4. DLP System General Description
4. DLP SYSTEM GENERAL DESCRIPTION
4.1 F90 optical principle
Optical Principle
The F90 illumination cons ists o f two identical light p aths combined using a dual rod system. E ach pa
th includes the following:
48 blue 455 nm Laser Diodes (LD) grouped into 3 banks c onsisting of 8 (2x4 array) LDs. The individual las er bea ms are combined
using mirrors and a focusing lens.
The light is focuse d on a static d iffuser placed just before the entrance of a glass integrating rod.
The scattered light is then reflected multiple times in the integrating ro d, c reating uniform luminance at the rod exit.
The rod exit surface is then imaged onto the rotating P hosphor W heel (PW) by the u se of collimating len
ses and a dichroic mirror
which only reflects blue and IR light.
Image 4-1
The phos phor absorbs the blue laser light, and emits a broad b and yellow light which is reflected back towards the dichroic m irror,
where it is transmitted, and focused onto the dual rod system.
A small portion of the blue light is transmitted through a clear segment of the PW, and is relayed around to the back of t he dichroic
mirror. T here it is reflected a second time and combined with the yellow light from the PW before it is focused on the dual rod sy stem.
The dual rod system consists of two solid integrating rods (one for eac h illumination path) and a hollow integrating rod combining
the two seamlessly. This exit surface is imaged onto the DMD using traditional relay optics and TIR prism.
To create Red and G reen color
, a co lor whee l is placed after the hollow rod exit surface, which is syn chronized w ith the PW s in
each illumination path. This is again s ynchronized with the DMD producing time sequential Red, G reen and B lue colors on the w all
perceived by the human eye as white light.
By using the internal illumination iris the contrast ratio can be increased, and by sliding in the motorized color filter (located next to
the iris) a broader color gam ut can be achieved.
723–0016 F90 01/12/2017
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