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

[Solarfire]

is that a tested theory ? to keep the beams heights at the same level

Yes it's tested, the possible offset for doing it the other way around is very small but it’s there. The main reason is that it’s easier and more accurate the other way around, plus the mount design can be much smaller.

[taggalucci]

So where would be the best place to get the wave plate from, is this something Rob could supply?

Try Dave at lasershowparts.com

[dave]

Waveplate GB has just shipped

Along with some other stuff too..

Plenty of spare WP's I think

[tonyaztec]

Plenty of spare WP's I think

Ideal, I know I messaged you through Ebay about some mounts, could you put a waveplate to the side with my name on it and when the mounts are ready I can send you some money.

Thanks Dave.

[CDBEAM]

Some speculation on LD or Collimation Lens adjustability. Well…in a perfect world;

• The collimation lens output plane is in perpendicular relation to the threaded lens barrel holder.
• The lens barrel holder is secured in the LD mount with the output axis parallel to the mount bottom plane.
• The output axis of the laser diode is parallel with the collimation lens output axis.
• The LD position disc remains in a parallel condition independent of X-Y movement within its adjustment range.

So…as we adjust the LD to center its output into the collimation lens, we only move the position disc X-Y. As the adjustment is accomplished and the above bullet points remaining 100% constant we position the LD to minimize farfield output aberrations.

Having obtained an optimal farfield geometry, I would predict that the beam propagation from the collimation lens would be in a complete perpendicular condition to the front fascia of the diode mount and in parallel to the optical platform to which the diode mount in attached. This all happens in a perfect world.

If there exists any deviation from the bullet point conditions (and of course there will be some), then I would prefer the LD position be adjusted to compensate and NOT the collimation lens….so as to keep the beam height at 19.0mm off the optical platform. That is my current logic. Shelf life on this position is approx. 5min!! haha

BEAM

Note: It is amazing the simularity between the Solarfire's pictured mount and mine...and I am impressed with his solution to disc tensioning !!! I may....er...ah..."borrow" that !!! I might also consider using CU as the material for the disc itself to enhance heat removal.

[planters]

Tonyaztec,

The wave plate does not change the apearance of the beam in any way, nor its orientation. But, by rotating the electricfield component it allows the PBS cubes to operate and reflect one, but not the other beam when combining them. This could be and is sometimes accomplished by simply rotating the whole beam physically, but then if the beam is not symmetrical, you'll rotate a l to a _ and they won't stack well

[tonyaztec]

Thanks Planters,

So I had best use the wave plate, I hope Dave will sort one for me

[planters]

Looking to confirm a few assumptions.

If a single diode after a 2mm lens then 6X beam expansion to 2mm by 4mm has a 14' far field spot of 8.5mm x 8.5mm then do a carefully knife edged pair through the same optics produce a 4mm by 4mm beam with the same far field spot? Or is there some overlap in the near field?

[CDBEAM]

Eric....due to the small vertical wing aberrations that present at the farfield, and in the absence of a beam analyzer ( failed to receive Lascad for Christmas as requested...haha)...my analysis is basic !! The farfield geometry is more like a squarish oval....or a round cornered almost square...and the beam is slightly wider than tall....but the slight vertical wing aberrations make the geometry look more like rounded square and not like a bar . I have knife edged the 445 and not the G71 yet, but I would imagine that there will be overlap..both at the nearfield(slight)..and more overlap at the farfield ...as there is with the 445. Others have knife edged the G71....what do you see ???? BEAM

[planters]

Is there overlap with the 445? I believe you, but using prisms with these spaced at most 100mm from the diodes all I have seen is an expansion of the stripes. The lower divergence seems to explain this. Maybe if allowed to continue to broaden for say as much as 1,000mm the two 445 beams will then be almost indistinguishable from a single beam. With the G 71, the initial 0.5mm stripe is diverging at nearly 10 mrad and at 60mm has more than doubled in width and if allowed to to continue to expand for say another 60mm it will have tripled and so on. The knife spaces DO NOT DIVERGE and it would seem that the near-field dimensions would allow two 4mm x4mm beams to overlay almost perfectly creating a near field beam only aprox. 4.5mm wide. This would allow for half the divergence of a 2mmx4mm beam and still allow the two beams to fit on a 5mm scanner. Not so?