JP2019139016A - Optical product, mirror, and filter - Google Patents

Abstract

To provide an optical product, and a mirror and a filter of the optical product in which the warpage of the substrate is removed with the design and the manufacturing being more simpler.SOLUTION: An optical product 1 includes: a substrate 2: an optical multilayer film 4 as a first film on a first surface 3 of the substrate 2; and a warpage correction film 6 as a second film on a second surface 5 of the substrate 2. At least one of the multilayer film 4 and the warpage correction film 6 is formed after an optical absence layer has been inserted or removed. The stress of the optical multilayer film 4 and the stress of the warpage correction film 6 are adjusted more than before the optical absence layer has been inserted or removed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical product having an optical multilayer film formed on a substrate, a total reflection mirror that substantially totally reflects a laser, a half mirror that branches the laser into two optical paths, and an oscillation wavelength that transmits excitation light. The present invention relates to a mirror such as a dichroic mirror that reflects light, and a filter such as a long wave pass filter, a short wave pass filter, and a band pass filter that transmits light in a predetermined wavelength range.

As described in Japanese Patent No. 3034668 (Patent Document 1), the equivalent refraction of a symmetric structure having substantially the same refractive index at a specific wavelength as that of the substrate on the back side of the substrate having a multilayer film deposited on the front side. There is known an interference filter in which rate film units are repeatedly laminated to have a thickness substantially equal to that of a multilayer film.
In this interference filter, when the substrate is warped due to the stress of the multilayer film on the front side surface, the equivalent refractive index film unit is repeatedly laminated on the back side surface so as to have substantially the same thickness as the multilayer film. A stress that cancels out is applied, and the warpage of the substrate is alleviated. In addition, since the refractive index of the equivalent refractive index film unit is substantially equal to the refractive index of the substrate, even if the equivalent refractive index film unit is provided, the optical characteristics at the target wavelength of the equivalent refractive index unit are affected. Absent.
In the embodiment of Japanese Patent No. 3034668, L = SiO ₂ and H = TiO ₂ constitute a unit of (L / H / L), and a dichroic filter is formed by stacking 15 units on the front side of the substrate. . Further, an equivalent refractive index unit of (L / M / L) is configured with M = Al ₂ O ₃ , and a multilayer film having a thickness substantially equal to that of the dichroic filter (multilayer film on the front side surface) is formed by repeating the stacking of 23 units. It is formed on the back side. Thus, if the dichroic filter according to the embodiment in which the warpage is mitigated is arranged in front of the liquid crystal panel in the high-definition liquid crystal vision, the generation of the condensed light or the diffused light due to the warpage is suppressed. It exhibits characteristics.

Japanese Patent No. 3034668

In the above interference filter, the repeated stacking of the equivalent refractive index units on the back side surface of the substrate alleviates the warpage of the substrate caused by the stress of the multilayer film on the front side surface, but the film thickness of the multilayer film on the front side surface is reduced. It can be adjusted only by a natural number multiple of the film thickness of the equivalent refractive index unit, and the equivalent refractive index unit is repeatedly laminated many times in order to obtain the same film thickness as a multilayer film to which an optical function is imparted. Therefore, it is difficult to design and manufacture an equivalent refractive index unit and thus an interference filter.
Therefore, a main object of the present invention is to provide an optical product in which the warpage of the substrate is removed in a simpler design and manufacture, or a mirror and a filter belonging to the optical product.

In order to achieve the above object, according to a first aspect of the present invention, there is provided an optical product, comprising: a substrate; a first film formed on the first surface of the substrate; and a second film formed on the second surface of the substrate. And at least one of the first film and the second film is formed in a state where at least one of insertion and removal of the optical absence layer is performed, and the stress of the first film The stress of the second film is adjusted so as to be more balanced than before the insertion and / or removal is performed.
The invention according to claim 2 is the above invention, wherein the first film is an optical multilayer film including a high refractive index layer and a low refractive index layer, and the second film is formed by inserting the optical absence layer and It is a warpage correction film formed in a state in which at least one of removal is performed.
According to a third aspect of the present invention, in the mirror, the first film according to the first or second aspect is a mirror film that reflects light having a wavelength λ ₀ related to the optical absence layer. It is a feature.
According to a fourth aspect of the present invention, in the above invention, the second film has an antireflection function by including a high refractive index layer and a low refractive index layer, and at least insertion and removal of the optical absence layer. It is an antireflection warpage correction film formed in a state where one of the two is made.
According to a fifth aspect of the present invention, in the filter, one of the first film and the second film in the invention has a light transmittance in a wavelength region exceeding the first predetermined wavelength, and the first predetermined wavelength is suppressed. A short wave pass filter film that transmits a relatively large amount of light in the following wavelength range, and the other is that the transmittance of light in a wavelength range equal to or less than a second predetermined wavelength that is smaller than the first predetermined wavelength is suppressed. 2. A long wave pass filter film that transmits a relatively large amount of light in a wavelength region greater than a predetermined wavelength, wherein the optical absence layer is within the second predetermined wavelength or less, or within the first predetermined wavelength or more. The wavelength λ ₀ related to is included.
The invention according to claim 6 is a short wave path filter in which the first film according to claim 1 or 2 in the above invention transmits light having a wavelength λ ₀ related to the optical absence layer. It is a film, a long wave pass filter film, or a band pass filter film.
According to a seventh aspect of the present invention, in the above invention, the second film includes a high refractive index layer and a low refractive index layer, thereby having an antireflection function, and at least insertion and removal of the optical absence layer. It is an antireflection warpage correction film formed in a state where one of the two is made.

  The main effect of the present invention is to provide an optical product in which the warpage of the substrate is removed in a simpler design and manufacture, or a mirror and a filter belonging to the optical product.

(A) is a schematic diagram in the case where only the optical multilayer film is applied to the substrate, and (b) is a warp exhibiting stress that balances with the stress of the optical multilayer film on the side opposite to the optical multilayer film in (a). It is a schematic diagram when a correction film | membrane is provided, (c) is a schematic diagram when the curvature correction film | membrane which exhibits the stress larger than the stress of an optical multilayer film is provided. It is a graph about the stress of the various films | membranes in Example 1 grade | etc.,. It is a graph about the curvature (delta) of the optical product 1 whole in Example 1 grade | etc.,. According to the reference example 4, 5 and Example 1 is a graph of the entire warp δ of the optical product 1 in the case of changing the q _L of an optical absence layer of SiO _2. It is a graph which shows the spectral reflectance distribution in the near infrared region (1020 nm or more and 1110 nm or less) which concerns on the reference example 6 and Examples 2-1 to 2-9. It is a graph which shows the spectral reflectance distribution in the near infrared region (1020 nm or more and 1110 nm or less) which concerns on the reference example 7 and Examples 3-1 to 3-13. It is a graph which shows the spectral reflectance distribution in the near infrared region (1020 nm or more and 1110 nm or less) which concerns on the reference example 8 and Examples 4-1 to 4-8. It is a graph which shows the spectral reflectance distribution in the near infrared region (1020 nm or more and 1110 nm or less) which concerns on the reference example 9 and Examples 5-1 to 5-13. It is a graph which shows the spectral transmittance distribution in the wavelength range (400 nm or more and 900 nm or less) of the visible region and infrared adjacent region which concern on the curvature correction film | membrane and optical multilayer film in the reference example 10 and Examples 6-1 to 6-5. FIG. 10 is a partially enlarged view of FIG. 9. It is a graph which shows the spectral transmittance distribution in the wavelength range (400 nm or more and 900 nm or less) of the visible region and infrared adjacent region which concern on the curvature correction film | membrane and optical multilayer film in Reference Example 10 and Examples 7-1 to 7-5. FIG. 12 is a partially enlarged view of FIG. 11. It is a graph which shows the spectral transmittance distribution in the wavelength range (900 nm or more and 1280 nm or less) of the infrared adjacent region which concerns on the curvature correction film | membrane and optical multilayer film in the reference example 11 and Examples 8-1 to 8-6.

