JPS63210912A - Compound body of optical element - Google Patents

Abstract

PURPOSE:To stabilize characteristics of a compound body of optical elements by forming a constricted part at a position for fixing an optical element to a substrate supporting the optical element, or close to the said position, reluxing thus the stress due to the difference of thermal expansion generated between the optical element and the substrate or that generated by the contraction of an adhesive used for adhering the optical element to the substrate. CONSTITUTION:Cut grooves 15, 15 having each specified depth of cut are formed respectively from confronting both sides of an LiNbO3 element 3 at a position between a fixing position 3a of the element and a light transmitting position of the main body 3b of the element. Thus, a constricted part is formed at almost the middle part of 3b as a bonded part of narrow width forming an H-shaped foot of the element. Thus, a structure for adhering the element firmly to a CaTiO3 substrate 10 is obtd. by giving a large bonding area to the fixing position 3a of the LiNbO3 element 3. By this constitution, the output of the compound optical element is discharged stably without being influenced by the change of environmental temp. and contraction of the adhesive.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical element composite, and in particular to a method for fixing at least one optical element, such as an electro-optical element, a magneto-optical element, or an optical component such as a lens, to a predetermined mounting substrate. This invention relates to an optical element composite formed by supporting the present invention.

(Background Art) Conventionally, optical components such as electro-optic elements, magneto-optical elements, lenses, etc., are generally fixed directly to a predetermined mounting board using synthetic resin adhesives, screws, etc. and is applied to the intended use. However, in such a conventional mounting or supporting structure for optical components, due to the difference in thermal expansion coefficient between the optical component and the substrate, the difference in thermal expansion between the optical component and the substrate changes as the environmental temperature changes. This has the inherent problem that stress is applied to optical components, causing displacement and changes in refractive index, or, in the case of electro-optical elements and magneto-optical elements, causing significant changes in their optical properties.

Furthermore, when an adhesive is used, the stress generated by the contraction of the adhesive during bonding can sometimes cause changes in the characteristics of such optical components.

For example, an optical sensor as shown in FIG. 1 can be cited as an example of a composite body in which such an optical component (optical element) is fixed and supported on a predetermined substrate. There, 1 is a light source, 2 is an optical fiber, 3 is an electro-optic crystal, 4a is a polarizer, 4b is an analyzer, 5 is a λ/4 plate,
6 is a rod lens, 7 is a light receiver, and 8 is a light-transmitting electrode provided on the opposite surface of the electro-optic crystal 3. Among these optical parts, at least the electro-optic crystal 3 is made of synthetic resin (adhesive ) 9 to directly adhere to and hold a predetermined mounting board 10.

By the way, as is well known, the operating principle of an optical sensor is to utilize the electro-optic effect or magneto-optic effect. The effect refers to a phenomenon in which the optical properties of crystals change when a magnetic field is applied to the crystals.

And lithium niobate (L I N b O
*) Alternatively, in an optical sensor using a Pockels element such as a Bi1□Si○2° single crystal as the electro-optic crystal 3 in FIG. 1, the light emitted from the light source 1 passes through the polarizer 4a. The light then becomes linearly polarized light, and further passes through the electro-optic crystal 3 to become elliptically polarized light. Further, this elliptically polarized light passes through the λ/4 plate 5 and the analyzer 4b, and the amount of light is changed according to its ellipticity. This amount of light corresponds to the voltage applied to the electrode 8 provided on the electro-optic crystal 3, and by measuring this amount of light, the voltage to be measured can be measured.
In a sensor with such a structure, the electro-optic crystal 3 bonded and held on the mounting substrate 10 may be damaged due to changes in environmental temperature.
There was a problem in that the characteristics of the motor were changed, resulting in a large change in output.

In addition to the electro-optic crystal element shown above, there are other optical elements such as magneto-optic crystal elements, prism lenses, and reflectors. When fixing or adhering an optical element to a substrate made of other materials, if there is a difference in the coefficient of thermal expansion between the two, stress will be applied to the optical element due to environmental temperature changes or shrinkage of the adhesive when it hardens. The characteristics change or the optical element deforms, causing a problem in which the direction of light propagation changes.In extreme cases, repeated environmental temperature changes cause the bonded part to fatigue, and eventually This causes a phenomenon that leads to destruction.

