This paper presents an improved method of high precision tilt measurement using a phase shifting cyclic interferometer. Tilt measurement with a cyclic interferometer is a highly stable and reliable experimental technique and tilts as low as 5 μrad has been reported using the same. Here we employ Polarizing Phase Shifting Interferometry (PPSI) as well as multiple reflections for improving the sensitivity. Using a combination of these two techniques tilts as low as 500 nrad has been measured. © 2019 Elsevier Ltd

Angarai Ramanathan Ganesan

Department Of Physics

Valiyaparambil Chacko Pretheesh Kumar

Interferometers

Nanotechnology

Experimental techniques

High-precision

Highly stables

MULTIPLE REFLECTIONS

PHASE SHIFTING INTERFEROMETRY

PHASE-SHIFTING

POLARIZATION PHASE

TILT MEASUREMENT

Interferometry

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Optics and Laser Technology

Measurement of tilt plays an important role in metrological applications and consequently, several methods have been proposed in the recent past. Classical interferometric methods can measure angles with high accuracy but are easily susceptible to external turbulences. We propose to use a cyclic interferometer to measure tilt in which the sensitivity to tilt measurement is double when compared with that of the classical Michelson interferometer. Since the counter propagating beams travel identical paths, the interferometer is insensitive to external vibrations and turbulence and thus can be used under harsh environmental conditions. The novelty in the technique lies in creating multiple reflections in the tilt mirror to enhance the measurement accuracy by the way of increasing the sensitivity. This paper presents the basics of the interferometer and experimental results to quantify the increase in sensitivity. By increasing the number of reflections, it is shown that sensitivity can be further improved to measure tilt angles below 5 μrad. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Journal	Data powered by TypesetOptics and Laser Technology
Publisher	Data powered by TypesetElsevier Ltd
ISSN	00303992
Open Access	No