Ex vivo recreation of Haidinger’s brush

Although the human eye is generally insensitive to polarization, Haidinger’s brush represents a rare instance in which polarization sensitivity becomes perceptible. This entoptic phenomenon is thought to arise from the dichroic xanthophyll pigments in the macula and the birefringence of Henle fibers. In this study, we recreate Haidinger’s brush using a polariscope, demonstrating that multiple combinations of retardance and diattenuation can reproduce a comparable visual effect in an <i>ex vivo</i> setting. A simulation using CIE 1931 color matching functions and D65 illumination was developed to model wavelength-dependent polarization effects. The characteristic yellow–blue appearance of Haidinger’s brush is shown to be evident even with spatially-varying rotations of the fast-axis retardance orientation.