KR20070085548A - Efficient micro-machining apparatus and method employing multiple laser beams - Google Patents

Abstract

A laser beam switching system (50) employs a laser (52) coupled to a beam switching device (58) that causes a laser beam to switch between first and second beam positioning heads such that while the first beam positioning head (60) is directing the laser beam to process a workpiece target location, the second beam positioning head (62) is moving to another target location and vice versa. A preferred beam switching device includes first and second AOMs. When RF is applied to the first AOM (72), the laser beam is diffracted toward the first beam positioning head, and when RF is applied to the second AOM (74), the laser beam is diffracted toward the second beam positioning head. A workpiece processing system (120) employs a common modular imaged optics assembly (122) and an optional variable beam expander (94) for optically processing multiple laser beams.

Description

Efficient MICRO-MACHINING APPARATUS AND METHOD EMPLOYING MULTIPLE LASER BEAMS

The present invention is a Continuation-In-Part (CIP) of US Patent Application No. 11 / 000,330, filed November 29, 2004, and the CIP (Continuation) of US Patent Application No. 11 / 000,333, filed November 29, 2004. -In-Part), the latter is the CIP of US Patent Application No. 10 / 611,798 filed on June 6, 2003.

BACKGROUND OF THE INVENTION The present invention relates to lasers, in particular increasing workpiece throughput by alternately switching a single laser beam in two or more beam paths so that one of the beam paths is used to machine one workpiece while the other beam The path is to a method and apparatus that is positioned for the processing of other workpieces.

Lasers are widely used in a variety of research, development and industrial operations, including inspection, processing and micromachining of a variety of electronic materials and substrates. For example, to repair Dynamic Random Access Memory (DRAM), a laser pulse cuts an electrically conductive link to disconnect the faulty memory cell from the DRAM device, and then replaces the spare memory cell to replace the faulty memory cell. It is used to activate it. Because the faulty memory cells requiring link removal are placed randomly, the links that need to be truncated are randomly located. Thus, during the repair of the laser link, the laser pulses are ignited in a random pulse interval. In other words, laser pulses move well over a wide range of PRFs rather than at constant Pulse Repetition Frequency (PRF). In order for the industrial process to achieve more production throughput, the laser pulses are ignited at the destination link without stopping the scanning mechanism of the laser beam. This production technique is referred to in the industry as On-The-Fly (OTF) link processing. Other common laser applications use laser pulses that only ignite when needed at random times.

However, laser energy per pulse generally decreases with increasing PRF, while laser pulse width increases with increasing PRF, which is especially true for Q-switched, solid-state lasers. While many laser applications require time-shifted laser pulses upon random request, these applications also require that the laser energy and pulse width per pulse remain substantially constant. In the case of link processing on memory or other IC chips, inadequate laser energy will eventually result in incomplete link cutting, while excess laser energy will cause unacceptable damage to the passivation structure or silicon substrate. The acceptable range of laser pulse energy is often referred to as a "process window." For many real IC devices, this process window requires the laser pulse energy to vary by less than 5% from the selected pulse energy value.

Various approaches have been implemented to expand the process window or to supplement the operation within the process window. For example, U.S. Patent No. 5,590,141 to "METHOD AND APPARATUS FOR GENERATING AND EMPLOYING A HIGH DENSITY OF EXCITED IONS IN A LASANT", assigned to the assignee of the present patent application, shows a reduced pulse energy drop as a function of increasing PRF. and a solid-state laser having a high usable PRF. Thus, such lasers can produce more stable pulse energy levels when operated below the maximum PRF.

In addition, U.S. Patent No. 5,265,114 of "SYSTEM AND METHOD FOR SELECTIVELY LASER PROCESSING A TARGET STRUCTURE OF ONE OR MORE MATERIALS OF A MULTILMATERIAL, MULTILAYER DEVICE", assigned to the assignee of this patent application, discloses a link process window, The use of longer laser wavelengths, such as 1,320 nanometers (“nm”), is described to allow wider modification of pulse energy.

U.S. Patent No. 5,226,051 to "LASER PUMP CONTROL FOR OUTPUT POWER STABILIZATION" describes a technique for equalizing laser pulse energy by controlling the electrical current of a pumping diode. This technique works well in practical applications using laser PRFs below about 25KHz or 30KHz.

The laser processing applications described above typically use IR (infrared) lasers with wavelengths of 1,047 nm to 1,324 nm, which work well in PRFs that do not exceed about 25-30 KHz. However, production demands require much higher throughput, so the laser must be able to operate at PRFs much higher than about 25KHz, for example 50KHz to 60KHz or higher. In addition, many laser processing applications are enhanced by using ultraviolet ("UV") energy wavelengths, which are generally less than about 400 nm. This UV wavelength can be generated by subjecting the IR laser to a harmonic generation process that excites a second, third or fourth harmonic of the IR laser. Unfortunately, due to the nature of the harmonic generation, the pulse-to-pulse energy levels of such UV lasers are particularly sensitive to time fluctuations and laser pulse duration in the PRF.

In addition, US Pat. No. 6,172,325 of "LASER PROCESSING POWER OUTPUT STABILIZATION APPARATUS AND METHOD EMPLOYING PROCESSING POSITION FEEDBACK", assigned to the assignee of the present patent application, provides a laser pulse sorting on demand in a random time interval, which is a plurality of laser pulse intervals. Techniques for operating a laser at a constant high repetition rate with a position feedback-controlled laser pulse sorting or gate control device are described. This technique provides good laser pulse energy stability and high throughput.

A typical laser pulse sorting or gate control device is an AOM (Acousto-Optic Modulator) or EOM (Electro-Optic Modulator; also called a Pockel cell). Common EOM materials, such as KD ^* P or KDP, experience relatively strong absorption at UV wavelengths, which in turn results in lower damage boundaries of the material at local heating and used wavelengths along the laser beam path within the device, resulting in half waves of the device. Causes a change in half wave-plate voltage. Another disadvantage of EOM is the questionable ability to perform well at repetition rates above 50KHz.

On the other hand, the AOM material is quite transparent to UV light corresponding to IR light from 250 nm to 2,000 nm, which allows AOM to perform well over the general laser wavelengths in range. In addition, the AOM can easily adjust the desired gate control of the pulse with repetition rates up to several hundred KHz. One disadvantage of AOM is the limited diffraction efficiency of about 75-90 percent.

FIG. 1 shows a typical prior art AOM 10 driven by a Radio Frequency (RF) driver 12 and used for laser pulse sorting or gate control applications, and FIGS. 2A-2D (collectively, 2) shows a corresponding prior art timing graph for the incoming laser pulse 14, the AOM RF pulse 15 and the AOM output pulses 16 and 20. FIG. 2A shows constant repetition rate laser pulses 14a-14k emitted by a laser (not shown) and propagated to AOM 10. FIG. 2B illustrates two examples for applying RF pulse 15 to AOM 10 to select one of laser pulses 14a-14k occurring in the corresponding time period 22a-22k to propagate towards the target. Illustrate the way. In the first scheme, a single RF pulse 15cde (shown in dashed lines) is extended to cover the time intervals 22c-22e corresponding to the laser pulses 14c, 14d and 14e; In the second manner, the separated RF pulses 15c, 15d and 15e are generated to individually cover each time interval 22c 22d and 22e for the laser pulses 14c, 14d and 14e. 2C and 2D show each primary rank beam 20 and zero order rank beams propagating from the AOM 10, as determined by the presence or absence of an RF pulse 15 applied to the AOM 10. Show (16).

