JPH0715096A - Improved laser beam generator - Google Patents

Abstract

PURPOSE: To improve the gas-heating problem and minimize the chevron effect by providing one or more partition segments which are longitudinally disposed in a laser structure. CONSTITUTION: This laser beam generator 20 has a partition 22 in a discharge tube. The partition 22 is held at a part of the inner wall 24 of the tube 20 and disposed at a specified position in the annular structure 20, so that the thermal dispersion is like scattering, thereby solving the problem of overheating at the center of the tube. Owing to the partition disposed in the tube, an electric field applied in the tube can pierce radially, and the electric field is formed on the partition as well as outside the tube kept to a minimize chevron effect. This improves the problem of gas heating and minimizes the chevron effect.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICATION Field of the Invention Under the agreement between the US Department of Energy and the University of California (contract number W-7405-ENG-48) for the operation of Lawrence Livermore National Laboratory, the United States Government Have the right.

The present invention relates to an improved laser beam pulse generator. More particularly, it relates to a laser beam pulse generator using a metal vapor laser such as copper.

[0003]

2. Description of the Related Art A metal vapor laser using copper (hereinafter referred to as CVL) is one of metal vapor lasers excited by electric discharge. A metal vapor laser excited by a discharge is characterized in that the laser transits from an excited state to a low stable state.
The power of the laser oscillator when operating in the 5-20 kilohertz (or higher) range was increased from the milliwatt level to hundreds of watts.

The increase in power level is in part due to the increase in diameter of the CVL discharge tube.
However, as the diameter of the CVL discharge tube increases, a problem that affects the output power level occurs.

One of them is known as radial dynamics. Radial dynamics limit the generation of uniform laser pulses from the periphery to the center of the discharge vessel. This means, for example, MJKushne
r) and BEWarner, "Large-caliber copper vapor lasers: Dynamics and scaling (Large-Bore C
opper-Vapor Lasers: Kinetics and Scaling Issues
) ”(J. Appl. Phys. 54, No. 6, 1983) 2970
Page.

Due to the radial dynamics effect, the intensity of the leading edge of the laser pulse increases with time from the peripheral portion to the central portion of the discharge tube. This is,
It causes non-uniform pulses with a chevron shaped intensity pattern over time. This has a significant impact on the proper operation of all systems utilizing CVL's with high power and high repetition rate laser pulse power, which is considered to be uniform in intensity. Moreover, in high power, high repetition rate CVL systems, the generation of heat within the annular structure thermally creates a low stable laser level, further limiting the usable discharge tube diameter. Such heat generation problems further limit the desired increased high power levels of such CVL systems.

It is an object of the present invention to provide an improved laser beam pulse generator.

Another object of the present invention is to generate a laser beam pulse whose intensity is relatively uniform in cross-section (including leading and trailing edges).

Yet another object of the present invention is to avoid the problem of heat generation.

Yet another object of the present invention is to provide an improved device which allows high power and high repetition rates of laser systems.

[0011]

SUMMARY OF THE INVENTION Briefly stated, the present invention includes an apparatus for producing a series of laser beam pulses. The apparatus of the present invention includes a generally annular laser structure that produces a series of laser pulses. The structure includes means for intermittently applying an electric field radially through the structure to generate a series of laser pulses.

The structure further includes means for dissipating the heat generated at predetermined locations therein.

The structure described above produces a substantially uniform intensity pattern in the cross-section (including leading and trailing edges) of the power of each laser beam pulse over time, which is a problem in conventional systems. It further includes means for minimizing or eliminating the "chevron effect".

The device of the present invention includes one or more septum segments longitudinally disposed within the laser structure.

According to another aspect of the present invention, in the above structure, the partition can be slidably inserted into the discharge tube. This structure will be referred to as slide-in-
capability).

Other objects, advantages and novel features of the present invention will be apparent from the following description. Also, some will be apparent to those skilled in the art from the following description, or may be understood by practicing the invention. The purpose and advantages of the present invention are
It will be realized and implemented by means of the means recited in the claims and combinations thereof.

