The effect of the wavelength-dependent scattering on the change of the color chromaticity in the lightguide panel of a liquid crystal display is examined. The white light emitted from the white LEDs located at the edge of the lightguide propagates in the lightguide and is scattered by the patterned dots that are placed on the bottom of the lightguide. The scattered lights that are far from the LEDs showed reddish color compared to the bluish color that is scattered from the near area from the LEDs. The color difference was between 0.01 to 0.06 depending on the resin and the thickness of the lightguide.

Light-emitting diodes (LED) have many advantages for dental astral lighting because of their high color rendering index (CRI), low power consumption, light weight and longer life. A dental astral lamp is specially designed and simulated for securing the extra space for installing a multimedia display that will be helpful for treating young patients. The optical system using the reverse dual reflection method consisted of four illumination modules disposed at the four corners of the dental astral lamp, and each module comprises a high power LED, an elliptical mirror, and a multifacet reflector assembly using eight cylindrical mirrors. It is shown that the required illuminance, illumination pattern, and the illumination uniformity are well satisfied.

White reflective patterns are very difficult to fabricate, due to the scattering and reflection of light, especially when the pattern size goes down to micron size. A reflective white barrier structure of height 50 μm and width 80 μm was fabricated using dry-film resist as an intermediate reverse pattern. The reverse dry-film resist pattern was coated with an SiO2 layer by sputtering, to protect the resist from chemical attack by the radical molecules in UV white resin. The UV white resin was applied on the dry-film resist pattern and then cured with ultraviolet light. The fine three-dimensional reflective patterns were finished by removing the dry-film resist.