A homemade XGA hmd project (1024x768 for $1200!)

[3dpmaster]

I plan to make a cheap xga hmd (1024x768) with two xga mini projectors and a head tracker.

list of material.
- diy wooden or aluminium head support structure.
(tools: mini bolts, drill, screws, saw, etc.)
- lcd panel support for lcd parallax alignement.
- two Peack lenses (8x)
- two disassembled projectors of xga.
- headphones

Needs for pc
- a graphic card with 2 x vga or 2 x dvi for two pc monitors (for left and right eye)
- very long monitor cables (vga or dvi) for connection from computer to projector panel
- head tracker
- 3d games

I have to test the power voltage of the projectors without lamp. Then, disassembly the projectors, remove the fan components. Replace lamp with a mini light box and fit it on the lcd.....

PRICE DIY HMD: two projectors (2x $380) plus headtracker (~$300) plus hardware tools for assembly)

TOTAL ESTIMATION PRICE: 1200 Dollars (normally a xga hmd costs about $24k dollars)

Project launch: over a few months.

greets from Belgium!

[Johnny-Mnemonic]

Hi!
Interesting project!
What FOV do you expect to get? Personally I fan of big FOV's rather than big resolutions.

[cybereality]

Sounds interesting. I hope that works out for you. I have some plans too for projector-based HMD. I think it can be very nice.

[3dpmaster]

Sorry for this late reply

The fov would be about 100 deg but it can be higher than 120 deg with special optics. My first attempt was to make a LEEP-based lens but that could not enlarge the lcd format on the entire field.

My second attempt is to work with some huge meniscus lenses or a Nagler based eyepiece with a field of view of 100 deg (horzontal and vertical).
Here is illustration of some eyepieces used in telescopy.

fov eyepieces.gif

A Nagler eyepiece is expensive and I think the weight of one nagler eyepiece is about 0.5 kg.
If some of these lenses can be replaced with plastic ones, that would be great. The hmd has to be wearable with the projector components on the top of the head and the lcd on the front of the observers eye (if possible with longer lcd cables to reach the components).

How smaller the front, how easier to rotate your head.

[mAchiNE]

Do you know which mini projectors you are going to use? I would be interested to see pictures of the dissected projector when you pull it apart

[nrp]

I've considered doing something similar. The resolution would be only 848x480, but I was looking at using the Microvision SHOWWX. I haven't tried opening it, but I believe the lasers, mirror, and control electronics are entirely in one fairly small module like this. It is probably mildly impractical until the HDMI version comes out though.

Edit: I guess what I'm talking about is slightly different. I was thinking in terms of projecting onto some plane or curved surface, while you are talking about pulling the LCD out of the projector and using it directly with a new light source. Are there single LCD pico projectors out there? I was under the impression they were all either DLP or used 3 LCDs with a prism. I suppose you could take the entire light/prism/lcd module, but would that be too much weight hanging off the front of an HMD?

[cadcoke5]

Here is a link to a video, showing the ShowWX+ projector being partially disassembled.
http://www.youtube.com/watch?v=6qun47AK ... r_embedded" onclick="window.open(this.href);return false;
The video also shows the image being sent through some interesting optics.

Note that I got this link from a web site devoted to pico projector news.
http://www.picoprojector-info.com/" onclick="window.open(this.href);return false;

Joe Dunfee

[3dpmaster]

Dear,
What is the minimum focal distance between the projector lens and the projection screen?
The image has to stay sharp and not too big, else the HMD will lose its sence of its compactness. The projection image has to be ~2 to 2,4 inch (paralax distance) else mirror based stereoscopy with 2 bigger projection images.

I try to have an AXAA M2 projector: lcos or lcd technology (i think it is a LCOS technology).
Lcos is easy to modify by changing its light source without losing quality. (with a led softbox for example). I'm curious about the format of it's lcos for front-to-eye image.

The only problem I have is the video format. In Belgium we use PAL and not NTSC.

[3dpmaster]

Answer to 'nrp'
I'm searching for Lcd or Lcos i.s. of Dlp.
For prisms I will use cnc micropolished acrylic beamsplitter prisms (less weight) and no chromatic aberration because of its unique reflection system.

[cadcoke5]

Regarding the laser projectors, while I have never seen a minimum distance given, they have always given the distance as infinite. Remember this is not like the DLP projectors, where the light source is aimed at a surface which is (in regards to focus) the same as projecting through a LCD. Those require focusing on the image source.

