solarGain, new SHG

[solarGain]

I am still at the building and fine tuning stage of my SHG, a la thesmiths.

So this is my first image. Camera - 1st focus, Collimator 2nd with Telescope 3rd focus. It is taken with the aid of a 50x50mm Holographic DG. And I am assuming at the1st Order. To my eye the top and the bottom is out of focus but the middle section is firmly in best focus. I’ve believe that I have gained control over all aspects of FOCUS. I’ve even looked at the ‘image’ in Mac Preview and can ‘bloat’ the image as well as literally/ clearly see the length (I assume) of the 12mm x 9 micron slit (thesmiths) . In this mode the slit tapers off at top and bottom to a very fine tapering points. All actions are now repeatable.

So my question is this, is the middle part sharp in the image (Genika sw) and the rest is bloating or am I still some distance from sharpness over the full length of the image as shown? I know that I only needs a fraction of this image to scan the full sun. It is sticky and v.humid, so thats for another weekend now.
John

[thesmiths]

Hi John, one minor point: you should rotate the camera so that the spectral line is along the long axis of the camera sensor. This will help later on when you use a narrow ROI. The camera will read much faster if the line is orientated parallel to the long edge.

It's not clear from you description if your collimator is actually collimated. That is the most common problem when you first set things up.

[solarGain]

I was hoping that either way this line was in focus. The collimator is the 2nd piece that has been focused, possibly poorly. The lighting used was a fluorescent lamp so not a strong lighting force. I also thought that the horizontal scan would be right but the 'bloating' at both ends I didn't want to see!

[thesmiths]

The collimator is the 2nd piece that has been focused

How was the camera lens focused? It should be focused to infinity first in order to properly collimate the collimator.

[solarGain]

Ok, I have too many variables, things are not locked down. I believe I can now lock down the two Pentax Takumar lenses.
So this is the horizontal scan line shown on Genika. The line is at best focus without any sharpening involved.
One variable is that I do not have fine control of the horizontal line without wring both hands around the eyepiece end of the Tak 60 with all of its lack inter-operative components etc. So I need to get a small nut/screw glued the the flat edge of the cell that holds the slit so as to carefully rotate the slit to horizontal.
I think then ready for shooting.

[solarGain]

IMG_1168.jpg (312.1 KiB) Viewed 2168 times

And now for the image , duh!