CN110456434B - Reflecting mirror capable of inhibiting surface dust and preparation method thereof - Google Patents
Reflecting mirror capable of inhibiting surface dust and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/08—Oxides
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
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- C23C14/086—Oxides of zinc, germanium, cadmium, indium, tin, thallium or bismuth
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- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/10—Glass or silica
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
- C23C14/24—Vacuum evaporation
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- G02B1/16—Optical coatings produced by application to, or surface treatment of, optical elements having an anti-static effect, e.g. electrically conducting coatings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/08—Mirrors
- G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/28—Reflectors in projection beam
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Abstract
The invention discloses a reflector capable of inhibiting surface dust and a preparation method thereof. The substrate is optical plastic or optical glass, and the reflector consists of a titanium dioxide film and a silicon dioxide film. The ITO film has a thickness of about 30nm and is provided on the outermost layer of the mirror in the air. The thickness of the ITO film is monitored to be a maximum reflectivity value by a reflection pole method. And closing the vacuum chamber to bake after the film coating is finished, cooling for 40 minutes, annealing, and then exhausting. The ultra-short focal length mirror coated with the ITO film has excellent performance of inhibiting surface dust. Thereby preventing the accumulation of dust on the surface of the mirror in the optical system for ultra-short focus projection display as much as possible.
Description
Technical Field
The invention relates to the technical field of optical films, in particular to a reflector capable of inhibiting surface dust and a preparation method thereof.
Background
The color gamut coverage rate of laser display in a projection system can reach more than 90% of the color space which can be identified by human eyes, is more than twice of the traditional display color gamut coverage rate, thoroughly breaks through the defect of the color gamut space of the previous third generation display technology, and is the mainstream direction of the future display technology. Since the conventional projection system has problems of image interference, space limitation, and the like, and the reduction of the projection ratio is undoubtedly the most effective way to solve the problem at present, the design and application of the ultra-short-focus system embody its importance.
The application and the function of the reflector in the ultra-short focus are as follows: the ultra-short focus projection system takes red, green and blue laser as an illumination light source, the three-color laser enters a display chip through a lens, a DM filter (medium light splitting filter), a compound eye, a PBS (polarization beam splitter prism) and the like, emergent light of the display chip enters a projection lens, and the emergent light of the projection lens is reflected by a reflector and an aspheric surface reflecting bowl and then irradiates a desktop. The picture projected by the lens in the ultra-short focus projection system can be displayed in the reflector, the 45-degree inclination angle of the reflector can reflect the whole imaging picture to the non-spherical reflection bowl, and the light rays are reflected by the reflection bowl and then project the appointed picture on the desktop.
The important reflector in the ultra-short focus system has the problem of obvious surface dust accumulation in the using process of the system, thereby not only reducing the image brightness, but also reducing the image definition and influencing the imaging effect. One of the important reasons for the deposition of dust on the mirror surface is the presence of electrostatic accumulation on the mirror surface. Since optical glass or optical plastic substrates, and the thin film materials of mirrors, titanium dioxide and silicon dioxide, are dielectric materials, or non-conductive insulating materials, the surfaces of these materials are highly susceptible to electrostatic accumulation effects. This daily unnoticeable build-up of static electricity can constantly attract dust from the air to deposit on the mirror surfaces, resulting in a reduction in the reflectivity and resolution of the mirror, and in turn, a reduction in not only the brightness of the image, but also the sharpness of the image.
Disclosure of Invention
In order to overcome the problem of dust accumulation on the surface of the reflector, the invention provides the reflector capable of inhibiting the dust on the surface and the preparation method thereof.
The present invention is intended to introduce an "antistatic" conductive film into a mirror to prevent the electrostatic accumulation effect, thereby achieving the purpose of suppressing the accumulation of dust on the surface of the mirror due to the electrostatic accumulation effect.
