Detailed characterization of a hyperspectral snapshot imager for full-field chromatic confocal microscopy

Hahn, Robin; Haist, Tobias; Hämmerling, Freya-Elin; Fleischle, David; Schwanke, Oliver; Hauler, Otto; Rebner, Karsten; Brecht, Marc

doi:10.1117/12.2556797

Cited by 7 publications

(8 citation statements)

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“…In addition, the bandwidth (Full-Width at Half Maximum) of the filter more than doubles from 7 nm to 17 nm. Recently, similar result were independently observed by Hann et al [30].…”

Section: Experimental Validation Using the Equivalent Monolayer Modelsupporting

confidence: 86%

Pixel-integrated thin-film filter simulation and scaling trade-offs

Goossens

2021

Preprint

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Thin-film optical filters can nowadays be integrated onto pixels of commercial image sensors used for spectral imaging. A drawback of having more filters on an image sensor is a loss in spatial resolution which could be regained by using smaller pixels. However, this work shows that miniaturization causes a reduction in transmittance and requires a trade-off between pixel size and filter bandwidth. This is caused by diffraction and the reduced number of reflections in the filter. Analytical wave and ray optics models are developed and used for fast transmittance prediction and this is validated using a commercial spectral sensor and numerical simulations. The identified trade-off is an intrinsic limitation of pixel-integrated thin-film filter technology and the developed models will be useful tools for exploring new hardware and computational solutions.

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“…In addition, the bandwidth (Full-Width at Half Maximum) of the filter more than doubles from 7 nm to 17 nm. Recently, similar result were independently observed by Hann et al [30].…”

Section: Experimental Validation Using the Equivalent Monolayer Modelsupporting

confidence: 86%

Pixel-integrated thin-film filter simulation and scaling trade-offs

Goossens

2021

Preprint

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“…To make the images of the different wavelengths comparable to each other, the data set was finally normalized to the highest value of all channels. 9 5 Perpendicular Incidence of Light on the Sensor Figure 10(a) shows the corrected signal of channel 1 under perpendicular illumination using a wavelength of 914 nm. According to the manufacturer, the channel is most sensitive for this wavelength.…”

Section: Measurement Proceduresmentioning

confidence: 99%

“…[6][7][8] The investigated sensor addresses a wide range of applications such as agriculture, food inspection, or medical imaging. 9 With the presented characterization, a first impression can be gained as to whether or not these sensors are also suitable for quantitative spectral measurements, as they are necessary, for example, in the field of optical metrology.…”

Section: Introductionmentioning

confidence: 99%

Detailed characterization of a mosaic based hyperspectral snapshot imager

et al. 2020

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Some widely used optical measurement systems require a scan in wavelength or in one spatial dimension to measure the topography in all three dimensions. Novel hyperspectral sensors based on an extended Bayer pattern have a high potential to solve this issue as they can measure three dimensions in a single shot. This paper presents a detailed examination of a hyperspectral sensor including a description of the measurement setup. The evaluated sensor (Ximea MQ022HG-IM-SM5X5-NIR) offers 25 channels based on Fabry-Pérot filters. The setup illuminates the sensor with discrete wavelengths under a specified angle of incidence. This allows characterization of the spatial and angular response of every channel of each macropixel of the tested sensor on the illumination. The results of the characterization form the basis for a spectral reconstruction of the signal, which is essential to obtain an accurate spectral image. It turned out that irregularities of the signal response for the individual filters are present across the whole sensor.

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“…4,5 They are also particularly susceptible to fabrication tolerances. 6,7 Another approach, proposed by Bacon 8 and Courtes et al, 9 relies on spatial sampling using a microlens array in an intermediate image plane. This allows one to generate and capture a spectrum for each aperture on a conventional image sensor.…”

Section: Introductionmentioning

confidence: 99%

“…One of the main advantages of the proposed sensing principle is a quite large freedom of choice concerning spatial and spectral sampling in arbitrary image patches. Furthermore, compared with the IMEC SRFA sensor investigated by Hahn et al, 6,7 the method is superior in the detection of spectral shifts, is less sensitive to manufacturing tolerances, does not necessarily need a pixelwise calibration, is more robust to varying ray angles, and does not require any further spectral filters for proper operation. However, the proposed method leads to broader spectral channels at a given spatial resolution.…”

Section: Introductionmentioning

confidence: 99%

Diffraction-based hyperspectral snapshot imager

2022

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We present a method of hyperspectral snapshot imaging that is based on diffraction in an intermediate image plane. In this intermediate image, plane diffracting microstructures are used to deflect light toward an iris that performs spectral filtering. The method is related to imaging spectrometry with a reduced spectral resolution. However, the spectral shifts of the signal are detected very accurately at a potentially low cost. Our prototype system is capable of detecting a spectral shift of 0.5 nm, and the spectral operating range reaches from 510 to 700 nm. Application-specific arrays of microgratings are lithographically manufactured and lead to custom spatial and spectral sampling of an (intermediate) image. Compared with filter-based hyperspectral snapshot imaging, this approach avoids the difficult manufacturing of the mosaic filter array, but the spatial and spectral resolutions will become coupled. This leads to an uncertainty product for spatial and spectral resolutions. We explain the basic principle and show an experimental verification based on a first laboratory prototype.

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Detailed characterization of a hyperspectral snapshot imager for full-field chromatic confocal microscopy

Cited by 7 publications

References 0 publications

Pixel-integrated thin-film filter simulation and scaling trade-offs

Pixel-integrated thin-film filter simulation and scaling trade-offs

Detailed characterization of a mosaic based hyperspectral snapshot imager

Diffraction-based hyperspectral snapshot imager

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