JP2005165249A - Antireflection film, optical lens equipped therewith and optical lens unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical lens having high transmittance and equipped with an antireflection film constituted of a comparatively small number of films thereby be nearly free from a manufacture error, and excellent in a visible region, and to provide a high-grade optical lens unit constituted of such an optical lens, having excellent color balance and high transmittance. <P>SOLUTION: The optical lens A is formed by layering the antireflection film 2 on a lens (base material) 1 having a thickness of its surface top of 1mm and a refractive index of 1.44. In the film 2, the first layer and the third layer counted from the lens 1 are set as a low refractive index layer 3 composed of low refractive index material whose refractive index is relatively low, for example, SiO<SB>2</SB>, the second layer is set as a middle refractive index layer 5 composed of middle refractive index material whose refractive index is higher than the low refractive index material and lower than high refractive index material, for example, Al<SB>2</SB>O<SB>3</SB>, and the fourth layer is set as a high refractive index layer 6 composed of the high refractive index material whose refractive index is relatively high, for example, ZrO<SB>2</SB>, and then the fifth layer is the low refractive index layer 7 composed of, for example, MgF<SB>2</SB>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an antireflection film applied to an optical lens used in the visible range, an optical lens formed on the surface thereof, and an optical lens unit including the optical lens.

  In general, an antireflection film is provided on the surface of an optical component such as a lens or a prism. Its main purpose is to improve the light transmittance and visibility of the image by improving the transmittance of the optical lens unit composed of a large number of optical components, especially by suppressing reflection in the visible range. That is. Many conventional optical devices and optical components used therein have been provided with an antireflection film in order to reduce the reflectance in the visible range. As an antireflection film, an antireflection film obtained by combining a single layer to three layers having a film thickness of λ / 4 or λ / 2 is a well-known technique.

Recently, with the advancement of optical equipment and film design technology, the required specifications of optical components and antireflection films applied to them have become higher. Such an antireflection film often has a film structure in which a large number of very thick films or very thin films are stacked.
Therefore, the antireflection film is formed on the substrate by a vacuum deposition method, a sputtering method, an ion assist method, an ion plating method or the like. In general, the antireflection band of the antireflection film can be widened by increasing the number of antireflection films from a single layer to two or more layers.
As such an antireflection film, a film composed of seven layers and having a reflectance of about 0.1 to 0.5% with respect to a wavelength range of 400 nm to 700 nm has been proposed (for example, see Patent Document 1).
Japanese Patent Laid-Open No. 10-20102

However, the film thickness of an antireflection film is controlled by an optical film thickness monitor or a crystal oscillator film thickness monitor. Therefore, the film thickness detection sensitivity and accuracy, and a predetermined film thickness are detected. Due to factors such as a time lag from when the film forming apparatus is controlled to the film forming apparatus, the actually formed film includes a manufacturing error of several nanometers in physical thickness. Therefore, as the number of antireflection films increases, the film structure tends to include a thin layer. An antireflection film having a film structure including a thin film layer is relatively more susceptible to manufacturing errors than an antireflection film having a film structure not including a thin film layer.
In addition, since the loss of light intensity increases synergistically when the number of reflection surfaces of the optical device increases, the transmittance of the entire system is about 82% in the conventional antireflection film when the optical system has 40 reflection surfaces. However, there is still a problem that adversely affects the brightness and visibility of the observation image. In particular, when there is such a variation in transmittance in the visible region, there is a problem that color reproducibility deteriorates when the color balance is lost on the observation side and the observation image is reddish or bluish.

  The present invention has been made in view of the above circumstances, and an optical lens having a high transmittance provided with an antireflection film having an excellent antireflection film in the visible region, which is less prone to manufacturing errors with a relatively small film configuration. It is an object of the present invention to provide an advanced optical lens unit that includes such an optical lens and has a good color balance and high transmittance.

