JP2009003214A - Absorption type multilayer film nd filter, its manufacturing apparatus, and manufacturing method of absorption type multilayer film nd filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an absorption type multilayer film ND filter which can be stably manufactured with sufficient reproducibility and to provide a manufacturing apparatus and a manufacturing method of the absorption type multilayer film ND filter. <P>SOLUTION: The absorption type multilayer film ND filter includes an absorption type multilayer film made by alternately laminating an oxide dielectric film layer and a metal absorption film layer on at least one surface of film substrates 15,16 and the absorption type multilayer film has gradation concentration distribution. The oxide dielectric film layer and the metal absorption film layer are respectively film-formed by sputtering. Further after film formation by sputtering, each metal absorption film layer is irradiated with ion beams containing oxygen and thereby transmittance of an irradiated part becomes higher than that of a non-irradiated part and further an extinction coefficient of the metal absorption film layer continuously decreases toward a center part from a peripheral part of irradiated ion beams 20 and the irradiated part has the gradation concentration distribution. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an absorptive multilayer ND filter having a gradation density distribution, and in particular, an absorptive multilayer ND filter that can be stably manufactured with high reproducibility, a manufacturing apparatus thereof, and a manufacturing of the absorptive multilayer ND filter It is about the method.

  Recently, ND filters that attenuate transmitted light in the visible range have been widely used, and this type of ND (Neutral Density Filter) filter includes a reflective ND filter that reflects and attenuates incident light, Absorptive ND filters that absorb and attenuate incident light are known. In addition, when an ND filter is incorporated in a lens optical system in which reflected light is a problem, an absorption ND filter is generally used. In this absorption ND filter, an absorbing substance is mixed in the substrate itself (colored glass ND filter) or There are a type in which an absorbing material is applied and a type in which the thin film formed on the surface of the substrate has no absorption and has absorption. In the latter case, an absorption-type multilayer ND filter is also known in which the thin film is formed of a multilayer film to prevent reflection on the surface of the thin film, and has an antireflection effect as well as a function of attenuating transmitted light.

By the way, in the above-mentioned absorption multilayer ND filter used for a small and thin digital camera, since the installation space is narrow, it is necessary to make the substrate itself thin, and a resin film is the optimum substrate. As this type of absorption multilayer ND filter, Patent Document 1 discloses an absorption multilayer ND filter comprising an oxide dielectric film layer such as SiO ₂ and a metal absorption film layer such as Ni.

  On the other hand, in a video camera that captures a moving image, the amount of incident light sequentially changes. For this reason, an ND filter used in a video camera is required to have a function capable of changing the amount of transmitted light according to the amount of incident light. In order to meet such a demand, an ND filter having a gradation density distribution in which the transmittance gradually decreases from the center of the optical axis in the radial direction is required, and an ND filter having a gradation density distribution is optimal. It can be solved by moving to a density position where the amount of transmitted light is used. That is, when the amount of incident light is high, the portion with a high density of the ND filter (portion with low transmittance) is used by moving it on the optical axis, and when the amount of incident light is low, the portion with a low density of the ND filter (portion with high transmittance). ) Can be used by moving it on the optical axis. Since the amount of light incident on the video camera is constantly changing, the ND filter having the gradation density distribution is constantly moving in the radial direction.

  Two methods are generally known for manufacturing an ND filter having such a gradation density distribution. For example, as described in Patent Document 2, a method of generating a film thickness distribution using a shielding means such as a mask at the time of film formation of the absorption film, and during film formation of the absorption film as described in Patent Document 3 This is a method of generating a distribution in the extinction coefficient by controlling the partial pressure of oxygen. In these methods, when the absorption film is formed, a gradation density distribution is applied to the absorption film with a distribution of film thickness and a distribution of extinction coefficient.

However, the method of using a shielding means such as a mask at the time of forming the absorption film requires a complicated mask and an operating mechanism because the film thickness distribution is generated at the same time as the film formation. There was a problem that it was difficult to obtain a good quality absorption film. On the other hand, the method of generating the distribution in the extinction coefficient of the absorption film by controlling the oxygen partial pressure during film formation is difficult to maintain reproducibility because it is easily affected by the gas generated from the film substrate, and the exhaust There was a problem that the capacity of the pump was likely to decrease over time.
JP 2006-178395 A JP 2005-345747 A JP 2004-212462 A

  The present invention has been made paying attention to such problems, and an object of the present invention is to provide an absorption-type multilayer ND filter having a gradation distribution that can be stably manufactured with high reproducibility. An object of the present invention is to provide an apparatus for manufacturing an absorption multilayer ND filter having a gradation distribution and a method for manufacturing an absorption multilayer ND filter using this apparatus.

  Therefore, as a result of intensive studies by the present inventors, a part of the metal absorption film layer formed by sputtering was irradiated with an ion beam containing oxygen to oxidize a part of the metal absorption film layer. In this case, there is a continuous difference in the degree of oxidation in the metal absorption film layer from the periphery to the center of the irradiated ion beam, and the metal absorption film layer from the periphery to the center of the irradiated ion beam. It was confirmed that the extinction coefficient of the sapphire decreased continuously and a distribution existed in the transmittance of the metal absorption film layer. Further, an oxide dielectric film layer and a metal absorption film layer are sequentially formed on one side of the film substrate by sputtering, and an ion beam containing oxygen is irradiated to a part of the metal absorption film layer after the film formation. Absorption-type multilayer film in which an oxide dielectric film layer and a metal absorption film layer are alternately laminated by repeatedly forming a dielectric film layer and a metal absorption film layer and ion beam irradiation to the formed metal absorption film layer As a result, the absorption with a gradation distribution was punched out by punching out the boundary between the region of the metal absorption film layer whose transmittance was increased by the ion beam irradiation and the region not irradiated with the ion beam. It has been found that type multilayer ND filters can be manufactured stably with good reproducibility. The present invention has been completed by such technical discovery.

That is, the invention according to claim 1
An absorption type multilayer film comprising an oxide dielectric film layer and a metal absorption film layer alternately laminated on at least one surface of a film substrate, and the absorption type multilayer film has a gradation density distribution. Assuming a multilayer ND filter,
The oxide dielectric film layer and the metal absorption film layer are formed by sputtering, and each metal absorption film layer is irradiated with an ion beam containing oxygen after the sputtering film formation so that the transmittance of the irradiated portion is not irradiated. It is higher than the area, and the extinction coefficient of the metal absorption film layer continuously decreases from the periphery to the center of the irradiated ion beam, and the irradiation area has a gradation density distribution. It is characterized by.

