# A Spatially Uniform Illumination Source for Widefield Multi-Spectral Optical Imaging

> **NIH NIH R43** · IRIS KINETICS INC · 2024 · $293,588

## Abstract

Project Summary
The main objective of this proposal is to develop a new multi-spectral light source with exceptional illumination
uniformity we call “Effective Uniform Color-Light Integration Device (EUCLID)” for biological imaging applications.
Our project's primary goal is to show how EUCLID impacts multispectral imaging applications and validate in
mesoscale brain imaging, a popular neurophotonics application. We anticipate that EUCLID can be integrated
into a wide range of biological microscopic and mesoscopic imaging applications, including super-resolution
microscopy and birefringence microscopy. In biological widefield imaging application, illumination homogeneity
is a crucial factor for excitation performance and resulting data quality. Yet, due to spatial and spectral non-
uniformity of conventional imaging systems caused by imperfect optical components, illumination corrections
require sophisticated solutions. Illumination design for multi-spectral imaging (MSI) is particularly challenging as
field uniformity across a wide range of wavelength is essential. Recent advancements in light emitting and laser
diode technology enables creation of multi-spectral light sources with previously unattainable compactness,
power, and controllability. Traditionally, achieving homogenous illumination at several wavelengths requires
combining collimated beams using dichroic mirrors or beam-splitters and precise alignment. Cost, complexity,
and absolute size of the illumination solution require careful consideration when developing a MSI application.
The significant novelty of EUCLID is the introduction of a conical geometry allowing for light integration, design
optimization and uniformity adjustments. The diffuse-reflective adjustable hollow cavity used in EUCLID alters
the source field distribution to compensate spatial non-uniformity caused by the imaging system's optical
components while allowing for uniform mixing of light from discrete sources with great efficiency. With a maximum
spatial deviation of 1% over a large field of view, preliminary experiments show significantly improved illumination
for multispectral imaging in both Nelsonian (critical) and Koehler configuration (FOV). EUCLID is also shown to
provide speckle-free laser illumination over a wide field-of-view with a plateau uniformity around 2% for a broad
spectrum. This uniformity introduced by the EUCLID is 3 times better than current state-of-the art flat-top
illumination technique. In this proposal, we propose to show EUCLIDs performance in multispectral mesoscale
brain imaging where neuronal activity (calcium signals), hemodynamic activity (hemoglobin oxygenation), and
neuromodulation (acetylcholine levels) are simultaneously monitored across the dorsal cortex of mice with
implanted ‘crystal skull’ windows. For that, we will develop two different EUCLID designs. The first one will accept
two different commercial LED bulb to provide oblique excitation light to monitor neuronal activ...

## Key facts

- **NIH application ID:** 10824047
- **Project number:** 1R43NS135877-01
- **Recipient organization:** IRIS KINETICS INC
- **Principal Investigator:** Elif Seymour
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $293,588
- **Award type:** 1
- **Project period:** 2024-09-19 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10824047

## Citation

> US National Institutes of Health, RePORTER application 10824047, A Spatially Uniform Illumination Source for Widefield Multi-Spectral Optical Imaging (1R43NS135877-01). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10824047. Licensed CC0.

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