1 and 2, the AOM 10 is driven by the RF driver 12. When no RF pulse 15 is applied to the AOM 10, the incoming laser pulse 14 passes substantially through the AOM 10 along its original beam path and generally into the 0th order beam 16. Escape as beam 16 mentioned. When the RF pulse 15 is applied to the AOM 10, some of the energy of the incoming laser pulse 14 is diffracted from the zero order beam 16 to the path of the first order beam 20. The AOM 10 has a diffraction efficiency defined as the ratio of the laser energy in the incoming laser pulse 14 to the laser energy in the primary rank beam 20. Either the primary rank beam 20 or the zero rank rank beam 16 can be used as the operation beam, which depends on different application considerations. For simplicity, the laser pulses 14 entering the AOM 10 are hereinafter referred to as "laser pulses" or "laser outputs", and since they are selected by the AOM 10, the pulses delivered to the target are referred to as "operating laser pulses". Or "operating laser power".

When the primary rank beam 20 is used as the operating beam, the energy of the operating laser pulse can be dynamically controlled down substantially from a maximum of 100 percent, which means that the power of each RF pulse 15 is maximum. This is because it changes from power to zero substantially. Since the AOM's practical limited diffraction efficiency under the maximum allowed RF power load is about 75 to 90 percent, the maximum energy value of the operating laser pulse is about 75 to 90 percent of the energy value at the laser pulse 14. However, when the zero order rank beam 16 is used as the operating beam, the energy of the operating laser pulse can be dynamically controlled from 100 percent of the maximum energy in the laser pulse 14 to 15 to 20 percent of the maximum value. This is because the power of each RF pulse 15 varies substantially from zero to maximum power. For example, in the case of memory link processing, if no operating laser pulses are required, leakage of system laser pulse energy is not allowed, i.e. the operating laser pulse energy must be zero, and thus the primary priority laser beam 20 Is preferably used as the operation beam.

Referring again to FIG. 2, the RF pulse 15 is applied to the AOM 10 in a random integral multiple for the laser pulse interval in this case only if it is a random time interval and an operating laser pulse is required. The random output of the operating laser pulses results in a random variable thermal loading on the AOM 10. The variable thermal load causes geometric distortion and temperature gradients in the AOM 10, which causes gradients in the refractive index of the AOM. The consequences of thermal loading distort the laser beam passing through the AOM 10, which in turn results in degraded laser beam quality and instability in the laser beam path or poor beam position accuracy. This distortion can be corrected to some extent if they remain constant. However, if system laser pulses are required randomly, such as in laser link processing, these distortions will have the same random nature and cannot be substantially corrected.

Test results for AOM devices such as the Model N23080-2-1.06-LTD, made by NEOS technology in Melbourne, Florida, with only 2 watts of RF power, the laser beam pointing accuracy allows RF to be randomly turned on and off to the AOM. If so, it can bias by one milliradian. This deflection is hundreds of times larger than the maximum deflection allowed for a typical memory link processing system. In addition, distortion of the laser beam quality resulting from random thermal loads on the AOM 10 will worsen the focusability of the laser beam, which in turn results in a larger laser beam spot size at focus. For applications such as memory link processing that require the laser beam spot size to be as small as possible, this distortion is not very desirable.

Therefore, what is required is a random selection of operating laser pulses from a high repetition rate laser pulse train without causing distortion of the laser beam and without adversely affecting the positional accuracy caused by random thermal load changes on the AOM. It is an apparatus and a method. Furthermore, what is required is a constant pulse energy and a constant pulse width per pulse on demand and / or on-the-fly (OTF), and different pulse times for various laser applications such as laser link processing on memory chips. A method and apparatus for generating an operating laser pulse having a high accuracy in a section. In addition, what is needed is an efficient and high-throughput apparatus and method for utilizing an operating laser pulse.

It is therefore an object of the present invention to provide an apparatus and method for selecting laser pulses on demand from lasers pulsed at high repetition rates.

The following are some of the advantages of the present invention.

Embodiments of the present invention implement this pulse selection with minimal thermal load variation on the AOM to minimize distortion of the laser beam and position accuracy. These embodiments are system on demand laser pulses having stable pulse energy and stable pulse width at high PRFs for high-accuracy laser processing applications such as selected wavelengths and memory link truncation from UV to near IR. And an apparatus and method for generating the same). Embodiments of the present invention provide an efficient, high throughput apparatus and method using operational laser pulses.

The workpiece processing system of the present invention is characterized in that when the first beam positioning head is directed at the laser beam to process the first workpiece, the second beam positioning head is positioned on the second target or on the next target position on the second workpiece. A laser connected to the beam switching device is used to cause the laser beam or laser pulse to be switched between the first and second beam positioning crystal heads to move to the second set of positions. When the first beam positioning head finishes processing the first workpiece and the second beam positioning head reaches its target position, the beam switching device causes the beam to switch to the second beam positioning head and then the second The beam positioning head directs the laser beam to a target position on the second workpiece, while the first beam positioning head moves to its next target position.

An advantage of the inventive laser beam switching system is that the first and second workpieces receive almost full power of the laser beam for processing. The total use time of the laser beam is increased by a factor of nearly two, depending on the process to travel time ratio. This greatly increases system throughput without having to significantly increase system cost.

Preferred beam switching devices include a first AOM and a second AOM positioned close to each other such that the laser beam (ie, laser pulse) usually passes through the AOM unrefractively and terminates at the beam blocker. When RF energy is applied to the first AOM, about 90 percent of the laser beam is diffracted as the first laser beam and 10 percent remains as a surplus laser beam terminating at the beam blocker. Similarly, when RF energy is applied to the second AOM, about 90 percent of the laser beam is diffracted into the second laser beam and 10 percent remains as a surplus laser beam terminating at the beam blocker. In this embodiment, the laser generating the laser beam moves constantly well at a given pulse repetition rate.

The use of a beam switching device can be advantageous because constant operation of the laser eliminates thermal drift of the laser output. In addition, by operating the first and second AOMs with the pulse selection method of the present invention, thermal load variations of the AOMs will be minimized, thereby increasing the accuracy of laser beam positioning.

Another advantage of using the first and second AOMs as a beam switching device is that these AOMs can act as laser power control devices, which eliminates the need for a separate laser power controller in the processing system of a typical laser based workpiece. . Power control is also possible because the response times of the AOMs are fast enough to program the laser pulse magnitude of the switched laser beam during the processing of the individual target positions relative to the workpiece. Typical laser processing applications result in blind via formation in etched circuit boards, where it is often necessary to reduce the laser pulse energy when the laser beam reaches the bottom of the formed via.

A preferred embodiment of the laser system implements internal cavity beam multiplexing which provides two output beams of polarization state-modulated light emission for use in laser processing applications.

Further aspects and advantages of the invention will be apparent from the following detailed description of the preferred embodiments, which proceeds with reference to the accompanying drawings.

