KR101389515B1 - Optical system for correcting a distortion of ultrashort laser pulse - Google Patents

Abstract

The present invention relates to a microwave oven comprising a first prism provided at a position where an ultrasonic laser pulse is incident, a second prism provided in a straight line direction of the ultrasonic laser pulse passing through the first prism, And a fourth prism provided in a straight line direction of the microwave pulse having passed through the third prism, wherein a first distance between the first prism and the second prism, a third distance between the third prism and the third prism, And a second distance between the fourth prisms is made different to compensate for the spatial chirp.

Description

TECHNICAL FIELD [0001] The present invention relates to an optical system for correcting distortion of an ultra-violet laser pulse,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to distortion compensation of an ultrashort laser pulse, and more particularly, to an optical system for compensating a spatial chirp generated in an ultrashort laser pulse such as a femtosecond laser pulse.

Currently, micromachining technology using laser is widely used as an essential technology for processing high-quality parts in high-tech industries such as semiconductors, electronics, automobiles, and mechatronics.

In light of recent trends in lightweight, thin, dense and highly integrated industries, laser machining has become possible with more advanced microfabrication using advanced microwave lasers such as femtosecond lasers. For example, the femtosecond laser has a very short pulse width and is capable of non-thermal processing. Moreover, the peak power is very large, so that the power density of the focusing surface can be made very high.

However, when pulsed laser pulses, such as femtosecond laser pulses irradiated for processing such as non-thermal processing, pass through various optical systems, distortions such as spatial chirp are inevitably generated. Such distortions cause undesired characteristics It causes. That is, the microwave pulse having the distorted microwave has an adverse effect on micromachining.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical system for distortion compensation of a microwave laser pulse, which is capable of processing a high quality part by correcting the spatial chirp of the microwave laser pulse.

According to another aspect of the present invention, there is provided an optical system for compensating distortion of an ultra-violet laser pulse. The optical system for compensating for the distortion of the microwave laser pulse includes a first prism provided at a position where the microwave laser pulse is incident, a second prism provided in the straight direction of the microwave pulse passed through the first prism, And a fourth prism provided in a straight line direction of the microwave laser pulse passing through the third prism, wherein the third prism is disposed in a straight line direction of the passed microwave laser pulse, 1 distance between the third prism and the fourth prism.

An optical system for compensating for the distortion of the microwave laser pulse includes a first distance adjuster positioned between the first prism and the second prism to adjust the first distance and a second distance adjuster between the third prism and the fourth prism And a second distance adjuster for adjusting the second distance.

The first distance adjuster includes first and fourth reflection mirrors provided on the laser pulse path of the first prism and the second prism, and first and second reflection mirrors provided on the first and second movable stages, And the microwave pulse having passed through the first prism forms a pulse path in the order of the first reflection mirror, the second reflection mirror, the third reflection mirror, and the fourth reflection mirror.

The second distance adjustment unit includes fifth and eighth reflection mirrors provided on the laser pulse path of the third prism and the fourth prism, and second and seventh reflection mirrors provided on the second movement stage and the sixth and seventh reflection mirrors And the microwave pulse having passed through the third prism forms a pulse path in the order of the fifth reflection mirror, the sixth reflection mirror, the seventh reflection mirror, and the eighth reflection mirror.

In the above, the first distance and the second distance are at least 20 mm and at most 250 mm, and the third distance between the second prism and the third prism is at least 10 mm and at most 250 mm.

According to another aspect of the present invention, there is provided an optical system for compensating distortion of an ultra-violet laser pulse. The optical system for compensating for the distortion of the microwave laser pulse includes a distortion compensating optical system for passing an incident microwave laser pulse in the order of a first prism, a second prism, a third prism and a fourth prism in order, And a second multiplexer for dividing the first and second superfrequency laser pulses into first and second superfine laser pulses, and a second multiplexer for receiving the second superfine laser pulses to analyze the degree of distortion, And a position correcting unit for performing at least one of a first distance between the first and second prisms and a second distance between the third and fourth prisms by the distortion compensation operation, Performs a position correcting operation to make a difference between the first distance and the second distance.

