Another project red?

[MechEng3]

OK lets see some pix. I am begining to lock down the layout for the diode holders tonight. Is this going to be a share all thing or are there any others planning to build a 12 diode unit? I have had good results using a very small shorting pin or just a touch of solder on the 2 active pins. Try not to rotate the one pin...it will most certainly break the bonding wire to the die. On my leads from the diode I always have a shorting wire attached and is clipped and heat shrink covered after all conections. This bleeds off the stored voltage in the driver after setting it up. This also allows furure diode replacement with the ability to shunt the transplant. CYA ...point blank. I have finished another 1/2 watt red for now...time to start on the big guy. I will have access to a good mill next week for a few hours....time to nail down the locations of all holes...
On a tangent...the 12x 405 BR diodes... are they very expensive? Who has sleds for sale ? I would like to build a quad using these....

[logsquared]

Here are some pics. The one shows the two different mirror mounts i made. The one with the "rocker" was meant to have a 4-40 steel screw as the pivot point. The spring tension was to come from the 4-40 pivot screw. There is a 4-40 set screw on the tail end that pushes against the base. Two problems with this design. 1. its a PITA to machine with any tolerance. 2. i think the steel pivot screw will gain torque when the side pusher is used. i think this may lead to creep over time. The mount with the flat bottom i think is what will work best. Instead of a steel screw i use a nylon 6-32 screw. Now the tension comes from elongation of the nylon screw not bending. Also, the nylon screw doesn't turn with the side pusher reducing torque on the pivot.

In the second pic the 8X base can be seen. (not all the mirror or diode mounts are installed). There are two small issues i have seen with this mock-up. 1. The side pusher is only "one way" it is kinda like an old typewriter. If you go too far you have to back the screw off and manually pull it back over. This could be fixed with a "puller" screw next to the pusher. I don't think i will need it because after it's set i will glue the mirror mounts and take those side pushers out. ( we will see how that goes with 8 diodes though!) 2. My mirrors didn't glue on as straight as i thought i could get. To fix this i will machine the mounts to angle the mirror slightly up. This way the beams will all start out pointing higher than center allowing adjustment for mirror misalignment from glueing. Currently it can only be adjusted below center. If the back mirrors get glued slightly pointing down (some did) then they get clipped excessively by the front row.
IMG_1279 copy.jpgIMG_1283 copy.jpg
Pretty simple huh?

[MechEng3]

This is a V2 of a proto that has proven to work and has good stability and compactness. This has undergone many hours of design and theory...I would be interested to get a file out to someone with a CNC mill.....these have all the goodness I will need for alignment....any jeering from the participants on a GB for a pack of these to be made up? Can be cut to lengths needed...shaded area is to be a drilled hole for rotational movement and tightening. Mirrored side faces the hole in the top of the device...keeping things centered and simple. Simple but very effective in this case for me. Material is T-6061 .375 round stock...cheap and readily available. I think it is a great item worthy of some sort of patent....maybe...my head is filled with ideas to take this chore on.

[logsquared]

NICE! I think simple is the way to go for this type of build.

The #2-56 will give you your Y axis adjustment. How will you make the X axis adjustment?

This seems like a variant of the square flexure mounts. I have never used the square type i have seen sold on this forum. Anyone know what the long term stability is? I steered away from the flexure mounts on my design because i worried about drift from the relaxation of the stress in the metal. I am not saying this would happen. It was a concern though. In my first designs i really wanted to have adjust-ability for correction if the beams started to walk. Somewhere along the line i came up with the set and glue idea. I am hopeful with temp. stabilization long term stability should be fine.

[logsquared]

I do remember the axicon thread... too bad it's been long gone and forgotten



--DDL

I must have missed this.

The axicon thread can live. Check this out: http://www.photonlexicon.com/forums/...le-beam/page12

[Laserman532]

This is a V2 of a proto that has proven to work and has good stability and compactness. This has undergone many hours of design and theory...I would be interested to get a file out to someone with a CNC mill.....these have all the goodness I will need for alignment....any jeering from the participants on a GB for a pack of these to be made up? Can be cut to lengths needed...shaded area is to be a drilled hole for rotational movement and tightening. Mirrored side faces the hole in the top of the device...keeping things centered and simple. Simple but very effective in this case for me. Material is T-6061 .375 round stock...cheap and readily available. I think it is a great item worthy of some sort of patent....maybe...my head is filled with ideas to take this chore on.

it is possible that I just dont see it...but how is vertical adjustment achieved (except other than precise machining). The issues (as I understand it) was the vertical height adjustment.

As I also pointed out to buffo in a PM...any design like this would also require PRECISE cut mirrors. (not to mention a standard thickness.