  Hereinafter, an example of an embodiment according to the present invention will be described based on the drawings as appropriate. The embodiment of the present invention is not limited to these examples.

As shown in FIG. 1B, an optical product 1 according to the present invention includes an optical multilayer as a first film having a predetermined function formed on a substrate 2 and a front side surface (first surface 3) thereof. It has the film | membrane 4 and the curvature correction film | membrane 6 as a 2nd film | membrane.
The material of the board | substrate 2 is not specifically limited, For example, they are optical glass BK7, sapphire, quartz glass, and optical resin.
The function of the optical multilayer film 4 includes, for example, a function of branching a laser into two optical paths (half mirror), a function of transmitting laser excitation light and reflecting the laser (dichroic mirror), and a predetermined wavelength or less (or more). A function of transmitting light of a wavelength (short wave pass filter, long wave pass filter) or a function of transmitting only a predetermined wavelength range (band pass filter). The optical multilayer film 4 may have a plurality of functions by being provided with at least one of the arrangement of the antifouling layer on the outermost layer and the arrangement of the adhesion promoting layer on the layer closest to the substrate 2.

The optical multilayer film 4 is preferably an inorganic multilayer film using a dielectric material, and is an alternating film of a low refractive index layer and a high refractive index layer. The design of the optical multilayer film 4 is changed by changing the design factors such as the selection of the number and material of the high refractive index layer and the low refractive index layer, and increase / decrease of the thickness (physical film thickness or optical film thickness) of each layer. Is done.
The high refractive index layer is formed of, for example, zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), tantalum oxide (Ta ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ), hafnium oxide (HfO ₂ ), or lanthanum oxide. It is formed from a high refractive index material such as (La ₂ O ₃ ) or a mixture of two or more thereof.
The low refractive index layer is made of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), calcium fluoride (CaF ₂ ), magnesium fluoride (MgF ₂ ), or a mixture of two or more of these. It is formed from a low refractive index material.
The low refractive index layer and the high refractive index layer of the optical multilayer film 4 are formed by a vacuum vapor deposition method, an ion assist vapor deposition method, an ion plating method, a sputtering method, or the like.
By superimposing the total stress of each high refractive index layer and the total stress of each low refractive index layer, the optical multilayer film 4 has a stress as a whole and causes the substrate 2 to warp. If the optical multilayer film 4 exhibits compressive stress, the optical product 1 without tensile stress on the substrate 2 and without the warp correction film 6 described later warps to be convex toward the optical multilayer film 4 side (FIG. 1 ( a)). On the other hand, if the optical multilayer film 4 exhibits tensile stress, the substrate 2 is subjected to compressive stress, and the optical product 1 without the warp correction film 6 described later warps so as to be convex on the side opposite to the optical multilayer film 4. .

The optical product 1 according to the present invention further includes a warp correction film 6 as a second film and an optical film on the back side surface of the substrate 2 (second surface 5 symmetrical to the first surface 3).
The warp correction film 6 includes an optical absence layer.
Optical absence layer optical thickness nd (n is the refractive index, d is the film thickness) is lambda _0/2 or layer is a natural number multiple thereof. Even if an optical absence layer is inserted into a certain optical film, the optical properties of the optical film with respect to light of wavelength λ ₀ are the same as before the optical absence layer is inserted. The optical absence layer does not change the optical characteristics even if it is disposed between the optical film and the substrate 2, does not change the optical characteristics even if it is disposed on the opposite side of the substrate 2, and does not change the optical characteristics even if both are disposed. The optical characteristics are not changed even if they are arranged between the layers of the multilayer film. Hereinafter, λ ₀ may be referred to as an absent wavelength.
The optical absence layer is used, for example, to broaden the antireflection film with respect to the visible wavelength range. When an optical absence layer with a wavelength λ ₀ = 550 nm (nanometer) is inserted into the antireflection film, the reflectance with respect to the light with the wavelength λ ₀ does not change, and the reflectance on the short wavelength side and the long wavelength side thereof does not change. Can be further reduced.

Since the warp correction film 6 includes the optical absence layer, the warp correction film 6 does not affect the optical characteristics of the optical multilayer film 4 on the first surface 3 and the light having the wavelength λ ₀ of the substrate 2. Even if the warp correction film 6 is disposed, the change in the optical characteristics of light in the wavelength region adjacent to the wavelength λ ₀ is slight.
The optical absence layer also has a stress, and its magnitude is proportional to the film thickness of the optical absence layer, so that it can be adjusted by the film thickness, and is similar to the stress magnitude of the optical multilayer film 4. If the adjustment is adjusted, the warp of the substrate 2 is eliminated or alleviated, and the optical product 1 becomes flat or becomes even flatter.

The warpage correction film 6 may be a single layer film having only one layer or a multilayer film having a plurality of layers. The warp correction film 6 is preferably made of a dielectric material.
In the case of a multilayer film, the optical absence layer may be inserted in a plurality of layers. In this case, in the plurality of optical absence layers, the value of the reference wavelength λ ₀ may be different in a state of being approximate to each other.
The multilayer film is preferably an alternating film of a low refractive index layer and a high refractive index layer. The design of the warp correction film 6 is changed by changing the design factors such as the selection of the number and materials of the high refractive index layer and the low refractive index layer, and the increase or decrease in the thickness (physical film thickness or optical film thickness) of each layer. Is done. As the high refractive index material related to the high refractive index layer and the low refractive index material related to the low refractive index layer, the same material as the optical multilayer film 4 can be used.
The warp correction film 6 may have other functions in addition to the warp correction function due to the stress. For example, the warpage correction film 6 may have an antireflection function (antireflection warpage correction film). Further, the warp correction film 6 may have a function of transmitting light having a wavelength longer than or equal to a predetermined wavelength (longer) (long wave path filter warp correction film, short wave path filter warp correction film).
These films can be formed by the warp correction film 6 that is a multilayer film. The warp correction film 6 may have an optical absence layer inserted in at least any one layer after the multilayer film having the other function is designed, or optical absence in at least any one layer. The layer may be removed. In any case, the warp correction film 6 is formed so as to exhibit a stress that balances the stress (product of the film stress and the physical film thickness) of the optical multilayer film 4 on the first surface 3 as a whole. Further, in the optical multilayer film 4 on the first surface 3, the stress of the optical multilayer film 4 may be balanced with the warp correction film 6 (optical film) by inserting or removing the optical absence layer. . Alternatively, the optically absent layer is inserted or removed in both the optical multilayer film 4 on the first surface 3 and the warp correction film 6 on the second surface 5, so that the overall stress of the optical multilayer film 4 is reduced. 6 (optical film) may be balanced. Further, at least one of the optical multilayer film 4 and the warp correction film 6 (optical film) may be subjected to both insertion and removal of the optical absence layer. Further, the stress of the optical multilayer film 4 and the stress of the warp correction film 6 (optical film) do not have to be completely balanced, and are completely compared with those before at least one of insertion and removal of the optical absence layer is performed. It is sufficient that the state approaches the balance. Even in this case, the warpage of the substrate 2 or the optical product 1 is reduced.
The optical multilayer film 4 on the first surface 3 is a short wave pass filter that transmits light having a wavelength equal to or shorter than the first predetermined wavelength and suppresses transmission of light having a wavelength greater than the first predetermined wavelength. The warp correction film 6 is a long wave pass filter warp correction film that transmits light having a wavelength shorter than the first predetermined wavelength and longer than the second predetermined wavelength and suppresses transmission of light having a wavelength shorter than the second predetermined wavelength. If there is, the optical product 1 becomes a band-pass filter with a corrected warp that transmits light in a wavelength range from the second predetermined wavelength to the first predetermined wavelength. Further, even if the optical multilayer film 4 on the first surface 3 is a long wave pass filter and the warp correction film 6 on the second surface 5 is a short wave pass filter warp correction film, the optical product 1 is similarly a band pass filter. It becomes.

