JP2580419B2 - Manufacturing method of lightweight reflector base - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a reflector for use in astronomical observation, beam focusing, or the space industry, for example. The present invention relates to a method for manufacturing a reflector base having improved structural strength and optical characteristics.

[0002]

2. Description of the Related Art Conventionally, astronomical reflectors and high energy beams have been used.
For example, a reflecting mirror used for optically condensing a film or the like is made of, for example, a metal vapor-deposited film of aluminum or the like as an optical reflecting layer on the surface of a bubble-free reflecting mirror plate made of quartz glass or high silica made of lath or the like. Is formed, and this is supported on the operation support base to be freely rotated. Such a reflecting mirror base is required to maintain accuracy without being affected by the temperature of the reflecting surface or an internal force change. Such reflectors have hitherto been 5 mm in diameter.
Although small ones having a diameter of about 20 cm have been the mainstream, large ones having a diameter of 30 cm to 1 m or more have been required in recent years in order to obtain a high light collection rate, and have come into practical use.
However, since such a large one becomes extremely heavy, deformation due to its own weight occurs due to a change in the supporting attitude such as the supporting angle of the reflecting mirror, or a swelling phenomenon occurs on the mirror surface, thereby reducing the optical performance of the reflecting mirror. There were problems such as lowering.

[0003] With such an increase in size, mirror surface undulations and the like change due to subtle changes in volume and deformation of the reflector base due to radiation of the condensing beam and changes in environmental temperature. Therefore, quartz glass or high silicate glass having a small thermal expansion change without such a phenomenon has come to be used as a material for a reflector. But,
Since these glasses make the reflector base heavy and reduce the operability of the reflector, it is required that the base be reduced as much as possible to improve the operability. In line with such practical requirements, many proposals have been made to achieve sufficient supporting strength and weight reduction, particularly for a supporting member for a large reflector plate.

For example, Japanese Patent Publication No. 63-57761 discloses a light-weight reflector material for a celestial body, which has a support grid made of several rows of tubes, such as quartz glass, between a transparent reflector plate (front plate) and a rear plate. Each tube of the tube row is staggered so as to have a contact line or contact zone with two tubes of an adjacent row, and the thickness of the tube wall in the area of the contact line or the like is such that the remainder of the wall A special tube structure is disclosed in which the tubes are welded together along contact lines and the like. However, the astronomical reflector material having such a special configuration has a complicated configuration, is not easily manufactured, and is extremely disadvantageous industrially. Further, such a reflector material has a remarkably low strength in the surface direction of the reflector, and cannot be said to be a satisfactory supporting member for polishing the curved surface of the integrated reflector plate.

Further, in such a reflector material, it is difficult to make the effective height of the tube material, which is a support grid, strictly constant at the time of manufacture, and therefore, the tube material is not uniform on the laminated transparent reflector plate. The unevenness remains as a distortion, which causes a temporal change such as swelling of the mirror surface at a later date, which is a major factor in lowering the performance of the reflecting mirror. Also, due to its structure, when the mirror surface is horizontal and vertical with respect to gravity, the rigidity against its own weight changes and the surface accuracy changes slightly depending on the mirror surface, so the posture is movable. However, it is difficult to use for applications that require operability.

Japanese Patent Publication No. 61-26041 relates to a lightweight mirror, and more particularly, it is made of quartz glass between a front plate and a rear plate made of quartz glass and fixed to these plates so as not to move. A lightweight mirror for celestial bodies in which a support grid is fused and integrated. The support grid is composed of a plate-like member made of quartz glass and / or a tubular member placed on a supporting plate, and a granular material, a small tube, or the like is placed in a space left between the two members. The material to be sintered, consisting of pieces, small particles, platelets, etc., or a mixture thereof, is filled and the arrangement is held together by graphite rings, which are then placed in a furnace under a non-oxidizing atmosphere. It is also disclosed that the support grid, which is heated to the sintering temperature and is so formed, is fixedly connected to the front and rear plates by heat fusion.

