405nm + TFT Screen = projection?

• Dec 29, 2011

• #1

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zealon

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Hi all,

I want to build a laser image projector like this one:

Laser Image Projector

but instead of projecting diapositives, I'd like to project images showing in a TFT LCD screen, like this one:

Experiment: DIY iPod laser youtube video projector - Step 1 - YouTube

Is it possible to project images with a 405nm laser instead of a red one?
What about image quality and laser power loss after going through the TFT?
:thinking:
TIA

 

• Dec 29, 2011

• #2

chipdouglas

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thats not what we call a laser projector. in the second vid, the guy is just using the laser as a back light for his lcd he took apart and the laser happens to be projecting the images on to the wall. lasers are coheret and because of that the are very good at creating perfect "shadows"

 

• Dec 30, 2011

• #3

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zealon

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Ok, then its a 405nm laser back light LCD. In the DIY iPod experiment, the red laser looks unfocused and not colimated.

For a 405nm focused and colimated laser, I'd like to know:

LCDs are polarized, should this laser go through it?
Would it be difficult to align laser polarization with LCD polarized filters?
Would the projected image quality be good if the laser "dot" is large, like in the laser image projector example?

TIA

 

Last edited: Dec 30, 2011

• Dec 30, 2011

• #4

chipdouglas

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i assume it would look just like the red but be violet instead. if your polarization is off just rotate the laser.

 

• Dec 30, 2011

• #5

BShanahan14rulz

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One thing to look out for is the "blooming" effect that those low visible wavelengths have. Might not be best for perceived image quality.

 

• Dec 30, 2011

• #6

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zealon

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Thanks all for your help.
I want to project images for ultraviolet (UV) curing or PCB etching.
The TFT LCD will show a "white color" image, but actually it will be violet because of 405nm laser back light. This image will be projected onto a PCB or UV-curing sensitive layer.
Do you think its possible?

TIA

 

• Jan 9, 2012

• #7

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zealon

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Anyone tried projecting images with a laser-backlit TFT?
If someone did, can you post a link to a video, pictures or information?

TIA