We present a low-cost resource that aims to facilitate the teaching process of subjects related to optical fibers, given that it presents a practical application of this technology. The main purpose of this resource is to send a color image through optical fibers with a laser diode from one computer and receive it with a photoresistor on another computer, with a total estimated setup-cost of twenty dollars. The setup includes a visual user-interface, for both computers, programmed with the software LabVIEW, which lets to select and prepare an image for a proper sending and receiving. In this proposal we have used arduino boards and low-cost plastic optical fibers used in ornaments.
In this manuscript, a simple and low-cost method for phase-shifting interferometry by the rotation of a polarizer is presented. The principle of the proposal relies on the polarization aberration introduced by a cube beam-splitter due to its geometry, to the angular dependence with the coating and to the polarization angle of the input beam. The interferometric setup performs as a two-window common-path interferometer in which the added phase-shifting is achieved by simply rotating a polarizer at the interferometer output. The viability of the proposal is sustained with experimental results in which the phase-shift value and the resulting wavefront are calculated with Farrel’s technique and the Three-step PSI algorithm respectively.
This work presents a simple, low-cost opto-mechatronic educational device that determines the refractive index for liquids, which is performed automatically on the computer with an Arduino UNO card through a LabVIEW graphical interface. The operation of the apparatus is based on passing a laser beam through a container with the given substance; then, the refracted beam will be detected with a photoresistor which is moved along the axis by a stepper motor. The distance traveled by the motor until the beam of light impinges on the photoresistor together with known constants (distances between the fixed elements, thickness of the container and refractive index of this material) will be used to calculate the refracted angle through the unknown medium, as well as its refractive index, by linking all the variables in a formula derived from Snell's Law.
In this manuscript a simple and easy to implement method that uses the Airy disk generated from a Fraunhofer diffraction pattern due to a circular aperture will be used to estimate the wavelength of the illuminating laser source. This estimation is based on the measurement of the Airy disk diameter, whose approximation is directly proportional to the wavelength of the light source and to the distance between the aperture and the image plane; and inversely proportional to the diameter of the aperture. Due to the characteristics and versatility of the present proposal, this is perfectly suitable to be applied in graduate or undergraduate physics laboratories or even in classrooms for educational and/or demonstrative purposes.
A low-cost and fully automated process for phase-shifting interferometry by continuously changing and turning on-off the input voltage of a laser diode under the scheme of an unbalanced Twyman-Green interferometer setup is presented. The input signal of a laser diode is controlled by a Data Acquisition (NI-DAQ) device which permits to change its wavelength according to its tunability features. The automation and data analysis will be done using LabVIEW in combination with MATLAB. By using Carré algorithm the phase map is obtained. Measurements of visibility and phase-shift to verify the PSI requirements are also shown.
A method to create homogenous polarized light based on non-quadrature amplitude modulation is proposed. This method consists in the addition of two fields out of phase different from mπ and in the variation of their amplitudes only for obtaining a resulting field modulated in both phase and amplitude. This principle is used to modulate the vertical component in both phase and amplitude, while the horizontal component is varied in amplitude only keeping constant its phase, thus any amplitude relation and phase difference between components can be created and therefore any polarization state could be obtained. A theoretical model will be shown, and it will be sustained with numerical simulations of several polarization examples.
A new method to generate inhomogeneous spatial phase variation and phase retrieval is proposed. This method is based under the scheme of three beams forming two Mach-Zehnder interferometers in series, where one arm is considered as the probe beam, while the other two will compose the reference beam where a phase difference within the range of (0,π ) is kept and this remains spatially variable in opposition to the classical PSI method. The generation of phase-shifts is done by on-off nonquadrature amplitude modulation. Although the phase difference between the reference beams are spatially variable having as a consequence that the visibility and phase variations are inhomogeneous, it will be demonstrated that it is still possible to retrieve the phase of the object and also to measure the phase variation. An analytic discussion and experimental results will be shown to sustain the proposed method.
A new method to create elliptically polarized light based on the quadrature amplitude modulation is proposed. This method begins from an unpolarized light and does not use any classical methods, as for instance those using polarizers and retarders or also by refraction, scattering, dichroism or birefringence effects. This method is based on the amplitude modulation of two optical waves in quadrature in order to modulate the field in amplitude and phase. With this idea, we show that any amplitude relation and relative phase difference between components can be created and therefore any polarization state can be carried out. A theoretical model will be shown, and it will be sustained with numerical simulations of several polarization examples
A new method for phase-shifting interferometry based on the wave amplitude modulation is proposed and discussed. This proposal is based on the interference of three waves, where two waves attend as two reference waves and the other wave attends as a probe wave. Whereby, three interference terms are obtained, but because of a phase difference of π/2 between the two references is kept constant, one of the three terms will be dropped while the two remaining will be put in quadrature. Under these conditions the resulting pattern is mathematically modeled by an interferogram of two waves, where an additional phase is given by the amplitude variations of the reference waves. In this paper, both a theoretical model and some numerical simulations are presented
A novel phase shifting interferometry method based on the variation of the electric field under the scheme of a
three beams interferometer is proposed. One beam contains the object under study, that makes this beam the
probe beam; the other two will be consider as the reference beams with a phase difference of π 2 . Due to
this, one of the three resulting interference terms will be cancelled and the two remaining will be in
quadrature. Applying some trigonometric identities, we show that the resulting interference pattern could
become modeled by the interfering of two beams with an additional phase term; we obtain that the tangent
function of the additional phase depends on the division of the amplitude of the third field divided by the
amplitude of the first, and it is possible to group the sum of the squares of these fields in a square amplitude.
To recover the phase by using the phase shifting interferometry techniques it is necessary to keep constant
the visibility of the interference pattern, at first sight we can think that this is not possible because the
variations of the field amplitude affect the visibility of the patterns. However this problem is solved if the values
of the amplitude corresponding to the fields one and three are seen as an ordered pair contained over an arc
segment at the first quadrant. We justify the viability of this method by a theoretical analysis and a numerical
simulation of the interference of three beams under the conditions mentioned above.