Ultra-compact micro-optical system for multispectral imaging

Hubold, Martin; Berlich, R.; Gassner, Christin; Brüning, Robert; Brunner, Róbert

doi:10.1117/12.2295343

Cited by 7 publications

(4 citation statements)

References 8 publications

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“…Equation (6) gives the final form of multispectral light-field acquisition, which is also the core of multispectral light-field reconstruction in the proposed system. The idea of least squares is used to determine the spectral response by minimizing the sum of squares of the objective function, realizing the decoupling reconstruction of the multispectral light field, and finally obtaining the multispectral light-field characteristics of the scene [44] ŝ ¼ arg min…”

Section: Spectral Reconstruction Based On Convex Optimization Theorymentioning

confidence: 99%

“…The Fourier transform of the interferogram is then used to obtain the target spectrum. [ 4 ] Binary optical lenses are also employed for dispersion, [ 5,6 ] while filters are an optical thin‐film technology that is one of the most common dispersion methods. [ 7 ] Dispersive types provide high accuracy but poor imaging quality, while filtering types offer relatively high imaging quality and suffer from inconsistencies in image overlap.…”

Section: Introductionmentioning

confidence: 99%

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Snapshot Multispectral Light‐Field Imaging Based on Nematic Liquid‐Crystal Microlens Array via Deep Learning

Li,

Chen

et al. 2023

Adv Eng Mater

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In this study, we have developed a multispectral light field imaging system using nematic liquid crystal microlens arrays (LC‐MLAs). The system solves the spectral under‐sampling and complex system issues in existing light field and spectral cameras. The LC‐MLA is the core optical element of the snapshot imaging system. No dispersion or customized scanning machinery is required to obtain multispectral light fields. Deep learning technology is utilized to reconstruct spectral information from raw data. Experiments demonstrate that the proposed method efficiently reconstructs multispectral data with 10nm accuracy in the visible wavelength range of [400nm, 700nm]. The system offers high precision, simple equipment, and relatively low cost without additional dispersion and filtering devices.This article is protected by copyright. All rights reserved.

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Section: Spectral Reconstruction Based On Convex Optimization Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Snapshot Multispectral Light‐Field Imaging Based on Nematic Liquid‐Crystal Microlens Array via Deep Learning

Li,

Chen

et al. 2023

Adv Eng Mater

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“…Another way to implement snapshot imagers is by means of a lenslet array, which in combination with a filter array inserted in front of the lenslet array or image sensor allows to duplicate and project the image of each lenslet on the corresponding area of the sensor. One example is shown in [14] where a Continuous Variable Filter (CVF) of Delta Film is used together with a microlens array to provide simultaneous snapshot acquisition of 66 bands in the VNIR range (450-880 nm) with a spatial resolution of 400x400 pixels per band. Finally, we can implement a snapshot system by using Multi-Spectral Filter Arrays (MSFA) that integrate multiple filter elements in a mosaic pattern.…”

Section: Introductionmentioning

confidence: 99%

Compact high-speed snapshot multispectral imagers in the VIS/NIR (460 to 960 nm) and SWIR range (1.1 to 1.65 nm) and its potential in a diverse range of applications

Blanch-Perez-del-Notario¹,

Geelen²,

Li³

et al. 2023

Hyperspectral Imaging and Applications II

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This paper presents the latest advances on Imec snapshot multispectral imagers based on either 3x3, 4x4 and 5x5 mosaic filter patterning on industry ready VIS/NIR and SWIR detectors. The mosaic patterns are implemented by means of high-transmission Fabry-Pérot interferometers processed using thin-film technology. Our snapshot multispectral imagers offer a spatial resolution of 640x480 pixels (SWIR) and 2048x1088 (VIS/NIR) down sampled according to the mosaic pattern to acquire data in 9 (3x3), 16 (4x4) of 25 (5x5) spectral bands respectively. To achieve imaging at the native spatial resolution of the sensor, super resolution methods are available post-acquisition. Moreover, our compact USB-3 cameras of 260 gr (SWIR) and 27 gr (VNIR), without lens, reach an acquisition speed of up to 120 multispectral cubes/second and are therefore suitable for dynamic applications, high-speed inspection such as a conveyor belt or UAV inspection. The potential for snapshot cameras in a wide range of applications is showcased in this paper. We first show how applications on industrial quality inspection (chocolate gloss estimation) and precision agriculture (plant disease detection) achieve good discrimination potential in the VNIR range. Specifically, UAV inspection benefits from our compact camera size, low weight, and video capabilities. We then demonstrate the potential for plastic and textile recycling in the SWIR range and the benefit brought by both VNIR and SWIR ranges for people tracking under low visibility conditions. Finally, an application involving the joint use of a microscope and a multispectral camera system is presented for particle contamination exposure assessment. The suitable range is in this case application dependent.

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“…The lack of scanning artifacts and a remarkable compactness 5 represent the major advantage of respective systems. An ultra-compact realization of such a snapshot system was realized using a micro-optical, multi-aperture system approach combined with a slanted linear variable spectral filter 6 . Here, we detail the required calibration procedure, which is customized to the multi-aperture imaging approach and the filter based wavelength separation.…”

Section: Introductionmentioning

confidence: 99%

System calibration and characterization of an ultra-compact multispectral snapshot imaging system

Hubold¹,

Berlich²,

Brüning³

et al. 2019

Photonics and Education in Measurement Science 2019

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In this work, we present a calibration procedure of a multispectral snapshot camera, which is based on a multi-aperture system approach combined with a slanted linear variable spectral filter. The ultra-compact multispectral imaging system exploits state of the art micro-optical manufacturing techniques on wafer-level, which leads to a size of only 60 x 60 x 28 mm 3. The setup enables the single-shot acquisition of 66 spectral channels with a linear spectral sampling over an extended wavelength range of 450-850 nm and a spatial sampling of 400x400 pixels per channel at a large field of view of 68°. In particular, we propose a spectral and spatial calibration procedure in order to extract hyperspectral data cubes from the acquired raw image and further, to analyze characteristic system parameters. Finally, we demonstrate the systems capabilities for advanced object classification using characteristic spectral indices by utilizing a customized multispectral analysis.

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Ultra-compact micro-optical system for multispectral imaging

Cited by 7 publications

References 8 publications

Snapshot Multispectral Light‐Field Imaging Based on Nematic Liquid‐Crystal Microlens Array via Deep Learning

Snapshot Multispectral Light‐Field Imaging Based on Nematic Liquid‐Crystal Microlens Array via Deep Learning

Compact high-speed snapshot multispectral imagers in the VIS/NIR (460 to 960 nm) and SWIR range (1.1 to 1.65 nm) and its potential in a diverse range of applications

System calibration and characterization of an ultra-compact multispectral snapshot imaging system

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