SU1339469A1 - Interference-polarized filter - Google Patents

Abstract

The invention relates to optical instrument making and allows improving the filter selectivity by increasing the spectral distance between adjacent transmission maxima. At the foot of the foot, of N identical birefringent crystal plates 2,3 ... are made in the form of a uniaxial ferroelectric single crystal 4 with a regular lamellar domain structure. The spontaneous polarization vectors in the adjacent domain plates 2, 3 are turned in opposite directions and parallel to the domain domain. the border. Under the influence of an electric field, the optical axes C of each domain are rotated about the Z axis, parallel to the main axis of the polarizer 1, at the azimuthal angles c /. 2 Il. (L oo oo with NU O5 CO .1

Description

The invention relates to optical instrumentation and can be used for the selection of light of a given length in length in astronomy, optics, and various types of spectral analysis.

The purpose of the invention is to improve the filter selectivity by increasing the spectral distance between adjacent transmission maxima.

FIG. 1 shows a device based on a ferroelectric crystal with an anti-parallel domain structure; in fig. -2 - filter transmission spectrum.

The Scholz-type interference-polarization filter contains successively located along the axis polarizer 1, a stack of N identical birefringent crystal plates 2, 3, etc., made in the form of a uniaxial ferroelectric single crystal 4 with a regular lamellar domain structure, and an orthogonal field The analyzer element 5 is located on the rizator. On two opposite lateral surfaces of the single crystal 4 (Fig. 1, the surfaces perpendicular to the X axis) parallel to its polar axis are electrodes (not shown), Inonii to a power source. The spontaneous polarization P and -P vectors in neighboring domains, for example, 2 and 3, are turned in opposite directions (antiparallel) and parallel to the domain wall. When applied to the electrodes of the electric field

The optical axes from each axis parallel to the XZ plane are turned around on an axis, Z, parallel to the main plane of polarizer 1, at azimuthal angles, defined by

o (- (-) -V, where d 45 / N;

i 1,2,3, ..., n.

The filter works as follows

In a ferroelectric crystal with a lamellar antiparallel domain structure, under the action of an electric field applied to the crystal (E.,), due to the rotation of the optical indicatrix (and therefore optical axes) in antiparallel domains at angles of different signs to /, there is a Scholz-type periodic structure. At transmission wavelengths L

The filter plate domains are half wave. Therefore, the first phase plate-domain rotates the polarization vector of the light OA specified by polarizer 1 by an angle c / symmetrically relative to the optical axis of the plate. With respect to itself, the polarization vector of the light OA, after passing through the first plate, will turn through an angle of 2 °. A similar effect on the vector of polarization of light will produce the second plate, etc. Consequently, N plate domains rotate the OA vector by an angle

2No /. If the angle 2Nc / is 90, i.e. 0/45 ° / N, the light with wavelengths / freely passes through the analyzer.

The domain layer structure should be formed in many oxygen-octahedral ferroelectrics grown by the Czochralski method and having a high temperature value.

Curie. For example, a layered domain structure is observed in niobataly (Nbt ,, TC 1200 ° C) in barium-sodium niobate (BaNa, Nb jO, TC). Regular (periodic) layer

The domain structure is formed in these crystals, for example, due to the rotation of the growing crystal in an asymmetric thermal field, which leads to the formation of regular growth layers and domains associated with them. Periodic domains (layers of the required thickness and orientation) can also be obtained by electrostatic post-growth treatment. The visualization of the domain structure can be performed by etching or by an electro-optical method. The thickness of the plate domains in the crystals of sodium barium niobate and lithium niobate can lie in the range of 3–50 µm or more.

0

five

Example. The use of a ferroelectric crystal barinatp.

ribon niobate (lp pz - n 0.1) - with a domain thickness of d 3 microns with a total number of domains N-10, it is possible to manufacture a Scholz-type filter with a bandwidth at half-height of L. 4 A, the opacity area (U / 4-10 A (Fig. 2). The magnitude of the electric field required for the desired reversal of the index of the refractive indices in the domains, 1.7 kV / mm.

Claims (1)

Formula invented and An interference polarization filter containing a polarizer sequentially arranged along the axis of the filter is a stack of N identical bi-refractory crystal plates with azimuth angles o /, between the main planes of the plates and the main plane of the polarizer, (-I) V, where d 45 ° / N; i 1,2,3, .., N, a is also an orthogonal polarizer and analyzing distance between adjacent transmission maxima, a stack of N identical birefringent crystal plates made in the form of a uniaxial ferroelectric single crystal with a regular lamellar domain structure, on two opposite the side surfaces of which are 10, parallel to the polar axis of the monocrystal, are electrodes connected to a power source, and the vectors of spontaneous polarization in adjacent domains are turned into a counter element, tlichayuschiys By the fact that, in order to improve the selectivity, 15 hollow sides and parallel to the domain of the filter by increasing the spectral limit. The distance between adjacent transmission maxima, the foot of N identical birefringent crystal plates are made as a uniaxial ferroelectric single crystal with a regular lamellar domain structure, on two opposite side surfaces of which are parallel to the polar axis of the single crystal, electrodes are located connected to the power source, and the vectors of spontaneous polarization in the neighboring domains are deployed in counter , all W about 21I // 2 "/ 1 fi-fO ZIX (STR 5000 Compiled by V. Kravchenko. Editor N. Rogulich Tekhred L. Oliynyk Order 4214/34 Circulation 521 Subscription VNIIPI USSR State Committee for inventions and discoveries I13035, Moscow, Zh-35, Raushsk nab., d. 4/5 Production and printing company, Uzhgorod, st. Project, 4 .2 9000 Proofreader A. Zimokosov