JP2003047841A - Surface stripping and cleaning method using ultra short pulse laser and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface stripping and cleaning method, by which surface stripping and cleaning requiring fine and careful work is performed precisely for a short time. SOLUTION: The surface stripping and cleaning method is used for stripping and cleaning a unnecessary material stuck on the surface of a material to be cleaned. The unnecessary material is irradiated with ultra short pulse laser to excite the unnecessary material and to cause the drastic increase in shear between the material to be cleaned and the unnecessary material and as a result, the unnecessary material is fragmented and stripped from the surface of the material to be cleaned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The invention of this application relates to a surface peeling cleaning method. More specifically, the invention of this application relates to a method for surface peeling cleaning using an ultrashort pulse laser, which is useful for selectively cleaning only a portion requiring cleaning with extremely fine accuracy.

[0002]

2. Description of the Related Art With respect to classical paintings, ruins, fossils, etc., which have a high historical value, it is often necessary to remove and remove unnecessary substances adhering to the surface without damaging the substance. However, there has been a problem that these operations require a great deal of time and labor.

For example, in classical paintings, pigments such as varnishes and paints are applied over multiple layers by repeated restoration. Therefore, in the restoration of classical paintings, it is essential to remove pigments applied in multiple layers. The work of removing only the unnecessary pigment so as not to damage the original image needs to be performed extremely carefully, and is realized by the steady manual work of an expert.

[0004] The work of peeling and cleaning the unnecessary substances by hand is extremely labor intensive, costly, and requires a long period of time. Therefore, the invention of this application has been made in view of the circumstances as described above, and a surface peeling cleaning method for realizing accurate and short-time surface peeling cleaning that requires delicate and careful work. The challenge is to provide.

[0005]

In order to solve the above-mentioned problems, the invention of the present application is, firstly, a surface peeling cleaning method for peeling and cleaning unnecessary substances adhering to the surface of an object to be cleaned. And excite unnecessary objects by irradiating the ultra-short pulse laser, causing a rapid stress increase between the objects to be cleaned and the unnecessary objects to be fragmented and separated from the surface of the object to be cleaned. There is provided a surface peeling cleaning method.

Secondly, the invention of this application is a surface peeling and cleaning method for peeling and cleaning unnecessary substances adhering to the surface of an object to be cleaned. Thirdly, the surface peeling cleaning method is characterized by comparing the spectrum of scattered light intensity on the surface of the object to be cleaned and irradiating the unnecessary object with an ultra-short pulse laser until they differ. There is provided a surface peeling cleaning method.

Further, the invention of this application is, fourthly, a surface peeling cleaning apparatus for peeling and cleaning unnecessary substances adhering to the surface of an object to be cleaned, which is for irradiating the unnecessary substances with an ultrashort pulse laser. With the ultra-short pulse laser light source, the unnecessary portion is excited by the irradiation of the ultra-short pulse laser from the ultra-short pulse laser light source, and a sudden stress rise occurs between the object to be cleaned and the unnecessary object, Fifth, a surface peeling cleaning device for peeling and cleaning unnecessary objects adhering to the surface of the cleaning target, which is characterized by fragmenting and peeling from the surface of the cleaning target It is equipped with an ultra-short pulse laser light source for irradiating an object with an ultra-short pulse laser and a spectroscopic spectrum measuring device for measuring the spectral spectrum of the scattered light intensity on the surface of the object to be cleaned. Before and after laser irradiation, measure the spectrum of scattered light intensity on the surface of the object to be cleaned with a spectroscopic measuring instrument, and continue to irradiate the ultra-short pulse laser to the unwanted matter until the non-spectral spectrum before and after the ultra-short pulse laser irradiation is different. Sixthly, the present invention provides a surface peeling cleaning apparatus, and sixthly, a surface painting cleaning apparatus for classical paintings.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The invention of this application has the characteristics as described above, and the embodiments thereof will be described below.

In the surface peeling cleaning method of the invention of this application, the unnecessary matter attached to the surface of the object to be cleaned is irradiated with the ultrashort pulse laser to peel off the unnecessary object from the surface. As the ultrashort pulse laser in this case, a femtosecond laser and a picosecond laser are typically exemplified. FIG. 1 is a schematic diagram showing the principle of the surface peeling cleaning method of the invention of this application. In this example,
By exciting the unnecessary substance (2) by the femtosecond laser (1), a rapid stress increase occurs between the cleaning target (3) and the unnecessary substance (2). Due to the generated stress, the unnecessary material (2) existing in the laser irradiation portion is fragmented and peeled off from the surface of the cleaning object (3).

