JPH03503141A - Device for generating focused shock waves - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Device for generating focused shock waves [Field of invention] The present invention relates to applied physics, and in particular to devices for generating focused shock waves in transparent media. do. This is used in machine building, tool making, chemical engineering, and for generating local voltages. It is used in other fields of application such as medical treatment when used for diagnostic and non-surgical lithotripsy purposes. It becomes very important in science.

[Background of the invention]

The ability to apply a focused shock wave to a specific point on an object depends on the amplitude of the shock wave, the focusing unit's It is a function of multiple factors such as the configuration and output variables of the laser used, and this function includes It also includes the accuracy of the focusing of the shock wave, which is determined by the type of optics used at the site.

In particular, the more complex the optical system designed to focus the shock wave, the more Generally speaking, the greater the number of non-integral optical elements that make up an optical system, the better the performance of the device. rotation and adjustment becomes difficult. This means that any relative displacement of the optical elements will affect the focusing of the device. This is to cause a shift and make it impossible to focus the shock wave at a specific point.

Devices for generating focused shock waves are well known in the art; Means for generating spherical shock waves designed in the form of a spark discharger, and an elliptical tip It has a means to focus these truncated waves. both of these Both means are immersed in the fluid, and this spark discharger is located at the first focus of the ellipse ( West Germany, Application No. 3210919. DB, A.

3210919).

In operation, a spark discharge occurs at the first focus of the ellipse in which the spark discharger is located. The spherical shock wave generated in the fluid is reflected by the elliptical surface and focused at the second focal point. It will be done. However, the generation of shock waves and their focusing must be done by two separate bodies. Since the optical system used in the target device is It is complicated. In other words, operating and adjusting the device is quite difficult, especially when one side is spherical. Two fixed points, one being the point of shock wave generation and the other being its convergence point. The use of an elliptical reflector with a focal point of Accurate adjustment is always required. However, during operation of the device, the electrodes of the spark discharger burns out more and more, causing a movement of the spark discharger relative to the focal point of the ellipse. This is it The initial shock wave is distorted, making it impossible to focus on a specific point.

Furthermore, the use of spark dischargers as a means of generating shock waves is especially useful for medical purposes. This is undesirable in devices, etc., as it is dangerous to both the operator of the device and the patient.

Devices for generating focused shock waves are also known, such as pulsed lasers, liquid a chamber filled with spherical shock waves, and a chamber placed within the chamber to focus the laser beam and focus the spherical shock wave. (PCT/DE 85103631). This means two non-integral elements separated from each other, e.g. a parabola for focusing a laser beam Face mirrors and truncated ellipses whose surfaces are adapted to focus spherical shock waves The focal point of the parabolic mirror is one of the focal points of the truncated ellipsoid. It is necessary that the

Focusing of the laser radiation can also be done using a Fresnel lens, or some It is also possible to use a combination of methods.

Compared to previous technical solutions, in this device the generation of spherical shock waves is The medium generated at the focal point of the laser beam, which is made to coincide with one focus of the circle, It is carried out by optical destruction of the body.

Focusing of the spherical shock wave is achieved by reflection of the shock wave on the surface of the ellipsoid, similar to the device described above. This is done to become the second focal point of the ellipsoid. In other words, to generate a spherical shock wave The focusing of the laser beam and the focusing of this spherical shock wave are achieved by The optical system used in such devices is also It's quite complicated. As previously mentioned, such a complex optical system is important for the operation and There is a problem with adjustment.

Because some non-integral elements for focusing the laser beam and spherical shock wave Even small movements caused by defocusing the device and directing the spherical shock wave to a specific point on the object. This is to make it impossible to focus.

Furthermore, the focal point of the shock wave focused on one of the focal points of the ellipsoid is located within the laser radiation region. When using the device during treatment, there is a risk of exposing the patient to gold laser radiation. This poses a risk of radiation and requires a shield to protect the patient from this radiation. This results in a considerable reduction in the energy of the shock wave.

[Summary of the invention]

The main purpose of the invention is to focus the laser radiation to ensure the generation of a spherical shock wave and to A means for focusing a spherical shock wave is provided that focuses the laser radiation and the sphere by a single element. A device for generating focused shock waves that is designed to enable focusing of surface shock waves. The goal is to provide a This simplifies the optical system of the device and makes its operation and Adjustment is also simplified and the accuracy of shock wave focusing is improved.

