Nanoparticle doped liquid crystal device for laser speckle reduction

Abstract

An optical display device includes a coherent light source generating a coherent light beam in visible, ultraviolet, or infrared ranges. The coherent light beam is directed at a liquid crystal component. A plurality of liquid crystals and a plurality of nanoparticles having an average diameter of ≤about 450 nm are disposed in an interior compartment. An electrical source is in electrical communication with the first and the second electrodes. When no voltage or current is applied, a filtered light beam transmitted or reflected from the liquid crystal component exhibits a first speckle contrast ≥about 0.28. When voltage or current is applied, the microparticles are induced to move and the filtered light beam has a second speckle contrast that is ≤about 0.2 and in certain aspects may be ≤about 0.03. A method of reducing speckle in an optical device having a coherent light source is also provided.

Description

INTRODUCTION[0001]This section provides background information related to the present disclosure which is not necessarily prior art.[0002]The present disclosure pertains to an optical device, such as a display device, that includes a coherent light source generating a coherent light beam in a visible range, an ultraviolet range, or an infrared range and a liquid crystal component comprising a plurality of liquid crystals and a plurality of nanoparticles. In certain aspects, the optical device reduces speckle contrast of the coherent light beam to less than or equal to about 0.2. Methods of reducing speckle in an optical device having a coherent light source are also provided.[0003]Display devices are used in a variety of applications. The techniques described in this disclosure are generally applicable to a variety of display devices, including any either transmission or reflection type flat panel display, especially three-dimensional projection displays. For example, a vehicle may ...

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Benefits of technology

[0004]Various display systems often employ a source of coherent light, such as a laser, in conjunction with the other display components, like LCD components. However, using a laser as an illumination source can potentially create a large amount of speckle that arises from coherence of the laser. When coherent light is reflected from a diffused surface, various points on the surface each emit a light wave. Typically, all of the reflected light waves have the same frequency, but the phase and amplitude of the light reflected from different points on the surface can vary. The light can thus interfere constructively and destructively to produce a pattern of light and dark spots or bands that appear to be random, which are considered to be speckles. When forming an image from the reflected light, the speckle effect can add noise to the image.SUMMARY

[0026]The present disclosure also further relates to a method of reducing speckle in an optical device having a coherent light source. The method includes directing a coherent light beam generated by the coherent light source having a wavelength in a visible range, an ultraviolet range, or infrared range towards a liquid crystal component including a first electrode configured to transmit the coherent light beam, a second electrode configured to transmit or reflect the coherent light beam, and at least one spacer disposed between the first electrode and the second electrode to define an interior compartment therebetween. The liquid crystal component also includes a plurality of liquid crystals disposed in the interior compartment having a first refractive index and selected from the group consisting of ferroelectric liquid crystals and negative nematic liquid crystals. A plurality of nanoparticles having a second refractive index and an average diameter of less than or equal to about 450 nm is also disposed in the interior compartment. A difference between the first refractive index and the second refractive index is greater than 0 to less than or equal to about 0.5. An electrical source in electrical communication with the first electrode and the second electrode. The method includes applying electrical energy via the electrical source to the first electrode and the second electrode of the liquid crystal component to induce random domains in the plurality of liquid crystals and reduce a speckle contrast of the coherent light beam transmitted or reflected from the liquid crystal component to less than or equal to about 0.2.

[0029]In one aspect, the plurality of liquid crystals includes negative nematic liquid crystals and the applying electrical energy generates a top-down electrical field to induce instability and generate random domains in the plurality of liquid crystals to create a temporal averaging effect.

Problems solved by technology

However, using a laser as an illumination source can potentially create a large amount of speckle that arises from coherence of the laser.

The light can thus interfere constructively and destructively to produce a pattern of light and dark spots or bands that appear to be random, which are considered to be speckles.

When forming an image from the reflected light, the speckle effect can add noise to the image.

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