JPS63163304A - Laser light absorptive glass filter - Google Patents

Abstract

PURPOSE:To provide the titled glass filter which is not broken in a short period when subjected to direct irradiation of lasers of middle and small outputs by forming the filter of a glass material which contains a laser light absorptive component and contains >=90wt.% SiO2. CONSTITUTION:The content of SiO2 in the glass filter contg. the laser light absorptive component is specified to >=90wt.%. The filter is, therefore, capable of maintaining the physical property as quartz glass, i.e., a high m.p. and low coefft. of expansion even if the filter contains the laser light absorptive component. Generation of a crack arising from the melting of the irradiated part and the local thermal melting thereof is thereby effectively prevented even if the laser of the middle or small output, for example, about 50W, is directly projected to the local part of the filter. Generation of the failure in the filter by the direction irradiation for a short period is thus obviated.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a glass filter used for protective glasses or shielding members against laser beams.

(Conventional technology and its problems) Conventionally, laser light absorption filters have been molded by kneading organic laser light absorption dyes into synthetic resins such as polycarbonate or acrylic resin, or by molding laser light absorption filters into soda lime glass or borosilicate glass. Molded products with added light-absorbing components are used.

However, when such filters are irradiated with a laser beam with high energy density, the irradiated area of synthetic resin filters melts and holes form, and even in the case of glass filters, the irradiated area becomes partially heated. It will expand and destroy the entire filter. For this reason, there was a risk that not only the function as a filter would be lost, but also fatal accidents such as blindness could occur.

In particular, in recent years, as small and medium-sized output laser devices such as medical lasers and experimental lasers have become widespread, such a risk has been strongly pointed out.

The present invention was developed in view of the above problems, and is designed to be able to withstand direct irradiation with a small to medium output laser without being damaged in a short period of time.
It is an object of the present invention to provide a laser light absorption filter that allows danger prevention actions to be easily taken before succumbing to damage.

(Means for Solving the Problems) The filter of the present invention taken to achieve the above object is made of a glass material that has a laser beam absorption component and has a 5i02 content of 90% by weight or more. It is a configuration that is formed.

(Function) In the composition of the glass filter, the 5t02 content is 9
0% by weight or more, it is possible to maintain the physical properties of quartz glass, such as a high melting point and a low coefficient of expansion, even though it has a laser beam absorption component.
Even if the filter is locally directly irradiated with a small to medium output laser of about W, it can effectively prevent the melting of the irradiated part and the occurrence of cracks due to local thermal expansion. No damage to the filter.

(Example) The glass filter of the present invention has a laser light absorbing component in its composition, and the SiO□ content is 90ffi% or more.

If the 5i02 content is less than 90%, the physical properties of quartz glass will deteriorate significantly, making it impossible to secure the required high melting point and low expansion coefficient, and there is a risk of damage due to direct irradiation with a laser beam with an output of 50 W. This is because there is.

In the present invention, the standard output of a medical laser is 5.
The glass composition was limited to 0 W as a reference, and the glass composition must not be damaged by direct irradiation with a laser beam at this output for 1 minute.

Examples of laser light absorption components include cadmium sulfide, cobalt ions, and gold colloids for argon lasers, copper ions and cobalt ions for ruby lasers, and Nd-Y.
Copper ions and iron ions can be used as examples for AG lasers, and iron ions, titanium ions, and chromium ions can be used as examples for CO and lasers.

The content of these light-absorbing components is preferably in the range of 0.1 to 5% by weight. If it is less than 0.1%, the amount of light absorbed will be small, while if it exceeds 5%, the absorbance of laser light will increase, but the transmittance of visible light will also decrease, making it difficult to see the object through the filter. becomes.

Note that it is desirable that the laser light absorbing component be contained so that the absorbance is 4 or more. The reason for this is that if the time it takes for the human body to sense an abnormality and take protective action when looking directly at a laser beam with an output of 50W is 0.25 seconds, ANSr(
Eight MHI? ICAN NATIONAL 5TAN
DARRO ■N5TITtlTE Z -136,1
) 980), the absorbance needs to be 4 or more. Here, maximum permissible exposure refers to the energy level of laser radiation that the human body may be exposed to without dangerous effects on the eyes or skin or harmful biological changes.

The filter glass according to the present invention can be manufactured by melting a mixture of light-absorbing component powder and crystal powder, but if it is difficult to add the light-absorbing component alone, it may be necessary to melt the mixture of the light-absorbing component powder and quartz crystal powder. By mixing and melting this glass powder with quartz powder, a product having the desired composition can be easily obtained.

