Microlens diffusers for efficient laser speckle generation

Ducharme, Alfred Dale

doi:10.1364/oe.15.014573

Cited by 16 publications

(10 citation statements)

References 8 publications

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“…Analysis of the sets of images collected in this SPIFI diffuser experiment exhibit statistics similar to other measurements of similar engineered diffusers [12]. Figure 3(a) displays a histogram of the retrieved values at each pixel of each directly retrieved image.…”

supporting

confidence: 61%

Two-dimensional spatial-frequency-modulated imaging through parallel acquisition of line images

2013

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This Letter demonstrates a two-dimensional imaging technique that uses a line scan camera to resolve one spatial dimension and temporal modulation to resolve the perpendicular dimension. A temporal intensity modulation, which increases linearly in frequency along one direction is applied to an illumination beam. The modulated light distribution is imaged onto an object then onto a line scan camera oriented perpendicularly to the direction of the modulation sweep. A line diffuser is placed shortly before the line scan camera and diffuses light along the direction of modulation so that each pixel collects all modulation frequencies.

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supporting

confidence: 61%

Two-dimensional spatial-frequency-modulated imaging through parallel acquisition of line images

2013

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“…Precisely, the output PSD corresponds to the ensemble averaged one-dimensional Fourier transforms of the horizontal rows in the image [22]:…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Investigation of a CCD modulation transfer function using the speckle method at different laser wavelengths and sub-windowing options

Nasibov

Kholmatov

Nasibov

et al. 2011

Int. J. Metrol. Qual. Eng.

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Abstract.We have experimentally investigated the MTF of a scientific grade CCD, especially considering its behavior induced by different laser wavelengths (from 470 nm to 633 nm) and varying number of total charge transfers. The MTF measurements were performed using laser speckles and utilizing the single-slit method. The MTF of the sensor was examined from zero to the Nyquist frequency. The results obtained at different wavelengths were compared. It was shown that the spectral behavior of the MTF is negligibly small; moreover the small variation is observed at the high frequency region. It was also observed that the variation of the total number of charge transfers, adjusted by size and location of the region of interest for readout pattern, is within the intrinsic error of the single-slit aperture laser speckle method.

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“…The HiLAM diffuser is a micro-lens highefficiency diffuser and was previously demonstrated as an excellent randomizer for the generation of laser speckle. 12,13 The spacing between the HiLAM diffuser and cross-aperture was 12mm. The output of the cross-aperture is passed through a linear polarizer to limit the output to a single laser speckle pattern.…”

Section: Demonstration Of Cross-aperture Mtf Measurementmentioning

confidence: 99%

Recent advances in the modulation transfer function testing of detector arrays

Ducharme

2008

SPIE Proceedings

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The increased complexity of imaging sensors and total number of discrete detector sites has challenged traditional testing methods. The importance of reliable modulation transfer function testing of imaging sensors with high uncertainty has consequently grown more difficult. In this paper we demonstrate the design of an aperture for the generation of laser speckle with a flat power spectrum covering a wide-band of the measurement spatial frequency range. This aperture allows for the measurement of modulation transfer function (MTF) from zero to twice the Nyquist frequency of a twodimensional detector array. This design mitigates many of the measurement issues inherent in other aperture designs. The MTF measurement of a charge-coupled device (CCD) detector array is used to demonstrate the measurement technique and illustrate the advantages of the new aperture design.

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Microlens diffusers for efficient laser speckle generation

Cited by 16 publications

References 8 publications

Two-dimensional spatial-frequency-modulated imaging through parallel acquisition of line images

Two-dimensional spatial-frequency-modulated imaging through parallel acquisition of line images

Investigation of a CCD modulation transfer function using the speckle method at different laser wavelengths and sub-windowing options

Recent advances in the modulation transfer function testing of detector arrays

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