Wherein the position correcting unit comprises: a pulse receiving unit for receiving the second ultra violet laser pulse;

A waveform analyzer for analyzing waveforms of the microwave laser pulses received by the pulse receiving unit to determine the degree of occurrence of temporal chirping and PFT; a waveform analyzer for analyzing the degree of occurrence of temporal chirp and the degree of PFT generated by the waveform analyzer; And a driving unit for driving at least one of the first distance and the second distance by driving according to a control signal of the controller.

The first distance and the second distance are at least 20 mm and at most 250 mm, and the third distance between the second prism and the third prism is at least 10 mm and at most 250 mm.

Wherein the distortion compensating optical system includes a first distance adjusting unit located between the first prism and the second prism and operating in accordance with the driving of the driving unit to adjust the first distance and a second distance adjusting unit located between the third prism and the fourth prism, And a second distance adjuster that operates according to the driving of the driving unit to adjust the second distance.

According to the embodiment of the present invention, it is possible to easily correct the spatial chirp generated in the microwave laser pulse. Also, according to the embodiment of the present invention, it is possible to perform high-density fine processing by using a microwave laser such as a femtosecond laser.

1 is a diagram showing a first example of use of an optical system for distortion compensation of an ultra-violet laser pulse according to an embodiment of the present invention.
2 is a diagram showing a second example of use of an optical system for distortion compensation of a microwave laser pulse according to an embodiment of the present invention.
3 is a detailed configuration diagram of an optical system for distortion compensation of an ultra-violet laser pulse according to the first embodiment of the present invention.
4 is a detailed configuration diagram of an optical system for distortion compensation of a microwave laser pulse according to a second embodiment of the present invention.
5 is a configuration diagram of an optical system for compensating distortion of an ultra-violet laser pulse according to a third embodiment of the present invention.
6 is a configuration diagram of an optical system for distortion compensation of an ultra-violet laser pulse according to a fourth embodiment of the present invention.
7 is a configuration diagram of an optical system for distortion compensation of an ultra-violet laser pulse according to a fifth embodiment of the present invention.
8 is a graph showing distortion compensation test results for an output pulse of an optical system for distortion compensation of an ultra-violet laser pulse according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Hereinafter, an optical system for distortion compensation of a microwave laser pulse according to an embodiment of the present invention will be described with reference to the accompanying drawings.

Prior to the description, distance and spacing are shown separately. The distance is the distance traveled by the laser pulse, and the distance is the distance between objects.

An example in which an optical system for distortion compensation of an ultra-violet laser pulse according to an embodiment of the present invention is used will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a diagram showing a first example of use of an optical system for compensating distortion of an ultra-violet laser pulse according to an embodiment of the present invention. In the second embodiment.

Generally, a distorted femtosecond laser pulse is output through a processing optical system 20 for processing or other processing, such as a laser pulse irradiated by a microwave laser, for example, a femtosecond laser 10. At this time, the distortion generated in the femtosecond laser pulse is the spatial chirp. Here, the processing optical system 20 is composed of at least one optical system and is a commonly used optical system, so that detailed description is omitted.

The optical system 100a or 100b for compensating distortion of an ultra-violet laser pulse according to an embodiment of the present invention compensates for the distortion of the femtosecond laser pulse to produce an original orginal femtosecond laser pulse. To this end, an optical system for compensating distortion of an ultra-violet laser pulse according to an embodiment of the present invention is arranged between a processing optical system 20 and a workpiece as shown in FIGS. 1 and 2, and receives a distorted femtosecond laser pulse , And compensates for the spatial chirp of the received femtosecond laser pulse.

First, a first use example of the optical system 100a for distortion compensation of the microwave laser pulse according to the embodiment of the present invention shown in Fig. 1 will be described. Hereinafter, an optical system for compensating distortion of an ultra-violet laser pulse according to an embodiment of the present invention will be abbreviated as a " distortion compensating optical system ".

