JP2010089130A - Method for reading-out marking of optical member, method for forming marking and marking-fitted optical glass member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for reading-out a marking where reading-out is easy even in the case a marking having reduced influence on optical performance is formed. <P>SOLUTION: In the method for reading-out a marking of an optical member, an optical member obtained, on an optical glass member, by forming a marking composed of a fluorescent glass layer in which the absolute value of a refractive index difference with the optical glass member is ≤0.1 is irradiated with ultraviolet rays so as to read-out fluorescence generated from the fluorescent glass layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a marking reading method for an optical member, a marking forming method, and an optical glass member with marking.

  For product management and design purposes, markings may be applied on parts. As a method for forming the marking, direct marking using a scanning laser is widely used. The direct marking means a method of marking a member by marking the surface of the member to be marked with a laser beam and performing laser ablation.

Other marking forming methods include, for example, laser scanning on a glass surface coated and coated with a colored paste kneaded in the paste using a metal powder and / or an inorganic pigment as a coloring source, thereby curing the paste in the laser scanning section. After the colored paste pattern is formed, the uncured colored paste excluding the laser scanning portion is removed by dissolving in an organic solvent and then baked, whereby the drawn pattern formed by baking the colored paste pattern is made of glass. A method of forming on the surface (see Patent Document 1) is disclosed.
JP 2004-351746 A

  By the way, when marking an optical member, it is necessary to suppress the scattering and reflection by the formed marking small. If the scattering or reflection is large, flare or ghost may occur even if the marking is formed outside the optical effective diameter. However, the marking that does not affect the optical performance (flare, ghost, etc.) is naturally difficult to read.

  Accordingly, the present invention provides a marking reading method and a marking forming method that can be easily read even when a marking having a small influence on optical performance is formed, and an optical glass member with marking on which the marking is formed. With the goal.

  The present invention provides an ultraviolet light on an optical member in which a marking made of a fluorescent glass layer having an absolute value of a difference in refractive index from the optical glass member of 0.1 or less at a wavelength of 587.56 nm is formed on the optical glass member. Is provided to read out the fluorescence generated from the fluorescent glass layer.

  The fluorescent glass layer is preferably formed of fluorescent glass containing at least one element selected from the group consisting of Pr, Nd, Sm, Eu, Tb, Dy, Er, Yb, and Sb.

  Moreover, it is preferable that the marking consisting of a fluorescent glass layer is obtained by the following method. That is, on the optical glass member, fluorescent glass having absorption of 0.1% / cm or more at a wavelength at which the internal transmittance of the optical glass member is 99.9% / cm or more (the optical glass is changed by changing the wavelength of light). Fluorescent glass having an absorption of 0.1% / cm or more at the selected wavelength by measuring the internal transmittance of the member and selecting a wavelength exhibiting an internal transmittance of 99.9% / cm or more. A film of the dispersion in which the film is dispersed is formed, and the marking formation region on the surface on which the film is formed is irradiated with the laser beam having the wavelength to fuse the fine particles to the optical glass member, thereby marking Is preferably formed.

  The present invention also comprises a fluorescent glass having an absorption of 0.1% / cm or more at a wavelength at which the internal transmittance of the optical glass member is 99.9% / cm or more on the optical glass member, A film of a dispersion in which fine particles having an absolute value of the refractive index difference of 0.1 or less at a wavelength of 587.56 nm are dispersed in a medium is formed, and a laser beam having a wavelength is formed on the marking forming region on the surface on which the film is formed. Is provided, and a fine particle is fused to an optical glass member. The fine particles preferably contain at least one element selected from the group consisting of Pr, Nd, Sm, Eu, Tb, Dy, Er, Yb, and Sb.

  The present invention further provides an optical glass member with marking in which marking is formed by the above-described marking forming method.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where the marking which has a small influence on optical performance is formed, the marking reading method with which reading is easy is provided. Moreover, the optical glass member with a marking which can be used for the said method, and its manufacturing method (marking formation method) are provided.

  In the following, preferred embodiments of the present invention will be described with reference to the drawings as the case may be. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

  FIG. 1 is a cross-sectional view for explaining a marking reading method according to the embodiment. The optical member 100 used in the marking reading method of the present embodiment includes a lens-shaped optical glass member 1 and a marking 10 formed on the optical glass member 1. The marking 10 is made of a fluorescent glass layer. Examples of the shape of the marking 10 include a barcode and characters. Hereinafter, the surface on which the marking 10 is formed in the optical member 100 is referred to as an upper surface, and the direction facing the upper surface is referred to as a lower surface.

