JPH01502562A - Precision laser system useful for eye surgery - 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] ・　　　　　　　　　　　　　　　　--Sysumu Husband sumi! 2jLJL The invention is particularly suitable for laser systems, more particularly for medical and industrial applications. related to laser systems.

− In the shell, the laser acts on the target by destroying part of the target. Ru. Lasers are used to target targets with the wavelengths generated by the laser. selected to absorb a sufficient amount of energy to

Examples of laser uses include medical use. For example, lasers can be used to treat abnormalities on the eyelids. It can be used to dissect tissue, such as to remove objects and polyps. this purpose The commonly used laser is a carbon dioxide laser that operates at a wavelength of 10.6 pm. Yes, water molecules absorb well at this wavelength. Since water is a basic component of animal tissue , the laser light is absorbed by tissue.

Other uses include ophthalmic surgery, such as making an incision in the iris. many In ophthalmological applications, it penetrates the cornea, is substantially not absorbed by the cornea, and is preferentially absorbed by the iris. It is necessary to select a wavelength that will be absorbed first.

Many existing laser systems are suitable for medical and other applications, but they are not without drawbacks. For example, different lasers may be used for individual applications depending on the absorption characteristics of the target. A user system is required. In other words, in a hospital operating room, there are two It is necessary to prepare more than one laser.

Another problem with many existing laser systems is the risk of damaging surrounding tissue. The point is that This may be due to the fact that biological tissue is a broadband absorber.

Tissues surrounding the target area, such as the cornea in front of the iris, are part of the incident laser radiation. and cause unwanted damage to the cornea.

Additionally, the spot size of the bundled laser pulses becomes very large, making it undesirable to Performs precise processing without causing damage, especially thermal damage to the surrounding tissue of the target area. It is difficult to implement.

Another problem with many existing laser delivery systems is that the incision width is fixed. 0 cases where the incision depth was larger than necessary due to the incision being unable to be adjusted. For example, current corneal refractive surgery involves creating an external surgical wound up to a predetermined level in the stroma. The depth of such wounds is difficult to control and often In addition, combining such wounds can result in high refractive errors or The desired effect of changing the corneal curvature may not be achieved due to astigmatism. It's been found. Precise control over the size and location of the laser incision For example, in corneal surgery, each incision must be It has targeted and anatomical effects. Corner by making fewer incisions and modifying the amount of thickness Attempts to precisely correct membrane curvature have had some clinical success, but no gains have been made. The accuracy of the correction provided is still highly variable, especially in otherwise normal eyes. Not available for routine clinical use.

Additionally, corneal incisions for cataracts and corneal transplants can induce excessive astigmatism, leading to secondary surgical correction is often required.

Furthermore, traditional corneal surgical incisions or refractive corrections induce continuous and irregular refractive changes. corneal incisions or more that have to compromise Bowman's membrane with the result that Bowman's membrane can be kept intact during ablation of deep cortical structures corneal curvature is more easily quantifiable and better maintained by surgical intervention. Or it could be modified.

Perform precision incisions using ultrashort pulses to minimize thermal and non-thermal damage. Attempts are being made to develop laser systems for this purpose. f! ultrashort pulse bundles in a small area, thus limiting damage to a very small area within the target be able to. However, ultrashort wave pulses that spread over a narrow area are extremely difficult to use. Performs incisions and other cuts at a speed fast enough to perform for any medical and industrial purpose For example, if the pulse duration is 10 ps, If the elapsed time between pulses is 50 ps, then the target used is The system can move the focal point of the laser within 50 picoseconds. 20000 m/s (10 series) if the damage zone is 101I-. -750 picoseconds), which requires repositioning the target zone at a speed of is impossible to realize. Therefore, very small Combining a deep damage zone with ultrashort pulses is extremely difficult.

Another problem with ultrashort pulse systems is the lack of consistent energy levels between pulses. The problem is that it is difficult to achieve the desired value, ie, output failure occurs. child It consists of a laser used to generate ultrashort pulses and a target used to amplify ultrashort pulses to energy levels high enough to This may be due to insufficient synchronization with the laser being used. When jitter occurs , the target cannot be processed consistently, and some areas are processed but , another area of the target will be severely damaged.

Another problem with existing laser systems is that they are difficult to align and mechanical The problem is that it is complex and has a high frequency of failure.

To overcome these problems with existing systems, accurate cutting at useful speeds is required. Ultra high frequency waves that allow you to control the target zone dimensions to perform cutting A laser system that provides pulses and a small target zone is needed.

Furthermore, it is mechanically simple and can be easily aligned with the laser and target. Effectively used on biological tissue without damaging surrounding tissue such as tissue between zones A system that can do this is needed.

1 to 11 The present invention provides a laser system that satisfies these requirements. The system is Means for generating laser radiation pulses and shortening the duration of the main pulse ° pulse shortening system or zone, preferably to increase the number of pulses pulse multiplication system or zone and the target is absorbing to the output beam wavelength. Sufficient radiation to form a plasma, whether absorbing or non-absorbing A sufficiently small spot size in the target to get the illumination intensity into the target. and a beam delivery system including bundle means for bundle the force pulses. Ta The irradiance obtained during the target is at least 1013 watts/c-2; 10'! )/cm' or more is also possible.

The main laser radiation pulse is connected to the excimer laser that generates the input pulse and each input pulse. generated by a beam splitter that splits the pulse into a pump pulse and a main pulse. can be born.

The pump pulse is pumped into the amplifier laser by a shortening system and a pulse multiplication system. used for sampling.

5! ! In a compact system, the duration of each main pulse is arranged in a cascade. It is shortened with a series of shortener/amplifier stages.

Each stage includes at least one pulse shortener that shortens the duration of each main pulse; at least one pulse amplifier for amplifying the main pulse. first pal The shortener is excited by each main pulse. Each pulse generated from the first pulse shortener The straightening pulse is amplified in a first stage pulse amplifier. Radiation generated from each stage is sent to the next successive stage pulse shortener, and the pulses generated from each stage pulse shortener are The signal is amplified by the current stage's pulse amplifier before being sent to the next stage. This system The system is useful for shortening the pulse duration, and the generated pulse is For example, if the duration of the main pulse is less than about 17,100 times the duration of the pulse is less than For longer than 1 nanosecond, the duration of the pulse generated by the shortening system is 100 pm. It may be less than 10 picoseconds, preferably less than 10 picoseconds, and may even be on the order of about 1 picosecond.

Preferred pulse shorteners of the invention absorb energy from an incident radiation pulse. dye solution with a front or entrance window and a rear or exit window and means for containing the solution. The two windows have interior surfaces. front It is possible to transmit at least a portion of the incident pulse into the dye solution. Before In front of the front window, the radiation pulse entering the dye solution through the front window is focused between the windows. The light is optically bundled to generate radiation in the dye solution by amplified spontaneous emission. Educational means are arranged. The two windows are substantially transparent to the generated radiation. Yes, the front window reflects a portion of the incident radiation generated to the focal point. The focus is on the front window. Because of the close proximity, the emitted and reflected radiation becomes active before the laser emission begins. Re-entering the sexual focus area. As a result, all stimulated emission occurring in the focal region disappears, Laser emission is avoided, thus amplifying and shortening the output pulse generated. The radiation passes through the rear window as an output pulse, and the generated radiation is transmitted from the rear window to the focal point. Qualitatively not reflected at all, the focal point is the shorter duration of each incident laser radiation pulse. positioned between the front and rear windows to have a single respective output pulse between It will be done.

The advantage of this system is that it is easy to use. The duration of the output pulse depends on the dye dissolution. adjusting the optical means to change the position of the focal point in the liquid with respect to the first window; and can be controlled by. The duration of each output pulse is the duration of the respective input pulse. and preferably less than about 1710.

Typically the front and rear windows are spaced at least III The distance between the inner surfaces of the front window is preferably greater than that of the rear window. at least 30% of the d distance between the surfaces. The generated radiation reflected by the rear window is To prevent reaching the point, place the rear window at an angle of e.g. By doing so, the output pulse is tilted at a predetermined angle.

The main advantage of the pulse shortener of the present invention is that the amount of amplification obtained in the amplification stage is realizable between pulses. It is said that it can operate qualitatively without becoming cloudy, that is, without jitter. At the point. Because the shortener operates on the principle of amplified spontaneous emission rather than stimulated emission, , a single beam splitter that uses a beam splitter to supply the pump pulse to the amplifier. It is possible to operate the shortener/amplifier stage with one excimer laser. same One laser provides pump and input pulses to the shortener/amplifier stage Therefore, in order to obtain consistent amplification at each amplifier stage, the pump pulse and input pulse are No more synchronizing problems. This allows for consistent amplification from pulse to pulse. This allows for consistent and reproducible processing on the target.

As shown above, ultrashort pulses, especially ultrashort pulses that bundle in a small area. The practical problem with this is that it is difficult and time consuming to make large cuts. It's in °. very! ! Target pulse without losing the advantage of having a short wave pulse To increase the number of pulses, use a pulse multiplication zone or system. Multiply the number. At least one pulse multiplier is arranged in the pulse multiplier zone. , each pulse entering the pulse multiplier generates multiple pulses spaced apart in time. Ru. Preferably, the pulses generated by the pulse multiplier are also spatially spaced apart from each other. There is. The expression "spatially separated" means that the pulses are focused by a suitable lens. When focused, it means that the focused pulses are spatially separated.