The distortion-compensating optical system 100a according to the first example of use is for the case where the position-compensating system 200 is not included. That is, the distortion-compensating optical system 100a according to the first embodiment of the present invention does not use the position correction system 200 during the operation using the femtosecond laser pulse.

Specifically, the position correction system 200 is used before using the distortion compensating optical system 100a according to the first use example (ie, before operation), and the four prisms constituting the distortion compensating optical system 100a. Adjust the distance between (P1, P2, P3, P4) and the inclination angle of the prism P4 located at the end of the optical path.

The distance adjustment between the prisms made by the position correction system 200 will correct the spatial chirp, which is the distortion contained in the microwave laser pulses.

The operation of the position correction system 200 will be described in more detail.

The position correction system 200 includes a pulse receiving unit 210, a waveform analyzer 220, a controller 230, and a driving unit 240.

The pulse receiving unit 210 receives the femtosecond laser pulse output from the distortion-compensating optical system 100a. The pulse receiving unit 210 is, for example, a charge-coupled device (CCD) imaging device.

The waveform analyzer 220 analyzes the waveform of the femtosecond laser pulse received by the pulse receiving unit 210 to determine the occurrence of spatial chirp of the femtosecond laser pulse. At this time, the waveform analyzer 200 grasps the degree of occurrence of the spatial chirp by comparing the difference between the original femtosecond laser pulse initially irradiated in the femtosecond laser 10 and the received femtosecond laser pulse.

The controller 230 generates a control signal corresponding to the degree of occurrence of the spatial chirp detected by the waveform analyzer 220 and provides the control signal to the driving unit 240. At this time, the control signal is a first control signal for adjusting the distance between the first prism (P1) and the second prism (P2) (hereinafter referred to as the "first distance"), and between the third prism (P3) and the last prism (P4) At least one of the second control signals for adjusting the distance (hereinafter referred to as "second distance").

At this time, the controller 230 transmits the first control signal and / or the second control signal to the driving unit 240 to change the first distance and the second distance to be different.

The driver 240 is an actuator, and physically adjusts a first distance between the prism P1 and the prism P2 according to the first control signal, and according to the second signal, the prism P3 and the prism P4. Adjust the second distance of the liver.

Here, the adjustment of the first distance and the second distance changes the second distance based on the first distance, or changes the first distance based on the second distance. Of course, even if the first distance or the second distance is used as a reference, if the spatial chirp is not compensated for satisfactorily despite the change of the second distance or the first distance, The second distance or the first distance is changed.

For example, referring to the case where the minimum of the first and second distances is 20 mm and the maximum value is 100 mm based on the first distance, the first distance is 20 mm and the second distance is 21 mm, 22 mm, ..., 100 mm. Change the value to determine the reward of the spatial chirp. At this time, if the compensation of the spatial chirp is unsatisfactory, adjust the second distance to, for example, 25 mm, and then change the second distance to 21 mm, 22 mm, ..., 100 mm.

As a result, by adjusting the first distance and the second distance to be different from each other, the femtosecond laser pulse output from the distortion-compensating optical system 100a is compensated for the spatial chirp.

According to a first use example of the present invention, when the adjustment of the first distance and the second distance is performed so that the femtosecond laser pulse is corrected so that the distortion of the spatial chirp is satisfactorily corrected, Lt; RTI ID = 0.0 > 240 < / RTI >

Next, a second use example of the optical system 100b for distortion compensation of the microwave laser pulse according to the embodiment of the present invention shown in Fig. 2 will be described.

The distortion-compensating optical system 100b according to the second use example is for the case including the position correcting unit 200. [ That is, the distortion-compensating optical system 100b according to the second embodiment of the present invention performs the operation using the position correcting unit 200 while performing the operation using the femtosecond laser pulses.

