Appeal No. 2004-1069 Page 6
Application No. 09/569,616
beam collector 28 directs the divergent light from the light source 2 through an entry
surface 16 of the beam expanding light pipe 14. A plurality of microprisms 44 are
positioned adjacent to a reflecting surface 20 of the beam expanding light pipe 14. The
reflecting surface 20 is, in this embodiment, substantially perpendicular to the entry
surface 16 of the beam expanding light pipe 14. Light that enters the beam expanding
light pipe 14 is directed by the microprisms 44 so that the light exits the beam
expanding light pipe 14 at an emission surface 22 that is opposite the reflecting surface
20. Additionally, for certain applications, it is also desirable to have output light
propagate from the emission surface 22 of the beam expanding light pipe 14 in a
direction that is not normal to the emission surface 22. A prismatic diffuser can be used
with the light expanding system 10 to direct the output beam to propagate in a desired
direction and/or increase the divergence angle to a desired value.
The light expanding system 10' shown in Figure 4 includes a beam collector 28'
and a beam expanding light pipe 14' that each have a generally circular cross-section.
The circular cross-sectional sectional shape of the beam expanding light pipe
14' is truncated at two locations to form opposing flat surfaces 20 (reflecting surface)
and 22 (emission surface) that extend along the entire length of the beam expanding
light pipe 14'. The beam expanding light pipe 14' also has an entry surface 16' and an
end surface 18' that each have a truncated circular cross-sectional shape. In this
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Last modified: November 3, 2007