The pulse multiplier of the present invention consists of a closed cell with a front window and a rear window, The two windows have inner surfaces and substantially the same index of refraction. In the cell, the refractive index of the window a medium that has a substantially equal index of refraction and is substantially transparent to incident laser radiation; The quality is well placed. The cell further includes mutually opposed front and rear parts in contact with the medium. at least one of the reflecting means is such that the output pulse is spatially Curved to separate. Preferably, the front and rear reflective means are respectively and the inner surface of the rear window, the zero reflective means includes a It has a reflectance of at least about 80%.

The expression “substantially transparent” media or windows means that the media or window has a This means that at least 90% of the light is transmitted.

With this pulse multiplier, a portion of each incoming laser radiation pulse passes through the front window. The light then enters the cell and is reflected back and forth between the reflecting means. Get to the rear reflective means A portion of each pulse is one of a series of temporally spaced output laser radiation pulses. Since at least one of the rear window and the transmitting zero reflection means is curved, the output pulse are spatially separated from each other. The mutual distance of the windows is determined by the time required for sequential pulse viewing. Depending on the spacing, it can be from about 1 to about 100 m5, preferably from about 5 to about 20 m5. .

According to the preferred embodiment of the present invention, the amount by which the output pulses are spatially separated from each other is varied. The means for changing the curvature of the reflecting means to mutually spatially change Ji H will be placed.

This is done by containing a fluid medium in a cell and varying the pressure of the fluid with controlled means. The zero curvature that can be realized by They can be controlled to be spatially separated by a maximum of 1011 m or more.

The continuous pulses generated from the pulse multiplier cause the laser radiation to reach the front and rear reflectors. Depending on how many times it is reflected back and forth, it has a smaller beak power. Ta To effectively affect the target, all pulses reaching the target must be nearly identical. It is important to have a peak power of This amplifies the spaced pulses. Amplify the output pulse from the multiplier with at least one pulse amplifier to This is accomplished by generating power output pulses and low power output pulses. low The power output pulse has a substantially lower peak power than the high power output pulse generally less than about 1710 of the peak power of the high power output pulse, more preferably or less than about 17,100 of the peak power of the high power output pulse. That is, low The power output pulse is of insignificant magnitude. For each pulse input to the pulse multiplier preferably at least two high power output pulses with approximately identical peak powers. Or at least 5 exist. Multiple pulse multipliers can be used to further multiply the pulses. Multipliers may be used in series.

Preferably, the system of the invention uses pumping pulses generated in the generation zone. Pump all amplifiers in the stem. In the amplifier following the pulse multiplier, the main spatially spaced pulses by delaying the pulses from reaching the amplifier. It is possible to selectively amplify some of the pulses over other pulses. In this way, Bon The time for the ping pulse to reach the amplifier and the time for the spatially spaced pulses to leave the multiplier By controlling the arrival time and timing of each human pulse of the pulse multiplier, The number of high power output pulses generated at the time can be controlled.

This system uses near-gauge, which is important for obtaining small spot sizes during targeting. provides an output pulse having a transverse spatial profile. small spot size The beam delivery system for obtaining and a pair of lenses for stretching and collimating the output pulses. There is. The elongated and collimated output pulse passes through the z-east objective and the ko-to objective. Means are provided for controlling the focal plane of the lens. The focusing system is 30-4 By using a wide cone angle of 0°, spots smaller than 10μ, e.g. Pulsed straw can be bundled to different sizes.

The laser system of the invention may include an imaging system, The imaging signal is focused on the target, and as a result of the imaging signal, the target The signal generated from the aS travels along the imaging path and is collected by the aS. and displayed on a display means such as a video screen. laser radiation pulse The focal plane of the straw bundle objective is the same as the focal plane of the imaging system and the straw bundle objective. The focal plane of the lens is controlled so that it is the same as the focal plane of the lens. 8 Preferably, the image of being bundled with straw. The pulse signals and bundled laser radiation pulses are aligned in the same line for ease of operation. placed on top. After the laser pulse from the target to the imaging system Directional scattering involves polarizing the laser beam with a first polarizer and with respect to the first polarizer. This can be avoided by placing a second polarizer in the imaging path, rotated by 90°. It will be done.

This laser system has many substantial advantages.

For example, an ultrashort pulse of less than 100 ps, preferably less than 10 ps in -a is formed. These short pulses cause damage to the tissue surrounding the target area tlt Become smaller.

Furthermore, precise small cuts can be made. Near gau of laser radiation pulse Due to the spot size distribution and wide cone angle of the straw bundle system, spot sizes of less than approximately 101 J- law can be achieved.

Wide cutting by controlling the interval between pulses generated by the pulse multiplier can also be implemented. Controllable cutting with a width of about 10-11001I It is possible. Pulse multiplier allows cuts of the same width and length as those of the prior art3 Can be carried out at very shallow depths, smaller than those obtained with prior art systems .

The combination of extremely small spot size and ultrashort pulses enables Plasma can be reliably formed on the target. Plasma depends on the target Formed without the need for absorption. This makes the target transparent to laser radiation. The present invention provides that the transferred energy is absorbed by a selective absorption mechanism. Since it is system independent, it is possible to create precise and localized damage zones. So On the contrary, the laser beam does not move beyond the plasma into a strictly defined plasma formation region. Does not conduct virtually any outside energy.

Since the energy transfer mechanism does not rely on absorption, the operating wavelength can be directed to the target region. conduction and may be selected to maximize. This provides a high level of safety in non-target areas. Wholeness is obtained.

Additionally, a single laser system can be used for multiple specimens and Change the wavelength of the output radiation or modify the laser system to match the absorption characteristics of the target. Therefore, all you need is one laser system in the operating room. There is no need to have multiple systems.

Another advantage of systems embodying features of the invention is that they are shielded from laser deception sources. target, e.g. the iris, which is occluded by the cornea; The 0 cone angle is wide, allowing surgery to be performed without causing any harm, making it extremely small. The shielding tissue in front of the target can form a focus with a large spot size. is not damaged.

Another advantage of the system of the invention is that the frequent pulses obtained from a single pulse multiplier are It can be on the order of 10 to 300 times/second, 1.0 when using two or more multipliers. 00,000,000 pulses/second, allowing for efficient and quick operation. The point is that

The main elements of the system of the present invention are a pulse shortener and a pulse multiplier. It is an output device, in other words, the pulse enters from the front window and exits from the rear window, so Mechanically reliable and easy to align.

According to Mr. 1, the pulse amplifier used is a dye laser. Therefore: By simply adjusting or changing the dyes used, it is possible to obtain rays at virtually any radiation wavelength. stem can be used.

Additionally, it is used in pulse shorteners to simply control the amount by which the incident pulse is shortened. By changing the position of the straw bundle means, the system can be operated with variable input pulse duration. The above and other features, aspects and advantages of the present invention will be described in the following detailed description and claims. A better understanding of the scope of the request may be obtained by considering the scope of the application and the accompanying drawings.

Note that FIG. 1 is a front view of a laser surgery device according to one embodiment of the present invention, and FIG. A flow sheet showing part of the laser system of the device shown in the figure. Schematic diagram of the shortening device used in the laser system, Figure 4 shows the laser system in Figure 2. Another pulse shortening device used in the system is approximately 1121 sections, and Figure 5 shows the system in Figure 2. Figure 6 is a partial cross-sectional side view of a pulse multiplier that can be used in a device in Section 1. This is the approximate Q section of the beam emission system and monitoring system used.

Note J box 1 ink- 1.21 m No. 17 depicts a device of the present invention useful in ocular surgical procedures.

The device has a target that is absorbing or non-absorbing to the laser radiation pulse. Straw bundles in a small area to generate plasma in the target regardless of whether 8i ultrashort wave high power laser radiation power to treat targets with high firing speed It is possible to do so. The system can generate 1 to 30 bursts per second. each burst is at least 10 pulses (at least 10-300 pulses) per second), each pulse forms a damage zone with a diameter of 6 to 10011 m, and each The distance between the focal points of the pulses within a burst is controllable between 0 and 10011 m.

The pulses reduce the irradiance achieved in the damage zone to most materials and virtually all living organisms. at least 1013 watts/cm, which is sufficient to form a plasma in the material It has enough power to become 2.

In the first section, a device 10 suitable for laser eye surgery supports a patient on a support pad 16. A frame structure 12 is provided which provides a top surface 14 for the purpose of the present invention. ! ! , Person 18 The patient's head is held firmly by the head restraint means 2o while lying on the support pad 16. and fix it.

The frame assembly includes a base 22 that includes an input laser system. When the system 24 is supported, the input laser system 24 is connected to an aperture outside the operating stage. It is housed separately in Pace. Above the input laser system 24 and below the patient A laser pulse processing system 26 is located at.

The bottom of the frame structure 12 includes a plurality of leveling mounts to level the device. 27 is attached.

Above the patient's head is a beam emitting system 28 and an imaging system 30. The imaging system includes a viewing monitor 32 . emission The stem 28 and imaging system 30 are mounted on a rigid, anti-vibration main gantry frame. The frame 33 is positioned over the head of the patient 18 and It is attached to the main frame structure 12 at its head. The viewing monitor 32 is a gantry - supported by an arm 34 extending from a frame 33; beam emission system system 28 is controlled by controller system 36. controller system 36 is located at the head of the frame 12 adjacent to the input laser generation system 24. Ru. A shoulder of frame structure 12 includes a unit for processing system 26, such as a vacuum pump 40. utilities are located to circulate and circulate the gases used by the input laser system 24. and purge.

A plurality of laser radiation pulses 44 are generated by input laser system 24 .

