Implementation problems in Hadamard transform spectrometry

Dyer, Ruth A.; Dyer, Stephen A.; Harms, B.K.; Johnson, T.W.; Park, J.B.

doi:10.1109/19.50437

Cited by 13 publications

(6 citation statements)

References 6 publications

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“…To this point, the treatment has assumed a perfect mask, optics, and sample such that the m ask is implemented without defect and the sample does not change during the course of measurement. If the mask has wavelength-dependent transmission or is imperfectly opaque, 13 has other imperfections, 19,20 the sample undergoes photobleaching, [21][22][23] or an optical arrangement is used that causes diffraction-limited spreading, 10 then the effective encoding is no longer by S. Rather, the encoding is by an unknown m atrix S* and errors arise when this matrix is decoded by S 2 1 . The theory, impact, and use of matrices other than S has been treated at some length in the literature and only a brief overview will be presented here.…”

Section: Effects Of Encoding Errors On Hadamard Transform System Smentioning

confidence: 99%

“…7,9,10 W hile the theory of mask effects has been treated quite extensively, a more limited literature exists documenting artifact-correcting procedures. [11][12][13][14] One problem of particular interest arises from a class of Hadamard systems that may exhibit echo artifacts even in the absence of errors in the mask itself. 9,10 The appearance of these artifacts depends on the length of the sequence, and information about the artifact-inducing phenomena can be inferred from the artifact behavior.…”

Section: Introductionmentioning

confidence: 99%

“…The relevant literature should be consulted for other types of masking effects. [11][12][13][14][15][16][17] An example of such a system was noted in the behavior of a confocal Hadamard transform spectroscopy system. 10 This system exhibited echoes due to diffractionlimited optical spreading in the presentation of the mask to a sample followed by detection through the same mask.…”

Section: Introductionmentioning

confidence: 99%

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Virtual Column Method for Correcting Masking Effects in Hadamard Transform Systems

Hanley

2003

Appl Spectrosc

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Section: Effects Of Encoding Errors On Hadamard Transform System Smentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Virtual Column Method for Correcting Masking Effects in Hadamard Transform Systems

Hanley

2003

Appl Spectrosc

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“…2. If the mask is imperfect, the theory of distorted S-m atrices, which are designated S*, must be considered in order to recover c. 11,[26][27][28][29][30][31] Transverse Line Spread Functions in Second-Order Hadamard Systems. Numerical calculations of wide eld uorescence point spread functions (PSF) have been treated previously.…”

Section: Th Eorymentioning

confidence: 99%

Highly Multiplexed Optically Sectioned Spectroscopic Imaging in a Programmable Array Microscope

Hanley

Jovin

2001

Appl Spectrosc

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We report the construction of a spectroscopic programmable array microscope capable of optical sectioning using H adamard transform methods. Previously described H adamard transform imaging consisted of rst-order systems in which the m ask was used for either illumination or detection. In this paper, a second-order Hadamard transform system is described in which a single one-dimensional mask serves for both illumination and detection. The system veri es earlier predictions that the optical spreading function along the transform axis can be inferred from the echoes arising in second-order systems using sequence lengths of 2 n -1. W ith a one-dimensional H adamard mask, the system has an axial resolution of 1.3 m m and may be used with or without the subtraction of an appropriately scaled wide eld image depending on the degree of sectioning required. The system was tested using thin lms, uorescent beads, and a xed biological specimen.

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“…The use of liquid cr ystals involves the problem of incomplete opacity of the blocked elements. 10 The use of AOTFs is still in the initial stages and, although the principles involved have been demonstrated, only seven wavelengths have thus far been m ultiplexed. 8 Also, it should be thoroughly investigated whether the multiplex gain is jeopardized by the decrease in light intensity resulting from the fact that AOTF systems operate with a limited power of radiofrequency signal applied to the piezoelectric transducer.…”

Section: Introductionmentioning

confidence: 99%

Dual-Beam Near-Infrared Hadamard Spectrophotometer

Silva

Pasquini

2001

Appl Spectrosc

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A dual-beam Hadamard multiplexed spectrophotometer is described. The instrument is intended to work in the near-infrared region of the electromagnetic spectrum (900–1800 nm) and is based on the use of a linear Hadamard mask containing 255 multiplexing elements. Simple symmetric Czerny–Turner optics were employed based on 10 cm diameter, 20 cm focus spherical mirrors and a plane grating containing 295 grooves mm−1. The dual-path system employs the multiplexed beam exiting from the mask, which can then be split by using either an integrating sphere, a bifurcated optical bundle, or a beamsplitter. Two cooled PbS or InAs detectors were employed to collect the 255 multiplexed intensities in about 8 s. Signal was obtained by linear displacement of the mask, which was controlled by software written in VisualBasic 4.0. Spectral data were demultiplexed with a program written in the same language. The instrument can successfully correct for the drift of the light source intensity. The wavelength precision is 0.4 nm, while the average standard deviation for absorbance measurements taken from 900 to 1800 nm is 1.5 × 10−3 absorbance units, a value that is about three times lower than that obtained for the single-beam multiplexed approach. The instrument has been applied to the determination of water in fuel ethanol with the use of partial least-squares modeling. The absolute standard error of prediction was 0.07% (w/w).

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Implementation problems in Hadamard transform spectrometry

Cited by 13 publications

References 6 publications

Virtual Column Method for Correcting Masking Effects in Hadamard Transform Systems

Virtual Column Method for Correcting Masking Effects in Hadamard Transform Systems

Highly Multiplexed Optically Sectioned Spectroscopic Imaging in a Programmable Array Microscope

Dual-Beam Near-Infrared Hadamard Spectrophotometer

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