ABSOLUTE DISTANCE MEASUREMENT USING FREQUENCY SCANNING INTERFEROMETRY | ||
| Journal of Scientific Research in Science | ||
| Article 7, Volume 32, part 2, November 2015, Pages 76-88 PDF (1.06 M) | ||
| Document Type: Original Article | ||
| DOI: 10.21608/jsrs.2015.19947 | ||
| Authors | ||
| M. Medhat1; M. Sobee2; H. M. Hussein* 2; O. Terra2 | ||
| 1Physics Department. Faculty of Science. Ain-Shams University, Cairo, Egypt | ||
| 2National Institute for Standard (NIS), Tersa St. Haram, code:12211, P.O.Box: 136 Giza, Egypt | ||
| Abstract | ||
| Absolute distance measurement is necessary for many applications where the distance to a fixed-target is required. In this paper, frequency scanning interferometry is implemented with an external cavity tunable diode laser, which has a wavelength scanning range of (665-675 nm), to measure distances up to 5 m absolutely (achieved by multi-reflection system). An ultra-low expansion (ULE) Fabry-Pérot (FP) cavity has been used as a reference to measure the tunable-laser scanning range. Absolute distance is determined by counting the synthetic fringes and FP peaks simultaneously while scanning the laser frequency. A fringe processing technique is developed to perform online distance measurement even though the tunable laser is not mode-hop free. This fringe processing method enables simple, fast and accurate distance measurements with repeatability ±3.9×10-6 L and combined uncertainty ±38.9×10-6 L which is limited by the calibration system used. | ||
| Keywords | ||
| Absolute distance; optical interferometers; mode hop; frequency scanning interferometry; Fabry-Pérot cavity | ||
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