These pulses are divided into a pumping pulse and a main pulse. Processing system 2 6, each main pulse is shortened and then multiplied and spaced apart in space and time. Generate multiple pulses. The spaced apart pulses are then amplified in processing system 26; to the beam delivery system 28 to bundle the straw onto a selected target in the eye of the patient 18; Sent. Imaging system 30 determines where on the target the beam is emitted. Showing the operator how the system 28 is transmitting laser radiation pulses is possible. A control system 36 controls the location of the damage zone in the target. In FIGS. 1 and 2, the generation system 24 has a plurality of input pulses 44. It includes an input laser 42 that generates. Preferably, the generating laser 42 has a lifetime. long-lived, reliable, and sufficient to generate plasma in the target area. Power XeCI excimer laser. A suitable excimer laser is about 4 It generates pulses of 0 to 2000 sj, and the pulses have a duration of about 5 to about 8 nanoseconds. It has a period of approximately 30 hertz.

Each human power pulse 44 sent substantially horizontally by an input laser 42 is transmitted to a first reflector 4. 6 and then horizontally by the second reflector 48. It is converted and used in the processing system 26 on top of the frame structure 12. after that, The pulses are split by a first beam splitter 50, with approximately 90% of each pulse being Bumping parameters for pumping dye laser amplifiers as described below. The remaining 10% of the pulse is passed through the third reflector 54. It is re-reflected as the main pulse 56 and further processed. The first reflector 46, the second Each of reflector 48 and third reflector 54 is an aluminum mirror or a right angle prism. It can be. The first reflector 46 and the second reflector 48 are compact to the device 10. It functions to give shape.

A major advantage of the system of the present invention is that it can be used to pump dye cell amplifiers. is processed to generate a bombing pulse 52 and a plurality of [F ultrashort pulses. Using a single excimer laser 42 to provide the main pulse The point is that it can be done. Processing targets in this way using a single input laser The jitter in the output pulses used to do so is reduced.

In Figure 2, the double arrows next to each element of the system are for R1 of the system. , and control the parameters of the output pulse including duration, frequency and energy. The arrow symbols indicating the degrees of freedom of movement available to each element for control have the following meanings: do.

〈〉〉　One-dimensional translation in the horizontal direction.

〈:〉 Two-dimensional translation in the horizontal and i9 orthogonal directions.

〈:〉　Three-dimensional translation.

The processing system modifies the main pulse to obtain an output pulse with the following characteristics:

(1) Near-Gaussian transverse profile; (2) short enough to avoid damaging tissue surrounding the target area Pulse duration, generally less than about 100 ps, preferably less than about 10 ps, maximum Suitably less than about 1 picosecond: (3) a pulse frequency high enough to generate a dense plasma in the target area; wave number; and (4) Enough energy in the pulse to break most chemical bonds in the target area. Rugie.

Pulse processing systems include pulse shortening systems, pulse multiplication systems, and pulse amplification systems. Contains the system.

B, pulse, system The pulse shortening system includes multiple shortening/amplifier stages 56. Shown in Figure 2 According to Ba of the present invention, three stages 56A, 56B and 56C are arranged in series. ing. Each stage 56 includes a shortener assembly 58 and an amplifier assembly 602. Ru. Regarding shortener/amplifier stages, similar elements in different assemblies have the same reference numbers The first, second, and third stages are distinguished by subscripts ^, B, and C, respectively. Each stage 56 is shall have a single shortener assembly 58 and a single amplifier assembly 60. However, in some cases one or more stages may include two or more amplifiers and/or two or more amplifiers. The shortener may be used to reduce the pulse duration. It also reduces the energy of the pulse, so an amplifier is required. Ten human pulses If the shortener assembly is sufficiently efficient, In some cases, an amplifier may be placed after the shortener assembly! You don't have to, Pal. A shortening system generally includes at least one shortener and at least one amplifier. include.

Each shortener assembly 58 has a straw bundle lens 62 and a pulse shortener 64. 1st In front of the straw bundle lens 62^, there is a A neutral density filter 66 is arranged to reduce the intensity of the input pulse 56. There is.

The first shortener assembly 58 further blocks divergent light, such as due to fluorescence. iris diaphragm 68 is included after the pulse shortener 64A to further space-wave the pulse shortener 64A. I'm here.

In the third section, each pulse shortener 64 has a dye cell having a front window 72 and a rear window 74. 0 and the two windows can be made from quartz glass. Inside this cell is Contains a dye solution flow. tE or self 0 is a continuous flow cell . A straw lens 62 bundles the incident pulse through the front window 72 of the cell into the dye solution. The dye solution is excited at a focal point 77 between the front window 72 and the rear window 74, and the amplified Spontaneous emission generates radiation within the dye solution. Front window is incident laser radiation pulse permeates into the dye solution. Two windows are used for the generated radiation. Being substantially transmissive, the front window 72 directs at least a portion of the incident generated radiation to a focal point 77. reflect. The front window 72 reflects the generated natural radiation to a focal point 77. , acts to extinguish the stimulated emission, so no laser ° is emitted, and the shortener 6 4, only one short pulse is emitted for each incident pulse. Preferably, The front window transmits at least 90% of the incident radiation pulse into the dye solution, and the rear window transmits at least 90% of the incident radiation pulse into the dye solution. The generated laser radiation that reflects less than approximately 10% of the generated laser radiation incident on the window is The generated radiation passes through the rear window 74 as an output pulse, and the generated radiation is transmitted substantially from the rear window to the focal point. It is not reflected at all.

The front window has a reflectance of approximately 4% that can be obtained naturally with most quartz glass. Therefore, sufficient extinction is obtained by reflection off the inner surface 78 of the front window 72. front The output pulse is shortened and The excitation distribution remaining in the active region for amplification is reduced.

The location of the focal point 77 relative to the front window 72 and rear window 74 is important to the operation of the shortener 64. It is. If the focal point 77 is very close to the front window 72, each manual pulse More than one output pulse can be generated. Furthermore, the focal point 77 is either the front or rear window. moves closer to one side, so that during the duration of the output pulse, the interleaving with the open surface 78 The distance Wd is the leap distance M between the inner surface 78 of the front window 72 and the inner surface 80 of the exit window 74. It is less than about half of L. In other words, the lens 62 generally has a focal point 77 at the rear. It is formed so as to be closer to the front window 72 than the front window 74 and is adjustable. be done. In order to obtain a single output pulse of short duration, preferably the distance d is at least about 30% of L. The front and rear windows generally have a diameter of at least about 1 mm. Although they are arranged at intervals, they may be arranged at intervals on a 20-ring ring.

The front and rear windows may be flat as shown in section 3.

However, as in the embodiment of the present invention shown in FIG. 4, the front window 81 may have a different shape. It may be flat or convex, or it may be concave and convex as shown in Figure 4, with the convex surface being the inner surface 8. According to the '89 version of the present invention shown in FIG. 4, the front window may be When there is incident light and reflected light, the reflected light is focused on a focal point 77.

The curvature of the inner surface 82 of the front window 81 shown in FIG. is selected such that all generated radiation is reflected to the focal point 77 and focused to disappear. .

Similarly, as shown in FIG. The optical axis may be arranged at an angle with respect to the optical axis so that the optical axis can be Preferably the rear window is It is tilted by Brewster's angle to avoid reflection loss.

The focusing lens 62 may be any lens that focuses the incident pulse into the dye solution. For example, the first and second shortener assemblies 58A and 58 In B, straw bundle lenses 62^ and 62B may be plano-convex. On the other hand, as shown in Fig. Similarly, the focusing lens 62C of the third shortener assembly 58C may be biconvex.

The amount of shortening obtained by the pulse shortener 64 depends on the position of the focal point 77 relative to the front and rear windows. By moving the focusing lens 62 laterally so as to change the Can be done. The output pulse has a duration less than about 172 times the duration of the input pulse. The duration of the output radiation pulse is typically the duration of the input pulse. It may be less than about 1710 hours.

The dye used in each pulse shortener 64 absorbs in the focal region at the wavelength of the incident pulse. Optically excited by energy, short pulses are reached when amplified spontaneous emission is reached. Substantially any dye may be used as long as it generates .

The advantage of the pulse shortener of the present invention is that it can be easily aligned, making it ideal for mass production. It is. Additionally, any incident wavelength and Pulse width is also adaptable and therefore can be used with virtually any type of laser be able to.

Pulse shortener 64 typically has an energy efficiency of less than about 10%. Each shortener 6 The output pulse from 4 has a peak power of about 1% of the peak power of the input pulse. Ru. Therefore, preferably one amplifier assembly is provided for each pulse shortener assembly 58. 60 is tied.

Each amplifier assembly 60 directs a portion of the pumping beam 52 to an amplifier dye cell 90. including reflecting means such as a beam splitter 84 and a mirror 86 for directing the beam to the Each amplifier assembly 52 further converts the pulses from the preceding shortener 64 into amplifier dyes. The amplifier dye cell preferably includes a focusing lens 88 for bundling into the cell 90. 90 is inclined at an angle of approximately 10° to the normal to avoid internal reflections. The nine-dye cell amplifier 90 may include approximately 10-1 optical paths, preferably one immediately preceding the shortening. It is a continuous flow cell that contains the same dye used in the device.

The focusing lens 8S of each amplifier assembly 60 may be any suitable lens for straw bundles. A plano-convex lens is preferable. Each focusing lens 88 has a In order to control the amount of amplification that occurs, the position where the pulse bundles within the dye cell is controlled. Can be moved laterally. Generally, an amplification of about 10 to about 100 times is obtained, i.e. each The peak power of the output pulse from amplifier assembly 60 is the peak power of the corresponding input pulse. It is about 10 to about 100 times the arc power.

We have shown a dye cell that is longitudinally pumped into the input wave train, but not laterally pumped. It is also possible to use dye cells that are mixed.