  Here, the absolute value of the refractive index difference between the fluorescent glass layer forming the marking 10 and the optical glass member 1 is 0.1 or less at a wavelength of 587.56 nm (d-line). By making the refractive index difference between the fluorescent glass layer and the optical glass member 1 in such a range, the reflectance of the interface is sufficiently small over the entire visible wavelength range, so that marking is not conspicuous under visible light. be able to. That is, the influence of marking on the optical performance of the optical member can be reduced. In order to make the marking more inconspicuous, the absolute value of the difference in refractive index between the ultraviolet light cut glass layer and the optical glass member 1 is preferably 0.05 or less (more preferably 0.02 or less). . When the absolute value of the refractive index difference is 0.1 or less, reflection at the interface of visible light becomes very small, so that the presence of the marking can hardly be recognized by the naked eye, but the marking can be read by the method described later. Therefore, it is preferable in product design.

  The optical glass member 1 can be formed of, for example, a material that transmits ultraviolet light or a material that absorbs ultraviolet light. As such a material, for example, materials commercially available as optical glass such as borosilicate glass, lanthanum borate glass, and fluoride phosphate glass can be used. Specific examples include BK7 manufactured by Schott, LAC8 manufactured by HOYA, FCD1, and FC5.

  Moreover, although the example using the lens-shaped member (optical lens) was shown as the optical glass member 1 in this embodiment, as long as the effect of this embodiment is exhibited, any optical glass member can be used. Examples of such optical glass members include prisms, mirrors, optical filters, beam splitters, and polarizers.

  When reading the marking, the marking 5 is read by irradiating the ultraviolet ray 5 from the upper surface side of the optical member 100 toward the marking 10 and observing the marking 10 from the irradiation side (upper surface side of the optical member 100). be able to. The marking 10 is made of a fluorescent glass layer and emits fluorescence when irradiated with ultraviolet rays. However, the optical glass member 1 transmits or absorbs ultraviolet rays, and only the marking portion shines. Therefore, the marking can be easily read out. FIG. 2 is a photomicrograph of the optical member in which the marking portion (letter “Eu 10%”) emits light.

  At the time of marking readout, the wavelength of ultraviolet rays to be irradiated is preferably 254 to 365 nm, and more preferably 254 to 300 nm. When the wavelength of the ultraviolet light is in the vicinity of 254 nm, the reading of the marking becomes particularly easy.

  The fluorescent glass used for forming the fluorescent glass layer is preferably one that does not emit fluorescence in the visible light region of 430 to 650 nm and emits fluorescence when irradiated with ultraviolet light of 430 nm or less. Usually, since an optical member is used in a visible light region, when a marking is formed using glass that emits fluorescence in this region, the optical performance of the optical member tends to be lowered. The fluorescent glass layer is preferably formed from fluorescent glass containing at least one element selected from the group consisting of Pr, Nd, Sm, Eu, Tb, Dy, Er, Yb, and Sb. Since fluorescent glass containing such an element emits strong fluorescence when irradiated with ultraviolet rays, it is easy to read out the marking.

  The content ratio of at least one element selected from the group consisting of Pr, Nd, Sm, Eu, Tb, Dy, Er, Yb, and Sb with respect to the total amount of the fluorescent glass is 0.1 to 10% by weight. Preferably, it is 0.5 to 5 weight%.

  The elements contained in the fluorescent glass are preferably Eu and Tb from the viewpoint of high fluorescence intensity and easy reading.

  Examples of the glass suitable for use as the fluorescent glass include Lumilas-G9, Lumilas-R7, and Lumilas-B made by Sumita Optical Glass, which are commercially available as fluorescent glass.

  Next, formation of the marking on the optical glass member will be described.

  FIG. 3 is a view for explaining a preferred example of a method for forming a marking on an optical glass member. First, an optical glass member 1 made of a material that transmits or absorbs ultraviolet rays is prepared. Next, a coating material obtained by dispersing fine particles of fluorescent glass in a medium is applied on the prepared optical glass member 1 and dried to form a film 15. Then, the formed film 15 is irradiated with the laser light 9, and a part of the film 15 is heated and melted to be fixed on the optical glass member 1. Further, if the optical glass member is washed, the fixed portion of the film 15 remains on the optical glass member 1, and a marking made of fluorescent glass is formed on the optical glass member 1.