The present invention employs the following means in order to solve the above problems.
The antireflective film according to the present invention is an antireflective film provided on a base material, and is made of a low refractive index material having a relatively low refractive index of the first, third, and fifth layers counted from the base material. The high refractive index layer is a high refractive index layer made of a high refractive index material having a relatively high refractive index of the fourth layer, and the high refractive index material of the second layer is higher than the low refractive index material. And an optical film thickness of the first layer is 0.15 × λ / 4 or more with respect to the design wavelength λ, 2.2 × λ / 4 or less, and the optical thickness of the second layer is 0.1 × λ / 4 or more and 0.8 × λ / 4 or less with respect to the design wavelength λ, and the optical thickness of the third layer is Is 0.1 × λ / 4 or more and 0.38 × λ / 4 or less with respect to the design wavelength λ, and the optical film thickness of the fourth layer is 1.8 × λ / 4 with respect to the design wavelength λ. 2.2 Is a lambda / 4 or less, wherein the optical thickness of the five layers design wavelength lambda against 0.8 × λ / 4 or more, characterized in that there is a 1.2 × λ / 4 or less.

  Further, the antireflection film according to the present invention is the antireflection film, and is an antireflection film provided on the base material, and the refractive indexes of the second and fifth layers relative to the base material are relatively The low refractive index layer is made of a low low refractive index material, the high refractive index layer is made of a high refractive index material having a relatively high refractive index of the fourth layer, and the refractive index of the first and third layers is the low refractive index layer. An intermediate refractive index layer made of an intermediate refractive index material that is higher than the refractive index material and lower than the high refractive index material, and the optical film thickness of the first layer is 0.3 × λ with respect to the design wavelength λ. / 4 or more and 1.8 × λ / 4 or less, and the optical film thickness of the second layer is 0.12 × λ / 4 or more and 0.60 × λ / 4 or less with respect to the design wavelength λ. The optical thickness of the third layer is 0.7 × λ / 4 or more and 1.8 × λ / 4 or less with respect to the design wavelength λ, and the optical thickness of the fourth layer is the design wavelength λ. In 1.8 × λ / 4 or more and 2.2 × λ / 4 or less, and the optical thickness of the fifth layer is 0.8 × λ / 4 or more with respect to the design wavelength λ, 1.2 Xλ / 4 or less.

  This antireflection film has a relatively small number of layers of 5 layers, and the first layer to the third layer are low refractive index layers or intermediate refractive index layers. A high antireflection effect can be obtained by reducing coloring in In addition, it is not necessary to include a relatively thin layer that is easily affected by manufacturing errors, and a stable film formation with less errors can be realized.

The antireflection film according to the present invention is the antireflection film, wherein the low refractive index layer has a refractive index in the wavelength range of 350 nm to 800 nm of 1.3 to less than 1.5, and the intermediate refractive index The refractive index in the wavelength range of 350 nm to 800 nm of the layer is 1.5 or more and less than 1.85, and the refractive index in the wavelength range of 350 nm to 800 nm of the high refractive index layer is 1.85 or more and less than 2.7. It is characterized by being.
This antireflection film can obtain a high antireflection effect in the visible range, and since the refractive index of each layer is within a certain range, various materials having a refractive index within this range can be used, A material can be selected from a wide range.

The antireflection film according to the present invention is the antireflection film, wherein the high refractive index material is CeO ₂ , Cr ₂ O ₃ , In ₂ O ₃ , SnO ₂ , ZnS, WO ₃ , TiOx (0 ≦ x ≦ 2), containing at least one of HfO ₂ , ZrO ₂ , Ta ₂ O ₅ , Y ₂ O ₃ , Pr ₆ O ₁₁ , Nb ₂ O ₅ , La ₂ O ₃ , and lanthanum titanate. Features.
The antireflection film according to the present invention is the antireflection film, wherein the intermediate refractive material includes at least one of SiO, Al ₂ O ₃ , CeF ₃ , LaF ₃ , and MgO. And
The antireflection film according to the present invention is the antireflection film, wherein the low-refractive material includes at least one of Na ₃ AlF ₆ , SiO ₂ , and MgF ₂ .
This antireflection film can obtain a high antireflection effect in the visible range, and by selecting an appropriate material from the above, an antireflection film that makes use of the characteristics of the material can be obtained.