The invention provides a reflector capable of inhibiting surface dust and an ultra-short-focus projector. The ITO conductive film has the advantages of good conductivity, high visible light transmittance, good processability and the like, and is widely applied to the fields of smart phones, tablet computers, display devices and the like. The ITO conductive film can inhibit the dust accumulation problem on the surface of the reflector caused by the electrostatic accumulation effect under the condition of not obviously influencing the reflectivity of the reflector.
The concept of the invention is as follows: first, the electrostatic build-up is mainly due to the lack of conductivity of the mirrors. Since the substrate of the mirror is usually optical glass or optical plastic and the thin film of the mirror surface is usually a dielectric material, all of these substrate materials and thin film materials are good insulators, it is naturally understood that the mirror surface forms a static charge accumulation. Second, it is the most effective method to make the mirror conductive, and the simplest method to make the mirror conductive is to plate a metal film. However, the metal film has a large absorption and a low reflectance, and for example, for the most commonly used aluminum film, the absorption in the visible region is about 9%, that is, the reflectance cannot exceed 91%, and the firmness, surface, and stability are insufficient, so that it is preferable to select a semiconductor conductive film. The semiconductor film has a larger absorption than the dielectric film but a much smaller absorption than the metal film, and the film has satisfactory robustness and stability. Again, many alternative semiconductor films include indium oxide (In) 2 O 3 ) Film, tin oxide (SnO) 2 ) Films, zinc oxide (ZnO) films or indium tin oxide (In) 2 O 3 ·SnO 2 ) Films, and the like. Studies on these films have shown that indium tin oxide films are most suitable in view of a combination of conductivity, low absorption and high transmission, stability and ease of manufacture. The Indium Tin Oxide film is actually a Tin-doped Indium Oxide film having a doping ratio of Tin Oxide to Indium Oxide = 9: 91, and this film is often referred to simply as an ITO film (abbreviation of Indium Tin Oxide). The ITO film has an energy band width of 3.5eV or more and a carrier electron density of 10 20 ～10 21 cm -3 Is a compound with a mobility of 10-30 cm 3 ·V -1 ·s -1 The specific substance group of (1). Since the average energy of photons of visible light is about 3.1eV, the thin film material cannot cause intrinsic excitation under the irradiation of the visible light, and therefore, the transmittance in the visible light range is high. In the deposition process of the thin film, the process conditions have a significant influence on the visible light transmittance. ITO film prepared at low or room temperature using indium tin alloy targetGenerally lower visible light transmittance. The reason is mainly because black suboxides InO and SnO are generated, and the thin film shows the characteristics of metal. The low-valence oxide can be further oxidized to generate high-valence oxide through heat treatment or high-temperature deposition, and the transmittance of the film is obviously improved.
The ITO thin film in the transparent conductive oxide film has high visible light transmittance (about 90%) and infrared reflectance, and low resistivity (1 × 10) -4 cm～4×10 -4 cm), abrasion resistance, and good mechanical strength and chemical stability. In order to reduce the absorption of the ITO film as much as possible and increase the reflectivity of the reflecting film, the invention limits the film thickness of the ITO film to about 30nm. In order to further reduce the absorption of the ITO film and to ensure the convenience of preparation, the ITO film is arranged at the outermost layer of the reflecting mirror film close to the air, namely the reflecting mirror film is S | (HL) 10 H'(0.78L0.78H) 7 0.78L0.78 (H 'ITO) | Air outermost layer high refractive index film H' and ITO film jointly synthesize 1/4 wavelength, in the above film system structure, S represents the substrate, H is high refractive index titanium dioxide (TiO) 2 ) Film, L is silicon dioxide (SiO) with low refractive index 2 ) Film, H 'and H' are both high refractive index film layers TiO the same as H 2 However, since the thickness is different, it is represented by H' or H "to distinguish them. (HL) 10 Film thickness control wavelength of lambda 1 ＝650nm，(0.78L0.78H) 7 The film thickness control wavelength of 0.78L0.78 (H' ITO) is lambda 2 Film thickness control wavelength of =507nm, H' is lambda 3 ＝(λ 1 +λ 2 ) And/2 =578.5nm, and since all the film layers are 1/4 wavelength thickness of the specific control wavelength, the thickness of each film layer can be monitored by using a photoelectric extreme value control method. Then, because the resistivity depends on the substrate temperature during film coating to a certain extent, the higher the substrate temperature is, the lower the resistivity is, in order to reduce the absorption and increase the conductivity as much as possible and reduce the resistivity, the ITO film is subjected to evaporation under the conditions of a base temperature of 300 ℃, an oxygen pressure of 150sccm and an evaporation rate of 2 nm/min, and the thickness of the ITO film is monitored to a maximum value of the reflectivity by a reflection electrode method so as to accurately achieve the thickness required by the ITO. Finally, in order to improve the current carrier concentration of the ITO film and further improve the conductivity of the ITO film, the film coating is finishedThen the vacuum chamber is closed to bake, the film is cooled for 40 minutes, the annealing treatment is carried out, and then the gas is discharged, thus finishing the film coating.
