SU1734064A1 - Unit to focus the microwave radiation into rectangular - Google Patents

Abstract

The invention relates to quasi-optical systems and can be used in plants for processing materials with focused radiation. The purpose of the invention is to ensure uniform distribution of the intensity in a rectangular beam section in the focal plane is achieved by focusing the Gaussian beam from the radiation source using a mirror, the shape of which is determined from a system of equations. 3 il.

Description

The invention relates to the creation of elements of quasi-optical systems that serve to convert the wave fronts of microwave radiation and can be used, in particular, in installations used to process materials with an efficiently focused radiation beam.

The purpose of the invention is to focus microwave radiation into a rectangle with a uniform intensity distribution in a rectangular beam section in the focal plane.

For this purpose, in the device for focusing, made in the form of a reflecting element, the reflecting element is made in the form of a mirror, the shape of the surface of which is determined by the system of two equations / a a (y), (x, y),

where y, y are the coordinates of a point in the rectangular coordinate system with the origin at the center of the mirror, the axis OX of the parallel focal plane, and the axis OY perpendicular to the beam incident on the mirror; and (y) - angle

ipe,

Ie 1 / S

the slope of the tangent and the curve formed by the section of the plane, perpendicular to the axis OX of the mirror at the point with the coordinate y determined from the ratio

co5 2 (| -2oc (Cit1 (y

w-y (

19 (| -2 ((D}

p (y) is the angle of incidence of the beam on the mirror in the OXZ plane,

p (y) arctg (-j);

g is the coordinate along the axis OZ, which coincides with the direction of the beam; R (z) is the radius of curvature of the wave front of the wave,

WITH

WITH

x |

GO 4

ABOUT

ON 4

 + (n) 2-W (z) W0 / 1 Y-A | 2 W0 - W (o):

 7TW0 /

I is the wavelength of the radiator; S is the distance from the origin to the focal plane;

I (V) -I (o, y, d),

I (x, y, z) is a function of the intensity of the Gaussian beam, which is defined by the expression

I (x, y, z) 10 exp (+ U2

), 10 const;

W (Z-) exP

tfr2

VD

W (zX

d is the distance from the radiation source to the origin of coordinates.

J5tW (z)

1 2a

2a, 2b are the dimensions of the rectangular section of the beam in the focal plane;

P (x, y) is the angle of inclination of the tangent to the curve formed by the section of the surface of the mirror by a plane, perpendicular to the axis OY, determined from the relation

/ (x, y) arctg

x / (1-) d + (x);

f (x) is the angle of incidence of the beam on the mirror in the OXZ plane,

| © - (. O, d),

Mr. J7TW (Z)

u- 2b.

In Fig.1 schematically shows the proposed device, working on the reflection.

Mirror 1 is located at a distance d from the source 2 and forms in the focal plane located at a distance S from the center of the mirror and perpendicular to the direction of propagation of the reflected radiation, section 3 of uniform intensity distribution in the form of a rectangle with sides 2a and 2b.

For a Gaussian beam, the wave function at an arbitrary distance can be written in the form (3)

Wo (j (x, ij, z) (| П-Т777Г exp - | kz

-Az

I r 2

e pl-fe)

one

 2 2

where r v x + y is the distance from the center of the beam to the point (x, y);

K - projection of the wave vector on the axis oz;

(° ° - o) const.

Since, in formula (1), the first exponential factor characterizes the plane wave phase and the wave front curvature, the second the intensity distribution in the beam cross section, the intensity function of the Gaussian beam in any plane perpendicular to the direction of propagation can be represented as

I (x, y, z) 10 exp (- y). w (o

(2)

Where

lo const.

Consider the reflection in the X 0 plane. To obtain an equal intensity of the reflected beam, the condition

I (vl

  Ci const

(3)

dy where I (y) I (o, y, d),

dU is the width of the wave front, in the focal plane, reflected from the surface of the mirror, the projection of which on the OY axis is equal to dy.

In order for the power to be uniformly focused within the geometrical dimensions of one of the sides of the rectangle, equal to 2a, it is necessary that

WITH,(-). “,

aw (z)

The value of d U / dye formula (3) is determined from geometric considerations (see Fig.2) as

  tga (y) + (S + y) x x tgg-2a (y) + p (y)).

