Mitsubishi ML520G71...Red Holy Grail or Flashlight Fail ??

[kitatit]

Thanks Eric, great info. I'm about to buy a few lenses to get a optics learning kit together. This info helps narrow the choice. I'll go larger then. I don't need to handycap myself while I'm learning.

Again, thanks for all the help for us on PL.

Cheers Kit

[catalanjo]

.......... significant component of the overall quality....... the effect is proportional to the FL squared......

Your problem kitatit, is indeed similar to mine,........ how to quantify "significant" in your particular application !
Years of mucking about with fabulous beams from ion lasers, made me very wary of just the number of "mirror reflections" pre-scanners, let alone distortions and stray reflections from prisms and lenses.
However when you start with a pig of an elliptical diode output, this suddenly becomes less "significant", so that the extra flexibility of angled beam paths, long FL lenses and spatial filters, start to become incredibly relevant, and Eric's incessant search for the "optimum" setup, sacrificing different parameters,.... and above all his sharing of the results, becomes as essential as it is impressive, to other would be developers.

The dilemma of tube mounted cyl-lenses IMHO is the difficulty in arranging tilt/twist pre-adjustments to compensate for the slide/rotate advantages (not to mention the pros&cons related to optics cleaning). Ideally, I suppose, it comes down to removable external jigs (expensive) to enable pre-positioning of optical components which could then hopefully be glued onto simple mounts with very accurate re-locating arrangements.
Even then, we encounter glue shrink/creep details which have to be eliminated/resolved somehow.

So if anyone has a re-usable CHEAP zoom/rotate/tilt/pan easy to position releasable clamp for cyl-lenses, please let me know ! (Blutack doesn't count)
OK finished breakfast now !
Cheers

[kitatit]

Hi Cat

"Removable external jigs" YES YES YES! I'm such a short way along my journey of understanding optics but I can see the value of this approach already.

I like precision and tools that help achieve it. Unfortunately I don't have access to a mill and lathe and am away from my home so often It makes it real hard to get these thing made, or even get much hands on time to do anything.

I've been holding myself back from buying a mini mill because I know they will mostly be a disappointment. for the time being, It will be mostly 3D printed plastic, Hacksaw and a file engineering then paying to get parts machined. this is my future dream machine http://www.ronmack.com.au/products/m...ng-centre.aspx
It uses the very user friendly Fagor 8055iA MC CNC Control (Made in Spain) Hopefully I can find a used one in a few years.



It's not quiet what you were talking about but a similar track. see below.

These little fine adjustment screws that Thorlabs makes are 2.5mm x 0.2mm pitch with ball nose end with or with out the knob, 1.5mm hex in the end and in different lengths.
http://www.thorlabs.hk/search/thorse...jusment+screws

You could mount many of the adjustment screws vertically for easy access if you use the screw to drive a ball bearing down which acts on another ball bearing to actuate components sideways. Kind of like how some of the vertical kinematic mirror mounts work.

They are relatively cheap and could be very useful for such alignment purposes. As Thorlabs mention, its almost impossible to tap a 0.2mm pitch hole, so they provide Bronze/brass bush inserts. Some applications would suite a 3D printed nylon jig with the bushes fitted. EOS can print nylon to +- 0.15mm dimensional tolerance. Designed with the right structural rigidity they could be made relatively cheaply. Of course, plastic won't suite all applications and aluminium/brass fixtures would be more suitable.

But I'm getting ahead of myself. First I need understand these fundamental optics principals and see them with my own eyes and hands. When I do, I'll definitely be heading down a path of external jigs and the like.

I made a rough and ready adjuster for Dave's adjustable diode mount for the 2mmFL lens using a two miniature translation stages. It was pretty crude, but worked well enough to show that it had merit and was worth pursuing further. Below is the idea I had to improve it and to be an economical solution. Dave's mount isn't designed with this in mind, so there are a few limitations but it can work.

Kit

[catalanjo]

Nylon with brass inserts sounds fine to me (no rust)................. when can I have one
Maybe a group buy for printed external jigs.
Cheers
PS. Nice link !
PPS. If you turn the base of Dave's mount sideways your allen key won't get in front of the beam!

[planters]

Kitkat,

Even though I have a mill, the majority of my fabrication is one off, small mill/drill work. An inexpensive manual mill equipped with a digital read out (DRO) is plenty for everything I do. The DRO is the secret. It compensates for errors in the mill and makes reproducing parts much faster. Although a CNC would be nice, for non production work the set up would counter a lot of its convenience.