The technical scheme adopted by the invention for solving the technical problems is as follows:
a reflector capable of inhibiting surface dust comprises a substrate and a dielectric reflector film layer arranged on the substrate, wherein an indium tin oxide film (ITO film) is arranged on one side, close to air, of the dielectric reflector film layer, and the dielectric reflector film layer is composed of high-refractive-index films and low-refractive-index films which are alternated.
The indium tin oxide film is a film composed of tin oxide and indium oxide at a mass ratio of 9: 85-95, more preferably, the indium tin oxide film is a film composed of tin oxide and indium oxide at a mass ratio of 9: 89-93, and most preferably, the indium tin oxide film is composed of tin oxide and indium oxide at a mass ratio of 9: 91.
The substrate is optical plastic or optical glass.
The high refractive index film is a titanium dioxide film, and the low refractive index film is a silicon dioxide film.
The dielectric reflector film layer is 30-45 layers, the indium tin oxide film layer is 1 layer, and the total number is 31-46 layers. More preferably, the dielectric mirror film layer is 35-39 layers, the indium tin oxide film layer is 1 layer, and the total number of the layers is 36-40 layers. Most preferably, the dielectric mirror film layer is 37 layers, the indium tin oxide film layer is 1 layer, and the total number is 38 layers.
From the substrate to the outside, the 1 st, 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th, 15 th, 17 th and 19 th layers are titanium dioxide films with the thickness of 67.99nm, and the 2 nd, 4 th, 6 th, 8 th, 10 th, 12 th, 14 th, 16 th, 18 th and 20 th layers are silicon dioxide films 3 with the thickness of 111.57nm;
the 21 st layer is a titanium dioxide film with the thickness of 67.99nm;
the 22 th, 24 th, 26 th, 28 th, 30 th, 32 th, 34 th and 36 th layers are silicon dioxide films, the 23 th, 25 th, 27 th, 29 th, 31 th, 33 th, 35 th and 37 th layers are titanium dioxide films with the thickness of 53.07nm, the thickness of 87.02nm, the 38 th layer is an indium tin oxide film with the thickness of 30nm.
The reflecting mirror is composed of a titanium dioxide film with a high refractive index and a silicon dioxide film with a low refractive index, the number of the reflecting mirror layers is 38, wherein the 37 th high refractive index film and the 38 th ITO film are synthesized into a quarter wavelength;
the doping ratio of the ITO film (indium tin oxide film) is tin oxide to indium oxide =9 to 91.
Further, the thickness of the ITO film is about 30nm.
Further, the ITO film is arranged on the side, close to the air, of the dielectric reflector film layer, namely the outermost position close to the air.
An ultra-short focus projector adopts the reflector which can inhibit surface dust. Thereby preventing the accumulation of dust on the surface of the mirror in the optical system for ultra-short focus projection display as much as possible.
A method for manufacturing a reflector capable of suppressing surface dust, comprising the steps of:
a dielectric reflector film layer is firstly prepared on a substrate, and then an indium tin oxide film (ITO film) is evaporated to obtain the reflector capable of inhibiting surface dust.
