DLP7000UV Datasheet, PDF (31/51 Pages) Texas Instruments – LVDS Type A DMD

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8.5 Window Characteristics and Optics
DLP7000UV
DLPS061C – MAY 2015 – REVISED SEPTEMBER 2015
NOTE
TI assumes no responsibility for image quality artifacts or DMD failures caused by optical
system operating conditions exceeding limits described previously.
8.5.1 Optical Interface and System Image Quality
TI assumes no responsibility for end-equipment optical performance. Achieving the desired end-equipment
optical performance involves making trade-offs between numerous component and system design parameters.
Optimizing system optical performance and image quality strongly relate to optical system design parameter
trades. Although it is not possible to anticipate every conceivable application, projector image quality and optical
performance is contingent on compliance to the optical system operating conditions described in the following
sections.
8.5.2 Numerical Aperture and Stray Light Control
The angle defined by the numerical aperture of the illumination and projection optics at the DMD optical area
should be the same. This angle should not exceed the nominal device mirror tilt angle unless appropriate
apertures are added in the illumination and/or projection pupils to block out flat-state and stray light from the
projection lens. The mirror tilt angle defines DMD capability to separate the ON optical path from any other light
path, including undesirable flat-state specular reflections from the DMD window, DMD border structures, or other
system surfaces near the DMD such as prism or lens surfaces. If the numerical aperture exceeds the mirror tilt
angle, or if the projection numerical aperture angle is more than two degrees larger than the illumination
numerical aperture angle, objectionable artifacts in the display’s border and/or active area could occur.
8.5.3 Pupil Match
TI recommends the exit pupil of the illumination is nominally centered within 2° (two degrees) of the entrance
pupil of the projection optics. Misalignment of pupils can create objectionable artifacts in the display’s border
and/or active area, which may require additional system apertures to control, especially if the numerical aperture
of the system exceeds the pixel tilt angle.
8.5.4 Illumination Overfill
The active area of the device is surrounded by an aperture on the inside DMD window surface that masks
structures of the DMD device assembly from normal view. The aperture is sized to anticipate several optical
operating conditions. Overfill light illuminating the window aperture can create artifacts from the edge of the
window aperture opening and other surface anomalies that may be visible on the screen. The illumination optical
system should be designed to limit light flux incident anywhere on the window aperture from exceeding
approximately 10% of the average flux level in the active area. Depending on the particular system’s optical
architecture, overfill light may have to be further reduced below the suggested 10% level in order to be
acceptable.
Copyright © 2015, Texas Instruments Incorporated
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