Optical testing using Shack-Hartmann wavefront sensors

Greivenkamp, John E.; Smith, Daniel G.; Gappinger, Robert O.; Williby, Gregory A.

doi:10.1117/12.427063

Cited by 18 publications

(12 citation statements)

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“…For many years there has been a special interest in measuring the quality of optical systems [1,2]. Although a large number of techniques are available for optical testing, interferometry [3] and wavefront sensing techniques [4][5][6][7] have been used extensively. The former include interferometric methods such Michelson, Fizeau, Mach-Zehnder, point-diffraction and shearing, and holographic techniques, among others.…”

Section: Introductionmentioning

confidence: 99%

Wavefront measurements of phase plates combining a point-diffraction interferometer and a Hartmann-Shack sensor

et al. 2010

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A dual setup composed of a point diffraction interferometer (PDI) and a Hartmann-Shack (HS) wavefront sensor was built to compare the estimates of wavefront aberrations provided by the two different and complementary techniques when applied to different phase plates. Results show that under the same experimental and fitting conditions both techniques provide similar information concerning the wavefront aberration map. When taking into account all Zernike terms up to 6th order, the maximum difference in root-mean-square wavefront error was 0.08 microm, and this reduced up to 0.03 microm when excluding lower-order terms. The effects of the pupil size and the order of the Zernike expansion used to reconstruct the wavefront were evaluated. The combination of the two techniques can accurately measure complicated phase profiles, combining the robustness of the HS and the higher resolution and dynamic range of the PDI.

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Section: Introductionmentioning

confidence: 99%

Wavefront measurements of phase plates combining a point-diffraction interferometer and a Hartmann-Shack sensor

et al. 2010

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“…There, however, is a tradeoff between dynamic range and sensitivity according to the number of microlenses and the focal length [11]. A small-size, long-focal-length MLA could increase the measurement accuracy associated with Equation (5) [8].…”

Section: Wavefront Sensor Computing Algorithm and Measurement Resultsmentioning

confidence: 99%

An Optical Wavefront Sensor Based on a Double Layer Microlens Array

Lin

Wei

Hsieh

et al. 2011

Sensors

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In order to determine light aberrations, Shack-Hartmann optical wavefront sensors make use of microlens arrays (MLA) to divide the incident light into small parts and focus them onto image planes. In this paper, we present the design and fabrication of long focal length MLA with various shapes and arrangements based on a double layer structure for optical wavefront sensing applications. A longer focal length MLA could provide high sensitivity in determining the average slope across each microlens under a given wavefront, and spatial resolution of a wavefront sensor is increased by numbers of microlenses across a detector. In order to extend focal length, we used polydimethysiloxane (PDMS) above MLA on a glass substrate. Because of small refractive index difference between PDMS and MLA interface (UV-resin), the incident light is less refracted and focused in further distance. Other specific focal lengths could also be realized by modifying the refractive index difference without changing the MLA size. Thus, the wavefront sensor could be improved with better sensitivity and higher spatial resolution.

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“…Table 1 shows the comparison of wavefront measurement results between commercial SHWFS and our SHWFS. There is a tradeoff between dynamic range and sensitivity according to the number of lenslets and the focal length [6]. A small-size, long-focal-length MLA could increase the measurement accuracy associated with equation (3) [3].…”

Section: Wavefront Measurement and Discussionmentioning

confidence: 99%

Shack-Hartmann wavefront sensor with high sensitivity by using long focal length microlens array

Lin

Wei

2011

SPIE Proceedings

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The performance of Shack-Hartmann wavefront sensor (SHWFS) is mainly described by the accuracy, spatial resolution, dynamic range, and sensitivity of the measurement. These factors are particularly affected by the design of the microlens array (MLA). In order to provide a large dynamic range of wavefront measurement, most of the conventional and commercial SHWFS implemented a short focal length lenslet array, which means that the measurement sensitivity is being sacrificed and the accuracy of the wavefront sensor will be degraded. However, it is also critical to detect very small displacement of SHWFS spot in order to reconstruct it into a fine wavefront variation. We fabricated long focal length MLA with various structure arrangement by thermal reflow process with Polydimethysiloxane (PDMS) cover on the glass substrate and implemented them on the image system. A longer focal length will provide high sensitivity in determining the average slope across each lenslet under a given wavefront, and the spatial resolution of the wavefront sensor is increased by the number of lenslets across the detector. The experimental setup consists of the fabricated 245 μm diameter MLA which provides a 5.2 mm long focal distance and is paired with the CMOS as the detector. The observable smallest sensitivity is around wavelength/20 (λ=630nm).

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Optical testing using Shack-Hartmann wavefront sensors

Cited by 18 publications

References 0 publications

Wavefront measurements of phase plates combining a point-diffraction interferometer and a Hartmann-Shack sensor

Wavefront measurements of phase plates combining a point-diffraction interferometer and a Hartmann-Shack sensor

An Optical Wavefront Sensor Based on a Double Layer Microlens Array

Shack-Hartmann wavefront sensor with high sensitivity by using long focal length microlens array

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