The invention according to claim 2
Assuming a manufacturing device for an absorption-type multilayer ND filter having a gradation density distribution,
A sputtering chamber equipped with a vacuum pump;
A single unit provided adjacent to the sputtering chamber and accommodates a plurality of sheet-like film substrates, and allows the sheet-like film substrate to be taken into and out of the sputtering chamber without opening the sputtering chamber to the atmosphere. Or a pair of load lock chambers,
The sheet-like film substrate is held and carried from the load lock chamber to the sputtering chamber, and the conveyance direction of the sheet-like film substrate carried in the sputtering chamber is conveyed in a reversible manner, and the film is processed in the sputtering chamber. And a plurality of holders for carrying the film-like film substrate to the same or other load lock chambers,
In the sputtering chamber, two sputtering cathodes and an ion beam generator are arranged along the conveying direction of the sheet film substrate, and a target for forming an oxide dielectric film layer is attached to one of the sputtering cathodes. On the other side, a target for forming a metal absorption film layer is attached,
An oxide dielectric film layer and a metal absorption film layer are sequentially formed by a sputtering cathode on a sheet-like film substrate transported in a sputtering chamber, and a mixed ion beam of argon and oxygen is generated by an ion beam generator. The ion beam is irradiated onto a part of the metal absorption film layer after the film formation, and the oxide dielectric film layer and the metal absorption film layer are formed and formed while the conveying direction of the sheet-like film substrate is reversed. The step of ion beam irradiation to the metal absorption film layer is repeated to form an absorption multilayer film in which oxide dielectric film layers and metal absorption film layers are alternately stacked,
The invention according to claim 3
Assuming a manufacturing device for an absorption-type multilayer ND filter having a gradation density distribution,
A sputtering chamber equipped with a vacuum pump;
A first roll and a second roll which are provided in the sputtering chamber to wind and unwind the belt-like film substrate, a can roll which is provided in a transport path between the first roll and the second roll and on which the belt-like film substrate is wound; Two sputtering cathodes provided along the outer peripheral surface of the can roll and at least one ion beam generator;
A target for forming an oxide dielectric film layer is attached to one of the sputtering cathodes, and a target for forming a metal absorption film layer is attached to the other,
The second roll or the first roll while forming the oxide dielectric film layer with one sputtering cathode on the belt-like film substrate unwound from the first roll or the second roll and conveyed along the outer peripheral surface of the can roll After the necessary amount of the belt-shaped film substrate is wound up by the above, the other sputtering cathode with respect to the belt-shaped film substrate that is conveyed along the outer peripheral surface of the can roll with the rotation directions of the first roll, the second roll, and the can roll reversed. The metal absorbing film layer is formed by the above method, and a mixed ion beam of argon and oxygen is generated by the ion beam generator, and the first roll or the second roll is applied while irradiating a part of the metal absorbing film layer after the film formation. Winding with two rolls, and then repeating these series of steps, the oxide dielectric film layer and the metal absorption film layer were alternately laminated. And forming a Osamugata multilayer film.

The invention according to claim 4
Assuming an apparatus for manufacturing an absorption-type multilayer ND filter according to the invention of claim 3,
A plurality of guide rolls are provided between the first roll and the can roll and between the second roll and the can roll, respectively, and the first roll side guide roll and the second roll side guide roll are conveyed to the belt-like film substrate. And an ion beam generator for irradiating an ion beam containing oxygen, respectively, between the guide roll on the first roll side and the sputtering cathode and between the guide roll on the second roll side and the sputtering cathode on the outer peripheral surface of the can roll. An ion beam generator for irradiating an ion beam containing oxygen to a belt-shaped film substrate transported along, respectively, is provided,
The invention according to claim 5
Assuming an apparatus for manufacturing an absorption-type multilayer ND filter according to any one of claims 2 to 4,
A plurality of ion beam generators are provided side by side along the width direction of the film substrate to be conveyed.

Next, the invention according to claim 6 is:
On the premise of a method of manufacturing an absorption multilayer ND filter having a gradation density distribution using the manufacturing apparatus according to claim 2,
A first step of holding the sheet-like film substrate accommodated in the load lock chamber with a holder;
A second step of bringing the sheet-like film substrate held by the holder into the evacuated sputtering chamber;
An oxide dielectric film layer and a metal absorption film layer are sequentially formed by two sputtering cathodes on the sheet-like film substrate conveyed in the sputtering chamber, and a mixed ion beam of argon and oxygen is produced by an ion beam generator. And a third step of irradiating a part of the metal absorption film layer after film formation with this ion beam,
Reversing the conveying direction of the sheet-like film substrate, the sheet is formed by repeating the process of forming the oxide dielectric film layer and the metal absorption film layer and the ion beam irradiation on the formed metal absorption film layer as necessary. A fourth step of forming an absorptive multilayer film on the surface of the film substrate;
The sheet-like film substrate with the absorption multilayer film formed on the surface is carried out to the same or another load lock chamber, and the sheet-like film substrate is turned upside down in the load lock chamber, and then this sheet-like film substrate is used as a holder. And a fifth step for carrying it into the sputtering chamber,
A sixth step of forming the absorptive multilayer film on the back surface of the sheet-like film substrate by repeating the third step and the fourth step in the sputtering chamber;
Gradation of sheet-like film substrate with absorption multilayer film formed on the back side is carried out to the same or other load-lock chamber, and sheet-like film substrate with absorption multilayer film is formed on the front and back surfaces. A seventh step of obtaining an absorption-type multilayer ND filter having a concentration distribution;
It is characterized by comprising,
The invention according to claim 7 provides:
On the premise of a method of manufacturing an absorption multilayer ND filter having a gradation concentration distribution using the manufacturing apparatus according to claim 3,
A first step of setting the strip film substrate on the first roll or the second roll in the sputtering chamber;
After evacuating the sputtering chamber, the belt-shaped film substrate set on the first roll or the second roll is transported along the outer peripheral surface of the can roll while unwinding, and one of the sputtering provided along the outer peripheral surface of the can roll A second step of winding with a second roll or a first roll while forming an oxide dielectric film layer with a cathode;
After the winding of the belt-like film substrate to the second roll or the first roll is completed, the belt-like film is conveyed along the outer peripheral surface of the can roll with the rotation directions of the first roll, the second roll and the can roll reversed. A metal absorption film layer is formed on the substrate by the other sputtering cathode, and a mixed ion beam of argon and oxygen is generated by an ion beam generator, and this ion beam is irradiated to a part of the metal absorption film layer after film formation. While the third step of winding with the first roll or the second roll,
The above-described oxide dielectric film layer and metal absorption film layer are formed, and the treatment using the ion beam irradiation as a unit to the formed metal absorption film layer is repeated as many times as necessary to form an absorption type multilayer film on the surface of the belt-like film substrate. A fourth step to be formed;
A fifth step of wrapping the first roll or the second roll while removing the band-shaped film substrate having the absorption multilayer film formed on the surface from the first roll or the second roll and inverting the front and back of the band-shaped film substrate;
After evacuating the sputtering chamber, the front and back sides are reversed, and the second to fourth steps are repeated on the belt-like film substrate wound around the first roll or the second roll. A sixth step of forming a film;
A seventh step of obtaining an absorptive multilayer ND filter having a gradation density distribution by punching a band-shaped film substrate having an absorptive multilayer film formed on the front and back surfaces;
It is characterized by comprising.

