JPH11199256A - Joined optical element and formation of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a high precision joined optical element having no flaw and no crack. SOLUTION: This method comprises subjecting a surface having a final shape of a first optical element 3 and the opposite surface to a surface having a final shape of a second optical element 4 to press joining together to form the objective joined optical element, wherein the material temp. of the optical element 3 is adjusted to a temp. that is equal to or lower than the transition point of the optical element 3 and by >=10 deg.C higher than the transition point of the second optical element 4; and the material temp. of the second optical element 4 is adjusted to a temp. that is equal to or lower than the transition point of the second optical element 4 and by <=300 deg.C lower than the material temp. of the optical element 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic optical element such as a synthetic lens in which optical elements made of different materials are press-molded with a molding die and joined, and a method of molding the same.

[0002]

2. Description of the Related Art Conventionally, a synthetic optical element such as a synthetic lens or a synthetic prism used in a photographing optical system or the like is obtained by bonding a plurality of optical elements obtained by cutting and polishing or press molding using an adhesive. It is manufactured by. At this time, high-precision processing of the bonding surface before bonding and centering of a plurality of optical elements are extremely complicated and highly difficult operations,
Further, since it is difficult to accurately adjust the shape of the joint surface except for the spherical surface, there is a problem that there is no design freedom.

On the other hand, a method of molding a synthetic optical element by fusing and joining glass is known. For example, Japanese Patent Application Laid-Open No. 60-67118 discloses a method of forming a first optical element between upper and lower molds.
The optical element and the material of the second optical element are arranged, and the material of the second optical element is press-molded at a temperature at which the material of the second optical element can be formed and the material of the first optical element is not deformed. 2
A method of forming a combined optical element by integrating the above optical elements is disclosed.

[0004]

However, in the method of the above-mentioned conventional example of Japanese Patent Application Laid-Open No. 60-67118, the first and second optical elements are molded at a single temperature. The material of the second optical element exceeds the transition point even at a temperature at which the material of the first optical element does not deform. In particular, when the material is glass, the first and second optical elements are joined at such a temperature because the thermal expansion coefficient is in an abnormal expansion temperature range where the thermal expansion coefficient sharply increases at the transition point. In a state where the material of the first optical element is not deformed, only the material of the second optical element has an abnormal expansion temperature range and is subjected to press molding.

For this reason, during cooling, the difference between the thermal expansion coefficients of the materials of the first and second optical elements becomes large, and the amount of contraction of the material of the second optical element is reduced by the amount of contraction of the material of the first optical element. The amount is much larger than the amount, and a large stress is generated at a joint portion between the two, and the molded product is easily cracked. Especially,
In the case where the first optical element is a diffraction grating having fine irregularities, there is a problem that the irregularities form notches and cracks are more likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a synthetic optical element for forming a synthetic optical element by fusing and joining different glasses to each other without cracking during molding, and a method of molding the same.

[0007]

A composite optical element according to the present invention for achieving the above object is a composite optical element formed by joining first and second optical elements made of two different materials. The material temperature of the first optical element is maintained at a temperature equal to or lower than its transition point and at least 10 ° C. higher than the transition temperature of the material of the second optical element, and the material temperature of the second optical element is maintained at the same. 30% below the transition point and above the first material temperature
The second optical element having a non-joining surface formed in a final shape is pressure-bonded to the first optical element formed in a final shape while being held without lowering the temperature by 0 ° C. or more.

Further, in the method for molding a synthetic optical element according to the present invention, the first and second optical elements having different materials may be arranged such that the material temperature of the first optical element is equal to or lower than its transition point and the second In the method of forming a composite optical element by pressing and bonding the first and second optical elements to a temperature higher than the transition point of the optical element, The transition point is set to be equal to or higher than the transition point near the junction with the first optical element and not to exceed the transition point in other portions.