The optical lens according to the present invention is characterized in that the substrate is a lens and the antireflection film according to the present invention is provided.
The optical lens according to the present invention is the optical lens, wherein the reflectance of the antireflection film is 0.2% or less in a wavelength range of 420 nm to 660 nm.
This optical lens can obtain a high transmittance in the visible range such as a wavelength range of 420 nm to 660 nm.

The optical lens unit according to the present invention is an optical lens unit including a plurality of optical lenses, and includes at least one optical lens according to the present invention.
Further, the optical lens unit according to the present invention is the optical lens unit, wherein a transmittance when the optical lens is connected to 1 to 40 surfaces in a wavelength range of 430 nm to 650 nm is 95% or more. And
Further, the optical lens unit according to the present invention is the optical lens unit, wherein the transmittance when the optical lens is connected to 1 to 80 surfaces in a wavelength range of 430 nm to 650 nm is 90% or more. And
This optical lens unit can obtain a high transmittance in the visible range when used in an optical apparatus used in a wavelength range of 430 nm to 650 nm.

  According to the antireflection film of the present invention, a high transmittance in the visible region can be favorably obtained at low cost. Further, according to the optical lens of the present invention, the loss of light amount in the visible range can be reduced, and a high transmittance can be obtained by a good antireflection effect. Furthermore, the optical lens unit of the present invention can ensure a sufficiently bright image when observing an object, and can obtain an observation image with good color balance without coloring.

A first embodiment according to the present invention will be described with reference to FIGS. 1 and 2 and Table 1. FIG.
The optical lens A according to this embodiment is made of S-FPL53 manufactured by OHARA INC., And an antireflection film 2 is formed on a lens (base material) 1 having a top thickness of 1 mm and a refractive index of 1.44. Laminated and provided. The antireflection film 2 is a low refractive index layer 3 made of, for example, SiO ₂ , which is a low refractive index material having a relatively low refractive index of the first layer and the third layer counted from the lens 1. Is an intermediate refractive index layer 5 made of, for example, Al ₂ O ₃ , which is higher than the low refractive index material and lower than the high refractive index material, and the refractive index of the fourth layer is relatively The high refractive index layer 6 is made of, for example, ZrO ₂ , and the fifth layer is provided with the low refractive index layer 7 made of, for example, MgF ₂ .

In addition, the optical thickness of the first layer is set to 0.15 × λ / 4 or more and 2.2 × λ / 4 or less with respect to the design wavelength λ, and the optical thickness of the second layer is set to the design wavelength λ. In contrast, the optical thickness of the third layer is 0.1 × λ / 4 or more and 0.38 × with respect to the design wavelength λ. The optical thickness of the fourth layer is set to 1.8 × λ / 4 or more and 2.2 × λ / 4 or less with respect to the design wavelength λ, and the optical thickness of the fifth layer is set to λ / 4 or less. Is 0.8 × λ / 4 or more and 1.2 × λ / 4 or less with respect to the design wavelength λ. When the design wavelength is 520 nm, Table 1 shows the refractive index in the wavelength range of 350 nm to 800 nm of the material constituting each layer, and the optical film thickness nd (n is the refractive index, d is the physical film thickness) at this time. ).
In addition, an optical lens B in which an antireflection film 2 is laminated on a lens made of S-BSL7 manufactured by OHARA INC. And having a top thickness of 1 mm and a refractive index of 1.52, and OHARA INC. An optical lens C was produced in which an antireflection film 2 was laminated on a lens made of S-BAL35 and having a surface top thickness of 1 mm and a refractive index of 1.59.