1 is a simplified schematic diagram of a prior art AOM device and RF driver transmitting a zero order rank beam, a primary rank beam or both;

2A-2D are corresponding prior art timing graphs of laser pulses, RF pulses, and first and zero rank AOM output laser pulses, respectively.

3A-3C are corresponding exemplary timing graphs of laser power, RF pulse, and operational laser power, respectively, used in the preferred embodiment.

4A-4C are alternative corresponding exemplary timing graphs of an operating laser output, respectively illustrating the use of an AOM for energy control of the laser output, RF pulse, and operating laser output.

5 is a simplified schematic block diagram of a laser beam switching system of the present invention.

FIG. 6 is a timing diagram of a waveform illustrating an operational timing relationship among the various components of the laser beam switching system of FIG.

7 is a simplified schematic block diagram showing a preferred double AOM laser beam for use with the present invention.

FIG. 8 is a timing diagram of a waveform showing an operative timing relationship between various components of a laser beam switching system using the double AOM switching device of FIG.

9 is a simplified schematic block diagram of a typical workpiece processing system using the laser beam switching device of FIG.

FIG. 10 is a timing diagram of a waveform illustrating an operational timing relationship between various components of the workpiece processing system of FIG. 9.

11A and 11B are simplified block diagrams illustrating a workpiece processing system of the present invention using a common optical processing path for a plurality of laser beams propagating from one and two laser sources, respectively.

12 is a simplified schematic block diagram illustrating an alternative workpiece processing system of the present invention using a high speed EOM and a polarizing beam splitter to implement the laser beam switching device of the present invention.

13 is a block diagram of a simplified illustration showing an alternative laser beam switching system using a high speed steering mirror for switching laser beams along alternate first and second passages.

14 is a laser system configured to implement an internal cavity light beam multiplexing selectively providing two basic wave output beams alternately or simultaneously with polarization state-modulated light emission pulses.

15 is a laser system configured to implement internal cavity light beam multiplexing that simultaneously provides two third-harmonic output beams of polarization state-modulated light emission pulses.

Thermal load changes in AOMs, such as the prior art AOM 10, can be mitigated by using the pulse selection and laser control methods shown with reference to FIGS. 3A-3C and 4A-4C, respectively. 3A-3C (collectively, FIG. 3) are laser outputs 24a-24k (collectively, laser output 24), RF pulses 38a-38k applied to prior art AOM 10. Corresponding timing graphs of (collectively, RF pulses 38) and operational laser outputs 40a, 40c, 40d, 40e and 40i (collectively, operational laser output 40) are shown. In particular, FIG. 3A shows laser power 24a-24k emitted by a laser (not shown) at a constant repetition rate and separated by substantially the same laser power section 41. In a typical embodiment, the laser power repetition rate may be in the range from about 1 KHz to about 500 KHz. Exemplary laser power repetition rates may exist in a range from about 25 KHz to greater than about 100 KHz. For link processing embodiments, each operational laser output 40 preferably includes a single laser pulse having a pulse width of several nanoseconds. However, one of ordinary skill in the art will recognize that each operating laser output 40 may comprise a burst of one or more laser pulses, an example of which is referred to in US Patent No. 6,574,250, assigned to the assignee of this patent application, "LASER SYSTEM." AND METHOD FOR PROCESSING A MEMORY LINK WITH A BURST OF LASER PULSES HAVING ULTRASHORT PULSE WIDTHS ", or alternatively includes bursts of one or more pulses having a pulse width ranging from about 10 picoseconds to about 1,000 picoseconds. can do.

FIG. 3B shows a substantially normal or uniform pulse interval 43a-43j (collectively, an RF pulse interval 43) to maintain thermal load variations on the AOM 10 within a pre-allocated operating error tolerance. Preferred RF pulse selection scheme using RF pulses 38 having a pulse duration equal to 42a and 42b (collectively, RF pulse duration 42) separated by FIG. This tolerance can be a specific thermal load window, but the pre-allocated tolerance can equally or alternatively be spot sized window or beam position accuracy. In one embodiment, the thermal load change is maintained within 5% and / or the beam pointing accuracy is maintained within 0.005 milli radians. In a preferred embodiment, at least one RF pulse 38 is generated to correspond with each laser output 24.

Whenever one of the operating laser outputs 40 is required to affect a target, such as an electrically conductive link, one RF pulse 38 is transmitted through the AOM 10 to request one operating laser. It is applied to the AOM 10 simultaneously with one laser output 24 to be the output 40.

In FIG. 3B, the simultaneous RF pulses 38 become RF pulses 38a, 38c, 38d, 38e and 38i. 3c shows the final corresponding operating laser outputs 40a, 40c, 40d, 40e and 40i. If an operating laser output is not required to correspond with the laser output 24, the RF pulse 38 is applied to the AOM 10 asynchronously with the corresponding pulse of the laser output 24. 3C shows that no working laser output 40 corresponds to the asynchronous RF pulse 38.

Preferably, the asynchronous RF pulse 38 is offset from the start of each laser output 24 by a time offset 44 longer than about 0.5 microseconds. Those skilled in the art will appreciate that while the time offset 44 is shown to follow the laser output 24, the time offset 44 may alternatively set the laser output 24 by a sufficient time to prevent targeting of the laser operation output 40. It will be appreciated that it can be preceded. Thus, the RF pulse interval 43 surrounding one asynchronous RF pulse 38 is shorter than the total average RF pulse interval 43 (e.g., 43c, 43d, 43f, 43g and 43j) (e.g., For example, it may be longer than the RF pulse intervals 43b and 43h, or the average RF interval 43 (for example, RF pulse intervals 43a, 43e and 43i).

Referring again to FIG. 3C, the non-collision sections 46b and 46c between the operating laser outputs 40c and 40d and the operating laser outputs 40d and 40e respectively are generally the same as the laser output section 41. The non-collision sections 46a and 46d between the operating laser outputs 40a and 40c and the operating laser outputs 40e and 40i respectively are approximately integer multiples of the laser output section 41.

Those skilled in the art will preferably note that although the operating laser output 40 is the primary rank beam 20 for all applications, such as link processing, the operating laser output 40 is capable of leaking and has a higher operating laser output power. It will be appreciated that may be the desired zero order rank beam 16.

In a preferred embodiment, the simultaneous and asynchronous RF pulses 38 use the same RF energy, which is the product of the RF power value and the RF duration, as well as the same RF duration and the same RF power value.

4A-4C (collectively, FIG. 4) show that the laser output 24, the RF pulses 38 applied to the AOM 10, and the AOM 10 additionally control the output power of the operating laser output 40. A working laser output 40 is shown that illustrates how it can be used to do so. 4A is the same as FIG. 3A and is shown for convenience only. 4B and 4C show the RF pulse 38 'and the operational laser output 40', along with the corresponding RF pulse 38 and the operational laser output 40, which are shown superimposed in dashed lines for convenience. The energy value of the operating laser output 40 'is attenuated by applying less RF power to the AOM 10 for the RF pulse 38' than for the RF pulse 38; However, the RF pulse duration 42 'is relative to the RF pulse 38' over the RF duration 42 used in the RF pulse 38 to maintain a substantially constant product of the RF power value and the RF duration. As a result, it maintains a substantially constant thermal load on the AOM 10. This technique allows for on-demand selection for a continuum of output power between operating laser outputs 40 or 40 'without substantial variation in thermal load on the AOM 10. Those skilled in the art can maintain the RF duration 42 and RF power values of the asynchronous RF pulses 38 as they are, or can be changed to be within certain tolerances of the RF load change of the coincidence RF pulse 38 '. You will understand.

