Measurement of eye aberrations in a speckle field

Larichev, A. V.; Ivanov, Pavel; Iroshnikov, N. G.; Shmal'gauzen, V I

doi:10.1070/qe2002v032n02abeh013091

Cited by 2 publications

(4 citation statements)

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“…The use of an SLD reduces the amount of speckle in the wavefront signal. However, due to the high frame rate utilized, speckle is still a major source of noise [10,11,12]; hence the need for a scanner (S). The expanding beam from the single mode fiber is collimated using a microscope objective producing an approximately 2 mm diameter beam sent into the eye.…”

Section: Introductionmentioning

confidence: 99%

Benefit of higher closed�??loop bandwidths in ocular adaptive optics

et al. 2003

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We present an ocular adaptive optics system with a wavefront sampling rate of 240 Hz and maximum recorded closed-loop bandwidth close to 25 Hz, but with typical performances around 10 Hz. The measured bandwidth depended on the specific system configuration and the particular subject tested. An analysis of the system performance as a function of achieved bandwidth showed consistently higher Strehl ratios for higher closed-loop bandwidths. This may be attributed to a combination of limitations on the available technology and the dynamics of ocular aberrations. We observed dynamic behaviour with a maximum frequency content around 30 Hz.

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Section: Introductionmentioning

confidence: 99%

Benefit of higher closed�??loop bandwidths in ocular adaptive optics

et al. 2003

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“…In our case, the philosophy behind the method differs from that in other proposed speckle reduction methods [13][14][15][16][17][18][19]. Instead of trying to eliminate the speckle noise in the SH CCD sensor, in our case, its presence is assumed and accepted, and it will be reduced using computer-based methods.…”

Section: Introductionmentioning

confidence: 99%

“…The nonlinear response and the restricted dynamic range imaging capabilities of the SH sensor reduce the accuracy (indeed the possibility) of the reconstructed wavefront. This problem typically arises in the cases of ocular wavefront sensing where a strong speckle field is formed by random interference of the coherent laser beam with the highly anisotropic tissues that form the retina [13][14][15][16][17]. Another case is the optical quality measurement of an instrument with rough surfaces [19].…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, these devices can be used for wavefront reconstruction of coherent or incoherent optical beams. One of the main factors that restricts the performance of the SH sensor is the presence of a speckle field in a coherent incoming wavefront [13][14][15][16][17][18][19]. The nonlinear response and the restricted dynamic range imaging capabilities of the SH sensor reduce the accuracy (indeed the possibility) of the reconstructed wavefront.…”

Section: Introductionmentioning

confidence: 99%

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Shack–Hartmann centroid detection method based on high dynamic range imaging and normalization techniques

et al. 2010

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In the optical quality measuring process of an optical system, including diamond-turning components, the use of a laser light source can produce an undesirable speckle effect in a Shack-Hartmann (SH) CCD sensor. This speckle noise can deteriorate the precision and accuracy of the wavefront sensor measurement. Here we present a SH centroid detection method founded on computer-based techniques and capable of measurement in the presence of strong speckle noise. The method extends the dynamic range imaging capabilities of the SH sensor through the use of a set of different CCD integration times. The resultant extended range spot map is normalized to accurately obtain the spot centroids. The proposed method has been applied to measure the optical quality of the main optical system (MOS) of the mid-infrared instrument telescope smulator. The wavefront at the exit of this optical system is affected by speckle noise when it is illuminated by a laser source and by air turbulence because it has a long back focal length (3017 mm). Using the proposed technique, the MOS wavefront error was measured and satisfactory results were obtained.

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Measurement of eye aberrations in a speckle field

Cited by 2 publications

References 0 publications

Benefit of higher closed�??loop bandwidths in ocular adaptive optics

Benefit of higher closed�??loop bandwidths in ocular adaptive optics

Shack–Hartmann centroid detection method based on high dynamic range imaging and normalization techniques

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