The conditions for evaporating the indium tin oxide film (ITO film) are as follows: the evaporation is carried out at a substrate temperature of 250 to 350 ℃, an oxygen pressure of 100 to 200sccm and a stable evaporation rate of 1 to 3 nm/min, more preferably at a substrate temperature of 280 to 320 ℃, an oxygen pressure of 130 to 170sccm and a stable evaporation rate of 1.8 to 2.2 nm/min, and most preferably at a substrate temperature of 300 ℃, an oxygen pressure of 150sccm and a stable evaporation rate of 2 nm/min.
In order to improve the carrier concentration of the ITO film and further improve the conductivity of the ITO film, the vacuum chamber is closed and baked after the indium tin oxide film (ITO film) is evaporated, the cooling is carried out for 30 to 50 minutes, the annealing treatment is carried out, and then the gas is discharged, and further preferably, the vacuum chamber is closed and baked after the indium tin oxide film (ITO film) is evaporated, the cooling is carried out for 35 to 45 minutes, the annealing treatment is carried out, and then the gas is discharged, most preferably, the vacuum chamber is closed and baked after the indium tin oxide film (ITO film) is evaporated, the cooling is carried out for 40 minutes, the annealing treatment is carried out, and then the gas is discharged.
Because the 37 th layer of titanium dioxide film with high refractive index and the 38 th layer of ITO film are combined into a quarter wavelength, the thickness of the ITO film can be monitored to the maximum value of the reflectivity by a reflection pole method so as to ensure that the thickness of the ITO film is about 30nm.
In order to obtain good ITO thin film conductivity, different film thicknesses and resistivity are mainly controlled, and mature film system design and a film coating process are important means for accurately controlling the film thickness and the resistivity. The thickness of the film layer can be accurately simulated through the design of the film system, and the real realization of the simulation is that the deposition rate and the deposition time are controlled through a mature film coating process to obtain the specified film thickness.
Compared with the prior art, the invention has the beneficial effects that:
according to the current projection market, the laser projector is a future development trend to replace the traditional mercury lamp projector, and the ultra-short-focus projector has the advantages of saving space, and being convenient for a user to operate and watch pictures by gestures when being projected on a desktop. The ultra-short-focus projection has a very good prospect in future projection markets, particularly in places such as education, offices and the like.
The dust-proof treatment of the reflector of the ultra-short-focus projector is an important problem which needs to be solved, because the reflector used in the imaging process can continuously gather dust, which has serious influence on the finally projected picture. To address this problem, the existing solutions are to seal the entire structure and reduce the intrusion of external dust. However, since the ultra-short focus projector needs to dissipate heat by air cooling, the projector cannot be completely sealed. In addition, no matter the projector is blown or exhausted, air flow inside and outside the ultra-short-focus projector is caused, and dust is brought into the projector. If static electricity is accumulated on the surface of the reflector, dust can be continuously accumulated on the surface of the reflector, and the final projection picture is influenced.
The invention avoids static accumulation by carrying out ITO film coating on the surface of the reflector, thereby solving the problem of dust accumulation. The dust removal device is simple and effective in practical application, does not need to be connected with an external structure, does not influence other parts of the ultra-short-focus projector, and completely depends on the structure and relevant characteristics of the dust removal device to achieve the purpose of dust removal.
Drawings
FIG. 1 is a schematic diagram of an ITO film of an ultra-short-focus mirror capable of suppressing surface dust according to the present invention;
FIG. 2 is a reflectance spectroscopy curve for a prior art mirror used at a 45 angle;
FIG. 3 is a reflectance spectroscopy curve for a mirror of the present invention in use at a 45 angle;
FIG. 4 is a film thickness control curve of the outermost H' film and ITO film of the ultra-short focus mirror of the present invention.