  FIG. 3 is a cross-sectional view for explaining a preferred example of a method for forming a marking on an optical glass member. For forming the marking, first, an optical glass member 1 made of a material that transmits or absorbs ultraviolet rays is prepared. Next, on the prepared optical glass member 1, a dispersion (coating material) obtained by dispersing fine particles made of fluorescent glass in a medium made of a water-soluble polymer and water is applied to remove volatile components, A film 15 is formed. Then, the formed film 15 is irradiated with laser light 9 generated from the laser device 8 to heat the film 15 in the marking formation region (region where the marking is to be formed) on the surface on which the film 15 is formed. The fine particles made of fluorescent glass contained in the film 15 are fused (melted and fixed) to the optical glass member 1.

  Although the marking is formed as described above, each fine particle made of fluorescent glass may be fused to the optical glass member 1 by irradiation with the laser light 9, or the optical glass member 1 in a state where the fine particles are fused. It may be fused. The wavelength of the laser beam 9 is a wavelength at which the internal transmittance of the optical glass member 1 is 99.9% / cm or more. At this wavelength, the fine particles made of fluorescent glass absorb 0.1% / cm or more. have.

  It is preferable to wash (wash with water) the optical glass member 1 after fusing. By cleaning, only the fused portion (that is, the marking formation region) of the film 15 remains on the optical glass member 1. In this embodiment, since water in which a water-soluble polymer is dissolved is used as a medium, the film in the portion not irradiated with the laser light 9 can be easily removed by washing (washing). On the other hand, the water-soluble polymer is burned and removed by the generated heat in the portion irradiated with the laser beam 9, and even when it is not completely removed, it is removed during washing (water washing).

  As described above, an optical member 100 (an optical glass member with marking) in which a marking 10 (a fused product of fine particles made of fluorescent glass) is formed on the optical glass member 1 is obtained. In addition, the scanning of the laser beam 9 can be changed to a barcode shape and a character shape by changing the shape of the marking 10 to a barcode shape and a character shape, respectively.

  FIG. 4 is a cross-sectional view of a glass member with marking obtained by such a marking forming method. An optical glass member with marking 100 shown in FIG. 4 includes an optical glass member 1 and a marking 10 (a fused product of fine particles made of fluorescent glass) formed thereon. The shape of the marking 10 includes a barcode shape and a character shape as described above.

  The fine particles made of fluorescent glass can be produced, for example, by pulverizing fluorescent glass as described above. The average particle diameter of the fluorescent glass fine particles is usually 1 to 10 μm, but is preferably about 1 μm from the viewpoint of reducing surface scattering and increasing invisibility other than at the time of reading.

  A medium that can be washed away by washing is preferred. The cleaning method is not particularly limited and may be appropriately selected depending on the mechanical strength of the optical member. Examples of the cleaning method include ultrasonic cleaning, immersion cleaning, and jet cleaning.

  Examples of the medium include water; alcohols such as methanol and ethanol. From the viewpoint of moldability such as control of the coating thickness of the coating layer, the medium preferably contains a binder polymer and a solvent capable of dissolving, swelling or dispersing the binder polymer. Examples of the binder polymer include polyvinyl alcohol (PVA) and polyvinylidene fluoride (PVDF), and examples of the solvent include water; alcohols such as methanol and ethanol.

  From the viewpoint of simplifying the process, it is preferable that the medium can be washed with water. From such a viewpoint, it is preferable that the binder polymer contained in the medium is a water-soluble polymer and the solvent is water. Examples of the water-soluble polymer include starch, gelatin, cellulose derivatives (carboxymethylcellulose, methylcellulose, etc.), polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyethylene oxide, and the like. Since a thing is obtained, polyvinyl alcohol (PVA) is preferable. In addition, since PVA is normally decomposed | disassembled and volatilized at 700 degreeC or more, it does not remain as a residue after laser scanning. This is also suitable for use as a binder polymer.

  The content of the binder polymer with respect to the total weight of the dispersion in which fine particles made of fluorescent glass are dispersed in a medium is preferably 1 to 10% by weight, and more preferably 1 to 5% by weight.

  When an aqueous solution in which polyvinyl alcohol is dissolved in water is used as a medium, the content of polyvinyl alcohol with respect to the total amount of the polyvinyl alcohol aqueous solution is preferably 1 to 10% by weight, and more preferably 1 to 5% by weight. preferable. By setting the polyvinyl alcohol to such a content, the film 15 can be easily formed on the optical glass 1. In addition, the cleaning residue during cleaning can be reduced.