To achieve this primary objective, devices for generating focused shock waves are a cell with a medium transparent to the laser radiation; and a cell with a medium transparent to the laser radiation. and means for focusing the spherical shock waves and having a surface for focusing the spherical shock waves. According to the invention, the means for focusing the laser radiation and the spherical shock wave are A concave and convex lens shape with a surface of different curvature made from a material transparent to radiation The surface that focuses the spherical shock wave is concave.

In the proposed device, the laser beam is focused on a material that is transparent to the laser radiation. The spherical shock wave is focused by the concave and concave lens made of It is done. That is, the focusing of the laser radiation and the focusing of the spherical shock wave are performed by a single element. will be held.

As a result, the optical system used in this device is based on patent PCT/DB85103631. The optical system of the device described in the specification is simpler and this reduces the possibility of defocusing. The operation and adjustment of the fruiting device is simplified.

According to the findings of the inventor, it is possible to focus a laser beam and a spherical shock wave. In order to do this at the same time, the surface of the lens needs to have different curvature values. , the ratio of the curvature of the lens surface determines the relative position of the focal point of the laser radiation and the focal point of the shock wave. I have decided.

As a result, in this device, interchangeable lenses with different ratios of surface curvature This makes it possible to use a set of laser radiation focal points and shock wave focal points. It becomes possible to change the relative position with the bundle point. Therefore, the operation of the equipment should be becomes easier.

According to an embodiment of the invention, the concave surface of the lens faces the laser and the convex surface is coated to reflect laser radiation.

In this example, the laser beam is focused by the convex reflective surface of the lens and is spherically The surface shock wave is focused by the concave surface.

The focal point of the spherical shock wave is located between the laser and the lens.

In other embodiments of the invention, it is the convex surface of the lens that faces the laser.

In these conditions the focus of the laser radiation is on the lens, i.e. on both surfaces of this lens. The convex and concave surfaces, and the medium that separates them, are used to focus the spherical shock wave. is performed by the concave surface of the lens.

The focal point of the spherical shock wave is on the side of the lens opposite to the laser.

These two embodiments of the device for generating focused shock waves solve the problem and From this point of view, they are the same. In other words, the focusing of the laser radiation and the focusing of the spherical shock wave are the same. The point is that it is performed using one optical element. However, during operation, the focal point of the shock wave is The difference is that the laser and the lens are in different positions, which causes Different fields of application are possible as in the embodiments.

In any of the proposed embodiments of the invention, the principal optical axes of the convex and concave surfaces are mutually It may be at a certain angle.

Because of this relative position of the principal optical axis on the lens surface, the focal point of the shock wave is directly aligned with the laser radiation. It is now possible to be outside the region of Laser protection can be easily performed without the need for laser protection.

Due to the latter fact, a device for generating focused shock waves designed on the basis of this example can be made suitable for use in medical purposes.

[Brief explanation of the drawing]

The above-mentioned advantages and features of the invention will be explained in the following details of a preferred embodiment with reference to the accompanying drawings. This will become clearer from the detailed explanation.

Figure 1 shows an example in which the convex surface of the lens is coated to reflect laser radiation. FIG. 3 is an optical path diagram illustrating a device for generating a focused shock wave according to an example.

Figure 2 shows the light produced when the principal optical axes of the lens surfaces are tilted at a certain angle with respect to the apparatus shown in Figure 1. Road map.

FIG. 3 shows an apparatus for generating focused shock waves designed according to another embodiment. Optical path diagram.

[Best mode for carrying out the invention]

With reference to Figure 1.2.3, according to the invention (device for generating focused shock waves) consists of a pulsed laser 1, a box 2 filled with a medium that is transparent to the laser radiation, and in the box 2 and provided with means 3 for focusing the laser radiation and focusing the spherical shock wave. Ru.

For example, box 2 is made in the form of a tank filled with a liquid or gas that is transparent to the laser radiation. It is. Means 3 for focusing the laser radiation and focusing the spherical shock wave can be of different curvatures. It is a concave-convex lens having a concave surface 4 and a convex surface 5 expressed by a ratio value. Lens 3 is made of a material that is transparent to laser radiation.

