Construction of an inexpensive molecular iodine spectrometer using a self-developed Pohl wavemeter around 670 nm wavelength

Abstract

We describe construction of an inexpensive Iodine Spectrometer with a home made Iodine vapour cell and a self developed wavemeter based on Pohl Interferometer, around 670 nm wavelength.This can be easily realised in an undergraduate teaching laboratory to demonstrate use of a diode laser interferometry using a Pohl interferometer and measurement of wavelength using image processing techniques.Visible alternative to the IR diode lasers, 670 nm diode laser used here give chance to undergraduate students to perform comprehensive though illustrative atomic physics experiments including the Zeeman effect, the Hanle effect, Magneto Optic Rotation (MOR) effect with a little tweaking in the present spectrometer. The advantage of the spectrometer is its ease of construction with readily available optics, electronics, evacuation and glass blowing facilities and easy analysis algorithm to evaluate the wavelength. The self developed algorithm of raster scanning and circular averaging gives the researcher insight into the basics of image processing techniques. Resolution approaching 0.5 nm can be easily achieved using such simple setup.

A review of optical interferometry techniques for VOC detection

“…The Pohl interferometer is an amplitude splitting interferometer in which light beam from a point source is reflected from the surfaces with different optical properties (refractive index, reflectivity) forming an interference pattern [79]. The Pohl configuration offers a simple, quick and efficient approach for measuring the wavelength [38].…”