Detailed Description
FIG. 1 is a schematic diagram of an ITO film of an ultra-short-focus mirror capable of suppressing surface dust according to the present invention. In an ultra-short-focus projection display system, the reflecting mirror usually comprises a plane reflecting mirror, an aspheric reflecting mirror and the like, but no matter the reflecting mirror is a plane reflecting mirror or an aspheric reflecting mirror, as shown in fig. 1, the reflecting mirror capable of suppressing surface dust comprises a substrate 1 and a dielectric reflecting mirror film layer arranged on the substrate 1, an indium tin oxide film 4 (ITO film) is arranged on one side of the dielectric reflecting mirror film layer close to air, and the dielectric reflecting mirror film layer is formed by alternately forming a titanium dioxide film 2 with a high refractive index and a silicon dioxide film 3 with a low refractive index. The indium tin oxide film 4 is composed of tin oxide and indium oxide at a mass ratio of 9: 91. The substrate 1 is an optical plastic or an optical glass. The film system structures of the invention are basically the same, specifically: s | (HL) 10 H'(0.78L0.78H) 7 0.78L0.78 (H' ITO) | Air, in the film system structure, S represents a substrate, and H is titanium dioxide (TiO) with high refractive index 2 ) Film, L is silicon dioxide (SiO) with low refractive index 2 ) Film, H 'and H' are high refractive index TiO of the same material and different thickness 2 And (3) a membrane. Because the reflector is used in large angle, the reflecting band is narrowed because the reflecting band of p-polarized component is narrowed, at this time, it is impossible to cover the visible light region by using a reflecting film stack, so that it is necessary to connect at least two reflecting film stacks in series to attain the goal of said ultra-short focal reflector reflecting band. In the above film system structure, (HL) 10 Is a first reflective film stack having a film thickness controlled at a wavelength of λ 1 =650nm, achieving high reflection at the long wavelength end of the visible region; (0.78L0.78H) 7 0.78L0.78 (H' ITO) is a second reflective film stack, and the film thickness is controlled to have a wavelength of λ 2 The wavelength is not less than 507nm, and high reflection at the short wave end of a visible light region is realized; however, since only the two reflective film stacks are connected in series and a transmission band occurs in the connection region, it is necessary to insert a high refractive index film layer H' having a film thickness controlled to have a wavelength equal to the average wavelength of the two reflective film stacks, i.e., λ 3 ＝(λ 1 +λ 2 ) /2=578.5nm. It can be seen that since all layers are 1/4 wavelength thick at a particular control wavelength, the thickness of each layer can be monitored by photoelectric extremum control. The last remaining problem is that the outermost high-refractive-index H' film relying on air and the ITO film are jointly synthesized into a 1/4 wavelength film, so that the position in the film system structure is determined for the ITO film, and at the position, the ITO film not only has the best effect of inhibiting dust agglomeration, but also has little influence on the reflectivity, and more importantly, the preparation is simple and convenient. Specifically, after optimization, the dielectric mirror film layer is 37 layers, the indium tin oxide film 4 is 1 layer, and the total number is 38 layers. From the substrate 1 to the outside, the 1 st, 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th, 15 th, 17 th and 19 th layers are titanium dioxide films 2 with the thickness of 67.99nm, and the 2 nd, 4 th, 6 th, 8 th, 10 th, 12 th, 14 th, 16 th, 18 th and 20 th layers are silicon dioxide films 3 with the thickness of 111.57nm; the 21 st layer is a titanium dioxide film with the thickness of 67.99nm; the 22 nd, 24 th, 26 th, 28 th, 30 th, 32 th, 34 th and 36 th layers are silicon dioxide films 3, the 23 th, 25 th, 27 th, 29 th, 31 th, 33 th, 35 th and 37 th layers are titanium dioxide films 2 with the thickness of 53.07nm, the thickness of 87.02nm, the 38 th layer is an indium tin oxide film 4 with the thickness of 30nm.
