| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light guide plate capable of simply attaining a surface light source which has few light loss caused by stray light and is excellent on use efficiency of light, and an optical system having the light guide plate. <P>SOLUTION: The light guide plate 1 having a reflective sub-wavelength diffraction grating 3 generates zero-order light and minus first-order light only in the reflective sub-wavelength diffraction grating 3, and extracts the minus first-order light as emitting light, and transmits the zero-order light to generate new minus first-order light by satisfying the conditional expressions: sin<SP POS="POST">-1</SP>(1/n)<θ<SB POS="POST">1...</SB>(1), λ/än(sinθ<SB POS="POST">1</SB>+1)}≤Λ<min[2λ/än(sinθ<SB POS="POST">1</SB>+1)}, λ/än(-sinθ<SB POS="POST">1</SB>+1)}]... (2), and sin<SP POS="POST">-1</SP>äsinθ<SB POS="POST">1</SB>-λ/(n×Λ)}<sin<SP POS="POST">-1</SP>(1/n)... (3), where, λ: wavelength of light, n: refractive index of a light guide plate body, Λ: period of reflective sub-wavelength diffraction grating, θ<SB POS="POST">1</SB>: an incident angle of light against the reflective sub-wavelength diffraction grating. <P>COPYRIGHT: (C)2013,JPO&INPIT |