[0017]

In the laser beam generator of the present invention, a plurality of barrier ribs arranged at intervals in the longitudinal direction are formed inside the annular discharge tube, and an electric field penetrating the annular structure in the radial direction is formed. It is applied intermittently to generate a series of laser pulses.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the improved laser beam generator of the present invention will be described in detail below with reference to the accompanying drawings.
The drawings illustrate preferred embodiments of the invention, and together with the description provided herein, serve to explain the principles of the invention. The present invention is
Although described below in connection with the preferred embodiments, it should be understood that the invention is not limited to these embodiments. All changes, modifications and equivalents included in the spirit and scope of the invention described in the claims are included in the present invention.

FIG. 8 is a sectional view of the laser beam discharge tube 10. The discharge tube 10 shown in FIG. 8 is conventional, and details thereof are not shown except for some general explanations. As used herein, the term "chevron effect" is used to describe the occurrence of non-uniform pulses.

In FIG. 8, the annular structure contains neon and copper vapor as one typical example. As is known in the art, a discharge tube 10 as shown in FIG.
When an electric field is applied to, the electric field penetrates from the outside toward the center in the radial direction, and a laser beam pulse is generated. But,
As mentioned above, two factors occur that limit the generation of higher magnitude pulses that can be used in copper vapor lasers.

One factor is the gas heating effect. Due to the gas heating effect, 1500 ° C outside the discharge tube shown in Fig. 8.
To 3000 ° C. at the center of the discharge tube. It is conventionally known that excessive heating of the center of the discharge tube thermally creates a stable, low laser level, which considerably limits the usable discharge tube diameter.

Another factor affecting the ability to increase output levels in conventional devices is the radial dynamic effect described above. In conventional devices,
Since the electric field does not uniformly penetrate from the outside of the discharge tube toward the center, the “chevron effect” is generated in the generated laser beam. This is shown in FIG. For clarity, one pulse is shown, but this pulse accurately represents the intensity of the laser beam over time. The X-axis shows time in nanoseconds (ns) and the Y-axis shows radius in centimeters (cm). As you can see from Figure 9,
A series of laser beam pulses 12 is caused by the chevron effect, leading edge 14 and trailing edge 16
In, it has a non-uniform cross-sectional area. This has a major impact on the overall operation of all systems that require uniform high power pulses. The effect is particularly large on the leading edge and the trailing edge.

The present invention addresses the aforementioned gas heating and radial dynamics problems,
It aims to improve the problem of gas heating and to minimize the chevron effect. Thus, according to the present invention, high output can be achieved.

FIG. 1 shows a sectional view of the improved laser beam generator of the present invention. In FIG. 1, an improved laser beam generator 20 includes a partition 22 inside a discharge tube.
have. The partition wall 22 is held by a part of the inner wall 24 of the discharge tube 20. The septum according to the invention is shown in more detail in FIG. FIG. 2 is a vertical cross-sectional view of the CVL discharge tube 20, showing a plurality of barrier ribs (22
-1, 22-2, ... 22-N) is clearly shown.

The CVL discharge tube shown in FIG. 2 has a length of 2 m, and each partition 22 has a height of 0.06 m and a width of 0.1 m. And the distance between each partition 22 is 0.05 m.
Is. However, the size of the partition wall is not limited to these, and other values can be used.

The overall advantages the present invention has over the prior art are illustrated in greater detail in FIGS. 3, 4 and 5. FIG. 3 shows an improved discharge vessel 20 having barrier rib means 22.
Figure 3 shows a cross-section of the device, showing heat dissipation in the device of the invention. FIG. 4 shows a cross section of an improved device with a partition, showing the electric field created therein. FIG. 5 is a graph showing the generation of a series of laser beam pulses 30 according to the apparatus of the present invention. As can be seen from this graph, the chevron effect is minimized or eliminated.

Referring to FIG. 3, it can be seen that, according to the present invention using a partition, the heat dissipation is diffuse due to the partition 22 located in place inside the annular structure 20.
This is in contrast to the heating problem in the prior art shown in FIG. Clearly, the heat dissipation in the device of the invention solves the problem of overheating in the middle of the discharge vessel. In addition, the usable discharge tube diameter is not limited as in the conventional device described above.