(Problem to be Solved) The present invention has been made against the background of the above circumstances, and its purpose is to prevent damage caused by changes in environmental temperature or An optical element composite that can effectively prevent changes in optical properties due to stress between the substrate and optical components caused by shrinkage of the adhesive during resin bonding. Another object of the present invention is to provide an optical element composite structure such as an optical sensor that can stably output output without being affected by changes in environmental temperature or adhesive shrinkage. It's about doing.

(Solution Means) In other words, in order to achieve the above object, the present invention provides a composite body in which at least one optical element is fixed to and supported by a predetermined substrate, in which at least one of the optical elements and the substrate are bonded to each other. An optical element composite, characterized in that a constriction is formed in either one of the fixed parts or the vicinity thereof, and the presence of the constriction alleviates stress acting on the optical element. The body is its gist.

In addition, in one embodiment according to the present invention,
Providing a convex portion or a convex strip so as to be located approximately in the center of a surface of the optical element that is fixed to the substrate, and fixing the tip of the convex portion or convex strip to the substrate. Accordingly, it is possible to make the convex part or the convex line forming part the constricted part, and on the contrary, with respect to the part of the substrate fixed to the optical element,
It is also possible to similarly provide such convex portions or convex stripes, thereby reducing the area of the fixed portion between the optical element and the substrate and reducing the amount of stress generated. This makes it possible to eliminate or suppress the influence of stress on the optical element.

Further, in the present invention, cut grooves are provided from opposite sides of the optical element in the vicinity of the fixing portion of the optical element to the substrate, and the fixing portion is attached to the substrate approximately at the center thereof. It is also possible to form the constricted portion by connecting it to the optical element main body, and furthermore, by providing one cut groove from one side of the optical element, the optical element can be connected to the main body of the optical element. It is also possible that the fixing portion is connected to the optical element main body at the other side portion of the optical element to form the constricted portion.

Further, on the substrate side, a fixing portion of the substrate to the optical element is formed to protrude from the substrate body, and a cut groove is provided from at least one side of the protruding portion to connect to the substrate body. The constricted portion can also be formed by constricting the portion.

If a predetermined constriction is formed by providing a cut groove in the vicinity of the fixed part of the optical element or the substrate, there is no need to reduce the area of the fixed part of the optical element or the substrate. Therefore, the holding of the optical element does not become unstable, and the stress between the substrate and the optical element can be effectively relaxed at the constricted portion.

(Specific description of the structure) In the present invention, the optical element fixed and supported on a predetermined substrate is an optical element having the electro-optic effect or magneto-optic effect, that is, an electro-optic crystal element or a magneto-optic crystal. In addition to the elements, there are polarizing optical elements such as TiO2 and calcite; rod lens elements; prism lenses; reflectors; and the polarizer shown in Figure 1 (
4a), analyzer (4b), λ/4 plate (5), rod lens (6), etc. are also optical elements, and when these optical elements are fixed to a predetermined substrate, they are particularly sensitive to stress. The present invention can be suitably applied to optical elements to solve problems caused by differences in thermal expansion between the optical element and the substrate.

The electro-optic crystal element used as the optical crystal of the optical sensor includes, for example, L 1Nb03 (lithium niobate), LiTaOz (lithium quintalate), B i+zs i 02°, Bi, □G
Examples of magneto-optic crystal elements include YIG, lead glass, and Zn5e.

The present invention is advantageously applied to fixing and supporting such optical crystals, especially electro-optic crystal elements.

Further, as the substrate to which the optical element is fixed and supported, materials made of various known materials may be appropriately selected and used, such as ceramic substrates, metal substrates, and the like.

The present invention is applied between at least one of the at least one optical element fixed and supported by such a substrate and the substrate. In other words, in order to alleviate the stress caused between the optical element and the substrate, a predetermined confinement is applied to the fixed portion or the vicinity thereof on either side of the optical element and the substrate. A section is formed, and this constriction allows
The influence of stress on the optical element is effectively eliminated or suppressed.