To this end, the distortion compensating optical system 100b according to the second embodiment of the present invention includes a distortion compensating optical system 100a, a position correcting unit 200 and a duplicating unit 300. [

Here, since the distortion compensating optical system 100a is the same as the distortion compensating system 100a of the first use example, the same reference numerals are given thereto, and the position correcting unit 200 is also provided with the position correcting unit 200 described in the first use example, And therefore are denoted by the same reference numerals.

The distortion compensating optical system 100b according to the second example of use has a duplication unit 300 for use with the position correcting unit 200 in operation. The duplication unit 300 branches the femtosecond laser pulse R outputted from the distortion compensating optical system 100a to two pulses R1 and R2 and the branched one femtosecond laser pulse R1 is irradiated And the other femtosecond laser pulse R2 is received by the position correcting unit 200. [

Here, the intensity of the femtosecond laser pulse R1 irradiated to the work object is lowered by the branching by the duplication unit 300 as compared with the intensity of the femtosecond laser pulse R output from the distortion compensating optical system 100a. If the difference between the intensity of the femtosecond laser pulse R output from the distortion compensating optical system 100a and the intensity of the femtosecond laser pulse R1 irradiated to the work target becomes severe, the desired quality of work cannot be obtained. Therefore, the difference in intensity between the output femtosecond laser pulse R and the femtosecond laser pulse R1 irradiated to the work object is made small so as not to affect the operation.

The femtosecond laser pulse R1 branched by the duplication unit 300 and irradiated to the work is used for work and the femtosecond laser pulse R2 received by the position corrector 200 is used for distortion correction.

The position correction unit 200 analyzes the received femtosecond laser pulse R2 and compensates (ie, removes) the distortion (ie, the spatial chirp) included in the femtosecond laser pulse by the distortion compensation optical system 100a. If the distortion component still remains, the first and second distances between the prisms constituting the distortion compensation optical system 100a are controlled by controlling the operation of the driving unit 240 to compensate for the distortion.

The distortion compensating optical system 100a, the duplicating unit 300 and the position correcting unit 200 form a closed loop so that the femtosecond laser pulse output from the distortion compensating optical system 100a is output to the position correcting unit 200) and compensates for the spatial chirp of the femtosecond laser pulse by grasping the distortion component of the feedback femtosecond laser pulse.

Hereinafter, an optical system for compensating distortion of an ultra-violet laser pulse according to a first embodiment of the present invention will be described with reference to FIGS. 3 to 6. FIG.

3 is a detailed configuration diagram of an optical system for distortion compensation of an ultra-violet laser pulse according to the first embodiment of the present invention. 3, the distortion compensating optical system 100 according to the first embodiment of the present invention is composed of four first through fourth prisms P1, P2, P3, and P4.

The first prism P1 is installed at a position where a distorted femtosecond laser pulse is incident.

The second prism P2 is installed in the straight direction of the femtosecond laser pulse passing through the first prism P2. At this time, the distance L1 between the first prism P1 and the second prism P2 is a minimum of 20 mm to a maximum of 250 mm.

The third prism P3 is installed in the straight-ahead direction of the femtosecond laser pulse passing through the second prism P2. At this time, the distance L2 between the second prism P2 and the third prism P3 is at least 10 mm to at most 250 mm.

The fourth prism P4 is installed in the straight-ahead direction of the femtosecond laser pulse passing through the third prism P3. At this time, the distance L3 between the third prism P3 and the fourth prism P4 is at least 20 mm and at most 250 mm.

Here, the first to fourth prisms P1, P2, P3 and P4 of the distortion compensating optical system 100a according to the first embodiment of the present invention are already distorted by the femtosecond laser pulse , And to compensate for spatial chirp. That is, the first to fourth prisms P1 to P4 are arranged at fixed positions.

Specifically, when the arrangement relationship between the temporal chirp of the femtosecond laser pulse and the first to fourth prisms P1 to P4 compensating for the PTF, the first prism P1 and the second prism (for compensating the temporal chirp) The distance L1 between P2 and the distance L3 between the third prism P3 and the fourth prism P4 are arranged to be different.

