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Spectrally tailored hyperpixel filter arrays for efficient imaging of chemical compositions

Taylor-Williams, Michaela; Cousins, Richard; Williams, Calum; Bohndiek, Sarah E.; Mellor, Christopher J.; Gordon, George S. D.

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Michaela Taylor-Williams

Richard Cousins

Calum Williams

Sarah E. Bohndiek

George S. D. Gordon


Richard Cousins


We present a method for designing and fabricating 'HyperPixels': pixel filter arrays with custom spectral transmission properties that enable efficient imaging of specific chromophores or fluorophores. Multispectral imaging typically targets particular spectral bands to uncover the spectral properties of tissue in combination with spatial resolution. Unmixing spectral properties can uncover the type and quantity of chromophores or fluorophores due to their unique spectral absorption or emission. Pixelated filter arrays atop imaging sensors are low-cost techniques used to achieve multispectral imaging. Typically, the filter pixels exhibit bandpass spectral behaviour, allowing only a fraction of the incident light to reach the sensor. As a result, narrowband filter pixels trade off high spectral resolution with optical power loss. A way to avoid this issue and improve the signal to noise ratio (SNR) for individual targets is to use a filter array where individual pixels are matched to a target chemical compound's reflectance or emission spectrum. Simulations show a > 5-fold improvement in SNR under realistic noise conditions. These matched optical filters can also reduce the complexity of software or hardware spectral unmixing algorithms, offering the potential for real-time imaging of target compounds. We present a method for tailoring spectral transmission of individual pixels by building HyperPixels comprising multiple Fabry-Perot resonator subpixels with varying bandpass properties (FWHM = approximately 50-60 nm, thicknesses 75-150 nm) that collectively have the desired transmission spectrum. We used a numerical optimization process to design filter arrays for simultaneous detection of methylene blue and indocyanine green, commonly used in cancer diagnostics by clinicians. We then fabricated filters for indocyanine green detection using grayscale lithography with pixel sizes down to 5 µm and individual subpixels down to 0.5 µm and characterized them for their spectral properties.


Taylor-Williams, M., Cousins, R., Williams, C., Bohndiek, S. E., Mellor, C. J., & Gordon, G. S. D. (2022). Spectrally tailored hyperpixel filter arrays for efficient imaging of chemical compositions. Proceedings of SPIE, 11954,

Journal Article Type Conference Paper
Conference Name SPIE Photonics West 2022
Conference Location San Francisco, United States
Acceptance Date Dec 31, 2021
Online Publication Date Mar 2, 2022
Publication Date Mar 2, 2022
Deposit Date Jan 4, 2022
Publicly Available Date Mar 2, 2022
Journal Proceedings of SPIE
Print ISSN 0277-786X
Publisher Society of Photo-optical Instrumentation Engineers
Peer Reviewed Peer Reviewed
Volume 11954
ISBN 9781510647794
Keywords Multispectral imaging; filter arrays; fluorescence imaging; biomarker imaging; greyscale lithography; atomic force microscopy; spectral characterization
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Additional Information Copyright 2022 Society of Photo?Optical Instrumentation Engineers (SPIE). One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this publication for a fee or for commercial purposes, and modification of the contents of the publication are prohibited.


Spectrally Tailored HyperPixel Filter Arrays For Efficient Imaging Of Chemical Compositions Final 27 Dec 21 (774 Kb)

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