Build Your Own SLA/SLS

Just a little confirmation for you guys, i tried a cheap 7" screen (http://www.aliexpress.com/item/Original ... 7.html?s=p) from a Raspberry Pi to blow some uv light through it, but the lcd blocks pretty much all uv light. I tried several lamps and leds and no success. I even ripped to polarizers from both sides as i know they sometimes have uv blocker, but as it has a led backlight, there was no uv blocker on the foil. So i tried the bare lcd screen und pushed some uv light on it and even then i didn´t got uv light on the other side.

I know this system is working in general as i used a 17" with ccfl backlight back in the days to verify the combination. I´ll try to find another cheap one and test it, but this time with ccfl backlight.

I think the main problem with color LCD's is the color filters, first off Red and Green completely block any usable light, then the blue filter is going to be tuned to a certain wavelength. Probably around 440-450nm.

Using LED's is pretty much needed, lamps and bulbs dont work and wont give even enough light. No point in trying any light source thats less than 400nm as its going to be blocked by the polarizers and the liquid crystals.

So the next step is finding the right LED wavelength for your LCD so you can pass as much usable light through as you can. Im going to experiment with some 440-450nm LED's and color LCD's to see if I can get it working better. I think the 9.6" Ipad3 LCD is the best candidate as its cheap and high resolution. Im also going to experiment with different optics, I can get the LEDs primary optics made in 60 degree so that might remove the need for secondary lenses like im using now. Normal LED's spread light out in all directions (~120 degrees) Only forward moving light can pass through the LCD so the majority is wasted. Lenses of 60 degrees or less will help a lot in getting more usable light through the LCD.

Interesting

If i remember correctly, i cured uv resin through a polarizer at 365nm. I´ll try it again tomorrow and post the results.

You would need to post some exact numbers, so we can exclude any misleading information.

Like if you used sub 400nm leds, you would label the lcd as unusable when if fact it might very well be quite ok, if used with 405nm leds, or 410 or 420 etc.
Or if you used leds without lenses and the light was scattered, also not the lcds fault. The surface size of the resin against how many leds underneath the lcd, also a BIG factor. Power supply and led circuit? Distance of the array from lcd?

Many variables need to be taken into account before dismissing an lcd, it would be a shame if we accidentally move over a solution that could be "it".

Feel free to do whatever scientific test you want

http://www.ebay.de/itm/291276290537?_tr ... EBIDX%3AIT

My test worked at a 17" tft and if its not working at another one, its not sufficient for me, regardless wavelenghts etc.

I've successfully cured Makerjuice SF Red Resin through the Adafruit 5" raspberry pi display using an array of 3W 410nm LEDs and 60 degree lens (purchased from an ebay supplier)

First test showed roughly 150 microns for a 15 second exposure

@steve.strong
First up, congratulations on your successful experiments with color LCD.
Care to share what exactly you did? Thanks in advance

Testing has only been very ad hoc so far. Nothing more than the pulling the backlight panel off of the LCD and propping it up over the LED array (which I'm powering directly off of a 12V line). Used a ziploc bag as a vat floor.

I'll try to get more details posted in the next couple of weeks.

Can't wait to have your detailed post, Steve!

I did another test and even with a 50W led there is no uv light on the other side of the lcd. I can easily push some uv light through an old 17" tft screen with the exact same setup, so this definately won´t work.