The concave surface 4 is here adapted to focus the spherical shock wave. Focusing laser radiation The focusing point OI of the lens 3 (Fig. 1.2.3) is located in front of the concave surface 4. There is. The surfaces 4 and 5 are made, for example, in the form of a sphere. These surfaces 4 and 5 can be a different curved shape such as an ellipsoid, but a spherical shape is easier to manufacture. I think that the. According to a first embodiment of the invention shown in FIG. The convex surface 5 is coated with a coating 6 to reflect the laser beam. The coating is, for example, silver plating. Focus point 01 of laser radiation is located between the laser 1 and the concave surface 4, and the focal point Ot of the spherical shock wave is located between the laser 1 and the concave surface 4. 1 and the lens 3, and the convergence point 0 of the spherical shock wave from the concave surface 4 of the lens 3. The distance to □ is determined by the ratio of the curvatures of surfaces 4 and 5 of lens 3. lens 3 If surfaces 4 and 5 of are spherical, this distance can be calculated from the following equation:

However, in the formula, R+ = convex surface 50 radius of curvature expressed in m units, R, = concave surface 40 expressed in m units Radius of curvature, γ””nl/nz, where nl and R2 are transparent medium and lens is the refractive index of each of the materials in lens 3, L=average thickness of lens 3 expressed in m, d=concave surface 4 of lens 3 and collection of shock waves Distance between bundle points O3 expressed in meters.

Relational expression (1) is Abbe's equation for refraction and reflection of a beam on the spherical surface. derived from relations regarding invariants (G. S. Landsberg, rOptika '1976, Nauka (Moscow), P, 926), Lens 3 The refractive index n and the refractive index n1 of the transparent medium in which the shock wave is generated are also taken into consideration.

When the surfaces 4 and 5 have an aspherical shape that is close to a spherical surface, the above condition (1 ) remains valid as is, in this case R.

and R2 is taken as the average value of the curvature of surfaces 5 and 4. For example, an ellipsoid-like table Due to the different shapes of surfaces 4 and 5, the distance d from concave surface 4 to the focal point Ot of the shock wave is , a well-known technique (Metody rasch by G, G, 51usarev) eta opticheskikh 5istesB +193’L 0NT1 ．． Glavnaya redaktsi fizikoteoretiche skoiliteratury (Leningrad-Moscow), p. , 577).

Therefore, in such a device, the curvature of surfaces 4 and 5 is intersecting and exhibits different ratios. It is now possible to use a combination of interchangeable lenses 3, which reduces the impact of shock waves. Different positions of the focus point 0- are obtained, which simplifies the operation of the device. Laser beam and opposition To focus the bombardment waves simultaneously, the lens is made from a material that is transparent to the laser radiation. The interface between the concave surface 4 of the lens 3 and the transparent medium must be sufficiently protected against shock waves. Must have a high reflection coefficient. Such a material can form a transparent medium and a lens 3. Each of the solids made is characterized by the wave resistance ZI and Zt, and the wave resistance is calculated by the following formula: are related to each other.

However, in formula (2), σ, = proof stress of the lens material expressed in N/rrf units, P, = N/rrf units The pressure amplitude in the shock wave at the interface between the transparent medium and the lens is expressed as .

Z1 = ρICI, Z2 = ρZCZ ... (3) However, formula 3) In, R1 and R2 are those of the transparent medium and lens material expressed in kg/rrf. The density of each C3 and C2 are the respective acoustic velocities in transparent media and solids expressed in m/s degree, and the particular minimum value of the reflection coefficient of the shock wave is expressed in the form of intensity.

When condition (2) is solved for the wave resistance Zl of the solid, it becomes (4).

In this way, for any transparent medium (liquid or gas), the parameter σ1 ．． ρ1. ρ! Using a table with data regarding +CI and C3, set each condition. It is possible to indicate several materials that meet (3). First of all, the lens The impact of the shock wave on 3 does not cause any damage to the lens. This is the pressure wave amplitude is lower than the plasticity threshold of the solid. Second, the shock wave focusing efficiency is extremely high. This is because it is expensive.

Lens 3 is made of lead glass or quartz glass, for example.

Proposed for applications such as medicine where the effects of laser radiation on the object can be avoided When using the device, the principal optical axes of the concave surface 4 and convex surface 5 must be tilted to each other. , the focal point 0□ of the shock wave is located away from the laser radiation path, and that point is It can be shielded to protect it from laser radiation.

FIG. 2 shows a device for generating focused shock waves, in which five reflecting surfaces 5 are used. The main optical axis is located on the optical axis of the laser 1, and the main optical axis of the concave surface 4 is with respect to the laser 1. It is located at an angle. The inclination of the optical axis of the concave surface 4 with respect to the principal optical axis of the convex surface 5 is In particular, the structure of the device, etc. should be considered to give maximum consideration to the placement of the object, which is the patient. selected.