[buffo]

it is possible that I just dont see it...but how is vertical adjustment achieved (except other than precise machining). The issues (as I understand it) was the vertical height adjustment

Hi Pat;

Are you talking about Mo's design or Mike's design? With Mike's, I believe the vertical adjustment would have to be via shims, but Mo's design incorporates a vertical adjustment screw.

any design like this would also require PRECISE cut mirrors. (not to mention a standard thickness.

I completely agree. And in fact, my reply to you in that PM was that you already sell precision-cut mirrors that are all the same thickness (and are also quite affordable). So that's a problem that is already solved.

The key (in my opinion) is having the shelf on the mounts so that the top edge of the mirror is always straight and they're all mounted at the same initial height. Then you can shim the mounts to get the extra height you need. (Or, in the case of Mo's design, use the height adjustment screw.)

Adam

[logsquared]

it is possible that I just dont see it...but how is vertical adjustment achieved (except other than precise machining). The issues (as I understand it) was the vertical height adjustment.

As I also pointed out to buffo in a PM...any design like this would also require PRECISE cut mirrors. (not to mention a standard thickness.

I think the height could be adjusted with MechEng3 post style mount only by machining or shimming if needed. Probably a simple washer could be used as a shim. I don't see how the thickness of the mirror would matter much. I can't see from the drawing how adjustment in the X axis would be made.

On my combiner i use a jig to assure the mirror is the correct height and centered properly. My base plate is machined on a mill to accurately set the row widths at the correct place.

[Laserman532]

Hi Pat;

Are you talking about Mo's design or Mike's design? With Mike's, I believe the vertical adjustment would have to be via shims, but Mo's design incorporates a vertical adjustment screw.

I completely agree. And in fact, my reply to you in that PM was that you already sell precision-cut mirrors that are all the same thickness (and are also quite affordable). So that's a problem that is already solved.

The key (in my opinion) is having the shelf on the mounts so that the top edge of the mirror is always straight and they're all mounted at the same initial height. Then you can shim the mounts to get the extra height you need. (Or, in the case of Mo's design, use the height adjustment screw.)

Adam

About the adjustable mounts:

Shims - how many and what thickness would be supplied / necessary? With mikes design shims can be as simple as washers with a 4-40 hole in them (however washers will add instability and perpendiculariosity (leaning tower of pisa) issues.

Mirrors- I have found that most folks dont like aluminum coated mirrors (the ones I sell) (true they roll off quickly at 405 and are only around 90 something R at other wavelengths). (my ROI clearly shows that...DOH!)

Moes concept could be expanded upon. When discussing height translation, one must first determine "range of height" adjustment necessary. It is a very broad discussion with many variables.

The main problem has always been standardization (hence ilda). I make everything .75" above a 1/4" thick baseplate...making all beams 1" above any surface. The standardization thing was driving me crazy so I made my own standard (my euro friends would have preferred me to go metric )
About the concept:

In my first "response post (see my post #4)" I actually was not thinking of a bunch of diodes being combined with a bunch of adjustable mounts, I was actually envisioning a "disc" with diodes pressed in diode to diode (very much like a multi LED flashlight) which is why i asked if those were the beams or the diodes or the lenses (or something to that effect) Where I was derailed was with the first drawing thinking that it was a diode bank and not a beam pattern on the wall (artist rendition of course). Now my mind wonders to the question "are those aixiz modules nested" and if so...the aixiz's modules are far greater diameter than the beams exiting the lens's which creates one hell of a collimation problem.

anyway...would like to see what mike envisions as the mechanical setup not just what he would like the "spots" to look like on the wall...(no offense to mike here either)

mike do you have an artist rendition of what the mechanical layout of the array would look like?

[MechEng3]

Here ....maybe this will help...I am not spending time drawing when I can build. Considering the 3 engineers that doodled on napkins at a diner and designed the Studebaker Avanti in 1962...and went into production from there 2 weeks later... this laser will be made soon by me. I will show pix along as it comes together. Really want to build a quad with 4 of the BDR-205 diodes...reported to go up to 625mw each and live on a heatsink...I would like to see 2 watts from it though...Hmmm....2 watts of 405nm for less than $1K. Maybe I am not showing enough info on this platform setup..... No CAD drawings...just notes and sketches on my pocket notepad. By the time I draw all this out I can have one machined on a manual mill. My lathe in the workshed will do the mirror posts... I will scan the parts and then have a set of drawings on the server as soon as I can. Then all can just download and carve away...my reamer came in today for the Aixiz diode holders...now I can make a nice fit there. The ally diode blocks will be mounted onto a .5" T-6 block or copper with a TEC attached underneath it. This will be assembled onto the .25" baseplate of the laser. Comon guys...you have built this same thing but on a smaller scale. Just a few tweaks here and there. The big deal that everyone has missed is that the mirror holder has the dichro in the CL of the post. If you have aligned a multiple diode laser, you know that this is a big deal. Precision at the diode mount and drilling locations are utmost with this design. If the diode is in the right place...everything else will fall into place from there. I do use a bit of the ability to steer the beam a bit with the lens movement on the diode itself. Then all is locked down. Hope this helps and not to come off as a smart a$$. Just wanted to get people more involved with building and design. The other big thing is the fill factor and the beam placement at the cube.