The amplifier assembly 60 of each shortener assembly 58 is configured to block divergent light. It includes an iris diaphragm 92 for realizing spatial r-waves. final amplifier assembly 60 After the iris diaphragm 92C is used to polarize the light introduced into the pulse multiplication system. A ground laser polarizer 93 is arranged.

As will be described later, by combining this polarizer 93 with the second polarizer 229, to avoid backscatter of the laser beam from the target to the imaging system. can be done.

By using cascaded shortener/amplifier stages 60, 1 nanometer An input pulse with a duration of seconds or more is It is possible to modify the output pulse to have a full duration, i.e. the output pulse has a duration of less than 10 picoseconds. The output pulse from the final shortener/amplifier stage 64C may have a duration of about 50 It may have a duration of less than a picosecond.

As many as three, depending on the duration of the input pulse 55 and the desired duration of the output pulse. More or fewer amplifier/amplifier stages 64 may be used in series.

C. Pulse system The main pulse generated from the last pulse shortener/amplifier stage 58C is Each pulse entering assembly 94 emits multiple pulses spaced apart in time and space. is introduced into a pulse multiplier system 94 capable of generating a pulse. pulse multiplier ace Assembly 94 includes pulse multiplier 102 . In FIG. 5, pulse multiplier 102 includes a cell 103 having a front or entrance window 104 and a rear or exit window 106. I'm reading. Two windows 104 and 106 have outward facing surfaces 107 and 108 respectively. are coated with an anti-reflective coating on the inner facing surfaces 109 and 1, respectively. 10 is coated with a highly reflective coating. desired from pulse multiplier Depending on the number of pulses, the reaction is about 80 to about 95%, preferably at least about 85%. An inner coating is used that provides emissivity. The area 152 between the two windows is substantially transparent to the emitted laser radiation and the refractive index of windows fo4 and 106; A medium having a refractive index substantially equal to is disposed.

The important thing is that the medium used does not have a negative effect on the other elements of the pulse multiplier, and that the input that it does not absorb the radiation pulse and that its refractive index substantially matches the refractive index of the window. That is. The two windows have substantially the same index of refraction.

Rather than relying on the inside surface of the window to reflect light, use another reflective surface It is also possible. In other words, it is used to form the outer wall of the cell. The windows do not need to be of identical structure to function to reflect light into the cell. If it is desired that the step be on the inside surface of both the front and rear windows, these windows Can be coated with either aluminum or armor to form a reflector, or is preferred Alternatively, a dielectric coating is used.

A portion of each input laser radiation pulse passes through the front window and enters the cell, causing both front and rear Between the reflective means are preferably reflected back and forth into the darkness of the inner surface of these windows. rear end A portion of each pulse incident on the reflecting means produces a series of temporally spaced outputs. Passes through the rear window as a pulse of laser radiation.

Each output pulse has less energy than the preceding pulse.

At least one of the reflecting means is curved in order to spatially separate the output pulses. let The amount of curvature may be small (for example, each has a radius of curvature of about 1 kilometer) a rear window and a front window having concave inner surfaces spaced apart by approximately 7.51 mm; For cells like this, successive pulses are spaced apart when bundled at a distance of about 10 pm. Ru. One curvature therefore spatially separates the output laser radiation pulses from each other.

The inner surface of the window should be far enough away that the output pulses are independent of each other and do not interfere with each other. , preferably a pulse of the incident beam 11iF) IBM ('full @1dtb, half maximum-). However However, if the windows are located significantly apart from each other, the pulse multiplier system The following amplifier system (used to pump the amplifier in The corresponding pumping pulses that are Force pulses cannot be pumped sufficiently, preferably with an amplification system. The total interval between the first pulse and the last pulse that is amplified to a high power level is , less than half the pulse width (FilIHM).

In order to obtain at least two independent output pulses, the reflection means must be about 1 to about 10 01, preferably spaced apart from each other by a distance of about 5 to about 20 mm.

Preferably, pulse multiplier 102 includes at least one of the reflective surfaces, more preferably Both include means for varying the curvature. This uses a fluid medium in region 152. This is achieved by changing the pressure of the medium using the pressure controller 112. The curvature increases as the pressure increases, thus increasing the spatial distance between the output pulses. distance increases. When a T-flow is applied to the a-quality material, pressure is applied to the reflective surface and the curvature changes. The advantage of piezoelectric materials, which can be solid, such as quartz, is that they prevent leakage of pressurized fluids. It can be used to form a robust multiplier without problems associated with leakage. This is the point.

The multiplier of the present invention can be refined as shown in FIG. Such a multiplier is It has a frame 113. The frame 113 has an inwardly extending support flange 11 4, the flange has a 9M gun window C with inwardly extending ribs 115. +4 is supported around its periphery by flange 114 and by ribs 115 on its front surface. A rubber cushion 116 is arranged between and the rib 115. Front window 104 the edge 120 of the frame 113 between the periphery of the flange 114 and the inwardly facing surface of the flange 114 An O-ring seal 118 is disposed at the 0-ring seal 118. The front window 104 has eight caps. held in place by a front retaining ring 122 fixed to the frame 113 by a screw 124. is maintained. The lateral position of the IIF window 104 is determined by the position of the front retaining ring 122. It can be adjusted with three front adjustment screws 126 equally spaced around the periphery and threaded together. Ru. Each of the adjustment screws 126 is mounted on the front surface 107 of the entrance window 104. Protective block 128 of polymeric material such as rin<(R)> acetal resin be pressed against.

The rear window 106 is mounted in a Delrin® acetal resin holder 130. is attached to the inner surface of the holder 130 and the inner surface 110 of the rear window 106. There is a space between to set the distance between the front and rear windows 104 and 106. A server 130 is arranged. The spacer 134 is attached to the rear window by a plurality of screws 136. It is held in the router 130. Between the rear window holder 130 and the frame 113, An O-ring 138 is disposed between the rear window holder 130 and the periphery of the rear window 106. It is placed. The rear window 106 has a retaining ring 140 screwed onto the frame 113. is held in place within the frame. 3 pieces through the rear window retaining ring 140 equally spaced rear adjustment screws 142 extend and contact the window holder 130. ing. Front adjustment screws 1 to 6 and rear adjustment screw 142 allow adjustment of the front and rear windows. The distance between them can be adjusted.

Additionally, the window can be maintained in the desired orientation relative to the incident pulse by adjusting the adjustment screw. It is possible to hold it.

The frame 113 includes an opening at the front and at the fully opened window 152, and the opening 150 includes a threaded connection 153.

A fluid source (not shown) is supplied through the threaded connection 153 to present a medium to the space. According to a preferred embodiment of the present invention, the pressure of the medium is controlled by the pressure controller 1. more tunably controlled 0 e.g. for gases, floater or bellows type membrane pressure A media regulator may be used. Preferably a controller that maintains constant pressure. 112 is used. The frame can optionally control the pressure of the medium in the space 152. A discharge bleed opening 180 is provided to reduce the force.

A spring-like force that presses outward against both windows to keep them aligned. Biasing means (not shown) may be placed in the region 152 between the mirrors.

This device 102 is capable of changing the focus and the opening interval of successive pulses, having a spacing of 5 degrees less than lpa, i.e. a succession of spacings less than 11116 It is possible to have a focal point of the pulse. The distance between the spaces is the front- and rear-window is controlled by being able to control the curvature of. The pulse multiplier 102 is located at the front and rear. It is possible to adjust the elapsed time between consecutive pulses by changing the distance between the windows It is. This can be achieved by increasing or decreasing the dimensions of the spacer 132. It is desirable to have the pulses generated by the pulse multiplier have different powers. Therefore, it is necessary to process the power of these pulses to balance them. be. This is a method for selectively amplifying spaced apart pulses in a pulse amplifier system. At least one amplifier amplifies the spaced pulses to produce high power output pulses and low power output pulses. This is realized by generating the power output pulse 3. Low power output pulses are high power - has a pulse substantially lower than the output pulse. Has the same beak power There are at least two high power output pulses. Preferably high power output power The ratio of the peak power of the pulse to the peak power of the low power output pulse is at least 1. 0:1, preferably at least 100:1.

The pulse multiplier system includes at least one and preferably a second amplifier. Three amplifier assemblies 60D, 60E and 60F are arranged as shown in the figure. Ru. These amplifier assemblies are used in pulse shortening systems. Substantially the same as BRI 60^, 60B and 60C, beam splitter 84 , Miller 86. Includes straw bundle lens 88, dye cell amplifier 90, and iris diaphragm 92. I'm here. Additionally, the first amplifier assembly 60D of the amplifier system includes a front iris diaphragm. Contains 171.

The final amplifier assembly 60F does not include a beam splitter and has a pumping pulse. mirror to reflect at least 99% of the remaining portion of the signal to the final amplifier 90F. -87.

The purpose of the iris diaphragm 92 is to reduce noise, reduce beam divergence, and reduce near-Gaussian distribution. It is to obtain. The output beam is stretched and collimated, and in some cases can be focused to a small spot size and obtain high irradiance on the target area As such, it is important to have a near-Gaussian distribution.

The time at which the pumping pulse reaches each of the dye cell amplifiers 90 is determined by the main pulse. The pulses generated by the pulse amplifier can be controlled with respect to the time of arrival. An adjustable optical delay assembly provides a 1-hour delay that can selectively amplify signals. 180. This assembly allows one pulse to reach the amplifier assembly. The present invention shown in Section 2 may be placed anywhere within the path of the main pulse before According to aspects of the invention, delay assembly 180 is connected to first pulse shortener assembly 58^. and the first pulse amplifier assembly 60^. optical delay assembly The output beam from delay assembly 180 is collinear with the input beam. Three total reflection prisms 182, 183 and 1 are arranged in sequence so that Contains 84. of approximately 2 nanoseconds of delay induced by delay assembly 180. As a result, the pulses from the pulse amplifier can be selectively amplified, and both At least 2 and up to about 10 output pulses with the same peak power are pulsed Each input pulse to multiplier 102 is generated.