In addition, there are various structures of the constricted portion provided at the fixing site of the optical element or the substrate or the vicinity thereof according to the present invention, as shown in the embodiments described below. It is understood that various structures can be devised based on the knowledge of those skilled in the art without departing from the spirit of the invention, and all such structures fall within the scope of the present invention. Should.

In addition, in order to fix the optical element and the substrate in the presence of such a constriction, an adhesive method using an appropriate resin adhesive is generally adopted, but other methods such as screw fixing and Even if they are fixed integrally using a method such as welding, there is no problem.

(Examples) Below, some examples of the present invention will be shown to clarify the present invention more specifically, but the present invention is not limited in any way by the description of such examples. It goes without saying that this is not something you should accept.

In addition to the following examples and the above-mentioned specific description, the present invention includes various changes, modifications, and changes based on the knowledge of those skilled in the art, as long as they do not depart from the spirit of the present invention. It should be understood that improvements and the like may be made.

Example 1 First, as an electro-optic crystal (3) which is an optical element, an electro-optic crystal (3) whose Z axis coincides with the optical path direction and is parallel to the optical path is prepared.
as X 5 + electrode (8) provided on the n side, 2ml
x 4 +n x 5 Dragon-sized L i N b O
y single crystal and as a substrate, CaTiO:
A polycrystalline material was used. Note that this L i N b Tl
:) When the thermal expansion coefficient of x single crystal was measured, it was 38
X 10-'/"C (Z-axis direction), and 167x10-'/"C in the direction perpendicular thereto. Together with these parts, a λ/4 plate (5) formed with a rod lens (6), a polarizer (4) that also serves as an analyzer, and a mirror (12) made of a dielectric multilayer film is arranged in the arrangement shown in Figure 2. In this step, epoxy resin (9) was applied to the Ca Ti Ox substrate (10).
) to create the desired reflective optical sensor. Note that this sensor is different from the transmission type shown in Figure 1, and has a reflection type configuration for the purpose of miniaturization, so a splitter (1) is installed between the light source (1) and the optical sensor.
3) is provided.

Furthermore, in order to improve the sensor measurement accuracy, a circuit was added to the detector to divide the output of the light receiver (7) into an alternating current component and a direct current component, and to electrically divide the alternating current component by the direct current component.

(-, then add 50■ to the optical sensor configured in this way,
Apply an AC signal of 60H2 and place it in a thermostatic oven for 120H.
When the temperature change of the output signal was investigated between .degree. C. and +80.degree. C., it was found that there was a 4% output fluctuation.

On the other hand, as shown in FIG. 3(a), with respect to the fixed part (lower part) of the L i N b O3 single crystal (3), a A protruding strip (14) of unit: 1 cm (the same applies hereinafter) is provided, and the adhesive surface at the tip of the protruding strip (14) is 111 x 2 x 1, and as shown in Fig. 3(b), a resin adhesive is applied. (9)
When an optical sensor was assembled in the same manner as above by adhering it to the CaTiO:1 substrate (10) using The output fluctuation was 0.7%, and it was recognized that the output fluctuation range was significantly improved.

In addition, the above LiNb0:+ element (3) is shown in FIG.
), in the part between the fixed part (3a) and the element body part (3b), which is the light-transmitting part,
Cut grooves (15, 15) of a predetermined depth are provided from both sides facing each other under the dimensions shown in the figure, and the substantially central part is made into a constricted part with a narrow connection part, and is formed into an H-shaped shape. As shown in FIG. 4(b), the fixing area of the fixing part (3a) of the L+NbC1+ element (3) is increased, and the CaTiOz substrate (1
When an optical sensor was assembled in the same manner as above as a structure capable of adhering to 0) and a similar test was conducted, the output fluctuation was 0.5%.

Sarani, LiNbC) + element (3), Fig. 5 (
As shown in a), with dimensions as shown in the figure, a protruding strip (16) is left at approximately the center of the substrate fixing surface at the bottom, and grooves (17, 17) are formed on the left and right sides of the protruding strip (16), and As shown in FIG. 5(b), the convex strip (1
6) at the tip of the CaT i O:l substrate (1
When an optical sensor having a structure fixed at 0) was assembled in the same manner as above and a similar test was conducted, the output fluctuation was 0.8%.