[buffo]

Shims - how many and what thickness would be supplied / necessary?

Excellent question! It will depend largely on the diode and lens selected for the build. I think Mike is leaning towards the long open can reds, but as to which lens he ends up using - that's still up in the air. There is a trade-off between cheap lenses at the start (which yield fatter beams that are easier to overlap, at the cost of a larger overall beam), verses expensive ones that yield superior beam quality but add significant costs (up to 3X the cost of the diodes) and also make the "knife-edge" alignment absolutely crucial...

If I were attempting this project myself, I'd probably invest in a set of motor mount shims. (The ones they use to align a large industrial motor to a pump, for example.) They come in standard widths - like .1 mm, .2 mm, .5 mm, 1 mm, 2 mm, 5mm, etc... You just stack up enough of the ones you need. They are "U" shaped and usually run around 2 inches square. You could even cut them to size using a dremel tool, so one shim could be cut down and used for several mounts...

With mikes design shims can be as simple as washers with a 4-40 hole in them (however washers will add instability and perpendiculariosity (leaning tower of pisa) issues.

I actually tried using large fender washers (to get around the "leaning tower of pisa" problem) on a little project (not laser-related) I was working on about a year ago. And what I discovered was that the thickness of your average fender washer varies quite a bit from one washer to the next. So you would need to do a lot of measuring to find one that was the exact size you needed. That's why I think a standard shim set would be the ticket. (Though, admittedly, I have no idea how much they cost.)

Mirrors- I have found that most folks dont like aluminum coated mirrors (the ones I sell) (true they roll off quickly at 405 and are only around 90 something R at other wavelengths).

Well, I wouldn't be too worried about the 405 nm wavelength, but the 10% loss per mirror is a good point that I had forgotten about. That would be an issue for most builders, I think.

Still, if someone was willing to purchase, oh, say, a 1 ft square sheet of high-reflectivity mirror and have you cut it up into ~ 1/2 inch squares, surely there would be a way for you to make a profit on the cutting while still keeping the overall cost of the mirrors affordable, yes? Might have to resort to some sort of group-buy on the project, but I think it's doable. (Of course, all of this is predicated upon a completed design...)

When discussing height translation, one must first determine "range of height" adjustment necessary. It is a very broad discussion with many variables.

I think the range of height adjustment can be defined rather easily. Assume that the maximum number of diodes anyone will want to stack in the vertical direction is 4. That would yield a theoretical maximum of a 4x4 array, which is 16 beams, which when doubled through a PBS would be 32 beams, and that is 33% more than the largest home-built red (Phritzler's 24-diode monster) we've seen to date. Now assume that the worst beam diameter you'd ever get from a single diode is ~ 3 mm. So your maximum height adjustment would be 3 mm times 4 beams, or 12 mm. Or about a half inch, give or take. That will get you close enough for 99% of the projects people have in mind... (As you said, in the absence of an industry-standard specification, make up your own spec!)

I actually was not thinking of a bunch of diodes being combined with a bunch of adjustable mounts, I was actually envisioning a "disc" with diodes pressed in diode to diode (very much like a multi LED flashlight) which is why i asked if those were the beams or the diodes or the lenses

Ahhhh... That makes a lot more sense now that you explain it that way. I never even considered looking at it that way. If you did mount the diodes like that, you're right - you'd have a lot of "dead space" between the beams...

would like to see what mike envisions as the mechanical setup not just what he would like the "spots" to look like on the wall.

This is going to be complicated, without a doubt. I expect it will look a lot like Phritzler's rig, just with fewer diodes. Also, the final output beam height is probably going to end up being some non-standard value, but for gobs of red, I think people can live with that.

I've sketched a few simple layouts on paper, but never anything with as many diodes as Mike is contemplating. Still, once you have the basic layout, it will scale more or less evenly up to more diodes, so long as you remember that the height stacking needs to be done from low to high as you move further away from the cube...

Adam

[MechEng3]

Here is a quicky...close to what I am doing...same tought process....the original drawing depicts the output view of the beams from the cube. Beam heigth around or right on 1" above base.

[logsquared]

I still don't see how you will adjust the X axis?

