A Multispectral Projector for Advanced Vision Science

Saturday, May 18, 2024, 12:45 – 2:15 pm, Banyan/Citrus

Organizers: Dr. Jonathan Tong, Staff Scientist at VPixx Technologies; Dr. Lindsey Fraser, Staff Scientist at VPixx Technologies

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The human eye contains five distinct classes of photoreceptors: the short, medium, and long-wavelength cones, the rods, and the intrinsically Photosensitive Retinal Ganglion Cells (iPRGCs). Although each type is maximally activated by a unique wavelength of light, their spectral sensitivity bandwidths overlap, so that most light sources will activate multiple photoreceptor types. Therefore, researchers who wish to functionally isolate a given receptor type will use the “silent substitution” technique, in which pairs of light are used to selectively modulate the activity of a target photoreceptor type while maintaining a static level of activity in the other photoreceptor types.

However, conventional displays, with RGB primaries alone, are often insufficient for producing the spectral outputs, or light pairs, required for most “silent substitution” applications. In principle, it is necessary to have as many primaries as receptor types that you wish to target or “silence,” with carefully selected spectral profiles.

In this presentation, we will discuss how we designed a 4-primary “multispectral” projector (PROPixx) that can modulate activity (spatially and temporally) in one class of receptors while “silencing” three other receptor types, such as targeting rods while silencing the three cone types. We will review the technical challenges involved in building projectors with 4+ primaries, and the computational modeling approaches we took in selecting primaries for different silent substitution applications. We will also expand on other vision science applications that can be achieved with multispectral displays.

Finally, our guest speaker, Dr. Pablo Barrionuevo (Justus-Liebig Universität Giessen, CONICET-UNT), will highlight how he and his collaborators have used the multispectral PROPixx in their research.

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VPixx is a privately held company serving the vision research community by developing innovative hardware and software tools for vision scientists (http://www.vpixx.com).  For more general educational content, visit the VPixx Online Classroom and Library (VOCAL): www.vpixx.com/vocal