In the case where the optical multilayer film 4 on the first surface 3 and the warp correction film 6 on the second surface 5 are formed, both films are a high-refractive index layer related to one type of high-refractive index material and one type of low-reflection film. The warpage when the substrate 2 is a disk shape having a radius l and a plate thickness b, which are alternating films with a low refractive index layer relating to a refractive index material, will be described in further detail below.
Optical products 1 overall warping [delta], the substrate 2 alone warpage (initial warpage) and [delta] _0, warping (first warp) and [delta] ₁ caused by the deposition of the optical multilayer film 4 of the first surface 3, warpage (second warp) and [delta] ₂ caused by deposition of the warp correction layer 6 of the second surface 5, is expressed by the following [Equation 1].

The first warp δ ₁ and the second warp δ ₂ are proportional to a value obtained by multiplying the film thickness of each layer related to each film by the physical film thickness of the layer and totaling the entire multilayer film. The film stress of each layer in each film depends on the film material (high refractive index material, low refractive index material), film forming method, and film forming conditions.
Therefore, the first warp δ ₁ is set to σ _{H1 as} the film stress of the high refractive index layer related to the optical multilayer film 4 on the first surface 3, and the high refractive index layer related to the optical multilayer film 4 on the first surface 3. The total physical film thickness is d _H1 , the film stress of the low refractive index layer related to the optical multilayer film 4 on the first surface 3 is σ _L1, and each low refractive index layer related to the optical multilayer film 4 on the first surface 3 is When the total physical film thickness is d _L1 , it is proportional to (d _H1 σ _H1 + d _L1 σ _L1 ).
Further, the second warp δ ₂ is set to σ _{H2 as} the film stress of the high refractive index layer related to the warp correction film 6 of the second surface 5, and each high refractive index layer related to the warp correction film 6 of the second surface 5. The total physical film thickness is d _H2 , the film stress of the low refractive index layer related to the warp correction film 6 on the second surface 5 is σ _L2, and each low refractive index layer related to the warp correction film 6 on the second surface 5 is When the total physical film thickness is d _L2 , it is proportional to (d _H2 σ _H2 + d _L2 σ _L2 ).
Further, these proportional coefficients are 3 (1-ν _s ) l ² / E _s b ^2, where E _s is the Young's modulus of the substrate 2 and ν _s is the Poisson's ratio of the substrate 2.
Accordingly, the overall warpage δ is expressed by the following [Equation 2].

In the optical product 1 of the present invention, d _H2 , σ so that the total warpage δ caused by the optical multilayer film 4 applied to the first surface 3 in order to provide a predetermined function is as close to 0 as possible. _H2 , d _L2 , and σ _L2 are selected, and the warp correction film 6 is formed on the second surface 5.
Warpage correction film 6, so that no effect (especially in the absence wavelength lambda ₀ of the light) to a given function, are optically absent layer. Thus, the warpage correction film 6, the optical film thickness becomes discrete lambda _0/2 or its natural multiple, refractive index (refractive index of the high refractive index material n _H2, the refractive index n _L2 of the low refractive index _material) since a constant by the selection of the material, where the physical thickness _{d H2, d L2} is discrete, optical film thickness _{n H2 d H2 = λ 0/} 2, n L2 d L2 = λ 0/2 is relatively The refractive index n _H2 , n _L2 can be adjusted by selecting the material, or at least one of the radius l and the plate thickness b of the substrate 2 can be adjusted. By providing the adjusted warp correction film 6 or adjusting the substrate 2, the required accuracy can be suppressed.

The optical product 1 of the present invention preferably includes a half mirror having a function of branching a laser into two optical paths, and a dichroic mirror having a function of transmitting the laser excitation light and reflecting the laser. It is a filter that passes light such as a mirror and a laser. More preferably, the absent wavelength λ ₀ can be easily selected from the monochromaticity of the laser (λ ₀ should be the same as the wavelength of the laser), and the laser is affected. There are no laser mirrors and laser filters.

Thus, the optical product 1 of the present invention includes the substrate 2, the optical multilayer film 4 as the first film formed on the first surface 3 of the substrate 2, and the second film 5 formed on the second surface 5 of the substrate 2. A warp correction film 6 as two films, and at least one of the optical multilayer film 4 and the warp correction film 6 is formed in a state where at least one of insertion and removal of the optical absence layer is performed, The stress of the optical multilayer film 4 and the stress of the warp correction film 6 are adjusted so as to be more balanced than before the insertion and / or removal. Therefore, while providing the function that at least one of the optical multilayer film 4 and the warp correction film 6 exhibits, the warpage of the substrate 2 and thus the whole is suppressed.
The first film is an optical multilayer film 4 including a high refractive index layer and a low refractive index layer, and the second film is a warp formed with at least one of insertion and removal of an optical absence layer. This is the correction film 6. Therefore, the optical multilayer film 4 is easy to design and manufacture because at least one of insertion and removal of the optical absence layer is not performed. Further, the optical multilayer film 4 is in a state in which the warp is suppressed by the warp correction film 6, and the situation where the light to the optical multilayer film 4 is diffused or condensed is prevented.

Furthermore, the optical multilayer film 4, is a mirror film for reflecting the light of the wavelength lambda ₀ of the optical absence layer, i.e. the optical absence layers absence wavelength lambda ₀ is the same as the wavelength lambda ₀ of the reflection mirror Therefore, the optical product 1 is a mirror having a wavelength λ ₀ . Thus, a mirror with corrected warpage is provided.
The warp correction film 6 includes an antireflective function by including a high refractive index layer and a low refractive index layer, and is formed with at least one of insertion and removal of an optical absence layer. It is a correction film. Therefore, the optical absence layer does not affect the reflection of the mirror, and the warp correction film 6 corrects the mirror warp and provides an antireflection function, preventing the reflection light from diffusing and condensing, and further preventing stray light. In the case of a half mirror, dimming of transmitted light is suppressed.

