Randomly Multiplexed Diffractive Lens and Axicon for Spatial and Spectral Imaging

Anand, Vijayakumar; Katkus, Tomas; Juodkazis, Saulius

doi:10.3390/mi11040437

Cited by 19 publications

(20 citation statements)

References 30 publications

(76 reference statements)

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“…(b) Applicability range: The technique can be implemented using a quasi-random array of pinholes which is easy to create for any band of the electromagnetic spectrum and therefore the technique can be extended easily to other non-visible bands of the electromagnetic spectrum such as Terahertz and Infrared radiations for industrial applications. (c) Calibration time: The method requires lesser calibration time compared to the earlier studies 30 , 34 as it is sufficient to record the point spread functions only at the axial and spectral boundaries involving four camera shots and all other point spread functions can be synthesized 40 . (d) Hyperspectral imaging and spectrometry: The technique is a natural spectrometer as it is possible to get the spectrum for every pixel of an image.…”

Section: Discussionmentioning

confidence: 99%

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Single shot multispectral multidimensional imaging using chaotic waves

Anand

Maksimovic

et al. 2020

Sci Rep

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Multispectral imaging technology is a valuable scientific tool for various applications in astronomy, remote sensing, molecular fingerprinting, and fluorescence imaging. In this study, we demonstrate a single camera shot, lensless, interferenceless, motionless, non-scanning, space, spectrum, and time resolved five-dimensional incoherent imaging technique using tailored chaotic waves with quasi-random intensity and phase distributions. Chaotic waves can distinctly encode spatial and spectral information of an object in single self-interference intensity distribution. In this study, a tailored chaotic wave with a nearly pure phase function and lowest correlation noise is generated using a quasi-random array of pinholes. A unique sequence of signal processing techniques is applied to extract all possible spatial and spectral channels with the least entropy. The depth-wavelength reciprocity is exploited to see colour from depth and depth from colour and the physics of beam propagation is exploited to see at one depth by calibrating at another.

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Section: Discussionmentioning

confidence: 99%

“…Besides, in 31 – 33 , a holographic optical set up is required with polarization multiplexing and phase shifting. Recently, a modified Fresnel incoherent correlation holography has been demonstrated for 4D imaging with a single camera shot 34 but requires extensive training in the beginning.…”

Section: Introductionmentioning

confidence: 99%

Single shot multispectral multidimensional imaging using chaotic waves

Anand

Maksimovic

et al. 2020

Sci Rep

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“…However, in [19], as the hologram reconstruction was converted into a pattern recognition problem, FINCH showed a higher axial resolution which is not a property of the earlier version of FINCH. In another recent study [22], where an axicon was used instead of a QPM to generate the hologram in FINCH, the higher focal depth and lower spectral sensitivity which are characteristics of a Bessel beam were not observed during the reconstruction [22]. These surprising aspects have not been investigated yet.…”

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confidence: 99%

“…The optical configuration of FINCH in polarization multiplexing scheme [8] and spatial random multiplexing scheme [1,19,22] are shown in Figs. 1(a) and 1(b) respectively.…”

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Review of Fresnel Incoherent Correlation Holography with Linear and Non-Linear Correlations

Anand¹,

Katkus²,

Ng³

et al. 2020

Preprint

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Fresnel incoherent correlation holography (FINCH) is a well-established incoherent imaging technique. In FINCH, three self-interference holograms are recorded with calculated phase differences between the two interfering, differently modulated object waves and projected into a complex hologram. The object is reconstructed without the twin image and bias terms by a numerical Fresnel back propagation of the complex hologram. A modified approach to implement FINCH by a single camera shot by pre-calibrating the system involving recording of the point spread function library and reconstruction by a non-linear cross-correlation has been introduced recently. The expression of the imaging characteristics from the modulation functions in original FINCH and the modified approach by pre-calibration in spatial and polarization multiplexing schemes are reviewed. The study reveals that a reconstructing function completely independent of the function of the phase mask is required for the faithful expression of the characteristics of the modulating function in the image reconstruction. In polarization multiplexing method by cross-correlation, a partial expression was observed, while in spatial multiplexing method by cross-correlation, the imaging characteristics converged towards a uniform behavior.

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Spatio‐Spectral‐Temporal Imaging of Fast Transient Phenomena Using a Random Array of Pinholes

Anand

Katkus

et al. 2020

Advanced Photonics Research

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Fast transient phenomena such as light–matter interactions, rapid electrical discharge, light scattering in tissues, and biochemical reactions that generate light signatures can be studied using high‐speed cameras. Herein, a lensless, single camera shot, spatio‐spectral‐temporal imaging technique based on chaotic waves is proposed and demonstrated. A random pinhole array is used as a chaotic wave generator to map every color point source in the object space to a unique random distribution. The spatio‐spectral signatures are recorded for two cases using a monochrome high‐speed camera, and an extensive library of spatio‐spectral signatures is synthesized by computational interpolation and extrapolation using the scaling factors of the Fresnel propagators. A spark generated by an abrupt electrical discharge is converted into a chaotic wave using the same pinhole array, and the hologram is recorded using the monochrome high‐speed camera in time. The recorded hologram of the spark is decomposed into spatio‐spectral 4D events in time with a temporal resolution of 40 μs using the semisynthetic spatio‐spectral signatures.

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Randomly Multiplexed Diffractive Lens and Axicon for Spatial and Spectral Imaging

Cited by 19 publications

References 30 publications

Single shot multispectral multidimensional imaging using chaotic waves

Single shot multispectral multidimensional imaging using chaotic waves

Review of Fresnel Incoherent Correlation Holography with Linear and Non-Linear Correlations

Spatio‐Spectral‐Temporal Imaging of Fast Transient Phenomena Using a Random Array of Pinholes

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