Next, with reference to FIG. 4, an optical system for distortion compensation of an ultra-violet laser pulse according to a second embodiment of the present invention will be described.

4 is a detailed configuration diagram of an optical system for distortion compensation of a microwave laser pulse according to a second embodiment of the present invention. 4, the distortion compensating optical system 100a according to the second embodiment of the present invention includes four first through fourth prisms P1, P2, P3 and P4, two first and second prisms P1, P2, 2 distance adjusting unit.

The first to fourth prisms P1 to P4 are identical to the first to fourth prisms of the first embodiment and are given the same reference numerals.

The first distance adjustment unit is located between the first prism P1 and the second prism P2 and the second distance adjustment unit is located between the third prism P3 and the fourth prism P4. The first and second distance adjusters adjust the distance between the prisms.

To this end, each of the first and second distance adjusters includes four reflective mirrors and one moving stage in pairs.

Specifically, the first distance adjusting unit includes four reflecting mirrors M11, M12, M13, and M14 and a first moving stage 110 that are paired.

The reflection mirror M11 is provided in the straight direction of the femtosecond laser pulse passing through the first prism P1 and reflects the incident femtosecond laser pulse at a set angle. The reflection mirror M12 is provided in the straight direction of the femtosecond laser pulse reflected by the reflection mirror M11 and reflects the incident femtosecond laser pulse at a set angle. The reflection mirror M13 is provided in the straight direction of the femtosecond laser pulse reflected by the reflection mirror M12 and reflects the incident femtosecond laser pulse at a set angle. The reflection mirror M14 is provided in the straight-ahead direction of the femtosecond laser pulse reflected by the reflective mirror M13 and reflects the incident femtosecond laser pulse at a set angle to advance to the second prism P2. Here, the reflective mirrors M11 and M14 are fixedly installed between the first and second prisms P1 and P2, and the reflective mirrors M12 and M13 are installed on the first moving stage 110.

The second distance adjusting unit includes four reflecting mirrors M21, M22, M23, M24 and a first moving stage 120 which are paired.

The reflection mirror M21 is installed in the straight direction of the femtosecond laser pulse passing through the third prism P1 to reflect the incident femtosecond laser pulse at a predetermined angle. The reflection mirror M22 is provided in the straight direction of the femtosecond laser pulse reflected by the reflection mirror M21 and reflects the incident femtosecond laser pulse at a set angle. The reflection mirror M23 is provided in the straight direction of the femtosecond laser pulse reflected by the reflection mirror M22 and reflects the incident femtosecond laser pulse at a set angle. The reflection mirror M24 is provided in the straight-ahead direction of the femtosecond laser pulse reflected by the reflection mirror M23 and reflects the incident femtosecond laser pulse at a predetermined angle to advance to the fourth prism P4. Here, the reflection mirrors M21 and M24 are fixedly installed between the third and fourth prisms P3 and P4, and the reflection mirrors M22 and M23 are installed on the second moving stage 120.

Meanwhile, the first moving stage 110 moves forward and backward according to the driving of the first linear actuator 241 of the driving unit 240. The distance between the reflective mirrors M12 and M13 provided on the first moving stage 110 and the reflective mirrors M11 and M14 is narrowed and the reflective mirrors M12 and M13 provided on the first moving stage 110 when moving backward, The interval between the reflection mirrors M11 and M14 is widened.

Therefore, the distance L11 between the first prism P1 and the second prism P2 is shortened when the first moving cage 110 moves forward, and the first prism P1 and the second prism P2 when moved backward. The distance L11 between) becomes long.

Here, the distance L11 between the first prism P1 and the second prism P2 is the distance that the femtosecond laser pulse is moved between the first prism P1 and the second prism P2.

