Optical Heterogeneity of Transparent Medium

KarpovichMaryia, Matsviayuk Anton

Supervisors: Mashutina Tatyana

State Institution of Education “Gymnasium №1 the town of Brest”,

Brest/Belarus,

1. Introduction

In the presented research we have explored the processes, which are accompanying the passage of light in an optically inhomogeneous substance. So, we are talking about graded-index optical waveguide. In an optically inhomogeneous medium optical properties are different, this leads to refraction of the light.Let’s have a look at the process of passing of optical emission through such a medium. Assume that the graded-index is changing in the direction of the ordinate axis continuously. Spreading in this medium, the rayis bent into the area with a higher refractive index.Thus, by creating a certain optical heterogeneity of the medium, we can control the trajectory of the light beam in this medium. Thepurposeofourresearchisto study methods of controlling the trajectory of the light wave in transparent medium. This scientific problem is actual nowadays, as it is connected with the development of fiber-optic communication means, the creation of effective optical devices, which can work with minimal aberrations. The optical fibers, in which it is possible to control the direction of the light wave (so-called “smart skin”) can, contribute to the development of robotics and micro-measuring equipment.

2. Methods of research

Liquid and solid optically inhomogeneous substances with a linear change of the refractive index were experimentally obtained.The propagation of a light beam in a diffuse layer (a concentrated solution of NaCl and water) and in a temperature-inhomogeneous layer was investigated. In such medium the light beam propagates along the trajectory, described by the equation of the "chain" line [1]:

(1).

It was especially interesting to create diffuse optical inhomogeneity in solids.So, we have created flat lenses. They can be used in devices, where a large number of lenses is needed. To this we have made thin round plates from the gelatin andglycerin solution. After 20 minutes of soaking in water the refractive index of the substance of such a lens radially decreases from the center in accordance with the formula:

(1)

here: y – the distance from the center of the plate to a point, F – the focal length of the lens, h – the thickness of the plate [1]. Similarly, selphocks (thin rods with a radially decreasing refractive index) were made.In the research it is theoretically and practically shown that in selphocks the light ray propagates along a spiral line with small aberrations. Ambiguous results were obtained by studying the trajectory of a light beam in an optically inhomogeneous sphere.

3. Results

A comparison of the trajectory of the light ray and the chain line is given in Pictures 1 and 2.

Picture 1. The propagation of a light beam in a diffuse layer / Picture 2. The chart of the chain line, built in the program Mathcad 15

Studying the optical properties of a flat lens, we have obtained thatthe refractive index of the lens material linearly decreases from its center indeed.

Thechart 1. Dependence of the refractive index on the distance from the center of the flat lens.

Picture 3.The trajectory of the light beam in the rod

4. Conclusion

Thus, in the presented research it is shown, that the passage of light in a substance can be controlled. A deeper study of these issues is likely to lead to the emergence of new technologies and materials.

5. Literature

Mayer, Varaksina“Light in an inhomogeneous medium”. Moscow: Fizmatlit, p. 232, (2007).