Incidentally, in order to reduce the filter transmittance of laser light, it is effective not only to include a laser light absorbing component but also to form a reflective film that reflects laser light on the filter surface. This reflective film may be formed on either the incident side or the transmission side (the side opposite to the incident side), but it is preferable to form it on the latter surface because it is less likely to be damaged by direct laser beam irradiation. . Alternatively, two filters may be used by polymerizing them with a reflective film interposed therebetween.

Note that forming only a reflective film on the surface of quartz glass that does not contain any laser light absorbing components will result in damage from direct laser light irradiation, as the quartz glass itself has almost no light absorbing properties, and as a result, it will cause damage to occur from the damaged area. This is not preferable because the energetic laser light is transmitted through it.

Specific examples of substances forming the reflective film include argon laser, ruby laser, Nd-YAG laser,
Gold, silver, Aff, Mg (alone or in combination) for CO□ lasers and Cu for CO2 lasers.

Mo is Zn for argon laser and ruby laser
An S-MgF2-based interference film is effective, and an 8g MgF2-Ag-based interference film is effective for an IJd-YAG laser.

The reflective film is formed to a thickness of several tens to several thousands of layers using a thin film forming method such as vacuum deposition or ion blating.

Further, it is preferable to form a photosensitive layer on the entrance side surface of the filter, which causes a change in shape that can be recognized with the naked eye by direct irradiation with laser light, such as a change in color or shape. This is because it becomes easier to recognize the irradiation state of the laser beam and take action to avoid danger. In particular, laser light with invisible wavelengths (e.g., laser light with wavelengths in the infrared or ultraviolet range)
It is valid for

Specific examples of photosensitive layers that undergo a shape change when directly irradiated with laser light include the following.

Polycarbonate for use with argon lasers.

Acrylic resin, styrene resin, vinyl chloride resin.

A transparent synthetic resin such as a cellulose resin is treated with an orange dye such as Kayaset Orange G, Kayaset Orange A-N (both manufactured by Nippon Kayaku Co., Ltd.!I) at 0.01%.
-0.5% by weight added and molded to a thickness of 1 to 3 fins is preferable. For use in ruby lasers, a material obtained by adding 0.01 to 0.5% by weight of a dye such as cryptocyanine to the above synthetic resin and molding it to a thickness of 0.5 to 3 mm is preferable. N
For use with d-YAG lasers, the synthetic resin may include the product name IR-126 (manufactured by American Cyanamids),
IRF-1)00 (manufactured by Fuji Photo Film Co., Ltd.)
0.0 to 0.5% by weight of pigments such as
．． 5-31) Thick molded ones are better. For use in carbon dioxide lasers, the synthetic resin may be used at 0.1
It is best to mold it to a thickness of ~3 mm.

Next, specific examples, comparative examples, and conventional examples will be described. It should be noted that all amounts added and composition percentages are percentages by weight.

<Example 1> (1) Adding 2% copper powder to 98% crystal powder
The mixture was heated and melted at ~2200° C. and poured into a carbon mold to obtain a blue-green filter original plate with a thickness of about 4 mm.

Both sides of this original plate were polished to obtain a glass filter with a thickness of 3 cm.

(2) The absorbance of this glass filter at a wavelength of 1.06 μm was measured and was 4 or more.

The absorbance was measured using an ultraviolet/visible/infrared spectrophotometer. Generally, when the absorbance is 4 or more, a spectrophotometer can only obtain a measured value of 4 or more because it exceeds the measurement sensitivity limit.

Although the output of the +31 Nd-YAG laser was set too high and the beam was irradiated with iV 3 am for 1 minute, no abnormality occurred in the filter.

<Example 2> (ll Example! 8g Mg was deposited on one side of the surface of a glass filter manufactured in the same manner as in (I) by vacuum evaporation.
A F2-g-based reflective film was formed.

(2) Same as Example 1 (2), wavelength 1.06 μm
When the absorbance was measured, it was 4 or more.

(3) Direct irradiation with a laser beam was performed under the same conditions as in Example 1 (3) with the reflective film formation side set as the transmission side, but no abnormality was observed.

<Example 3> (1) Borosilicate glass (composition: 5ift 75%,
Na207%, 820t 15%, ARlz(h 3%
) and Fe was added to give a glass composition of 7% to produce a colored glass.

(2) 20% colored glass powder and 80% quartz powder were mixed, heated and melted at 2000 to 2200°C, and then poured into a mold to obtain a brown filter original plate.

Both surfaces of the filter were polished to obtain a glass filter with a thickness of 3 mm. The composition of this glass filter was as follows.