Next, a method for manufacturing optical lenses A, B, and C, and actions and effects will be described below.
The antireflection film 2 is formed by vacuum deposition in a vacuum region of 10 ⁻² to 10 ⁻⁵ Pa.
Note that an antireflection film having equivalent characteristics can also be obtained by sputtering, ion plating, or ion-assisted vapor deposition.
Further, ZrO _{2 is} used as the high refractive index material, Al ₂ O _{3 is} used as the intermediate refractive index material, and SiO ₂ and MgF ₂ are used as the low refractive index material. However, the present invention is not limited thereto. _{, CeO 2, Cr 2 O 3} , In 2 O 3, SnO 2, ZnS, WO 3, TiOx (0 ≦ x ≦ 2), HfO 2, ZrO 2, Ta 2 O 5, Y 2 O 3, Pr 6 O ₁₁ , Nb ₂ O ₅ , La ₂ O ₃ , lanthanum titanate, a mixture or a compound thereof, any one of SiO, Al ₂ O ₃ , CeF ₃ , LaF ₃ , MgO as an intermediate refractive index material, or these mixtures or compounds, _Na 3 _AlF 6 as a low refractive index _material, SiO 2, one of MgF _2, or so on these mixtures or compounds, similar to the refractive and the material Any material having a can be obtained an antireflection film having equivalent properties.

  The spectral reflectance characteristics of the optical lenses A, B, and C thus obtained are shown in FIG. The reflectance in the wavelength range from 420 nm to 650 nm is 0.2% or less, and the difference between the maximum value and the minimum value in the wavelength range from 430 nm to 650 nm (hereinafter referred to as PV difference) is 0.18%. It was the following.

According to the antireflection film 2, the number of layers is relatively small, that is, five layers, and the first layer to the third layer are the low refractive index layer 3 or the intermediate refractive index layer 5. It is possible to suppress coloring and reduce coloring in the visible range and obtain a high antireflection effect. Further, it is not necessary to include a relatively thin layer having a physical film thickness of 15 nm or less that is easily affected by manufacturing errors, and stable film formation with less errors can be realized at low cost.
Furthermore, the optical lenses A, B, and C on which these are laminated can also obtain good transmittance with little coloring in the visible range.

Next, a second embodiment will be described with reference to FIGS. 3 and 4 and Table 2. FIG.
In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and description is abbreviate | omitted.
The difference between the second embodiment and the first embodiment is that the antireflection film 8 of the optical lens D according to the second embodiment is made of S-BAL35 manufactured by OHARA INC. As shown in Table 2. The first and third layers counted from the lens 10 having a surface top thickness of 1 mm and a refractive index of 1.59 are, for example, an intermediate refractive index layer 11 made of Al ₂ O ₃ , and the second layer. Is a low refractive index layer 12 made of, for example, SiO ₂ , a fourth layer is made of, for example, a high refractive index layer 13 made of ZrO ₂ , and a fifth layer is, for example, a low refractive index layer made of MgF _2. This is a point of 15.

  In the same manner as the optical lens D, an optical lens E in which an antireflection film is laminated on a lens made of S-LAL8 manufactured by OHARA INC. And having a top thickness of 1 mm and a refractive index of 1.71; An optical lens F made of S-TIH53 manufactured by OHARA INC. And having an antireflection film laminated on a lens having a top thickness of 1 mm and a refractive index of 1.85 was prepared. Table 2 shows the refractive index of the material constituting each layer in the wavelength range of 350 nm to 800 nm, and the optical film thickness nd (n is the refractive index, d is the physical film thickness) of each layer at this time.

