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FrozenGate by Avery

Testing the Microvision SHOWWX and AXAA L1 Laser Pico Projectors

cjyetman: Yes, the Microvision's green is a frequency doubled IR laser. When I ran the projector's light through a spectrometer I also detected ~1064nm and 800-something nm light, but these were very weak (definitely at safe levels). Sorry I didn't get to post the graphs for these. I'll post them next time I'm by that particular lab.
 





Someone wanted to see a video of the video projector's image in slow motion. So for your viewing pleasure, here is a 1 second video of the SHOWWX at 1000 frames per second (played back at 30 fps):

Link to video
 
Hi,
I am new to this forum and in fact I am not very well informed about projectors, but I have to make a buying decision and I would greatly appreciate your help, specially from dsholz that wrote such a nice review.

I am a biology researcher and I am using pico projectors to stimulate visually some fish and studying their behavior. I have been using an Adapt ADPP-305 LED projector that we bought because of its high light intensity (45 lumens) but, unfortunately, it is not good since it doesn't deliver truely black blacks (they turn out to be grayish), because of the LED backlight illumination. For my experiments, it's necessary to do not have any light in the blacks and produce nice bright whites (i.e., a good contrast), so I turned my attention to these two laser pico projectors, that seem to do so, even though they are not super bright. I understand that DLP technology could help too...

I will use the projector for different studies, but I will be mainly projecting rather small white dots moving around a black background. Which one of this two projectors would you suggest? From what I read, it seems that the Microvision is better at producing bright whites and absolute blacks, and seems to have a similar perceived intensity eventhough it produces less lumens... I am a little worried about speckles since I am going to project in rather small surfaces... Anyway, I would be extremely grateful for your comments....

Cheers!
 
seb,

None of the projectors project black. Black is perceived by contrast to the color being projected. So black is a trick your eye plays with you in your brain.

The projectors that have either the Texas Instruments DLP chips or LCoS chips are rectangular panels of pixel reflectors that are bathed in light and reflect out light for the desired pixels - the pixels that they want to be black must absorb the unwanted light within the panel or reflect to an area to be absorbed (the Adapt uses an LCoS panel). These panels are not able to keep some bleed through into areas that they want to be 100% black. So when you look at these projectors in a dark room, you will see some of this grayness where blacks are supposed to be.


The Microvision projector is different than the panel types because the image is built pixel by pixel by very precisely shaped laser beam reflecting off a scanning mirror in a raster pattern onto the screen. When a black pixel is desired, the light is turned off - this produces excellent contrast and perceived blacks - and the color of each pixel is produced one pixel at a time so color fidelity is excellent.

Speckle is and issue that you will have to evaluate in the setting you are using - most people that see the speckle at first don't seem to notice it after awhile or are not bothered by it. The material that is the screen causes the speckle - rough surfaces will create the most speckle. You could create a target area that does not make speckle by using special screen material or by having a very smooth surface.

Microvision will be introducing a new projector in a couple days/weeks that should be 50% brighter and have less speckle - so watch out for this new version

good luck with the research
 
Thank you hometon for your response and explanation, and I am sorry for taking so long to answer back...

So, it seems that the Microvision one is the one to go for. I thought that the DLP chips would be enough to turn away the light efficiently from black areas because of its tiny mirrors. But I guess that turning the laser off while scanning this black areas (as I understood the Microvision does) is the clever thing to do...

Good to know that an enhanced Microvision projector is coming out, I think I will probably wait for it, if it does not take too long!

Me and my research fishes thank you!
:)
 
Why noone still opened one of them? want to know whats inside...
Probably we will have the most compact RGB "Diode" for just 300$ now !
 
Hi all,

I get the showwx+ (50% brighter than showwx) from amazon to France and I love it:)

The Green laser is not a DPSS (808nm pump diode and Nd-vanadate + ktp doubler, system well known here.)

Microvision use the G-1000 green lasers from Corning, it's a special SHG (second harmonic generation, direct 1060 IR diode + doubler only!) green laser. This Green Laser G-1000 will be one of the most highly efficient, highest blanking speed and smallest size, for the moment.

As you can read on the web, Corning stop this "synthetic green laser" because the arrival of direct green laser diodes is imminent.

This green system will probably never find in a commercial laser pointer... lol
unless I dismantles a "old" showwx v1 next time, I'd like to see the white laser source and make a pocket lasershow ! lol

Have a Joyous Holiday Season!
Pascal
 

Attachments

Re: Testing the Microvision SHOWWX Laser Pico Projector

dsholz said:
the L1 [...] laser colors have the same polarization (unlike the perpendicular ones of the SHOWWX).
Click to expand...

So we could do RealD-3D with them?? :eg:

-> 2x L1 Projectors, rotate the diodes 90° in one of them, build a fancy soft that splits R-image and L-image to two VGA outs, overlap the projections and - pew! 3d home cinema
 
I own a ShowWX, but I have to use it one more time on May 31st. After that, I will tear it down. :)

EDIT: Never mind, doing it now. :P

EDIT2: Well, there is a single large FFC that terminates into three plugs. One plug powers the red and blue, one powers the green, and the other powers the MEMS mirror assembly. I tried simple unplugging the MEMS plug, but as I suspected, it would not power the lasers (I have read some of the Microvision FAQs where they answer what would happen if the MEMS assembly stopped working, and they claim it has safety measures that shut down to the unit, to prevent eye damage).

Bleh, looks like I might have to physically remove the MEMS mirror from the optical path, but leave it running.

EDIT 3: Okay, did it! I have it working as an RGB laser now. :) I need to test it out more before I do a writeup.
 
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I am going to have to take photos tomorrow, no good lighting right now.

I had it working for a while being driven off the ShowWX board, only had to remove a single mirror from the optical assembly to let the combined beam get out!

The problems started when I decided to try and run the diodes off my own drivers, to slim it down. Somehow, my driver killed the red diode, despite only setting it to 50mw. :facepalm: Here is the main problem with the optics: The convergence is really not that great. At 20 feet, it splits into a clearly visible green, red, and blue dot. Apparently, they can correct for this in software, by adjusting the point at which the lasers turn on and off, but it does not make for a very good RGB laser.
 
Can you provide any insight into what sized diodes you think the RED and BLUE are? Are they 5.6mm ?
 
No, they are not 5.6mm, sadly. They look a little smaller, 3.5mm perhaps? I am not familiar with more exotic diode sizes, I will use the digital caliper from my work tomorrow to check for sure.
 
A note, only B&W video sources from long ago are exactly 30 Hz. Standard video is 29.97 frames per second, and when you add in the sync periods at the start of the frame, this is why your seeing the banding at 1/60th.

When the VGA standards were written, 59.94 was the 2X carryover from the NTSC 29.97.

This was done right after World War II so that color video sync signals could be derived from a 3.579545 mhz color subcarrier in analog video with simple phase locked loops and counters in the camera.

Steve
 
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