Diffractive lens in 8- to 10-μm forward-looking infrared system

Kudo, J.; Wada, Hideo; Okamura, Toshihiro; Kobayashi, Masako; Tanikawa, Kunihiro

doi:10.1117/1.1487365

Cited by 14 publications

(3 citation statements)

References 2 publications

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“…The infrared lens is a critical component in long-wave infrared imaging systems, which takes an important role in the field of environmental monitoring [1], medical diagnosis [2], and industrial process control [3]. A traditional infrared lens realizes the focusing function by its thickness and continuous shaping profiles.…”

Section: Introductionmentioning

confidence: 99%

Design of an all-silicon long-wave infrared meta spiral zone plate

Hao

Wang

et al. 2023

Ninth Symposium on Novel Photoelectronic Detection Technology and Applications

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Traditional infrared lenses cannot meet the requirements of planarization and lightweight of infrared optical systems due to their large volume and mass. An infrared metasurface with almost zero thickness can control the incident beam’s amplitude, phase and polarization arbitrarily, which make it possible to circumvent these limitations. However, no metasurface has been designed to realize sub-diffraction focusing in the long-wave infrared band. In this article, a longwave infrared meta spiral zone plate (LWIR-MSZP) is designed, which converts the incident linearly polarized beam to an azimuthally polarized beam and focuses the latter into a sub-diffraction solid spot. The designed LWIR-MSZP works at a wavelength of 10.6 μm and has a diameter of 480 μm and numerical aperture (NA) of 0.8. The simulated full width at half maximum (FWHM) and depth of focus (DOF) of the focal spot are 0.6λ and 2.24λ, respectively. The simulated efficiency is 24.04%. The proposed design procedure greatly simplifies the long-wave infrared sub-diffractive focusing optical system and complements the technical gap to achieve sub-diffractive focusing in long-wave infrared using a metasurface. To make it further, the all-silicon meta-atom employed in this work has the advantage of low cost once semiconductor fabrication techniques are introduced. We believe that this result can be applied to the related fields of super-resolution imaging and laser processing in long-wave infrared band.

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Section: Introductionmentioning

confidence: 99%

Design of an all-silicon long-wave infrared meta spiral zone plate

Hao

Wang

et al. 2023

Ninth Symposium on Novel Photoelectronic Detection Technology and Applications

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show abstract

“…In the field of environmental monitoring [1], imaging guidance [2], and industrial process control [3], the long-wavelength infrared imaging is important. The infrared lens is critical component in a long-wavelength infrared imaging system.…”

Section: Introductionmentioning

confidence: 99%

Simulation for multiwavelength large-aperture all-silicon metalenses in long-wave infrared

Hao

et al. 2022

Nanotechnology

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Long-wave infrared imaging systems are widely used in the field of environmental monitoring and imaging guidance. As the core components, the long-wave infrared lenses suffer the conditions of less available materials, difficult processing, large volume and mass. Metalens composed of sub-wavelength structures is one of the most potential candidates to achieve a lightweight and planar optical imaging systems. Meanwhile, it is essential to obtain large-aperture infrared lenses with high power and high resolution. However, it is difficult to use the finite-difference time-domain method to simulate a large-aperture metalens with the diameter of 201 mm due to the large amount of computational memory and computational time required. Here, to solve the mentioned problem, we firstly propose a simulation method for designing a large-aperture metalens, which combines the finite-difference time-domain algorithm and diffraction integration. The finite-difference time-domain algorithm is used to simulate the meta-atom’s transmitted complex amplitude and the one-dimensional simplification of the diffraction integral is to calculate the focused field distributions of the designed metalens. Furthermore, the meta-atom spatial multiplexing is applied to design the all-silicon metalenses with the aperture of 201 mm to realize dual-wavelength (10 μm and 11 μm) achromatic focusing, super anomalous dispersion focusing and super normal dispersion focusing. The designed metalenses are numerically confirmed, which reveal the feasibility of all-silicon sub-wavelength structures to accomplish the multiwavelength dispersion control. The designed all-silicon metalenses have the advantage of lightweight and compact. The proposed method is effective for the development of large-aperture imaging systems in the long-wave infrared.

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“…Thermal imaging technology, both midwave infrared (MWIR, wavelength from 3 to 5 μm) and longwave infrared (LWIR, wavelength from 8 to 12 μm) spectra have been extensively discussed in numerous studies over the past few decades. [1][2][3][4] Their applications cover a wide range of different fields, such as for industrial temperature measurement, noninvasive medical inspection, military stealth surveillance, and security biometrics recognition. Visual processing of these thermal images is commonly accomplished by utilizing the intensity threshold algorithm in which the intensities of the target pixels are compared with those of the background.…”

Section: Introductionmentioning

confidence: 99%

Achromatic triplet and athermalized lens assembly for both midwave and longwave infrared spectra

Kuo

2013

Opt. Eng

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Analytic solutions for finding the achromatic triplet in the midwave and longwave infrared spectra simultaneously are explored. The relationship between the combination of promising refractive materials and the system's optical power is also formulated. The principles for stabilizing the effective focal length of an air-spaced lens group with respect to temperature are explored, and the thermal properties of the optical component and mechanical elements mutually counterbalanced. An optical design based on these achromatic and athermal theories is demonstrated, and the image quality of the lens assembly seems to approach the diffractive limitation. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Diffractive lens in 8- to 10-μm forward-looking infrared system

Cited by 14 publications

References 2 publications

Design of an all-silicon long-wave infrared meta spiral zone plate

Design of an all-silicon long-wave infrared meta spiral zone plate

Simulation for multiwavelength large-aperture all-silicon metalenses in long-wave infrared

Achromatic triplet and athermalized lens assembly for both midwave and longwave infrared spectra

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