Therefore, in pulse processing system 26, a single pulse from an excimer laser is are shortened to form multiple ultrashort pulses. excimer laser Each input pulse from produces a burst of pulses, and each burst is the duration of the input pulse 0 side produces approximately 10 output pulses with a total duration approximately equal to for a duration of about 5 to about 8 nanoseconds and an energy of about 40 to about 50 millijoules. Single excimer pulses of energy can be used, each pulse having approximately 10 to It has a duration of approximately 15 ps, and the pulses are spaced approximately 130 ps apart. energy level of at least 300 microgenius per pulse. The output pulses have a near-Gaussian transverse spatial distribution. Output pulse energy – by increasing or decreasing the number of amplifier assemblies used in the amplifier system. , changes to provide enough energy to form a plasma in the target can be done.

The dye amplifier cell 90 and shortener cell 64 shown in FIG. Replenishment of dye solution in a direction transverse to the direction and transverse to the direction of the input main pulse It is configured to circulate the minutes. However, in some cases, the dye solution may be supplemented. It is also possible to use a dye cell that is sealed at both ends to provide a fixed supply without being filled. It is. If circular flow is required, the windows of each cell are joined together along its sides; Appropriate connections and piping should be provided at the top and bottom of each cell to allow for replenishment of dye solution. I will do it.

3. Beam emission and imaging system The purpose of the beam emission system 28 is to exits the processing system 26 onto the target at an irradiance high enough to generate a lasma. The force pulses 180 are directed and bundled. This operation is the output pulse a step of expanding and collimating the output pulse, and a step of expanding and collimating the output pulse. and the step of bundle the straw onto the target through the objective lens. Operator is in state The imaging signal is bundled onto the target so that the imaging A signal generated from a target as a result of a signal, typically reflection imaging The signal is subsided. For precise control, preferably the laser radiation pulse and The focal plane of the laser pulse and the imaging beam are collinear. It is the same as the focal plane of the signal. Imaging signal and laser pulse are collinear and passes through the same objective lens, so the imaging system and beam emitting There are no alignment issues with the system.

In the first and sixth zones, the output laser pulses 180 from the processing system 26 are The image is expanded and collimated by an expander/collimator 184. beam Spander/collimator 184 has a narrow focal length with anti-reflection coating. A plano-concave entrance lens 186 with a long distance and a plano-convex exit lens 188 with a relatively long focal length are used. Contains. The concave surface of the input lens 186 and the flat surface of the exit lens face outward. There is. The distance between the two lenses is determined by the expander/collimator 184. is adjustable to control the dimensions of the beam 190.

Similarly, by adjusting the distance between the two lenses, the focal plane of the pulse can be adjusted to Adjust the focus of the pulse on the target so that it is flush with the fish plane of the scanning system. It is possible to do so. Beam expander/collimator 184 is the final straw bundle Increase the beam diameter to a dimension that substantially fills the lens, thus making the final straw bundle lens Maximize the effective f-number of. This results in a high conical beam spot and a minimum diameter beam spot. You can get Preferably ↓; the ratio of the focal lengths of the entrance and exit lenses is the beam diameter at least about 1:10 to increase the beam diameter by a factor of 310, preferably by a factor of 20; That is, 1 to 21. The ratio is about 1:20 so that the diameter of the glue is in the order of 20 to 40 mm. ．． In order to maintain the lens spacing at a relatively small value in this way, commercially available microscope pairs are used. A compound lens system such as an object lens may be used.

According to aspect-5 of the present invention, the input pulse has a diameter of about 1 to 2 mm, and the corresponding The output pulse 190 has a diameter of approximately 38 mm. For this purpose, the entrance lens 18 6 may have a focal length of about -20- and a diameter of 131, and the exit lens 188 has a diameter of about 3 It has a diameter of 8ml and a focal length of approximately 190+e-. The two lenses are approximately 17 01 spacing.

The expanded and collimated light 190 is directed to a positioner or aiming point by a mirror 198. is sent to system 28. The sight 28 beams to effect the desired movement of the focal point. and a suitable deflection element inserted into the beam passageway. Aiming system 28 is X , three mirrors 202^ to control the position of the focal point in the Y and Z axes, 202B and 202C. The laser beam is initially parallel to the Y axis, Deflected 90° three times in succession. First, as shown in FIG. 2^ to be deflected parallel to the χ axis, and then deflected parallel to the Z axis by mirror 202B. The mirror 202C further advances downward along an axis parallel to the Y axis. be biased to do so. The position of the mirror, i.e. the position of the focal point, can be adjusted as required. a control system 36 that may be operated by a hand or foot control (not shown); More controlled.

The properly aimed beam is then focused by a focusing objective 206. suitable The effective speed of the standard JLOM camera lens 206, or Determined by the cone angle at which the beam is focused. The beam passes through the straw bundle lens 206. The positions where the light is focused are called "focal points" and "spot positions." The spot size is It has a diameter proportional to the effective f-number of the focusing objective lens 206. A sufficiently small spot To achieve this size, the focusing lens 206 should have a cone angle greater than about 16°. The velocity is high enough such that the angle is at least 20° and optimally at least 30°. . Correspondingly, the focusing lens 206 is preferably less than about 3.5, more preferably has an f-number of less than 2.8, optimally about 1.4, so that the beam is substantially 1. Advantage 3 of the present invention expanded to meet the requirements! ! f/1.4 lens used in For lenses, the nominal cone angle is 39.3°. A circle passing through the focusing objective lens 206 Due to the large cone angle, it is possible to obtain small transverse spot sizes. child This maximizes the irradiance at the spot location and provides relatively low total energy operation. becomes possible. Additionally, lower total energy at axial or transverse distances from the focal point operating at high irradiance and high irradiance fall rates, making it possible to operate at a distance from the target area. damage can be minimized.

An optical system or imaging system 30 provides a focal point for viewing by an operator. It functions to provide the viewing monitor 32 with an enlarged image of the surrounding area. image The lighting system 30 includes a light source 220 and a portion of the light from the light source 220 that directs a portion of the light from the light source 220 into a laser editing pattern. a beam splitter 222 for directing the beam along the path of the beam. . Unsegmented imagen that should be collinear with the incident laser radiation pulse A portion of the optical light 225 is collected at a first light dump assembly 224 . image The scanning light is applied to the target along with the laser radiation pulse by the positive stainer system 34. and is focused on the target area by the focusing objective lens 206. Image A part of the beam splitter 225 is reflected from the target and sent to the second beam splitter 225. is reflected into the imaging lens 230 and passes through the lens to the eyepiece 23. 2 and is sent to the image intensifier 234. Second beam splitter 225 The light that is not sent to the imaging lens 230 is sent to the second light dump assembly. It can be dumped into the yellowtail 227. Imaging lens 230 has 50 to 3001 zoom The eyepiece 232 may be a 20-magnifying lens. Image The lens 230 forms a real image in cooperation with the straw bundle objective lens 206, and the real image is further multiplied by an eyepiece 232, which can be a silicone multiplication target tube. is projected onto the active area of image intensifier 234. The image is adjusted by an image intensifier. A proper image processing bag! (for example, the viewing monitor 32).

The second beam splitter 225 and the imaging lens 230 are separated by a second A polarizer 229 is arranged. The second polarizer is 90% relative to the first polarizer 93. It is located at a rotation angle of °.

Light source 220 is preferably a collimated white light source.

Other light sources can also be used, e.g. slit illumination, forward illumination, fiber optics. A plastic tube, an axial illumination system as described above, or a combination thereof can be used.

Beam splitter 22 used to direct visible light from light source 220 2 and a beamform used to direct visible light to lenses 230 and 232. The splitter 225 is a broadband beam splitter and a laser beam splitter. - transmit about 85-80% of the beam and reflect about 96% of the visible light. That is, Bee The mus splitter transmits the laser pulse traveling towards the target and Most of the visible light that enters the target is reflected. A suitable beam splitter is Newpoirt C located in Fountain Valley, Fornia Model No. 20040 NCI from organization It's on sale.

When operating the system, the operating wavelength should be determined according to the common name rather than the absorption of the target itself. The material is selected based on the absorption rate of the material absorbed by the target. Wavelength is non-target Maximize target penetration and beam energy to minimize damage to the target. selected to ensure that the bulk of the energy reaches the target.

IL color Cold JLLL In this embodiment, the position of the focal point 77 of the pulse shortener 64 depends on the duration of the output pulse. Show how it affects you.

using a XeCl excimer laser at a wavelength of 308 nm for about 5 to about 8 nanoseconds. An input pulse was generated having a duration and an energy of about 3 to about 4 mj. Ma Using ichromator-controlled plano-convex straw bundle lenses, 1.25mm thick front and rear The pulses were bundled into a pulse shortener 64 having a partial window. The window is made of quartz, 1 They were arranged at an interval of 0 mm (distance N from inner surface to inner surface). front & rear windows Both were placed perpendicular to the axis of the input pulse. The cell used was Be1 from West Germany. Hellma 5uppersil UV quartz cell obtained from ls-a Cmbb It is le. The dye used in the cell was BBQ (Table 2), the focal point and inside the front window. Detect the number of output pulses and pulse duration by changing the distance between the side surface and the Ta. The results are shown in Table 1.