Stow? 94.0%, Na20:t,
3%, BICh:2.8XALOi: o
, aχ, Fe: 1.3 Z (3) When the absorbance at a wavelength of 1.06 μm was measured in the same manner as in Example 1, it was 4 or more.

Further, when directly irradiated with a Nd-YAG laser (wavelength: 1.06 μm, beam diameter: 31 μm), cracks occurred after 100 WI minutes, but no abnormalities were observed after 50 W for 1 minute.

<Example 4> +1) Cr was added to borosilicate glass having the same composition as in Example 3 (1) to give a glass composition of 6.8% to produce a colored glass.

(2) 30% colored glass powder and 70% quartz powder were mixed, heated and melted at 2000 to 2200°C, and then poured into a mold to obtain a green filter base plate.

Both surfaces of the filter were polished to obtain a glass filter with a thickness of 3 mm. The composition of this glass filter was as follows.

5iCh: 9L, 0χ1, Na20: 2.0
χ, Ba1t: 4.2X^9-0*: 0.8
X, Cr: 2.0χ(3) wavelength 10.6μ
When the absorbance at m was measured, it was 4 or more.

In addition, C02 laser (wavelength 10.6 μm, beam diameter 3
1), an output of 50 W) was directly irradiated for 1 minute, and no abnormality was observed.

<Comparative Example 1> (1) Cr was added to borosilicate glass having the same composition as in Example 3 (1) to give a glass composition of 4.0% to produce a colored glass.

(2) 50% colored glass powder and 50% quartz powder were mixed, heated and melted at 2000 to 2200°C, and then poured into a mold to obtain a green filter original plate.

Both surfaces of the filter were polished to obtain a glass filter with a thickness of 3 mm. The composition of this glass filter was as follows.

5t02: 86.0χ, Na20; 3.4χ
, BzO! : 7.2χ89sCh : 1.4X
-Cr: 2.0 χ(3) wavelength 10.6
When the absorbance in μm was measured, it was 4 or more.

However, when it was directly irradiated with CO and a laser (wavelength: 10.6 μm, beam diameter: 3, output: 50 W), it fractured 50 seconds after irradiation.

Comparative Example 2〉 (1) A commercially available quartz glass plate with a thickness of 3 mm was coated with A by vacuum evaporation.
A g-MgF2Ag based interference reflection film (thickness: 1.06 μm) was formed.

(2) Regarding this quartz glass plate, the absorbance at a wavelength of 1.06 μm was measured in the same manner as in Example 1 and found to be 2.0.

Further, when the Nd-YAG laser was directly irradiated in the same manner as in Example 1, the reflective film was damaged in about 10 seconds. At this time, the quartz glass plate was placed so that the reflective film was on the transmission side.

<Conventional Example 1> (1) Absorbance at a wavelength of 1.06 μm was examined using a commercially available blue glass filter for laser beam safety glasses (manufactured by American Optical Co., model number 588) and was found to be 4 or more. However, Nd-YAG laser (wavelength 1.06.
crm, beam diameter 3 fins, output 15W) for 1 minute, it was destroyed even though the output was 15W.

<Conventional Example 2> (1) A laser light absorber (manufactured by Nippon Kayaku Co., Ltd., product number IRG-022) was kneaded into an acrylic resin, and a green plate material with a thickness of 3 dragons was obtained by injection molding.

(2) The absorbance at a wavelength of 1.06 μm was examined and was 4 or more.

However, when directly irradiated with the same laser (beam diameter 3x, output 10W) for 1 minute, it melted and a hole formed despite the output being IOW.

(Effects of the Invention) As explained above, the glass filter of the present invention has a laser beam absorbing component in its composition, and the 5in2 content is 90% by weight or more, so the glass filter of the present invention increases by absorption of laser beam. In addition to blocking the transmission of energetic laser light, it maintains the physical properties of quartz glass, such as high melting point and low expansion coefficient, so even if it is directly irradiated with a 50W output class laser light, the filter will not be able to pass through in a short period of time. Destruction does not occur, and the danger associated with the destruction of the filter can be reliably prevented.

As described above, the glass filter of the present invention is extremely excellent as a means for protecting against small to medium output laser beams.

Claims (3)

[Claims] (1) A glass filter having a laser beam absorption component, characterized in that the SiO_2 content is 90% by weight or more. (2) The glass filter according to claim (1), wherein a laser light reflecting film is formed on the surface of the filter. (3) The glass filter according to claim (1) or (2), wherein a photosensitive layer that causes a change in shape that can be recognized with the naked eye by laser light irradiation is formed on the entrance side surface of the filter.