  Although there is no restriction | limiting in particular in the coating method on the optical glass member 1 of a coating material, For example, spraying with an air brush, application | coating using a brush, a stamp, etc., dip coating, and spin coating are mentioned. Moreover, it is preferable that application | coating shall make the thickness after drying, ie, the thickness of the membrane | film | coat 15, become 5-50 micrometers. The thickness of the film 15 is particularly preferably 5 to 20 μm. If the thickness of the film 15 is larger than 50 μm, it tends to be difficult to print with a laser beam, and if it is smaller than 5 μm, the marking tends to be difficult to read.

Examples of the laser light 9 used for melting and fixing the film 15 include a YAG laser, a YVO ₄ laser, and a CO ₂ laser. The wavelength for laser irradiation is preferably the fundamental wavelength (1060 nm), second harmonic (530 nm), or third harmonic (353 nm) of the YAG laser and YVO ₄ laser.

  Moreover, the fluorescent glass used for the coating material is 0.1% / cm or more (preferably 0.5 to 1% / cm) at a wavelength at which the internal transmittance of the optical glass member 1 is 99.9% / cm or more. It is preferable to use a glass having a light absorption of 9 mm / cm or more (preferably 99.95% or more, more preferably, the internal transmittance of the optical glass member 1 is 99.9% / cm or more. Is preferably 99.99% or more).

  Since the coating film 15 formed from such a coating material using glass has a slight absorption at the above-mentioned laser wavelength, when the laser having the above-mentioned wavelength is irradiated, it absorbs the laser beam and generates heat. The film 15 is melted by generating heat and is fixed to the surface of the optical glass member 1. On the other hand, since the laser beam is hardly absorbed by the optical glass member 1, it is possible to form a marking having a desired shape on the optical glass member 1 while preventing generation of cracks in the optical glass member.

  In addition, it is preferable that the glass used for the coating material and the glass used for the optical glass member 1 have close compositions and glass transition temperatures. Glasses having similar compositions and glass transition temperatures are likely to stick to each other.

  When marking is formed on an optical glass member by such a method, the occurrence of cracks in the optical glass member can be reduced as compared with the case where marking is formed by direct marking, and a fine marking can also be formed. It becomes possible.

  Direct marking is usually a technique in which a colored plastic member or metal surface is scanned with a laser beam and laser ablated for drawing. However, when marking a brittle material such as optical glass, there is a problem in that cracks occur when the absorption at the wavelength of the laser is increased. On the other hand, if the absorption at the wavelength of the laser is reduced, ablation itself becomes difficult.

When direct marking is performed on optical glass using the fundamental wavelength (1060 nm) and its second harmonic (530 nm) of YAG laser or YVO ₄ laser, ablation of the optical glass itself is difficult. At the third harmonic (353 nm), ablation is possible, but cracks are inevitable. Ablation is possible by using a carbon dioxide laser in the infrared region, which is the absorption wavelength region of glass, but since the wavelength is as long as about 10.6 μm, it is difficult to make fine markings of mm size or less.

  Further, as a marking forming method other than the above-described method, for example, (I) a laser drawing method of converging a laser beam inside an object and performing laser scanning to mark the inside without damaging the surface, II) A method of drawing by selectively making the inside of the transparent substrate opaque by laser scanning so as to focus on the inside of the transparent substrate, and (III) a laser beam in a wavelength region that transmits the drawing object, and fθ glass member A method of drawing by condensing the inside of an object using a laser and scanning with a laser, and (IV) applying a metal paste such as a silver paste on the glass surface and scanning the laser to cure the paste and drawing Examples thereof include a method of forming a pattern. However, when these methods are used for optical glass members, there are problems as described below.

  According to the method (I), when the object is glass, if the laser beam is focused inside, cracks may occur and reach the surface, which makes the object brittle.

  According to the method (II), although drawing can be performed inside the glass, the focusing position of the laser beam cannot be strictly controlled in the depth direction of the material, so that it is not suitable for drawing a thin transparent material. In addition, since the drawing method is based on generation of cracks in the glass due to laser scanning, there is a problem that scattering is too large.

  According to the method (III), it is possible to draw inside the glass. However, since the drawing method is based on the generation of cracks in the glass due to the scanning of the laser beam, there is a problem that the scattering is too large as in the method (II).