Example 2 As an electro-optic crystal (3) which is an optical element, a 4 mu crystal whose Z axis coincides with the optical path direction and is parallel to the optical path is used.
2111 x 4 dragon x with electrodes (8) on the x 5 m plane
5 mm size LiNb0. A single crystal was used, and CaTi0. Polycrystalline material was used.

Furthermore, when we measured the thermal expansion coefficient of this LiNbO single crystal, it was 38 x 10-'/'c (Z-axis direction), and in the direction perpendicular to it, it was 167 x 10-
/”c. Along with these parts, the Rondo lens (
6) A λ/4 plate (5) on which a polarizer (4) which also serves as an analyzer and a mirror (12) made of a dielectric multilayer film are formed is placed on a CaTi0:l substrate (1
0) with epoxy resin (9) to produce the intended reflective optical sensor.

Note that this sensor is different from the transmission type shown in Figure 1, and has a reflection type configuration for the purpose of miniaturization, so a splitter ( 13
) is provided.

Furthermore, in order to improve the sensor measurement accuracy, a circuit was added to the detector to divide the output of the light receiver (7) into an alternating current component and a direct current component, and to electrically divide the alternating current component by the direct current component.

Then, to the optical sensor configured in this way, 5OV, 6V
Apply a 0Hz AC signal and place it in a thermostatic oven at -20℃.
When we investigated the temperature change of the output signal between ~ +80℃, we found that
It was observed that there was a 4% output fluctuation.

On the other hand, L i N b O! in FIG. Element (3)
With respect to the fixed substrate (10), as shown in FIG. 6(a), under the dimensions shown in the figure, a protruding strip (18) is left at approximately the center of the element fixing surface (fixed part), and a protruding strip (18) is left on the left and right sides of the protruding strip (18). A concave groove (19, 19) is formed, and a convex line (18
) at the tip of LiN via resin adhesive (9).
b0. The element (3) was fixed as shown in FIG. 6(b) to assemble the desired optical sensor, and the above Example 1 was assembled.
When a similar test was conducted, the output fluctuation was 0.9
%, indicating a significant improvement.

In addition, as shown in FIG. 7(a), the left and right grooves (1) forming the protruding stripes (18) of the CaT i03 substrate (10) are
9, 19) are made narrow as shown in the figure, and the outer edges (20, 20) of the grooves (19, 19) support the Li, NbO3 element (3). (
10), assemble the optical sensor in the same manner as above,
When a similar test was conducted, the output fluctuation was 0.7%.
It became.

Example 3 The LiNb0. As elements (3) made of single crystal, elements having constricted portions of various shapes as shown in FIGS. It was fixed and held through agent (9) to produce the desired optical sensor.

In other words, the optical element (3) shown in FIGS. 8 and 10 is one in which the optical element (3) itself has been processed, and the
), a cut groove (21) is formed from one side of the element in the vicinity of the fixed part (3a) of the element (3) and the element main body part (3b), In this case, as shown in FIG. 8(b), the substrate ( 1
0).

Further, in the structure shown in FIG. 10(a), a convex portion (22) is provided at the center of the fixing surface (bottom surface) of the element (3), and at the tip of this convex portion (22), Figure 10 (b
), the substrate (1) is attached via the resin adhesive (9).
0) is structured to be fixed and held.

On the other hand, the structure shown in FIG. 9 and FIG.
0), and in Fig. 9,
Predetermined cut grooves (23, 23) are formed from both sides of the fixed portion protruding from the substrate (10), and the central portion thereof serves as a connecting portion, thereby forming a constricted portion. The element (3) is fixed to the upper surface of the large fixed area via the resin adhesive (9). Furthermore, in the case shown in FIG. 11, as is clear from FIG. 11 (a), a convex portion (24) is formed on the upper surface of the substrate (10), and As shown in FIG. 11(b), a predetermined element (3) is fixed via a resin adhesive (9).

In addition, FIG. 12 shows a magneto-optical crystal (YI) as an optical element.
G) Although the arrangement according to another example of the optical sensor using 25 is shown, the present invention can also be applied to the magneto-optic crystal 25 of such an optical sensor, for example, the 13th In the structure shown in FIGS. 14 and 14, it can be fixed to the substrate 10.

