Design of a Simple and Robust Asymmetric Ellipsometer for Terahertz

G. Rana [1], S. P. Duttagupta [1], P. Deshmukh [2], S. S. Prabhu [2],
[1] Indian Institute of Technology Bombay, Mumbai, Maharashtra, India
[2] Tata Institute of Fundamental Research, Mumbai, Maharashtra, India
Publié en 2015

Ellipsometry has been the most efficient and accurate method for determining optical constants of a given material. In this article, we present a novel concept for designing an ellipsometer for Terahertz frequencies based on reflection geometry THz Time Domain Spectroscopy. The present ellipsometers for THz are either based on parabolic mirrors cavities or lens based cavities. The former one has a problem of critical alignment of the optics to achieve variable angular incidence and the later one, though free of aforementioned issue, is having inherent issue of aberration. To solve the aforesaid shortcomings of the two existing type set ups we propose a set of two asymmetric ellipsoids with a common focus. We have achieved maximum angular variation of incident wave up to ~65º.

A comparative study is done using optimized single axis accelerometer and dual axis and double gimbal accelerometers are designed with different cantilever beam types i.e. perforated, non perforated, spring type and cross spring type. The models are simulated to find the most sensitive model.

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