2510332 - February 2009
Inherent keystone correction of the image by placing the DMD device below the optical axis of the projection lens. This generally is required to achieve enough angular separation of the illumination and projection optics for packaging.
Smaller optical elements in the rear of the projection lens (before stop) due to finite pupil location. However, these designs typically have more elements in front of the stop due to limited space behind the stop, so front elements can grow quite large for fast throw ratios and may negate overall savings.
Figure 5. Effect of Projection Offset on Illumination Angle, Nontelecentric Design, Side View
Figure 6. Nontelecentric Optical Layout for Flat Projector Using Reflective and Refractive Illumination Elements (Isometric View)
Disadvantages of Nontelecentric Architecture Nontelecentric architectures have some disadvantages/challenges relative to others:
Nonuniform angles of incidence of the illumination at the device produce variation in the
absolute black level, even though the absolute level generally is much lower overall than other architectures.
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