Automated method for wavelength estimation in a two-beam interferometer based on the on–off switching of two laser-diode sources

Abstract

In this manuscript a method is proposed to estimate the wavelength of a laser diode source, under the scheme of a two-source Twyman–Green interferometric setup. This proposal is based on the count and ratio of the interfering fringes generated by two laser diode sources with a standard and unknown wavelength when they are independently switched on–off. The viability of the proposed experimental setup allows it to be easily replicated and used for research or teaching purposes, where special topics in optics for undergraduate or graduate students are required.

An optically-driven macroscopic cantilever

“…For resonance detection in the context of dynamic force microscopy (to be discussed in next section), one could either use a fibre optic interferometer [10][11][12] or a MI. We chose the latter, because we had previously exploited its usefulness for another undergraduate experiment [13] and its integration into the undergraduate laboratory is commonplace nowadays with a number of reports describing the MI technique in details [14][15][16][17].…”

A double beam Fabry–Perot interferometer for measuring laser wavelength

“…In a simple experiment the wavelength of a red HeNe laser was measured using two parallel slits [1]. The more advanced measurements use standard instruments, such as a spectrometer and interferometer [2][3][4][5][6][7]. For pedagogic purposes the Michelson interferometer and Fabry-Perot interferometer are employed in the physics laboratory.…”

“…To avoid a separate calibration, two lasers are used. In this method the laser from the measured source and the standard reference source are passed into the same interferometer system [4,5]. The system which is based on the Michelson interferometer provides an accurate result that is important in the research laboratory.…”

“…The second setup uses the Twyman-Green interferometer and includes filters before counting the interference fringes. In addition, the lasers have to be independently switched on-off [5].…”

Simple setup for wavelength estimation by using the Airy disk with didactical purposes

“…There are some suggested methods that use optical setups to measure the wavelength of a laser source, which in the visible spectrum goes from 400 to 700 nanometers (nm) corresponding to a color range from violet through red [1][2][3][4]. Some of them are based on interferometers which count the number of fringes or the spacing between them [5][6][7], while some others use the distance between the diffraction orders generated by a diffractive element such as a diffraction grating [8] or a ruler [9]. In this manuscript, common electronics and low-cost optical elements such as a circular aperture and a generic laser diode source will be used to provide an easy implementation with the aim of estimating the wavelength of the source, with didactical purposes.…”