TWI486620B - Method for manufacturing optical member and optical member - Google Patents

Description

Optical member manufacturing method and optical member

The present invention relates to a method of manufacturing an optical member and an optical member.

Conventionally, an optical member including a spherical lens is known as one of optical members such as light collected by light in the field of optical communication. In such an optical member, in order to achieve a purpose of suppressing a decrease in light transmittance due to reflection of light in the surface of the spherical lens, generally, an optical such as a reflection suppressing film is formed on the surface of the spherical lens. Sexual functional membrane.

However, the spherical lens system has a curvature much larger than that of a general lens, and thus it is difficult to form an optical functional film on the surface of the spherical lens.

In view of the above, various methods for forming an optical functional film on the surface of a spherical lens are proposed in Patent Documents 1 to 3 and the like described below.

Specifically, in Patent Document 1, it is described that a plurality of vapor deposition sources are disposed with respect to a reproducible or self-revolving component supporting mechanism, and an optical functional film having a uniform thickness is formed in a curvature supported by the component supporting mechanism. The method of large lenses.

Patent Document 2 discloses that an optical functional film having a uniform thickness is formed on the surface of the spherical lens while the spherical lens is rotated and revolved around the rotation axis that is inclined in the vertical direction. (Filter membrane).

Patent Document 3 discloses that when the film forming jig that revolves while rotating is positioned in the film formation region, the film forming material is moved toward the central portion of the spherical lens, thereby forming on the surface of the spherical lens. An optical functional film having a film thickness at a peripheral portion that is thinner than a film thickness at a central portion.

(previous technical literature) (Patent Literature)

(Patent Document 1) Japanese Patent Laid-Open No. Hei 11-106901

(Patent Document 2) Japanese Patent Laid-Open Publication No. 2006-342384

(Patent Document 3) Japanese Patent Laid-Open Publication No. 2007-108425

However, as described in Patent Documents 1 and 2, when an optical functional film having a uniform thickness is formed on the surface of the spherical lens, it may be difficult to obtain desired optical characteristics. Similarly, as described in Patent Document 3, when an optical functional film having a peripheral portion having a film thickness smaller than that of the central portion is formed on the surface of the spherical lens, it is difficult to obtain desired optical characteristics.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for producing an optical member having desired optical characteristics and an optical member having desired optical characteristics.

The method for producing an optical member according to the present invention relates to a method for producing an optical member including a spherical lens and an optical functional film formed on the surface of the spherical lens. In the method for producing an optical member according to the present invention, the optical lens is formed by a vapor phase growth method while rotating the spherical lens around the second central axis, wherein the second central axis surrounds the first central axis The central axis of rotation is inclined with respect to the first central axis.

In the present invention, "rotation" means a circular motion centering on an axis that does not pass through an object. On the other hand, "swing" refers to a circular motion centered on an axis passing through an object.

The optical properties of the optically functional film depend on the angle of incidence of light with respect to the optically functional film. In detail, the optical property of the optical functional film shifts to a short wavelength as the incident angle of light to the optical functional film becomes larger. For example, when the optical functional film is a reflection suppressing film that suppresses reflection of light in a wavelength range below a predetermined cut-off wavelength, the cutoff wavelength is short as the incident angle of light to the optical functional film becomes larger. Wavelength shift.

Furthermore, the optical properties of the optical functional film also depend on the film thickness of the optical functional film. In detail, the optical property of the optical functional film shifts to a long wavelength as the film thickness of the optical functional film becomes thicker. For example, when the optical functional film is a reflection suppressing film that suppresses reflection of light in a wavelength range below a predetermined cut-off wavelength, the cutoff wavelength shifts to a long wavelength as the film thickness of the optical functional film becomes thicker. .

In the present invention, the "thickness of the optical functional film" means the film thickness in the normal direction of the surface of the spherical lens in which the optical functional film is formed.

Here, when the collimated light or the diffused light is incident on the optical functional film formed on the surface of the spherical lens, the incident angle of the light in the portion on the optical axis of the spherical lens is 0°. On the other hand, as the optical axis away from the spherical lens, the incident angle of light becomes large.

