Rear Projection HD TV Optics - Lots of Pics!

I pulled all these out of an old tv. Obviously just some basic lenses and some dicros but theres some other pieces I was hoping someone could Identify.

Here a pic of most of the pieces. In the plastic wrap is a assortment of dicros, fs mirrors, and other colored glass pieces.





I think these are little deffraction gratings. They split the beam into tons of points.



Not sure if this is of any use but its big! :crackup:



On to the main object of my interest!

What is this?




When you shine a light through it it gets interesting!


Im thinking a combining cube. Im not sure what all the little attached pieces do...might just pull them off





On another note:

Im sure this has been shown but I found a great way to find out what wavelength a dicro reflects and passes!


Works great for 445nm!

It looks to be a nice cube

You can combine red green and blue into a single beam with that..

wannaburn said:

It looks to be a nice cube

You can combine red green and blue into a single beam with that..

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Thats what I was hoping! Should I take the small lenses off of the cube? im not sure exactly what they do.

Also when I shine a 532nm, 660nm, or even 445nm through the cube it comes out all sides with significant brightness unlike the appropriate dicro...can I do anything about this? Am i doing something wrong?

The squares attached to the cube are polarizing filters, they work with the items you called diffraction gratings which were the LCD panels to create the displayed image. The RGB cubes are cool but often are very inefficient at combining lasers.

MarioMaster said:

The squares attached to the cube are polarizing filters, they work with the items you called diffraction gratings which were the LCD panels to create the displayed image. The RGB cubes are cool but often are very inefficient at combining lasers.

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I actually thought they were little LCD windows as thats how I understand the system to work but when I shined a laser through and saw they way it behaved I didnt know how exactly to describe them.

I hope you cant just order and replace the little windows cause thats all that was wrong with this TV you can even see the defective one in the pictures :thinking:

For combining purposes should I remove the polarizing filters?

EDIT:

I pulled everything off but the mount as it will make it easier to secure to a base.


The output from the flashlight is much cleaner now and it seems to distribute the different wavelengths more correctly. Green shines right through with very little on the other sides. Red shines in and turns out the output side but a significant amount goes straight through as well. The only blues I have are over 1000mW so I didnt play with those much but I would hope it will be the same story.

Id love to use this thing but I worry that if I have this assembled correctly ill have laser diodes shining directly into laser diodes... seems like the dicro method might be best.

Does anyone have pictures or video of this type of setup?

I very roughly mocked up a combiner using upside down saucers, drink coasters, and scrap paper adjusting shims

Turned out pretty good though in my opinion!

You can see the reflection of other beams on the tips of the lasers but it seemed to work pretty well even so.


40-60mW 405nm through smoky bottle


250mW 660nm


30mW 532nm


660nm + 532nm





405nm + 532nm - sort of looks like 445nm




405nm + 660nm


AND the mythical WHITE :drool:




Now I have to admit that the camera seems to help blend the colors quite a bit. In real life up close you can see multiple colors in the beam but messing around with correct focusing etc should remedy this. :beer:

Fun for a spur of the moment little project!

Oooh fun, that looks bad ass. Any idea where one could get their hands on a cheap combining cube?

extremeodd said:

Oooh fun, that looks bad ass. Any idea where one could get their hands on a cheap combining cube?

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look on ebay for broken projectors. Just make sure that they use 3CCD technology, should say in the item listing. I know Rob(phoenix77) has a few cubes he may be willing to sell. (2 of them he got from me)

Thats one nice hefty cube you got there.

extremeodd said:

Oooh fun, that looks bad ass. Any idea where one could get their hands on a cheap combining cube?

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Check craigslist for rear projection style TVs. I dont think they all have cubes depending on the actual model but they all have lots of fun optics!

Gryphon said:

Thats one nice hefty cube you got there.

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:thanks:

Braddubya said:

rear projection style TVs. I dont think they all have cubes

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As long as it used 3CCD technology it will have a cube, as I stated above.

Sorry to thread resurrect but I just pulled apart my dead LCD projector and it had the same combining cube. So that is another good source... you can find these dirt cheap or free.

Gratuitous HeNe pic using the cube as a splitter and some of the other optics as a beam expander...

What surface do you have there? looks like an optical table/breadboard to work on, but those are incredibly expensive!

Bluefan said:

What surface do you have there? looks like an optical table/breadboard to work on, but those are incredibly expensive!

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DIY Optical table. 36" X 24" approx, 1/4 inch thick Aluminum plate with 1/4-20 tapped holes at 1" spacing. I built it a few years ago. Its an easy but very time consuming build.

Any LCD based projector or TV, 3 chip DLP, or 3 chip ILDA tv (JVC have been the only ones i've seen use ILDA) will have a similar cube.

Of these, as mentioned, LCD based ones will be the cheapest to acquire.