However, in this method, a large number of plate-like members or tubular members having an appropriate shape are prepared in advance, and a predetermined space arranged in parallel is filled with a sintering material, or a reinforcing tubular member filled with a sintering material is filled. Since it requires troublesome operation, labor, and time for appropriately arranging the front plate and the rear plate and fusing the front plate and the rear plate, it is difficult to industrially adopt the method. In addition, the method using this tubular member is insufficient in weight reduction, and the flat plate is difficult to polish because the portion of the front plate for the reflector to which the tubular support member is fused is distorted, and optical precision is impaired. Problem.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a practically desirable lightweight reflector base which is excellent in operability and does not cause distortion in the reflector surface due to a temperature change or the like. . Another object is to provide a highly practical foamable porous support member that is lightweight and has excellent three-dimensional strength in a direction orthogonal to the support direction of the reflector plate as a support member for the reflector plate. Yet another object is to provide an industrially advantageous method of manufacturing such a lightweight reflector base.

[0009]

SUMMARY OF THE INVENTION The gist of the present invention is a method of manufacturing a lightweight reflector base comprising the constituent elements described in the claims of the present specification, in particular, claim 1.

The reflecting mirror is a reflecting mirror which collects and scatters light, for example, sunlight and laser beams, and is particularly useful for astronomical objects and the space industry. It can also be used for condensing or utilizing solar heat, and the reflective surface of the silicon oxide transparent bubble-free plate forming the mirror surface is formed into a curved surface according to the purpose of use. In addition, an appropriate metal film is formed on the surface according to the type of light to be used. Regardless of the method of use, the reflecting mirror is required to have high optical reflection accuracy and easy operability. Therefore, it is important that the reflecting surface is made of a material that does not substantially deform due to a temperature change. Is used.

In the method of the present invention, the member supporting such a reflector plate is preferably a quartz glass or a high silicate glass made of at least 99% by weight of silicon oxide and has an apparent density of 0.1 to 1 g. / Cm ³ is used. When the apparent density of the porous foam is less than 0.1 g / cm ³ , the supporting strength for supporting the reflector plate is weak, and when it exceeds 1 g / cm ³ , the weight reduction is insufficient,
The tendency of deformation due to its own weight increases, and satisfactory operability cannot be obtained.

It is important that such a foam is mainly composed of closed cells. Since a porous body having a high closed cell content has a network having a three-dimensional lattice structure, it has excellent compressive strength in all directions. That
Therefore , since such a porous foam uniformly supports the reflecting mirror plate over the entire surface, the porous foam has excellent resistance to the pressing force applied to the reflecting mirror plate surface during polishing, and is directed in a direction parallel to the surface. It is extremely desirable as a holding member for a reflector plate because it provides excellent resistance strength.

The apparent density used in the method of the present invention is 0.1
For example, a quartz glassy or high silicate glassy porous foam layer having a thickness of １1 g / cm ³ is formed by, for example, reacting a hydroxyl group-containing quartz glass powder made of silicon oxide with ammonia in an ammonia atmosphere under heating. Molding and sintering into a desired shape, or molding and sintering are heated and reacted in an ammonia atmosphere to produce an ammoniated sintered body, and then, for example, the sintered body is heated to 1500 to 1800 ° C. in an electric furnace. It can be produced by a gas which is heated and melted to a temperature and released from the glass at that time, and a foam mainly composed of closed cells is effectively obtained.

Further, it can also be manufactured by mixing a powder which reacts and sublimates at a predetermined temperature into a silica powder and heat-fuses it. In the production of these heated foams,
In addition to forming a foam having a suitable diameter and a porous foam made of quartz glass or high silicate glass having an apparent density of 0.1 to 1 g / cm ³ , the heating and foaming conditions are set so as to prevent the formation of open cells due to excessive heating. Selected.