The laser projectors are actually aiming the laser at a single mirror, and moving that mirror very fast to scan the laser back and forth to form the image. In my own experience with lasers, I think it is reasonable to expect essentially a minimum focus distance of 0.

Joe Dunfee

[3dpmaster]

It will work well but the laserbeam that moves with the mirror has to be very small. Prehaps, every projected dot will be projected one over an other?
But sure, a laser projected image has more color depth and contrast.

[Aeroflux]

I just happen to own the ShowWX+ and I would highly suggest you test a demo model first. The laser projector is notorious for a constant sparkle effect at close range. For me it makes text illegible and strains the eyes quickly. YMMV

[Synexious]

This is a crazy idea, but might it be possible to mount three of these for Surround? Maybe even three sets of two for 3D Surround? Assembling would probably be a chore, but aren't picos light and small enough to do something like this, in theory? How much do they weigh?

[3dpmaster]

Yes, it will be a labour.
First I will test the laser projector from inside out before buying.
If it works, I'll build a hmd with xga laser projector system.
The fov will be easy adaptive to the projecting screen (maximum 6,5 cm for IPD)
If not:
I will start my experiments with a cheap lcos vga mini projector. All I need is the lcd and the relay module without lamp and fan. Connecting the vga on a computer... I hope it works unboxed.
I will show some pictures if it works well.

[3dpmaster]

I forgot to say: the lamp will be replaced with a mini softbox.
The weight will be around 250 to 300 grams (projectors only).
The head support system is around 100 grams.
Lenses: big issue.(depends on lens system: Nagler related system)

[PalmerTech]

Oh man, those Naglers are expensive/heavy.

[nrp]

Yes, it will be a labour.
First I will test the laser projector from inside out before buying.
If it works, I'll build a hmd with xga laser projector system.
The fov will be easy adaptive to the projecting screen (maximum 6,5 cm for IPD)
If not:
I will start my experiments with a cheap lcos vga mini projector. All I need is the lcd and the relay module without lamp and fan. Connecting the vga on a computer... I hope it works unboxed.
I will show some pictures if it works well.

Where are you getting an XGA laser projector? The only three portable laser projectors I know of are the SHOWWX, the Light Touch, and the AAXA L1. The first two are WVGA and the last one is SVGA.

[3dpmaster]

After a few times I would have enough money to buy the mini projector, joepie!
Now I figure out with Peack lenses, meniscus lenses, mirrors, and one diapositive (35mm).

I dissanbly a dia projector and I pickend this one (condenser lens)

http://www.google.be/imgres?q=condenser ... ex-Thread-(condensers" onclick="window.open(this.href);return false;)&docid=W1IPXn89pfqPyM&w=316&h=227&ei=igOOTvL7CIP1-gbN9tXtCg&zoom=1&iact=hc&vpx=92&vpy=306&dur=450&hovh=159&hovw=218&tx=126&ty=117&page=3&tbnh=109&tbnw=139&start=33&ndsp=17&ved=1t:429,r:0,s:33

The problem is the chromatic aberration (it is not a doublet)

Nagahara's proposition is one of the best solution for a true human fov. However, the hmd has vignette problems.

The second patent is only good in dark rooms for a good vision.
http://www.youtube.com/watch?v=2rvDYF7XCjw" onclick="window.open(this.href);return false;

An other posibility for less optical weight is a concave mirror in front of the observer's eye and a beamsplitter between the mirror and the eye. It can give more than 100 deg fov.

The last one would be easy with a huge polished ice spoon for example.

...be continued.

[3dpmaster]

This is the one I'm waiting for disassembly

[3dpmaster]

Only change the optics for a larger fov LOL

[3dpmaster]

first trial of making a ellips- like mandrel for curved mirror (without cnc machining)

materials: mirror curve path, drill press & mill

[3dpmaster]

on the way to make a curved mirror diy HMD with 180 DEG FIELD OF VIEW with + Cinemizer oled 720p
With the Cinemizer 720p, the image will be bright enough for a wide fov coverage. I do not need two projectors anymore, only one pair of videogoggles and some diy optics. So finally the xga project is a bit modified but still possible. (only the 48 lost pixels from the 720p)

[PalmerTech]

Wow, very impressive!

Where did you get the info that the Cinemizer OLED displays are bright enough? The Sony OLEDs are pretty dim, and even the Emagin units don't put out all that much light.