Characterization and correction of spherical aberration due to glass substrate in the design and fabrication of Fresnel zone lenses
TL;DR: Two novel schemes for correction of spherical aberration are proposed and studied and the accuracy of the proposed aberration correction schemes is validated.
Abstract: As with a conventional lens, a Fresnel zone lens (FZL) can be used to image objects at infinity or nearby In the latter case, the FZL converts a diverging spherical wavefront into a converging spherical wavefront The glass substrate on which the FZL is fabricated introduces spherical aberration resulting in a shift of the image plane and blurring of the image Two novel schemes for correction of this spherical aberration are proposed and studied in this paper To demonstrate them, FZLs are designed with and without aberration correction They are fabricated using electron beam direct writing The devices are evaluated and the accuracy of the proposed aberration correction schemes is validated
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TL;DR: In this paper, a random-like coded phase mask (CPM) is used to modulate light diffracted by a point object (pinhole) and the intensity pattern is recorded and composed as a point spread hologram (PSH).
Abstract: We present a lensless, interferenceless incoherent digital holography technique based on the principle of coded aperture correlation holography. The acquired digital hologram by this technique contains a three-dimensional image of some observed scene. Light diffracted by a point object (pinhole) is modulated using a random-like coded phase mask (CPM) and the intensity pattern is recorded and composed as a point spread hologram (PSH). A library of PSHs is created using the same CPM by moving the pinhole to all possible axial locations. Intensity diffracted through the same CPM from an object placed within the axial limits of the PSH library is recorded by a digital camera. The recorded intensity this time is composed as the object hologram. The image of the object at any axial plane is reconstructed by cross-correlating the object hologram with the corresponding component of the PSH library. The reconstruction noise attached to the image is suppressed by various methods. The reconstruction results of multiplane and thick objects by this technique are compared with regular lens-based imaging.
37 citations
TL;DR: In this paper, the authors used a randomly multiplexed bifocal binary diffractive Fresnel zone lenses fabricated using electron beam lithography for super-resolution 3D imaging.
Abstract: Fresnel incoherent correlation holography (FINCH) is a self-interference based super-resolution three-dimensional imaging technique. FINCH in inline configuration requires an active phase modulator to record at least three phase-shifted camera shots to reconstruct objects without twin image and bias terms. In this study, FINCH is realized using a randomly multiplexed bifocal binary diffractive Fresnel zone lenses fabricated using electron beam lithography. The object space is calibrated by axially scanning a point object along the optical axis and recording the corresponding point spread holograms (PSHs). An object is mounted within the calibrated object space, and the object hologram was recorded under identical experimental conditions used for recording the PSHs. The image of the object at different depths was reconstructed by a cross-correlation between the object hologram and the PSHs. Application potential including bio-medical optics is discussed.
34 citations
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TL;DR: The reconstruction results of multiplane and thick objects by this technique are compared with regular lens-based imaging.
Abstract: We present a lensless, interferenceless incoherent digital holography technique based on the principle of coded aperture correlation holography. The acquired digital hologram by this technique contains a three-dimensional image of some observed scene. Light diffracted by a point object is modulated using a random-like coded phase mask (CPM) and the intensity pattern is recorded and composed as a point spread hologram (PSH). A library of PSH is created using the same CPM by moving the pinhole to all possible axial locations. Intensity diffracted through the same CPM from an object placed within the axial limits of the PSH library is recorded by a digital camera. The recorded intensity this time is composed as the object hologram. The image of the object at any axial plane is reconstructed by cross-correlating the object hologram with the corresponding component of the PSH library. The reconstruction noise attached to the image is suppressed by various methods. The reconstruction results of multi-plane and thick objects by this technique are compared with regular lens-based imaging.
27 citations
TL;DR: This tutorial discusses one of the basic optical configurations of a lensless QPI technique based on the phase-retrieval algorithm andmented codes in Octave for image acquisition and automation using a web camera in an open source operating system are provided.