The invention according to claim 8 is
Based on the manufacturing method of the absorption-type multilayer ND filter according to the invention of claim 6 or 7,
The irradiation position of the ion beam to the metal absorption film layer formed on the front and back surfaces of the sheet-like film substrate or the belt-like film substrate is shifted in the width direction between the front and back surfaces of the sheet-like film substrate or the belt-like film substrate. It is characterized by
The invention according to claim 9 is:
Based on the manufacturing method of the absorption type multilayer ND filter according to the invention of claim 6, 7 or 8,
The metal absorption film layer is made of a material whose extinction coefficient is reduced by oxidation,
The invention according to claim 10 is:
Based on the manufacturing method of the absorption-type multilayer ND filter according to the invention of claim 9,
The material whose extinction coefficient decreases by oxidation is Ni or a Ni alloy.

According to the absorption multilayer ND filter according to the invention of claim 1,
Each of the oxide dielectric film layer and the metal absorption film layer is formed by sputtering, and each metal absorption film layer is irradiated with an ion beam containing oxygen after the sputtering film formation so that the transmittance of the irradiated region is not irradiated. As it is higher, the extinction coefficient of the metal absorption film layer continuously decreases from the peripheral part of the irradiated ion beam toward the central part, and the irradiation part has a gradation density distribution. An absorption multilayer ND filter having a gradation density distribution can be manufactured with good reproducibility.

Moreover, according to the absorption multilayer ND filter manufacturing apparatus according to the invention of claim 2,
An oxide dielectric film layer and a metal absorption film layer are sequentially formed by a sputtering cathode on a sheet-like film substrate transported in a sputtering chamber, and a mixed ion beam of argon and oxygen is generated by an ion beam generator. The ion beam is irradiated onto a part of the metal absorption film layer after the film formation, and the oxide dielectric film layer and the metal absorption film layer are formed and formed while the conveying direction of the sheet-like film substrate is reversed. Each step of ion beam irradiation to the metal absorption film layer is repeated to form an absorption multilayer film in which oxide dielectric film layers and metal absorption film layers are alternately stacked. It is possible to manufacture the absorption-type multilayer ND filter having reproducibility,
In the manufacturing apparatus of the absorption type multilayer ND filter according to the invention of claim 3,
The second roll or the first roll while forming the oxide dielectric film layer with one sputtering cathode on the belt-like film substrate unwound from the first roll or the second roll and conveyed along the outer peripheral surface of the can roll After the necessary amount of the belt-shaped film substrate is wound up by the above, the other sputtering cathode with respect to the belt-shaped film substrate that is conveyed along the outer peripheral surface of the can roll with the rotation directions of the first roll, the second roll, and the can roll reversed. The metal absorbing film layer is formed by the above method, and a mixed ion beam of argon and oxygen is generated by the ion beam generator, and the first roll or the second roll is applied while irradiating a part of the metal absorbing film layer after the film formation. Winding with two rolls, and then repeating these series of steps, the oxide dielectric film layer and the metal absorption film layer were alternately laminated. Since forming the Osamugata multilayer film, it is possible to manufacture the absorption type multi-layer film ND filter good reproducibility with gradated density distribution.

Next, according to the manufacturing method of the absorption multilayer ND filter according to the invention of claim 6,
A first step of holding the sheet-like film substrate accommodated in the load lock chamber with a holder;
A second step of bringing the sheet-like film substrate held by the holder into the evacuated sputtering chamber;
An oxide dielectric film layer and a metal absorption film layer are sequentially formed by two sputtering cathodes on the sheet-like film substrate conveyed in the sputtering chamber, and a mixed ion beam of argon and oxygen is produced by an ion beam generator. And a third step of irradiating a part of the metal absorption film layer after film formation with this ion beam,
Reversing the conveying direction of the sheet-like film substrate, the sheet is formed by repeating the process of forming the oxide dielectric film layer and the metal absorption film layer and the ion beam irradiation on the formed metal absorption film layer as necessary. A fourth step of forming an absorptive multilayer film on the surface of the film substrate;
The sheet-like film substrate with the absorption multilayer film formed on the surface is carried out to the same or another load lock chamber, and the sheet-like film substrate is turned upside down in the load lock chamber, and then this sheet-like film substrate is used as a holder. And a fifth step for carrying it into the sputtering chamber,
A sixth step of forming the absorptive multilayer film on the back surface of the sheet-like film substrate by repeating the third step and the fourth step in the sputtering chamber;
Gradation of sheet-like film substrate with absorption multilayer film formed on the back side is carried out to the same or other load-lock chamber, and sheet-like film substrate with absorption multilayer film is formed on the front and back surfaces. A seventh step of obtaining an absorption-type multilayer ND filter having a concentration distribution;
It has
Further, in the manufacturing method of the absorption-type multilayer ND filter according to the invention of claim 7,
A first step of setting the strip film substrate on the first roll or the second roll in the sputtering chamber;
After evacuating the sputtering chamber, the belt-shaped film substrate set on the first roll or the second roll is transported along the outer peripheral surface of the can roll while unwinding, and one of the sputtering provided along the outer peripheral surface of the can roll A second step of winding with a second roll or a first roll while forming an oxide dielectric film layer with a cathode;
After the winding of the belt-like film substrate to the second roll or the first roll is completed, the belt-like film is conveyed along the outer peripheral surface of the can roll with the rotation directions of the first roll, the second roll and the can roll reversed. A metal absorption film layer is formed on the substrate by the other sputtering cathode, and a mixed ion beam of argon and oxygen is generated by an ion beam generator, and this ion beam is irradiated to a part of the metal absorption film layer after film formation. While the third step of winding with the first roll or the second roll,
The above-described oxide dielectric film layer and metal absorption film layer are formed, and the treatment using the ion beam irradiation as a unit to the formed metal absorption film layer is repeated as many times as necessary to form an absorption type multilayer film on the surface of the belt-like film substrate. A fourth step to be formed;
A fifth step of wrapping the first roll or the second roll while removing the band-shaped film substrate having the absorption multilayer film formed on the surface from the first roll or the second roll and inverting the front and back of the band-shaped film substrate;
After evacuating the sputtering chamber, the front and back sides are reversed, and the second to fourth steps are repeated on the belt-like film substrate wound around the first roll or the second roll. A sixth step of forming a film;
A seventh step of obtaining an absorptive multilayer ND filter having a gradation density distribution by punching a band-shaped film substrate having an absorptive multilayer film formed on the front and back surfaces;
Therefore, the absorption multilayer ND filter having a gradation density distribution can be stably manufactured with good reproducibility.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(1) Film structure of absorption multilayer ND filter First, a film structure (see Table 1) of an absorption multilayer ND filter having an average transmittance of 6.3% at a wavelength of 400 to 700 nm was designed. FIG. 5 shows the spectral transmittance of the designed absorption multilayer ND filter. The spectral transmission characteristics of the ND filter were measured using a self-recording spectrophotometer (V570 manufactured by JASCO Corporation).

