# Method of varying neck diameter of output laser beam at fixed distance from laser

FIELD: physics.

SUBSTANCE: method of varying neck diameter of an output laser beam at a fixed distance from the laser is realised by a device having a laser which emits a beam with neck diameter 2hp1 and a confocality parameter zk1, a two-component optical system which forms, in the initial position of components, an output neck with diameter $2 h p 20 '$ at a distance L0 from the laser, each component of the optical system being capable of moving along an optical axis. Matched displacement of components is carried out along the optical axis according to the law s2(s1)=a·y(s1)-Δ0+s1, where: s1 and s2 are displacements of the first and second components of the optical system; $a = f 1 ' 2 / z k 1 ;$ Δ0 is the distance between the rear focus F2 of the first component and the front focus F2 of the second component in the initial position. Parameter y is determined by solving the cubic equation $a 2 ( x 2 + 1 ) y 3 + a [ 2 a x − b ( x 2 + 1 ) ] y 2 + [ a ( a − 2 b x ) + f 2 ' 2 ( x 2 + 1 ) ] y + x f 2 ' 2 − a b = 0,$ where $x = z p 10 − s 1 z k 1 ;$ $b = z p 20 ' + Δ 0 − s 1 ;$ zp10 is the position of the neck of the input beam relative the front focus F1 of the first component in the initial position; $z p 20 '$ is the position of the output neck relative the rear focus $F 2 '$ of the second component in the initial position; $f 1 '$ and $f 2 '$ are the back focal distances of the components.

EFFECT: enabling formation of a laser beam with a variable neck diameter at a fixed distance from the laser.

4 dwg

The invention relates to a laser technique to the field of optical systems, which converts laser radiation, and can be used in engineering, medicine, instrumentation, optical communication and other fields of science and technology, particularly where it is necessary to form the waist of the beam with a variable diameter at a fixed distance from the laser.

The level of technology

There are various methods of forming the laser beam with variable parameters.

There is a method of changing the position of peredachi laser beam, in which the longitudinal movement of the focusing lens by a set of piezoelectric elements, which is implemented in the device . The use of the device in a limited range only change the position of the waist of a beam of constant diameter. Its disadvantage is the inability to change the diameter of the waist of the output beam. This is because the device uses a special case of conversion of the laser beam focusing lens, when at its input quasiparallel beam with very remote strangulation. In this case, there is a very weak dependence of the diameter of the output of the banners from the position of the focusing lens, which allows to consider the diameter of the constriction is almost constant.

Also known the way the move is of the banners of the output laser beam of constant diameter $2hp2'=2hp1α$ =const), implemented in the device , containing a laser emitting a beam with a waist diameter 2hp1and two movable optical component.

The disadvantage of this method is the inability to change the diameter of the waist of the output beam.

The closest in technical essence and the achieved result is the way the permanence of the position and diameter of the output spot upon small variations in the diameter of the entrance banners. This method is implemented in the matching of the laser optical system comprising sequentially installed laser emitting a beam with a diameter banners 2hp1and parameter confocality zk1two-component optical system, each component of which (representing a lens or set of lenses) can move along the optical axis .

However, this method does not allow you to change the diameter of the waist of the output beam, which limits its scope.

Disclosure of inventions

The task of the invention is to develop a method that provides a change in the diameter of the output banners at a fixed distance from the laser.

what does is solved by that way change the diameter of the constriction of the output laser beam at a fixed distance from the laser, which is realized by a device, comprising sequentially installed laser emitting a beam with a diameter banners 2hp1and parameter confocality zk1two-component optical system forming in the initial position of the components of the output waist diameter of$2hp20'$ at a distance of L0from the laser, each component of the optical system has the ability to move along the optical axis, carry out concerted movement component along the optical axis according to the law s2(s1)=a·y(s1)-Δ0+s1where s1and s2- move the first and second components of the optical system, respectively, where Δ0- the distance between the rear focus$F1'$ the first component and the front focus F2the second component in the initial position of the components of the optical system; the parameter is determined from the solution of the cubic equation

$a2(x2+ 1)y3+a[2ax-b(x2+1)]y2+[a(a-2bx)+f2'2(x2+1)]y+xf2'2-ab=0,$ where$x=zp10-s1zk1;$ $b=zp20'+Δ0-s1$ ; zp10the position of the waist of the input beam relative to the front focus F1the first component in the initial position of the components;and$zp20'$ the position output of the constriction relative to the back focus$F2'$ the second component in the initial position of the components of the optical system.