The above-mentioned porous foam layer preferably has an apparent density of 0.1 to 1 g / cm ³ in order to satisfy the strength and light-weight operability as a substrate for a reflector, and has an apparent density of 0.1 to 1 g / cm ^3.
If it is less than 0.1 g / cm ³ , the degree of imaginaryness as a reflector base is insufficient, and if it exceeds 1 g / cm ³ , the weight reduction is insufficient and the operability of the reflector deteriorates, which is not preferable.

The porous foam produced in this manner is appropriately cut into a desired shape, for example, a disk or a square plate, according to the size and shape of the reflector, and one surface of the porous foam is used for the reflector. A plate made of transparent non-bubble quartz glass or high silicate glass is fused to the other surface, and a plate made of quartz glass or high silicate glass not requiring high purity is fusion-bonded to the other surface. In this unifying operation, between the upper surface of the porous foam layer and the back surface of the reflecting mirror disk, and between the lower surface of the porous foam layer and quartz glass or high silicate glass. A curable silicone adhesive is applied between and interposed between the upper surface of the plate and interposed to maintain such a bonded state,
For example, by heating to a temperature of about 100 to 400 ° C. for about 30 to 100 minutes, a strong heat-resistant adhesive structure can be obtained.

According to this integration method, the porous foam layer, the reflector plate and the bottom plate are firmly joined to each other at a relatively low temperature at which the reflector plate and the porous foam layer do not deform, Easily formed into lightweight reflectors. In this joining, as is clear from the joining operation, the joining surface of the plate to be joined to the surface of the porous body is formed in advance in a surface shape so as to contact substantially the entire surface.

The reflector plate to be fused and integrated on one surface of the foam layer is a transparent plate made of quartz glass or high silicate glass having as high a purity as possible and substantially containing no bubbles. Body. Even if this reflection plate contains fine bubbles, it brings an undesirable state such as distortion or distortion to the reflection surface,
It is not preferable because a highly accurate reflecting mirror cannot be produced. Also, the bottom plate that is melted and integrated with the other surface is
It is not necessary to have high purity and transparency like a reflector plate, and it is possible to include some bubbles or the transparency may be impaired, but quartz glass or high silicate glass that does not substantially affect temperature changes It is important that the plate is made of quality.

In the method of the present invention, after the two plates are integrally joined to the foam layer as described above, a seal layer is formed on the entire peripheral side surface of the laminate. The Sea
Prior to the formation of the Le layers, the entire circumferential surface is, for example, a grinder - rather preferably be smooth finished by a method such as shrink finishing by fire, such as a smooth polished or hydrogen oxygen combustion flame by, then, the peripheral side surface over the entire surface It is very important to form a seal layer by applying a heat-resistant curable silicone resin to the resin and curing it.

Although this airtight seal does not always require high airtightness, it has been found that it is important to obtain a high degree of flat polishing finish in the subsequent precision smooth polishing of the surface of the reflector plate. . If there was no seal, a satisfactory flat surface could not be obtained by precision polishing. Although the reason is not clear, it is conceivable that in water-based polishing, subtle effects on fine polishing of the surface can be attained by negligible fine powdered abrasive or water entering each interface between the porous foam layer of the substrate and the upper and lower plates. As a result, it is considered that it becomes difficult to form an optically excellent reflection film of vapor-deposited aluminum metal or silver.

In the method of the present invention, it is important that the heat-resistant silicone adhesive used for joining and integrating the laminate is curable at room temperature, preferably thermosetting. Silicon having sufficient resistance to temperature of ℃
Resin. In the method of the present invention , a silicone resin having two or more silanol groups SiOH in one molecule is used as such a silicone adhesive.
You .

In the laminated body whose peripheral side surface is hermetically sealed, the surface of the upper transparent non-bubble reflecting mirror surface forming plate is flat or predetermined by a commonly known precision polishing method using, for example, an aqueous abrasive. The surface of the mirror is highly polished to a high precision, and the light reflecting mirror substrate of the present invention is finished. Then, a metal film for the reflecting mirror such as aluminum or silver is formed on the surface by vapor deposition or other known means. Finished as a large reflector.

