Super-resolution imaging for sub-IR frequencies based on total internal reflection

Barr, Lauren E.; Karlsen, Peter; Hornett, Samuel M.; Hooper, Ian R.; Mrnka, Michal; Lawrence, Christopher R.; Phillips, David B.; Hendry, Euan

doi:10.1364/optica.408678

Cited by 13 publications

(10 citation statements)

References 42 publications

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“…Another application demonstrated a TIR geometry in a near-field imaging system, in which a spatial modulator was formed by combining a light-sensitive silicon wafer with a prism. This unique combination allowed images of the sample structure to be reconstructed with a subwavelength lateral resolution [ 39 ]. The application of TIR combined with Light-Emitting Diodes (LEDs) effectively enhances the efficiency of light energy, which utilizes the evanescent wave in a TIR setup coupled with a conductive interface [ 40 ].…”

Section: Introductionmentioning

confidence: 99%

Novel Bilayer Micropyramid Structure Photonic Nanojet for Enhancing a Focused Optical Field

Liu

Zhang

et al. 2021

Nanomaterials

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In this paper, synthetically using refraction, diffraction, and interference effects to achieve free manipulation of the focused optical field, we firstly present a photonic nanojet (PNJ) generated by a micropyramid, which is combined with multilayer thin films. The theory of total internal reflection (TIR) was creatively used to design the base angle of the micropyramid, and the size parameters and material properties of the microstructure were deduced via the expected optical field distribution. The as-designed bilayer micropyramid array was fabricated by using the single-point diamond turning (SPDT) technique, nanoimprint lithography (NIL), and proportional inductively coupled plasma (ICP) etching. After the investigation, the results of optical field measurement were highly consistent with those of the numerical simulation, and they were both within the theoretical calculation range. The bilayer micropyramid array PNJ enhanced the interference effect of incident and scattered fields; thus, the intensity of the focused light field reached 33.8-times that of the initial light, and the range of the focused light field was extended to 10.08λ. Moreover, the full width at half maximum (FWHM) of the focal spot achieved was 0.6λ, which was close to the diffraction limit.

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Section: Introductionmentioning

confidence: 99%

Novel Bilayer Micropyramid Structure Photonic Nanojet for Enhancing a Focused Optical Field

Liu

Zhang

et al. 2021

Nanomaterials

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“…This requirement for free-space propagation places limits on the minimum operational volume of a wide range of optical elements and devices, such as cameras, microscopes, telescopes and spectrometers. The issue of size becomes even more prominent at longer wavelengths in so-called quasi-optical systems common to the terahertz [1], millimetre-wave [2] and microwave domains [3]. In this regime, free-space diffraction is fundamental to the operation of antennas [4][5][6][7] and beam waveguides [8], and this can lead to very large optical systems [9].…”

Section: Introductionmentioning

confidence: 99%

Space-squeezing optics in the microwave spectral region

Mrnka¹,

Hendry²,

Láčík³

et al. 2021

Preprint

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Optical systems often consist largely of empty space, as diffraction effects that occur through free-space propagation can be crucial to their function. Contracting these voids offers a path to the miniaturisation of a wide range of optical devices. Recently, a new optical element -coined a 'spaceplate' -has been proposed, that is capable of emulating the effects of diffraction over a specified propagation distance using a thinner non-local metamaterial [Nat. Commun. 12, 3512 (2021)]. The compression factor of such an element is given by the ratio of the length of free-space that is replaced to the thickness of the spaceplate itself. In this work we test a prototype spaceplate in the microwave spectral region (17-18 GHz) -the first such demonstration designed to operate in ambient air. Our device consists of a Fabry-Pérot cavity formed from two perforated conductive sheets, with a compression factor that can be directly tuned by varying the size of the perforations. Using a pair of directive horn antennas, we show evidence for a compression factor of up to ∼6.6. We also observe some distortion to the transmitted field, and we discuss future improvements to minimise aberrations. Finally, we investigate the fundamental trade-offs that exist between the compression factor, transmission efficiency, numerical aperture (NA) and bandwidth of this single resonator spaceplate design, and highlight that it can reach arbitrarily high compression factors by restricting its NA and bandwidth.

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“…Single-pixel THz cameras do exist 10,11 and they have been used for inspection of circuits hidden behind semiconductors, 12 for example, as well as for near-field THz imaging of solid state systems 13−16 and biological samples as well. 17 There have also been studies showing 2D tomographic imaging 18 and potential for standoff applications. 19 Previously, we showed that a THz video can be obtained and displayed in real-time with a single-pixel THz camera.…”

mentioning

confidence: 99%

“…This makes them highly suited for THz imaging. Single-pixel THz cameras do exist , and they have been used for inspection of circuits hidden behind semiconductors, for example, as well as for near-field THz imaging of solid state systems − and biological samples as well . There have also been studies showing 2D tomographic imaging and potential for standoff applications .…”

mentioning

confidence: 99%

“…The most interesting aspect of this work is that there is no inherently expensive equipment involved, and the potential of achieving faster acquisition is restricted by noise and not equipment capabilities. Given the large range of possible applications of single-pixel THz cameras, ,,− future work will need to focus on optical designs for more specific applications, such as skin imaging or semiconductor quality control.…”

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confidence: 99%

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Rapid Imaging of Pulsed Terahertz Radiation with Spatial Light Modulators and Neural Networks

Stantchev

Pickwell‐MacPherson

2021

ACS Photonics

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We report the first use of a convolutional neural network for terahertz (THz) imaging combined with a single-pixel camera to achieve high quality hyperspectral THz imaging 10× faster than the current commercial systems, with faster potential only limited by noise. Imaging with a spatial light modulator (SLM) relies on projecting a set of spatial patterns onto an object and recording the transmission with a single-pixel detector, and an optical delay unit (ODU) is used to obtain the terahertz time-of-flight information. A key breakthrough in this work is to synchronize the equipment to not need any time to instruct the ODU to move while projecting the patterns.

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Super-resolution imaging for sub-IR frequencies based on total internal reflection

Cited by 13 publications

References 42 publications

Novel Bilayer Micropyramid Structure Photonic Nanojet for Enhancing a Focused Optical Field

Novel Bilayer Micropyramid Structure Photonic Nanojet for Enhancing a Focused Optical Field

Space-squeezing optics in the microwave spectral region

Rapid Imaging of Pulsed Terahertz Radiation with Spatial Light Modulators and Neural Networks

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