Brief description of drawings

Figure 1 shows the scheme of a two-component laser-optical system;

figure 2 presents a two-component laser-optical system for changing the diameter of the waist of the laser beam at a fixed distance from the laser;

figure 3 presents the law of the moving components of the laser-optical system;

figure 4 presents the law of variation of the diameter of the output of the banners from the magnitude of the displacement of the first component of a two-component laser-optical system.

The implementation of the invention

The invention consists in using two-component laser-optical system, components of which move on the non-linear law, which provides a constant distance from the original banners laser to the output of the banners and the change in the diameter of the output of the banners. The law of transfer of components takes into account the distinctive properties of laser radiation from the classical radiation and the dependence of the conversion of laser radiation optical elements and systems.

Based on the properties of laser beams and simple mathematical relationships between the parameters of the beam at the input and output DOHC nonintel LOS and its design parameters, the ratio for diameter$2hp2'$ provisions (defocusing)$zp2'$ banners of the output beam relative to the back focus of the second component and the length L LOS (length from input to output banners) have the form 1 :

$2hp2'=2hp1α,zp2'=(zp1+Δzp12+zk12f1'2)α,the (1)L=-zp1(1-α)+Δ(1+αzp12+zk12f1'2)-sF1+t1+sF1''-sF2+t2+sF2''.$ Here longitudinal increase in two LOS; 2hp1and zk1- the diameter of the constriction and the parameter confocality the beam at the entrance of a two-component system; zp1position (fussing) waist of the input beam relative to the front focus F1the first component;and$zp2'$ position (fussing) waist of the output beam relative to the back focus$F2'$ the second component; Δ is the distance between the foci$F1'$ and F2components;and$f1'$ and$f2'$ back focal length of the components;and$sF1$ and$sF2$ - the front focal segments of the first and second component, respectively;and$sF1''$ and$sF2''$ - rear focal segments of the first and second component, respectively; t1and t2- the thickness of the components of the optical system.

The design parameters of the LOS are$f1',$ $f2',$ zp1and Δ. Formally free parameters are zk1and 2hp1. However, for laser light sources they are uniquely related to the invariant laser radiation $JlandC=hp12/zk1=M2λ/π$ which is uniquely determined by the wavelength λ and the quality parameter M2the laser beam. Both of these options are is acceptable, because prior to the development of optical characteristics of the laser radiation at the entrance of LOS known.

Optical device for a continuous change in the diameter of the waist of the laser beam includes sequentially and coaxially located with the laser source, two LOS, the law of movement which takes into account the parameters of the laser beam and LOS and is determined taking into account the relations (1). When dimensioning LOS, providing the required values of$2hp2'$ ,$zp2'$ and L, the number of free design parameters equal to 4. Therefore, it is always possible to choose the design parameters of the LOS, in which is formed an output beam with the required specified parameters, while providing the necessary diameter of the constriction and the radiation power density in its cross-section. Moreover, the available freedom in the choice of law travel component is used for the constancy of the distance L between the laser and the output strangulation. In this device there is no need for time-consuming change the configuration of LOS and the alignment of its nodes. While the implementation of longitudinal displacement of the optical components is th system is not difficult.

Because when passing through LOS invariant of the laser beam remains$JlandC=hp12/zk1=hp2'2/zk2'$ for the size of the banners and parameter confocality output beam is just the ratio of$hp2'2/zk2'=M2λ/π.$ So if you change the diameter banners$2hp2'$ the output beam is changed and the parameter confocality$zk2'$ that determines the overall length of banners$2zk2'$ the output beam.

The device includes a laser 1, a radiation beam which h is by the wavelength λ, shifting 2 diameter 2hp1located at a distance of d0from the output end of the laser parameter confocality zk1the parameter M2LOS consisting of the first 3 and second 4 moving components, which forms the waist 5 of the laser beam with a diameter of$2hp2'$ (see figure 2). The system length L (the distance from the source to the output banners) is constant.

Continuous change in the diameter of the output waist of the laser beam with a fixed position of the output section of the constriction due to the longitudinal displacement of the LOS components is possible only under certain conditions. These conditions establish a definite link design parameters of LOS and beam parameters of the laser source. She, in turn, determines the displacement of the LOS components. Therefore, for the selected laser source with a known radiation parameters to solve this task allows the optical system, with well-defined structural parameters, the components which are moved according to the agreed law.