  The absorption multilayer ND filter of the present invention having a gradation density distribution is manufactured based on the absorption multilayer ND filter having an average transmittance of 6.3% using the manufacturing apparatus of the present invention described below. ing.

（２）吸収型多層膜ＮＤフィルターを製造する第一の製造装置
本発明に係る吸収型多層膜ＮＤフィルターを製造する第一の製造装置は、一般的にロードロック式、インターバック式、連続式等と呼ばれるもので、シート形状に切断された基板（シート状フィルム基板）面にスパッタリングによる成膜を施す装置であり、例えば、図１に示すような構造を有している。

(2) First manufacturing apparatus for manufacturing the absorption multilayer ND filter The first manufacturing apparatus for manufacturing the absorption multilayer ND filter according to the present invention is generally a load lock type, an inter-back type, a continuous type. This is an apparatus for forming a film by sputtering on the surface of a substrate (sheet-like film substrate) cut into a sheet shape, and has a structure as shown in FIG. 1, for example.

  That is, the first manufacturing apparatus according to the present invention includes a sputtering chamber 11 having a vacuum pump (not shown), and a plurality of sheet-like film substrates (not shown) provided adjacent to the sputtering chamber 11 and provided therein. And a single load lock chamber 10 that allows the sheet-like film substrate to be taken in and out of the sputtering chamber 11 without opening the sputtering chamber 11 to the atmosphere, and a load that holds the sheet-like film substrate. The sheet-like film substrate 15 that has been brought into the sputtering chamber 11 from the lock chamber 10 and is conveyed so that the carrying direction of the sheet-like film substrate 15 carried in the sputtering chamber 11 can be reversed and film-formed in the sputtering chamber 11 is the same. A plurality of holders (not shown) to be carried out to the load lock chamber 10 It is provided.

  In the manufacturing apparatus shown in FIG. 1, a single load lock chamber 10 is provided. However, the load lock chamber may be provided on both sides of the sputtering chamber 11 in the center.

In the sputtering chamber 11, two sputtering cathodes 13 and 14 and an ion beam generator 12 are arranged along the conveying direction of the sheet-like film substrate 15. One of the sputtering cathodes 14 has an oxide dielectric material. A target (not shown) for forming a film layer (for example, SiO ₂ film layer) is attached, and a target (not shown) for forming a metal absorption film layer (for example, Ni alloy layer) is formed on the other sputtering cathode 13. Is attached.

  Then, the oxide dielectric film layer and the metal absorption film layer are formed by the two sputtering cathodes 13 and 14 on the sheet-like film substrate 15 conveyed from the right to the left in the drawing in the sputtering chamber 11 shown in FIG. The film is sequentially formed, and the ion beam generator 12 generates a mixed ion beam of argon and oxygen to irradiate a part of the metal absorption film layer after the film formation. After reversing the transport direction and returning it to the initial position of film formation, again forming the oxide dielectric film layer and the metal absorption film layer and reversing the metal absorption film while reversing the transport direction of the sheet-like film substrate One side (surface) of the sheet-like film substrate 15 is formed by repeating each step of ion beam irradiation to the film layer to form an absorption multilayer film in which oxide dielectric film layers and metal absorption film layers are alternately stacked. It can be formed.

As shown in Table 1, in order to form the absorption multilayer film on both the front and back surfaces of the sheet-like film substrate 15, the same load lock is applied to the sheet-like film substrate 15 having the absorption multilayer film formed on one side (front surface). The sheet-like film substrate is carried out into the chamber 10 or another load lock chamber (not shown), and the sheet-like film substrate is turned upside down in the load-lock chamber. Bring it in again. Then, the oxide dielectric film layer and the metal absorption film layer described above are formed on the back surface of the sheet-like film substrate, and the steps of the ion beam irradiation to the formed metal absorption film layer are repeated. An absorption-type multilayer film in which dielectric film layers and metal absorption film layers are alternately stacked may be formed.
(3) Second manufacturing apparatus for manufacturing the absorption multilayer ND filter The second manufacturing apparatus for manufacturing the absorption multilayer ND filter according to the present invention is generally called a roll coater, An apparatus for forming a film by sputtering on a substrate (band-shaped film substrate) surface, for example, has a structure as shown in FIG.

  That is, the second manufacturing apparatus according to the present invention includes a sputtering chamber 11 having a vacuum pump (not shown), and a first roll 1 provided in the sputtering chamber 11 for winding and unwinding the belt-like film substrate 16. In addition, the second roll 2, the water-cooled can roll 3 provided in the conveyance path between the first roll 1 and the second roll 2, and the band-shaped film substrate 16 is wound around, and between the first roll 1 and the water-cooled can roll 3. And four guide rolls 21, 22, 23, 24 provided between the second roll 2 and the water-cooled can roll 3, and the first roll 1 and the second roll 2 are tensioned by a powder clutch. Balance is maintained. Moreover, the conveyance direction of the strip | belt-shaped film board | substrate 16 is decided by rotation of the water cooling can roll 3, and in this specification, the strip | belt-shaped film board | substrate 16 is wound up from the 1st roll 1 to the 2nd roll 2 side. The rotation direction of the water-cooled can roll 3 is defined as the forward rotation direction, and the rotation direction of the water-cooled can roll 3 wound from the second roll 2 to the first roll 1 side is defined as the reverse rotation direction.

In the sputtering chamber 11, two sputtering cathodes 4 and 5 are disposed along the outer peripheral surface of the water-cooled can roll 3. One of the sputtering cathodes 4 has an oxide dielectric film layer (for example, SiO _2). A target (not shown) for forming a film layer) is attached, and a target (not shown) for forming a metal absorption film layer (for example, Ni alloy layer) is attached to the other sputtering cathode 5.

  Further, in the sputtering chamber 11, two ion beam generators 8 and 9 are disposed along the outer peripheral surface of the water-cooled can roll 3, and between the guide roll 21 and the guide roll 22 and the guide roll 23. Two ion beam generators 6 and 7 are also arranged between the guide roll 24. It should be noted that at least one ion beam generator may be disposed along the outer peripheral surface of the water-cooled can roll 3.

