CPC G02B 27/0081 (2013.01) [G02B 5/28 (2013.01); G02B 27/0172 (2013.01); G02B 2027/0112 (2013.01)] | 19 Claims |
1. An optical expander device for displaying wide color images, comprising a waveguide plate (SUB1), wherein, the waveguide plate (SUB1) in turn comprises:
an in-coupling element (DOE1), comprising a first grating and a second grating with a first grating period (d1a) and a second different grating with a second grating period (d1b), the first grating period (d1a) is different from the second grating period (d1b), the first grating diffracts the input light (IN1) to form a first guided light (B1a) propagating in a first direction, and the second grating diffracts the input light (IN1) to form a second guided light (B1b),
a first expander element (DOE2a) to form third guided light (B2a) by diffracting the first guided light (B1a),
a second expander element (DOE2b) to form fourth guided light (B2b) by diffracting the second guided light (B1b),
an out-coupling element (DOE3) to form first output light (OB3a) by diffracting the third guided light (B2a), and to form second output light (OB3b) by diffracting the fourth guided light (B2b), the out-coupling element (DOE3) is arranged to form combined output light (OUT1) by combining the first output light (OB3a) with the second output light (OB3b),
a first spectral filter region (C2a), providing between the first expander element (DOE2a) and out-coupling element (DOE3) to prevent coupling of red light from the second guided light (B1b) to the out-coupling element (DOE3) via the first expander element (DOE2a), and
a second spectral filter region (C2b), providing between the second expander element (DOE2b) and out-coupling element (DOE3) to prevent coupling of blue light from the a first guided light (B1a) to the out-coupling element (DOE3) via the second expander element (DOE2b).
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