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Development of Liquid Crystal Based Adaptive Optical elements

  • Posted by doEEEt Media Group
  • On February 11, 2020
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For Space Applications

Objectives of the project:

  • To identify, review and evaluate the current status of programmable optoelectronic adaptive elements (POE).
  • To design and manufacture a POE produced to an agreed specification (Laser steering POE).
  • To test and characterize the produced POE. A particularly important aspect of this contract is to further understanding of how the materials and technologies involved in POE structures react to environmental conditions experienced in space activities.
  • To produce a technology roadmap that identifies the main areas of application for POE technologies and the developments necessary to achieve maximal performance and durability.

Liquid Crystal Selection

Liquid crystal technology

  • Rod shape molecules that are self align creating a macroscopic uniaxial structure generally birrefringent.
    1. Standard Liquid Crystals: optical and electrical positive anisotropy — parallel
    2. VAN (Vertical Align Nematics) liquid crystals — perpendicular.
  • Fast switching
  • Reduced susceptibility to fringing
  • Less crosstalk
  • The vertical state absorbs less UV.
  • Designed to withstand high light intensity and elevated working temperature (50ºC)
CHECK THE FULL REPORT HERE
Study of transition times in a 1.5 mm thick cell (1781 A3) with 250 nm retardation

Study of transition times in a 1.5 mm thick cell (1781 A3) with 250 nm retardation

Driver design trade-off I-Chip-On-Glass</strong

  • A conventional solution for high-res micro displays
  • Technology not tested in UPM facilities
  • Impossible to separate electronics and device
  • Reduced number of external connections
  • Limited choice of drivers

–Not all display drivers are suitable for this application.

Driver design trade-off II – Flexible circuit board (FCB) or Chip-On-Flex

  • A conventional solution for high-res displays
  • Technology not tested in UPM facilities
    • Necessary to purchase externally manufactured  FCB
    • Possibility of soldering chips onto flex is studied by Emxys
  • One critical high density connector per 500 lines
  • Reduced number of external connections
  • Interconnection of the driver circuit and the ITO Tracks is done with anisotropic conductive adhesive Hitachi ANISOLM® AC-8955YW-23

Driver design trade-off II – Flexible circuit board (FCB) or Chip-On-Flex

Driving and Interconnection

The microcontroller manages the communication from the PC with the chip SSD1783 (Solomon Systech Limited) via a serial SPI bus interface and also, between the POE board and the computer (using a Bluetooth link). The team decided to implement Bluetooth communications in order to improve the usability of the system during the POE tests on the optical bench.

Driving and Interconnection

Conclusion

  • Programmable Optical Elements using Liquid Crystals is a promising technology of space use.
  • A beam steerer, foreseen to be able to withstand space environment, has been design.
  • Testing has not begun yet.
  • Driving Electronics complexity due to the high number of pixels.
  • But the driving electronics flexibility will lead to multipurpose LC devices.

Read more about all the development process in the full report below

ICSO 2010 POE Presentation

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