Preferably, the RF pulse duration 42 ′ is selected from about 1 microsecond to about half of the laser power section 41, more preferably less than 30% of the laser power section 41. For example, if the laser repetition rate is 50KHz and the laser power interval 41 is 20 microseconds, the RF pulse duration 42 'may be anywhere between 1 microsecond and 10 microseconds. The minimum RF pulse duration 42 or 42 ′ is determined by the response time of the AOM 10 and the laser pulse jittering time. It is desirable to disclose the corresponding one of the RF pulses 38 and 38 ′ around the midpoint of the laser output 24. Likewise, the RF pulses 38 and 38 ′ preferably delay or offset about half of the minimum RF duration from the start of the corresponding laser output 24.

The RF power of the RF pulses 38 applied to the AOM 10 can be adjusted to control the energy of the operating laser outputs 40 and 40 'to meet the needs of the target processing, while the RF pulses ( RF pulse durations 42 and 42 'of 38 and 38' may be controlled to maintain a substantially constant RF energy or product of RF power and RF pulses 38 and 38 'duration.

The techniques described above for using AOM in workpiece processing applications solve beam steering accuracy and process window requirements, but do not address the throughput and efficiency issues of workpiece processing. The use of a single laser for workpiece processing is time-efficient because significant time and laser power is wasted while moving the workpiece target position relative to each other. The use of a laser beam for applications such as via formation of an etch-circuit board generally results in the use of only 50% of the laser beam, due to the time required to move the beam between target positions. Beam splitting does not correct this low time utilization problem. Previous workers have been using multiple laser beams to improve throughput, but the extra cost and wasted laser power are still a concern.

The present invention provides an apparatus and method for improving the efficiency and throughput of a single laser workpiece processing system. In the present invention, AOMs using pulse selection techniques are used in combination with laser beam switching or multiplexing techniques to improve workpiece processing and efficiency.

5 and 6 show the laser beam switching system 50 and associated timing aspects of the present invention, in which the laser pulses 54 reflected by the optional folding mirror 56 to the beam switching device 58. ). The beam switching device 58 causes the laser pulse 54 to switch between the first and second beam positioning heads 60 and 62 so that the first beam positioning head 60 causes the laser pulse 54 to be first. If the target location relative to the workpiece 64 is being processed, the second beam positioning head 62 is moving to the target position relative to the second workpiece 66. The laser pulse 54 is directed from the beam switching device 58 to the beam positioning head 62 by an optional collapsible mirror 68. When the first beam positioning head 60 completes the processing of the workpiece 64, an optional shutter (not shown), such as a Q-switch, which turns off the laser 52, as shown in FIG. Laser pulses 54 are dumped to a beam blocker (not shown). When the second beam positioning head 62 reaches its target position, the laser pulse 54 is switched on by this shutter and the second beam positioning head 62 is directed to the workpiece 66. While pointing the laser pulse 54 to the target location, the first beam positioning head 60 moves to its next target position. 6 shows the workpiece processing time as the interval P and the positioner travel time between the target positions as the interval M. FIG.

An advantage of the laser beam switching system 50 is that the first and second workpieces 64 and 66 alternately receive almost full power of the laser pulses 54 for processing. The total use time of the laser pulses 54 is increased by almost two factors, which depends on the process to travel time ratio. This greatly increases system throughput without having to significantly increase system cost.

7 and 8 show a preferred beamswitching device 70 and associated timing relationship diagrams. Since the beam switching device 70 will include first and second AOMs 72 and 74 positioned in optical series, the laser beam or laser pulse 76 will usually reflect the AOMs 72 and 74 without reflection. It passes through and ends as a laser beam 76A relative to the beam blocker 78. However, when the first RF driver 80 applies an about 6 watt 85 MHz RF signal to the first AOM 72, about 90% of the laser beam 76 is diffracted as the laser beam 76B, 10 % Will remain as laser beam 76A. Similarly, when the second RF driver 82 applies about 6 Watts of 85 MHz RF signal to the second AOM 74, about 90% of the laser beam 76 is diffracted as the laser beam 76C and 10% Remains as the laser beam 76A. In this embodiment, the laser beam 76 generating the laser is constantly moving at the desired pulse repetition rate.

When using the beam switching device 70, when no shutter or Q-switch is switched between the laser beams 76B and 76C, it is not necessary if a time interval is required, which means that the first and second AOM ( It is necessary to shield the RF signal applied to both 72 and 74, thereby directing all laser beams 76 to beam blocker 78.

Beam switching device 70 may be advantageous because constant operation of the laser eliminates thermal drift of the laser output. Moreover, by operating the AOMs 72 and 74 with the pulse selection method described with reference to FIGS. 3 and 4, thermal load variations will be minimized, thereby increasing the laser beam positioning accuracy. Each of the first and second AOMs 72 and 74 is preferably model N30085 manufactured by NEOS Technology Inc., Melbourne, Florida. The N30085 AOM has a specified 90% diffraction efficiency when driven at 2 watts of 85 MHz RF power.

Another advantage of the beam switching device 70 is that it can act as a laser power control device, eliminating the need for a separate laser power controller in a typical laser based workpiece processing system. Power control is also possible because the response times of the AOMs 72 and 74 are fast enough to program the laser pulse magnitudes of the laser beams 76B and 76C during the processing of a single target site in the workpiece. Typical laser processing applications are blind via shapes in visual-circuit boards, where it is often necessary to reduce the laser pulse energy when the laser beam reaches the bottom of the formed vias.

9 and 10 show a general workpiece processing system 90 and associated operational tie relationship diagrams, each using a beam switching device 70. The laser 92 and the variable beam expander 94 cooperate to produce a laser beam 76 that propagates through the beam switching device 70, which beam switching device 70 is described with reference to FIGS. 7 and 8. And operate to produce laser beams 76A, 76B and 76C. The laser beam 76A ends at the beam blocker 78. The laser beam 76B is reflected by the optional collapsible mirror 96 and directed by the first XY scanner 98 to the target locations 1, 2, 3 and 4 relative to the first workpiece 100. Equally, the laser beam 76C is reflected by the optional collapsible mirror 102 and directed by the XY scanner 104 to the target locations 1, 2, 3 and 4 with respect to the second workpiece 106. do. The first and second XY scanners 98 and 104 are mounted on the first and second X positioning stages 108 and 110, respectively, and the first and second workpieces 100 and 106 are Y positioning stages. It is mounted on 112. Those skilled in the art will appreciate that the scanner and workpiece are mounted on a positioner system configured with separate axes, but planar and stacked configurations may alternatively be used. In addition, those skilled in the art will appreciate that the target sites for the first and second workpieces may be on a common substrate and / or may not share corresponding target sites.