[Laserman532]

Here is a quicky...close to what I am doing...same tought process....the original drawing depicts the output view of the beams from the cube. Beam heigth around or right on 1" above base.

thank you, that is the language i can understand i look forward to the real deal!

[shrad]

you could compact your design by placing the two diode rows back to back, using a mirror, and placing the boards over the diode rows using spacer screws

[MechEng3]

OK some progress has been made...back to back rows...note the arrangement of diodes...should have together in a couple of days here and there. Posting pix as I make headway...working weekend. Always when I have a good project in the works.

[logsquared]

How much offset is between the high and low diodes? Also, i was thinking a 2-56 screw may not give enough resolution for alignment at 100 feet or so. I use 4-40 on my mounts and it is just enough to allow accurate alignment at 100-125 feet.

[logsquared]

Got the rest of my diodes in. This alignment method seems to work pretty good so far. Real easy to align at 30 feet (the longest distance i have inside right now). With a little more adjusting i can get the two rows closer together for sure. Outputting 990mw @ 2.56Amps (all diodes in parallel). A little lower than predicted. Each diode is doing about 190 mW. 8 X .19 = 1.52W. 1.52W X .9 (mirror loss) X .82 (knife edge loss as measured before) = 1.12W. not too bad though. Any suggestions or input would be appreciated before i start my three row 18 diode combiner.IMG_1293..JPGIMG_1288..JPG

[hobbybob]

Nice report, very interesting to follow.
Is there a way to close the "gap" between the upper en lower row dots ?
From the 1st photo it's a bit hard to see the beampaths.
Do the mirrormounts just rotate on that nylon screw, driving by the long screw ?
(Just to see if i understand it right ?

Keep up the good work ! Nice. Very nice.

[mccarrot]

Very nice setup you have there, pleae keep in mind the centre of a beam contains the most power.

At some beams it looks like you only use the left half of the beam. It does not matter if you cut the sides of the beam because there is little power on the sides, but focus on the centre of the beam.

[logsquared]

Nice report, very interesting to follow.
Is there a way to close the "gap" between the upper en lower row dots ?
From the 1st photo it's a bit hard to see the beampaths.
Do the mirrormounts just rotate on that nylon screw, driving by the long screw ?
(Just to see if i understand it right ?

Keep up the good work ! Nice. Very nice.

After some more adjusting it became obvious to me that the gap between the rows is from crappy mirrors. The edges have a slight chamfer. It is this edge that is shading the top row.

You are correct. The mirror mounts rotate on the nylon screw. The long screw pushes the mount about the nylon screw. Also, there is a set screw in the rear of the mount that moves it up and down.

I just set up a mirror on the far wall of my shop to bounce the beams back. This gives me about 60' of throw. It also makes it easier to see the beams while adjusting.

At 60' the 4-40 screws in the rear of the mount are more than adequate to control the beams positions. The longer "pusher" screw is a little more difficult due to play in the threads. They are cheap hardware store 4-40 screws. Hopefully i can make it to the supply house to get some better machine screws this week. Overall the whole mount positions good with minimum crosstalk.

I am going to let is sit for a day or two and set how bad the beams walk off. If things stay in allignment i will find somewhere with a longer area and set the beams to overlap at hopefully 150 feet. Then i will epoxy them in place. After that i plan on temperature testing to see how far the beam walk between say 30 - 100 deg F. If i can get away from TEC i will be jumping for joy.

[logsquared]

Very nice setup you have there, pleae keep in mind the centre of a beam contains the most power.

At some beams it looks like you only use the left half of the beam. It does not matter if you cut the sides of the beam because there is little power on the sides, but focus on the centre of the beam.

Thanks.

This was just the very first alignment. I have since been able to center the beams much better. Curiously, the total power only increased very little.

If you look at the picture of the expanded beams lines can be seen between the spots. These lines and the area between the top and bottom rows form a "window". This window is set by the machining of the whole unit and the edge quality of the mirrors. I can move the beam side to side in the window but only slightly up and down. Also, i can't adjust the width of the window unless i change the machining. The outside "corner" spots don't pass by other mirrors. So, they appear to have a semi-round shape. But as you said, there is no real power there.

[MechEng3]

Here are a couple of pix....Mo please PM me.,, I need an e-mail to send you a blueprint. It is burning in ..... should have it done soon.

[allthatwhichis]

...............


I got a box I can put that in...

[MechEng3]

Well I have a crystal set ordered...diode has been here. Should be able to cobble up 650mw of 532nm to go with it. I was planning to put them both in a box......I was hoping to get hold of a couple of BDR-205 diodes sometime...stable at 500mw each....then RGV in a big way....may not happen though...cash is getting tight with hopefully the last of doctor visits over soon. I may BST the 3/4 watt laser...not sure yet...