  Illumination uniformity is a critical parameter for excitation and data
extraction quality in widefield biological imaging applications. However,
typical imaging systems suffer from spatial and spectral non-uniformity due to
non-ideal optical elements, thus require complex solutions for illumination
corrections. We present Effective Uniform Color-Light Integration Device
(EUCLID), a simple and cost-effective illumination source for uniformity
corrections. EUCLID employs a diffuse-reflective, adjustable hollow cavity that
allows for uniform mixing of light from discrete light sources and modifies the
source field distribution to compensate for spatial non-uniformity introduced
by optical components in the imaging system. In this study, we characterize the
light coupling efficiency of the proposed design and compare the uniformity
performance with the conventional method. EUCLID demonstrates a remarkable
illumination improvement for multi-spectral imaging in both Nelsonian and
Koehler alignment with a maximum spatial deviation of ~1% across a wide
field-of-view.
