Techniques to improve the flatness of reflective micro-optical arrays

Seunarine, K.; Calton, David; Underwood, Ian; Stevenson, J.T.M.; Gundlach, A.M.; Begbie, M.

doi:10.1016/s0924-4247(99)00199-5

Cited by 14 publications

(8 citation statements)

References 12 publications

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“…The backplane is manufactured at commercial VLSI foundries using standard CMOS methods and processes, which unfortunately are not optimized with optical performance in mind. In consequence, although the resulting devices can be made flat at the pixel level to prevent scattering and improve diffraction efficiency, they have bows and warps at the die level [34], which frequently gives rise to major optical aberrations.…”

Section: Modulator Aberrations and Correctionmentioning

confidence: 99%

Design strategies for optimizing holographic optical tweezers set-ups

Martı́n-Badosa¹,

Montes-Usategui²,

Carnicer³

et al. 2007

J. Opt. A: Pure Appl. Opt.

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Abstract. We provide a detailed account of the construction of a system of holographic optical tweezers. While a lot of information is available on the design, alignment and calibration of other optical trapping configurations, those based on holography are relatively poorly described. Inclusion of a spatial light modulator in the setup gives rise to particular design trade-offs and constraints, and the system benefits from specific optimization strategies, which we discuss.

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Section: Modulator Aberrations and Correctionmentioning

confidence: 99%

Design strategies for optimizing holographic optical tweezers set-ups

Martı́n-Badosa¹,

Montes-Usategui²,

Carnicer³

et al. 2007

J. Opt. A: Pure Appl. Opt.

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“…Unfortunately, the silicon backplane manufactured using standard CMOS methods is not flat [20], which frequently gives rise to important optical aberration. Such distortion is too strong to ignore when using SLMs for wavefront control in applications such as laser beam steering, diffractive optical element generation, or emulation of atmospheric turbulence.…”

Section: Introductionmentioning

confidence: 99%

Correction of aberration in holographic optical tweezers using a Shack-Hartmann sensor

2009

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Optical aberration due to the nonflatness of spatial light modulators used in holographic optical tweezers significantly deteriorates the quality of the trap and may easily prevent stable trapping of particles. We use a Shack-Hartmann sensor to measure the distorted wavefront at the modulator plane; the conjugate of this wavefront is then added to the holograms written into the display to counteract its own curvature and thus compensate the optical aberration of the system. For a Holoeye LC-R 2500 reflective device, flatness is improved from 0:8λ to λ=16 (λ ¼ 532 nm), leading to a diffraction-limited spot at the focal plane of the microscope objective, which makes stable trapping possible. This process could be fully automated in a closed-loop configuration and would eventually allow other sources of aberration in the optical setup to be corrected for.

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“…Optimisation of the ECR machine has achieved deposition uniformities of 1% over a 75 mm wafer which compares well to commercially available silica spacer particles which may have variations of 10%. However, it should be noted that the thickness of the photoresist and the spacer width affect the spacer height [4] and must be calibrated. 6.…”

Section: Examples Of Cmp Planarisation [4]mentioning

confidence: 99%

“…6. Backplane flattening and device assembly [4] When the wafer is diced the bow on individual chips can become quite severe (up to l.5um)). One of the prime causes of silica spacers fracturing and ploughing into soft aluminium is that during cell assembly the optically flat cover glass is pressed down on the device.…”

Section: Examples Of Cmp Planarisation [4]mentioning

confidence: 99%