Fig. 2 is a reflectance profile of a prior art mirror when used at a 45 angle. Only in terms of the ultra-short focal reflector, the reflector structure in the prior art is not much different from the reflector structure in the invention, and the high refractive index lambda at the outermost part close to the air side is mainly used 2 /4TiO 2 Layer is changed into lambda 2 /4(TiO 2 + ITO) layer, fig. 3 is the reflectance spectroscopy curve for the inventive mirror when used at a 45 angle. Comparing fig. 2 and fig. 3, it can be seen that the reflection bandwidth and the reflectivity of the two structures are actually very different, and under the condition of the same layer number and the same incident angleThe average reflectance of the prior art mirror in the wavelength region 430nm to 660nm of FIG. 2 is 99.8%, while the average reflectance of the inventive mirror in the wavelength region 430nm to 660nm of FIG. 3 is 98.8%, which is a slight difference from the ITO film because the refractive index of the ITO film is higher than that of TiO 2 Low film at wavelength λ 2 ＝507nm，TiO 2 The refractive index of the film is about 2.39 and the refractive index of the ITO film is only 1.89, which reduces the average refractive index of the air-side outermost quarter wave film, while the higher the refractive index of the air-side outermost quarter wave film, the greater the contribution to the improvement in reflectivity, which is why the average reflectivity of the mirror of the present invention is slightly reduced. This means that the invention replaces the conductivity of the reflector with the sacrifice of 1% average reflectivity, and obtains the effect of automatically inhibiting the dust accumulation of the reflector, and eliminates a great trouble problem in the using process of the reflector. Compared with a common reflector, the reflector for ultra-short focus projection, whether a plane reflector or an aspheric reflector, is mainly characterized in that a reflection band needs to cover a visible light region, and the used incidence angle is larger; furthermore, because they are all located in the imaging optical path, the requirements on the aberration and cleanliness of the reflecting surface are extremely high, and the reflector is extremely large, the manufacturing difficulty and the price are high, which also indicates the value of the ultra-short focus reflector of the invention.
It has been pointed out that since all the film layers of the ultra-short-focus mirror of the present invention are 1/4 wavelength thick with specific control wavelength, the thickness of each film layer can be easily and conveniently monitored by using the photoelectric extremum control method, but the outermost high refractive index film depending on air is now a 1/4 wavelength film composed of a high refractive index H "film and an ITO film, which brings difficulty to the thickness control of the H" film and the ITO film. FIG. 4 is a film thickness control curve of the H' film and the ITO film during the preparation of the ultra-short focus mirror of the present invention. H (TiO) film if not coated with ITO film 2 ) Optical thickness of the layer should be lambda 2 /4=126.75nm, due to λ 2 ＝507nm，TiO 2 The refractive index of the film was about 2.39, so the actual physical thickness was 53nm; at present, an H' film and an ITO film are required to be jointly synthesized into a 1/4 wavelength film, and H ″ (TiO) is calculated when the thickness of the ITO film is 30nm 2 ) The physical thickness of the film was also 30nm, so the reflectance of the H "film was calculated to be 18.9%. Thus, only need to replace K before plating 9 The surface reflectivity of the monitoring piece is 4.2 percent, and TiO is evaporated 2 At a control wavelength lambda 2 When the reflectance gradually increased from 4.2% to 18.9%, it was indicated that the thickness of the H "film reached 30nm, and deposition was stopped immediately. Because (H' + ITO) jointly synthesizes lambda 2 And 4, the physical thickness of the ITO film is 30nm only by controlling the reflectivity of the ITO film to reach a maximum value of 24 percent, and the whole evaporation process is completed. The conditions for depositing an indium tin oxide film (ITO film) were as follows: the evaporation was carried out at a substrate temperature of 300 deg.C, an oxygen pressure of 150sccm and a stable evaporation rate of 2 nm/min. In order to improve the carrier concentration of the ITO film and further improve the conductivity of the ITO film, after the indium tin oxide film 4 (ITO film) is evaporated, the vacuum chamber is closed to bake, the ITO film is cooled for 40 minutes, annealing treatment is carried out, and then air is discharged.
