Optical Filters

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Optolite™ Clear HSR Optical Filters

Optolite™ Clear HSR (High scratch resistance) is a highly durable optically clear material. Key features include high chemical, scratch and impact resistance. It is especially suited to LCD’s and other display applications (Instrument covers, windows) where these characteristics are of a particular importance. An early version of this polymer was sold under the trade name CR-39®. Overall, our HSR material combines the optical quality and chemical resistance of glass with the lightweight performance of plastic.

Examples of applications which require an HSR optical window:

  • Avionics displays
  • Barcode scanners
  • Industrial instruments
  • Medical device instruments
  • Navigation instruments
  • Oscilloscopes
  • Scanning devices
  • Security sensors
  • Test equipment
  • Military displays
  • Automotive displays

LCD’s often suffer from a number of problems:

  • Soft front surface polariser
    – can be subject to damage from scratching, dirt, moisture, finger marks, etc.
  • Front surface reflections
    – in certain lighting conditions these may cause display reading difficulties
  • Restricted viewing angles
    – caused by LCD construction and method of operating
  • Possible Ultra Violet degradation in strong sunlight
  • Shielding from electromagnetic interference
  • Sourcing of bezels
    – not always possible or feasible with so many different LCD sizes available

Choice of Optolite Clear HSR

Instrument Plastics Ltd offers their Optolite Clear HSR (High Scratch Resistant) filter to overcome these problems on LCD’s. It is also especially recommended in display applications requiring the characteristics mentioned below.

Optolite Clear HSR has both outstanding abrasion resistance, up to 20 times that of acrylics, and excellent impact resistance. It is also chemical resistant, being immune to the effects of virtually all common solvents. It is lightweight, approximately half that of glass, and exhibits optical properties comparable to crown glass. Its maximum continuous operating temperature is in excess of 100°C.

Optolite Clear HSR is available with selected optional cast-in non-glare finishes to overcome front surface reflections. These finishes can improve readability whilst offering advantages in that they cannot chip, peel or rub off.

Optolite Clear HSR is cast in-house down to 0.5mm thickness for applications where maximum viewing angle is required or where space is at a premium. Thicker filters are manufactured for when impact resistance takes priority. Tight thickness tolerances are supplied for specialised applications.

An optional Ultra-Violet inhibitor additive can also be incorporated within the cast HSR material. This additive blocks UVA which is the UV next to blue light in the visible region. UVA HSR can be used to help protect materials from harmful ultra-violet found in strong sunlight.

A further option incorporates a blackened stainless steel mesh for electromagnetic shielding. Full edge termination service is available. These mesh filters typically give a protection of 60-70dB over the frequency range 100KHz to 1GHz. Effective shielding is becoming increasing important with the introduction of new legislation.


In applications where bright LED's cause "burn out" or uneven illumination of display, Optolite™ Diffusers soften the light and give an even illumination.

Instrument Plastics Ltd also offers full silk screening services. A silk screened border onto the reverse side of the filter and perhaps incorporating a logo, provides an attractive and inexpensive way of producing a bezel.

This may also enhance the aesthetic appearance of the system. Double sided adhesive tape can be used for attaching the filter quickly and easily to the display.

To view technical data tables please download the data sheet PDF.

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