Advive about knife edging after cylinder correction

[kitatit]

Hello guys,

Well I've finally got involved with knife edging. This is my first time and I could do with some help before I start drilling mounting holes and gluing optics.

Parts used or planned to be used;
4x Dave's cylinder correction kits
4x Daves's mini mounts
2x lasertack's 7x7mm prisms
4x bounce mirrors
2x Mitsubishi P73
2x Osram PLTB450
1x 800mW Lasever green

Objective is to fit as much of these combined beams through a 5mm round aperture that is approximately 330mm from the diodes aspheric lens.

I know I won't get all of it through but I'll settle for as much as I can.

Beam profile is not super critical.
Beam will terminate at approximately 2.8m.
Ideally the beam diameter will be below 10mm at its 2.8m termination point.

OK. Looking at the configuration in the pics, can you see any problems with the layout?

The main problem I can see is the orientation of the knife edging mount. I had a guess at what width the vertical narrow section of the beam would be at that distance from the aperture. I guessed 3mm so I set it up to strike the right angle prism at 1.5mm in from the edge which you can see on the pic.

The way I have it set up doesn't allow any left right movement of the right angled prism. Can you move the diode mount left right to line the beam up or with this cause to much aberration when the beam moves off axis from the cylinders?

I know experimentation is the best way. I just wanted to check I wasn't totally on the wrong path before I start drilling and gluing.

Any suggestions on how to improve this configuration would be welcome.

Cheers
Kit

*Update* After Marco spotted my goof regarding the second dichro, I modified the layout so that it was oriented properly.



Here is the new layout

[lange5766]

Hello Kit,

Is the orientation of your second dichro wrong?
I mean it is reflecting the red beam back to the first dichro in your cofiguration.

P.S excuse my bad english

Greets : Marco

[kitatit]

Hello Marco,

Nothing wrong with your English I would have written it the same as you.

Ah! Right you are! What a Dumb ass! I'll switch it around. What was I thinking?

Back to the drawing board

Cheers
Kit

[-bart-]

The joys of fitting beams through narrow bores...

Is there any specific reason you want a 5mm round exit aperture, while beam profile is not super critical ?

Cramming a square 3x3 beam through a 5mm tube, will ... can be a bigger challenge than expected.
Losses, surface reflections, edge diffraction

Don't make your life miserable, cut yourself some slack and choose a wider bore (if possible).

[kitatit]

Yeah its a challenge. It's a motor with an 8mm shaft with a 5mm hole through the centre.

The beam will go through the shaft of the motor. If I can get this to work it will help create the effect I'm after.

I can route the beam differently but it will be a compromise.
I want to see if I can get acceptable results doing this before I make that compromise.

[-bart-]

You could focus the beam halfway the shaft making the beam tighter, then re-collimate it at the end, effectively a keplerian telescope.
You will also have the wobble of the shaft to deal with. And since the shaft is suspended on one end, that can be challenge too.

[kitatit]

I was thinking of that but due to having very limited experience and understanding of optics I couldn't think how to execute it.

Have a look at this pic. It should make it a little clearer. I left the motor body off the other images.



Do you think the knife edging arrangement is ok?

Could I position any mounts differently? Especially the knife edge mounts. I think for now I wont drill the holes to mount them to the base.

I'll the holes for all the other components and see how it goes.

It's time for me to roll my sleeves up and get too it and make some swarf. That way I'll have some better questions to ask later.

[slicklasers]

Knife edge them before correction, you can fit 2 into the correction optics without any problems and will give you close to a 5mm beam.

[chad]

Hi Kit,

Just a quick comment. I wouldn't waste your money on a hollow shaft motor and just build a pair of pillow blocks and machine something up and spin it via a little belt and motor. You have the skillz and the tools so make it how you need it.

chad

[kitatit]

Knife edge them before correction, you can fit 2 into the correction optics without any problems and will give you close to a 5mm beam.

Ah Ha! Thanks Slick

That's great to know. Right I'm going to to try that now.

Cheers
Kit