| 摘要 |
A laser absorption apparatus comprises a resonant optical cavity having highly reflective mirrors. Laser light undergoes multiple reflections while the spacing of the mirrors is varied as a function of time. The intensity of light transmitted across one of the mirrors is measured as a function of time and the measured intensity is transformed from the time domain to the frequency domain. The absorption coefficient of sample contained within the cavity, or reflectively of the mirrors, or change in polarisation state of the light, or coherence length of the light beam can be determined from the transform or from the intensity itself.
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