In addition, one of the optical multilayer film 4 and the warp correction film 6 transmits a relatively large amount of light in the wavelength region below the first predetermined wavelength by suppressing the light transmittance in the wavelength region exceeding the first predetermined wavelength. The other is a short wave pass filter film, and the other has a reduced transmittance of light in a wavelength range not greater than the second predetermined wavelength that is smaller than the first predetermined wavelength, and relatively reduces light in the wavelength range greater than the second predetermined wavelength. The optical product 1 is a band-pass filter, and the short wave-pass filter film or the long wave-pass filter is within the second predetermined wavelength or the first predetermined wavelength. Contains the wavelength λ _{2 associated} with the optical absence layer in the film. Therefore, a bandpass filter in which the warp is appropriately corrected while the influence on the bandpass filter function is suppressed is provided.
Further, the optical multilayer film 4 is a short wave pass filter film, a long wave pass filter film or a band pass filter film that transmits light of wavelength λ ₀ related to the optical absence layer, that is, the optical absence layer is absent. The wavelength λ ₀ is included in the wavelength λ ₀ in the transmission region of the filter, and the optical product 1 is a filter related to the wavelength λ ₀ . Thus, a warp corrected filter is provided.
The warp correction film 6 includes an antireflective function by including a high refractive index layer and a low refractive index layer, and is formed with at least one of insertion and removal of an optical absence layer. It is a correction film. Therefore, the optical absence layer does not greatly affect the performance of the filter, and the warpage correction film 6 corrects the warpage of the filter and provides an antireflection function, thereby preventing the diffusion and collection of reflected light and transmitted light. Further, stray light is prevented, and dimming of transmitted light is suppressed.

Next, examples of the present invention will be described.
However, the examples do not limit the scope of the present invention. In particular, the reference wavelength λ ₀ of the optical absence layer in the embodiment is 1064 nm or 610 nm corresponding to the wavelength of a YAG (yttrium, aluminum, garnet) laser (Nd: YAG laser) to which neodymium Nd is added. 632.8 nm corresponding to the transmission region of a bandpass filter that transmits light in the wavelength region of 650 nm or less with a transmittance of approximately 100% and suppresses the wavelength region of 580 nm or less and 690 or more with a transmittance of approximately 0%. Or 632.8 nm corresponding to the wavelength of the HeNe laser (helium neon laser), the wavelength λ ₀ in the present invention is not limited to these.
Further, depending on the way of understanding the present invention, the embodiment may become a substantial comparative example that falls outside the scope of the present invention, or the comparative example may become a substantial embodiment that falls within the scope of the present invention. . Similarly, the following reference examples may be substantial examples that are within the scope of the present invention, or may be substantial comparative examples that are outside the scope of the present invention.

[Example 1]
In Example 1 of the present invention, a first surface 3 of a synthetic quartz substrate 2 having a radius l = 15 mm (millimeter) and a plate thickness b = 3 mm is formed on a first surface 3 of a wavelength λ ₀ = 632.8 nm. The optical multilayer film 4 is formed so as to be a four-layer mirror, and further, the second surface 5 of the substrate 2 is corrected by correcting the warp (first warp δ ₁ ) of the substrate 2 due to the stress of the optical multilayer film 4. The warp correction film 6 is formed so that the warpage δ is substantially zero.
In the optical multilayer film 4, the high refractive index material is Ta ₂ O ₅ and the low refractive index material is SiO ₂ , and all the 25 layers are alternately laminated with the layer closest to the substrate 2 as the low refractive index layer. It is a membrane. The optical multilayer film 4 is formed by alternately depositing a low refractive index material and a high refractive index material. The total physical film thickness of the optical multilayer film 4 is 3.9 μm (micrometer), and the product of the film stress (MPa, megapascal) and the physical film thickness as a whole is about 1580 MPa · μm. The optical multilayer film 4 is a mirror film for laser that reflects a HeNe laser with a reflectance of 99.9%. The optical multilayer film 4 exerts a compressive stress corresponding to the product of the film stress and the physical film thickness on the substrate 2 (see FIG. 1A), and the substrate 2 is optically applied before the warp correction film 6 is applied. It is warped convexly toward the multilayer film 4 side.
The warp correction film 6 is formed so as to include at least one of an optical absence layer of Ta ₂ O _{5 and} an optical absence layer of SiO ₂ with a wavelength λ ₀ = 632.8 nm. Optical thickness of the optical absence layer of Ta ₂ O ₅ is in units of optical film thickness becomes λ _0/4 (a _{H), q H H (q} H = 0,2,4, ···) next, the optical thickness of the SiO ₂ optical absence layer units of optical film thickness becomes λ _0/4 (a _{L), q L L (q} L = 0,2,4, ···) It becomes.

FIG. 2 is a graph for the stress of various films in Example 1 and the like, and FIG. 3 is a graph for the overall warp δ of the optical product 1 in Example 1 and the like.
As shown in FIG. 2, when q _H increases in the optical absence layer of Ta ₂ O ₅ related to the warp correction film 6, the physical film thickness (horizontal axis) of the optical absence layer increases, and the film stress And the product of physical film thickness (vertical axis) increase proportionally. Similarly, as q _L increases in the optically absent layer of SiO ₂ , the physical film thickness of the optically absent layer increases and the product of film stress and physical film thickness increases proportionally.
When these optically absent layers are used as elements of the warp correction film 6, the stress of the warp correction film 6 increases as shown in FIG. 2, and as shown in FIG. 3, q q = 0 when q _H = 0. _{When L} = 16, the overall corrected warpage δ (vertical axis) approaches 0, and when q _L = 18 or more, the product of the stress and film thickness of the warp correction film 6 is the product of the stress and film thickness of the optical multilayer film 4. And the correction by the warpage correction film 6 becomes excessive, and the substrate 2 becomes convex toward the warpage correction film 6 (see FIG. 1C). On the other hand, in the case of q _L = 0, the total warpage δ (vertical axis) after correction becomes almost 0 when q _H = 52, and the correction by the warpage correction film 6 becomes excessive when q _H = 54 or more (FIG. 1 ( c)).
Therefore, if the initial warpage δ ₀ = 0 (see the above [Equation 2]), the warpage correction film 6 is composed of an optically absent layer of SiO ₂ with q _H = 0 and q _L = 16. It may be made of an optically absent layer of Ta ₂ O ₅ where q _L = 0 and q _H = 52. Alternatively, the warp correction film 6 is formed so that the sum of the products of the respective stresses and film thicknesses is balanced with the product of the stress and film thicknesses of the optical multilayer film 4, and the optical absence layer of SiO _{2 and} the optical film of Ta ₂ O ₅ . It may be made up of an unattended layer. An example of such a warp correction film 6 is (q _L , q _H ) = (10, 22), (14, 10), (16, 4).

Further, in FIG. 2, as three types of reference examples, the optical multilayer film 4 is a mirror film having a reflectivity of 66%, 95%, and 99% (66% is a half mirror film) (in order of reference example 1). -3). These optical multilayer films 4 have the same film configuration as that of Example 1 except for the total number of layers and the total physical film thickness, and the total number of layers is 7, 13, 19 in this order. The physical film thickness is 1.1 μm, 2.0 μm, and 3.0 μm.
In these reference examples 1 to 3, the warp correction film 6 is formed in the same manner as in the first embodiment. For example, in the case of the reference example 1 in which the optical multilayer film 4 is a 66% half mirror film, the warpage correction film 6 brings the total warpage δ close to 0, so that (q _L , q _H ) = (0, 16), The optical absence layer of any one of (4, 2) is included. Similarly, in the case of Reference Example 2 in which the optical multilayer film 4 is a 95% mirror film, the warp correction film 6 includes an optical absence layer of (q _L , q _H ) = (8, 2). In the case of Reference Example 3 in which the multilayer film 4 is a 99% mirror film, the warp correction film 6 includes an optical absence layer of (q _L , q _H ) = (12, 4).

Furthermore, the optical reference of SiO _{2 according to two} reference examples (thickness b = 1 mm, 5 mm, sequentially referred to as Reference Examples 4 and 5) and Example 1 in which only the thickness b of the substrate 2 in Example 1 was changed. FIG. 4 shows a graph of the overall warp δ of the optical product 1 when q _L in the absent layer is changed.
In Reference Examples 4 and 5 and Example 1, when ΔL is a change in the overall warp δ of the optical product 1 when q _L is increased by 1, Δδ is the following [ Equation 3].