FIG. 4 shows the spectral reflectance characteristics of the optical lenses D, E, and F thus obtained. The reflectance in the wavelength range from 420 nm to 660 nm is 0.15% or less, and the difference between the maximum value and the minimum value in the wavelength range from 430 nm to 650 nm (hereinafter referred to as PV difference) is 0.17%. It was the following.
According to the antireflection film 13 and the optical lenses D, E, and F, the same effect as that of the first embodiment can be obtained.

Next, a third embodiment will be described with reference to FIGS.
In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and description is abbreviate | omitted.
The optical lens unit 16 according to this embodiment includes six lenses having a refractive index of 1.52 and a top thickness of 2 mm to 10 mm. The G side is a light incident side, and the L side is a light emission side. On the side. The reflection surfaces of all the six lenses, that is, the 12 reflection surfaces are each provided with an antireflection film shown in B of Table 1.

  According to this optical lens unit 16, as shown in FIG. 6, the transmittance is 98.5% or more in the wavelength range of 430 nm to 650 nm, and the PV difference can be 1.1%. Therefore, when observing the object, it is possible to ensure a sufficient brightness of the observation image and obtain an observation image with good color balance without coloring.

Next, a fourth embodiment will be described with reference to FIG.
In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and description is abbreviate | omitted.
The optical lens unit 17 according to this embodiment is composed of S-FPL53 manufactured by OHARA INC., And has a refractive index of 1.44 and a thickness of 1 mm on both surfaces of five parallel flat plates, that is, 10 surfaces. An optical lens having an antireflection film having the film structure shown in FIG. 5 and S-BSL7 manufactured by OHARA INC., On both surfaces of 10 parallel flat plates having a refractive index of 1.52 and a thickness of 1 mm, that is, 20 surfaces, An optical lens having an antireflection film having the film configuration shown as B in Table 1 and both surfaces of five parallel flat plates each having a refractive index of 1.59 and a thickness of 1 mm consisting of S-BAL35 manufactured by OHARA INC. An optical lens having an antireflection film having the film configuration shown by C in Table 1 is provided on 10 surfaces, and these 20 parallel flat plates, that is, all 40 surfaces are connected in series.

  According to this optical lens unit 17, as shown in FIG. 7, the transmittance can be 95% or more in the wavelength range of 430 nm to 650 nm. Therefore, when observing the object, it is possible to ensure a sufficient brightness of the observation image and obtain an observation image with good color balance without coloring.

Next, a fifth embodiment will be described with reference to FIG.
In addition, the same code | symbol is attached | subjected to the component similar to 1st Embodiment mentioned above, and description is abbreviate | omitted.
The optical lens unit 18 according to the present embodiment is made of S-FPL53 manufactured by OHARA INC. And has 10 refractive plates with a refractive index of 1.44 and a thickness of 1 mm. An optical lens having an antireflection film having the film structure shown in FIG. 5 and S-BSL7 manufactured by OHARA INC., On both surfaces of 15 parallel flat plates having a refractive index of 1.52 and a thickness of 1 mm, that is, 30 surfaces, An optical lens having an antireflection film having the film configuration shown as B in Table 1 and both surfaces of 15 parallel flat plates each having a refractive index of 1.59 and a thickness of 1 mm made of OHARA S-BAL35, ie, An optical lens having an antireflection film having the film configuration shown in C in Table 1 is provided on 30 surfaces, and these 40 parallel flat plates, that is, all 80 surfaces are connected in series.

  According to this optical lens unit 18, as shown in FIG. 8, the transmittance can be 90% or more in the wavelength range of 430 nm to 650 nm. Therefore, when observing the object, it is possible to ensure a sufficient brightness of the observation image and obtain an observation image with good color balance without coloring.

The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, in the above-described embodiment, the length of the top surface of the substrate is described as 1 mm, or 2 mm to 10 mm. However, when measuring reflectance or transmittance, it should be applied regardless of the thickness of the substrate. Can do.
Further, since the optical lenses according to the fourth and fifth embodiments are parallel flat plates, the arrangement order, the plate thickness, and the flat plate interval may be arbitrary.
Although the parallel plate is used in the fourth and fifth embodiments, an optical lens having a lens surface having a curvature is used instead of the parallel plate, and the arrangement order, lens thickness, and lens surface interval are taken into consideration. If this is done, the same effect can be obtained.