In addition, the second stage 120 moves forward and backward according to the driving of the second linear actuator 242 of the driving unit 240. Like the first stage 110, the second stage 120 shortens the distance L31 between the third prism P3 and the fourth prism P4 during the forward movement, and the third prism P3 and the third during the backward movement. 4 Make the distance L31 between the prisms P4 longer. Of course, the distance L31 between the third prism P3 and the fourth prism P4 is the distance that the femtosecond laser pulse is moved between the third prism P3 and the fourth prism P4.

The first through fourth prisms P1, P2, P3, and P4 and the first and second distance adjusters of the distortion compensating optical system 100a according to the second embodiment of the present invention are disposed in the position correcting section 200 To compensate for the distortion of the femtosecond laser pulse, that is, the spatial chirp.

The first to fourth prisms P1 to P4, the reflection mirrors M11 to M14 and M21 to M24 and the first and second moving stages 110 and 120 are fixed in position to compensate for the temporal chirp and the PTF Respectively.

Specifically, in order to compensate for the temporal chirp, the distance L11 between the first prism P1 and the second prism P2 and the distance L31 between the third prism P3 and the fourth prism P4 are different from each other. It is arranged for me.

At this time, the distance L11 between the first prism P1 and the second prism P2 and the distance L31 between the third prism P3 and the fourth prism P4 are at least 20 mm and at most 250 mm. The distance L2 between the second prism P1 and the third prism P3 is at least 10 mm and at most 250 mm.

Hereinafter, a third embodiment and a fourth embodiment of the present invention will be described with reference to FIGS. 5 and 6. FIG.

5 is a configuration diagram of an optical system for compensating distortion of an ultra-violet laser pulse according to a third embodiment of the present invention. As shown in FIG. 5, the third embodiment of the present invention is for the case where the first distance adjuster is removed in the second embodiment of the present invention.

That is, the distortion-compensating optical system 100a according to the third embodiment of the present invention includes four prisms P1 to P4 and a distance adjusting unit , And a second distance adjustment unit).

That is, the first prism P1 is installed at the position where the distorted femtosecond laser pulse is incident, and the second prism P2 is installed in the straight direction of the femtosecond laser pulse passing through the first prism P2. The third prism P3 is provided in the straight direction of the femtosecond laser pulse passing through the second prism P2 and the second distance adjuster is provided between the third prism P3 and the fourth prism P4.

The first through fourth prisms P1, P2, P3, and P4 and the second distance adjuster of the distortion compensating optical system 100a according to the third embodiment of the present invention are already aligned with the femtosecond laser Are arranged to compensate for the spatial chirp of the pulse.

That is, to compensate for the temporal chirp, the distance L1 between the first prism P1 and the second prism P2 and the distance L31 between the third prism P3 and the fourth prism P4 are different from each other. It is arranged. At this time, the distance L1 between the first prism P1 and the second prism P2 and the distance L31 between the third prism P3 and the fourth prism P4 are at least 20 mm and at most 250 mm.

6 is a configuration diagram of an optical system for distortion compensation of an ultra-violet laser pulse according to a fourth embodiment of the present invention. As shown in FIG. 6, the fourth embodiment of the present invention is the case where the second distance adjuster is removed in the second embodiment of the present invention.

That is, the distortion compensation optical system 100a according to the fourth embodiment of the present invention includes four prisms P1 to P4 and a distance adjusting unit (ie, disposed between the first prism P1 and the second prism P2). , The first distance control unit).

A first distance adjusting unit is provided between the first prism P1 and the second prism P2 and a third prism P3 is provided in a straight line direction of the femtosecond laser pulse passed through the second prism P2. The fourth prism P4 is installed in the straight direction of the femtosecond laser pulse passing through the first prism P2 passing through the third prism P3.

The first through fourth prisms P1, P2, P3, and P4 and the first distance adjustment unit of the distortion compensating optical system 100a according to the fourth embodiment of the present invention are already aligned by the position correcting unit 200 with the femtosecond laser Are arranged to compensate for the spatial chirp of the pulse.