And at the time of the normal rotation conveyance by which the strip | belt-shaped film board | substrate 16 is wound up by the 2nd roll 2 side from the 1st roll 1, with respect to the strip | belt-shaped film board | substrate 16 conveyed along the water-cooled can roll 3 outer peripheral surface, one sputtering cathode 4 is used. A film-shaped film substrate of a required amount (for example, the total amount of the band-shaped film substrate 16) is wound up by the second roll 2 while forming an oxide dielectric film layer (for example, a SiO ₂ film layer), and then the water-cooled can roll 3 When the belt-shaped film substrate 16 is transported in the reverse direction by reversing the rotation direction, a metal absorbing film layer (for example, a Ni alloy layer) is formed on the belt-shaped film substrate 16 transported along the outer peripheral surface of the water-cooled can roll 3 by the other sputtering cathode 5. In addition to film formation, a mixed ion beam of argon and oxygen is generated by the ion beam generator 8 and the ion beam generator 6 and this ion beam is generated. Winding by the first roll 1 while irradiating a part of the metal absorption film layer (for example, Ni alloy layer) after film formation with the on-beam, and then repeating these series of steps to absorb the oxide dielectric film layer and the metal absorption. An absorptive multilayer film in which film layers are alternately laminated can be formed on one side (surface) of the strip-shaped film substrate 16.

As shown in Table 1, in order to form the absorption multilayer film on both the front and back surfaces of the strip film substrate 16, the strip film substrate 16 having the absorption multilayer film formed on one surface (front surface) is removed from the second roll 2. And after winding around the 1st roll 1, reversing the front and back of the strip | belt-shaped film board | substrate 16, film-forming of the oxide dielectric film layer and metal absorption film layer which were mentioned above with respect to the back surface of the strip | belt-shaped film board | substrate 16 again. In addition, an absorption multilayer film in which the oxide dielectric film layer and the metal absorption film layer are alternately stacked may be formed by repeating each step of ion beam irradiation to the formed metal absorption film layer.
(4) Gradation density distribution In any of the first manufacturing apparatus and the second manufacturing apparatus described above, as shown in FIG. 3, a film substrate 15 on which a metal absorption film layer (for example, a Ni alloy layer) is formed, As 16 is conveyed, the ion beam 20 containing oxygen is oxidized while moving on the surface of the metal absorption film layer, and as a result, only the line portion irradiated with the ion beam 20 becomes transparent.

  When the line portion irradiated with the ion beam 20 of the metal absorption film layer and the periphery thereof are enlarged, the edge density of the transparent line portion becomes darker in the direction of the arrow as shown in FIG. Have a distribution. This is because there is a continuous difference in the degree of oxidation in the metal absorption film layer from the periphery of the ion beam 20 toward the center, and the metal absorption film layer from the periphery of the irradiated ion beam 20 toward the center. This is due to the continuous decrease in the extinction coefficient. And the circular area | region shown with the dotted line 30 in FIG. 4 can be utilized as an absorption type multilayer ND filter which has gradation density distribution.

  That is, the gradation density distribution is obtained by punching the region indicated by the dotted line 30 on the film substrates 15 and 16 having the absorption multilayer films formed on both the front and back surfaces using the first manufacturing apparatus and the second manufacturing apparatus. It is possible to obtain an absorption multilayer ND filter having the same.

  When the transmittance of the obtained absorption multilayer ND filter was measured at a wavelength of 550 nm corresponding to the distance from the center position of the irradiated ion beam, the result shown in the graph of FIG. 6 was obtained. It was. The ion beam radius at this time is 20 mm, but the transmittance continuously decreases between regions 20 mm to 30 mm away from the center position of the ion beam, and the ion beam is not irradiated and is not oxidized. It is confirmed that it has moved.

  Here, it is possible to change the gradation density distribution by appropriately adjusting the beam spreading shape in the ion beam to be irradiated and the distance between the film substrate and the ion beam, but if the power density of the ion beam is increased. The film substrate may melt. Further, a plurality of ion beam generators may be arranged side by side along the width direction of the film substrate to be conveyed. By arranging a plurality of ion beam generators along the width direction of the film substrate, a large number of boundary portions having a gradation density distribution can be produced at a time as shown in FIG. In addition, the ion beam includes a DC (direct current) ion beam and an RF (alternating current) ion beam. The ion beam can be condensed or diverged depending on the shape of the acceleration electrode. It is preferable to use an electrode.

Next, when forming an absorption type multilayer film on both front and back surfaces of the film substrate using the first manufacturing apparatus and the second manufacturing apparatus, ions to the metal absorption film layers formed on the front and back surfaces of the film substrate, respectively. By matching the beam irradiation positions, it is possible to manufacture an absorption type multilayer ND filter having a gradation gradation distribution of one level as shown in FIG. 8, and to form films on both the front and back surfaces of the film substrate. By shifting the irradiation position of the ion beam on the metal absorption film layer in the width direction of the film substrate, an absorption multilayer ND filter having a two-step gradation density distribution as shown in FIG. 9 can be manufactured.
(5) Manufacturing method of absorption multilayer ND filter Next, the manufacturing method of the absorption multilayer ND filter using the manufacturing apparatus of this invention is demonstrated. Although the second manufacturing apparatus (see FIG. 2) will be described as an example, the absorption multilayer ND filter can naturally be manufactured using the first manufacturing apparatus shown in FIG. .

a) Target In the second manufacturing apparatus shown in FIG. 2, a Ni or Ni alloy target is exemplified as a target for forming a metal absorption film, and SiO ₂ that is an oxide dielectric film is formed. The target is exemplified by a Si target.

In addition, Al ₂ O ₃ can be used instead of SiO ₂ as the oxide dielectric film, and TiO ₂ , Nb ₂ O ₃ , Ta ₂ O ₅ , HfO ₂ can be used to improve the wavelength dependency of optical characteristics. It is also possible to add ZrO ₂ .

  The metal absorbing film can be made of any material whose extinction coefficient is reduced by oxidation. In addition to the Ni or Ni alloy target described above, one kind selected from Ti, Ta, W, and Cr is used. Alternatively, these alloy targets can be used.

A target for forming the metal absorption film, for example, a Ni alloy target is formed by DC magnetron sputtering that introduces Ar gas, while a Si target for forming SiO ₂ that is an oxide dielectric film is The film is formed by dual magnetron sputtering introducing Ar gas, and the film is formed by controlling the amount of oxygen introduced by an impedance monitor in order to form SiO ₂ from the Si target.

  Further, a gas mixture of 50% argon and 50% oxygen is introduced into the ion beam generator, and irradiation is performed while adjusting the acceleration voltage. The ion beam generator may be attached at the position 6 or 8 in FIG.

b) Film substrate In the absorptive multilayer ND filter according to the present invention, the material of the film substrate is not particularly limited. Specific examples thereof include a resin film alone selected from resin materials such as polyethylene terephthalate (PET), polyethersulfone (PES), polyarylate (PAR), polycarbonate (PC), polyolefin (PO), norbornene, or the like. Examples thereof include a composite of a resin film alone selected from materials and an acrylic organic film covering one or both sides of this single body. In particular, as for the resin material of norbornene, representative examples include ZEONOR (trade name) manufactured by Nippon Zeon Co., Ltd. and Arton (trade name) manufactured by JSR Corporation.

c) Formation of Absorption-type Multilayer Film In the case where a Ni alloy target is used as a target for forming a metal absorption film and a Si target is used as a target for forming SiO ₂ that is an oxide dielectric film The film forming procedure of the absorption multilayer film will be described as an example.

