Reflecting prism for bringing plane of polarization in rotation

FIELD: optics.

SUBSTANCE: reflecting prism can be used in projection displays and other optical devices. Reflecting prism for bringing plane of polarization in rotation is made of optically transparent material and it has shape of rectangular parallelepiped with three truncated angles in form of prisms. Isosceles triangular bases of those prisms belong to mutual perpendicular sides of parallelepiped. One side face of any prism has to be cutting plane which forms one of three working surfaces of reflecting prisms. Working surfaces of prism are disposed at angle of total internal reflection and they are made for series reflection of incident light beam which cones to reflecting prism at angle of 90 degrees to its side to form exit light beam being co-linear to incident beam. Working surfaces at reflection of beam provide turn of plane of polarization.

EFFECT: improved reliability of operation.

6 cl, 3 dwg

 

The invention relates to optical elements, and more particularly to reflective prisms to rotate the plane of polarization, and can be used in projection displays and other optical devices.

Declared prism rotates the polarization vector of the electromagnetic wave at a certain angle, which is often required in many optical applications.

As a rule, as a rotator of the plane of polarization is applied to a half-wave plate. An example of a polarization Converter with a half-wave plate is described in Japan patent No. SHO 63-168622 [1], in which the polarization luciasgueglia plate located immediately behind the light source, for dividing the non-polarized light emitted by the light source, two beams of linearly polarized light, the polarization plane which is spatially shifted by 90°. Then the plane of polarization of one of the data of polarized light is rotated 90° when passing through the TN liquid crystal display (LCD) panel, which functions as a rotator of the plane of polarization, and propagation direction of light is the same as that of the other beam with an unrotated plane of polarization. So get combined linearly-polarized light which is then projected on the LCD panel, which forms the image./p>

To rotate the plane of polarization in many applications also use the effect of double refraction of the crystal. Optical elements based on this effect, called birefringent wave plates or slow-wave plates (or briefly just wave plates and moderators). The velocity of propagation of the ordinary and extraordinary beam through a birefringent materials strongly depend on their refractive indices. The difference in the velocities of propagation leads to the difference of phases when combined rays. In the case of a linearly polarized beam ϕ=2πd(ne-nabout)/λ (where ϕ phase difference; d is the thickness of the wave plate; nenaboutthe refractive indices of ordinary and extraordinary ray, respectively; λ - wavelength). At any particular wavelength phase difference is controlled by the thickness of the wave plate. In applications using plates of several kinds: one-eighth wavelength, quarter-wave, half-wave and wave plates.

The above lucanespecialities and birefringent plate made of optical crystal. The lack of optical crystals is their high cost. In addition, the phase difference between the P and S polarized components of light that passes through half-wave plate is, varies significantly depending on the wavelength of light, resulting in the data of the half-wave plate in the polarization converters in projection systems display in the projected image can be color violations.

Closest to the claimed invention is an optical device, described in U.S. patent No. 4822150 [2], which consists of a set of prismatic surfaces made with the possibility of transmission of linearly polarized incoming beam of light and the formation of a linearly polarized output beam that is collinear to the incoming beam and polarized orthogonal to the polarization direction of the incoming beam. The disadvantages of this device include an extremely large dimensions of the device, limiting its use in many applications, as well as its low optical efficiency due to losses that occur when a large number (seven) of the reflection beam to be performed to get the result.

The task of the claimed invention is to provide a reflective prism to rotate the plane of polarization, which has a low production cost, small size, high optical efficiency at the output does not make the color distortion in the reflected light.

The task resinatum create a reflective prism to rotate the plane of polarization, which is made of optically transparent material and has the shape of a rectangular parallelepiped with three truncated corners in the form of prisms, equilateral triangular base are belong to mutually perpendicular sides of the parallelepiped, and one of the side faces of each prism is a plane, which forms one of the three working surfaces of the reflective prism, and work surfaces are at an angle of total internal reflection and is made with possibility of consistent reflection of the incoming beam of light to a reflective prism normal to the side, and forming the output beam of light, collinear to the incoming beam, and the work surface when the reflection light beam provide rotation the plane of polarization.

For the functioning of the prism, it is important that the first working surface was formed plane that intersects both bases, large side and the edge of the box, along which abut the major and minor sides of the parallelepiped, the second working surface was formed plane that intersects the upper base, a lower side and two large lateral faces of the parallelepiped, and a third working surface was formed secus the second plane, which crosses both smaller sides, the greater the side, not truncated first working surface, and the edge of the box, along which abut the bottom base and a large side plate, and the first work surface is configured to reflect the second working surface of the incoming beam of light to a reflective prism normal to its greater side, a truncated third working surface, the second working surface is configured to reflect the light beam to the third working surface, and a third working surface configured to reflect the light beam on the large side, a truncated first working surface, and facing the light beam is directed in the same direction as the incoming beam.