FIG. 10 shows a laser beam 76B for processing (drilling) the target location 1 relative to the workpiece 100, while the second XY scanner 104 determines the position of the laser beam 76C. Moving to target location 1 on 106. When the laser beam 76C is processing the target location 1 with respect to the workpiece 106, the first XY scanner 98 sets the position of the laser beam 76B with the target location with respect to the workpiece 100. Moving to (2). This process continues with respect to the target locations 2, 3 and 4 to complete the processing of the target location 4 relative to the workpiece 106, at which time the first and second X positioning stages 108 and 110 and Y positioning stage 112 are used to position the first and second XY scanners 98 and 104 relative to the target locations 5, 6, 7, and 8 of the respective workpieces 100 and 106. Run the move. The X and Y linear positioning stages work in constant motion in cooperation with the XY scanner. Positioning systems suitable for use with the present invention are described in "HIGH SPEED, HIGH ACCURACY MULTI-STAGE TOOL POSITIONING SYSTEM" of US Pat. No. 5,751,585 assigned to the assignee of this patent application.

FIG. 11A shows the workpiece processing system 120 of the present invention using a common module imaging optical assembly 122 and a variable beam expander 94 for optically processing both laser beams 76B and 76C. In this embodiment, the laser 92 and optional fixed beam expander 124 cooperate to produce a laser beam 76 propagating through the beam switching device 70, which is shown in FIG. 7. And operate as described with reference to 8 to generate laser beams 76A, 76B and 76C. Laser beams 76B and 76C propagate along separate propagation path portions. The first turning mirror 126 allows the laser beam 76B to pass through a half-wave plate 128, and the half-wave plate 128 converts the polarization state of the laser beam 76B into a laser beam ( It changes to 90 degrees with respect to the polarization state of 76C). This 90 degree phase-converted laser beam 76B is directed to the polarizing beam combiner 132 by the second turning mirror 130. The laser beam 76C is directed to the polarization beam combiner 132 by a third turning mirror 134, which combines the separate path portions through which the laser beams 76B and 76C propagate into a common propagation path. . The laser beams 76B and 76C merge into a common laser beam 76D, which passes through an imaging optical assembly 122 and an optional variable expander 94 and propagates along a common path portion to polarize beam splitters. Propagated to 136. The second polarization beam splitter 136 splits the common laser beam 76D into laser beams 76B and 76C. The laser beam 76B is directed by the fourth turning mirror 138, for example to the first XY scanner 98; The laser beam 76C is directed to the second XY scanner 104, for example.

Beam expander 124 shapes the laser beams 76B and 76C in the form of a Gaussian spatial distribution of light energy. Imaging optical assembly 122 shapes the Gaussian spatial distributions of lasers 76B and 76C to form an output beam of uniform spatial distribution for delivery to XY scanners 98 and 104. Preferred imaging optical assemblies are of the diffractive beam shaper type as described in US Pat. No. 5,864,430.

11B shows an alternative workpiece processing system 120 ′ in which the beam switching device 70 is removed and the laser beams 76B and 76C propagate from separate laser sources 92b and 92c, respectively. do. The size of the laser beam 76B is determined by the beam expander 124b, and the size of the laser beam 76C is determined by the beam expander 124c. The use of separate laser sources 92b and 92c aids in the construction of optical components in which one or more turning mirrors 126, 130 and 134 can be removed, as shown in FIG. 11B.

Each of the workpiece processing systems 120 and 120 'may be advantageous because only one expensive set of beam imaging optics is required. Moreover, in the case of the workpiece processing system 120, the use of the beam switching device 70 allows implementation with smaller optical components, which means that the switching is smaller than that found in downstream switching components. Because it is accomplished by breadth.

12 illustrates another alternative of the present invention using a fast EOM 142 and a polarizing beam splitter 144 to implement switching of the laser beam 146 between the first and second XY beam scanning heads 98 and 104. Shows a typical workpiece processing system 140. In the workpiece processing system 140, the laser 92 emits a laser beam 146, which is transmitted and propagated and optically processed by the optical module 148 and the laser power controller 150. . The laser beam 146 exits the laser power controller 150 and enters the high speed EOM 142, which in turn polarizes the laser beam 146 into non-rotating-polarized and rotating-polarized laser beams 146U and 146R, respectively. do. The polarizing beam splitter 144 receives the non-rotating laser beam 146U and directs it to the first XY scanning head 98 according to the turning mirror 152. The polarization beam splitter 144 receives the rotated laser beam 146R and directs it to the second XY scanning head 104.

A disadvantage of the workpiece processing system 140 is that current actual EOMs are limited in laser pulse repetition rate and cannot withstand high amounts of ultraviolet laser beam power. Another vulnerability is that dumping of the unnecessary laser beam energy requires shutting off or turning off the laser 92, such as with a Q-switch located inside the cavity of the laser 92.

The workpiece processing system 140, on the other hand, is advantageous, which is simpler than the double AOM beam switching diabis 70 described with reference to FIG. 7 and collides with the target site as the laser beams 146U and 146R. This is because the laser beam 146 has a high extinguishing ratio that allows substantially all the power.

FIG. 13 shows a laser that emits a laser beam 214 deflected by a fast steering mirror (“FSM”) along the first and second paths 218 and 220 that the laser 212 alternates. An alternative embodiment of the beam switching system 210 is shown. The FSM 216 preferably uses a mirror having a deflection angle controlled by a material that converts the voltage into angular displacement. FSM 216 operates similarly to galvanometer driven rotating mirrors, but at angular speeds up to 10 times faster than galvanometers and at angular speeds over each deflection range 222 up to about 5 milli radians. Deflecting a general laser beam diameter having this limited angular deflection range is preferably about long enough to separate the first and second beam paths 218 and 220 by a sufficient distance 226 of about 10 millimeters. It will require a path length 224 equal to 1 meter, which is the first and second beam paths for reflection by the first and second turning mirrors 230 and 232, respectively. By separating the 218 and 220 further and inserting an HR coated right angle prism 228 between these paths that is directed to the associated laser beam scanning head (not shown). As with any previous beam expander, where the diameter is the smallest, the switching laser beam 214 is necessary to sufficiently separate the first and second paths 218 and 220 reflected by the rectangular prism 228. Length 224 will be minimized.

The FSM 216 may be a two-axis device that may further provide for switching the laser beam 214 to three or more positions. For example, the laser beam 214 may be directed to the beam blocker during long-distance travel as described with reference to FIGS. 9 and 10, thus maintaining a constant thermal condition in the laser 21 and related to the laser beam power stability Minimize the problem.

If the travel time is 3 ms or more and the workpiece processing time and the laser beam switching time are less than 1.0 ms, the laser beam switching system 210 is a two laser system and has a single laser workpiece processing process having the same workpiece processing throughput. Allow implementation of the system.

The laser beam switching system 210 is advantageous because the use of a single laser and associated optics is reduced by 20% to 40%, depending on the type of laser required, as compared to the two laser systems.