1) The sputtering chamber 11 of the second manufacturing apparatus shown in FIG. 2 is evacuated to about 1 × 10 ⁻⁴ Pa.

    2) The film transport speed is adjusted, and the belt-shaped film substrate 16 is transported in the forward direction from the first roll 1 to the second roll 2 at, for example, about 1 to 5 m / min.

    3) Ar gas is introduced into the sputtering cathode 4 to which the Si target is attached, and sputtering is performed. Also, the oxygen introduction amount is controlled by an impedance monitor.

    4) Adjust the film speed and feed in the reverse direction.

    5) Ar gas is introduced into the sputtering cathode 5 to which the Ni alloy target is attached, and the Ni alloy film layer is oxidized by irradiating the ion beam with the ion beam generators 8 and 6 while performing sputtering.

    6) Adjust the film speed and transport in the forward direction.

    7) Ar gas is introduced into the sputtering cathode 4 to which the Si target is attached, and sputtering film formation is performed. Also, the oxygen introduction amount is controlled by an impedance monitor.

    8) Adjust the film speed and transport in the reverse direction.

    9) Ar gas is introduced into the sputtering cathode 5 to which the Ni alloy target is attached, and the Ni alloy film layer is oxidized by irradiating the ion beam with the ion beam generators 8 and 6 while performing sputtering.

  10) Adjust the film speed and transport in the forward direction.

  11) Ar gas is introduced into the sputtering cathode 4 to which the Si target is attached, and sputtering film formation is performed. Also, the oxygen introduction amount is controlled by an impedance monitor.

  12) Take out the belt-like film substrate 16 on which film formation on one side (front surface) has been completed, reverse the front and back and set it on the first roll 1, and repeat the steps 1) to 11) above to repeat the back side of the belt-like film substrate 16 Also, an absorption multilayer film is formed.

  13) The strip-shaped film substrate 16 having the absorption type multilayer film formed on both the front and back surfaces is taken out from the sputtering chamber 11.

  When transmittance measurement was performed at a wavelength of 550 nm corresponding to the distance from the center position of the ion beam of the band-shaped film substrate 16 having the absorption multilayer film formed on both the front and back surfaces, the result shown in the graph of FIG. 6 was obtained. It was. From the graph of FIG. 6, the transmittance changes linearly from about 90% to about 6% when the boundary portion between the portion where the oxidation of the Ni alloy film layer is advanced by the ion beam irradiation and the portion where the oxidation is not performed is observed. It is confirmed that there is an area. Therefore, an absorptive multilayer ND filter having a gradation density distribution can be obtained by punching this portion of the belt-like film substrate 16.

  Here, the gradation density distribution can be changed by appropriately adjusting the beam spreading shape in the ion beam to be irradiated and the distance between the belt-like film substrate and the ion beam. However, if the power density of the ion beam is increased, the film substrate may be melted. Therefore, it is necessary to adjust appropriately. A plurality of ion beam generators may be arranged side by side along the width direction of the belt-shaped film substrate to be conveyed. By arranging a plurality of ion beam generators along the width direction of the film substrate, a large number of boundary portions having a gradation density distribution can be produced at a time as shown in FIG.

  Moreover, when forming an absorption-type multilayer film on both front and back surfaces of a belt-like film substrate, the ion beam irradiation positions on the metal absorption film layers formed on both front and back surfaces of the film substrate are made to coincide with each other, as shown in FIG. In this way, it is possible to manufacture an absorption type multilayer ND filter having a gradation gradation distribution in one stage, and the ion beam irradiation position to the metal absorption film layer formed on each of the front and back surfaces of the film substrate is determined as the film substrate. By shifting in the width direction, an absorption-type multilayer ND filter having a two-step gradation density distribution as shown in FIG. 9 can be manufactured.

  Next, specific examples of the present invention will be described.

  First, a film structure (see Table 1) of an absorptive multilayer ND filter having an average transmittance of 6.3% at a wavelength of 400 to 700 nm was designed. FIG. 5 shows the spectral transmittance of the designed absorption multilayer ND filter. The spectral transmission characteristics of the ND filter were measured using a self-recording spectrophotometer (V570 manufactured by JASCO Corporation).

A sputtering roll coater, which is the second manufacturing apparatus shown in FIG. 2, is used to form the absorption multilayer film, and a Ni alloy target [Sumitomo Metal Mining Co., Ltd.] is used as a target for forming the metal absorption film. The Si target [manufactured by Sumitomo Metal Mining Co., Ltd.] was used as a target for depositing SiO ₂ which is an oxide dielectric film. The Ni alloy target is formed by DC magnetron sputtering that introduces Ar gas, while the Si target is formed by dual magnetron sputtering that introduces Ar gas, and an impedance monitor is used to form SiO ₂ from Si. The amount of oxygen introduced was controlled by a plasma emission monitor manufactured by Bon Ardennes.

  The ion beam generator was introduced with a mixed gas of 50% argon and 50% oxygen and irradiated at an acceleration voltage of 150 eV. The ion beam generator was attached at position 6 in FIG.

  The belt-like film substrate 16 was a PET film with a double-sided easy-adhesion layer (manufactured by Toyobo Co., Ltd.) having a thickness of 100 μm.

  Then, an absorption multilayer film was formed by the following procedure.

1) The sputtering chamber 11 of the second manufacturing apparatus shown in FIG. 2 was evacuated to about 1 × 10 ⁻⁴ Pa.

    2) The film transport speed was adjusted to 1.50 m / min, and the strip-shaped film substrate 16 was transported in the forward direction from the first roll 1 to the second roll 2.

3) Ar gas was introduced at 100 sccm into the sputtering cathode 4 to which the Si target was attached, and SiO ₂ was deposited at a sputtering output of 10 kW. The amount of oxygen introduced was controlled by an impedance monitor.

    4) The film speed was adjusted to 0.94 m / min and conveyed in the reverse direction.

    5) Ar gas was introduced at 100 sccm to the sputtering cathode 5 on which the Ni alloy target was mounted, and the Ni alloy film layer was formed at a sputtering output of 1 kW, while the ion beam was irradiated by the ion beam generator 6 to form the Ni alloy. The membrane layer was oxidized.

    6) The film transport speed was adjusted to 0.43 m / min, and the belt-shaped film substrate 16 was transported in the forward direction.

7) Ar gas was introduced at 100 sccm to the sputtering cathode 4 to which the Si target was attached, and a SiO ₂ film was formed at a sputtering output of 10 kW. The amount of oxygen introduced was controlled by an impedance monitor.