Pulse pre-old, is Pulse L! iJka's pulse's PItIlζLL store Distance from front window Output pulse Note d(■ Time a(Pico) 3.00 2000 multiplied pulse 3.35 1600 strong secondary pulse 3.53 800 Small secondary pulse 3.85 600 single Gaussian pulse As is clear from Table 1, when the focal point is significantly close to the front window, non-Gaussian A heavy pulse is generated. If the focal point is placed at a distance of 3.851 from the front window, the pulse The duration of the flash was reduced by approximately 90%.

m-engineering The system shown in Figure 2 was tested. Input laser is B1, Masatine Sett. The model 12400 was obtained from Questek, where 11erici is located. Ta. The gas composition of the laser 42 is 30 mbar BCI (5%) in helium, 2 0 mbar xenon and 2000 mbar helium. excimer Each output pulse of the laser has 40-60 millijoules of energy and 5-8 nm Second duration (FWHM), and with a wavelength of 308 nanometers! λ table Color snoring warm bar Σ辷! two 1st fiiiia 54A 10 BBQ")ex>/B7->(50150 ) 1.5th Z no short taa! ;4B　lR59o'2koxy)-ru503rd Shortener 54CI R610'ko' 19/-1'v 50 First amplifier 9 0A 10 BBQ)X! #j/-) (50150) 1 Second amplifier 9 0B 10 R590 engineering 9/-le 5 3rd amplifier 90C, D, E, F 10 R610 Ethanol ° 2.5 (1) 4,4 °゛-bis[(2-butyloctyl ) Oxyco-1,1': 4'', 1''=4'', 1''-quaterphenyl (2) Ethyl o-[6-(ethylamicar 3-(ethylimino)-2,7-dimethane) Chil 3-toxanthene-9-ylcobenzonite chloride (3) [9-(o-carboxyphenyl)-6-(diethylamine)-3H- Xanthine-3-ylidenecoethylammonium chloride The dimensions of the dye cells and dyes used in the pulse shortener and amplifier are shown in Table 2. A quartz dye cell from Ellma was used.

The dye used in the amplifier 90 is such that the optimal absorption wavelength of the dye solution is the wavelength of the pumping beam. selected to match the length. Color T of shortener 54: optimum absorption of bath solution, dye solution The wavelength was chosen to match the wavelength of the incident main pulse.

Table 3 shows the focal length and diameter of the focusing lenses used in the processing system for straw bundles. Instead of using a plano-convex lens, you can use a biconvex lens or a meniscus lens. Both were possible. All lenses are constructed from quartz as before.

Table 3 Straw bundle lens parameters Focal length diameter Lens S Showa (In-(In-) First shortener assembly 62^21 Second shortener assembly 62B 2 1 Third shortener assembly 62C11 First amplifier assembly 88^32 Second amplifier assembly 88B 3 2 Third amplifier assembly 88C32 Fourth amplifier assembly 88D 3 2 Fifth amplifier assembly 88E 3 2 Sixth amplifier assembly 88F 3 2 Neutral band filter 66 is It reduced the energy of the russ by about 50% and had an outside diameter of 2 inches.

Adjustable optical delay line assembly 180 provides a path length of approximately 2 feet; The main pulse was delayed by approximately 2 nanoseconds.

The energy of the incident beam entering the beam splitter The beam subrirradder shows the percentage of light that the liter splits or redirects in Table 4. - has a visible light transmittance of at least about 90% and a reflection of the pumping beam wavelength. It is dichroic with a rate of 100%. All mirrors are reflective mirrors with a reflectance of over 95%. There are many.

The pulse multiplier 102 was manufactured as shown in Section 5. The front and rear windows are each thicker. It was 172 inches long, made of glass, and had an anti-reflection coating on its outer surface. Ga Las is CVI, Inc., located in Ibuquerque, Mexico. Use catalog number EW4-4050C (^R-85%) commercially available from Ta. The inner surface of the glass has a reflective coating that reflects 85% of the incident light. . The front and rear windows were arranged with an opening of 11.4 mm. In the space is Minnesota, St. , commercially available under the trade name Fluo-rinert from 3M, Paul It was filled with perfluorochemical network active liquid at a pressure of 2.5 psiE. both windows It was curved inward with a radius of curvature of approximately 2 kT&.

! j”1 Beam Subbut -〇〇》 Beamsbut・-昭　゛゛(0寞 1st 50th 10th 1st stage amplifier 84^4 2nd stage amplifier 84B 10 3rd stage amplifier 84C20 4th stage amplifier 84D 20 5th stage amplifier S4E 30 *The amount by which the splitter 50 turns toward the third reflector 54 Table 5 shows the beam parameters for each position along the beam path. From table 5 showing the number of pulses in position, pulse duration and pulse energy. As a matter of fact, it has a duration of about 6000 picoseconds and about 4000 microjoules. The input pulses with energy each have a duration of about 10 ps and a duration of about 350 ms. This was converted into approximately 10 pulses with a pulse energy of 1,000 liters.

Additional 5,% Pulse duration Pulse energy Pulse (Pico (My Rojoule) Input (44) 1 5000 4000 After first reduction 5 1 600 4 After the first amplifier 1 600 90 After second shortening 5 1100 ・1.5 After the second amplifier 1 100 25 After third shortening 5 1 10 1.5 After the third amplifier 1 10 30 After the third multiplier 10 10 0.01 After the fourth amplifier 10 10 2.5 After 5th amplifier 10 10 35 After 6th amplifier 10 10 350 The expander/collimator 184 has a concave surface facing the input beam side. The input lens is a plano-concave lens 186 with a focal length of III and a diameter of 13 mm. 186, with an outwardly facing planar surface and a focal length of i5:oI and about 5 A plano-convex lens with a diameter of 0.01° is used as the exit lens 188. did. The distance between the two lenses was allowed to be rsW and was set to 170 mm. incident The beam shall have a wavelength of 595 nanometers and a diameter of 21 nm, with a diameter of 38 nm. was expanded to provide a collimated near-Gaussian beam with a diameter of .

The straw bundle lens 206 is manufactured by West Germany's Carl Zwiss and has the product name Hass-el. f/1.4 lens speed, commercially available under b1id catalog number 102150; A camera lens with a back focal length of 70 mm was used.

The imaging lens 230 has a velocity of g<,"r and a focus of 5(1-300mm+ A N1kon zoom lens with a distance was used. The eyepiece lens 232 is Nik on20mm f/2.8 lens. N1kon F-C mount adapter The eyepiece 232 is attached using a Cohu™ silicon multiplier Vidacom (vi claeom) connected to a camera-type image intensifier 234.

The system was tested with sutures having a diameter of 22 &lII in various tissues. system delivered approximately 15 bursts per second with 1o pulses per burst.

The first pulse tested was an opening of about 200II*. The 0 cone angle was wide, about 3 It was 5°. The energy of each pulse was less than approximately 1 millijoule; A spot of about 2° was generated, and a plasma was formed.

The tissue used was a postmortem eye bank eye, and the cornea and extraocular muscle capsule were processed. I used something. The area to be targeted is 10-0 fibers in the medial stroma of the cornea. An iron suture was passed, and the muscle was identified by passing a 6-0 black silk thread through the sheath surface layer.

In the cornea, the suture is placed in a 4-part pine tress condition, and the suture is placed in the suture loop at the time of ligation. I made it so that it has a certain amount of tension. The laser and m; bundle the straw at the sewing thread level, and The straw was ignited so as to align it with the positive i and bundle the straw. Subsequent laser bursts etch It was applied in a straight line at an angle of 90° to the area covered.

Finally, the suture was cut with a laser beam. Place the entire laser burst into the corneal stroma , or in the case of muscle B sheath, maintained on the surface of the suture. After death, normal transparency is lost. In order to target the muscle sheath, we must remove the upper layer of abdominal congestion. won. The treated tissues were removed together and treated with 2% glutyraldehyde and form. Fixed in 2% aldehyde and sealed so that it can be observed with an electronic or optical microscope. did.

Tissue processing after delimitation for electronic microscopy examination is performed in 0.15M sodium cacodylate N solution. of osmium was used. nNM, staining for electron microscopy of corneal samples is quenched. This was done using lead acid and uranyl acetate. Hematoxylin and and eosin dye was used. Labeled sutures allow pathologists to identify processed areas in serial sections. I was able to confirm the area accurately.

Additionally, the suture cord provides a control lesion adjacent to the dehiscence created by the laser. Ta.

The maximum calculated laser power density was detected at the target tissue. The test is at 20 hertz. and the speed was kept constant to form a linear lesion at the selected depth. . Cut the 22t+- suture using a 211II burst and determine the depth of the burst. changed in some places. All samples were 595 nm with a pulse duration of 10 ps. It emitted a wavelength of meters with a cone angle of 30-40°. This is the spot size of 21 The radiation density was approximately 1015 watts/e1 m'.

Place a 10-0 monofilament nylon suture in the medial stroma of each of the two eye bank corneal specimens. The sutures were cut using laser treatment and these samples were subjected to optical and electron microscopy. More tested.

Optical intermittent microscopy shows that the thread cords, and finally the sutures in serial sections, are located in the laser-blocked area. It disappeared from the area, and a cavity without sutures was formed in the medial stroma. This processing zone The margin is uneven, and the posterior margin, which borders the deep cortex, is dense and slightly posterior. It had arch-shaped characteristics. The epithelium of all samples was completely exposed, which is probably due to This is thought to be an artifact due to postmortem acquisition of tissue. Just before the processed area Bowman's membrane, Descemet's membrane, and corneal endothelium can all be treated with laser at the optical or microscopic level. It was discovered that there was no alteration due to medical treatment.