FIG. 14 shows a laser system 300 that is configured to implement internal cavity light beam multiplexing that selectively or alternatively provides two output beams of polarization state modulated light emission pulses. The laser system 300 provides a gain, i.e. a laser resonator 302, in which a laser laminating medium 304 is located along the beam path 306 between the Q-switch 308 and the variable optical retarder 310. Include. Pumping source 312 optically connected with laser light emitting medium 304 provides light pumping to simulate the laser light emitting gain of laser light emitting medium 304. Diode lasers are the preferred pumping source 312. The beam steering mirrors 322 and 324 guide the propagation direction of the laser beam formed in the laser resonator 302 along the portion of the beam path 306 between the laser resonator 302 and the variable optical retarder 310. The optical polarization beam splitter 302 is located at the output 328 of the variable optical retarder 310. The laser resonator 326 effectively establishes two laser cavities, the first of which is the internal cavity dichroic mirror surface 332 and rear mirror 330 of the first output coupler 334 through which the first output beam is propagated. The second of which is defined by the internal cavity dichroic mirror surface 336 and rear mirror 330 of the second output coupler 338 through which the second output beam is propagated. Dichroic mirror surfaces 332 and 336 receive incident light propagating from their respective outputs 340 and 342 of optical polarization beam splitter 326. Both output beams are the fundamental wavelengths established by the laser lasing medium 304.

The Q-switch 308 changes the Q value of the laser resonator 302 in response to the applied Q-switch drive signal 344 by selectively generating the high and low Q states of the laser resonator 302. The high Q state results in the generation of a plurality of time-displaced light pulses, and the low Q state results in the generation of redundant or very low intensity light pulses.

The laser system 300 is configured to maintain oscillation in the laser resonator 302 even when the output beam is extracted from the laser cavity. If the laser light emitting medium 304 is of an isotropic type such as Nd: YAG, the oscillation of the laser resonator 302 is maintained even if the variable optical retarder 310 changes the polarization state by 90 degrees. . If the laser light emitting medium 304 is of anisotropic type such as YLF or YV0 ₄ (vanadate), the gain of the two orthogonal polarization states are different, thereby jeopardizing the maintenance of stable oscillation. In order to operate with the anisotropic laser light emitting medium, the same type of second laser light emitting medium 304a (shown by dashed dashed line) is introduced into the laser resonator 302 in the direction orthogonal to the laser light emitting medium 304, so that the two The orthogonal polarization state does not affect the cavity gain.

Operation of the variable optical retarder 310 determines the generation of the first and second output beams propagating from the output couplers 334 and 338. Whenever the drive signal 346 applied to the variable optical retarder 310 causes this beam to divide the quarter wave delay with respect to the incident light, the circularly polarized light propagating from the output 328 is the polarization beam splitter 326. ) To dichroic mirror surfaces 332 and 336 and then simultaneously exit from output couplers 334 and 338 as separate beam components of the fundamental wavelength. Each time the drive signal 346 applied to the variable optical retarder 310 causes this beam to divide the zero and half wave delays (or similar plurality of half wave delays) alternately with respect to the incident light, The linearly polarized beam propagating from the output 328 is directed by the polarizing beam splitter 326 to the dichroic mirror surfaces 332 and 336 and then alternately exits from the output coupler 334 and 338. The various states of the drive signal 346 described above are applied to the laser resonator regardless of whether the laser resonator 302 includes the uniform type laser emitting medium 304 or the anisotropic type laser emitting medium 304 and 304a. Applicable. The drive signal 346 represents information derived from a tool path file present in the processing system and is transmitted to the variable optical retarder 310 as a pulsed waveform by a pulse generator (not shown). .

There are different coupling losses in the laser resonator 302 depending on whether the fundamental wave deviates from both or one side of the output couplers 334 and 338. If the combined value is too large and the fundamental wave leaves both output couplers 334 and 338 simultaneously, the laser resonator 302 will not generate an oscillation. Therefore, the proper choice of connection value is an important factor contributing to the sustained oscillation.

Those skilled in the art, at the output of output couplers 334 and 338, the placement of nonlinear crystals that function as second harmonic generators, third harmonic generators, or both, produce an ultraviolet light beam (infrared fundamental wave) at alternating or simultaneous switching capacity. Will understand.

FIG. 15 shows a laser system 400 configured to implement internal cavity optical multiplexing simultaneously providing two third harmonic light output beams of light emitting pulses modulated with polarization. The laser system 400 includes a harmonic frequency generation and fixed optical delay device with added laser resonator of the laser system 400, a beam dump dichroic mirror as a replacement for beam steering mirrors 322 and 324, and an output coupler 334 and It differs from laser system 300 in that it includes the differently characterized dichroic surface of 338. The components of the laser system 400 corresponding to the components of the laser system 300 are identified by the same reference symbol according to the prime sign '.

The laser resonator 302 'effectively establishes two laser cavities, the first of which is defined by the dichroic mirror surface 332' and the rear mirror 330 'of the first output coupler 334'. The second is defined by the dichroic mirror surface 336 'and the rear mirror 330' of the second output coupler 338 '. Mirror surfaces 332 'and 336' reflect the wavelength corresponding to the fundamental frequency and then transmit a wavelength corresponding to the third harmonic of the fundamental frequency established by laser light emitting medium 304 '. The laser resonator 302 'includes an optical retardation device, that is, a waveplate 402', a nonlinear crystal functioning as the third harmonic generator 404, and a nonlinear crystal functioning as the second harmonic generator 406. All of which are placed between the variable optical retarder 310 ′ and the beam dump dichroic pair mirror 408. Each member of the beam dump dichroic pair mirror 408 transmits light at the second and third harmonic frequencies and maintains the gain value of the laser resonator 302 'at approximately 1 μm (IR) wavelength corresponding to the fundamental frequency. Reflects light at a frequency, at which the Q-switch 308 'and the laser emitting medium 304' operate.

In cooperation with the waveplate 402 and harmonic generators 404 and 406, the operation of the variable optical retarder 310 'is propagated from the output coupler 334' and 338 'as a third (UV) component that propagates as two separate beam components. ) Determine the generation of the harmonic beam and the return of the fundamental (IR) beam to the laser emitting medium 304 'to maintain the fundamental beam oscillating in the laser resonator 302'. In the embodiment of FIG. 15, the third harmonic generator 404 and the second harmonic generator 406 are made of LBO crystals, which are cut differently for each of the second and third harmonic generation processes. For the Type-I process for the second harmonic generator 406, the laser beam leaving the second harmonic generator 406 becomes fundamental and second harmonics having an orthogonal polarization state. The laser beam that exits the second harmonic generator 406 and enters the third harmonic generator 404 exits the third harmonic generator as the fundamental and third harmonics having a non-uniformly oriented polarization state.

In order to achieve the return of the fundamental wave to the laser emitting medium 304 'and thereby to maintain the fundamental wave oscillation in the laser resonator 302', the wavelength plate 402 is itself properly set with an optical axis, It becomes the type which delays the fundamental wave by 1/4 wavelength and the 3rd harmonic by one wavelength with respect to each pass. Therefore, the wave plate 402 divides the circularly polarized light into fundamental waves propagating from the wave plate 402 toward the beam separator 326 'and does not affect the polarization state of the third harmonic. The operation of the variable optical retarder 310 'determines the generation of the first and second output beams propagating from the output couplers 334' and 338 '. The application of the drive signal 346 'to the variable optical retarder 310' nominally dividing the quarter wavelength delay of the fundamental wave and the three quarter wavelength delay of the third harmonic is on the wavelength plate 402. The circularly polarized fundamental wave is converted into a linearly polarized wave rotated by 90 degrees with respect to the original linearly polarized state established prior to the incidence of the fundamental wave. The linearly polarized fundamental wave propagating from the variable optical retarder 310 'is incident on one of the dichroic surfaces 332' and 336 'depending on the direction of the polarizing beam splitter 326' and then the variable optical delay Propagation back to the ruler 310 '. The return path through the variable optical retarder 310 'converts the linearly polarized fundamental wave into a circularly polarized fundamental wave, and then the reflection path through the wavelength plate 402 converts the circularly polarized fundamental wave. It converts the linearly polarized fundamental wave toward the same direction as the original fundamental wave. The linearly polarized fundamental wave is then returned to the laser emitting medium 304 'for further oscillation. The distance between the polarizing beam splitter 326 'and the respective output coupler 334' and 338 'is such that the polarization state of the return beam is essentially combined to form a fully circularly polarized beam.