A feature of the invention is to use the transformation laws of the laser beam optical elements and systems, analytical St. the bond between the parameters of the laser beam and converts it to a two-component optical system and obtaining conditions ensure the immobility of the output banners with variable longitudinal increase in LOS. Received communication allows you to change the diameter of the waist of the output beam at a fixed distance from the waist of the input beam.

In the initial (zero) position, the design parameters LOS: back focal distance of the first$f1'$ and the second$f2'$ component, the position of the cross section of the waist of the laser beam relative to the front focus F1the first component of zp10and the distance Δ0between the rear focus$F1'$ the first component and the front focus$F2'$ the second component is chosen to ensure that:

1) is a longitudinal increase in$α0=(2hp20'/2hp1)2$ where$2hp20'$ - the diameter of p is retzke output beam in the initial position of the LOS components,

2) given the length of the system

$L0=-zp10(1-α0)+Δ0(1+α0zp102+zk12f1'2)-sF1+t1+sF1''-sF2+t2+sF2''.$ When these conditions are met, you must also ensure the physical feasibility LOS, when in the initial position of all components of the longitudinal distance is positive: from the input banners to the first surface of the first component$d10=-zp10-sF1$ from the last surface of the first component to the first surface the second component of $d20=sF1''+Δ0-sF2$ from the last surface of the second component to the output banners$d30=sF2''+zp20'.$ In the last ratio of$zp20'$ the position output of the constriction relative to the back focus$F2'$ the second component in the initial position of the components.

The design parameters of the LOS in the initial position of the components are original data to determine the law of displacement components, which changes the diameter of the waist of the output beam at a fixed distance from the waist of the input beam. For this components you want to move on nonlinear law s2(s1):

s2(s1)=ay(s1)-Δ0+s1,

where the value of y is the C the solution of the cubic equation

$a2(x2+1)y3+a[2ax-b(x2+1)]y2+[a(a-2bx)+f2'2(x2+1)]y+xf2'2-ab=0;$ $a=f1'2zk1;$ $x=zp10-s1zk1;$ s1, s2the amount of movement of the first and second components LOS;$b=xzk1+zp20'+Δ0 -zp10$ .

For current provisions of the LOS components of the optical interval Δ(s1)=Δ0-s1+s2and$d1(s1)=-zp10+s1-sF1$ ,$d2(s1)=sF1''+Δ-sF2$ ,$d3(s1)=sF2''+zp2'.$ The displacement of the second component s2is found from the solution of the above equation for a given displacement of the first component, s1. This cubic equation can have one or three real roots. In the case of the three roots is chosen such the root, which corresponds to the lower plumage is edenia second component.

In the intermediate position of the longitudinal components increased LOS and the diameter of the output banners are determined by the expressions: $α(s1)=(f2'/f1')2(1+xy)2+y2,$ $2hp2'(s1)=2hp1α(s1)$ .

The differential linear increase of VOC is equal to:$M=(2hp2max'/2hp2min')2,$ where$2hp2max'$ /maths> and$2hp2min'$ - maximum and minimum diameter of the output banners throughout the range of movement of the components.

Implement the method as follows (figure 2). The laser beam 1 with hauling 2 diameter 2hp1sequentially converted components 3 and 4 of the optical system which is formed hauling 5 with a diameter of$2hp2'$ . Due to the longitudinal displacement of the components of the optical system according to the law s2(s1) ensures the invariance of the distance between the waist 1 input and hauling 5 of the output beam on the entire range of movement of the components and the change of the diameter of the output beam waist.

The preferred option (example) of the invention for changing the diameter of the waist of the beam from 0.32 mm to 0.08 mm at a fixed distance L=452,75 mm from the laser using laser YAG:Nd3+(λ=1.06 µm, M2=1,05, 2hpl=0.3 mm) is shown below.

The design parameters of the two-component VOC in the initial position of the components have the values given in the table.

