[mura_gadi (Steve)]

Hello,

I have just made my Ronchi tester, but not the stand. I used a LED from a cheap $10 headlamp from Jaycar, the printed Stellafane pdf transparency and fixed it inside a 35mm slide. Worked really well, unbelievable the detail on the blanks surface...

The one thing I found tricky was the alignment, I used a A3 sheet behind the tester to locate the returning beam. Once you have the returning beam it is a lot easier to locate your RoC and to align the tester/blank so the returning beam lands on the correct part of the transparency/Ronchi bands.

What ever the design just make sure you can get your eye in really close to the screen. That is probably the single most important thing to get right.


Steve
Ps. My LED is really bright, I was thinking of using a milk bottle cutout as a diffuser. The board is about 8mm thick, and the bulb is inset to about 3mm away from the screen. I was having trouble with light leaks, the insert was the easiest way for me to cancel them and it got the light source close to the screen.

I found that if you move the stand forward after getting the bands right, you can lose the bands and get a Foucault like test image from the blank as well.

You can get a LED head lamp torch for around $15 posted on ebay, that will get you the battery pack and LED light and a switch if you want it. I had already bought the headlamp for the hands free red light feature and had removed the white bulb. The battery pack was $2 something from jaycar.

Get your eye position as close as possible
Get the light as close as possible to the grid
Get the return beam as close as possible to the source