In order to achieve propagation of two separate third harmonic beam components through the output coupler 334 'and 338', the third harmonic at the first incidence to the variable optical retarder 310 'is circularly polarized. While the fundamental wave experiences a quarter-wave delay. A circularly polarized third harmonic is incident on the polarization beam splitter 326 ', which splits the third harmonic into two circularly polarized beam components, each of which is a dichroic surface 332' and Propagates through the other of 336 'and exits each one of the output couplers 334' and 338 '. Therefore, this polarization state relationship means that the third harmonic beam component circularly polarized such that the polarization beam splitter 326 'directs the linearly polarized primary beam to one of the dichroic surfaces 332' and 336 'is a dichroic surface. To one of 332 'and 336'. The dichroic surface 332 'reflects the primary beam back into the laser light emitting medium 304' for further amplification, after which the dichroic surfaces 332 'and 336' are directed to the respective output coupler 334 'and 338'. Through the circularly polarized third harmonic beam component is transmitted.

Those skilled in the art will appreciate that removing the wavelength plate 402 and applying a drive signal 346 'that alternates the zero and one-half wavelength delays for the fundamental wave to the variable optical retarder 310' alternately output coupler 334 '. And 338 '), will alternately provide propagation of the third harmonic.

In the laser systems 300 and 400, the laser light emitting media 304 and 304 'are preferably one of Nd: YAG, Nd: YVO ₄ , or Yb (Ytterbium) ytterbium fiber lasers. The fiber laser may be a Master Oscillator Power Amplifier (MOPA) type and / or a Q-switch. Q-switches 308 and 308 'are preferably acoustic-light modulators. Q-switches that support two orthogonally oriented laser light emitting media are commercially available. The variable optical retarders 310 and 310 'can be BBO or KD ^* P crystals, the latter examples of which are electronic optical switching modules manufactured by both companies of LINOS Photonics Co., Ltd. & KG Co., Germany. It is a LINOS RTP-Pockels cell (355 nm) driven by RVD.

Those skilled in the art will appreciate that the third and second harmonic generators 404 and 406, which generate a 355 nm third harmonic beam in the laser system 400, have only one implementation to achieve harmonic beam generation in the laser resonator 302 '. It will be understood that it indicates.

Those skilled in the art will recognize that portions of the invention may be implemented differently from the embodiments described above for the preferred embodiment. For example, galvanometers and rotating mirror devices can also be used as laser beam switching devices; IR, visible and UV lasers can be used; The target location can be placed in a single or a plurality of workpieces; Laser beam switching can be performed for three or four or more beam paths; Multiple lasers can be used and each of these laser outputs can be switched between multiple paths; And the scanning head used may further include techniques other than galvanometers, FMSs, and XY coordinate positioning techniques.

It will be apparent to those skilled in the art that many other changes can be made in the details of the above-described embodiments without departing from the main principles of the invention. Accordingly, the scope of the invention should only be determined by the claims which follow.

As mentioned above, the present invention relates to a laser, in particular to increase workpiece processing by alternately switching a single laser beam in two or more beam paths so that one of the beam paths is used to machine one workpiece. Different beam paths, on the other hand, are directed to methods and apparatus which are positioned for the processing of other workpieces.

Claims (31)

