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

[Solarfire]

Well I finalized my decision for optics/selection and placement. Final assembly will follow shortly.
As collimator Dave’s 2mm fl in my own full bridge TECed diode centering adjustable mounts (diode centering is a definite plus) used with the lava lens. First cylinder @ 42mm form the coli/diode mount giving 4mm x 2mm @ the aperture and 14mm @ 11m far field (<1mrad).

Here's some output data after the cylinder correction:
288mW @ 400mA
380mW @ 500mA
465mW @ 600mA
544mW @ 700mA

I’m doing a quad with these on a minimal footprint of 87mm x 73mm, with minimal optics.
4 mounts, 2 mirrors, 1 pbs, 1 WP, 1 set of lava cylinders. Giving a final beam of <4mm x 4mm @ <1mrad.
All beam paths are the same length of 42mm to the first cylinder.

Cheers all!

[badger1666]

lava len question, i have noticed that everyone uses the first lens flat side towards the diode, i tried it that way and never got a good far field beam shape.
does it really matter which way round that first lens goes ? what if any difference should it make ?

thanks

[andythemechanic]

Hi,

it makes a difference du to abberations of the lenses. A simple spherical or cylindrical lens will not focus all incoming rays to one spot, but will blur this spot a bit. Depending on the shape of the lens a ray far from the optical axis can be foused too much or not enough thus hitting the optical axis before or after the fokus. For a diverging lens this effect is opposite to a focusing lens. The strength of the effect depends on hoch much the lens has to bend the rays. At a lens that is hit at the plane size first the second surface has to bend the ray stronger and the effect is increased. In a telescope from a diverging lens and a fokussing lens one can cancel the apperations exactly for a certain focal length ratio (=magnification) and orientation of the lenses.
If in such a telescope one lens is reversed the divergence will increase.
Hope that helps, and in short: yes it matters, :-)

[badger1666]

on my setup if i use the first lava lens flat side towards the diode like everyone else i just a blob as a far beam, if i use curved side towards the
diode i get a nice focused 25mm line at 22m ?? confused , divergence seem the same which ever way round i use the first lens
maybe i will turn it around and try again

[steve-o]

That's the way Dr.Lava's instructions say to do it. Flat side towards the diode. I've had good luck doing it that way .. I don't know what could be the matter Badger.. Are they Lavalenses or a different kind?

[CDBEAM]

OK….Here is my current position. I have NO hard numbers to back this up…yet…but will shortly !!

The debate between using Lava C-Lenses vs. the 6X C-Lens boils down to this…If you are concerned with a smaller near-field geometry to fit on your scanner mirrors…you may want to go with the Lava lenses….you WILL suffer a larger beam divergence. You will also enjoy a more compact footprint for the dual or quad module you will be using…so you will hopefully be able to fit the unit inside your current projector with fewer problems….BUT… Even with the 2mmfL from Dave…I predict the divergence will be greater than a prism corrected 445.

Now…with the 6X lenses…I have seen this set up coupled with the 2mm fL Collimation lenses…and it will deliver a larger near field geometry…but will have less divergence. If you currently have larger scanner mirrors…or are planning on upgrading…or are building a completely new rig, with larger scanner mirrors….you should be good to go. As far as the module footprint using 6X C-lenses… Yes…it WILL Take up more room…but not some huge amount !! Again…it depends on the amount or room you have inside your projector.

OK…all this is just my opinion….based on some observation…until I do a side by side, A/B comparison of the Lava vs. the 6X...with the 2mm fL from Dave. So…I understand that limitation…but….the math sez 6X will deliver less divergence than the 3X Lava lenses…We are getting closer to some solutions on this…just a little more to do.

And finally….the physical mounting of the Lava vs. the 6X…well for me….when using the acrylic mounts…I think the 6X will be somewhat easier to arrive at the optimal position. The Lava lenses will be a little more position sensitive…but once you have the position…lock it down !!

As soon as I have all the glass….I will do an A/B comparison…and post with data and pics ! If someone has already done this…??? SPEAK UP !! If my logic is flawed…That’s OK…I will not be the first time !!!...and….it will be like the attached cartoon !! haha !

BEAM

[steve-o]

Lol, funny Bob, I don't think yer jest flappin your beak tho. Any idea about those 6X lenses, when they may land to earth ? I'd like to git my grubby little mitts on a set of 'em ..

[CDBEAM]

Yea Steve....I too am waiting on the GB.....so....I am a Peep too !! The 6X work...and hammer this Multi-emitter beast into a more desireable geometry....from my perspective....Yikes..." You may fire when ready...Gridley " !!! BEAM

[steve-o]

..Yeah I said peeps but edited it .. , yep hope the GB kicks in soon .. yeah hammer and NAIL IT !!! Can't Wait !!!! It's taking a looooooooooooooooooooooooooooooooooooooooooooooong time .. ;]

[kiyoukan]

okay so doing update now, having a very hard time being one person to get a picture of the beam with calipers in the pic
As its hard to hold the transparent sheet plus calipers and take picture.
Here is my final measurements
0ft 4.03MM
25ft 11.76mm
mRad: 1.0144353475598515


Also i did some testing with flat side vs rounded side with regards to direction.
I got a tiny bit better results with the flat side first.
Still here and alive just very busy