According to [Equation 3], Δδ decreases as the plate thickness b of the substrate 2 increases, and if the plate thickness b is adjusted to a large value, even if q _L related to the optical absence layer is discrete, The warp δ is more likely to approach 0 with higher accuracy. Therefore, the overall warpage δ is likely to approach 0 in the order of Reference Example 5, Example 1, and Reference Example 4.
Further, according to [Equation 3], as the radius l of the substrate 2 is smaller, Δδ is smaller, and if the radius l is adjusted to be smaller, even if q _L related to the optical absence layer is discrete, the whole The warp δ is more likely to approach 0 with higher accuracy.
These also apply when the warp correction film 6 includes an optically absent layer of Ta ₂ O ₅ and when these optically absent layers are used in combination.

[Examples 2-1 to 2-9]
The warp correction film 6 according to the second embodiment of the present invention has a wavelength λ ₀ = 1064 nm assuming that the optical product 1 is a mirror of an Nd: YAG laser, and has an antireflection function. The substrate 2 is made of optical glass BK7, and its refractive index is 1.52.
In such a warp correction film 6, the high refractive index layer H is made of Ta ₂ O ₅ , the low refractive index layer L is made of SiO ₂ , and the layer closest to the substrate 2 is the low refractive index layer L. An antireflection film (L / H / L) in which three layers are alternately stacked is used as a base (Reference Example 6), and this includes at least one of an optical absence layer of Ta ₂ O _{5 and} an optical absence layer of SiO _2. It is configured to be inserted as appropriate.
In Reference Example 6, the optical film thickness of the low refractive index layer L in contact with the substrate is 2, the optical film thickness of the adjacent high refractive index layer H is 2.40, and the next (outermost layer in contact with air) ) Of the low refractive index layer L is 1.28. The refractive index of the low refractive index layer L (SiO ₂ ) is 1.48, the refractive index of the high refractive index layer H (Ta ₂ O ₅ ) is 2.09, and the refractive index of air is 1.00. It is.
Therefore, the design of the optical film thickness of the warp correction film 6 can be expressed as follows in order, where i, j, and k are all integers of 0 or more. In the description of the design of the warp correction film 6, “L” is given to show that it is a low refractive index layer, “H” is given to show that it is a high refractive index layer, and so on. .
Substrate; (2 + 2i) L; (2.40 + 2j) H; (1.28 + 2k) L

Here, if (i, j, k) = (0, 0, 0), the warp correction film 6 becomes the reference example 6.
In (i, j, k) = (1, 0, 0), only the optical film thickness of the low refractive index layer L in contact with the substrate 2 is increased by 2L due to the insertion of the optically absent layer of SiO _2. (Example 2-1).
Similarly, (i, j, k) = (0, 1, 0), (0, 0, 1), (2, 0, 0), (0, 2, 0), (0, 0, 2) , (1, 1, 0), (0, 1, 1), (1, 0, 1) are warp correction films 6 in order of Examples 2-2 to 2-9.

The film stress σ _L2 of SiO ₂ is 529.2 MPa, and the film stress σ _H2 of Ta ₂ O ₅ is 243.5 MPa. Furthermore, the physical film thickness of the low refractive index layer L is proportional to the optical film thickness, and the physical film thickness of the high refractive index layer H is proportional to the optical film thickness. Therefore, the product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 6 and Examples 2-1 to 2-9 is as shown in [Table 1] below.
Therefore, according to the product of the physical film thickness and the film stress in the optical multilayer film 4 applied for the reflection of the Nd: YAG laser, Examples 2-1 to 2-9 (or other i, j, k) are used. Combination) can be selected.

Further, as shown in FIG. 5, Examples 2-1 to 2-9 are the same as Reference Example 6 because an optical absence layer is added to Reference Example 6 that exhibits antireflection performance. The single-sided reflectance (incident angle Angle Of Incidence (AOI) = 0 °) at the wavelength λ ₀ = 1064 nm is almost zero.
As in Reference Example 6 and Examples 2-1 to 2-9, when the antireflection function is provided at the wavelength λ ₀ = 1064 nm, the following stray light prevention effect is brought about in the mirror for the Nd: YAG laser.
That is, there is no optical multilayer film 4 that completely reflects the Nd: YAG laser 100%, and the optical multilayer film 4 generates a slight transmitted light of about 0.1%, for example. The transmitted light also passes through the substrate 2 and reaches the warp correction film 6. If the warp correction film 6 does not have an antireflection function, the transmitted light is reflected by the warp correction film 6 toward the substrate 2 and strays to the Nd: YAG laser side reflected by the optical multilayer film 4. (Stray light). On the other hand, since the warp correction film 6 of Reference Example 6 and Examples 2-1 to 2-9 has an antireflection function, the transmitted light is not reflected but also passes through the warp correction film 6. , It does not go to the Nd: YAG laser side and does not become stray light.
When the optical multilayer film 4 is a half mirror film for making the laser two optical paths by reflection and transmission of the laser, if the warp correction film 6 has an antireflection function, in addition to preventing stray light, The amount of transmitted light can be secured.
When the optical multilayer film 4 is a dichroic mirror film for transmitting the excitation light (wavelength 969 nm) of the Yb: YAG laser and reflecting the oscillation light (wavelength range 1020 nm or more and 1040 nm or less), the wavelength of the warp correction film 6 is If an antireflection function at 969 nm is provided, in addition to preventing stray light, it is possible to secure the transmitted light amount of excitation light.

[Examples 3-1 to 3-13]
The warpage correction film 6 according to the third embodiment of the present invention has a wavelength λ ₀ = 1064 nm assuming that the optical product 1 is a mirror of an Nd: YAG laser, and has an antireflection function. The substrate 2 is made of sapphire and its refractive index is 1.76.
In such a warp correction film 6, the high refractive index layer H is made of Ta ₂ O ₅ , the low refractive index layer L is made of SiO ₂ , and the layer closest to the substrate 2 is the high refractive index layer H. An antireflection film (H / L) in which two layers are alternately laminated is used as a base (Reference Example 7), and an optical absence layer of SiO ₂ is appropriately inserted between the substrate 2 and the high refractive index layer H. Composed.
In Reference Example 7, the optical film thickness of the high refractive index layer H in contact with the substrate 2 is 0.495H, and the optical film thickness of the low refractive index layer L adjacent to it (the outermost layer in contact with air) is 1.142L. is there.
Therefore, the optical film thickness of the warp correction film 6 can be expressed as follows in order with q being 0 or an even number.
Substrate; qL; 0.495H; 1.142L

Here, if q = 0, the warp correction film 6 becomes the reference example 7, and only in this case, the warp correction film 6 is a total of two layers in contact with the high refractive index layer H.
When q = 2, the optical film thickness of the low refractive index layer L in contact with the substrate becomes 2L due to the insertion of the optically absent layer of SiO ₂ (Example 3-1).
Similarly, the warp correction films 6 for q = 4, 6, 8, 10, 12, 14, 16, 18, 20, 30, 34, 40 are sequentially referred to as Examples 3-2 to 3-13.

The product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 7 and Examples 3-1 to 3-13 is as shown in [Table 2] below.
Therefore, according to the product of the physical film thickness and the film stress in the optical multilayer film 4 applied for the reflection of the Nd: YAG laser, the examples 3-1 to 3-13 (or other values of q) are changed. You can choose.