A system configured to selectively direct a laser beam in a plurality of beam propagation directions in a coordinated manner to achieve high speed processing of materials in different regions of a target sample, the system comprising: A laser source for emitting a laser beam comprising a series of laser pulses; A beam switching device for receiving a series of laser pulses, the beam switching device directing, in response to a beam switching signal, first and second groups of laser beam pulses to propagate along first and second beam axes; A first control signal for selectively positioning a first beam axis in another first target area of the target sample and providing relative movement of the first beam axis and the target sample to process material in the first target area of the target sample; A first positioning mechanism responsive to; A second control signal for selectively positioning a second beam axis in another second target area of the target sample and providing a relative motion of the second beam axis and the target sample to process material in the second target area of the target sample. A second positioning mechanism responsive to; A controller for generating a beam switching signal and the first and second control signals to perform coordinated system operations in first and second operating sequences, The first sequence of operations includes a beam switching device for directing a first group of laser beam pulses for incidence into a selected one of the first target regions, wherein the first positioning mechanism is configured to cause the first group of laser pulses to be selected. Provide relative motion to enable processing of material in the first target area, and during the material processing by the first group of laser pulses, the second positioning mechanism is selected from one of the second target areas. Provide relative motion to position the second beam axis at; The second sequence of operations includes a beam switching device for directing a second group of laser beam pulses for incidence onto the selected second target area, the second positioning mechanism wherein the second group of laser pulses is selected from the selected first target area. Provide relative motion to enable processing of the material in the second target area, and during the material processing by the second group of laser pulses, the first positioning mechanism is configured to select the first from the selected first target area. And selectively direct the laser beam in a plurality of beam propagation directions to provide relative motion to position the first beam axis into the next selected one of the target regions. A beam switching device that receives a laser beam and provides a beam output that selectively propagates along another beam axis, the device comprising: A controller for generating control drive signals in the first and second states; First and second optically coupled acoustic-light modulators, wherein the first acoustic-light modulator receives an incoming laser beam, wherein the first and second acoustic-light modulators are the first and second of the control device signal. An acoustic-light modulator, wherein the acoustic-light modulator produces respective first and second laser beam outputs propagating from the second acoustic-light modulator by cooperating in response to a condition; The first laser beam output includes a major component that propagates along a first beam axis and a subcomponent that propagates along a first minor component axis, wherein the second laser output is angularly from the first beam axis. And a subcomponent propagating along a second beam axis that is offset and a subcomponent propagating along a second subcomponent axis substantially coincident with the first subcomponent axis. The method of claim 2, And a beam blocker positioned to terminate the subcomponents propagating along the first and second subcomponent axes. The method of claim 2, The controller operatively includes first and second RF drivers coupled with respective first and second acoustic-optic modulators; And In a first state of the control drive signal, the first RF driver causes the first acoustic-light modulator to pass an incoming laser beam as an unbiased beam incident on the second acoustic-light modulator, and And a second RF driver to selectively cause diffraction of the incident unbiased beam to form a subcomponent through which the second acoustic-light modulator propagates along the first subcomponent axis and a principal component propagating along the first beam axis. A beam switching device providing a propagating beam output. The method of claim 2, The controller operatively includes first and second RF drivers coupled with respective first and second acoustic-optic modulators; And In a second state of the control drive signal, the second RF driver causes the second acoustic-light modulator to pass incoming light as an unbiased beam, and the first RF driver directs the first acoustic-light modulator. Providing a selectively propagating beam output, causing the diffraction of an incoming laser beam to form a subcomponent propagating along the second subcomponent axis and a principal component propagating along the second beam axis. The method of claim 2, Wherein said first and second optically coupled acoustic-light modulators are positioned in optical series to provide selectively propagating beam output. A low cost compact laser beam switching system, the system comprising: First and second laser beam components propagating along respective first and second propagation path portions, each of the first and second laser beam components characterized by a state of optical characteristic; 2 laser beam components; Cooperate to divide the relative change in optical property states of the first and second laser beam components and to combine the first and second propagation path portions into a common propagation path portion through which the first and second laser beam components propagate. A set of one or more optical components;   An imaging optical assembly positioned along a common propagation path to form beam-shaped first and second laser beam components and shaping a spatial distribution of light energy of the first and second laser beam components; And This component is adapted to each state of optical properties for receiving the beam-shaped first and second laser beam components propagating along the common propagation path portion and for propagating along separate first and second output path portions. Oriented beam separator Including, low cost compact laser beam switching system. The method of claim 7, wherein And wherein the optical characteristic is phase and the relative change in state of the characteristic is a change in phase displacement between the first and second beam components. The method of claim 7, wherein The set of one or more optical components includes a phase-change device positioned in first and second propagation path portions and a polarization beam combiner positioned to couple the first and second propagation path portions into the common propagation path portion. Low cost compact laser beam switching system. The method of claim 9, The phase-change device comprises a half-wave plate. The method of claim 7, wherein The beam switching device, in response to a control signal, two optically coupled acoustic-lights that selectively provide first and second laser beam components that sequentially propagate along each of the first and second propagation path portions. A low cost compact laser beam switching system comprising a modulator. The method of claim 11, Wherein said two optically coupled acoustic-light modulators are positioned in optical series. The method of claim 7, wherein And the beam splitter comprises a polarizing beam splitter for guiding the beam-shaped first and second laser beam components in accordance with a polarization state. The method of claim 7, wherein The spatial distribution shaping of light energy by the imaging optical assembly results in a uniform spatial distribution. The method of claim 7, wherein The imaging optical assembly and the polarizing beam splitter along the common propagation path portion to determine beam diameters of the beam-shaped first and second laser beam components propagating along the separate first and second output path portions. And a beam expander positioned between the low cost compact laser beam switching system. The method of claim 15, And the beam expander is of variable beam extension type. The method of claim 7, wherein And a first and second positioning mechanism optically associated with said respective beam-shaped first and second laser beam components. The method of claim 7, wherein And at least one beam expander optically associated with the first and second laser beam components to establish for injecting a light beam of desired light energy spatial distribution and diameter onto the imaging optical assembly. The method of claim 18, And wherein the desired light energy spatial distribution is of a Gaussian shape. The method of claim 18, And the first and second laser beam components propagate from separate light sources that are optically coupled to other beam expanders. The method of claim 18, Wherein the first and second laser beam components are derived from an output beam emitted by one laser source and propagating through one beam expander. The method of claim 7, wherein A beam switching device that receives an incident laser beam and optionally guides the laser beam to sequentially shape the first and second laser components propagating along the first and second propagation path portions in response to a control signal. Further comprising, a low cost compact laser beam switching system. The method of claim 22, A low cost compact, further comprising a beam expander positioned to receive a laser beam prior to incidence on the beam switching device to establish incidence on the imaging optical assembly with the first and second beam components of a desired optical energy spatial distribution and diameter. Laser beam switching system. The method of claim 23, And wherein the desired optical energy spatial distribution is Gaussian shaped. A laser consisting of a plurality of output couplers to produce a plurality of output beams, the laser comprising: A pumping source optically connected with a laser emitting medium present in the laser resonator characterized by a Q value, the pumping source providing pumped light to simulate a laser emission gain of the laser emitting medium; A Q-switch located within the resonator and operative to change the Q value of the laser resonator in response to a Q-switch drive signal that selectively generates high and low Q states of the laser resonator, the high and low Q The state comprises a Q-switch, producing a beam of a plurality of time-shifted light emitting pulses characterized by the light polarization state; A variable optical retarder located within the laser resonator and responsive to an optical retarder drive signal for imparting a selected amount of optical delay to a beam of light emitting pulses, wherein the selected amount of optical delay divided by the variable optical retarder is A variable optical retarder for selectively changing the light polarization state of the beam of light emission pulses to produce a polarization state-modulated light emission pulse; And A polarization sensitive beam that accepts a polarization state-modulated light emitting pulse and cooperates to guide the pulse through the first and second output couplers in accordance with a selected amount of delay divided by the variable optical retarder into the light emitting pulse Separator and first and second internal intercavity light receiving surface A laser comprising a plurality of output couplers, including. The method of claim 25, Wherein the drive signal causes the variable optical retarder to divide the half wavelength difference for the selected amount of optical delay. The method of claim 26, Wherein one of said selected amounts of optical delay exhibits a plurality of quarter wavelengths, and wherein said polarization state-modulated light emitting pulses propagate simultaneously through first and second output couplers. The method of claim 26, One of the selected amounts of optical delay represents a plurality of quarter wavelengths, and wherein the polarization state-modulated light emitting pulses propagate at one time through one or the other of the first and second output couplers. Laser with output coupler. The method of claim 25, The beam of the plurality of time-shifted light emitting pulses constitutes a first beam, The laser further includes first and second harmonic wavelength generators, and an optical retardation device, wherein the optical retardation device comprises a second beam of a plurality of time-shifted light emitting pulses characterized by a polarization state and the first Optically connected to the laser emitting medium and positioned within the laser resonator to produce a beam, the first and second beams having a harmonic associated wavelength; The first and second output couplers comprise respective first and second dichroic mirrors transmitting another one reflecting one of the first and second light beams; The optical delay device is defined as a delay value; And The selected amount of optical delay and the predetermined delay value cause one of the first and second beams to reflect off from one of the first and second output couplers in each of the first and second forward polarization states, And a plurality of output couplers cooperating to cause another of the first and second beams to pass through the other of the first and second output couplers in a first and second pure optical polarization state. The method of claim 29, A plurality of output couplers, further comprising third and fourth dichroic mirrors positioned in the laser cavity and configured to reflect light of the reflected one of the first and second light beams for amplification by the laser emitting medium Consisting of a laser. The method of claim 25, The beam of the plurality of time-shifted light emitting pulses constitutes a first beam, The laser further includes first and second harmonic wavelength generators, and an optical retardation device, wherein the optical retardation device comprises a second beam of a plurality of time-shifted light emitting pulses characterized by a polarization state and the first Optically connected to the laser emitting medium and positioned within the laser resonator to produce a beam, the first and second beams having a harmonic associated wavelength; The first and second output couplers include respective first and second dichroic mirrors transmitting the other one reflecting one of the first and second light beams; The first and second output couplers each of the first and second dichroic mirrors reflecting one and transmitting the other one of the first and second light beams; The optical delay device is defined as a delay value; And The selected amount of optical delay and the predetermined delay value cause one of the first and second beams to reflect from one of the first and second output couplers in each of the first and second forward polarization states, each first And cooperating to cause another of the first and second beams to pass through one of the first and second output couplers in a second pure optical polarization state.

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