CN110724913A - A large-diameter mirror resistance thermal evaporation coating device - Google Patents

Abstract

The invention belongs to the field of vacuum coating, and provides a large-diameter mirror resistance thermal evaporation coating device. The technical scheme provided by the present invention is: including a vacuuming system and a vacuuming system, a vacuum evaporation chamber, an evaporation source chamber, an ion beam auxiliary device, and a film thickness control device; the evaporation source chambers are a plurality of independent evaporation source chambers, which are evenly arranged On the chamber wall of the vacuum evaporation chamber, a vacuum valve is arranged between each evaporation source chamber and the vacuum evaporation chamber; the workpiece rotation device is arranged at the bottom center of the vacuum evaporation chamber, and the workpiece rotation device is supported by a mirror support mechanism It is composed of a rotary shaft 10 and a rotary motor; the ion beam auxiliary device is composed of a plurality of ion sources and is arranged on the inner wall of the vacuum evaporation chamber cavity. The use of the device of the invention avoids the influence of metal droplet sputtering, dripping, etc. on the quality of the film layer, and greatly reduces the risk in the process of coating large-diameter mirrors.

Description

A large-diameter mirror resistance thermal evaporation coating device

technical field

The invention relates to the field of vacuum coating, and is particularly suitable for a large-diameter mirror resistance thermal evaporation coating device.

Background technique

The development of telescopes has extended the limits of human vision, allowing humans to appreciate the vastness of the universe and laying the foundation for the continuous progress of astronomy. For an optical system, the resolution of the system depends on the size of the clear aperture. The larger the clear aperture, the higher the resolution of the optical system. The aperture of the astronomical telescope has gradually developed from the initial 4.2cm to 2.4m or even 8.4m. To meet the requirements of observing more distant targets and obtaining clearer images, breakthroughs have been made in the manufacturing capabilities of large-diameter optical components and rapid development has been achieved.

Reflecting telescopes are the most widely used type of large-aperture optical systems, and large-aperture mirrors are one of the key elements in large-scale reflective optical systems. The optical performance of large-diameter mirrors depends on the performance of the reflective film coated on the reflective surface of the mirror body. The metal reflective film is simple, the preparation process is relatively low, and the working wavelength range is wide, which can achieve a very high reflectivity under a wide working wavelength, which satisfies the design and use requirements of large-diameter optical systems to the greatest extent. Therefore, metal high-reflection films have been widely used in large-diameter optical systems currently used.

The film material commonly used to prepare metal reflective films is aluminum, because aluminum has a high reflectivity in a wide band, and its surface rapidly forms a dense Al ₂ O ₃ protective film in the air to prevent further corrosion of Al. destroy. The aluminum high-reflection film has a reflectivity of about 90% in the visible to near-infrared band.

At present, most of the aluminum high-reflection films are prepared by thermal evaporation deposition technology. However, in the process of coating large-diameter mirrors, if the top-loading method is used, that is, the coating of the mirror faces downwards, the mirror is too large and heavy. In the process of mirror coating, it is necessary to perform reversal and hoisting. These operations have the problems of difficulty in implementation and increased manufacturing cost. At present, there is also a bottom-mounted method, that is, a coating method with the mirror facing up. However, in this method, since the evaporation source is on the top, the sputtering and dripping of the evaporation material will seriously affect the quality of the film layer, and even cause the mirror to be damaged.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a large-diameter mirror resistance thermal evaporation coating device to overcome the problems in the prior art that the operation is difficult to implement, the manufacturing cost increases, and the coating quality is difficult to guarantee when the bottom is installed.