Further, as shown in FIG. 6, each of Examples 3-1 to 3-13 has an antireflection function because an optical absence layer is added to Reference Example 7 that exhibits antireflection performance. The single-sided reflectance (AOI = 0 °) at the wavelength λ ₀ = 1064 nm is substantially zero.
As in Reference Example 7 and Examples 3-1 to 3-13, when having an antireflection function at the wavelength λ ₀ = 1064 nm, the mirror for the Nd: YAG laser as the optical product 1 exhibits a stray light prevention effect.

[Examples 4-1 to 4-8]
The warpage correction film 6 according to the fourth embodiment of the present invention has a wavelength λ ₀ = 1064 nm, assuming that the optical product 1 is a mirror of an Nd: YAG laser, and has an antireflection function. The substrate 2 is made of sapphire and its refractive index is 1.76.
In such a warp correction film 6, the high refractive index layer H is made of Ta ₂ O ₅ , the low refractive index layer L is made of SiO ₂ , and the layer closest to the substrate 2 is the low refractive index layer L. An antireflection film in which seven layers are alternately laminated is used as a base (Reference Example 8), and an optical absence layer of SiO ₂ is appropriately inserted (removed) into a low refractive index layer L adjacent to the substrate 2. .
In Reference Example 8, the optical film thickness of the low refractive index layer L in contact with the substrate is 8.281 L, and the optical film thickness of each layer is 2.258H, 10.530L, 2.153H, 10.086L, 0 in order. 418H, 1.225L.
Accordingly, the optical film thickness of the warp correction film 6 can be expressed as follows in order, with q ′ being 0, an even number of 8 or less, or a negative even number of −8 or more.
Substrate; (8.281 + q ′) L; 2.258H; 10.530L; 2.153H; 10.086L; 0.418H; 1.225L

Here, if q ′ = − 8, the warp correction film 6 is in a state where the thickest optical absence layer is removed from the low refractive index layer L in contact with the substrate, and the optical of the low refractive index layer L in contact with the substrate is obtained. The film thickness is the thinnest (Example 4-1).
Similarly, the warp correction films 6 in which q ′ = − 6, −4, −2 are sequentially referred to as Examples 4-2 to 4-4.
Further, when q ′ = 0, the warp correction film 6 becomes the reference example 8.
Similarly, the warp correction films 6 with q ′ = 2, 4, 6, and 8 are sequentially referred to as Examples 4-5 to 4-8.

The product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 8 and Examples 4-1 to 4-8 is as shown in [Table 3] below.
Therefore, according to the product of the physical film thickness and the film stress in the optical multilayer film 4 applied for the reflection of the Nd: YAG laser, Examples 4-1 to 4-8 (or other numbers that are an even number of 10 or more) Q ′ value) can be selected.

Further, as shown in FIG. 7, Examples 4-1 to 4-8 are obtained by adding (removing) an optical absence layer to Reference Example 8 exhibiting antireflection performance. The single-sided reflectance (AOI = 0 °) at the wavelength λ ₀ = 1064 nm is substantially zero.
As in Reference Example 8 and Examples 4-1 to 4-8, when having an antireflection function at the wavelength λ ₀ = 1064 nm, the mirror for the Nd: YAG laser as the optical product 1 exhibits a stray light prevention effect.

[Examples 5-1 to 5-13]
The warpage correction film 6 according to Example 5 of the present invention has a wavelength λ ₀ = 1064 nm, assuming that the optical product 1 is a mirror (AOI = 45 °, p-polarized light) of an Nd: YAG laser. It has an antireflection function. The substrate 2 is made of sapphire and its refractive index is 1.76.
In such a warp correction film 6, the high refractive index layer H is made of Ta ₂ O ₅ , the low refractive index layer L is made of SiO ₂ , and the layer closest to the substrate 2 is the high refractive index layer H. An antireflection film (H / L) in which two layers are alternately stacked is used as a base (Reference Example 9), and an optical absence layer of SiO ₂ is appropriately inserted between the substrate 2 and the high refractive index layer H. Composed.
In Reference Example 9, the optical film thickness of the high refractive index layer H in contact with the substrate is 2.328H, and the optical film thickness of the low refractive index layer L adjacent thereto (the outermost layer in contact with air) is 1.315L. .
Therefore, the optical film thickness of the warp correction film 6 can be expressed as follows in order with q being 0 or an even number. In the fifth embodiment, it is assumed that a mirror centering on AOI = 45 ° is used, and the optical path in the warp correction film 6 of light incident on the warp correction film 6 is increased as compared with the case where AOI = 0 °. Therefore, a coefficient 1 / cos θ _L for adjusting the optical film thickness is applied. Here, θ _L = sin ⁻¹ (sin 45 ° / n _L2 ), and n _L2 is the refractive index (1.48) of the optically absent layer of the low refractive index material (SiO ₂ ) in the warp correction film 6. .
Substrate; (q / cos θ _L ) L; 2.328H; 1.315L

Here, if q = 0, the warp correction film 6 becomes the reference example 9, and only at this time, the warp correction film 6 becomes a total of two layers in contact with the high refractive index layer H.
When q = 2, the optical film thickness of the low refractive index layer L in contact with the substrate becomes 2 / cos θ _L L due to the insertion of the optically absent layer of SiO ₂ (Example 5-1).
Similarly, the warp correction films 6 with q = 4, 6, 8, 10, 12, 14, 16, 18, 20, 30, 34, 40 are sequentially designated as Examples 5-2 to 5-13.

The product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 9 and Examples 5-1 to 5-13 is as shown in [Table 4] below.
Therefore, according to the product of the physical film thickness and the film stress in the optical multilayer film 4 applied for the reflection centered on AOI = 45 ° of the Nd: YAG laser, the examples 5-1 to 5-13 ( Alternatively, other values of q) can be selected.

Further, as shown in FIG. 8, in Examples 5-1 to 5-13, an optical absence layer is added to Reference Example 9 which exhibits antireflection performance at least at a wavelength λ ₀ = 1064 nm centering on AOI = 45 °. Therefore, each has an antireflection function, and the single-sided reflectance (AOI = 45 °, p-polarized light) at the wavelength λ ₀ = 1064 nm is almost zero.
When having an antireflection function as in Reference Example 9 and Examples 5-1 to 5-13, the mirror for the Nd: YAG laser as the optical product 1 exhibits a stray light prevention effect.

[Examples 6-1 to 6-5]
The optical product 1 according to Example 6 of the present invention transmits light in the wavelength range of 610 nm to 650 nm with a transmittance of about 100% and suppresses the wavelength ranges of 580 nm or less and 690 nm or more with a transmittance of about 0%. It is a band pass filter that performs.
The substrate 2 of Example 6 is made of optical glass BK7, and its refractive index is 1.52.

The optical multilayer film 4 in Example 6 is a short wave that transmits light in a wavelength region below the first predetermined wavelength while suppressing the light transmittance in the wavelength region exceeding the first predetermined wavelength (650 nm). It is a pass filter membrane. The optical multilayer film 4 is designed at a design center wavelength λ ₁ = 770 nm.
In the optical multilayer film 4, the high refractive index layer H is made of Ta ₂ O ₅ and the low refractive index layer L is made of SiO ₂ . They are stacked alternately. The optical film thickness of each layer in the optical multilayer film 4 is as shown in [Table 5] below.

