LCD/DLP resin curing system

Question

I'm trying to develop a device to burn a glass slide surface with a special pattern of UV light (between 300 nm and 360 nm) in a 5 cm square surface.

I've read several threads asking questions about LCD printers and their way of functioning but I am not entirely sure how they work. So far I have found two methods that explain LCD printers:

1. The LCD screen emits light in UV spectrum that causes the resin to cure. I don't believe there are any LCD screens that can emit at 360 nm.

2. Initially there's a UV light bulb 'behind' the LCD screen which is translucent when off. The pattern is drawn in the LCD screen interfering with UV light's path drawing the image in the plate.

If option two is the right one, do you know any devices (uv light and lcd screen) to develop what I want within the 360 nm wavelength?

Alternatively, can a DLP projector to emit UV light (by adding a UV light bulb)? Would it still need to be cured?

Answer 1

It's almost always what you call system 2:

The LCD screen is acting as a "mask" for the UV backlight, which is a strong bulb under it. This also is the reason that the screen degrades over time and that the machines need replacement bulbs: the heat from the UV source burns out the screen and itself over time. Both parts are consumable, just like the screen.

You could technically swap out the light source for any one that fits the machine. However, a 360 nm light source won't help you for printing resins at all: most resins you can buy cure between 395 and 410 nm.

Yes, even by curing with an UV light source, you need to post-cure the print. The reason for that is to get rid of any uncured, not washed away resin that still sticks to the surface and that a 3D print right of the platform actually isn't cured fully - especially the inter-layer-bonds are not formed fully and curing in the lightbox increases the stability to the print a lot.