21 August 2013

Crystal clear silicone removes reflections and improves image quality

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When mounting a protective disc on top of a light screen, e.g. an LCD, inevitably occurs disturbing reflections from the layers the light from hits. Optical lamination involves filling the gap between the LCD and the disc with an optically clear material. This eliminates all visible light reflections in the intermediate layers.

At the same time that the reflections disappear, thanks to optical lamination, you get a lot of improvements in the bargain: the image from the screen is perceived to have much clearer colors and brightness, the scattering angle increases and the contrasts increase. These things add up to a very big difference – the laminated screen is perceived as so much nicer and sleeker that most people who see the two variants side by side for the first time start to wonder what's wrong with the non-laminated screen.

If you use glass-clear silicone for lamination, you get another big advantage: the product becomes more resistant to shocks and impacts, thanks to the fact that silicone is soft and elastic.

The picture below shows how the concept works. An air gap allows the light to bounce from the underside of the glass and the top of the screen back up, which is seen as annoying reflections.

If you fill the air gap with a transparent material, the reflections of the middle layer disappear, in the image Reflection 2 and Reflection 3. What you need to supplement with is an anti-reflection treatment on the top of the disc, which can almost completely remove the top remaining reflection.

The principle of optical lamination

There are a few different varieties of materials to use for optical lamination, and silicone is a very common and technically sound solution. The advantages are numerous:

  • High light transmittance: over 95 %
  • Refractive index 1.43-1.53, depending on the product
  • Does not yellow over time
  • Not affected by even strong UV light
  • Low surface tension provides perfect lamination and filling of irregularities at the micrometer level
  • Can be cured at room temperature, heat or with UV light
  • Hardly any shrinkage – provides robust production
  • Excellent ability to absorb vibrations and impacts
  • Minimal water absorption
  • Retains its mechanical properties over a very wide temperature range

In addition to the technical advantages, silicone is very environmentally friendly because it is not classified as a thermosetting plastic. The variants for optical lamination also smell nothing and are generally very nice to work with.

Tribotec stocks and sells several different varieties of silicone for optical lamination. Feel free to contact us if you want to know more!