On the other hand, the warpage correction film 6 according to the sixth embodiment has a light transmittance in a wavelength region equal to or shorter than the second predetermined wavelength (610 nm), and transmits a relatively large amount of light in a wavelength region larger than the second predetermined wavelength. It also has a function as a long wave pass filter film. The warpage correction film 6 is designed at a design center wavelength λ ₂ = 545 nm.
In such a warp correction film 6, the high refractive index layer H is made of Ta ₂ O ₅ , the low refractive index layer L is made of SiO ₂ , and the layer closest to the substrate 2 is the high refractive index layer H. A film in which 32 layers are alternately stacked is used as a base (Reference Example 10). The optical film thickness of each layer in Reference Example 10 is as shown in [Table 6] below.

In the warp correction film 6, an optically absent layer of SiO ₂ having an absent wavelength λ ₀ = 632.8 nm is appropriately inserted (removed) between the high refractive index layer H adjacent to the substrate 2 and the substrate 2 in Reference Example 10. ) Is configured. The absent wavelength λ ₀ is in a range that is not less than the second predetermined wavelength and not more than the first predetermined wavelength. The optical film thickness of the optical absence layer is expressed by the following [Equation 4], where q is 0 or an even number. Here, n _L1 is the refractive index (1.486) of the low refractive index material (SiO ₂ ) of the optical multilayer film 4, and n _L2 is the refractive index of the low refractive index material (SiO ₂ ) of the warp correction film 6 ( 1.490).

Here, if q = 0, the warp correction film 6 is the reference example 10, and only at this time, the total refractive index layer H is in contact with the substrate 2 and has 32 layers.
When q = 2, the optical film thickness of the low refractive index layer L in contact with the substrate 2 is 2 {(λ ₂ / n _L2 ) / (λ ₀ / n _L1 ) due to the insertion of the optically absent layer of SiO _2. } L (Example 6-1).
Similarly, the warp correction films 6 in which q = 4, 6, 8, 10 are sequentially referred to as Examples 6-2 to 6-5.
The warp correction films 6 of Examples 6-1 to 6-5 have a total of 33 layers.

The product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 10 and Examples 6-1 to 6-5 is as shown in [Table 7] below.
Therefore, Examples 6-1 to 6-5 (or other values of q) can be selected according to the product of the physical film thickness and the film stress in the optical multilayer film 4 which is a short wave pass filter. In Example 6, since the product of the film thickness and stress in the optical multilayer film 4 is 1356.8 MPa · μm, when the initial warpage δ ₀ = 0, Example 6-3 (product of film thickness and stress = And the substrate 2 or the optical product 1 is flattened, and the reference example 10 and the examples 6-1 to 6-2 are closer to the optical multilayer film 4 side than the example 6-3. The examples 6-4 to 6-5 warp convexly toward the warp correction film 6 as compared with the example 6-3.

Further, as shown in FIGS. 9 and 10, each of Examples 6-1 to 6-5 is obtained by adding an optical absence layer to Reference Example 10 exhibiting long wave pass filter performance. A long wave pass filter function is provided, and the transmittance (AOI = 0 °) at the wavelength λ ₀ = 632.8 nm is approximately 99%. In the adjacent region of wavelength λ ₀ (610 nm or more and 650 nm or less), the transmittances of Examples 6-1 to 6-5 are maintained at about 99% as in Reference Example 10.
When the warp correction film 6 having the long wave pass filter function is combined with the optical multilayer film 4 having the short wave pass filter function as in Reference Example 10 and Examples 6-1 to 6-5, the optical product 1 becomes a band. It becomes a pass filter.

[Examples 7-1 to 7-5]
The optical product 1 according to Example 7 of the present invention is the same as Example 6 except for the insertion position of the optical absence layer.
In Example 7, the optical absence layer of the low refractive index material (SiO ₂ ) is expressed by the above [Equation 4] on the low refractive index layer L (outermost layer) on the most air side of Reference Example 10. Inserted with optical film thickness. Therefore, in Example 7, the optical film thickness of the outermost low refractive index layer L is [1.756 + q {(λ ₂ / n _L2 ) / (λ ₀ / n _L1 )}] L (the following [ (See Equation 5]).

When q = 2, the optical film thickness of the low refractive index layer L added to Reference Example 10 is 2 {(λ ₂ / n _L2 ) / (λ ₀ / by insertion of the optically absent layer of SiO _{2. nL1} )} L (Example 7-1).
Similarly, the warp correction films 6 with q = 4, 6, 8, 10 are sequentially set as Examples 7-2 to 7-5.
The warp correction film 6 of Examples 7-1 to 7-5 has a total of 32 layers as in Reference Example 10.

The product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 10 and Examples 7-1 to 7-5 is the same as that in Examples 6-1 to 6-5 in Examples 7-1 to 7-5. It becomes as shown in the above [Table 7] in the state replaced with.
Therefore, Examples 7-1 to 7-5 (or other values of q) can be selected according to the product of the physical film thickness and the film stress in the optical multilayer film 4 which is a short wave pass filter. In Example 7, since the product of the film thickness and stress in the optical multilayer film 4 is 1356.8 MPa · μm, when the initial warpage δ ₀ = 0, Example 7-3 (product of film thickness and stress = And the substrate 2 or the optical product 1 is flattened, and the reference example 10 and the examples 7-1 to 7-2 are closer to the optical multilayer film 4 side than the example 7-3. The examples 7-4 to 7-5 warp convexly toward the warp correction film 6 as compared with the example 7-3.

Further, as shown in FIGS. 11 and 12, each of Examples 7-1 to 7-5 is obtained by adding an optical absence layer to Reference Example 10 exhibiting long wave pass filter performance. A long wave pass filter function is provided, and the transmittance (AOI = 0 °) at the wavelength λ ₀ = 632.8 nm is approximately 99%. In the adjacent region (610 nm or more and 650 nm or less) of the wavelength λ ₀ , the transmittances of Examples 6-1 to 6-5 are maintained at about 97% to 99%.
When the warp correction film 6 having the long wave pass filter function is combined with the optical multilayer film 4 having the short wave pass filter function as in Reference Example 10 and Examples 7-1 to 7-5, the optical product 1 becomes a band. It becomes a pass filter.

[Examples 8-1 to 8-6]
The optical product 1 according to Example 8 of the present invention transmits light in the wavelength range of 1040 nm to 1080 nm with a transmittance of about 100%, and suppresses the wavelength range of 1020 nm or less and 1100 nm or more with a transmittance of about 0%. It is a band pass filter that performs.
The substrate 2 of Example 8 is made of optical glass BK7, and its refractive index is 1.52.

In the optical multilayer film 4 in Example 8, both the light transmittance in the wavelength region below the third predetermined wavelength (1020 nm) and the light transmittance in the wavelength region above the fourth predetermined wavelength (1100 nm) are suppressed, and This is a bandpass filter film that transmits a relatively large amount of light in a wavelength range from the third predetermined wavelength to the fourth predetermined wavelength. The optical multilayer film 4 is designed at a design center wavelength λ ₁ = 1064 nm.
In the optical multilayer film 4, the high refractive index layer H is made of Ta ₂ O ₅ and the low refractive index layer L is made of SiO ₂ . They are stacked alternately. The optical film thickness of each layer in the optical multilayer film 4 is as shown in [Table 8] below. The product of the physical film thickness and the film stress in the optical multilayer film 4 is 2094.0 MPa · μm. Note that “2.000L” of the 6th, 18th, and 30th layers from the substrate 2 side is not formed as an optical absence layer, but is designed to exhibit the characteristics of a bandpass filter. It is a thing.

