Fundamentals of liquid crystals and other liquid display technologies

Castellano, Joseph A.

doi:10.1016/0030-3992(75)90007-9

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…It is beyond the purpose of this section to describe the pixelated LC-SLM technology in details, as this has been already extensively covered elsewhere. [19][20][21] Of main interest for high-contrast applications is the liquid crystal on-silicon (LCOS) sub-category, 22 which can operate in reflection configuration with very compelling performance metrics in terms of fillfactor, pixel pitch, modulation dynamic range, and framerate. The main working principle of a parallel-aligned nematic (PAN) LCOS SLM panel arises from a linearly-polarized impending beam seeing variable birefringence depending on the amount of tilt of the LC molecules, which is a function of the induced pixel-scale electric field (see Figure 1 in Kühn et al 2016).…”

Section: Spatial-light Modulators (Slm) As Focal-plane Phase Coronagrmentioning

confidence: 99%

SLM-based digital adaptive coronagraphy: current status and capabilities

Kühn

Patapis

et al. 2018

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III

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Active coronagraphy is deemed to play a key role for the next generation of high-contrast instruments, notably in order to deal with large segmented mirrors that might exhibit time-dependent pupil merit function, caused by missing or defective segments. To this purpose, we recently introduced a new technological framework called digital adaptive coronagraphy (DAC), making use of liquid-crystal spatial light modulators (SLMs) display panels operating as active focal-plane phase mask coronagraphs. Here, we first review the latest contrast performance, measured in laboratory conditions with monochromatic visible light, and describe a few potential pathways to improve SLM coronagraphic nulling in the future. We then unveil a few unique capabilities of SLM-based DAC that were recently, or are currently in the process of being, demonstrated in our laboratory, including NCPA wavefront sensing, aperture-matched adaptive phase masks, coronagraphic nulling of multiple star systems, and coherent differential imaging (CDI).

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Section: Spatial-light Modulators (Slm) As Focal-plane Phase Coronagrmentioning

confidence: 99%

SLM-based digital adaptive coronagraphy: current status and capabilities

Kühn

Patapis

et al. 2018

Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation III

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“…The functional details of liquid crystals (LC) SLM panels have been described in-depth elsewhere [27][28][29][30], and the study of their technical relevance and hardware limitations as adaptive coronagraphs for high-contrast imaging is currently still work-in-progress [26], thus not described in details herein. As a brief description, PAN-LCOS panels enable pixelated phase-only modulation of a linearly polarized incoming wavefront, by applying an electric field to each individual pixel cell to proportionally tilt the LC molecules along the z-axis, which will vary the amount of birefringence induced by the LC cell, and in turn modulate the phase for linearly polarized incoming light.…”

Section: A Pan-lcos Spatial Light Modulator As An Adaptive Focal-planmentioning

confidence: 99%

Implementing focal-plane phase masks optimized for real telescope apertures with SLM-based digital adaptive coronagraphy

Kühn¹,

Patapis²,

Ruane³

et al. 2017

Opt. Express

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Direct imaging of exoplanets or circumstellar disk material requires extreme contrast at the 10 -6 to 10 -12 levels at < 100 mas angular separation from the star. Focal-plane mask (FPM) coronagraphic imaging has played a key role in this field, taking advantage of progress in Adaptive Optics on ground-based 8+m class telescopes. However, large telescope entrance pupils usually consist of complex, sometimes segmented, non-ideal apertures, which include a central obstruction for the secondary mirror and its support structure. In practice, this negatively impacts wavefront quality and coronagraphic performance, in terms of achievable contrast and inner working angle. Recent theoretical works on structured darkness have shown that solutions for FPM phase profiles, optimized for non-ideal apertures, can be numerically derived. Here we present and discuss a first experimental validation of this concept, using reflective liquid crystal spatial light modulators as adaptive FPM coronagraphs.

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“…In our own experience over the past 2 years we find that polymeric liquid crystals respond very slowly if at all to surface forces as revealed by optical microscopy. On the other hand, small-molecule thermotropics become completely aligned in response to surface forces in times well under 1 s. 10 In light of these observations, it has been our objective to understand the principles and limitations of surface forces affecting molecular organization in polymeric systems. We report here on the alignment kinetics that result as a consequence of coupling both magnetic and surface forces.…”

mentioning

confidence: 99%