Psychophysical discrimination of radially varying polarization entoptic phenomena

The incorporation of structured light techniques into vision science has enabled more selective probes of polarization related entoptic phenomena. Diverse sets of stimuli have become accessible in which the spatially dependant optical properties can be rapidly controlled and manipulated. For example, past studies with human perception of polarization have dealt with stimuli that appear to vary azimuthally. This is mainly due to the constraint that the typically available degree of freedom to manipulate the phase shift of light rotates the perceived pattern around a person's point of fixation. Here we create a structured light stimulus that is perceived to vary purely along the radial direction and test discrimination sensitivity to inwards and outwards radial motion. This is accomplished by preparing a radial state coupled to an orbital angular momentum state that matches the orientation of the dichroic elements in the macula. The presented methods offering a new dimension of exploration serve as a direct compliment to previous studies and may provide new insights into characterizing macular pigment density profiles and assessing the health of the macula.