FIG. 2 is a diagram showing an etching shape when an organic solid is irradiated with a femtosecond laser. Figure 3
As a comparative example, the etching shape when an organic solid is irradiated with a nanosecond laser is shown in FIG. It can be seen that irradiation with a femtosecond laser realizes more discrete etching as compared with irradiation with a nanosecond laser. This is because abrupt stress change occurs in the organic solid by performing the femtosecond laser irradiation based on the above principle. Similarly, when the picosecond laser is irradiated, discrete etching is realized.

FIG. 4 is a diagram showing an ablation process when an organic solid is irradiated with a femtosecond laser and when irradiated with a nanosecond laser. When the nanosecond laser is irradiated, a rapid temperature rise occurs about 10 nanoseconds after the laser excitation, and the organic solid surface is thermally etched. On the other hand, when femtosecond laser excitation is performed, destruction due to a rapid rise in internal stress occurs before a large heat rise occurs. Therefore, the inside of the organic solid is fragmented and discrete etching is performed. Utilizing the above phenomenon, in the surface peeling cleaning method of the invention of this application, only unnecessary substances are accurately removed. That is, since the laser to be irradiated is an ultra-short pulse laser, contamination of the surface of the object to be cleaned does not occur due to thermal melting of the unnecessary object, and the unnecessary object is selectively fragmented and peeled from the surface of the object to be cleaned. It becomes possible.

In the surface peeling cleaning method of the invention of this application, in order to clean the object to be cleaned automatically without human intervention as much as possible, before and after the irradiation of the ultrashort pulse laser to the unnecessary object, respectively. It is considered to measure spectroscopic spectra of scattered light intensity on the surface of the object to be cleaned and compare them. By comparing the spectral spectra before and after the irradiation with the ultrashort pulse laser and continuing the irradiation with the ultrashort pulse laser on the unwanted matter until they differ, the removal of the unwanted matter is automatically checked.

FIG. 5 shows an example of the structure of a surface peeling cleaning apparatus for realizing the surface peeling cleaning method of the invention of the present application described above. Further, FIG. 6 is a flow chart showing a procedure of surface peeling cleaning by the apparatus shown in FIG.

The object to be cleaned (51) is an XY stage (5
2) Installed on top. The laser light for optical path guide emitted from the laser for optical path guide (53) is fixed so as to irradiate the coordinates on the surface of the cleaning object (51) irradiated by the femtosecond laser light, for example.

First, a CCD camera (54) photographs the portion indicated by the laser light for optical path guide, and visually confirms the photographed image to determine whether or not cleaning is necessary. When it is determined that the cleaning is necessary, the laser light output from the femtosecond laser light source (55) is separated into two by the half mirror (56), and one of them is an unnecessary material (57) on the surface of the cleaning object (51). ) Is irradiated to the unwanted matter (57) as a peeling laser beam for peeling off), and the other branched laser beam is the white light generator (5).
It is input to 8) and is irradiated as white laser light to the unwanted matter (57). The shutter (59) controls the irradiation time of the laser light for peeling onto the cleaning object (51). In addition, by the light intensity adjusting device (60),
The peeling laser light intensity is controlled.

The spectral spectrum of the diffusely reflected light of the white laser light applied to the object to be cleaned (51) is measured by the spectral spectrum measuring device (61). This spectroscopic spectrum represents the surface condition of the surface of the object to be cleaned (51) at the laser irradiation portion. Before the peeling laser light is irradiated, the spectrum is measured in advance, and compared with the spectrum after the peeling laser light is irradiated, irradiation of the peeling laser is continued until these are sufficiently different. repeat. The above peeling cleaning is repeated while scanning the XY stage (52) to clean the surface of the cleaning object (51).

In this surface peeling cleaning device, the CCD
The image information obtained by the camera (54) and the spectral spectrum measured by the spectral spectrum measuring device (61) are input to the central controller (62). A control signal is sent from the central control device (62) to the XY stage (52), the shutter (59), and the light intensity adjusting device (60) based on the input information, and the semi-automatic peeling is performed. A cleaning process is performed.