[0023]

According to the method of the present invention, a light-weight base body on which a flat or curved mirror having a stable and excellent optical surface accuracy is formed on a reflecting mirror surface can be effectively provided. In addition, the large reflector obtained by the method of the present invention has excellent structural strength despite its light weight, and its high-precision mirror surface is stably maintained over a long period of time. And its industrial practical value is extremely high.

[0024]

Now, the present invention will be described in further detail with reference to specific examples. Example 1 Silicon tetrachloride was supplied to an oxyhydrogen flame burner and flame-hydrolyzed to produce a quartz glass soot body, which was reacted with ammonia gas at a temperature of 1000 ° C. for 2 hours, and then an ammonia atmosphere was produced. The gas was expelled and heated to a temperature of 1600 ° C. to form a foam, and a quartz glass porous foam having an apparent density of about 0.3 g / cm ³ was obtained. This foam was cut into a disk with a diameter of 350 mm and a thickness of 25 mm.

On the front surface of the porous disk, a transparent and bubble-free quartz glass disk for a reflecting mirror having a diameter of 350 mm and a thickness of 0.5 mm is provided.
Also, on the rear surface (lower surface), the rear plate has a diameter of 500 mm and a thickness of 0.5
mm quartz glass discs are bonded together, and each bonded surface is heated through a heat-resistant silanol-based silicone resin adhesive layer to a temperature of about 300 ° C. for about 1 hour while maintaining the bonded state. The adhesive was cured to bond and integrate the components. In the structure obtained in this way, the porous foam layer and the bubble-free transparent quartz glass plate are uniformly bonded and integrated over the entire surface, so distortion occurs in the quartz glass plate due to uneven bonding and light reflection occurs. There is no disadvantage of deteriorating the characteristics, and the reflecting surface is not deformed or damaged even when stress such as pressing during polishing is applied, and has sufficient strength as a lightweight reflector base. there were.

Next, the surface of the foam layer exposed on the peripheral side surface of this structure is smoothly ground and polished with a grinder over the entire periphery, and the peripheral side surface is cured with a room temperature-curable silicone rubber-based sealing agent. To form an airtight seal layer. The surface of the transparent non-bubble quartz glass plate of the structure having the peripheral side airtightly sealed in this way was precisely polished using an aqueous polishing liquid, and the flatness of the surface was examined by optical interference fringes. The interference fringes were parallel, and it was confirmed that the entire surface had extremely high flatness. The precision polished surface provides an excellent reflecting surface for laser light or the like by forming an aluminum vapor-deposited film thereon. Accordingly, the structure thus precisely polished is extremely desirable as a lightweight reflector base having much better optical characteristics than conventionally known lightweight reflectors.

[0027]

According to the method of the present invention, the weight of the porous support is smaller than that of the conventionally known large-sized reflector base.
Provided is a reflecting mirror having excellent three-dimensional pressing strength and optically high precision by metal deposition. In addition, the lightweight reflector has excellent operability even in a large one, and the practical value as a large reflector for celestial bodies is extremely high. Furthermore, since the substrate obtained by the method of the present invention is provided at a much lower cost than that of a conventional similar reflector substrate,
It is extremely advantageous industrially.

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-61-151501 (JP, A) JP-A-52-40349 (JP, A) JP-B-61-26041 (JP, B2)

Claims (1)

(57) [Claims] [Claim 1] have a apparent density 0.1 to 1 g / cm ^3, primary
A transparent glass-free quartz glass or high silicate glass reflector plate is provided on one side of a quartz glass or high silicate glass porous foam layer composed of closed cells, and quartz glass or high silicate glass is provided on the other side. Each silicate glass plate in each molecule is 2
Bonding with a curable silicone adhesive having at least two silanol groups (SiOH) for heat integration , and coating a heat-resistant curable silicone resin over the entire peripheral surface.
A method for manufacturing a lightweight reflector base, which comprises: cloth, hardening , sealing the peripheral side surface airtightly, and then precisely polishing the surface of the transparent bubble-free plate.