That is, to compensate for the temporal chirp, the distance L11 between the first prism P1 and the second prism P2 and the distance L3 between the third prism P3 and the fourth prism P4 are different from each other. It is arranged. At this time, the distance L11 between the first prism P1 and the second prism P2 and the distance L3 between the third prism P3 and the fourth prism P4 are at least 20 mm and at most 250 mm.

Hereinafter, the distortion compensating optical system 100b according to the second embodiment of the present invention described with reference to FIG. 2 will be described in more detail with reference to FIG.

7 is a configuration diagram of an optical system for distortion compensation of an ultra-violet laser pulse according to a fifth embodiment of the present invention. 7, the distortion compensating optical system 100b according to the fifth embodiment of the present invention includes a distortion compensating optical system 100a, a position correcting unit 200, and a duplicating unit 300. [

The distortion compensation optical system 100a is the same as the distortion compensation system 100a according to the first use example of the present invention. That is, the distortion-compensating optical system 100a is one of the distortion-compensating optical systems 100a according to the first to fourth embodiments of the present invention.

The position correcting unit 200 includes a pulse unit 210, a waveform analyzer 220, a controller 230, and a driving unit 240. Each of the positions of the position correcting unit 200 is shown in FIG. I have omitted it, so I will omit it.

The duplication unit 310 transforms one femtosecond laser pulse R passed through (that is, transmitted through) the fourth prism P4 of the distortion-compensating optical system 100a into two pulses R1 and R2, To be input to the job target and the position correcting unit 200 via the path.

To this end, the duplication unit 310 includes a beam splitter 310 positioned in a straight line direction of the femtosecond laser pulse R transmitted through the fourth prism P4. Of course, instead of the beam splitter 310, the duplication unit 310 may use an optical device, such as the beam splitter 310, that converts one pulse into a plurality of pulses. According to the arrangement of the position between the duplication unit 310 and the position correction unit 200, the depletion unit 310 may further include at least one reflection mirror in addition to the beam splitter 310.

The beam splitter 310 reflects a portion R1 of the incident femtosecond laser pulse R and irradiates the portion R1 with respect to an object to be worked so as to transmit a part R2 to the incident femtosecond laser pulse R, 200).

At this time, the femtosecond laser pulse R1 irradiated to the work object does not have a large difference in intensity from the incident femtosecond laser pulse R. In general, the two lights output by the beam splitter can have about 95% of one light and about 5% of the other light, compared to the original light.

When the femtosecond laser pulse R2 is received, the position correcting unit 200 analyzes the received femtosecond laser pulse R2 to correct the distortion included in the femtosecond laser pulse by the distortion-compensating optical system 100a, . The position correcting unit 200 controls the operation of the driving unit 240 through the controller 230 to compensate for the distortion if the distortion component remains in the femtosecond laser pulse R2.

Accordingly, the linear drivers 241 and 242 and the rotary driver 243 of the driving unit 240 are driven according to the control signal of the controller 230 to drive the first and second moving stages 110 and 120 or the second prism P4. ).

The operation of the position correcting unit 200 is performed until the spatial chirp of the femtosecond laser pulse is completely compensated.

On the other hand, the configuration of the driving unit 240 of the position correcting unit 200 is configured to be suitable for the configuration of the distortion-compensating optical system 100a.

That is, if the distortion compensating optical system 100a has the configuration according to the first embodiment of the present invention, the driving unit 240 includes only the rotary actuator 243, and when the distortion compensating optical system 100a has the configuration according to the second embodiment of the present invention The backside drive unit 240 includes first and second linear drivers 241 and 242 and a rotation driver 243.

If the distortion compensating optical system 100a has the configuration according to the third embodiment of the present invention, the driving unit 240 includes the rotation driver 243 and the second linear driver 242, The driving unit 240 includes the first linear driver 241 and the rotation driver 243. [

8 is a graph showing distortion compensation test results for an output pulse of an optical system for distortion compensation of an ultra-violet laser pulse according to an embodiment of the present invention.