Further, a method of molding a synthetic optical element according to the present invention is a method of manufacturing a synthetic optical element by joining first and second optical elements made of two kinds of materials, wherein The material temperature of the optical element is maintained at a temperature equal to or lower than its transition point and at least 10 ° C. higher than the transition point of the material of the second optical element, and the material temperature of the second optical element is maintained at a temperature equal to or lower than the transition point of the material. The first optical element formed in a final shape and the second optical element formed in a non-bonded surface in a final shape are held by holding without lowering the temperature of the first material by 300 ° C. or more. To form a combined optical element.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. 1 and 2 are sectional views of a molding apparatus for a synthetic optical element according to the first embodiment. FIG. 1 shows a state before molding, and FIG. 2 shows a state during molding. The molding apparatus comprises an upper mold 1 having a convex surface and a lower mold 2 having a concave surface.
Is mounted on the lower mold 2, and a transfer robot 5 for transferring the second optical element 4 on the first optical element 3 is provided. Further, the synthetic optical element 6 shown in FIG.
Indicates a state in which the first optical element 3 and the second optical element 4 are pressure-bonded.

As a glass material, the first material of the first optical element 3 is LaK12 (nd = 1.67990, νd = 5).
4.9, Tg = 562 ° C., At = 593 ° C.)
The second material of the second optical element 4 is LAM69 (nd = 1.
73077, νd = 40.6, Tg = 497 ° C., At =
529 ° C).

Prior to molding of the composite optical element, the first material is made of LaK12 with an outer diameter of 2 using an apparatus (not shown).
The first optical element 3 having a shape of 8 (mm), a center thickness of 8, a convex surface R20, and a concave surface R58 is formed. After the molding and cooling are completed, only the upper mold 1 is replaced with the concave R43 mold from the concave R58 mold, and the lower mold 2 is reheated with the first optical element 3 as a molded article placed thereon. The reheating condition was 497 ° C for the upper mold 1,
The temperature of the lower mold 2 is 562 ° C., so that the material of the first optical element 3 on the lower mold 2 is also heated to 562 ° C.

Next, a second optical element 4 having an outer diameter 28, a center thickness 4, a convex surface R55, and a concave surface R43 is formed by cutting and polishing using a second material LAM69. Then, the second optical element 4 is placed in another place in the molding apparatus.
Heated to 97 ° C., transported and placed on the first optical element 3 by the transport robot 5, and further lowered the upper mold 1 to press-bond the first optical element 3 and the second optical element 4. I do. Immediately after joining, cooling is performed to prevent unnecessary temperature rise of the second optical element 4.

By the above-described steps, the combined optical element 6 is formed. The composite optical element 6 is free from cracks and cracks, and good quality is obtained.

Table 1 shows the results of the joining performed by changing the temperature conditions by the above method.

Table 1 First material Lower mold temperature Second material Upper mold temperature Joining result 1 562 ° C. 562 100 100 First material cracked 2 562 562 262 262 262 OK 3 562 562 497 497 OK 4 562 562 507 507 Second material Cracking 5 507 507 100 100 Cracking of the first material 6 507 507 207 207 OK 7 507 507 497 497 OK 8 507 507 507 507 Cracking of the second material 9 497 497 497 497 Insufficient deformation of the second material 10 572 572 572 497 First material deformed

FIGS. 3 and 4 are sectional views of the apparatus for molding a synthetic optical element according to the second embodiment. FIG. 3 shows a state before molding and FIG. 4 shows a state at the time of molding. The molding apparatus is composed of a flat upper mold 7 and a lower mold 8, and a first optical element 9 having a diffraction pattern formed on the surface thereof is mounted on the lower mold 8. A transport robot 11 for transporting the second optical element 10 is provided on 9. 4 shows a state in which the first optical element 9 and the second optical element 10 are pressure-bonded.

As a glass material, SK12 is used as the first material.
(Nd = 1.68313, vd = 59.4, Tg = 50
6 ° C, At = 538 ° C) and SF8 as the second material.
(Nd = 1.69320, vd = 33.7, Tg = 45
6 ° C., At = 508 ° C.).

Prior to this molding, an outer diameter of 30 and a thickness of 5 are formed using SK12 as a first material by a molding device (not shown).
Then, the flat first optical element 9 having a diffraction pattern formed on one side is formed. Separately, using SF8 for the second material,
The second optical element 10 is formed by cutting and polishing a flat plate having an outer diameter of 30 and a thickness of 2.

