Zhejiang Sci-Tech University

Qiuhong Tian

Liping Yan

Benyong Chen

Zhengrong Sun

Measuring refractive index of air based on laser synthetic wavelength interferometry. The Apparatus includes a dual-frequency laser that emits orthogonal linear polarized light of wavelengths &#x3bb;and &#x3bb;, a beamsplitter, two polarizing beamsplitters, two corner-cube retroreflectors, a quartz vacuum cavity of length L disposed in the measuring optical path in parallel to the light propagation direction, and two detectors. The apparatus is used to measure the refractive index of air using the dual-frequency laser to emit orthogonal linear polarized light with wavelengths &#x3bb;and &#x3bb;, using the beamsplitters, corner-cube retroreflectors, quartz vacuum cavity, and detectors. The integer N and fraction &#x3b5; of interference fringes of wavelength &#x3bb;are determined. The refractive index of air n is obtained by using the length L of the vacuum cavity, integer N and fraction &#x3b5; of the interference fringes of wavelength &#x3bb;. The measurement is accurate up to 10or higher, and has strong anti-disturbance ability to the environment.

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Zhejiang, China

Qiuhong Tian