As a comparative example, the design wavelength λ = 510 nm, the refractive index of the base material is 1.52, the refractive index of the first layer counted from the base material is 1.60, the film thickness is 1 × λ / 4, the second layer Of a generally known three-layer antireflection film having a refractive index of 2.0, a film thickness of 2 × λ / 4, a refractive index of the third layer of 1.38, and a film thickness of 1 × λ / 4. The spectral reflection characteristics are shown in FIG.
Further, FIG. 6 shows spectral transmittance characteristics when this antireflection film is applied to all the 12 reflection surfaces of the optical lens unit similar to the third embodiment of the present invention. Spectral transmittance characteristics when applied to all 40 reflecting surfaces of 20 parallel flat plates made of S-BSL7 with a thickness of 1 mm and a refractive index of 1.52 are shown in FIG. FIG. 8 shows spectral transmittance characteristics when applied to all 80 reflecting surfaces of both 40 parallel flat plates made of S-BSL7 manufactured by OHARA and having a thickness of 1 mm and a refractive index of 1.52.

As a result, as shown in FIG. 9, the spectral reflectance of the antireflection film in the comparative example is 0 to 0.4% in the wavelength range of 420 nm to 660 nm, and is close to 0.4% near 510 nm. The spectral reflectance characteristic has a reflectance peak. On the other hand, in this embodiment, as shown in FIGS. 2 and 4, the reflectance peak is 0.18% or less in the wavelength range of 420 nm to 660 nm.
From this, it can be seen that the optical lens according to the present embodiment can obtain a good transmittance with little coloring in the visible range.
The transmittance of the entire optical unit system of the comparative example is 95.5% or more in the wavelength range of 430 nm to 650 nm, and the PV difference is 4.3%. On the other hand, in this embodiment, as shown in FIG. 6, the transmittance is 98.5% or more and the PV difference is 1.1%. Furthermore, since the transmittance is 90% or more in the visible range of wavelengths from 400 nm to 700 nm including the cases shown in FIGS. 7 and 8, when observing the object with the optical lens unit according to the present embodiment. It can be seen that the brightness of the observation image can be sufficiently secured and a good observation image with less coloring can be obtained.

It is sectional drawing which shows the optical lens in 1st Embodiment based on this invention. It is a graph which shows the spectral reflectance characteristic of the antireflection film in a 1st embodiment concerning the present invention. It is sectional drawing which shows the optical lens in 2nd Embodiment based on this invention. It is a graph which shows the spectral reflectance characteristic of the antireflection film in the 2nd embodiment concerning the present invention. It is a side view which shows the optical lens unit in the 3rd Embodiment concerning this invention. It is a graph which shows the spectral transmittance characteristic of the optical lens unit in the 3rd Embodiment concerning this invention, and a comparative example. It is a graph which shows the spectral transmittance characteristic of the optical lens unit in the 4th Embodiment concerning this invention, and a comparative example. It is a graph which shows the spectral transmittance characteristic of the optical lens unit in the 5th Embodiment concerning this invention, and a comparative example. It is a graph which shows the spectral reflectance characteristic in the comparative example of an antireflection film.

