dusted off and posted the paper on scanned Holography and Its Application on my web site, along with images done in this manner.

http://nlutie.com/ewesly/PreambleQuScan.html

It's hard to believe that we did this over 20 years ago!

This is nice, Ed... Whatever happened with this? Any google search for "scanned holography" yields results on 3d microscopy reconstruction... Were there any follow-up papers to this?