The 111II section of plastic encapsulation material was placed in the stroma away from the laser treated area. Both sides of the suture showed a uniform lamellar structure.

On the other hand, non-uniform density of stroma was observed in the laser treated area. Laser treatment area Electron microscopy examinations performed on suture material in the intermediate cortex away from the lamellae A suture cord was observed in between. In the laser treated area, the normal collagen spermatozoa of the lamellae The structure was divided. Collagen fibers are destroyed and there is a normal A large amount of electron-dense debris was present. Larger T9 dense fragments are suture material It seemed to be the remains of. Collagen damage is 4 or more in areas far from the suture cords. lamellae (i.e. 20×40 pm).

When examined by optical microscopy, the extraocular muscle armor lacks conjunctiva and is due to post-mortem emulsion. It was peeled off and the oral surface could be treated directly. A predetermined distance from the laser treatment In the region of the distal key, there is a regular, well-defined oral connective tissue sheath, probably corresponding to Tenon's capsule. was closely attached to collagen. The area treated with the laser is marked with 6- There was an intraoral cavity in which silk sutures were placed and removed to prepare thin sections for tissue pathology analysis. It was clear that there were two distinct transformations of the braided sheath connecting the pus sheath.

Treated cornea and muscle B sheath 3 tested by optical and electron microscopy, 595I In operation, the system of the present invention ablate the corneal stroma and superficial extraocular muscle sheath. has been proven.

Small spot size and high power density create well-defined lesions. minimize the blast effect (damage zone). Observe corneal sections where the epithelial and endothelial layers of Bowman's membrane or Descemet's membrane or their respective No laser damage was observed. In the muscular oral sheath, only the majority of the superficial layer is ruptured. the deeper layers are protected by energy absorption by opaque tissue. there was. Since the power density and spot size can increase exponentially, high power It is expected that selectively deep lesions will be obtained that are proportional to the density and selected spot size. It is thought of. In refractive surgery, intrastromal ablation can be used to remove the anterior optic surface. It is possible to form a new corneal curvature2 while maintaining it as it is, and the results are remarkable. For example, if corneal tissue from the pericorneal area is removed in a gradient shape on a plane, the central Corneal curvature increases and hyperopia can be corrected. Conversely, if we remove the gradient layer from the center It can correct myopia, and when removed in a fan shape, it can correct astigmatism.

Current muscle nail surgery is even less accurate than corneal surgery, so using the system of the present invention It is extremely suitable for use. Transconjunctival, non-invasive and titratable A simple and easily repeatable muscle weakening or strengthening procedure can be performed.

By slightly varying the wavelength, spot size and power density, the extension (by non-thermal ablation) or reinforcement (gradient) to a depth determined by the The tissue can be ablated (by thermal ablation).

4.LL The laser system of the present invention has many applications. physical and scientific purposes, such as obtaining information about the structure and properties of molecules. and chemistry, and provides instruments suitable for investigating plasma-plasma interactions. can be used to

Many applications in biological and medical fields include systems for diagnostics and laser surgery. There is. The system can be used as a scalpel to treat separated M membranes, vitreous incisions , for W4 membrane incision, as well as for treating diabetic retinopathy, as well as on the eyelids. It can be used for photocoagulation to remove foreign bodies and polyps.

The system does not cause obvious damage to the previous layers (epithelium, Bowman's membrane and surface stroma) and The wound is concentrated on the cornea within the cortex without damaging the deep cortex, Descemet's membrane, and corneal endothelium. It is possible to form scars. Corneal and significantly improve refractive and cataract surgery.

The laser system of the present invention can also be used for intraoral surgery such as removal of papillomas or tumors. can be used. It may also be used to treat bleeding lesions in the gastrointestinal tract. Dermatology In order to remove phlegm and treat certain vascular diseases such as wine hemangioma. This laser system can be used to

The laser system of the present invention can be used for materials such as welding, cutting, drilling, surface treatment and alloying. It can also be used for food processing.

High precision and minimum precision such as welding of microelectronic elements and drilling of hard materials Particularly useful in applications requiring thermal damage. Also, microelectronics and cutting and drilling ceramic materials for resistive trimming.

Additionally, it may be useful in telecommunications.

Laser systems are also suitable for applications requiring virtually continuous high-energy output pulses. useful on the way. Multiple pulse multipliers arranged in series and parallel with subsequent amplification By using a device, it is possible to obtain multiple high power pulses.

A notable advantage of the system of the invention is that it is mechanically simple. and can be easily aligned with the patient. All elements of the processing system are placed one behind the other in the system so that the devices can progress through one continuous forward pass. It is designed to. Therefore, how many places can the treatment system be applied to a relatively small area under the patient? It is possible to realize a compact laser system that can be placed in Wear.

Two significant advantages of the system of the present invention are that it contains tissue between the laser source and the target. Surrounding group! ! Accurately cuts in areas as narrow as 1μ without damaging the surface. Where possible, ultrashort pulses cause minimal damage to surrounding tissue.

In addition, pulse multipliers allow this precision laser to be used in applications such as laser scalpels. – It is possible to obtain a sufficiently large damage zone in a short time to enable the system It is. Moreover, the amplitude does not change substantially between pulses and bursts.

Additionally, the system can perform cuts regardless of the absorption rate of the target zone; It is possible to cut substances that could not be cut efficiently with conventional methods. . Additionally, simple changes can be made, such as by changing or adjusting the dyes used in the dye cell. A single laser system can be used on a wide range of materials by simply changing the output wavelength. I can do it.

The imaging light and laser beam are on the same line and the image is separated from the target. Because there is virtually no backscatter in the imaging system, the system is easy to use and can be easily targeted to the desired target zone.

Pulse multiplier allows cutting to widths and lengths equal to or smaller than conventional cutting techniques. It is possible to form the beam at the same time, and it is possible to form It is possible to make a much shallower cut than is possible. Furthermore, accurate tunneling Detailed Description of the Invention Detailed Description of the Invention With reference to one or more specific barrier embodiments in which the However, other embodiments are also possible. For example, an excimer may be used as the input laser. Double wave or triple wave Nd:YAC laser depending on the application without using a laser There are times when it is more appropriate. Additionally, longitudinally pumped dye amplifier cells It is also possible to use a laterally pumped dye cell amplifier without using It is. Therefore, the spirit and scope of the present invention is limited to the preferred embodiments described herein. Shouldn't.

Special table Hei 1-502562 (21) X shi f international search report 1111^"11"' P-/υSε7100966-Sign table flat 1-5025t i2 (22)

Claims (29)

