| 摘要 |
<p>When the in-air length of an internal resonator of a laser source (401), which is obtained as the product of the length of the internal resonator of the laser source (401) and the refractive index of the internal resonator of the laser source (401), is denoted as Lld, the optical path length of a laser beam from the exit plane of the laser source (401) to a PBS (404) as calculated in terms of an in-air length is denoted as LBS, the optical path length of a signal beam from the PBS (404) to a reflective part of an optical disk (407) as calculated in terms of an in-air length is denoted as Lsig, the optical path length of a reference beam from the PBS (404) to a reference beam mirror (410) as calculated in terms of an in-air length is denoted as Lref, and an allowable interference optical path length of the laser beam is denoted as ∆L, the laser source (401), PBS (404), and reference beam mirror (410) are positioned so as to simultaneously satisfy Lsig + LBS <> s (Lld/m) (s: positive integer; m: positive integer), Lref + LBS <> t (Lld/m) (t: positive integer), and u (Lld/m) - (∆L/2) <= Lsig - Lref <= u (Lld/m) + (∆L/2) (u: integer).</p> |