FIG. 4 illustrates the formation of an electric field in the device of the present invention. The electric field penetrates along the outside of the discharge vessel and also along the barrier ribs. Obviously, the radial penetration of the electric field as shown in FIG. 4 produces a laser beam pulse which is clearly different from that of the prior art device.

Although the chevron effect as shown in FIG. 9 in the conventional device is caused by radial dynamics, the device of the present invention produces a laser beam pulse as shown in FIG. As is clear from FIG. 5, the chevron effect is minimized. X in FIG.
The axis and Y-axis scales are the same as in Figure 9, with the X-axis indicating time in ns
In units, the Y axis shows the radius in cm. The chevron effect is minimized. It is made possible by the partition means arranged inside the discharge tube as shown in FIGS.
This is because the electric field applied in the discharge tube can penetrate in the radial direction. However, it should be noted that the radial penetrations are different, as opposed to attempting towards the center of the discharge tube as previously attempted. This is because an electric field is formed on the barrier rib means in the same manner as an electric field is formed outside the discharge tube. As a result, the radial penetration of the electric field is from the outside of the discharge vessel 20 at 32 and 34 in FIG.
You will head to the position indicated by.

According to another aspect of the present invention, slide-in capability is provided. The slide-in capability is the ability to slide and insert one or more partition walls into the laser discharge tube.

FIG. 6 shows a cross section of a laser discharge tube provided with slide-in capability according to the present invention.

FIG. 6 shows a laser discharge tube having inner grooves formed in a straight line and separated from each other by approximately 180 degrees. The dimensions of the laser discharge tube shown in FIG.
3.375 inches (Example A) and 3.060 inches (Example B).

FIG. 6B is a sectional view of the improved laser beam generator of the present invention, in which the central portion (left side) and the end portion (right side) are connected to each other. As aforementioned,
The present invention provides slide-in capability that allows the septum to be slidably inserted into the laser discharge tube as will now be described.

7 (A) and 7 (B), the cross section of the partition wall is shown in a size corresponding to the size of FIG. 6 (A) (Example A) and FIG. 6 (B) (Example B). Has been done. The barrier rib shown in FIG. 7 is inserted into the laser discharge tube shown in FIG. The internal groove shown in FIG. 6 extends the entire length of the central portion of FIG. 6B and extends within 0.500 inches to the threaded portion formed at each end of FIG. 6B. .

The central portion has an internal thread portion, and the end portion has an external thread portion. The barrier rib must be slid into the discharge tube assembly shown in FIG. Also,
The grooves must be formed 180 degrees apart and aligned when the tubes are assembled.

The material used is preferably 99.5% pure aluminum oxide (Al ₂ O ₃ ) with minimal impurities.

It has been found that by providing the laser pulse generator with a partition wall accommodation property, the problem of radial dynamics is substantially solved, and thereby a discharge circuit having a large diameter can be realized. In addition to this, the provision of the partition reduces or overcomes problems with heating.

Further, in the general operation of the high-power laser beam device, the above-mentioned problems relating to the discharge tube are overcome, and no new problem occurs in terms of proper operation.

Therefore, the present invention brings about a remarkable improvement over the prior art in increasing the output of the copper vapor laser.

The above description of the preferred embodiment of the present invention is as follows:
It is for explanation and illustration. The present invention is not limited to the embodiments disclosed herein, and many improvements and modifications can be made within the scope obvious from the above disclosure. The embodiments described above have been chosen to best explain the principles of the invention and its practical application, so that others skilled in the art may use the invention and its various embodiments for particular uses. In a suitable form,
It can be used well. The scope of the invention is defined by the claims.

[0041]

According to the laser beam generator of the present invention,
Problems such as radial dynamics and the chevron effect that cannot be avoided by conventional devices can be overcome.

[Brief description of drawings]

1 is a cross-sectional view of an improved laser beam generator of the present invention.

FIG. 2 is a vertical sectional view of an improved laser beam generator according to the present invention.

FIG. 3 is a cross-sectional view showing heat dissipation in the device of the present invention.

FIG. 4 is a cross-sectional view showing electric field formation in the device of the present invention.

FIG. 5 is a graph showing one occurrence of a laser beam pulse that minimizes or eliminates the chevron effect.

FIG. 6 is a cross-sectional view of an improved laser beam generator having slide-in capability.