 The radii of curvature of the refractive surfaces of the components, mm Air gaps and the thickness of the lens, mm The refractive index of the medium at the wavelength λ 82,47 1 (air) 56,32 1K 3,40 1,7277 (TV) -100,15 185,54 1 (air) 56,87 2K 4,04 1,5062 (K8) -137,37 177,30 1 (air) α01,17, L0=452,75 mm

Figure 3 presents a plot of the displacement components calculated VOC's, and figure 4 is a plot of the changes in the diameter of the output of the shifting movement of the first component.

Sources of information

RF patent 2413265, IPC G02B 27/16 published: 27.02.2011.

RF patent 2411598, IPC G11B 7/125, G02F 1/29, H01S 3/10, published: 10.02.2011.

RF patent 2435182, IPC G02B 27/09 published: 27.11.2011.

Pakhomov I.I., Tsibulya A.B. Calculation of optical systems of laser devices. M.: Radio and communication, 1986. 152 C.

How to change the diameter of the constriction of the output laser beam at a fixed distance from the laser, by the device, comprising sequentially installed laser emitting a beam with a diameter banners 2hp1and parameter confocality zk1two-component optical system forming in the initial position of the components of the output waist diameter of$2hp20'$ at a distance of L0from the laser, each component of the optical system has the ability to move along the optical axis, characterized in that exercise consistently moving components along the optical axis according to the law s2(s1)=a·y(s1)-Δ0+s1where s1and s2 - move the first and second components of the optical system, respectively, where Δ0- the distance between the rear focus$F1'$ the first component and the front focus F2the second component in the initial position of the components of the optical system; the parameter is determined from the solution of the cubic equation
$a2(x2+1)y3+a[2ax-b(x2+1)]y2+[a(a-2bx)+f2'2(x2+1)]y+xf2'2-ab=0,$ where$x=zp10-s1zk1$ ; $b=zp20'+Δ0-s1$ ; zp10the position of the waist of the input beam relative to the front focus F1the first component in the initial position of the components;and$zp20'$ the position output of the constriction relative to the back focus$F2'$ the second component in the initial position of the components of the optical system,$f1'$ and$f2'$ back focal length of the components.

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SUBSTANCE: the arrangement has a substrate on which there are two adjoining topologies having common axles of fractalization and a center, the modules of each of them are similar to the corresponding modules of the first adjoining topology. At that additionally on the substrate the third adjoining topology whose radius R3 of the basic circumference equals R1√3 is formed.

4 cl, 8 dwg FIELD: technical physics, possible use for expanding arsenal of devices for transformation of electromagnetic field to coherent form.

SUBSTANCE: the device contains semiconductor substrate, on which in slits self-affine topology is formed on basis of fractalizing module, consisting of a set of circles with radius R, where first circle is geometrical locus of positions of centers of other circles of the set with equal distances between adjacent circles, center of first circle coincides with the center of circle with radius equal to 2R and is the center of the whole self-affine topology, and fractalization of module occurs along axes, passing through the center of the first circle and centers of other circles of the set. Self-affine architecture is grounded.

EFFECT: creation of planar source of device for transformation of electromagnetic radiation to coherent form.

6 dwg FIELD: the invention refers to optical technique.

SUBSTANCE: the lens has in-series installed the inner down the way of radiating of light diode, and the exterior surface. The inner surface of the central zone adjacent to the axle of the lens, has an optical force providing transfer of the image of the radiating site of the light diode on more remote distance from the exterior surface. The exterior surface has a form of a funnel turning with its peak from the radiating site of the light diode. The profile of the exterior surface is such that at first interaction of radiating with the exterior surface full inner reflection takes place and at the second interaction of radiating with the exterior surface refraction of light takes place in the direction primarily perpendicular to the optical axle of the lens.

EFFECT: reduces part of the radiating flow emergent of the forming lens near its axle, increases intensity of emergent beam of light and provision of more uniform distribution of intensity of light falling on the screen.

5 dwg FIELD: optics.

SUBSTANCE: laser lighting device for lighting band or linear portion S on object B, primarily on sheet material includes source 2,2' of laser radiation, optical system 4 for expanding the beam, spatially expanding fan-shaped laser beam L2 in two mutually perpendicular directions, and also an astigmatic lens 6, upon which fan-shaped laser beam L2 falls, focal distance f2 of which is shorter than distance A from beginning of fan-shaped laser beam L2 and focal plane of which lies on object B or close to it.

EFFECT: generation of a beam on surface, with high intensiveness, with low light losses; human eyes are protected from laser radiation.

8 cl, 3 dwg 