The dilemma of tube mounted cyl-lenses IMHO is the difficulty in arranging tilt/twist pre-adjustments to compensate for the slide/rotate advantages (not to mention the pros&cons related to optics cleaning).

I use the cylinders in tubes and keep the functional axis of the pair parallel to the table. This way the fine centering position in the lens only requires sliding the slightly loosened mount sideways to the axis of the beam. This is easy to do to high accuracy. The height adjustment is not necessary.

I use "custom" one off jigs for gluing small optics like flexmount steering prisms and to allow me to remove an aligned mirror/mount from say the DPSS and to return it without readjustment. This works well. Always label a jig with its purpose for later use.

Once you start playing with your optics kit you may come to find that with moderate FL optics, hand adjustment is more than precise enough. If you use a clean and smooth base plate, and fabricate your components with a nice surface finish you can slide a component that is slightly loose to within a couple of thousandths without difficulty. This method is simple, compact, low cost and extremely stable. Using a jig that you clamp to force the slide in only one axis at a time is a nice trick as well.

After machining, I routinely will take a component and "polish" its surface. If you have ever tried to grind a telescope mirror you will know immediately what I am talking about. On a flat surface, place a new sheet of sandpaper; I like 150 grit. Randomly, slide the component back and forth as well as in a side to side direction and every few strokes rotate the piece in your hand to randomize your hand's pressure bias or stroke bias. After a minute or so repeat this with say 320 grit paper. The surface will become incredibly flat to within waves of error. Using trial fitting, this technique can be used to bring parts that need slip/fit precision that is higher than a hand held micrometer can read.

I tried a version of your micrometer image on a flex-mount by drilling and taping 0-80 holes in the sides of the retaining plate. This tended to lock the diode to a particular rotation when the tiny set screws pressed into the diode's flange plate. This did not work for me and I still struggle with this problem with these short FL lenses. Also, the rotation of the diode in it's mount needs to be done to a demanding accuracy especially if multiple diodes need to be combined. The expansion optics such as the cylinders can only work one a single specific axis. Even though a tube mount will allow you to set that axis to match the diode any additional diode must correspond or the expansion will be askew and that diodes beam will become fatter in the orthogonal axis. A mount that clamped a cylindrical diode holder like the mount DTR recently sent me is a real help.

https://sites.google.com/site/dtrlpf...-mount-modules

What about a precise cut in Dave's mount between the lens and the back, diode support? Now, modify the diode support to a small version of DTR's mount with the addition that the square, outer clamp can slide slightly, horizontally on its base and the front half that supports the lens can slide, slightly vertically? This would require that you start with a somewhat larger version of his mount, but I suggest his design to help visualize the concept.

[catalanjo]

Sounds good !
Have to be a bit careful with respect to thermal transfer capabilities !
Cheers
PS. Reminds me a bit of CDBEAM's adjustable diode mount design ! (don't know whether he actually got round to building one though!)
PPS.Yep ,,,seems he did ...see post 1166 How come Dave doesn't make these

[planters]

PS. Reminds me a bit of CDBEAM's adjustable diode mount design ! (don't know whether he actually got round to building one though!)

I agree. I don't know as well. But, I think if all the effort was directed to making these two adjustments, rotation and X/Y for the lens, that everything after can be done with simple slide and jig and glue with very good results.

[drm916]

PS. Reminds me a bit of CDBEAM's adjustable diode mount design ! (don't know whether he actually got round to building one though!)
PPS.Yep ,,,seems he did ...see post 1166 How come Dave doesn't make these

Yea.. this mounts are pretty cool. I would love to have 8-16 of those mounts.. if they worked. That would make life much easier.

[logsquared]

Hey guys. When the g71 first came out I built some mounts with set screw adjusters. I have found it is much easier to just "tap" the plate that holds the diode in. Do this with the screws just snug.

For these MM builds I find its the rotation that is the most critical adjustment. I have been using the barrel and clamp system with good results.

[drm916]

Hey guys. When the g71 first came out I built some mounts with set screw adjusters. I have found it is much easier to just "tap" the plate that holds the diode in. Do this with the screws just snug.

For these MM builds I find its the rotation that is the most critical adjustment. I have been using the barrel and clamp system with good results.

Whats the barrel and clamp method?