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Ronchi tester

Started by p3x249, 08/26/2002 03:28AM
Posted 08/26/2002 03:28AM Opening Post
Hi all,
What is the best easiest way to make a simple Ronchi tester? I have the 80,100,150 lines. Radio Shack, Walmart or around the house stuff please. ~~Sonya~~
Posted 08/26/2002 10:28AM #1
Hi Sonya,

The easiest way is to simply have a light source, the ronchi grating and something to hold them. Here is what I did, and I can upload a file when I get home after I have lunch. Drill a hole in a small piece of 3/4" or 1/2" plywood. Since I used a "Mini Mag" light that turns on by unscrewing the front I made the hole on the wood such that it would firmly hold the front of the light and I can just turn the back of the light to turn it off and on. Next drill a hole 3/4" to 1" just above that. Say 1/4" or so above. Put simple ronchi grating in front of them and mount the whole thing on something so you can position it properly.

The pictures will help...

Posted 08/26/2002 11:40AM #2

Peter Smith has a nice page on Ronchi Rigs and also interpereting test results.

Posted 08/26/2002 01:10PM #3
Ok here is a picture, this is a very basic tester that I just attach to my camera tripod when needed. The only improvements I would make are:

1. A viewing hole that the grating is taped over so that the grating is held straight.

2. one of the larger AA cell mag lites with the new fiber optic neck accessory on it. Or one of the new white led camping mini flashlights that Target carries for ~$6.00.

This type of tester is ok for finding the initial shape and detecting surface errors, but a bit more complex tester on a measurable moving stage is needed for final figuring.

Attached Image:

AstroJack's attachment for post 62367