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Laser projector optics

likevvii

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Hello,
I am researching laser projector with phosphor wheels. They usually come with diode arrays. I know some members here have taken some apart to learn about them, or to harvest the diodes.

I need some advice on what type of optics they use to focus the array onto the phosphor wheel.
I am wondering how they do it. A special custom multi lens or something? Or maybe just a convex lens to aim them at the general direction of the phosphor wheel?
What spot size do they focus down to for the array?

Any recommendations on a projector that has a high powered array that I can purchase to disassemble to study how it works?
 



hakzaw1

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Dozens of member have harvested hundreds of blue 445 diodes- the 24 5.6 mm diodes are 'joined' by mirror edge knifing --
that hits a wheel with a clear slot that allows enough 445 for the blue. The green comes from the wheel coating--the red comes from a bright LED- these are joined to make white in an optic train
Have you SEARCHED? many threads and lots of posts with MANY pics and descriptions.

The above pertains to the first Kasio PJs (do NOT spell that correctly in the open forum PLEEZE)--later Kasios switched to 9 mm and afaik ALL BenQs have 9mm also. There is one 'trick' to open the first Kasios- all screws are easy to find and remove except ONE. it is somewhat hidden below some other parts and near the center-- a part or two needs to be removed to gain access to this last screw.

The array can be taken out whole --wires removed and the array can be reconnected and the entire array can be 'lit' but only for a few seconds as the cooling fans will not be doing their job-- I shine the 24 beams on the ceiling to look for any that seem dimmer or not working== the array can be partially removed--the wires are short-- you can only tilt the array a little.

by all means use ESD precautions at ALL times.

Removing the 24 diodes from the block has also been posted here. It does NOT have to be difficult PM me for more info (that you were not able to find by SEARCHING.)
there are lots of nice optics including 2 dichros. and FS mirror.

Which Kasio are you working with?--very first had the least powerful 445s @ about one W--
its the A-130 --

search
then
search some more
good luck===hak
 

likevvii

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Thanks for your help.

I am very new to projectors and am not familiar with the terminologies used for them at the moment. I did some searching with keywords such as array, projector, phosphor wheel. But I cant seem to find what I am looking for.

Most of what I find are knife edge arrays from thorlabs with like 4~8 diodes, They are large and expensive. Laser projectors have 16~24 diodes and are also compact. I have yet to see a picture of a compact one that the projectors use.

Not only does the beams need to overlap at one spot, they also need to be focused. Is there like some kind of aspheric lens for each diode before they get knife edged?

_
I am currently using the nubm31t and am able to focus down to about 3x2mm spot size simply with a plano convex lens.
Will using laser projector optics produce a smaller spot size? The key is the spot size to know what kind of power density I can achieve.
 

Light superglue

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A simple plano convex lens must be the best thing to focus many well collimated parallel beams if you want the sharpest spot. From practice standpoint an aspherical plano convex lens should be better doing this (to avoid aberration!) than spherical but usualy no one cares about aberration and I do not recall hearing about such special lenses.

The best way to understand what optics is there in projectors is to buy one "dead for parts" and look yourself. This is how I did, old a130/m130 from the maker Hakzaw mentioned are pretty cheap in ebay now. Even well working ones.

The phosphor (colour) wheel inside is of this type.


Once I tried to focus the blue beam on it, it bearnt producing a lot of smoke! So the phosphor was mostly made of organic material I think.
In this way I suppose that the internal optics of a projector is not designed to sharply focus the beam on the colour wheel but in contrary to focus it bad enough in order not to burn the material the phosphor is made of.
 