[Claims] 1. A method for forming a plasma in a target, the method comprising: (a) a stage for generating the main laser radiation pulse; and (b) (i) each stage for generating amplified spontaneous radiation. at least one pulse shortener for shortening the duration of the main pulse by outputting the main pulse; a series of shorteners/amplifiers including at least one pulse amplifier that amplifies the exciting a first pulse shortener of a first stage consisting of; (ii) the first pulse amplifier in the first stage without substantially changing the amplification between pulses; amplifying the shortened pulses generated from the pulse shortener; (iii) passing the laser radiation pulses generated from each stage to the pulse shortener of the next successive stage; The shortened pulses generated from the pulse shorteners of each stage are A stage in which the amplification is amplified by a pulse amplifier in stages, with the amplification remaining virtually unchanged between pulses. and This reduces the duration of the main pulse in the pulse processing zone and removes it from the pulse processing zone. such that the output pulse has a duration of less than 100 ps and a near-Gaussian distribution. (c) whether the target is absorbing or non-absorbing to the output pulse; Regardless of the small enough in the target to obtain an irradiance of at least 1013 watts/cm2 focusing the output pulses by a focusing means to a small spot size. 2. A method for forming a plasma in a target, the method comprising: (a) generating at least one primary laser radiation pulse; (b)(1)(i) at least one pulse in which each stage shortens the duration of the main pulse; a pulse shortener and at least one pulse amplifier for amplifying the main pulse. exciting a first pulse shortener of the first stage consisting of a shortener/amplifier; (ii) ) the shortened pulse generated from the first pulse shortener in the first stage pulse amplifier; (iii) amplifying the laser radiation pulses generated from each stage to the next series; The shortened pulses generated from each stage pulse shortener are sent to the next stage pulse shortener. a step of amplifying it by a pulse amplifier in that stage before sending it to the stage of (2) shortening the duration of the main pulse in the shortening zone by a pulse multiplier; A pulse multiplier that generates multiple pulses spaced apart in time for each input pulse; multiplying each shortened pulse generated from a later pulse shortener/amplifier stage; 3) includes at least one short pulse amplifier to generate high power output pulses; an amplifier zone that amplifies at least a portion of the spaced apart pulses so that the output pulse is 1 a processing stage with a duration of less than 00 ps and a near-Gaussian distribution; to generate a suitable output pulse to focus into the target, including the processing each main pulse in a pulse processing zone; (c) Relation to whether the target is absorbing or non-absorbing to the output pulse. at least 1 in the target to form a plasma in the target. A small enough spot in the target to obtain an irradiance of 0.13 watts/cm2. focusing the output pulses by a focusing means to the same dimensions. 3. The target is non-absorbing to the output pulse, preferably the target is animal tissue, and the output pulse passes through other animal tissues before reaching the target tissue. The method according to claim 1 or 2, wherein the method comprises: 4. Claim 1, wherein the target tissue is substantially transparent to the focused pulses. The method according to any one of 3 to 3. 5. each main pulse has a duration of at least 1 nanosecond, preferably 5 nanoseconds; The duration of each corresponding pulse generated from the last shortener/amplifier stage is 100 pm. Any of claims 1 to 4 in which the duration is less than 10 ps, preferably less than 50, 10 or 1 ps. The method described in item 1. 6. The duration of each pulse generated from the last shortener/amplifier stage corresponds to the main pulse. 6. According to any one of claims 1 to 5, the duration of the pulse is less than about 1/100 of the duration of the pulse. the method of. 7. At least a portion of the pulses are collimated to obtain a near-Gaussian distribution of the output pulses. 7. A method according to any one of claims 1 to 6, comprising the step of: 8. A method for shortening the duration of laser radiation pulses that uses amplified spontaneous radiation. Laser radiation incident on the dye solution to generate radiation in the dye solution by The method includes the step of focusing the pulse to a focal point in a dye solution, where the dye solution is The dye solution is contained in a device containing a front window and a rear window. The front and rear windows have inner surfaces, and the front window is incident on the dye solution. The front and rear windows are transparent to at least a portion of the laser radiation pulse, and the front and rear windows are transparent to the generated radiation. The front window reflects a portion of the incident generated radiation to a focal point. , the generated radiation is output pulsed so that the generated radiation is not substantially reflected from the rear window to the focal point. As it passes through the rear window, each incident radiation pulse is focused into a single beam of shorter duration. The method is located between the front and rear windows so as to have different output pulses. 9. the duration of each output pulse is less than about one-half the duration of the respective input pulse; 9. A method according to any one of claims 1 to 8, preferably less than 1/10. 10. According to any one of claims 1 to 9, the spot size is less than 10 μm. the method of. 11. An apparatus for reducing the duration of a laser radiation pulse, the apparatus comprising: (a) a dye solution capable of absorbing energy from an incident radiation pulse; (b) Both the anterior and posterior windows have inner surfaces, with the anterior window entering the dye solution. Front and rear windows capable of transmitting at least a portion of the laser radiation pulse means for containing a dye solution containing; (c) The color is passed through the front window to generate radiation into the dye solution by amplified spontaneous emission. Optically focuses the laser radiation pulse incident on the elementary solution to a focal point between the front and rear windows. and an optical means placed in front of the front window for bundling the front and rear windows. The window is substantially transparent to the generated radiation and the front window blocks laser radiation A part of the incident radiation is reflected to the focal point so as to eliminate the stimulated emission, and the output is generated. The radiation generated from the rear window to the focal point is output pulsed so that virtually no radiation is reflected. through the rear window, the focus is such that each incoming radiation pulse is a single, respective pulse of shorter duration. A device placed in a position between the front and rear windows to have an output pulse. 12. The duration of each output pulse is less than approximately one-half the duration of each input pulse , preferably less than 1/10. 13. so that the focal point is closer to the inside surface of the front window than to the inside surface of the rear window. The distance between the focal point and the inner surface of the front window is preferably two inner 13. A device according to claim 11 or 12, wherein the distance between the surfaces is at least 30%. 14. A device for forming plasma in a target using ultrashort wave pulses, , (a) means for generating a plurality of main laser radiation pulses; and (b) corresponding short pulses. means for shortening the duration of each main pulse to form a compressed output pulse. wherein the shortening means includes a series of shortening/amplifier stages, each stage substantially – Reduces the duration of each main pulse by amplified spontaneous emission without radiation Both pulse shorteners ensure that there is virtually no pulse-to-pulse variation in amplification from pulse to pulse. and at least one pulse amplifier for amplifying each main pulse, with a stage for each main pulse. so that the laser radiation pulses generated from one stage are sent to the pulse shortener of the next successive stage. The pulses generated from the pulse shortener at each stage are sent to the next stage. The pulse amplification of the stage is adjusted so that there is virtually no pulse-to-pulse variation in amplification between pulses before (c) the target is amplified by the output pulse; Forming a plasma in the target, whether absorbing or non-absorbing to obtain an irradiance of at least 1013 watts/cm2 in the target. Focusing hand for focusing the output pulse to a sufficiently small spot size in the target A device comprising a stage. 15. The duration of each pulse generated from the last shortener/amplifier stage corresponds to 15. Any one of claims 11 to 14, which is less than about 1/100 of the duration of the pulse. The device described in. 16. In order to obtain a near-Gaussian distribution of pulses incident on the optical means, the laser radiation pulse 16. Any one of claims 11 to 15, further comprising means for collimating the gas. The device described in. 17. The pulse shortener operates by amplified spontaneous emission without lasing and reduces the output pulse. 17. Any one of claims 11 to 16, wherein the Equipment described in Section. 18. According to any one of claims 11 to 17, wherein the spot size is less than 10 μm. The device described. 19. A method for forming a plasma in a target, the method comprising: (a) a stage for generating the main laser radiation pulse; and (b) (i) each stage for generating amplified spontaneous radiation. at least one pulse shortener for shortening the duration of the main pulse by outputting the main pulse; a series of shorteners/amplifiers including at least one pulse amplifier that amplifies the exciting a first pulse shortener of a first stage consisting of; (ii) The shortened pulse generated from the first pulse shortener is transmitted to the first stage pulse amplifier. The signal is amplified by the pulse shortener in the next successive stage and sent to the pulse shortener in each stage. amplifying the shortened pulse; This reduces the duration of the main pulse in the pulse processing zone and removes it from the pulse processing zone. the output pulses have a duration of less than 100 ps and a near-Gaussian transverse spatial distribution a step of making the (c) Relation to whether the target is absorbing or non-absorbing to the output pulse. at least 10% in the target to form a plasma in the target. A spot small enough in the target to obtain an irradiance of 13 watts/cm2 focusing the output pulses in dimension with a focusing means. 20. Contains at least one short pulse amplifier to generate high power output pulses including the step of amplifying at least a portion of the pulse in an amplifier zone containing the output power. The duration of the pulse is less than 1/10 of the main pulse duration and the near-Gaussian transverse spatial distribution 20. The method according to claim 19, wherein the method comprises: 21. For forming plasma in animal, preferably human tissue targets a pulse processing zone in which the output from the pulse processing zone is approximately 1/100 of the duration of the main pulse. has an output pulse duration of , and targets the output pulse from the focusing means. the pulsed Claim 19: passes through other animal tissues before reaching the target animal tissue. or the method described in 20. 22. A method for forming plasma in a human tissue target, the method comprising: generating a main laser radiation pulse having a duration of 5 to about 8 nanoseconds; 22. A method according to any one of claims 19 to 21. 23. A method for forming plasma in an animal tissue target, the method comprising: (a) generating a main laser radiation pulse with a Nd:YAG laser; (b) (i) each stage reduces the duration of the main pulse by amplified spontaneous emission; at least one pulse shortener and at least one pulse shortener for amplifying the shortened main pulse. Excite the first pulse shortener of a stage consisting of a series of shorteners/amplifiers including and the step of (ii) the shortened pulse generated from the first pulse shortener in the first stage pulse amplifier; (iii) amplifying the pulses; and (iii) amplifying the laser radiation pulses generated from each stage. The shortened pulses generated from each stage pulse shortener are sent to the next successive stage pulse shortener. a step of amplifying the pulse This reduces the duration of the main pulse in the pulse processing zone and removes it from the pulse processing zone. the output pulses have a duration of less than 100 ps and a near-Gaussian transverse spatial distribution a step of making the (c) amplifying at least a portion of the pulse in an amplifier zone to generate an output pulse; and the step of (d) Relation to whether the target is absorbing or non-absorbing to the output pulse. at least 10% in the target to form a plasma in the target. before reaching the target animal tissue to obtain an irradiance of 13 watts/cm2. output pulses that have passed through other animal tissues to less than approximately 10 μm in the animal tissue target. focusing by a focusing means to a spot size of method including. 24. generating a main laser radiation pulse of at least about 1 nanosecond duration; The output pulses from the processing zone have a near-Gaussian transverse spatial distribution and a main pulse duration. 24. The method of claim 23, wherein the method has a duration of about 1/10 of that of . 25. A claim in which the main pulse has a wavelength of about 300 nanometers, preferably more than 300 nanometers. 25. The method according to any one of paragraphs 19 to 24. 26. The step of shortening the duration of each main pulse is carried out by amplified spontaneous emission into the dye solution. In order to generate radiation, the laser pulse incident on the dye solution is focused at a focal point in the dye solution. Includes a bundling step in which the dye solution absorbs energy from the incident radiation pulse The dye solution is contained in a device with a front window and a rear window, and The windows have inner surfaces regularly spaced from each other, and the front window is in the dye solution. The front and rear windows transmit at least a portion of the main pulse and are substantially transparent to the radiation generated. The front window reflects some of the incident generated radiation to the focal point, and the generated radiation exits. The generated radiation is transmitted through the rear window as a force shortening pulse and is not reflected from the rear window to the focal point. The focal point is that the incident main pulse has a single respective output shortening pulse of shorter duration. Claims 1 to 10 or 1, wherein the window is located between the front and rear windows so as to 9 to 25. 27. The focal point is located closer to the inner surface of the front window than to the inner surface of the rear window. preferably at least 30% of the distance between the respective inner surfaces of the windows. 27. The method of claim 26, wherein the method is located at: 28. The step of focusing the main pulse is focused to control the duration of the output pulse. 28. The method of claim 27, further comprising the step of moving the optical means for selecting the location of the point. Method described. 29. sending the output pulse to the target via the beam emitting means; focusing the pulsed pulse on the target and viewing the pulsed target in this way. as claimed in any one of claims 1 to 10 or claims 19 to 28, comprising the step of How to put it on.