Explanation of symbols

1, 10 Lens (base material)
2, 8, 12, 13 Antireflection film 3, 7, 12, 15 Low refractive index layer 5, 11 Intermediate refractive index layer 6, 13 High refractive index layer 16, 17, 18 Optical lens unit A, D Optical lens

Claims (11)

An antireflection film provided on a substrate,
A low refractive index layer made of a low refractive index material having a relatively low refractive index of the first, third, and fifth layers counted from the base material,
The fourth layer is a high refractive index layer made of a high refractive index material having a relatively high refractive index,
The second layer has a refractive index that is higher than that of the low refractive index material and lower than that of the high refractive index material.
The optical film thickness of the first layer is 0.15 × λ / 4 or more and 2.2 × λ / 4 or less with respect to the design wavelength λ,
The optical film thickness of the second layer is 0.1 × λ / 4 or more and 0.8 × λ / 4 or less with respect to the design wavelength λ,
The optical thickness of the third layer is 0.1 × λ / 4 or more and 0.38 × λ / 4 or less with respect to the design wavelength λ,
The optical film thickness of the fourth layer is 1.8 × λ / 4 or more and 2.2 × λ / 4 or less with respect to the design wavelength λ,
An antireflection film, wherein the optical thickness of the fifth layer is 0.8 × λ / 4 or more and 1.2 × λ / 4 or less with respect to a design wavelength λ. An antireflection film provided on a substrate,
A low refractive index layer made of a low refractive index material having a relatively low refractive index of the second and fifth layers counted from the base material,
The fourth layer is a high refractive index layer made of a high refractive index material having a relatively high refractive index,
The first and third layers have a refractive index that is higher than that of the low refractive index material and lower than that of the high refractive index material.
The optical film thickness of the first layer is 0.3 × λ / 4 or more and 1.8 × λ / 4 or less with respect to the design wavelength λ,
The optical film thickness of the second layer is 0.12 × λ / 4 or more and 0.60 × λ / 4 or less with respect to the design wavelength λ,
The optical film thickness of the third layer is 0.7 × λ / 4 or more and 1.8 × λ / 4 or less with respect to the design wavelength λ,
The optical film thickness of the fourth layer is 1.8 × λ / 4 or more and 2.2 × λ / 4 or less with respect to the design wavelength λ,
An antireflection film, wherein the optical thickness of the fifth layer is 0.8 × λ / 4 or more and 1.2 × λ / 4 or less with respect to a design wavelength λ. The refractive index in the wavelength range of 350 nm to 800 nm of the low refractive index layer is 1.3 or more and less than 1.5,
The refractive index in the wavelength range of 350 nm to 800 nm of the intermediate refractive index layer is 1.5 or more and less than 1.85,
3. The antireflection film according to claim 1, wherein the high refractive index layer has a refractive index of 1.85 or more and less than 2.7 in a wavelength range of 350 nm to 800 nm. The high refractive index _{material, CeO 2, Cr 2 O 3} , In 2 O 3, SnO 2, ZnS, WO 3, TiOx (0 ≦ x ≦ 2), HfO 2, ZrO 2, Ta 2 O 5, Y 2 The antireflection film according to claim 1, comprising at least one of O ₃ , Pr ₆ O ₁₁ , Nb ₂ O ₅ , La ₂ O ₃ , and lanthanum titanate. . 5. The antireflection film according to claim 1, wherein the intermediate refractive material includes at least one of SiO, Al ₂ O ₃ , CeF ₃ , LaF ₃ , and MgO. The antireflective film according to claim 1, wherein the low refractive material includes at least one of Na ₃ AlF ₆ , SiO ₂ , and MgF ₂ . The substrate is a lens;
An optical lens comprising the antireflection film according to any one of claims 1 to 6.   8. The optical lens according to claim 7, wherein the reflectance of the antireflection film is 0.2% or less in a wavelength range of 420 nm to 660 nm. An optical lens unit comprising a plurality of optical lenses,
An optical lens unit comprising at least one optical lens according to claim 7.   10. The optical lens unit according to claim 9, wherein in a wavelength range of 430 nm to 650 nm, the transmittance when the optical lens is connected to 1 to 40 surfaces is 95% or more. 10. The optical lens unit according to claim 9, wherein in a wavelength range of 430 nm to 650 nm, the transmittance when the optical lens is connected to 1 to 80 surfaces is 90% or more.

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