    8) The film speed was adjusted to 0.94 m / min and conveyed in the reverse direction.

    9) Ar gas was introduced at 100 sccm into the sputtering cathode 5 to which the Ni alloy target was attached, and the Ni alloy film layer was formed at a sputtering output of 1 kW, while the ion beam was irradiated by the ion beam generator 6 to form the Ni alloy. The membrane layer was oxidized.

  10) The film transport speed was adjusted to 0.46 m / min, and the belt-shaped film substrate 16 was transported in the forward direction.

11) Ar gas was introduced at 100 sccm into the sputtering cathode 4 to which the Si target was attached, and SiO ₂ was deposited at a sputtering output of 10 kW. The amount of oxygen introduced was controlled by an impedance monitor.

  12) Take out the belt-like film substrate 16 on which film formation on one side (front surface) has been completed, reverse the front and back and set it on the first roll 1, and repeat the steps 1) to 11) above to repeat the back side of the belt-like film substrate 16 Also, an absorption type multilayer film was formed.

  13) The strip-shaped film substrate 16 having the absorption multilayer film formed on both the front and back surfaces was taken out from the sputtering chamber 11.

  Then, when transmittance measurement was performed at a wavelength of 550 nm corresponding to the distance from the center position of the ion beam of the strip-shaped film substrate 16 having the absorption multilayer films formed on both the front and back surfaces, the result shown in the graph of FIG. 6 was obtained. Obtained. From the graph of FIG. 6, the transmittance changes linearly from about 90% to about 6% when the boundary portion between the portion where the oxidation of the Ni alloy film layer is advanced by the ion beam irradiation and the portion where the oxidation is not performed is observed. It is confirmed that there is an area. Therefore, an absorptive multilayer ND filter having a gradation density distribution can be obtained by punching this portion of the belt-like film substrate 16.

  Here, the gradation density distribution can be changed by appropriately adjusting the beam spreading shape in the ion beam to be irradiated and the distance between the belt-like film substrate and the ion beam. However, if the power density of the ion beam is increased, the film substrate may be melted. Therefore, it is necessary to adjust appropriately. A plurality of ion beam generators may be arranged side by side along the width direction of the belt-shaped film substrate to be conveyed. By arranging a plurality of ion beam generators along the width direction of the film substrate, a large number of boundary portions having a gradation density distribution can be produced at a time as shown in FIG.

  Moreover, when forming an absorption-type multilayer film on both front and back surfaces of a belt-like film substrate, the ion beam irradiation positions on the metal absorption film layers formed on both front and back surfaces of the film substrate are made to coincide with each other, as shown in FIG. In this way, it is possible to manufacture an absorption type multilayer ND filter having a gradation gradation distribution in one stage, and the ion beam irradiation position to the metal absorption film layer formed on each of the front and back surfaces of the film substrate is determined as the film substrate. By shifting in the width direction, an absorption-type multilayer ND filter having a two-step gradation density distribution as shown in FIG. 9 can be manufactured.

  The absorption multilayer ND filter according to the present invention having a gradation density distribution has industrial applicability for use in digital video cameras and the like.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic structure explanatory drawing of the 1st manufacturing apparatus based on this invention used for manufacture of the absorption type multilayer ND filter which has gradation density distribution. The schematic structure explanatory drawing of the 2nd manufacturing apparatus based on this invention used for manufacture of the absorption type multilayer ND filter which has gradation density distribution. Schematic explanatory drawing which shows the metal absorption film layer surface after being irradiated with the ion beam containing oxygen with an ion beam generator. FIG. 4 is a partial enlarged view in which a line portion irradiated with an ion beam on the surface of the metal absorbing film layer shown in FIG. 3 and a part of the periphery thereof are enlarged. The graph which shows the spectral transmittance of the absorption type multilayer ND filter which concerns on this invention. The graph which shows the relationship between the distance from the center of an ion beam, and the transmittance | permeability in the absorption type multilayer film obtained by irradiating the ion beam containing oxygen to a metal absorption film layer. Schematic explanatory drawing which shows the metal absorption film layer surface after ion beam irradiation was made when the several ion beam generator was arrange | positioned along the width direction of a film substrate. Explanatory drawing which shows 1 step gradation density distribution of the double-sided transmissivity in the absorption type multilayer film obtained when the irradiation position of the ion beam to each metal absorption film layer formed into film on both the front and back surfaces of the film substrate is matched. Two-step gradation density distribution of double-sided transmittance in absorption multilayer film obtained when ion beam irradiation position on each metal absorption film layer formed on both front and back sides of film substrate is shifted in width direction of film substrate FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st roll 2 2nd roll 3 Water cooling can roll 4 Sputtering cathode 5 Sputtering cathode 6 Ion beam generator 7 Ion beam generator 8 Ion beam generator 9 Ion beam generator 10 Load lock chamber 11 Sputtering chamber 12 Ion beam generator DESCRIPTION OF SYMBOLS 13 Sputtering cathode 14 Sputtering cathode 15 Sheet-like film substrate 16 Strip | belt-shaped film substrate 20 Ion beam 21 Guide roll 22 Guide roll 23 Guide roll 24 Guide roll 30 Dotted line

Claims (10)

