Abstract
We describe a technique that allows control of visual stimuli quality through the use of a setup with a polymer dispersed liquid crystal (PDLC) film positioned in the optical pathway of one or both human eyes. Nowadays, PDLC films allow alteration of the resolution and contrast limits of the transmitted light due to continuous change in the light scattering that is obtained by the application of an AC electrical field. In our experimental setup, the use of a wide-aperture up to area of 20 x 15 cm 2 PDLC sheet is combined with a flat-screen PC display or with a modified display emission block without its interference filter unit and with an installed individually controllable colored light-emitting diode (LED) backlight. In the latter case, the spatial structure of visual stimulus remains constant, but the PDLC switching-on timing for intensity, color, and contrast of visual stimuli control is done by a PC via an Arduino USB interface. Arduino applies a voltage to the backlight colored LEDs and the low voltage up to 30 – 80 V to light-scattering PDLC sheet. Modifications to this setup can improve the resolution of the timing and screen stimulus intensity and color purity, and increase the flexibility of its application in visual research tasks. A particular use of PDLC scattering sheets involves the altering of the stimuli input strength of the eye in different binocular viewing schemes. In such applications, a restricted-optical-aperture PDLC element is mounted in a goggle frame, and the element is controlled by the application of low-voltage AC field. The efficacy of the setup is demonstrated in experiments of human vision contrast sensitivity adaptation studies. Studies allow to determine the characteristic time of the contrast sensitivity altering of 4 s during adaptation phase and the same order of the characteristic time during recovery. DOI: http://dx.doi.org/10.5755/j01.ms.22.4.12907
Highlights
Advances in materials science promote studies in many fields of optics including vision research
Previous studies [5] have reported on the development of a model eye with an element filled with lipid solution that affords good scattering control
As the first example of the use of electrically controllable light scattering for eye cataract modeling, a study has reported on the use of lanthanum-modified lead zirconate titanate (PLZT) electro-optic ceramics [10]
Summary
Advances in materials science promote studies in many fields of optics including vision research. As the first example of the use of electrically controllable light scattering for eye cataract modeling, a study has reported on the use of lanthanum-modified lead zirconate titanate (PLZT) electro-optic ceramics [10]. This material allows “smart” variation in the device optical properties via external control in several ways, for example, by the application of an electrical field or based on the intensity of incident light [12, 13]. The primary advantage of the PDLC over related materials is that it requires low control voltages (30 – 80 V), thereby allowing the implementation of easy-to-use devices in experiments on human vision perception. The main aim of the present work is the development of a modified experimental technique that allows inducing of fast and controllable light scattering of visual stimuli and its application in visual perception studies on contrast sensitivity adaptation
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