Encap

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Not sure of what you want to do--but doubt projector optics are the answer.
If you want to combine beams there are only a few ways--see : https://laserpointerforums.com/threads/reference-guide-how-to-combine-lasers.77449/

If you want to see the optics inside of a projector have a look here at DTR's site. He used to sell them after removing the laser diodes but has none in stock there is a good diagram of what optical parts are inside however: https://sites.google.com/site/dtrslasershop/home/projector-optics-mirrors-dicros-lenses-motors

You can look at a lot of diagrams of how a DLP works here: https://www.google.com/search?q=DLP+projector+optics&tbm=isch&source=iu&ictx=1&fir=BG20P0kLsL9I5M%3A%2C_9rvlg9C_bXjuM%2C_&vet=1&usg=AI4_-kR4WprzfUq_6fgSLfohKvdbVbmP9w&sa=X&ved=2ahUKEwja1s-Bu47pAhXpmHIEHWzmDTQQ9QEwAHoECAYQHA#imgrc=BG20P0kLsL9I5M:
 
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likevvii

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Short explanation: I want to make a laser engraver
Long explanation: I want to produce a "spotlight" I will use the white light produced from the phosphor wheel and collimate it with an aspheric lens.

Thank you for the posts. I had a great time reading about them.

I am in contact with a companies that offers high performance ceramic and single crystal phosphors. The static type which is just a square soldered to a copper heatsink. The static type has a limitation of about 30~70W on a 2mm spot size.
Good phosphor wheels have the capability of withstanding 100W~1000W of blue laser.
Buying the phosphor wheel is the easy part. Focusing hundreds of watts onto a small spot size is a different story for me.

I only need to focus all my diodes to a spot about 150mm away.
The projectors I see are the 4x4 nubm08 that are very spaced apart from each other. What optic do they use to converge the beams?
I always see the diode arrays, and the dichroics, but never the optic that converges and shapes the beams. Maybe it is there all along and I just don't understand it.

_____
Side question, when projectors rate themselves as "3500 ANSI lumens" or "5000 ANSI lumens" Is that rating specifying:
-Lumens produced by laser
-Lumens produced by phosphor wheel (this is what I think)
-Lumens produced out the projector front lens

Something that I am thinking about: Phosphor wheels have around 200lm/W blue laser. But once you account for the fact that the light produced by the phosphor wheel is a lambertian emission pattern, or a hemi-sphere. The transmissive optics can only, due to size and reflection angles, realistically intercept 40% of the light produced by the phosphor wheel, and the remaining 60% is lost as spill.
 

paul1598419

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You know that the light from fluorescing phosphor is not coherent and cannot actually be colimated. You can turn it into a spotlight, however.
 

Encap

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Eactly as Paul said .

See this video of how a projector produces a RGB image.

 

likevvii

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Thanks, I am learning everyday
I apologize for my constant flood of questions. I know I ask difficult questions. I poke around articles all the time and what I cant find out on my own, I ask here.


These videos show the transmissive type color wheels.
If they do show the reflective type in a demo video, it will show the laser striking the phosphor and returning as a yellow beam. That is not possible! Once a blue laser strikes a phosphor, it will no longer be a beam and will emit yellow light in all directions.
Even transmissive phosphors will emit yellow light in a sphere and not remain as a beam.

On the ebay post, the replacement wheels are the reflective phosphor type. The laser can not pass through the phosphor. And once the laser strikes the phosphor, it will no longer be a beam and will scatter in all directions in a lambertian emission pattern; like an LED. No longer a laser beam. Capturing and using this light is critical to a brightness of a laser phosphor projector.

Does anyone know how the lumen rating of a projector is calculated?
 

Cyparagon

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The lumen rating is measured, not calculated. I suppose you could estimate the output by characterizing the spectral distribution of each of the light sources, and attenuating each by the spectral absorption of each of the optical components, but an integrating sphere is cheaper and easier than all that nonsense.

"Long explanation: I want to produce a "spotlight" "

Sounds to me like leaving the projector as-is, but changing the final focusing optic would be a lot easier than the fiasco you're trying to get into.

...light from fluorescing phosphor... cannot actually be colimated. You can turn it into a spotlight, however.
That's... what a spotlight is, Paul. A collimated beam of light.
 

paul1598419

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Nice of you to leave out my qualifying part about it not being coherent. Yes, a spotlight does make a column, but doesn't meet the coherence needed to colimate a beam.
 




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