Projection – Digital Cinema – 3D Omnia (Gwangmyeong, South Korea) has introduced an improved polarization modulator for 3D digital cinema that the company says will significantly increase the efficiency of polarized 3D systems, thereby increasing the screen brightness of the 3D image for an exhibitor who doesn’t have the option of buying a higher-output projector.
The 3D Omnia polarization modulator differs from other LC-based polarization modulators by using only a single Pi-cell in its construction. The company says all other polarization modulators on the market use two LC Pi-cells in series to modulate the polarization in a single-projector polarization based projection system. In these two-cell modulators, the light output of the projector is first converted to linear polarization by a static polarizer. This initial polarization can be done with either an absorptive polarizer, leading to a >50% light loss at the polarizer, or a polarization recovery system, leading to a much smaller loss. The two LC cells are used alternately to convert the linear polarized light to left and right circular polarized light. First one cell is activated and converts the linear polarization to right-circular polarized light. Then the first cell is deactivated and the second cell is activated to convert the linear polarized light to left-circularly polarized light.
- Specifications of the Prima Stella polarization modulator
Details of how the 3D Omnia system converts unpolarized light into left and right circular polarized light using only a single Pi-cell are not given. The company does say the system works with either absorptive polarizers or with polarization conversion systems such as the RealD XL system.
According to 3D Omnia, the use of a single cell has a number of advantages over the use of two cells:
- The single cell has a faster response time of 1ms vs 2ms for the two-cell design. This faster transition allows reduced dark time between images and therefore higher efficiency and reduced crosstalk.
- Since only one cell is used, there is no optical bonding between the two cells. This optical bond can yellow with age, affecting the total throughput and colorimetry of the projected image.
- The single cell has 25% higher throughput than the dual-cell design.
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- Prima Stella contrast vs angle compared to a dual-cell system.
The single cell has a wider acceptance angle than two cells, allowing the use of short-throw projection lenses with throw ratios as low as 0.5:1. This makes the unit usable in rear projection 3D applications as well front projection.
While 3D Omnia is a new company, (founded 2014), it has partnered with Spectro Screen (Pyeongtaek, South Korea). Spectro Screen was founded in 1995 and delivered its first products, extra-wide cinema projection screens, in 1998. Spectro Screen currently makes a variety of projection screens, including silver screens for polarized 3D applications. Another 3D Omnia partner was 3D Populi, although no information is available on that company.
According to 3D Omnia, the Prima Stella polarization modulator applies not only to the Cinema, but also to business projectors and home theater as well. The links to these applications are not yet working on the 3D Omnia page.–Matthew Brennesholtz