The reflector prepared by the method has the resistivity of 3 multiplied by 10 at the outermost layer position depending on air -4 Omega cm or less, the conductivity is better, has destroyed the static accumulation effect, therefore has excellent characteristic of inhibiting the surface dust. In addition, the average reflectivity of the reflector in the wavelength range of 430 nm-660 nm is 98.8%, and the reflector has important application value in projection display technology and various optical systems.
Claims (3)
1. A reflector capable of inhibiting surface dust comprises a substrate and a dielectric reflector film layer arranged on the substrate, and is characterized in that an indium tin oxide film is arranged on one side, close to air, of the dielectric reflector film layer, and the dielectric reflector film layer is composed of high-refractive-index films and low-refractive-index films which are alternated;
the substrate is optical plastic or optical glass;
the high refractive index film is a titanium dioxide film, and the low refractive index film is a silicon dioxide film;
the indium tin oxide film consists of tin oxide and indium oxide in a mass ratio of 9: 91;
the dielectric reflector film layer is 37 layers, the indium tin oxide film layer is 1 layer, and the total number is 38 layers;
from the substrate to the outside, the 1 st, 3 rd, 5 th, 7 th, 9 th, 11 th, 13 th, 15 th, 17 th and 19 th layers are titanium dioxide films with the thickness of 67.99nm, and the 2 nd, 4 th, 6 th, 8 th, 10 th, 12 th, 14 th, 16 th, 18 th and 20 th layers are silicon dioxide films with the thickness of 111.57nm;
the 21 st layer is a titanium dioxide film with the thickness of 67.99nm;
the 22 th, 24 th, 26 th, 28 th, 30 th, 32 th, 34 th and 36 th layers are silicon dioxide films, the 23 th, 25 th, 27 th, 29 th, 31 th, 33 th, 35 th and 37 th layers are titanium dioxide films with the thickness of 53.07nm, the thickness of 87.02nm, the 38 th layer is an indium tin oxide film with the thickness of 30nm.
2. The method of claim 1, comprising the steps of:
firstly preparing a dielectric reflector film layer on a substrate, and then evaporating an indium tin oxide film to obtain a reflector capable of inhibiting surface dust;
the conditions for evaporating the indium tin oxide film are as follows: carrying out evaporation plating by adopting the conditions of substrate temperature of 250-350 ℃, oxygen pressure of 100-200 sccm and stable evaporation rate of 1-3 nm/min;
closing the vacuum chamber to bake after the indium tin oxide film is evaporated, cooling for 30-50 minutes, annealing, and then discharging gas.
3. The method for producing a mirror capable of suppressing surface dust according to claim 2, wherein the conditions for depositing the indium tin oxide film are as follows: carrying out evaporation plating by adopting the conditions of substrate temperature of 280-320 ℃, oxygen pressure of 130-170 sccm and stable evaporation rate of 1.8-2.2 nm/min;
closing the vacuum chamber to bake after the indium tin oxide film is evaporated, cooling for 35-45 minutes, annealing, and then discharging gas.
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| CN1804664A (en) * | 2005-01-14 | 2006-07-19 | 索尼株式会社 | Optical device, transmission lens, image pickup device and electronic device |
| CN101029937A (en) * | 2006-03-02 | 2007-09-05 | 富士胶片株式会社 | Optical film, anti-reflection film, polarizing plate and image display device |
| DE102011084269A1 (en) * | 2011-10-11 | 2013-04-11 | Evonik Degussa Gmbh | Process for the preparation of polymer nanoparticle compounds by means of a nanoparticle dispersion |
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| CN1804664A (en) * | 2005-01-14 | 2006-07-19 | 索尼株式会社 | Optical device, transmission lens, image pickup device and electronic device |
| CN101029937A (en) * | 2006-03-02 | 2007-09-05 | 富士胶片株式会社 | Optical film, anti-reflection film, polarizing plate and image display device |
| DE102011084269A1 (en) * | 2011-10-11 | 2013-04-11 | Evonik Degussa Gmbh | Process for the preparation of polymer nanoparticle compounds by means of a nanoparticle dispersion |
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