That's probably true for the higher end LEDs, but the junk out of China is more likely around 35-40%. LEDengin has one of the better 365nm LEDs, they only hit 50% efficiency in their top most bin. The only advantage of using the cheaper, less efficient LEDs is that the cost per milliwatt of output is far lower, so you can just brute force it. For the same number of LEDs from LEDengin, it would have cost me over $2K

 

Oh, don't get me wrong. I think you are heading down the right path. 9% might be a little on the high side for the output in 365nm +/-5nm, but you aren't too far off. For bar napkin calculations, it's a great working point.

I had thought about fluorescents. Small T8 or T5's seem to be available, but CCFL's (cold cathode fluorescents) might be an option and was what I was originally thinking of when it came to fluorescents. The only kicker is that CCFL's overall lifespan sucks when compared to LED. Even the T5's are only rated to about 3000-7000 hours (depends on the size of the bulb). Sure, that's a lot of print time, but LEDs will last virtually indefinitely in this application. Cost might be about the same too once you factor in the number of bulbs required, plus ballasts, sockets, etc...

 

Another benefit to using LEDs is that you can adjust the brightness easily to suit your needs. There may be certain resins that work a little better with lower intensities. For all we know, we may be some light bleed through the LCD at higher intensities resulting in poor print quality. This is all speculation at this point. LEDs will give us the most flexibility. It will also give is the tightest wavelength output with no wasted energy in longer wavelengths.

 

Seeing as we have been talking about 4K UHD panels recently, I want to use this post as a collection point for the various 15.6" UHD panels that I end up running across. So far I have found the following (I'll add links to free datasheets as I find them):

LG - LP156UD1-SPB1 (this is the panel that I purchased and is an RGBW panel, for what that's worth)

Sharp - LQ156D1JX01 (Physically looks almost identical to the LG panel above, but it's RGB from what I can see)

Samsung - LTN156FL02L01 (RGBW, which is odd considering Samsung's smear campaign against LG, but it has the same pixel arrangement as the LG)

Edit (10/14/2016) - Looks like all of those panels are electrically equivalent, so they can use the same Displayport adapter board (same connector and pinout). They are also all available for under $100 on eBay.

Here is the adapter board by itself for those interested

DP Board for 15.6inch 3840x2160 4K LCD LP156UD1-SPA2 LP156UD1-SPB1 LP156UD1-SPC1

 

So far, I've been using the datasheet for Makerjuice's G+ resin, mainly because it has good reviews, reasonable price, and the datasheet is readily available with the absorption curve

https://cdn.shopify.com/s/files/1/1224/0904/files/GPlus-TDS.pdf?5013488679945133065

360-385nm sees to have the best reaction. Shorter wavelengths than that seem to perform better, but the price of the light source increases exponentially as the wavelength drops (at least for LEDs). 365nm is a decent point to work from regardless of the light source type, as all arc lamps (metal halide, mercury vapor, fluorescent) utilize mercury, and that produces the 365nm peak that you see in every lamp of this type (regardless of whether it's a UV or daylight type lamp), and 365nm LEDs are getting much easier to find.

 

You mean, as the wavelength lengthens, the absorbance decreases .

This is what I ordered

10pcs/lot 1W 3W High Power UV Ultraviolet 365nm 375 395nm 400nm 410nm 420nm LED Lamp Bulb Light-in LED Bulbs & Tubes from Lights & Lighting on Aliexpress.com | Alibaba Group

I'm not expecting them to be very good for this price, but they will work for now. If we find out that we need far less output than we would get from a 1W LED array, then I can start looking at mid power LEDs like 5050's that will be a lot cheaper.

 

I was actually meaning to post about that the other day when I saw it. Would have been nice if they went into a little more detail as to what "tablet resolution" meant.

To add to the list of upcoming SLA printers, here's another one:

Ilios Beam 3D printer promises high-quality SLA printing for under $2,700

It's like a laser cutter in reverse!

 

I updated post #128 with links to datasheets as well as a link to the eDP adapter board

 

You know, I had a feeling that it was the iPad Pro. Man, what an expensive way to get the job done (comparatively). I wonder where they are getting the LCD from though. I know ebay isn't exactly a reliable source of parts for production, but you only seem to be able to get the LCD with the digitizer bonded to the screen (not good for print definition). I have yet to find the manufacturer or the part number for that display, but there is a pretty good chance it's an LG.

Similar size and resolution displays would also be the Pixel C and the Surface 4, but those are physically smaller than the iPad Pro with similar resolutions.

Panelook.com doesn't have any listing for a display with that resolution. What they do have is a listing for a 65" 8K Innolux display (186 micron XY, 56.23"x31.63")

 

I really hope it doesn't take too long to get here. I've been feverishly checking the tracking information, but China Post is notorious for not keeping up with the various details until it lands Stateside and USPS takes over.

 

Woohoo! LCD touched down in Chicago today. Should see it Monday according to USPS.

 

The LCD fairy came early!



Actually, it came Friday. Just forgot to upload the picture. Everything came perfectly packaged. Hope to get it fired up tomorrow once I find a barrel jack that will fit the adapter board.

 

I had seen that build before, but it wasn't as far along as this. His print results look great. I'm curious how he is running an iPad display and NanoDLP though.

 

In regards to my own printer, I tried firing up the 4K LCD last night. As I kind of expected, it didn't work. The ebay page did caution against using older displayport cables, and to make sure to use UHD Displayport 1.2 compliant cables. As you may have guessed, mine weren't compatible, and it left the backlight blinking randomly with nothing on the display. The other possibility as to why it didn't work was that the video card in the laptops weren't up to outputting a 3840x2160 resolution, so I picked up a USB 3.0 to Displayport 1.2 adapter that's certified for UHD resolutions. It wasn't expensive ($65), so it will be a last resort if the cable that I also picked up today doesn't quite cut it.

Now, what was interesting about the panel itself was that there isn't really a rigid frame encasing the LCD like the iPad display. With the iPad display, the housing covered the back as well as the sides. The LG panel looks like it was designed to be installed in the lid of the laptop where the lid itself is structural. I guess without getting too long winded about it all, it means that the back reflective white layer is sitting there out in the open. It's entirely possible that you could pull that layer out without too much effort, allowing for an external backlight without a lot of work.