Abstract: Quantitative phase imaging (QPI) techniques are widely used for the label-free examining of transparent biological samples. QPI techniques can be broadly classified into interference-based and interferenceless methods. The interferometric methods which record the complex amplitude are usually bulky with many optical components and use coherent illumination. The interferenceless approaches which need only the intensity distribution and works using phase retrieval algorithms have gained attention as they require lesser resources, cost, space and can work with incoherent illumination. With rapid developments in computational optical techniques and deep learning, QPI has reached new levels of applications. In this tutorial, we discuss one of the basic optical configurations of a lensless QPI technique based on the phase-retrieval algorithm. Simulative studies on QPI of thin, thick, and greyscale phase objects with assistive pseudo-codes and computational codes in Octave is provided. Binary phase samples with positive and negative resist profiles were fabricated using lithography, and a single plane and two plane phase objects were constructed. Light diffracted from a point object is modulated by phase samples and the corresponding intensity patterns are recorded. The phase retrieval approach is applied for 2D and 3D phase reconstructions. Commented codes in Octave for image acquisition and automation using a web camera in an open source operating system are provided.
18 citations
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TL;DR: In this article, a modified hologram reconstruction mechanism is presented which introduces the single shot capability in Fresnel incoherent correlation holography (FINCH) in inline configuration requires an active phase modulator and at least three camera shots to reconstruct objects without the twin image and bias terms.
Abstract: Fresnel incoherent correlation holography (FINCH) is a self-interference based super-resolution three-dimensional imaging technique. FINCH in inline configuration requires an active phase modulator and at least three camera shots to reconstruct objects without the twin image and bias terms. In this study, FINCH is realized using a randomly multiplexed bifocal binary Fresnel zone lenses fabricated using electron beam lithography. A modified hologram reconstruction mechanism is presented which introduces the single shot capability in FINCH. A point spread hologram library was recorded using a point object located at different axial locations and an object hologram was recorded. The image of the object at different planes were reconstructed using decorrelation of the object hologram by the point spread hologram library. Application potential including bio-medical optics is discussed.
17 citations
Cites background from "Characterization and correction of ..."
...Earlier studies indicated that the exclusion of the thickness and refractive index of glass plates introduces substantial spherical aberration into the system resulting in a variation in the focal distances and blurring of the focal spot.(19) Two techniques have been proposed to avoid the spherical aberration....
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...The second Fresnel zone lens (FZL2) is designed for finite conjugate mode with u = z1 and v = z2/2.(19) The object wave is focused by FZL2 at z2/2 from the RMBDL....
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References
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TL;DR: In this article, phase-shifted Fresnel zone lenses (FZLs) were used for THz wave generation by mixing optical beams from integrated twin lasers on GaAs photomixers.
Abstract: Novel optics configurations simplified by using phase-shifted Fresnel zone lenses (FZLs) are proposed for THz wave generation by mixing optical beams from integrated twin lasers on GaAs photomixers. The phase-shifted FZL superimposes and collinearly collimates the beams from the closely-aligned twin lasers, or superimposes and focuses them directly onto a photomixer, with a high efficiency. Phase-shifted binary and analog FZLs were designed and fabricated by electron beam writing. Good performances close to the theoretical prediction were obtained, and THz wave generation was successfully demonstrated.
4 citations
"Characterization and correction of ..." refers methods in this paper
...In order to avoid this additional collimating lens, FZLs could be used in the u–v configuration instead [14,15]....
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29 Dec 2010
TL;DR: Fractal zone plates and optical pin sieves are designed and their focusing properties are analyzed using scalar diffraction formula in this paper, it is found that these zone plates offer better control on beam parameters compared to Fresnel Zone plates.
Abstract: Fractal Zone plates and optical pin sieves are designed and their focusing properties are analyzed using scalar diffraction formula. It is found that these zone plates offer better control on beam parameters compared to Fresnel Zone plates. These zone plates are then fabricated on to quartz substrates using UV lithography and the results are confirmed.
1 citations
"Characterization and correction of ..." refers methods in this paper
...FZLs can be fabricated by different techniques, such as photolithography [12], electron beam direct writing [15], and focused ion beammilling [22]....
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...In most of the earlier reported situations, the FZLs were designed for converting a plane wavefront into a converging spherical wavefront (f configuration) [8–12]....
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