Please note! This essay has been submitted by a student.
A 3D projection system was set up( left and right eye) in order to study the principles behind 3D viewing as done in a theatre. At a time, there are two images present, however, each eye can see only one image. This is due to the light being circularly polarized which differs in the direction of rotation. Circularly polarized light is composed of two plane waves out of phase by π/2 with equal amplitude. Circularly polarized light is created by passing randomly polarized light first through a linear polarizer which linearly polarizes the light and then passing it through a quarter wavelength retarder plate which is used to convert the linearly polarized light to circularly polarized and by keeping it at 450 with respect to the linear polarizer, half of the light becomes perpendicular to the other half. The thickness of the quarter wavelength is chosen such that there is a 900 phase shift between the two waves. The quarter wavelength retarder plate is so named as it has two refractive indices and the light through the larger refractive index is slowed down which causes the phase shift. Each side of the 3D glasses is also made up of a linear polarizer (closer to the eye) and a quarter wavelength plate(closer to the screen). Only one type of rotation direction is allowed to pass through and the other one is blocked such that each eye can see one image.
First, two images named ’LEFT’ and ‘RIGHT’ were projected on the screen whose projections were aligned on top of each other. The images were observed through a linear polarizer which showed transmission of light when the angle between incident linear polarization and the polarization axis was 00 and no transmission when observed at 900. The images were then looked at together with a linear polarizer and a quarter wavelength plate. Next, 2 photos from different angles were projected on the screen on top of which 3D glasses were kept. These were then observed through a linear polarizer and quarter wavelength plate and the images seemed to form one 3D image when viewed from both the eyes at the same time.
In the first part, either the left or right images were seen depending upon the angle (00 or 900). In the second part, each eye could see one image as the 3D glass in front of each eye blocked the other type of polarization hence blocking out the second image present which caused a 3D effect when seen with both the eyes.