Advanced Methods for Improving the Efficiency of a Shack Hartmann Wavefront Sensor

Vyas, Mukesh; Prasad, B. Raghavendra

doi:10.5772/29884

Cited by 2 publications

(1 citation statement)

References 42 publications

(44 reference statements)

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“…The use of a HS WFS in microscopy is complicated by the fact that a suitable guide star may not be present and instead a confocal sensing technique has been proposed to limit the axial depth [8]. Moreover, the ability of the HS WFS in precisely estimating the wavefront shape depends on the number of detector pixels corresponding to a single sub-aperture, centroiding errors and noise mechanisms [7,9,10].…”

Section: Introductionmentioning

confidence: 99%

A direct comparison between a MEMS deformable mirror and a liquid crystal spatial light modulator in signal-based wavefront sensing

Jewel

Akondi

Vohnsen

2013

J. Eur. Opt. Soc.-Rapid Publ.

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Aberrations degrade the performance of optical systems in terms of resolution and signal-to-noise ratio. This work explores the feasibility of a signal-based wavefront sensor, which employs a search algorithm to estimate Zernike coefficients of given aberrations. The search algorithm was supported by Gaussian interpolation. The performance of two different reflective wavefront correctors, a deformable mirror and a spatial light modulator in signal-based wavefront sensing, was compared under identical conditions. The aberrations were introduced by using another identical high resolution reflecting spatial light modulator. The performance was quantified using the Strehl ratio, which was estimated from simultaneously acquired Hartmann-Shack measurements of Zernike coefficients. We find that the spatial light modulator can be a good alternative to the deformable mirror in terms of dynamic range and sensitivity, when speed is not a limiting factor. Distinct advantages of the spatial light modulator are high number of pixels and a larger active area.

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Section: Introductionmentioning

confidence: 99%

A direct comparison between a MEMS deformable mirror and a liquid crystal spatial light modulator in signal-based wavefront sensing

Jewel

Akondi

Vohnsen

2013

J. Eur. Opt. Soc.-Rapid Publ.

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Closed-loop adaptive optics using a spatial light modulator for sensing and compensating of optical aberrations in ophthalmic applications

2014

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Sensing and compensating of optical aberrations in closed-loop mode using a single spatial light modulator (SLM) for ophthalmic applications is demonstrated. Notwithstanding the disadvantages of the SLM, in certain cases, this multitasking capability of the device makes it advantageous over existing deformable mirrors (DMs), which are expensive and in general used for aberration compensation alone. A closed-loop adaptive optics (AO) system based on a single SLM was built. Beam resizing optics were used to utilize the large active area of the device and hence make it feasible to generate 137 active subapertures for wavefront sensing. While correcting Zernike aberrations up to fourth order introduced with the help of a DM (for testing purposes), diffraction-limited resolution was achieved. It is shown that matched filter and intensity-weighted centroiding techniques stand out among others. Closed-loop wavefront correction of aberrations in backscattered light from the eyes of three healthy human subjects was demonstrated after satisfactory results were obtained using an artificial eye, which was simulated with a short focal length lens and a sheet of white paper as diffuser. It is shown that the closed-loop AO system based on a single SLM is capable of diffraction-limited correction for ophthalmic applications.

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Advanced Methods for Improving the Efficiency of a Shack Hartmann Wavefront Sensor

Cited by 2 publications

References 42 publications

A direct comparison between a MEMS deformable mirror and a liquid crystal spatial light modulator in signal-based wavefront sensing

A direct comparison between a MEMS deformable mirror and a liquid crystal spatial light modulator in signal-based wavefront sensing

Closed-loop adaptive optics using a spatial light modulator for sensing and compensating of optical aberrations in ophthalmic applications

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