FIG. 3 illustrates another embodiment of the invention, in which the convex surface 5 of the lens 3 is facing the user 1.

The focal point 01 of the lens 3 for focusing the laser radiation is the same as in the first embodiment. Similarly, on the side adjacent to the concave surface 4 of the lens 3, the focal point 03 of the shock wave is the laser 3 It comes to be located on the side of lens 3 opposite to . A certain characteristic from the concave surface 4 of the lens 3 In order to focus the shock wave at the position, if surfaces 4 and 5 are spherical, the following equation must be satisfied: It is necessary to

However, in the formula, Rt is the radius of curvature of the convex surface 5 expressed in m, and R2 is expressed in m is the radius of curvature of the concave surface 4, T is n1/nz, and n and n2 are the respective refractive indices of the transparent medium and lens material, L is the average thickness of the lens 3 expressed in m units, and d is expressed in m units. It is the distance between the concave surface 4 and the focal point 02 of the shock wave.

Similar to the previous example, the above relationship is based on Atsbe's impairment for refraction and reflection at the spherical surface. Obtained from the relationship between variables.

Due to the different shapes of the surfaces 4 and 5, the distance d from the concave surface 4 to the focal point 02 of the shock wave can be determined by a well-known method similar to the first example (GJ, 51 usare). v authorMetody rascheta opti-cheskikh si stew” + 1937 + 0NT1. Glavnaya r edaktsiaftziko-teoreticheskoi l1ter atury (Leningrad-Moscow).

P, 577).

Means 3 for focusing of laser radiation and spherical shock waves as illustrated in FIGS. 1 and 3 The example solves the problem of focusing laser radiation and shock waves using a single element. The optical system of the device for generating focused shock waves can be simplified and its operation improved. It will be obvious to those skilled in the art that rotation and adjustment will be simplified. any place Even in the case of laser radiation and shock waves, laser radiation and shock waves are focused. The light is focused by a concave-convex lens 3 having a concave surface 4. The foregoing embodiments of the invention are the same. etc. Therefore, all considerations regarding the material for making the lens 3, and the convex surface 5 of the lens 3. Regarding the inclination of the main optical axis (Fig. 2) of the concave surface 4 with respect to the main optical axis and the device of the first embodiment, All the possibilities of using the combination of lenses 3 mentioned above are also shown in Fig. 3. It is possible.

Various embodiments of the device for generating focused shock waves according to the invention Specific values for the parameters are shown below.

A device for generating focused shock waves as shown in Fig. 1.

ruby crystal laser, 1 peak radiant energy EI O, 2J, - pulse length r 15 -20nS.

Transparent medium - Coro distilled water H80, -Refractive index n+ 1.33, -density ρI 1 03kg/Po, -Sound velocity Cr 1.43X103m/s, -Wave Resistance Z 11.43xlO’kg/(I・s) The concave surface 4 of the e lens 3 is The convex surface 5 is coated with a reflective coating.

Materials for making lenses - quartz glass, -Refractive index n Z N, 51, - density ρ, 2.5　X10”kg/I, -Sound velocity　Ct　　　　　　　　5.6　X10 ”m / s, - wave resistance Z z 14xlO’kg / (rr f-s), - Yield strength of lens material σt 7.8 X10'N/a, - Convex surface Radius of curvature R+ 6X10-”m, -radius of curvature Rz of concave surface 2.2 Xl0-”m.

-Average thickness of lens L 0.2Xl0-”m.

The laser radiation is directed to a focal point at a distance of 2.7 Xl0-" m from the concave surface 4 of the lens 3. 0. focused on. A spherical shock wave is generated at point 0. A point Ot, at a distance of 4 to 5 m from That is, from the concave surface 4'2. ．． A point at a distance of 3 x 104m or 2.2Xl0-”m focused on. Parameter E1. Depending on the specific values of τ, RI, and Rt, the liquid ( Pressure at the interface between Coro-distilled water H20) and a solid (quartz glass used for lens 3) The force P0 reaches 106N/rd.

The apparatus for generating the focused shock wave of FIG.

ruby crystal laser, -Beak radiant energy EI 0.2J.

-Pulse length r 15-20nS.

Transparent medium - Coro distilled water H20, -Refractive index n+ 1.33, -density ρ+ 103kg/Bo, -Sound velocity C+ 1.43X10'm/s, - Wave resistance Z + 1.43 X 10’kg/(I/S).