Therefore, when the film thickness of the optical functional film is uniform, the optical property of the optical functional film in the portion away from the optical axis of the spherical lens is shorter than the optical characteristic in the portion on the optical axis of the spherical lens. Wavelength shifter. That is, when a uniform optical functional film is designed on the basis of the portion located on the optical axis of the spherical lens, and the desired optical characteristics are exhibited, the optical characteristics of the portion away from the optical axis of the spherical lens are The optical characteristics of the hope are different. As a result, it is difficult to produce an optical member having desired optical characteristics as a whole.

For example, when the optical functional film is a reflection suppressing film that suppresses reflection of light in a wavelength range below a predetermined cut-off wavelength, there is a cutoff wavelength of a reflection suppressing film in a portion away from the optical axis of the spherical lens. It is less than the wavelength of the light used, and the reflectance of the light in the portion away from the optical axis of the spherical lens becomes too high. In this case, it is difficult to fabricate an optical member having a desired light transmittance.

As described in the above Patent Document 3, when an optical functional film having a peripheral portion having a film thickness smaller than that of the central portion is formed on the surface of the spherical lens, the optical characteristics are small at an incident angle of light and the film thickness is thick. The central portion is greatly different from the peripheral portion where the incident angle of light is large and the film thickness is thin. As a result, it is more difficult to fabricate optical members of desired optical characteristics.

On the other hand, in the present invention, as described above, the optical lens is formed by a vapor phase growth method while rotating the spherical lens around the second central axis, wherein the second central axis surrounds the first center. The central axis of the shaft rotation is inclined with respect to the first central axis. Therefore, the thickest portion of the optical functional film is no longer the portion on the optical axis of the spherical lens. In the central portion of the optical functional film, the film thickness is away from the optical axis of the spherical lens. And thicker. In this case, in the central portion of the optical functional film, the variation in optical characteristics can be reduced as compared with the case where the film thickness of the optical functional film is uniform. In particular, variation in optical characteristics in a portion away from the optical axis of the spherical lens can be reduced. As a result, an optical member having desired optical characteristics can be obtained.

For example, when the optical functional film is a reflection suppressing film that suppresses reflection of light in a wavelength range below a predetermined cut-off wavelength, the cutoff wavelength in a portion away from the optical axis of the spherical lens can be prevented from becoming too short. The state of affairs. Therefore, an increase in the reflectance of light in a portion away from the optical axis of the spherical lens can be suppressed. As a result, an optical member having a desired high light transmittance can be obtained.

In addition, the "spherical lens" refers to a lens in which at least one of the light entrance and exit surfaces is spherical, and the shape of the other portions is not particularly limited to a spherical shape. The "spherical lens" also includes, for example, a spherical lens body having a light entrance and exit surface, and a flange portion or a concave portion provided in a portion other than the lens body.

In the present invention, the angle θ ₀ formed by the first central axis and the second central axis is preferably larger than 0° and equal to or less than 1/2 of the central angle θ ₁ of the region in which the optical functional film is formed. When the angle θ _{0 is} larger than 1/2 of the central angle θ ₁ , the film thickness of the portion of the optical functional film on the optical axis becomes too thin, and the desired optical characteristics are not obtained.

Further, in the present invention, the type of the vapor phase growth method is not particularly limited. For example, an optical functional film can be formed by chemical vapor deposition (CVD) or physical vapor deposition (PVD). In particular, the physical vapor phase growth method is more preferable because it forms a two-dimensional optical functional film on the surface of the spherical lens more easily than the chemical vapor growth method. In addition, the physical vapor phase growth method is also referred to as a sputtering method or a vacuum evaporation method.

The optical member of the present invention can be suitably produced by the above-described method for producing an optical member of the present invention. The optical member of the present invention includes a spherical lens and an optical functional film. An optical functional film is formed on the surface of the aforementioned spherical lens. In the optical member of the present invention, the film thickness at the central portion of the optical functional film when viewed from the extending direction of the optical axis of the spherical lens becomes thicker as it goes away from the optical axis of the spherical lens. Therefore, in the optical member of the present invention, in the central portion of the optical functional film, the variation in optical characteristics is reduced as compared with the case where the film thickness of the optical functional film is uniform. As a result, the optical member of the present invention can achieve higher optical characteristics. For example, when the optical functional film is a reflection suppressing film that suppresses reflection of light in a wavelength range below a predetermined cut-off wavelength, it is farther away from the spherical lens than when the film thickness of the optical functional film is uniform. The cutoff wavelength in the portion of the optical axis is longer. Therefore, an increase in the reflectance of light in a portion of the optical member away from the optical axis of the spherical lens can be suppressed. Therefore, a high light transmittance can be obtained.

