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

[andyf97]

I probably should do the ultimate power tests of the 9mm 445 and the P73. I suspect the numbers at -30C will make a few people giddy. But I don't plan to kill them.

Will be great to see what happens at -30, I can't go that low. I am sure we would have a lot of fun if living in the same street too.

[steve-o]

I have one setup ready to be killed, just no time to give it a controlled condition firing squad yet )

Ahhhh!!.. Please think about this before you do it Andy .. Don't do it !!!! Just think about it first. PLEEEZE !!!!

[Stoney3K]

I probably should do the ultimate power tests of the 9mm 445 and the P73. I suspect the numbers at -30C will make a few people giddy. But I don't plan to kill them.

Are you sure your power meter can handle that abuse?

A single 9mm 445 at -30 would start to qualify as a directed energy weapon!

That's what I too thought at first, but the reason spatial filters have a long legacy of micro dimensions is that they have traditionally been used with gas lasers with relatively small diameter beams and the filtering effectiveness is related to the ratio of the input beam diameter to the diameter of the focal spot. Filtering at the 99.9% level is typical. The process is exciting because the effect is much more elegant than simply masking the peripheral energy. Much of the high frequency (read Fourier) noise such as dust ripples, lens scatter and multi-mode stripes are also removed and so the filter should be placed as far along in the beam line as is practical. This makes a lot of post filtering beam manipulation less attractive. However, that being said I agree that the demanding precision of a typical filter is unnecessary. If I can successfully remove 90% of the far field noise then I'm way ahead of the state of the art and this is easy. It is so easy that I can hold the aperture for a short time FREE HAND and the result is impressive.

IMO, the practicality of having a big, less effective spatial filter with some degree of control seriously outweighs the benefits of a micro-scale filter which produces a 99,9% pure beam.

Remember, we're into entertainment purposes here, not scientific applications. If we create a beam that is round, bright, and sharp enough to draw pretty graphics, the audience (and therefore, the customer) will be satisfied.

But for the sheer knowledge and advancement of science, by all means, hack away.

[planters]

IMO, the practicality of having a big, less effective spatial filter with some degree of control seriously outweighs the benefits of a micro-scale filter which produces a 99,9% pure beam.

If we create a beam that is round, bright, and sharp enough to draw pretty graphics, the audience (and therefore, the customer) will be satisfied.

But for the sheer knowledge and advancement of science, by all means, hack away.

I think I agree with you. I think I do. Regarding micro-scale, yes that's right out. Too hard and not worth the effort. I'm not even going start down that road. A simple moderate performance filter however, is easy construct and increases the contrast substantially. I think this will improve graphics as well as beam shows.

Remember, we're into entertainment purposes here, not scientific applications.

I know what you mean. This is not just for enlightenment, these lasers/optics are mostly for display, but you know I am doing here right? It might be possible to go out and buy a Sparks system or spend $100,000 for an incredible 15W OPSL. But, by picking out some approaches used in various parts of the scientific community and applying them to these far less expensive systems there can be a large benefit vs cost

[f150trk21]

Ok, got my adj. mount and 2mm lens from Dave. I have it set up so the beam comes out of the lens like this " l " then hits the cyl. Corrective lenses, is that right? I thought it was supposed to be like this _ .

Thanks

[planters]

You have it right. It comes out like a vertical stripe (that is quickly diverging and within less than a meter will become a horizontal stripe). The lens pair will expand the vertical to a horizontal stripe much sooner and in doing so will reduce the far field divergence.

[f150trk21]

Still working on spatial filtering. This is probably going to work pretty well.

However, in the mean time I have uncovered another wrinkle, maybe a good one. Aligning the diode axis well with the cylinder optics is very difficult. The diode mount I am using from LSP allows the diode to be positioned so that it is centered on the collimator. This works well and produces a more symmetrical central far field spot, but the rotation of the diode in its countersink is pretty much hit or miss (mostly miss). With the rectangular correction optics it is easiest to mount them with the expansion axis strictly parallel with the floor. If the diode is rotated even a few degrees from level the effect on the far field spot is to noticeably increase the vertical dimension of the spot. To visualize what I mean imagine if you compressed \ horizontally vs _ The problem can't be corrected by adjusting the lenses in rotation unless all the diodes were "off" by exactly the same amount and in the same direction.

The best solution is to set the diodes as perfectly parallel as possible. I am considering using a VERY small set screw in the side of the back retention plate, so that once the diode has been installed as close to good as possible then the set screw is tightened and the final tweak is performed along with the X/Y shifting operation.

The reason I think this might be good is that when the lenses are optimized for the rotation of a single diode and the near field spot is 2mm x 4mm the spot I get at 13M is 12mm x 25 mm. This is 1/2 as high as I was expecting.

Yeah Im having a hell of a time trying to level the beam, need an easier solution.

[planters]

Sorry, I should have updated this post. The set screw idea works very well. In the side of the back retention plate, I drilled and tapped a 0-80 hole for a 1/8 inch long pointed set screw (yes,they are incredibly small) which is the smallest I could get from Mc Master Carr as a stock item (god I love them and I bet they love me too). Start by using the slightly loosened, retention screws and by holding the diode's leads between your fingers and rotate the diverging collimated.but uncorrected beam projected onto a screen about 1 meter in front of the diode. Push down gently as you do this to insure that the retention plate is not free to skew, but held square by the retention screws (the CNC machining of these parts is quite good and symmetrical). With your free hand tighten the set screw. Now, SLIGHTLY tighten the retention screws so that with a series of small taps you can shift as well as fine tune the rotation. This last step should be done in the far field ie out 5-6M and reflected back to a screen conveniently placed in your field of vision (10-12M total). After you have achieved maximal symmetry in the focused spot;no wedge and symmetrical multi-mode stripes then replace the 1M screen and mark the location of the spot vertically as well as horizontally. Using this spot for subsequent diodes will simplify co-alignment of multiple diode modules. Do you have the facilities to drill and tap at this scale? If not let me know.

[steve-o]

Ok, who's having the best luck with NF and FF specs with the G71s or P73s? I've read claims of 3-5 mm beam ap sizes and <1mRad divergence . I dunno. Anybody wanna share their "secret" formulas? I'm not having that great of luck these days with these red projects .. I don't know what happened .. :/

[badger1666]

hey steve-o i thought you had all this red stuff licked ?? what happened man!
i have had a 3 banger p71 for a while now 1.6w of fun .@1.1mrad on lava lens sets and 2mmfl lens
just about to start a four banger 4w p73 towards converting my pj into a 10w rgb

cant say that my beams are that great , but most are to fussy about them, and you really dont notice any inperfections when doing beam shows