CS247730B1 - Monochrome Light Polarizer - Google Patents

Abstract

A monochromatic light polarizer with high resistance to high intensity light fluxes and the ability to perfectly polarize monochromatic light, especially for use in lasers, made of an optically uniaxial crystal on which two surfaces are formed, at least one of which forms an angle φ with the plane ρ determined by the optical axis (1) and the intersection (2) of both surfaces corresponding to 0.3 to 0.9 times arcsin ηλ_1, where ηλ is the refractive index of an ordinary or extraordinary ray with a wavelength λ, and is provided with an anti-reflection layer (3) for light with a wavelength λ incident on this surface at an angle corresponding to 0.9 to 1.1 times arcsin (n^inj, or the second surface lies in the plane p of the optical axis (1) and is provided with a reflective layer (3) for light with a wavelength λ

Description

The present invention relates to a monochromatic light polarizer with high resistance to luminous fluxes of high intensity and the ability to perfectly polarize monochromatic light.

Light polarizers find a wide range of applications in optical measuring instruments, in which the ability to polarize white light is usually required without requiring the polarizer to withstand high light intensity luminous fluxes. In lasers, polarizers are a component of shutters and are therefore exposed to extremely high luminous fluxes. However, the polarizer function is generally required in these cases only for monochromatic light, which allows the construction of a polarizer with dielectric layers made on substrates of optically isotropic materials whose surface is inclined relative to the direction of incident light. These are either plates or prisms on which the said layers are formed. In practice, however, perfectly polarizing layers are difficult to form, and therefore several substrates are chosen, which, however, especially in the case of lower layer quality, results in loss of light by reflection.

However, these disadvantages are completely eliminated by the monochromatic light polarizer according to the invention, which consists of an optically uniaxial crystal on which two surfaces are formed, at least one of which forms an angle with the plane defined by the optical axis of the crystal and the intersection of the two prism surfaces φ of a magnitude corresponding to 0,3 to 0,9 times the arcsin η _λ ^_1 , where η _λ is the refractive index of the ordinary or · extraordinary beam of wavelength λ and is provided with an aintireflective layer for light of wavelength Λ corresponding to 0.9 to 1.1 times the arcsin (n _x sin ,, J. When using monochromatic light is incident obliquely on the surface provided with an antireflection coating and is refracted so that the light passed through the polarizer on a selected kmitosměru perpendicular to the optical axis of the crystal. If, the second surface forms an angle of 0.3 to 0.9 times the arcsin tor ¹ with the optical axis plane The light beam of the desired frequency passes in full intensity, while ^one beam of the opposite frequency is attenuated according to the quality of the antireflection layer and the magnitude of the angle φ, but always angularly different from the beam of the desired frequency direction, for example in laser resonators sufficient. If the second surface lies in the plane of the optical axis of the crystal and is provided with a reflective layer for light of wavelength λ, the polarizer reflects the light, wherein in the reflected light the beams of opposite polarization are again angularly differentiated.

The monochromatic light polarizers according to the invention thus fully obviate the disadvantages of light refracting polarizers on surfaces oriented obliquely to the incident beam and at the same time can be made of low birefringence crystals when used in lasers.

In the following, the invention is described in more detail with reference to the accompanying drawing.

Figures 1 and 2 show an arrangement with two faces, at least one of which forms an angle φ with the plane p. Fig. 1 is an oblique view, Fig. 2 is a top view. The drawings show the optical axis 1 of the crystal, the intersection 2 of the two surfaces and the plane p defined by them. Furthermore, the angle φ between the surfaces and the plane p is shown. In FIG. 3 is oblique and FIG. The optical axis 1 of the crystal, the intersection 2 of the two surfaces and the plane p defined by them, as well as the angle φ that the plane p is from the surfaces, are again shown.

Example 1

A calcite monocrystal (n ₀ = 1.652; n _e = 1.483 at λ = 632.8 nm) was made with a cross section perpendicular to the height of the isosceles triangle with apex angles of 70 °, 70 ° a. The optical axis 1 bisected a 40 ° angle of the prism cross-section. The 40 ° angle surfaces were provided with an antireflective layer 3 by alternating silica and titanium dioxide vapor for monochromatic light at a wavelength of 632.8 nm at an incidence angle of 34.4 ° with polarization in the plane of incidence. The antireflective layer 3 allows light with said polarization to pass from air to prism and on the second surface provided with the antireflective layer 3 back to the air with minimal losses. In the prism, the light beam travels perpendicular to the optical axis 1 and its polarization corresponds to the proper frequency. When it enters the air, it is diverted by 28.8 ° from the exiting beam; the extraordinary beams are deflected from the regular beams by passing through a calcite prism so that the angle between them is 7.11 °. The prism was used as a He-Ne laser light polarizer.

Example 1 a d 2

From corundum single crystal (n ₀ =

1,763; n _e = 1,755 at λ = 694,3 nm) a prism with cross-section perpendicular to the height of the right-angled triangle was made. The optical axis 1 of the single crystal lay in a single off-surface area at an angle of 22 ° to the prepoin surface. This reflective surface was provided with a reflective layer 3 for light having a wavelength of 694.3 nm, while the transition surface was provided with an antireflective layer 3 for light of the same wavelength, coming at an incidence angle of 41.1 ° so that the refracted beam polarized perpendicular to the plane of impact,

247, ie extraordinary, was perpendicular to the above-mentioned off-surface. The polarized beam is again reflected in the axis of light incident on the prism, while the beam polarized perpendicular to this beam, ie the orderly one, is substantially attenuated and reflected in the axis bordering the axis

3a of the incident beam at an angle of 0.7 °. The prism was used as a back mirror ruby laser having a laser rod, in which the crystallographic c-axis is parallel to the geometrical axis, for the purpose of ^one polarization of the laser radiation.

Claims (1)

SUBJECT A monochromatic light polarizer, characterized in that it consists of an optically uniaxial crystal on which two surfaces are formed, at least one of which forms an angle ψ of 0 corresponding to the plane p, determined by the optical axis (1j of the crystal and the intersection (2) of both surfaces). 3 to 0.9 times the arcsin η _λ ^_1 , where η _λ is the refractive index of the order OF THE INVENTION or of an extraordinary beam of wavelength λ and is provided with an antireflective layer (3) for light of · wavelength, impinging on this surface at an angle corresponding to 0.9 to 1.1 times the arcsin (n., Siin, _tl ) or the second surface lies in the plane p of the optical axis (1) and is provided with a reflective layer (3) for light of wavelength Λ.