Fast, large and controllable phase modulation using dual frequency liquid crystals

Kirby, Andrew K.; Love, Gordon D.

doi:10.1364/opex.12.001470

Cited by 43 publications

(15 citation statements)

References 8 publications

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“…This response time is typically ~10 ms, but addressing via computer video output further limits the temporal resolution to ~30 ms. There have been several attempts to increase the response time of SLMs (Dayton et al, 2001; Kirby and Love, 2004), but no technique using spatially addressable SLMs has achieved multi-level phase-only modulation to perform a full OFF–ON–OFF cycle of the hologram at submillisecond timescales. Thalhammer et al (2013) recently demonstrated high-speed hologram transition using a device with an extended phase map of up to 4π and choosing the minimum route in phase shift for each pixel in between transitions.…”

Section: Discussionmentioning

confidence: 99%

Four-dimensional multi-site photolysis of caged neurotransmitters

Stricker

et al. 2013

Front. Cell. Neurosci.

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Neurons receive thousands of synaptic inputs that are distributed in space and time. The systematic study of how neurons process these inputs requires a technique to stimulate multiple yet highly targeted points of interest along the neuron's dendritic tree. Three-dimensional multi-focal patterns produced via holographic projection combined with two-photon photolysis of caged compounds can provide for highly localized release of neurotransmitters within each diffraction-limited focus, and in this way emulate simultaneous synaptic inputs to the neuron. However, this technique so far cannot achieve time-dependent stimulation patterns due to fundamental limitations of the hologram-encoding device and other factors that affect the consistency of controlled synaptic stimulation. Here, we report an advanced technique that enables the design and application of arbitrary spatio-temporal photostimulation patterns that resemble physiological synaptic inputs. By combining holographic projection with a programmable high-speed light-switching array, we have overcome temporal limitations with holographic projection, allowing us to mimic distributed activation of synaptic inputs leading to action potential generation. Our experiments uniquely demonstrate multi-site two-photon glutamate uncaging in three dimensions with submillisecond temporal resolution. Implementing this approach opens up new prospects for studying neuronal synaptic integration in four dimensions.

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Section: Discussionmentioning

confidence: 99%

Four-dimensional multi-site photolysis of caged neurotransmitters

Stricker

et al. 2013

Front. Cell. Neurosci.

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“…According to Mordi and Ciuffreda [30], however, the average latency time of accommodation of a 30-year-old individual is ~0.35 s and the time constant of accommodation amounts to ~0.2 s. Thus, a response time of ~0.5 s would be ideally suited for adaptive IOLs to correct for the eye's aberrations dynamically. A possible way to improve the overall dynamics of the LC modal lens is to use a dual-frequency LC material, see [31] and references therein, although the dynamics should be optimized together with the LC layer thickness to provide an accommodation range of up to ~ +4 D.…”

Section: Discussion and Further Workmentioning

confidence: 99%

Liquid-crystal intraocular adaptive lens with wireless control

Simonov¹,

Vdovin²,

Loktev³

2007

Opt. Express

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We present a prototype of an adaptive intraocular lens based on a modal liquid-crystal spatial phase modulator with wireless control. The modal corrector consists of a nematic liquid-crystal layer sandwiched between two glass substrates with transparent low-and high-ohmic electrodes, respectively. Adaptive correction of ocular aberrations is achieved by changing the amplitude and the frequency of the applied control voltage. The convex-shaped glass substrates provide the required initial focusing power of the lens. A loop antenna mounded on the rim of the lens delivers an amplitude-modulated radio-frequency control signal to the integrated rectifier circuit that drives the liquid-crystal modal corrector. In vitro measurements of a 5-mm clear aperture prototype with an initial focusing power of +12.5 diopter, remotely driven by a radio-frequency control unit at ~6 MHz, were carried out using a Shack-Hartmann wavefront sensor. The lens based on a 40-μm thick liquid-crystal layer allows for an adjustable defocus of 4 waves, i. e. an accommodation of ~2.51 dioptres at a wavelength of 534 nm, and correction of spherical aberration coefficient ranging from -0.8 to 0.67 waves. Frequency-switching technique was employed to increase the response speed and eliminate transient overshoots in aberration coefficients. The full-scale settling time of the adaptive modal corrector was measured to be ~4 s.

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“…It is pertinent to note that the high drive frequency as 50 kHz would possibly cause dielectric heating effects. These effects have been considered both theoretically and experimentally in [34–36]. However, in this study, the voltage in 50 kHz is applied only for the recovery stage, the time span of which is normally short as compared to the whole addressing operations, leading to no heating effect.…”

Section: Design Principlesmentioning

confidence: 99%

A New Dual-Frequency Liquid Crystal Lens with Ring-and-Pie Electrodes and a Driving Scheme to Prevent Disclination Lines and Improve Recovery Time

Kao

Chao

2011

Sensors

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A new liquid crystal lens design is proposed to improve the recovery time with a ring-and-pie electrode pattern through a suitable driving scheme and using dual-frequency liquid crystals (DFLC) MLC-2048. Compared with the conventional single hole-type liquid crystal lens, this new structure of the DFLC lens is composed of only two ITO glasses, one of which is designed with the ring-and-pie pattern. For this device, one can control the orientation of liquid crystal directors via a three-stage switching procedure on the particularly-designed ring-and-pie electrode pattern. This aims to eliminate the disclination lines, and using different drive frequencies to reduce the recovery time to be less than 5 seconds. The proposed DFLC lens is shown effective in reducing recovery time, and then serves well as a potential device in places of the conventional lenses with fixed focus lengths and the conventional LC lens with a single circular-hole electrode pattern.

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Fast, large and controllable phase modulation using dual frequency liquid crystals

Cited by 43 publications

References 8 publications

Four-dimensional multi-site photolysis of caged neurotransmitters

Four-dimensional multi-site photolysis of caged neurotransmitters

Liquid-crystal intraocular adaptive lens with wireless control

A New Dual-Frequency Liquid Crystal Lens with Ring-and-Pie Electrodes and a Driving Scheme to Prevent Disclination Lines and Improve Recovery Time

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