On the other hand, the warp correction film 6 according to Example 8 also serves as an antireflection film. The warpage correction film 6 is designed at a design center wavelength λ ₂ = 1064 nm.
In such a warp correction film 6, the high refractive index layer H is made of Ta ₂ O ₅ , the low refractive index layer L is made of SiO ₂ , and the layer closest to the substrate 2 is the low refractive index layer L. A film in which seven layers are alternately laminated is used as a base (Reference Example 11), and optically absent layers are appropriately removed from the low refractive index layers L in the first, third and fifth layers counted from the substrate 2. Configured.
In Reference Example 11, the optical film thickness of the low refractive index layer L (first layer) in contact with the substrate is 8.021L, and the optical film thicknesses are 2.031H, 10.573L, 1.993H, and 9.649L in the following order. , 0.403H, 1.258L.
Accordingly, the optical film thickness of the warp correction film 6 can be expressed as follows in order, with i ′ and j ′ being 0 or a negative even number.
Substrate; (8.021 + i ′) L; 2.031H; (10.573 + j ′) L; 1.993H; 9.649L; 0.403H; 1.258L

Here, if (i ′, j ′) = (0, 0), the warp correction film 6 becomes the reference example 11.
Further, in (i ′, j ′) = (− 2, 0), the optical film thickness of the low refractive index layer L in contact with the substrate becomes 6.021 L by removing the optically absent layer of SiO ₂ (implementation). Example 8-1).
Similarly, the warp becomes (i ′, j ′) = (− 2, 0), (−4, 0), (−6, 0), (−6, −2), (−6, −4). The correction film 6 is set to Examples 8-2 to 8-6 in order.

The product of the physical film thickness and the film stress of the warp correction film 6 in Reference Example 11 and Examples 8-1 to 8-6 is as shown in [Table 9] below.
Therefore, Examples 8-1 to 8-6 (or other values of i ′ and j ′) are selected according to the product of the physical film thickness and the film stress in the optical multilayer film 4 that is a bandpass filter. Can do. In Example 8, since the product of the film thickness and stress in the optical multilayer film 4 is 2094.0 MPa · μm, when the initial warpage δ ₀ = 0, Examples 8-4 and 8-5 (film thickness and The product of stress = 2179.9 MPa · μm, 19899.9 MPa · μm) is selected to ensure flatness.
If the substrate 2 or the optical product 1 becomes flat, the reflected light and transmitted light of the optical product 1 are prevented from being collected or diffused, and the direction-invariant transmission of light in a predetermined wavelength range as a bandpass filter is ensured. Can be done. Further, when manufacturing a plurality of optical products 1, the optical multilayer film 4 and the warp correction film 6 are first formed on the wafer, and then the optical product 1 may be obtained by cutting the wafer. In this case, warpage of the wafer is also prevented by the warpage correction film 6. Therefore, the wafer is cut reliably and easily at a desired position as compared with the case where the wafer is warped, and the flat optical product 1 having a desired shape is subjected to the optical multilayer film 4 and the warp correction each time. A plurality of films 6 are obtained at a time by forming the film 6.

Further, as shown in FIG. 13, the examples 8-1 to 8-6 are the same as those in the reference example 11 in which the optical multilayer film 4 is a bandpass filter and the warp correction film 6 is an antireflection film. Since the optically absent layer is removed from the 6 layers, each has a band-pass filter function, and the transmittance at a wavelength λ ₀ = 1064 nm (AOI = 0 °) is almost 99%. is there. In the adjacent region of wavelength λ ₀ (from 1040 nm to 1080 nm), the transmittances of Examples 8-1 to 8-6 are maintained at about 99%, as in Reference Example 11.
When the warp correction film 6 having an antireflection function as in Reference Example 11 and Examples 8-1 to 8-6 is combined with the optical multilayer film 4 having a bandpass filter function, the optical product 1 prevents stray light. As a result, a band-pass filter in which dimming of transmitted light is suppressed is obtained.
In Reference Example 11 and Examples 8-1 to 8-6, the optical multilayer film 4 is a band pass filter. However, the optical multilayer film 4 may be a long wave pass filter instead of the band pass filter. However, it may be a short wave path filter.

In the above-described embodiment, the warp of the substrate 2 having the optical multilayer film 4 on the first surface 3 is inserted or removed from the warp correction film 6 formed on the second surface 5. Is reduced or removed, the optical absence layer is inserted or removed from the optical multilayer film 4 to reduce the warpage of the substrate 2 having the warp correction film 6 (optical film) on the second surface 5. The optically absent layer is inserted or removed in both the optical multilayer film 4 and the warp correction film 6 so that the warp of the substrate 2 (optical product 1) is reduced or removed. May be.
Further, in the warp correction film 6, the optically absent layer may be inserted or removed at a plurality of locations (for example, between the substrate 2 and on the outermost layer), and the insertion and removal of the optically absent layer are used in combination. May be. This also applies to the optical multilayer film 4.
Further, the total number of layers of the optical multilayer film 4 is not limited to those of the above-described embodiments and the like, and may be one layer (single layer film) or a larger number of layers. At least one of the low-refractive index material and the high-refractive index material in the optical multilayer film 4 is not limited to those in the above-described examples, and three or more kinds of materials may be used. The same applies to the warp correction film 6. Further, a material different from that of the optical multilayer film 4 may be used for the warp correction film 6.

  1..Optical products 2..Board 3..First surface (of substrate) 4..Multilayer film (first film) 5..Second surface (of substrate) 6..Warpage correction Membrane (second membrane).

Claims (7)

A substrate,
A first film formed on the first surface of the substrate;
A second film formed on the second surface of the substrate;
With
At least one of the first film and the second film is formed in a state where at least one of insertion and removal of the optical absence layer is performed, and the stress of the first film and the stress of the second film are An optical product characterized in that the optical product is adjusted to be more balanced than before at least one of the insertion and removal. The first film is an optical multilayer film including a high refractive index layer and a low refractive index layer,
The optical product according to claim 1, wherein the second film is a warp correction film formed in a state where at least one of insertion and removal of the optical absence layer is performed. 3. The mirror according to claim 1, wherein the first film according to claim 1 is a mirror film that reflects light having a wavelength of [lambda] ₀ related to the optical absence layer. The second film includes an antireflective function by including a high refractive index layer and a low refractive index layer, and at least one of insertion and removal of the optical absence layer is performed. 4. The mirror according to claim 3, wherein the mirror is a film. In one of the first film and the second film according to claim 1 or 2, the transmittance of light in a wavelength region exceeding a first predetermined wavelength is suppressed, and a wavelength region of the first predetermined wavelength or less is suppressed. It is a short wave pass filter film that transmits a relatively large amount of light, and the other is less than the second predetermined wavelength that is smaller than the first predetermined wavelength and has a light transmittance that is greater than the second predetermined wavelength. It is a long wave pass filter film that transmits a relatively large amount of light in the wavelength range,
Said second predetermined wavelength or less, or the in the first predetermined wavelength or range, the filter being characterized in that when the wavelength lambda ₂ is entered according to said optical absence layer in the second layer. The first film according to claim 1 or 2 is a short wave pass filter film, a long wave pass filter film, or a band pass filter film that transmits light having a wavelength λ ₀ related to the optical absence layer. A filter characterized by The second film includes an antireflective function by including a high refractive index layer and a low refractive index layer, and at least one of insertion and removal of the optical absence layer is performed. The filter according to claim 6, wherein the filter is a membrane.

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