(Effects of the Invention) As is clear from the above description, the present invention provides a desired constriction in the fixed portion of the optical element and the substrate that supports it or in the vicinity thereof, so that the optical element and the substrate supporting the optical element can be bonded together. It is designed to effectively alleviate stress caused by the difference in thermal expansion between the substrate and the shrinkage of the adhesive during resin bonding. The present invention can advantageously provide an optical element composite whose properties are stable against shrinkage, and this is where the great industrial significance of the present invention lies.

[Brief explanation of the drawing]

1 and 2 are layout configuration diagrams showing an example of an optical sensor made of an optical element composite, respectively, and FIG. 3 (a
) and (b), Figure 4 (a) and (b), Figure 5 (a)
and (b), Figures 8 (a) and (b), and Figure 10 (
6(a) and (b) are respectively a perspective view of an optical element showing an example in which a constricted portion according to the present invention is provided on the optical element side and an explanatory view of the state in which it is attached to a substrate;
), FIGS. 7(a) and (b), and FIGS. 11(a) and (b) are perspective explanatory views showing an example in which the constricted portion according to the present invention is provided on the substrate side, and the relationship between the constricted portion and the optical element, respectively. FIG. 9 is an explanatory diagram of an attached state to an optical element showing another example in which a constricted portion according to the present invention is provided on the substrate side. FIG. 12 is a layout configuration diagram of an example of an optical sensor using a magneto-optic crystal, FIG. 13 is a perspective explanatory view showing an example in which a constriction according to the present invention is provided in a magneto-optic crystal, and FIG. FIG. 3 is an explanatory diagram of a state in which such a magneto-optic crystal is fixed to a substrate. 1: Light a 2: Optical fiber 3: Electro-optic crystal 4a: Polarizer 4b: Analyzer 5: λ/4 hand 6: Rosodo lens 7: Light receiver
8: Electrode 9: Adhesive 10: Substrate 12; Mirror 13: Brancher 14.16. ts: Convex 15.21, 23: Cut groove 17.19: Concave groove 20: Edge 22.24 = Convex 25: Magneto-optic crystal

Claims (7)

[Claims] (1) fixing at least one optical element to a predetermined substrate;
In the composite body that supports the optical element, a constriction is formed at a fixed portion of at least one of the optical elements and either one of the substrates or a portion near the fixed portion, and the existence of the constriction allows the optical An optical element composite body characterized in that the stress acting on the element is relaxed. (2) A convex portion or a convex strip is provided so as to be located approximately in the center of the surface of the optical element that is fixed to the substrate, and a tip of the convex portion or convex strip is attached to the substrate. Claim 1, characterized in that the convex portion or the convex strip forming portion is made into the constricted portion by fixing it.
Optical element composite as described in . (3) Cut grooves are provided from opposing sides of the optical element in the vicinity of the fixing portion of the optical element to the substrate, and the fixing portion is connected to the optical element main body at approximately the center thereof. 2. The optical element composite according to claim 1, wherein the constricted portion is formed by making the constricted portion. (4) A cut groove is provided from one side of the optical element in the vicinity of the fixing part of the optical element to the substrate, and the fixing part is fixed to the optical element at the other side part of the optical element. 2. The optical element composite according to claim 1, wherein the constricted portion is formed by connecting it to the element body. (5) A convex portion or a convex strip is provided so as to be located approximately at the center of the fixing portion of the substrate to the optical element, and the tip of the convex portion or convex strip is fixed to the optical element. 2. The optical element composite according to claim 1, wherein the convex portion or the convex line forming portion is formed as the constricted portion by tightening the convex portion. (6) The optical element composite according to claim 5, wherein the convex portion or the protruding strip is formed by a concave portion or a groove portion provided at a portion of the substrate that is fixed to the optical element. (7) A portion of the substrate fixed to the optical element is formed to protrude from the substrate main body, and a cut groove is provided from at least one side of the protruding portion to narrow the connection portion to the substrate main body. 2. The optical element composite according to claim 1, wherein said constricted portion is formed by said constricted portion.