Further, the film thickness of the outer peripheral portion of the optical functional film located outside the center portion when viewed from the extending direction of the optical axis of the spherical lens does not need to be thicker away from the optical axis of the spherical lens. That is, in the entirety of the optical functional film, the film thickness does not necessarily have to become thicker away from the optical axis of the spherical lens. The film thickness of the outer peripheral portion may also become thinner away from the optical axis of the spherical lens.

In the present invention, any portion of the central portion of the optical functional film is preferably located closer to the center of the spherical lens than the plane including the intersection of the optical axis of the spherical lens and the optical functional film and perpendicular to the optical axis. Side. This is because if there is a portion located on the opposite side of the center of the spherical lens from the intersection of the optical axis containing the spherical lens and the optical functional film and perpendicular to the optical axis, it exists in the central portion of the optical functional film. At the time, there is a case where the optical characteristics are lowered.

In the present invention, the material of the spherical lens is not particularly limited. The spherical lens may be made of, for example, glass or a resin.

The optical functional film system is not particularly limited as long as it is a film having an optical function. The optical functional film may be, for example, a reflection suppressing film that suppresses reflection of light in a predetermined wavelength range, a filter film having a wavelength selective function, an attenuating film that mainly attenuates light by absorption, and a reflective film that reflects light in a predetermined wavelength range. .

The optical functional film may be composed of a laminated film in which a low refractive index layer having a relatively low refractive index and a high refractive index layer having a relatively high refractive index are alternately laminated. The low refractive index layer can be formed by, for example, a fluorinated alkaline earth metal such as cerium oxide, aluminum oxide or calcium fluoride. On the other hand, the high refractive index layer may be formed of titanium oxide, cerium oxide, cerium oxide, cerium oxide, tungsten oxide or the like.

Hereinafter, an example of a preferred embodiment of the present invention will be described.

Fig. 1 is a schematic view showing a manufacturing apparatus of an optical member of the present embodiment. The manufacturing apparatus 1 shown in Fig. 1 is an apparatus for manufacturing the optical member of the embodiment shown in Fig. 4. Specifically, the manufacturing apparatus 1 is a film forming apparatus that performs electron beam evaporation.

As shown in Fig. 1, the manufacturing apparatus 1 is provided with a device body 10 that partitions the film forming chamber 10a. A pressure reducing mechanism 14 such as a pressure reducing pump is connected to the film forming chamber 10a. The film forming chamber 10a can be depressurized by the pressure reducing mechanism 14.

A target 13 as a supply source, an electron gun 12, and a support mechanism 20 are provided in the film forming chamber 10a. The support mechanism 20 is provided with a support tray 21. The support tray 21 is rotatably provided in the film forming chamber 10a around the first central axis C1. The lower surface 21a of the support tray 21 is formed in a dome shape.

As shown in Figs. 1 and 2, a plurality of flat support plates 22 are attached to the lower surface 21a of the support tray 21. Each of the support plates 22 is provided at a position different from the first central axis C1 of the support disk 21. Each of the support plates 22 can be rotated around the second central axis C2. The second central axis C2 is inclined with respect to the first central axis C1. In the present embodiment, the angle θ ₀ between the first central axis C1 and the second central axis C2 is 1/2 or less of the central angle θ ₁ of the region in which the optical functional film 33 is formed as shown in Fig. 4 . .

The support tray 21 and the support plate 22 are connected to the drive mechanism 11. The drive mechanism 11 rotates the support disk 21 about the first central axis C1, and relatively rotates each of the plurality of support plates 22 with respect to the support disk 21 about the second central axis C2. Therefore, each of the support plates 22 is rotated about the first central axis C1 by the drive mechanism 11, and is rotated around the second central axis C2 that is inclined with respect to the first central axis C1.

As shown in FIGS. 2 and 3, in the support plate 22, a plurality of optical member bodies 30 are mounted in a matrix shape around the second central axis C2. However, the optical member body 30 is not attached to the second central axis C2 of the support plate 22.