An absorption type multilayer film comprising an oxide dielectric film layer and a metal absorption film layer alternately laminated on at least one surface of a film substrate, and the absorption type multilayer film has a gradation density distribution. In the multilayer ND filter,
The oxide dielectric film layer and the metal absorption film layer are formed by sputtering, and each metal absorption film layer is irradiated with an ion beam containing oxygen after the sputtering film formation so that the transmittance of the irradiated portion is not irradiated. It is higher than the area, and the extinction coefficient of the metal absorption film layer continuously decreases from the periphery to the center of the irradiated ion beam, and the irradiation area has a gradation density distribution. An absorption multilayer ND filter characterized by the above. A sputtering chamber equipped with a vacuum pump;
A single unit provided adjacent to the sputtering chamber and accommodates a plurality of sheet-like film substrates, and allows the sheet-like film substrate to be taken into and out of the sputtering chamber without opening the sputtering chamber to the atmosphere. Or a pair of load lock chambers,
The sheet-like film substrate is held and carried from the load lock chamber to the sputtering chamber, and the conveyance direction of the sheet-like film substrate carried in the sputtering chamber is conveyed in a reversible manner, and the film is processed in the sputtering chamber. And a plurality of holders for carrying the film-like film substrate to the same or other load lock chambers,
In the sputtering chamber, two sputtering cathodes and an ion beam generator are arranged along the conveying direction of the sheet film substrate, and a target for forming an oxide dielectric film layer is attached to one of the sputtering cathodes. On the other side, a target for forming a metal absorption film layer is attached,
An oxide dielectric film layer and a metal absorption film layer are sequentially formed by a sputtering cathode on a sheet-like film substrate transported in a sputtering chamber, and a mixed ion beam of argon and oxygen is generated by an ion beam generator. The ion beam is irradiated onto a part of the metal absorption film layer after the film formation, and the oxide dielectric film layer and the metal absorption film layer are formed and formed while the conveying direction of the sheet-like film substrate is reversed. Gradation density distribution characterized by forming an absorption multilayer film in which an oxide dielectric film layer and a metal absorption film layer are alternately laminated by repeating each step of ion beam irradiation to the formed metal absorption film layer An apparatus for manufacturing an absorption-type multilayer ND filter. A sputtering chamber equipped with a vacuum pump;
A first roll and a second roll which are provided in the sputtering chamber to wind and unwind the belt-like film substrate, a can roll which is provided in a transport path between the first roll and the second roll and on which the belt-like film substrate is wound; Two sputtering cathodes provided along the outer peripheral surface of the can roll and at least one ion beam generator;
A target for forming an oxide dielectric film layer is attached to one of the sputtering cathodes, and a target for forming a metal absorption film layer is attached to the other,
The second roll or the first roll while forming the oxide dielectric film layer with one sputtering cathode on the belt-like film substrate unwound from the first roll or the second roll and conveyed along the outer peripheral surface of the can roll After the necessary amount of the belt-shaped film substrate is wound up by the above, the other sputtering cathode with respect to the belt-shaped film substrate that is conveyed along the outer peripheral surface of the can roll with the rotation directions of the first roll, the second roll, and the can roll reversed. The metal absorbing film layer is formed by the above method, and a mixed ion beam of argon and oxygen is generated by the ion beam generator, and the first roll or the second roll is applied while irradiating a part of the metal absorbing film layer after the film formation. Winding with two rolls, and then repeating these series of steps, the oxide dielectric film layer and the metal absorption film layer were alternately laminated. Absorption type multi-layer film ND filter manufacturing apparatus having a gradated density distribution and forming a Osamugata multilayer film.   A plurality of guide rolls are provided between the first roll and the can roll and between the second roll and the can roll, respectively, and the first roll side guide roll and the second roll side guide roll are conveyed to the belt-like film substrate. And an ion beam generator for irradiating an ion beam containing oxygen, respectively, between the guide roll on the first roll side and the sputtering cathode and between the guide roll on the second roll side and the sputtering cathode on the outer peripheral surface of the can roll. 4. The production apparatus for an absorption multilayer ND filter according to claim 3, wherein an ion beam generator for irradiating an ion beam containing oxygen to the belt-shaped film substrate conveyed along the belt film substrate is provided.   The apparatus for producing an absorption multilayer ND filter according to any one of claims 2 to 4, wherein a plurality of ion beam generators are provided side by side along the width direction of the film substrate to be conveyed. A method of manufacturing an absorption multilayer ND filter having a gradation density distribution using the manufacturing apparatus according to claim 2,
A first step of holding the sheet-like film substrate accommodated in the load lock chamber with a holder;
A second step of bringing the sheet-like film substrate held by the holder into the evacuated sputtering chamber;
An oxide dielectric film layer and a metal absorption film layer are sequentially formed by two sputtering cathodes on the sheet-like film substrate conveyed in the sputtering chamber, and a mixed ion beam of argon and oxygen is produced by an ion beam generator. And a third step of irradiating a part of the metal absorption film layer after film formation with this ion beam,
Reversing the conveying direction of the sheet-like film substrate, the sheet is formed by repeating the process of forming the oxide dielectric film layer and the metal absorption film layer and the ion beam irradiation on the formed metal absorption film layer as necessary. A fourth step of forming an absorptive multilayer film on the surface of the film substrate;
The sheet-like film substrate with the absorption multilayer film formed on the surface is carried out to the same or another load lock chamber, and the sheet-like film substrate is turned upside down in the load lock chamber, and then this sheet-like film substrate is used as a holder. And a fifth step for carrying it into the sputtering chamber,
A sixth step of forming the absorptive multilayer film on the back surface of the sheet-like film substrate by repeating the third step and the fourth step in the sputtering chamber;
Gradation of sheet-like film substrate with absorption multilayer film formed on the back side is carried out to the same or other load-lock chamber, and sheet-like film substrate with absorption multilayer film is formed on the front and back surfaces. A seventh step of obtaining an absorption-type multilayer ND filter having a concentration distribution;
The manufacturing method of the absorption type multilayer ND filter characterized by comprising. A method of manufacturing an absorption multilayer ND filter having a gradation density distribution using the manufacturing apparatus according to claim 3,
A first step of setting the strip film substrate on the first roll or the second roll in the sputtering chamber;
After evacuating the sputtering chamber, the belt-shaped film substrate set on the first roll or the second roll is transported along the outer peripheral surface of the can roll while unwinding, and one of the sputtering provided along the outer peripheral surface of the can roll A second step of winding with a second roll or a first roll while forming an oxide dielectric film layer with a cathode;
After the winding of the belt-like film substrate to the second roll or the first roll is completed, the belt-like film is conveyed along the outer peripheral surface of the can roll with the rotation directions of the first roll, the second roll and the can roll reversed. A metal absorption film layer is formed on the substrate by the other sputtering cathode, and a mixed ion beam of argon and oxygen is generated by an ion beam generator, and this ion beam is irradiated to a part of the metal absorption film layer after film formation. While the third step of winding with the first roll or the second roll,
The above-described oxide dielectric film layer and metal absorption film layer are formed, and the treatment using the ion beam irradiation as a unit to the formed metal absorption film layer is repeated as many times as necessary to form an absorption type multilayer film on the surface of the belt-like film substrate. A fourth step to be formed;
A fifth step of wrapping the first roll or the second roll while removing the band-shaped film substrate having the absorption multilayer film formed on the surface from the first roll or the second roll and inverting the front and back of the band-shaped film substrate;
After evacuating the sputtering chamber, the front and back sides are reversed, and the second to fourth steps are repeated on the belt-like film substrate wound around the first roll or the second roll. A sixth step of forming a film;
A seventh step of obtaining an absorptive multilayer ND filter having a gradation density distribution by punching a band-shaped film substrate having an absorptive multilayer film formed on the front and back surfaces;
The manufacturing method of the absorption type multilayer ND filter characterized by comprising.   The irradiation position of the ion beam to the metal absorption film layer formed on the front and back surfaces of the sheet-like film substrate or the belt-like film substrate is shifted in the width direction between the front and back surfaces of the sheet-like film substrate or the belt-like film substrate. The method for producing an absorption multilayer ND filter according to claim 6 or 7, wherein:   9. The method of manufacturing an absorption multilayer ND filter according to claim 6, 7 or 8, wherein the metal absorption film layer is made of a material whose extinction coefficient is reduced by oxidation.   10. The method for producing an absorption multilayer ND filter according to claim 9, wherein the material whose extinction coefficient is reduced by oxidation is Ni or a Ni alloy.

Images