The surface peeling cleaning method according to the invention of this application has various uses such as restoration of works of art such as classical paintings, cleaning of deposits such as fossils and excavated remains, cleaning of paints, cleaning of precision instruments, etc. It goes without saying that things are taken into consideration. The surface peeling cleaning method that is the invention of this application is particularly suitable when the attached unnecessary substances are minute, and is a method that utilizes stress rise with little thermal influence, and the cleaning target can be contaminated by the unnecessary substances. Very low in sex. Further, by automating the cleaning evaluation by laser spectroscopy, the working time can be significantly shortened as compared with the manual work.

[0019]

As described in detail above, the invention of the present application provides a surface peeling cleaning method which realizes accurate and short-time surface peeling cleaning which requires delicate and careful work. The invention of this application realizes semi-automation of work that has been performed only by steady manual work, and puts highly accurate and highly efficient surface peeling cleaning into practical use.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the principle of a surface peeling cleaning method according to the invention of this application.

FIG. 2 is a diagram showing an etching shape when an organic solid is irradiated with a femtosecond laser.

FIG. 3 is a diagram showing an etching shape when an organic solid is irradiated with a nanosecond laser.

FIG. 4 is a graph showing an ablation process when an organic solid is irradiated with a femtosecond laser and when irradiated with a nanosecond laser.

FIG. 5 is a schematic diagram showing an example of a configuration of a surface peeling cleaning apparatus of the invention of this application.

FIG. 6 is a flow chart showing a procedure of surface peeling cleaning by the apparatus shown in FIG.

[Explanation of symbols]

1 femtosecond laser 2 unnecessary material 3 Cleaning target 51 Cleaning target 52 XY stage 53 Laser for optical path guide 54 CCD camera 55 femtosecond laser light source 56 half mirror 57 unwanted material 58 White light generator 59 shutter 60 Light intensity controller 61 Spectroscopic spectrum measuring device 62 Central controller

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoichiro Hosokawa             719-8 Kusakabe, Dojo Town, Kita Ward, Kobe City, Hyogo Prefecture (72) Inventor Yutaka Matsumoto             2-33 Ginza-cho, Fushimi-ku, Kyoto-shi, Kyoto Prefecture (72) Inventor Hiroshi Masuhara             2-4-16 Minamikonoike-cho, Higashiosaka-shi, Osaka Prefecture (72) Inventor Setsuya Sato             2-9-23 Biugaoka, Takatsuki City, Osaka Prefecture F term (reference) 3B116 AA46 AB01 BB71 BC01                 4G075 AA30 AA70 BA05 CA36

Claims (6)

[Claims] 1. A surface peeling cleaning method for peeling and cleaning unnecessary substances adhering to the surface of an object to be cleaned, wherein the unnecessary substances are excited by irradiation of an ultrashort pulse laser, and A surface peeling cleaning method, characterized in that a rapid increase in stress is generated in the meantime to fragment unnecessary substances and peel off from the surface of an object to be cleaned. 2. A surface peeling cleaning method for peeling and cleaning an unnecessary object adhered to the surface of the cleaning object according to claim 1, wherein scattering of the surface of the cleaning object before and after irradiation of the ultrashort pulse laser with respect to the unnecessary object. A surface peeling cleaning method, which comprises comparing light intensity spectrums and irradiating an unnecessary object with an ultra-short pulse laser until they differ. 3. The surface peeling cleaning method according to claim 1 or 2, wherein the surface peeling cleaning of a classical painting is performed. 4. A surface peeling cleaning method for peeling and cleaning an unnecessary substance adhering to the surface of an object to be cleaned, comprising: an ultra-short pulse laser light source for irradiating the unnecessary substance with an ultra-short pulse laser, Irradiating an ultra-short pulse laser from a short pulse laser light source excites unnecessary parts, causing a rapid stress increase between the objects to be cleaned, fragmenting the objects and peeling them from the surface of the object to be cleaned. A surface peeling cleaning device characterized by the above. 5. A surface peeling cleaning apparatus for peeling and cleaning an unnecessary object adhered to the surface of an object to be cleaned according to claim 4, wherein the ultrashort pulse laser light source for irradiating the unnecessary object with an ultrashort pulse laser. And a spectroscopic spectrum measuring instrument for measuring the spectroscopic spectrum of the scattered light intensity on the surface of the object to be cleaned. A surface peeling cleaning device characterized by measuring the spectroscopic spectrum of, and continuing the irradiation of the ultrashort pulse laser on the unwanted matter until the non-spectral spectrum before and after the irradiation of the ultrashort pulse laser. 6. The apparatus according to claim 4 or 5, wherein the surface peeling cleaning apparatus performs the surface peeling cleaning of a classical painting.