As shown in FIG. 3, the optical member main body 30 is provided with the holder 31 and the spherical lens 32. The holder 31 is not particularly limited as long as it can hold the spherical lens 32. The holder 31 may be composed of, for example, a tubular member made of metal or resin.

The spherical lens 32 is a spherical lens made of, for example, glass or resin. The spherical lens 32 is fixed to the holder 31. The method of fixing the spherical lens 32 to the holder 31 is not particularly limited. For example, the spherical lens 32 can be fixed to the holder 31 by a glass frit.

Next, a manufacturing method using the optical member 34 (see FIG. 4) of the above-described manufacturing apparatus 1 will be described.

First, a plurality of optical member bodies 30 are mounted on the support plate 22. Next, as shown in FIG. 2, the support plate 22 is attached to the support tray 21. Then, the film forming chamber 10a (see FIG. 1) is set as a pressure reducing environment by the pressure reducing mechanism 14, and a gas required for film formation is supplied to the film forming chamber 10a as needed from a gas supply mechanism (not shown).

Next, while the support disk 21 and the support plate 22 are driven by the drive mechanism 11, the electron gun 12 is driven to scatter particles from the target 13, whereby film formation is performed on the surface of the spherical lens 32. Therefore, the film formation on the surface of the spherical lens 32 is performed by a vapor phase growth method such as a physical vapor phase growth method while rotating the spherical lens 32 around the second central axis C2, and the second center is formed. The shaft C2 is rotated about the central axis of the first central axis C1 and is inclined with respect to the first central axis C1.

Therefore, as shown in Fig. 4, the film thickness of the outer peripheral portion 33b of the optical functional film 33 formed as described above is thinned away from the optical axis A of the spherical lens 32, and the film thickness of the central portion 33a is It becomes thicker away from the optical axis A of the spherical lens 32. Therefore, as described above, in the central portion 33a of the optical functional film 33, the variation in optical characteristics can be reduced as compared with the case where the film thickness of the optical functional film is uniform. As a result, an optical member 34 having desired optical characteristics can be obtained.

Further, any portion of the central portion 33a of the optical functional film 33 is preferably located closer to the center side of the spherical lens 32 than the plane P, wherein the plane P includes the optical axis A of the spherical lens 32 and optical properties. The intersection of the functional film 33 is perpendicular to the optical axis of the spherical lens 32. This is because if a portion located on the opposite side of the center of the spherical lens 32 from the plane P exists in the central portion 33a of the optical functional film 33, the optical characteristics may be lowered.

Further, it is preferable that the rotational angular velocity of the support disk 21 and the rotational angular velocity of the support plate 22 around the second central axis C2 are different from each other.

(Example)

According to the above manufacturing method, the optical member shown in Fig. 4 was produced with the following design parameters. Further, the film thickness of the optical functional film of the optical member was measured by a transmission type scanning microscope. The result is shown in Fig. 5. Further, in the graph shown in Fig. 5, the horizontal axis shows the incident angle of light to the optical functional film. The vertical axis shows the film thickness of the optical functional film. The light exit port of the system using a general single-mode fiber (SMF), and a refractive index Nd 1.8, the ball diameter of Φ 2.0mm spherical lens made of glass.

Further, light is incident on the central portion of the optical functional film, and a tunable laser and a power meter are used to measure the light transmittance of the optical member. Similarly, the optical transmittance was also measured for the optical member body before the formation of the optical functional film. From these results, the light transmittance of the central portion of the optical functional film can be obtained. The results are shown in Figure 7.

Membrane structure of optical functional film: film composition shown in Table 1 below

(Comparative example)

In the film formation, the optical member was produced and optically measured in the same manner as in the above-described example except that the support plate 22 was rotated around the second central axis C2 and the support disk 21 was rotated around the first central axis C1. Film thickness and light transmittance of the functional film. The results are shown in Figures 6 and 7. Further, in the graph shown in Fig. 6, the horizontal axis shows the incident angle of light to the optical functional film. The vertical axis shows the film thickness of the optical functional film. The light exit port of the system using a general single-mode fiber (SMF), and a refractive index Nd 1.8, the ball diameter of Φ 2.0mm spherical lens made of glass.