The femtosecond laser used in this experiment has a pulse width of 87.2 fs and a pulse front tilt (PFT) of 100.8 fs / mm. In order to artificially distort this femtosecond laser pulse, a distorted femtosecond laser pulse with a pulse width of about 192 fs and a PFT of 588 fs / mm was generated using SF11 glass.

After the femtosecond laser pulse having such distortion is irradiated to the distortion compensation system 100a according to the second embodiment of the present invention, the distance L11 between the first and second prisms P1 and P2 to compensate for the temporal chirp. And the distance (L31) between the third and fourth prism (P3, P4) was changed to have a difference.

6 (a) to 6 (c) are views showing the results of such experiments.

FIG. 8A illustrates a case where the distance between the prism P3 and the prism P4 is 8 cm shorter than the distance between the prism P1 and the prism P2, and FIG. 8B illustrates the prism P3. The distance between the prism P4 and the prism P4 is 8 cm longer than the distance between the prism P1 and the prism P2. 8C illustrates a case where the distance between the prism P3 and the prism P4 is made 8 cm longer than the distance between the prism P1 and the prism P2.

As shown in FIG. 8C, when the distance between the prism P3 and the prism P4 is made 8 cm shorter than the distance between the prism P1 and the prism P2, the spatial chirp is -2.66 nm / mm. Was measured. And when the distance between prism P3 and prism P4 was made 8 cm longer than the distance between prism P1 and prism P2, the spatial chirp was measured at 1.98 nm / mm. In addition, when the distance between prism P3 and prism P4 made the distance between prism P1 and prism P2 the same, the spatial chirp was measured at 0.54 nm / mm.

These results show that the spatial chirp can be continuously compensated by changing the distance between the prism P3 and the prism P4 differently between the prism P1 and the prism P2.

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

P1, P2, P3, P4: prism
100a: distortion compensation system, distortion compensation optical system
100b: Distortion compensation system
200:
210:
220: Waveform analyzer
230:
240:
241, 242: linear actuator
300: Duplex part
310: beam splitter
110, 120: mobile station
M11 to M14 and M21 to M24: reflection mirror

Claims (16)

A first prism installed at a position where the microwave laser pulse is incident,
A second prism provided in a straight direction of the microwave laser pulse passing through the first prism,
A third prism provided in a straight direction of the microwave laser pulse passing through the second prism,
A fourth prism provided in a straight direction of the microwave laser pulse passing through the third prism,
A first distance adjuster positioned between the first prism and the second prism to adjust a first distance between the first prism and the second prism; and
A second distance controller positioned between the third prism and the fourth prism to adjust a second distance between the third prism and the fourth prism;
Compensating the spatial chirp by adjusting the distance difference between the first distance and the second distance by operating the first distance adjusting unit and the second distance adjusting unit,
The first distance and the second distance are at least 20 mm to at most 250 mm,
And a third distance between the second prism and the third prism is at least 10 mm to at most 250 mm. delete delete The method of claim 1,
The first distance control unit
First and fourth reflecting mirrors disposed on the laser pulse paths of the first prism and the second prism, and a first moving stage and second and third reflecting mirrors installed on the first moving stage, Compensating for the distortion of the microwave laser pulses such that the microwave laser pulse passing through the first prism forms a pulse path in the order of the first reflection mirror, the second reflection mirror, the third reflection mirror, and the fourth reflection mirror. For optical system. 5. The method of claim 4,
The second distance adjusting unit
And fifth and eighth reflecting mirrors provided on the laser pulse paths of the third prism and the fourth prism, and sixth and seventh reflecting mirrors installed on the second moving stage and the second moving stage. Compensating for the distortion of the microwave laser pulses such that the microwave laser pulse passing through the three prisms forms a pulse path in the order of the fifth reflection mirror, the sixth reflection mirror, the seventh reflection mirror, and the eighth reflection mirror. For optical system.
delete delete delete delete delete delete delete delete delete delete delete

Images