The first optical element 9 is placed on the lower mold 8 by the same molding apparatus as in the first embodiment, and both the lower mold 8 and the first optical element 9 are heated to 506 ° C. Upper die 7 is 45
Heat to 6 ° C. The second optical element 10 is heated to 456 ° C. in another place in the molding apparatus, and the transport robot 11 transports the second optical element 10 onto the first optical element 9 and places it. Then, the upper mold 7 is lowered, and the first optical element 9 and the second optical element 10 are pressure-bonded. Immediately after the joining, cooling is performed to prevent unnecessary temperature rise of the second optical element 10.

The synthetic optical element 12 is formed by the above-described steps. The synthetic optical element 12 is free from cracks and cracks, and good quality is obtained as a diffractive optical element.

Table 2 shows the results of the joining performed by changing the temperature conditions by the above method.

Table 2 First material Lower mold temperature Second material Upper mold temperature Joining result 1 506 ° C 506 100 100 First material cracked 2 506 506 206 206 OK 3 506 506 456 456 OK 4 506 506 466 466 Second material Cracking 5 466 466 100 100 First material cracked 6 466 466 166 166 OK 7 466 466 456 456 OK 8 466 466 466 466 Second material cracked 9 456 456 456 456 Insufficient deformation of second material 10 516 516 456 First material deformed

From the results of the molding according to the first and second embodiments, the temperature of the first material of the first optical elements 3 and 9 is set to a value equal to or lower than the transition point and the second temperature of the second optical elements 4 and 10. The final shape of the first optical element 3, 9 without being higher than the transition point of the material by 10 ° C. or more and lowering the temperature of the second material below the transition point and 300 ° C. or more below the temperature of the first material. A good combined optical element can be obtained by pressure-bonding the surface and the surface opposite to the final shape of the second optical elements 4 and 10.

The transition point is a temperature at which a material transitions from an elastic body to a viscous body, and a material below the transition point is not substantially plastically deformed. In addition, when the material rises in temperature and becomes viscous, it enters the abnormal expansion area and thermal expansion starts rapidly,
Since the first and second optical elements are below the transition point, there is no significant difference in the coefficient of thermal expansion. Therefore, when both are brought into contact with each other and pressurized, the second optical element is heated and deformed in a state where only the surface is softened, and is joined to the first optical element. After joining,
Immediately cooling prevents a temperature rise other than the surface of the second optical element. At this time, the joining surface of the first optical element is not deformed, the shape before joining is maintained, and the state in which the difference between the thermal expansion coefficients of the first and second optical elements is small is maintained. The generation of cracks during cooling can be prevented.

Regarding the selection of the materials used for the first and second optical elements, it is a condition on the temperature characteristic that the transition point of the first material is higher than the transition point of the second material. Further, since the non-joining surfaces of the first and second optical elements have the final shape, it is necessary that the shape of the mold that comes into contact with the material at the time of press-fitting matches the final shape. If it is spherical or spherical, it is not so difficult to make the surface of the mold to this.

If the temperature of the first material is higher than the transition point, the shape of the molded first optical element changes, while the temperature of the first material is higher than the transition point of the second material by 10 ° C. or more. If not, it is insufficient to heat the surface of the second optical element. When the temperature of the second material is higher than its transition point, the region becomes abnormally expanded, so that the coefficient of thermal expansion becomes large, cracks occur after joining, and the temperature of the first material is 300 ° C. lower than the first material temperature.
If the temperature is lowered by not less than ° C., when the first optical element comes into contact with the first optical element, the first optical element is broken by rapid cooling.

When holding for a long time after the pressure bonding, the temperature of not only the surface of the second optical element but also the entire second optical element rises, and the whole becomes an abnormal expansion area, and a large stress is generated. There is a great risk that the two optical elements will break.

In the present invention, when the second optical element is deformed and joined to the first optical element, a smaller amount of deformation is advantageous in that the temperature rise of the entire second optical element can be prevented. It is. In a diffraction grating or the like, since the depth of the fine pattern portion on the surface is extremely small at several tens μm or less,
The molding method in the present invention is effective.

FIG. 5 is a front view of a photographic camera equipped with a synthetic optical element, and FIG. 6 is a sectional view. Camera body 2
At 0, a photographing optical system 21 and a finder optical system 22 are arranged, and the combining optical element is arranged at an arbitrary position in the photographing optical system 21 and the finder optical system 22. In this manner, erroneous aberrations such as chromatic aberration of the optical system of the photographic camera 20 can be satisfactorily corrected to improve performance.