As is apparent from the results of FIGS. 5 and 7, according to the present invention, the film thickness of the central portion can be formed by performing the film formation of the optical functional film while rotating the spherical lens around the second central axis C2. The optical functional film that becomes thicker away from the optical axis A of the spherical lens, wherein the second central axis C2 is rotated about the central axis of the first central axis C1 and is inclined with respect to the first central axis C1.

Further, by making the film thickness of the central portion of the optical functional film thicker away from the optical axis A of the spherical lens, high optical characteristics can be obtained. In other words, the optical characteristics of the light incident on the film surface obliquely from the diffused light emitted from the optical fiber are shifted toward a short wavelength, but by making the film thickness thicker, the short wavelength shift portion can be corrected, and the optical axis can be obtained. The same optical properties.

1. . . Manufacturing device

10. . . Device body

10a. . . Film forming chamber

11. . . Drive mechanism

12. . . Electron gun

13. . . Target

14. . . Pressure reducing mechanism

15. . . Second guiding portion

15A. . . Through hole

20. . . Support organization

twenty one. . . Support disk

21a. . . Support surface under the disc

twenty two. . . Support board

30. . . Optical component body

31. . . Holder

32. . . Spherical lens

33. . . Optical functional film

33a. . . Central part of optical functional film

33b. . . Optical functional film outer periphery

34. . . Optical member

A. . . Optical axis

C1. . . 1st central axis

C2. . . 2nd central axis

P. . . flat

Fig. 1 is a schematic view showing an apparatus for manufacturing an optical member according to a first embodiment of the present invention.

Figure 2 is a schematic plan view of the support member.

Figure 3 is a schematic cross-sectional view of an optical member that amplifies a portion of the support plate.

Fig. 4 is a schematic cross-sectional view showing an optical member manufactured in an embodiment of the present invention.

Fig. 5 is a graph showing the film thickness of an optical functional film (a wavelength selective filter film of 1310 nm and 1490 nm, and a 48-layer film) of an example of the present invention. In the graph shown in Fig. 5, the horizontal axis indicates the incident angle of light to the optical functional film. The vertical axis indicates the film thickness of the optical functional film.

Fig. 6 is a graph showing the film thickness of an optical functional film (a wavelength selective filter film of 1310 nm and 1490 nm, and a 48-layer film) of an example of the present invention. In the graph shown in Fig. 6, the horizontal axis indicates the incident angle of light to the optical functional film. The vertical axis indicates the film thickness of the optical functional film.

Fig. 7 is a graph showing the light transmittance of the central portion of the optical functional film of the embodiment of the present invention and the light transmittance of the corresponding portion of the optical functional film of the comparative example of the present invention.

1. . . Manufacturing device

10. . . Device body

10a. . . Film forming chamber

11. . . Drive mechanism

12. . . Electron gun

13. . . Target

14. . . Pressure reducing mechanism

20. . . Support organization

twenty one. . . Support disk

21a. . . Support surface under the disc

twenty two. . . Support board

C1. . . 1st central axis

C2. . . 2nd central axis

Claims (5)

A method for producing an optical member comprising a spherical lens and an optical functional film formed on a surface of the spherical lens, wherein the spherical lens is rotated around the second central axis In the phase growth method, the optical functional film is formed on a surface of the spherical lens, wherein the second central axis is rotated about a central axis of the first central axis and inclined with respect to the first central axis; The angle θ ₀ between the central axis and the second central axis is 1/2 or less of the central angle θ ₁ of the region in which the optical functional film is formed. The method for producing an optical member according to the first aspect of the invention, wherein the optical functional film is formed by a chemical vapor phase growth method or a physical vapor phase growth method. An optical member comprising a spherical lens and an optical functional film formed on a surface of the spherical lens, wherein a central portion of the optical functional film when viewed from an extending direction of an optical axis of the spherical lens The film thickness is thickened away from the optical axis of the spherical lens; any portion of the central portion of the optical functional film is located at an intersection of the optical axis and the optical functional film and perpendicular to the optical axis The plane is closer to the center side of the aforementioned spherical lens. The optical member according to claim 3, wherein, when viewed from the extending direction of the optical axis of the spherical lens, the film thickness of the outer peripheral portion of the optical functional film located outside the central portion is away from the foregoing ball The optical axis of the lens is thinned. The optical member according to claim 3, wherein the optical functional film is a filter film having a wavelength selective function or a reflection suppressing film that suppresses reflection of light.