(five)

55 30 35 40

d u

45

50

Substituted the expression (5) dl in usd y

(1), we get

-Vlybigd-eec t y - C- -

 C052 ((

Or for cr iyj

ow2 (| -2ob (+ cr (y)

((y) ai ((4cf (. ((t}

This ordinary differential equation is solved by the Euler method with the initial condition

"(O) f (7)

Now consider the mapping in the plane Y 0. Similarly, the reasoning can be written

1- (S + y) tg (2 / (x, y) -p (x) j, (8)

where dV is the width of the wave front, in the focal plane, reflected from the area

element, the projection of which on the axis OX is equal to dx.

Taking into account this condition, as well as the condition of equal intensity along the x coordinate, similar to condition (3), we obtain l (x)

1 (s + y) Tx-tg (2 / (x y) (x)

 C2.

It is also obvious that c.J5rW (z)

L22b.

(9

(ten

From the relation (9) we find the expression for determining / (x, y)

Ј (x, y) | arctg

x / () (x); (eleven)

The parameters ft (x, y) and a (y) completely determine the curvature of the surface of the reflecting element.

Figure 1 - shows the proposed device, working on the reflection; Fig. 2 is a diagram of a beam transformation by the surface of a mirror; FIG. 3 is a schematic representation of the proposed device.

The proposed device is a reflecting element made in the form of a mirror 1 located at a distance (S) to the focal plane (object surface), perpendicular to the direction of propagation of reflected radiation, with rectangle 3 on which focusing is performed.

The reflecting element of the proposed form, which solves the problem of focusing microwave radiation into a rectangle, can be produced by various currently existing technological methods (for example, mechanical, ion etching, methods of creating self). In the manufacture of these reflecting elements, it is necessary to ensure a sufficiently high accuracy, which requires the use of modern technology, especially in mechanical manufacturing.

The proposed device works as follows.

The reflecting element converts the beam of radiation incident on it into reflected radiation, providing the required focusing process in the focal plane.

As an example of a device for focusing microwave radiation into a rectangle, the shape of the surface of a mirror for processing surface protective

films gyrotron radiation millimeter range.

Claims (1)

Apparatus of the Invention A device for focusing microwave radiation into a rectangle containing a reflecting element and a source of radiation, which, in order to ensure uniform distribution of intensity in a rectangular section 10 beam in the focal plane, the reflecting element is made in the form of a mirror with the shape of the surface defined by the system of equations / а а (у), 15 (x, y), where y, y are the coordinates of a point in the rectangular coordinate system with the origin at the center of the mirror, the axis OX of the parallel focal plane, and the axis OY perpendicular 20 to the beam incident on the mirror, and (y) is the angle of inclination of the tangent to the curve formed by the section of the plane perpendicular to the axis OX of the mirror at the point y coordinate determined from the relation 25 cos (| -2oc (W) (- v 3 (+ N () 4h), ( P (y) Angle of beam incidence on a mirror in the OYZ plane, ts; v (y) arctg (f); 2 - coordinate along the axis OZ, coinciding with the direction of the beam, R (z) is the radius of curvature of the wave front, 40 R (2, Z (1 + () h W (z) W0 / 1 +/- iЈ- W (o);  L l / o / I is the wavelength, radiation, S is the distance from the origin to the focal plane; I (y) (o, y, d), where I (x, y, z) is a function of the intensity of the Gaussian beam, defined by the expression 502, 2 I (х, у, z) 10 exp (- Ц-У-), I0 const; (z) d is the distance from the radiation source to the origin; 55fl j5rW (z) U 2 and 2a, 2b are the dimensions of the rectangular section of the beam in the focal plane; P (x, y) is the angle of inclination of the tangent to the curve formed by the section of the surface of the mirror by the plane perpendicular (x) The angle of incidence of the beam on the mirror in OXZ plane OY axis, determined from the relation (x, y) | arctg I (1-Hi)) df + -lp (x); I © I (Ј o, d), vЈfW (z) 2b C2 I © I (Ј o, d), vЈfW (z) 2b C2 ua / Editor M.Vasilyeva Compiled by V.Detkov Tehred M. Morgental Fig.Z Proofreader E. Lonchakova