For the functioning of the prism, it is important that the first working surface was formed plane that intersects both bases, large side and the edge of the box, along which abut the major and minor sides of the parallelepiped, the second working surface was formed plane that intersects the upper base, a lower side and two large lateral faces of the parallelepiped, and a third working surface was formed plane that intersects the baie smaller side, large side, a truncated first working surface, and the edge of the box, along which abut the bottom base and a large side plate, and the first work surface is configured to reflect the second working surface of the incoming beam of light to a reflective prism normal to its greater side, not the truncated third working surface, the second working surface is configured to reflect the light beam to the third working surface, and a third working surface configured to reflect the light beam on the big side, not truncated third working surface and the exiting light beam is directed in the opposite direction relative to the incoming beam.

For the functioning of the prism, it is important that the refractive index of the optically transparent material of the prism was greater than the refractive index of the surrounding medium, and the reflected light beam from the working surfaces was due to the effect of total internal reflection.

For the functioning of the prism, it is important that the work surface had a coating of reflective material.

For the functioning of the prism it is important that the reflection light beam from the working surfaces were rotating the plane of polarization of h is 90° .

The technical result of the claimed invention is the reduction of production cost, reducing the size, increasing the optical efficiency output and eliminate color distortion by creating a prism of transparent optical material with three reflecting surfaces arranged in a certain way.

For a better understanding of the present invention further provides a detailed description involving graphic materials.

Figure 1. Diagram of the reflective prism to rotate the plane of polarization: 1.1 - with equally directed incoming/outgoing rays and 1.2 diagram of light passing through the prism, made according to the invention.

Figure 2. Diagram of the reflective prism to rotate the plane of polarization: 2.1 - with multidirectional incoming/outgoing rays and 2.2 - scheme of light passing through the prism, made according to the invention.

Figure 3. Scheme of polarization of the light guide, which is made on the basis of the reflective prism to rotate the plane of polarization of differently incoming/outgoing rays, made according to the invention.

Consider the principle of operation of the claimed invention. In both cases (figures 1 and 2) reflective prism 1 to rotate the plane of polarization is made of optically transparent material and has the shape of Pramogu inogo parallelepiped with three truncated corners 2, 3, 4 in the form of prisms, equilateral triangular base are belong to mutually perpendicular sides of the parallelepiped, and one of the side faces of each prism is a plane, which forms one of the three working surfaces 5, 6, 7 reflective prism. And working surfaces are at an angle of total internal reflection and is made with possibility of consistent reflection of the incoming light beam 8, which enters the reflective prism 1 is normal to the side, and with the possibility of the formation of the escaping light beam that is collinear to the incoming beam, and the reflected light beam from the working surfaces 5, 6, 7 is the rotation of the polarization plane.

Reflections from the working surfaces 5, 6, 7 occur according to the rule of total internal reflection, bearing in mind that the prism should be surrounded by the external environment, the refractive index of which is less than the refractive index of material of prism, or due to the presence of the reflecting layer on the working surfaces.

In the first embodiment, the reflective prism with the same directional incoming/outgoing rays (Figure 1), the light beam 8 enters the reflective prism 1 through the big party 9 normal to its surface and falls on the first working surface 5, is reflected from the first working item is surface 5, then falls on the second working surface 6 and is reflected from the second working surface 6, and then falls on the third working surface 7, is reflected from the third working surface 7 and out through the large side face 10 prism 1 as the output beam 11, which extends in the same direction as the incoming beam 8. Plane H polarization of the output beam 11 is rotated by 90° relative to the direction of the plane of the V polarization of the incoming beam 8 (shown by arrows). The rotation of the polarization plane depends only on the spatial transmission angle of the beam inside the prism.

The second embodiment of the reflective prism in accordance with the claimed invention shown in figure 2. As can be seen, in this embodiment of the claimed invention, the third working surface 7 formed by cutting off from the corner of the lower base of the parallelepiped prism, while the working surface 7 crosses the bigger side 10 of the box. This suggests that the resulting output beam of light 11 will be distributed collinear, but in the opposite direction compared to the direction of propagation of the incoming beam 8.