  According to the method (IV), free drawing is possible without causing cracks in the glass, but the marks of the metal material are greatly reflected and scattered, and when applied to optical parts, the optical performance is adversely affected. . Furthermore, firing is necessary to fix the metal paste to the glass. Therefore, it is difficult to apply to an optical component that requires a precise shape.

  However, according to the present invention, the problems of the above methods (I) to (IV) can be solved, and the marking can be easily read even when the marking having a small influence on the optical performance is formed. An attached optical glass member and a manufacturing method thereof (marking forming method) can be provided. Moreover, it becomes possible to provide the marking reading method which has the characteristics mentioned above by such an optical glass member with a marking.

  As described above, the preferable example of the marking reading method and the marking forming method according to the present embodiment has been described. However, the present invention is not limited to this.

Example 1
(Production of coating material)
Schott BK7 was prepared as a raw glass. The prepared raw glass (BK7) was pulverized to an average particle size of about 1 μm. 95 g of the pulverized powder was weighed. Then, the powder body, the addition of _Eu 2 _{O 3} powder was thoroughly stirred. The addition amount of Eu ₂ O ₃ powder, to the powder material and _Eu 2 _{O 3} the total amount of powder was 3% by weight. Further, a powder body to which Eu ₂ O ₃ powder was added was placed in a platinum crucible, dissolved at 1400 ° C. for 30 minutes, stirred and clarified, then cast on a metal mold heated to 400 ° C. and solidified. And it annealed after that and obtained fluorescent glass. This glass emits orange (wavelength near 600 nm) fluorescence with ultraviolet light having a wavelength of 400 nm or less.

  The fluorescent glass produced as described above was finely pulverized to an average particle size of about 1 μm to obtain fluorescent glass powder. Furthermore, 1 g of pure water and 1 g of a polyvinyl alcohol 10 wt% aqueous solution (manufactured by Wako Pure Chemical Industries) were mixed with 1 g of fluorescent glass powder to prepare a coating material (glass paste).

(Formation of markings on optical glass members)
An optical lens was prepared as an optical glass member. The coating material produced as described above was sprayed onto the optical lens using an air brush to form a coating material layer having a thickness of about 50 μm.

Thereafter, the coating material layer was dried to form a coating layer, and then the glass was melted and fixed on the surface of the optical member using a scanning laser as shown in FIG. The laser used was a laser marker using a second harmonic of YVO ₄ laser (Miyachi Technos, ML-9001A, wavelength 530 nm) as a light source. Such a laser can print small characters and barcodes of 1 mm or less.

  A laser was oscillated and scanned at a position of 1 mm from the outer periphery of the optical lens so that a character with a height of 0.5 mm was formed. The conditions were a current of 23 A, a frequency of 20 kHz, and a scanning speed of 100 mm / s. Thus, a part of the coating layer was melted and fixed to the optical lens surface. A small and inconspicuous marking was formed at the interface. At this wavelength, the internal transmittance of the optical glass member (optical lens) was 99.9% / cm or more, and the absorption of the fluorescent glass was 0.5% / cm.

  After the laser scanning, the unscanned coating layer adhering to the optical lens surface was washed with water. Washing was performed by a method in which an optical lens with a part of the coating layer fixed was placed in a water tank, washed with an ultrasonic cleaner, and then washed with pure water. After washing, the optical member was dried and dried. As described above, the marking made of the fluorescent glass layer was formed only on the laser scanning portion on the optical lens.

  In the produced optical member, the refractive indexes of the fluorescent glass layer and the optical lens at a wavelength of 587.56 nm were 1.53 and 1.51, respectively. That is, the refractive index difference between the fluorescent glass layer and the optical lens was 0.02 at a wavelength of 587.56 nm. Note that the fluorescent glass layer was hardly noticeable under visible light. Furthermore, both reflection and scattering were of a level that did not adversely affect the optical performance of the optical member.

(Reading of marking)
The ultraviolet light with a wavelength of 254 nm was irradiated from the upper surface of the produced optical member, and the marking was observed by the method shown in FIG. The marking emitted orange fluorescence around 600 nm, and the characters were clearly visible.

(Example 2)
(Production of coating material)

  A glass raw material powder of metal oxide or metal carbonate was prepared with the following composition disclosed in "Glass Engineering Handbook (Asakura Shoten)".