The present invention can be applied not only to a photographic camera but also to an optical system of various optical devices such as a video camera, binoculars, a projector mirror, a microscope, and a copying machine to improve the optical characteristics.

[0032]

As described above, in the synthetic optical element according to the present invention, the material temperature of the first optical element is set to be lower than the transition point and higher than the transition point of the material of the second optical element by 10 ° C. or more. The material temperature of the second optical element is below the transition point and the first
By lowering the final temperature of the first optical element and the opposite face of the second optical element by pressure without lowering the material temperature by 300 ° C. or more, no cracking or cracking occurs It can be manufactured efficiently.

Further, in the method for molding a synthetic optical element, the material temperature of the first optical element is set to be lower than its transition point and higher than the transition point of the second optical element, and the second optical element is pressurized. By setting the material temperature near the junction with the first optical element at or above its transition point, and setting it so as not to exceed the transition point in other parts, a high-precision synthetic optical element free from cracks and cracks can be obtained. can get.

Further, in the method of molding a synthetic optical element according to the present invention, the material temperature of the first optical element is set to be lower than the transition point and higher by 10 ° C. or more than the transition point of the material of the second optical element.
The reverse of the final shape surface of the first optical element and the final shape of the second optical element, without lowering the material temperature of the second optical element below the transition point and not lower than the first material temperature by 300 ° C. or more. By joining the surfaces under pressure, a synthetic optical element free from cracks and cracks can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment before molding.

FIG. 2 is a cross-sectional view after molding.

FIG. 3 is a sectional view of a second embodiment before molding.

FIG. 4 is a cross-sectional view after molding.

FIG. 5 is a front view of a camera equipped with a synthetic optical element.

FIG. 6 is a side view.

[Explanation of symbols]

 1, 7 Upper mold 2, 8 Lower mold 3, 9 First optical element 4, 10 Second optical element 5, 11 Transfer robot 6, 12 Synthetic optical element 20 Camera body 21 Photographing optical system 22 Viewfinder optical system

Continued on the front page (51) Int.Cl. ⁶ Identification code FI // B29L 11:00

Claims (8)

[Claims] 1. A first and a second made of two different materials.
A composite optical element formed by joining and molding the optical elements of
The material temperature of the first optical element is kept at or below its transition point and at least 10 ° C. higher than the transition point of the material of the second optical element, and the material temperature of the second optical element is kept at or below its transition point. And the second optical element having the non-bonding surface formed in the final shape is pressure-bonded to the first optical element formed in the final shape while holding the temperature without lowering the temperature of the first material by 300 ° C. or more. A synthetic optical element, characterized in that: 2. The method according to claim 1, wherein the first and second optical elements having different materials have a material temperature of the first optical element equal to or lower than its transition point and higher than a transition point of the second optical element. In a method of forming a composite optical element by pressure-bonding a first optical element and a second optical element, a material temperature of the second optical element at the time of pressurization is increased in the vicinity of a joint with the first optical element. A molding method of a synthetic optical element, wherein the transition point is set to be equal to or higher than the transition point and not to exceed the transition point in other portions. 3. The method according to claim 2, wherein the material of the first and second optical elements is glass. 4. The method according to claim 2, wherein a fine pattern is formed on the first optical element to form a diffraction grating. 5. A molding method for manufacturing a synthetic optical element by joining first and second optical elements made of two kinds of materials, wherein a material temperature of the first optical element is set to a value equal to or lower than its transition point. In addition, the temperature of the material of the second optical element is maintained at 10 ° C. or more higher than the transition point of the material, and the material temperature of the second optical element is equal to or less than the transition point of the material and lower than the temperature of the first material by 300 ° C. or more. The first shape held in the final shape
Forming a composite optical element by pressure-bonding the optical element and the second optical element having a non-bonded surface formed into a final shape. 6. The molding method for a synthetic optical element according to claim 5, wherein a temperature of a material of the second optical element is prevented from rising by cooling a mold during the pressure joining. 7. A composite optical element formed by the method according to claim 2. Description: 8. An optical system using the synthetic optical element according to claim 1.