The convex surface 5 of the lens 3 faces the laser 1.

Lens material - quartz glass, -Refractive index n, 1.51, -density R2λ5 X10”kg/ Po, -Sound velocity Ct 5.6 X103m/s, -Wave resistance Z t 14 X 10'kg/(rrf-s), - Lens material Proof strength of material σt 7.8X10’N/rrf.

- Radius of curvature of convex surface R11,6X 10-"m.

- Radius of curvature of concave surface Rz O, 15m, - Average thickness of lens L 0.2 Xl0-”m.

In this example, the laser radiation is located 0.142 m from the concave surface 4 of the lens 3. It is focused on a certain point 01. The spherical shock wave emitted from point 0+ is caused by the concave surface 4, It is focused at point 02 at a distance of 0.16 m from this surface. specific parameter E 1. τ.

Due to R1 and Rt, the pressure P0 at the interface between the liquid and the solid forming the lens 3 is 10 ”N/n(reaches.

The operation of the apparatus of FIG. 1 is as follows.

The laser radiation entering box 2 from laser 1 hits lens 3 and enters transparent lens 3. It is reflected by the convex surface 5, which is a mirror surface, and finally reaches the point OI in the transparent medium. focused. As a result, optical damage to the medium occurs at point O1 on the side of concave surface 4 of lens 3. occurs, forming a spherical shock pressure wave. Since the concave surface 4 of the lens 3 is a focusing surface, , the spherical shock wave is partially reflected by the spherical concave surface 4, and then the laser 1 and the lens It is focused on the point 0□ between 3 and 3. In this way, the focusing of laser radiation and the spherical shock wave Focusing is performed by the same element, namely lens 3. This allows patent PCT /DE 85103631, compared to the optical system of the device described in the specification of The system becomes simpler, and operation and adjustment become easier.

The apparatus shown in FIG. 3 operates as follows.

Laser radiation is applied to the convex surface 5 of the lens 3. Lens 3 is for the laser beam. The laser beam passes through the lens 3 and is made from a transparent material. is focused by both sides 5 and 4 of focused. As a result, optical breakage occurs at that point and a spherical shock pressure wave is generated. . Since the concave surface 4 of the lens 3 is a focusing surface, the spherical shock wave is partially focused on the concave surface 4. After being reflected, it is focused at a point 02 on the side of the concave surface 4 of the lens 3 opposite the laser 1. It will be done.

Therefore, in this embodiment of the device for generating focused shock waves, the laser radiation and the focusing of the shock wave is likewise carried out by a single element, namely the lens 3. It will be done.

To change the relative position of the focal point of the laser radiation and the focal point of the spherical shock wave, use the table It is possible to use a set of interchangeable lenses 3 with different ratios of the radii of curvature of the surfaces 4 and 5. This makes the device even easier to operate.

The main optical axes of concave surface 4 and convex surface 5 (Fig. 2) are designed to be at a certain angle to each other. Lens 3 can also be used. In particular, the main optical axis of the convex surface 5 is the axis of the laser beam. They may coincide, but the main optical axis of the concave surface 4 is tilted at a certain angle with respect to it. Ru.

In this case, optical damage to the medium occurs on the axis of the laser beam, and this damage causes After being reflected by the concave surface 4, the spherical shock wave generated by Focused on 0□.

This makes it possible to shield the object from this radiation.

[Possibility of industrial use] The proposed device can be used medically for diagnostic and non-surgical lithotripsy purposes. Most useful.

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Claims (4)

[Claims] 1. Pulsed laser (1), a box (2) with a medium transparent to the radiation of the laser; adapted to focus the laser radiation and the spherical shock wave; a focused shock wave comprising means (3) having a surface (4) adapted to focus; A device for generating The means (3) for focusing the laser radiation and the spherical shock wave The surfaces (4, 5) are shaped like concave and convex lenses with different curvature values. and the surface for focusing the spherical shock wave is a concave surface. A device for generating bundle shock waves. 2. The concave surface (4) faces the laser (1) and the convex surface (5) faces the laser radiation. Claim 1, characterized in that the coating is applied to oppose radiation. The device described. 3. Claim characterized in that the convex surface (5) faces the laser (1). The device according to item 1. 4. The principal optical axes of the concave surface (4) and the convex surface (5) are at certain angular positions relative to each other. 4. A device according to any one of claims 1 to 3, characterized in that: