| 摘要 |
Aligning a stable ring resonator by the use of an inversion mechanism inside the resonator and a pair of anti-symmetric masks. Each mask has opaque and clear parts and the masks are anti-symmetric in that, in use, one mask is positioned so that its opaque and clear parts are anti-symmetric to the opaque and clear parts of the other mask when it is in position. One mask is placed between the radiation source and the beam splitter while the other mask is placed between the beam splitter and the focal plane on which the two beam portions created by the beam splitter focus. One beam portion is directly reflected from the beam splitter and the other portion is transmitted into the resonator and is inverted while following a beam path within the resonator before being outcoupled through the beam splitter in a much weakened state. Thusly positioned, the anti-symmetric masks have the effect to attenuating the intensity of the reflected beam portion, so that the relative intensities of the transmitted and the reflected beam portions are more equal when they arrive at the focal plane. This, in turn, makes the alignment of the two focal spots easy. When the two spots merge completely the ring resonator is aligned.
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