FIG. 7 is a cross-sectional view of an improved laser beam generator having slide-in capability.

FIG. 8 is a sectional view of a conventional laser beam generator.

FIG. 9 is a graph showing a laser beam pulse having a chevron effect.

[Explanation of symbols]

 20 discharge tube 22 partition wall

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication location 7454-4M H01S 3/097 B (72) Inventor David B Duncan USA, 95603 California, Pillite, California Lane 2050

Claims (8)

[Claims] 1. An apparatus for generating a series of laser beam pulses, comprising a substantially annular laser structure for generating a series of laser pulses, the laser structure traversing the structure itself. It has means for generating the series of laser beam pulses by intermittently applying an electric field, and further has partition wall means for dissipating heat generated at a predetermined position inside the annular structure, wherein the partition wall An apparatus wherein each segment of the means comprises means for providing slidability such that the septum means itself can be slidably inserted within the annular structure. 2. An apparatus for generating a series of laser beam pulses, comprising a substantially annular laser structure for generating a series of laser pulses, the laser structure traversing the structure itself. Separating means for generating a series of laser beam pulses by intermittently applying an electric field and for generating laser pulses having a relatively uniform intensity pattern from the outside to the inside over time in cooperation with itself. Further, which causes each pulse to have a substantially uniform cross-section over its entire length, including leading and trailing edges, to minimize the chevron effect and each segment of the septum means An apparatus comprising means for providing slidability for allowing the septum means itself to be slidably inserted within the annular structure. 3. An apparatus for generating a series of laser beam pulses, comprising a substantially annular laser structure for generating a series of laser pulses, the laser structure traversing the structure itself. It has means for intermittently applying an electric field to generate the series of laser beam pulses, and further has partition means, wherein the partition means is one or more or more longitudinally arranged in the laser structure. Of the partition means, each segment of the partition means having means for providing slidability for allowing the partition means itself to be slidably inserted within the annular structure. 4. An apparatus for generating a series of laser beam pulses, comprising a substantially annular laser structure for generating a series of laser pulses and an intensity pattern in a cross section of each pulse including a leading edge and a trailing edge. And means for removing the chevron effect as being substantially uniform over its entire length, wherein the laser structure intermittently applies an electric field across the structure itself to generate the series of laser beam pulses. And a partition means for dissipating heat generated at a predetermined position inside the annular structure, the partition means being 1 or 2 longitudinally arranged in the laser structure. Sliding insertion consisting of the above partition wall segments, and each segment of the partition wall means allowing the partition wall means itself to be slidably inserted into the annular structure. Comprising a means for providing a superficial device. 5. A laser device comprising an annular structure extending in the longitudinal direction and means for operating in the annular structure to generate a series of laser beam pulses, the laser device being generated at a predetermined position inside the annular structure. The partition means for dissipating heat, and each segment of the partition means has means for providing slidability for allowing the partition means itself to be slidably inserted into the annular structure. apparatus. 6. A laser device comprising a longitudinally extending annular structure and means for operating within said annular structure to generate a series of laser beam pulses, each pulse cooperating with said annular structure. Has a cross section substantially uniform over its entire length including the leading edge and the trailing edge, thereby removing the chevron effect, each segment of the partition means having the partition means itself in the annular structure. A device comprising means for providing slidability for slidable insertion within a body. 7. A laser device comprising a longitudinally extending annular structure and means for operating within the annular structure to generate a series of laser beam pulses, the laser device being longitudinally disposed within the laser structure. 1 or 2
It has a partition means comprising the above partition segments, and each segment of the partition means has means for providing slidability for allowing the partition means itself to be slidably inserted into the annular structure. Device. 8. A laser device comprising a longitudinally extending annular structure and means for operating within said annular structure to generate a series of laser beam pulses, each pulse cooperating with said annular structure. Comprises a partition means for substantially uniforming its cross-section over its entire length, including leading and trailing edges, thereby eliminating the chevron effect, and means for dissipating heat generated in place within the annular structure. The partition means includes one or more partition segments longitudinally arranged in the laser structure, and each segment of the partition means allows the partition means itself to be slidably inserted into the annular structure. A device comprising means for providing slidable insertability.