SU1576902A1 - Demonstration device on physics - Google Patents

Abstract

The invention relates to educational demonstration devices in physics. The aim of the invention is to expand the demonstration capabilities and increase the consistency of the instrument. To achieve this goal, a physics demonstration device containing a light source, a condenser, a light filter, a polarizer, an optical object, an analyzer, an objective lens and a screen mounted sequentially on an optical bench has an optical compensator located between the optical object and the analyzer, and the optical compensator is made in the form of a package of flat transparent plates placed in a metal frame with screws that create a bending or torsional stress, and interference is used as a light filter One-way light filter mounted on a swivel base. 2 hp f-ly, 2 ill.

Description

The invention relates to educational demonstration devices in physics.

The purpose of the invention is to expand the demonstration capabilities and increase the consistency of the instrument.

. Figure 1 shows the scheme of the proposed device with plates, deformed by bending; figure 2 - the same, with plates, deformable torsion.

The device contains a light source 1, a condenser 2, an interference light filter 3, a rotary support 4, a polarizer 5, an optical object 6, an optical compensator 7, an analyzer 8, a lens 9 and a screen 10.

The compensator is placed in a cassette having means for the task of bending or twisting the component of the compensator to a package of plates arranged perpendicular to the optical base.

B as a compensator, a package of flat transparent plates is used, in which the creation of flexural or torsional deformations allows one to transform an elliptical double refraction or rotation of the polarization plane into an offset of neutral lines. Moreover, the magnitude of the displacement is proportional to the elliptical birefringence, if a bend deformation is created in the plates, or the angle of rotation of the polarization plane, if the torsion deformation is created in the plates. The neutral line is a dark band,

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which is clearly visible1 in a large audience on the screen.

The use of such a compensator makes it possible not only to increase the consistency of the demonstration (by visualizing the distribution of the birefringence value in the object or by simultaneously observing several objects), but also provides a demonstration of a number of new patterns (for example, dispersion in optically active materials, secondary electro-optical effect, etc. ).

The light flux from the light source 1, passing the condenser 2, the light filter 3, the polarizer 5, becomes linearly polarized and passes through the optical object 6 and the optical compensator 7, then, after passing through the analyzer 8 and the lens 9, it hits the screen 10 where the image is projected optical object.

When the transparent plates are bent in the form of an arc, the lines along the center of each plate remain non-deformable, i.e. are neutral areas. A part of the plates above the neutral line is under tension, and a part below this line is compressive. As a result, the upper part of the plates behaves as a positive crystal and the bottom one as a negative uniaxial crystal. If such a packet of plates is viewed in parallel polarized light with crossed poloid, then the light will be completely extinguished only along neutral lines. Therefore, when bending a pack of transparent plates in polarized light, a system of parallel dark lines is observed against a bright floor. The device allows to demonstrate artificial optical anisotropy. photoelasticity phenomenon. For this, the plates of the optical element are first demonstrated without compression, and then, gradually increasing the compression value, the appearance of bands of higher order is shown. Again, only dark neutral lines are established and an object model is introduced into the field of view; made of plexiglass and subjected to external influence. Distorted neutral lines are clearly visible on the screen, which show where the model has compressive stresses and where there is tension and tension.

the displacement of the neutral line proportional to the magnitude of the voltage at one or another point of the object.

Thus, the screen shows not only the voltage distribution in the optical object, but also the voltage that is not visible visually without the optical compensator 7. When demonstrating the principle of action

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Ronal lines are shifted up and down relative to the initial position.

In addition, the device allows you to demonstrate the principle of the plate in wavelength. As the object 6 set the plate in the wavelength / 575 nm (the so-called sensitive plate). On the screen, the upper part of the plates of the optical element takes on an indigo blue color, and the lower part takes on a purple-red one.

When demonstrating an electro-optical effect in crystals, an electro-optical crystal is used as an optical object (for example, DKDR ZnSe). When a constant electric field is applied to it, the screen shows a displacement of the neutral line, the magnitude of which is proportional to the electric field. When the direction changes to the opposite neutral line, it shifts to the other side. This is a demonstration of the electro-optical effect under a constant mechanical stress, i.e. when the crystal is mechanically free. When demonstrating the dispersion of linear birefringence, a crystal with a significant dispersion of birefringence in the visible spectrum is used as an optical object, for example, a single crystal of zinc selenide, doping of which with magnesium leads to birefringence. The magnitude of the displacement of the neutral line, visible on the screen, decreases as the wavelength from 0.64 to 0, 5 µm decreases to zero.

When torsional stresses are created in the transparent plate, the lines in the center of the plate remain undeformable, i.e. represents

neutral area. As a result, the upper part of the plate behaves as a right-handed crystal, and the bottom - as a left-handed crystal (or vice versa). Therefore, when the package of transparent plates is twisted in polarized light, a system of parallel dark lines is observed against a light floor.

The device allows to demonstrate the following regularities: rotation of the plane of polarization with aa-, hara solution. To do this, take 6 tubes with windows as an optical object, fill them with a sugar solution from 10% to saturated. Then these. tubes (3-4 pieces) are installed in the path of the rays between the polarizer and the optical compensator 7. After focusing on the screen 10, lines are visible, the amount of displacement of which is proportional to the sugar concentration in the tube, therefore the amount of displacement for each tube is different;

rotation of the polarization plane by quartz. For this purpose, several plane-parallel plates of different thickness, on the order of 3-10 mm, cut perpendicular to the optical axis, are used as the optical object 6. It is necessary to have right- and left-handed quartz plates. Plates are installed between the polarizer 5 and the optical compensator 7 and demonstrate the following phenomena: the displacement of the neutral line up or down when changing the levorotatory to the right rotational plate; show an increase in the angle of rotation with a large plate thickness, for which the sequence is folded; few thin plates, while the offset of the neutral lines of the compensator will increase;. an interference filter of 0.64 µm is used and, rotating it around the vertical axis (the wavelength of the light changes), the dispersion of bireflection is shown. The amount of displacement of the neutral line will depend on the wavelength.

The device can be used to demonstrate the effects of: Farad electrography, piezo-optic activity. For this purpose, a specially oriented crystal is placed between the polarizer and the optical compensator 7. When externally applied (magnetic or electric field, mechanical stress),

5 offset of the neutral line, indicating the rotation of the polarization plane.

Claims (3)

Invention Formula 0 1. A demonstration device in physics containing a light source, a condenser, a light filter, a polarizer, an optical object, an analyzer, an objective lens and a screen, successively installed on an optical bench, in order to enhance the demonstration capabilities and increase the consistency has an optical compensator located between the polarizer and the object, made in the form of a pack of plates installed perpendicular to the optical axis in a cassette having means for deforming the plates, and the light filter is made nterferentsionnym and set to rotary mediated re. 2. Apparatus pop-1, characterized in that the means for deformation is installed in the cassette with the possibility of the task of bending deformation plates. 3. Apparatus pop-1, characterized in that the means for deformation is installed in the cartridge with the possibility of the task of torsion deformation plates. five 0 five T you / H rm 3/5 6 7 Figure 2 YU