Implementation of a Large-Area Diffractive Lens Using Multiple Sub-Aperture Diffractive Lenses and Computational Reconstruction

Gopinath, Shivasubramanian; Angamuthu, Praveen Periysamy; Kahro, Tauno; Bleahu, Andrei; Arockiaraj, Francis Gracy; Smith, Daniel; Ng, Soon Hock; Juodkazis, Saulius; Kukli, Kaupo; Tamm, Aile; Anand, Vijayakumar

doi:10.3390/photonics10010003

Cited by 17 publications

(15 citation statements)

References 49 publications

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“…An optical experiment was carried out with a laboratory model of telescope. 28 A spatially incoherent light source (Thorlabs, 170 mW, λ = 650 nm and Δλ = 20 nm) was used for illumination of objects. A 10 μm pinhole was used for recording the PSF and an USAF object (Group -5, Element 1) number 5 and gratings with a line width of 15.63 μm was used as the test object.…”

Section: Methodsmentioning

confidence: 99%

Realizing large-area diffractive lens using multiple subaperture diffractive lenses and computational reconstruction

Gopinath,

Ignatius Xavier,

Periyasamy Angamuthu

et al. 2023

Holography: Advances and Modern Trends VIII

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Manufacturing large area diffractive lenses (DLs) is a challenging task, as in many cases, the outermost zone width surpasses the photolithography limit and even the wavelength limit. In this study, a computational imaging method is proposed which allows realizing a single large area strong DL with multiple sub-aperture weak DLs. The sub-aperture DLs collect light and focus it into multiple points within the area of the image sensor instead of a single point which increases the width of the zones of the DL. A computational reconstruction method was applied to reconstruct a highresolution image from the multiple low-resolution images.

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Section: Methodsmentioning

confidence: 99%

Realizing large-area diffractive lens using multiple subaperture diffractive lenses and computational reconstruction

Gopinath,

Ignatius Xavier,

Periyasamy Angamuthu

et al. 2023

Holography: Advances and Modern Trends VIII

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“…A positive photoresist (AR-P 3510T, Allresist) was spin coated on the substrate at 4000 rpm for 60 s, followed by a soft bake on a hot plate at 100 o C for 60 s. A Maskless Aligner (Heidelberg Instruments µMLA) with precise dose control of the light source λ = 390 nm was used for photoresist exposure. After exposure to UV light, the mask was developed in AR 300-44 (Allresist) and rinsed in ultrapure water [38]. The duration of exposure for a single mask is ~1 hr.…”

Section: Preliminary Experiments With Diffractive Optical Elements Fa...mentioning

confidence: 99%

3D Incoherent Imaging Using an Ensemble of Sparse Self-Rotating Beams

Anand¹,

Bleahu²,

gopinath³

et al. 2023

Preprint

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Interferenceless coded aperture correlation holography (I-COACH) is one of the simplest incoherent holography techniques. In I-COACH, the light from an object is modulated by a coded mask, and the resulting intensity distribution is recorded. The 3D image of the object is reconstructed by processing the object intensity distribution with the pre-recorded 3D point spread intensity distributions. The first version of I-COACH was implemented using a scattering phase mask, which makes its implementation challenging in light-sensitive experiments. The I-COACH technique gradually evolved with the advancement in the engineering of coded phase masks that retain randomness but improve the concentration of light in smaller areas in the image sensor. In this direction, I-COACH was demonstrated using weakly scattered intensity patterns, dot patterns and recently using accelerating Airy patterns, and the case with accelerating Airy patterns exhibited the highest SNR. In this study, we propose and demonstrate I-COACH with an ensemble of self-rotating beams. Unlike accelerating Airy beams, self-rotating beams exhibit a better energy concentration. In the case of self-rotating beams, the uniqueness of the intensity distributions with depth is attributed to the rotation of the intensity pattern as opposed to the shifts of the Airy patterns, making the intensity distribution stable along depths. A significant improvement in SNR was observed in optical experiments.

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“…26 The performance of LRRA was found to be better than NLR and LRA when implementing deterministic optical fields. 27,28,29 Recently, several methods were reported to tune AR independent of LR using Bessel, Airy and self-rotating beams. 30,31,32 In this study, we proposed and demonstrated two hybridization methods HM-1 and HM-2 for engineering AR independent of LR both in real time and post recording.…”

Section: Introductionmentioning

confidence: 99%

Engineering axial resolution realtime and postrecording of incoherent holograms using hybridization techniques

Gopinath,

John Francis Rajeswary,

Anand

2024

International Conference on Optical and Photonic Engineering (icOPEN 2023)

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In incoherent digital holography (IDH) and in any imaging technique, the lateral and axial resolutions are intertwined and consequently changing one characteristic affects the other. In this study, we present two new hybridization techniques HM-1, and HM-2 for IDH, one for real-time and another for post-recording of holograms respectively, to engineer the axial resolution independent of lateral resolution. Two optical functions namely a lens and an axicon, with a low focal depth and a high focal depth respectively are considered. In both hybridization techniques, the axial resolution can be tuned between the limits of the axial resolutions of lens and axicon, while maintaining a constant lateral resolution. In HM-1, the axial resolution was engineered using a special phase mask designed using a modified version of Gerchberg-Saxton algorithm that can generate a spherical beam and Bessel beam for every object point and create self-interference between them. By controlling the strengths of the two beams, the axial resolution can be tuned without changing the lateral resolution. This method requires an active optical device such as a spatial light modulator. HM-2 involves two recordings of the same scene, one with a lens and another with an axicon which are then combined after recording. By controlling the weights of the two recordings, the axial resolution can be tuned between the limits of lens and the axicon independent of lateral resolution. In this case, passive diffractive or refractive optical elements are sufficient. Both hybridization techniques are implemented in indirect imaging mode consisting of three steps: recording point spread hologram, object hologram and reconstruction by Lucy-Richardson-Rosen algorithm.

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Implementation of a Large-Area Diffractive Lens Using Multiple Sub-Aperture Diffractive Lenses and Computational Reconstruction

Cited by 17 publications

References 49 publications

Realizing large-area diffractive lens using multiple subaperture diffractive lenses and computational reconstruction

Realizing large-area diffractive lens using multiple subaperture diffractive lenses and computational reconstruction

3D Incoherent Imaging Using an Ensemble of Sparse Self-Rotating Beams

Engineering axial resolution realtime and postrecording of incoherent holograms using hybridization techniques

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