| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical element unit and lens which can suppress the coupling efficiency degradation even if decentering errors are still remaining. SOLUTION: When representing the optical axis height difference h<SB>sag</SB>between the aspherical optical surface S2 and the spherical surface byΔ<SB>sag</SB>, the coupling efficiency degradation can be suppressed even if decentring errors are still remaining by making the differenceΔ<SB>sag</SB>larger than the lower limit in expression (1): (1) 6.5(μm)<Δ<SB>sag</SB><30(μm); (2) h<SB>sag</SB>=fb×NA<SB>SHG</SB>×1.3+0.10(mm); and (3) NA<SB>SHG</SB>=α/f (3), provided that fb represents the back focus of the lens,αthe optical axis height of the 1/e<SP>2</SP>intensity of the input light flux, and f the focal length of the lens. COPYRIGHT: (C)2008,JPO&INPIT
|