To achieve the above object, the present invention provides the following technical solutions:

A large-diameter mirror resistance thermal evaporation coating device, comprising a vacuum system 1 and a vacuum system 2, a vacuum evaporation chamber 3, an evaporation source chamber, an ion beam auxiliary device, and a film thickness control device; the evaporation source chamber is: A plurality of independent evaporation source chambers 4, the plurality of evaporation source chambers 4 are evenly arranged on the chamber wall of the vacuum evaporation chamber 3, and a vacuum valve 5 is arranged between each evaporation source chamber 4 and the vacuum evaporation chamber 3; the workpiece The rotating device is arranged at the bottom center of the vacuum evaporation chamber 3, and the workpiece rotating device is composed of a mirror support mechanism 9, a rotating shaft 10 and a rotating motor 11; on the inner wall of the evaporation chamber cavity.

The number of the above-mentioned multiple evaporation source chambers is 3-9.

The above-mentioned evaporation device of the evaporation source chamber is composed of a heating electrode 6 and a heating boat 7 .

The above heating boat is tungsten stranded wire.

The above-mentioned ion source 8 for the ion beam assisting device is uniformly distributed on the cavity wall of the vacuum evaporation chamber, and emits the ion beam downward.

The above-mentioned film thickness control device uses a quartz crystal film thickness meter 12 .

The above-mentioned rotary electric machine 11 is a stepping motor.

Compared with the prior art, the beneficial effects of the present invention are:

1. The present invention adopts the down-loading method, the structure is reasonable, and the risk of mirror reversal is reduced;

2. Since the coating state is consistent with the processing and use state of the reflector, the reflecting surface is upward, which reduces the influence of gravity deformation on the surface shape accuracy of the large-diameter reflector when it is hoisted and supported by suspension;

3. Due to the separation of the vacuum evaporation chamber and the evaporation source chamber, although the down-loading method is adopted, the influence of metal droplet splashing and dripping on the quality of the film can be avoided;

Description of drawings

FIG. 1 is a schematic structural diagram of the front view of the device of the present invention.

Among them: vacuum system 1, vacuum system 2, vacuum evaporation chamber 3, evaporation source chamber 4, vacuum valve 5, heating electrode 6, heating boat 7, ion source 8, mirror support mechanism 9, rotating shaft 10, step Into the motor 11, quartz crystal film thickness gauge 12.

FIG. 2 is a schematic top view of the structure of the device of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be completely described below with reference to the accompanying drawings in the embodiments of the present invention, and the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present invention.

As shown in Figures 1-2, in the embodiment of the present invention, a large-diameter mirror resistance thermal evaporation coating device includes a vacuum system 1, a vacuum system 2, and a vacuum evaporation chamber 3. The vacuum system 1 passes through pipes and The vacuum evaporation chamber 3 is connected for evacuating the vacuum evaporation chamber 3. The vacuum evaporation chamber 3 is used to install the large-diameter reflector to be plated. The cavity wall of the vacuum evaporation chamber 3 is evenly distributed with 3 - 9 smaller evaporation source chambers 4, the vacuum evacuation system 2 is connected to a plurality of uniformly distributed evaporation source chambers 4 through pipes, and is used for vacuuming the plurality of evaporation source chambers at the same time, and the vacuum evaporation chamber 3 It is connected with the evaporation source chamber 4, and a corresponding number of vacuum valves 5 are arranged between the vacuum evaporation chamber and the evaporation source chamber. For the heating of the film material; the ion beam auxiliary device is composed of a plurality of ion sources 8, and is installed on the inner wall of the vacuum evaporation chamber cavity, used for ion beam assisted deposition and bombardment of film material molecules or molecules, to the film material. A downward kinetic energy of molecules or atoms; the workpiece rotating device is composed of a mirror support mechanism 9 , a rotating shaft 10 and a stepping motor 11 ; the film thickness control device adopts a quartz crystal film thickness gauge 12 .

In the preparation stage before coating, the vacuum evaporation chamber and the evaporation source chamber are inflated to the atmospheric state, the vacuum valve 5 is opened, the film material is first loaded on the evaporation system of the multiple evaporation source chambers, and then the vacuum valve 5 is closed, and the large-diameter mirror is coated Push it up into the vacuum evaporation chamber, and do a good job of positioning and fixing. Close the chamber door of the vacuum evaporation chamber, open the vacuum pumping system 1 and the vacuum pumping system 2, and pump the vacuum evaporation chamber and the evaporation source chamber to a high vacuum state respectively.