SiO ₂ : 4.0% by weight;
B ₂ O ₃ : 32.7% by weight;
CaO: 11.0% by weight;
PbO: 15.8% by weight;
La ₂ O ₃ : 29.0% by weight;
ZrO ₂ : 7.5% by weight;
As ₂ O ₃ : 0.2% by weight;

Then, the glass material powder body was prepared, by adding Pr ₂ O ₃ powder was thoroughly stirred. Amount of Pr ₂ O ₃ powder, the total amount of the powder body and _Pr 2 _{O 3} powder, and 0.5 wt%. Further, the powder body to which Pr ₂ O ₃ powder was added was placed in a platinum crucible, dissolved at 1350 ° C. for 30 minutes, stirred and clarified, then cast on a metal mold heated to 400 ° C. and solidified. And it annealed after that and obtained fluorescent glass.

  The fluorescent glass thus produced was finely pulverized to an average particle size of about 1 μm to obtain fluorescent glass powder. Furthermore, 1 g of pure water and 1 g of a polyvinyl alcohol 10 wt% aqueous solution (manufactured by Wako Pure Chemical Industries) were mixed with 1 g of fluorescent glass powder to prepare a coating material (glass paste).

(Formation of markings on optical glass members)
As an optical glass member, an optical lens made of Schott LAF2 (refractive index 1.744) was prepared. The produced coating material was sprayed onto the optical lens using an air brush to form a coating material layer having a thickness of about 50 μm.

  Furthermore, an optical member with a marking formed thereon was produced in the same manner as in Example 1. In the produced optical member, the refractive indexes of the fluorescent glass layer and the optical lens at a wavelength of 587.56 nm were 1.76 and 1.744, respectively. That is, the refractive index difference between the fluorescent glass layer and the optical lens was 0.016 at a wavelength of 587.56 nm. Note that the fluorescent glass layer was hardly noticeable under visible light. Furthermore, both reflection and scattering were of a level that did not adversely affect the optical performance of the optical member.

  In addition, in the laser wavelength with which the coating layer was irradiated, the internal transmittance of the optical glass member was 99.9% / cm or more, and the absorption of the glass used for the fluorescent glass layer was 0.5% / cm.

(Reading of marking)
The ultraviolet light with a wavelength of 254 nm was irradiated from the upper surface of the produced optical member, and the marking was observed by the method shown in FIG. The marking emitted orange fluorescence around 600 nm, and the characters were clearly visible.

It is sectional drawing for demonstrating the marking reading method which concerns on embodiment. It is a microscope picture of the optical member in which the marking part is light-emitting. It is a figure for demonstrating a suitable example of the formation method of the marking on an optical lens. It is sectional drawing of the optical glass member with a marking which concerns on embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical glass member, 8 ... Laser apparatus, 9 ... Laser beam, 10 ... Marking, 15 ... Film | membrane, 100 ... Optical member.

Claims (6)

On the optical glass member, an optical member in which a marking made of a fluorescent glass layer having an absolute value of a difference in refractive index from the optical glass member of 0.1 or less at a wavelength of 587.56 nm is formed,
An optical member marking readout method of irradiating ultraviolet light to read out fluorescence generated from the fluorescent glass layer.   The said fluorescent glass layer is formed from the said fluorescent glass containing the at least 1 sort (s) of element chosen from the group which consists of Pr, Nd, Sm, Eu, Tb, Dy, Er, Yb, and Sb. Marking reading method. On the optical glass member,
Forming a film of a dispersion in which fine particles made of fluorescent glass having an absorption of 0.1% / cm or more at a wavelength at which the internal transmittance of the optical glass member is 99.9% / cm or more are dispersed in a medium;
The marking according to claim 1, wherein the marking is formed by irradiating a laser beam having the wavelength to the marking forming region on the surface on which the film is formed to fuse the fine particles to the optical glass member. Reading method. On the optical glass member,
The optical glass member is made of fluorescent glass having an absorption of 0.1% / cm or more at a wavelength at which the internal transmittance of the optical glass member is 99.9% / cm or more, and the absolute value of the difference in refractive index from the optical glass member is the wavelength. Forming a dispersion film in which fine particles of 0.1 or less at 587.56 nm are dispersed in a medium;
A marking forming method for an optical member, wherein a laser beam having the wavelength is irradiated to a marking forming region on a surface on which the film is formed to fuse the fine particles to the optical glass member.   The marking forming method according to claim 4, wherein the fine particles contain at least one element selected from the group consisting of Pr, Nd, Sm, Eu, Tb, Dy, Er, Yb, and Sb.   An optical glass member with a marking, wherein a marking is formed by the marking forming method according to claim 4 or 5.