In Exposure Unit, the role of light is very crucial. Because, the burning of screen happens only with the type of light we use. But before knowing that we need to know which type of emulsion and artwork is needed. Based on that we can decide which type of light source we should use.
The type of emulsion we better use is photo polymer emulsion. There are different photo polymer emulsions available in the market. Choose the one with the best quality. Because, it has the power to get heated very fast i.e., the exposure is high as it is sensitive to light and also maintain the heat for long time. If we use the same emulsion in a liquid form, the exposure will be too high even at poor light. In case of liquid photo polymer emulsion, the UV rays need not be high on screen as the exposure is very fast compared to solid form of photo polymer, even with less contact of screen to the UV rays. We need to check viscosity of the photo polymer emulsion. With that viscosity levels we can decide, the type of light we should use. Usually we use unfiltered light but in above case we can use the light which is bit filtered but not completely filtered as the screen should be in contact with at least a little amount of UV rays.
The artwork depends on the type of light we use. If we want to get a clear print of the artwork, we need to use the light with highest amount of UV rays to burn the screen with the good liquid emulsion. If we use filtered light, we may face the problem of getting a print of artwork. We couldn’t get a clear print of artwork as there will be many dots or lines we see in the print. We better prefer ideal light compared to fluorescent and halogen lights as it has rich UV rays. Bulbs with mercury vapour are also preferable. Bulbs with metal halide are preferable too.
We can use LED lights too for exposure of screens. LED lights are cheap, safe, easy to operate and rich in lifetime. LED is a light source which is rich in UV rays. It is user friendly and easily available in the market. In India, the distribution of LED lights is free to promote them. The resistance of LED lights is high. Even in USA, the LED lights are popular. The print by exposing the screen to LED lights is too clear and it resembles picture perfect. Hence say goodbye to ideal tubes and support usage of LED lights.