During the evaporation process, the workpiece (large-diameter mirror) rotating motor 11 and ion source 8 are first turned on, and the large-diameter surface is bombarded with ion beams before coating, and the film material in the evaporation source chamber 4 is heated at the same time. After the film material is melted, the vacuum valve 5 is opened. At this time, a part of the film material molecules in the evaporation source chamber 4 will move to the bottom of the vacuum evaporation chamber 3. In addition, because the air pressure in the vacuum evaporation chamber 3 is lower than that of the evaporation chamber 3 The air pressure in the source chamber 4 and the film material molecules in the evaporation chamber will also accelerate the movement to the plated surface of the large-diameter mirror under the action of the pressure difference and the bombardment of the ion beam, and finally form a thin film on the surface of the large-diameter mirror. The film thickness control device is used to control the thickness of the film to be plated.

The working principle of the present invention is as follows: when the large-diameter reflector adopts the bottom-mounted method, that is, the coating film faces upward, the vacuum evaporation chamber is separated from the evaporation source chamber, and a vacuum valve is provided, so that the evaporation source chamber can be The film material is first heated and evaporated. Since each point on the tungsten wire of the heating device can be regarded as a point evaporation source, when the vacuum valve is opened, a part of the film material molecules or atoms will naturally be transported directly to the surface of the mirror and form a film. In addition, under the action of the pressure difference between the evaporation source chamber and the vacuum evaporation chamber and the bombardment of the ion beam, some molecules or atoms of the film material transported in other directions will also be transported to the surface of the mirror and form a film.

Claims (7)

1. a large-diameter mirror resistance thermal evaporation coating device, comprising a vacuum system 1 and a vacuum system 2, a vacuum evaporation chamber 3, an evaporation source chamber, an ion beam auxiliary device, a film thickness control device; it is characterized in that: all The evaporation source chambers described are a plurality of independent evaporation source chambers 4, and the plurality of evaporation source chambers 4 are evenly arranged on the chamber wall of the vacuum evaporation chamber 3, and a vacuum is set between each evaporation source chamber 4 and the vacuum evaporation chamber 3. Valve 5; the workpiece rotating device is arranged at the bottom center of the vacuum evaporation chamber 3, and the workpiece rotating device is composed of a mirror support mechanism 9, a rotating shaft 10 and a rotating motor 11; the ion beam auxiliary device is composed of a plurality of ion sources 8 components, which are arranged on the inner wall of the vacuum evaporation chamber cavity. 2 . The large-diameter mirror resistance thermal evaporation coating device according to claim 1 , wherein the number of the plurality of evaporation source chambers is 3-9. 3 . 3 . The large-diameter mirror resistance thermal evaporation coating device according to claim 1 or 2 , wherein the evaporation device in the evaporation source chamber is composed of a heating electrode 6 and a heating boat 7 . 4 . 4 . The large-diameter mirror resistance thermal evaporation coating device according to claim 3 , wherein the heating boat is a tungsten stranded wire. 5 . 5. The large-diameter mirror resistance thermal evaporation coating device according to claim 3, wherein the ion source 8 for the ion beam auxiliary device is evenly distributed on the cavity wall of the vacuum evaporation chamber, and is directed toward the ion source 8 of the ion beam auxiliary device. emitting the ion beam. 6 . The large-diameter mirror resistance thermal evaporation coating device according to claim 3 , wherein the film thickness control device adopts a quartz crystal oscillator film thickness gauge 12 . 7 . 7 . The large-diameter mirror resistance thermal evaporation coating device according to claim 3 , wherein the rotating motor 11 is a stepping motor. 8 .

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