Figure 3 shows an example of the application of the claimed invention in the polarization of the light guide, which includes a light guide 12, the inclined surface 13, a reflector 14 and otrajat the optimum prism 15 to rotate the plane of polarization of differently incoming/outgoing rays, made according to the invention. Incoming non-polarized light is separated into two polarized components S and P polarization of the inclined surfaces 13, after which one of the component transform reflective prism 15 to rotate the plane of polarization of the light with S-polarization is reflected from the inclined surfaces and exits through the side of the light guide and the light with P-polarization passes through the light guide 12, emerges from its opposite end and is incident on the reflective prism 15. In the reflective prism component 15 with a P-polarization component is converted into S-polarization by rotation of the polarization plane and sent back to the light guide 12, in which the first light is reflected from the inclined surfaces 13, and then from the reflector 14, and then exits through the side of the light guide. Moreover, the incoming non-polarized light is separated into two polarized components of the inclined surfaces 13 due to the reflection at the Brewster angle. Given that when the light is incident at the Brewster angle component with P-polarization is not reflected inside the light guide 12 has a set of inclined surfaces 13, which is inclined at the Brewster angle to the propagation direction included in the light guide of the light and act as polarizers. Thus, only the component of light with S-polarization of whom shall be expressed and exits through the side of the light guide 12, as component with the P-polarization passes through the light guide and exits the opposite end. The inclined surface inside the light guide can be performed in different ways. One way consists in bonding a transparent adhesive sets of inclined plates with the formation of unit plates inclined at an angle of 45°. Another method involves bonding the transparent glue two prismatic surfaces, with the inner surface will be tilted towards the input end of the fiber, and from him. Plane polarization components of the light with P-polarization is rotated 90° declared reflective prism, made in the variant shown in figure 2, when this is converted to a component with S-polarization.

For the manufacture of the claimed prism of solid sheets of transparent material or polymer can be used various technologies: cutting corners and polished edges of a cube or a rectangular parallelepiped, alloy wheels.

The claimed invention can be used in projection displays, optical modulators, isolators, and other optical devices.

Although the above embodiment of the invention has been set forth to illustrate the present invention, the experts it is clear that various modifications, additions and substitutions, without departing from the volumes of the a and the sense of the present invention, disclosed in the accompanying claims.

1. The reflective prism to rotate the plane of polarization, is made of optically transparent material and having the shape of a rectangular parallelepiped with three truncated corners in the form of prisms, equilateral triangular base are belong to mutually perpendicular sides of the parallelepiped, and one of the side faces of each prism is a plane, which forms one of the three working surfaces of the reflective prism, and work surfaces are at an angle of total internal reflection and is made with possibility of consistent reflection of the incoming beam of light to a reflective prism normal to the side, and forming the output beam of light, collinear to the incoming beam, and work surfaces when the reflected light beam provide rotation of the polarization plane.

2. Reflective prism according to claim 1, characterized in that the first working surface formed plane that intersects both bases, large side and the edge of the box, along which abut the major and minor sides of the parallelepiped, the second working surface formed plane that intersects the upper base, the lower side is the thoron and two large lateral faces of the parallelepiped, and the third working surface formed plane that intersects both smaller sides, the greater the side, not truncated first working surface, and the edge of the box, along which abut the bottom base and a large side plate, and the first work surface is configured to reflect the second working surface of the incoming beam of light to a reflective prism normal to its greater side, a truncated third working surface, the second working surface is configured to reflect the light beam to the third working surface, and a third working surface configured to reflect the light beam on the big side not truncated first working surface and the exiting light beam is directed in the same direction as the incoming beam.

3. Reflective prism according to claim 1, characterized in that the first working surface formed plane that intersects both bases, large side and the edge of the box, along which abut the major and minor sides of the parallelepiped, the second working surface formed plane that intersects the upper base, a lower side and two large lateral faces of the parallelepiped, and a third working surface shall knosti formed plane, which crosses both smaller sides, large lateral direction, which intersects the first working surface, and the edge of the box, along which abut the bottom base and a large side plate, and the first work surface is configured to reflect the second working surface of the incoming beam of light to a reflective prism normal to its greater side, not the truncated third working surface, the second working surface is configured to reflect the light beam to the third working surface, and a third working surface configured to reflect the light beam on the big side, not truncated third working surface, moreover, the exiting light beam is directed in the opposite direction relative to the incoming beam.

4. Reflective prism according to any one of claims 1 to 3, characterized in that the refractive index of the optically transparent material of the prism, the more the refractive index of the surrounding medium, and the reflected light beam from the working surfaces is due to the effect of total internal reflection.

5. Reflective prism according to any one of claims 1 to 3, characterized in that the surfaces have a coating of reflective material.

6. Reflective prism according to any one of claims 1 to 3, from ecaudata fact, when the reflected light beam from the working surfaces is provided by the rotation of the polarization plane by 90°.



 

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