KR102737599B1 - Method for manufacturing acousto-optic tunable filter - Google Patents

Abstract

The present invention relates to a method for manufacturing an acousto-optic tunable filter, and more particularly, to provide a method for manufacturing an acousto-optic tunable filter for manufacturing an AOTF (acousto-optic tunable filter) having excellent acousto-optic characteristics in a long-wavelength infrared band of 8 to 12 ㎛.

Description

{METHOD FOR MANUFACTURING ACOUSTO-OPTIC TUNABLE FILTER}

The present invention relates to a method for manufacturing an acousto-optic tunable filter, and more particularly, to a method for manufacturing an acousto-optic tunable filter for manufacturing an AOTF (acousto-optic tunable filter) having excellent acousto-optic characteristics in a long-wavelength infrared band of 8 to 12 ㎛.

Hyperspectral Imaging (HSI) is a technology that adds spectral technology to spatial information. It refers to a technology that organizes two-dimensional image information according to the spectral band of electromagnetic waves into the form of a hyperspectral cube to derive the state, composition, feature, and transform of a target object. Since a color camera or the human eye recognizes the color or state of an object by obtaining red, green, and blue spectral information respectively, it can be called spectral imaging, but hyperspectral imaging usually refers to a case where there is a larger number of spectral bands than this. Hyperspectral imaging has more than 100 spectral bands, and may be capable of a spectral resolution that can identify the properties of a material.

An acousto-optic tunable filter (AOTF) can be used as an optical tunable filter in a spectral dispersive device for hyperspectral imaging.

Acousto-optic tunable filters use the principle of forming perturbations of a certain frequency in a crystalline material through the vibration of a piezoelectric transducer, and allowing only certain wavelengths to pass through the interaction of the perturbations and photons of an incident beam. The operating wavelength range of acousto-optic tunable filters is very wide, from ultraviolet (UV) to infrared (IR) region, and the wavelength tuning speed is very fast, at tens of μsec, so they are used in many applications.

An acousto-optic tunable filter includes a bonded structure in which a single crystal through which light passes and a piezoelectric transducer that vibrates the single crystal are bonded, and the state of the bonded structure can affect the quality of a hyperspectral image ultimately produced and the lifespan of the acousto-optic tunable filter.

To acquire high-quality hyperspectral images, a technology for manufacturing acousto-optic tunable filters that can minimize device damage and performance degradation even after long-term use is required.

The present invention relates to a method for manufacturing an acousto-optic tunable filter, and more particularly, to provide a method for manufacturing an acousto-optic tunable filter for manufacturing an AOTF (acousto-optic tunable filter) having excellent acousto-optic characteristics in a long-wavelength infrared band of 8 to 12 ㎛.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by a person having ordinary skill in the technical field to which the present invention belongs from the description below.

The method for manufacturing an acousto-optic variable filter of the present invention is:

Single crystal preparation step for preparing a single crystal;

A single crystal fixing step of mounting and fixing the single crystal on a fixing jig;

A first bonding step of applying an acidic adhesive to the single crystal to bond the front layer to the single crystal; and

It may include a second bonding step of applying an adhesive to the front layer to bond the piezoelectric transducer to the front layer.

In the single crystal preparation step of the method for manufacturing an acousto-optic tunable filter of the present invention, the material of the single crystal may be Hg ₂ Br ₂ .

In the single crystal preparation step of the method for manufacturing an acousto-optic tunable filter of the present invention, when a virtual plane is referred to as a reference plane, the single crystal may include an incident plane perpendicular to the reference plane, a vibration plane perpendicular to the reference plane and forming an acute angle with the incident plane, an emission plane perpendicular to the reference plane and forming an obtuse angle with the vibration plane, and a fixed plane perpendicular to the reference plane and forming an obtuse angle with each of the incident plane and the emission plane.

In the single crystal fixing step of the method for manufacturing an acousto-optic variable filter of the present invention, the fixing jig includes a first fixing surface to which the incident surface is closely fixed and fixed, and a second fixing surface to which the fixing surface is closely fixed and fixed, and an angle between the first fixing surface and the second fixing surface may be the same as the angle between the incident surface and the fixing surface.

In the single crystal fixing step of the method for manufacturing an acousto-optic variable filter of the present invention, a protective groove may be formed in the fixing jig between the first fixing surface and the second fixing surface into which an edge of the single crystal formed by meeting the incident surface and the fixing surface is inserted.

In the single crystal fixing step of the method for manufacturing an acousto-optic variable filter of the present invention, the material of the fixing jig may be made of Teflon.

In the single crystal fixing step of the method for manufacturing an acousto-optic variable filter of the present invention, the fixing jig may include a pressure surface parallel to the vibration surface, and the pressure surface may be connected to the first fixing surface.

In the first bonding step or the second bonding step of the method for manufacturing an acousto-optic variable filter of the present invention, the vibrating surface may be pressed by a pressurizing jig.

In the first bonding step of the method for manufacturing an acousto-optic variable filter of the present invention, the acidic adhesive may be applied between the front layer and the vibrating surface, and the front layer may be fixed to the single crystal by the acidic adhesive.

In the first bonding step of the method for manufacturing an acousto-optic variable filter of the present invention, the acidic adhesive may have a pH of 5 or lower.

In the second bonding step of the method for manufacturing an acousto-optic variable filter of the present invention, a first ground electrode may be formed on one side of the piezoelectric transducer, a signal electrode may be formed on a first region of the other side of the piezoelectric transducer, a second ground electrode may be formed on a second region of the other side of the piezoelectric transducer, a signal line may be connected to the signal electrode, a ground line may be connected to the second ground electrode, the first ground electrode and the second ground electrode may be electrically connected, and an area of the first region may be formed to be wider than an area of the second region.

In the second bonding step of the method for manufacturing an acousto-optic variable filter of the present invention, an adhesive may be applied between the first ground electrode and the front layer so that the piezoelectric transducer is fixed to the front layer.

The method for manufacturing an acousto-optic variable filter of the present invention may further include, after the second bonding step, a sound-absorbing layer forming step of laminating a sound-absorbing material on the vibrating surface to cover the piezoelectric transducer.

The method for manufacturing an acousto-optic tunable filter of the present invention can manufacture an AOTF (acousto-optic tunable filter) having excellent acousto-optic characteristics in a long-wavelength infrared band of 8 to 12 ㎛.

The method for manufacturing an acousto-optic tunable filter of the present invention may enable the manufacture of an acousto-optic tunable filter having a single crystal made of mercury bromide (Hg ₂ Br ₂ ) having transparent birefringence characteristics in a long-wavelength infrared band of 8 to 12 ㎛ and an excellent acousto-optic performance index.

The method for manufacturing _an acousto-optic tunable filter of the present invention may be capable of manufacturing an acousto-optic tunable filter that minimizes device damage and performance deterioration even after long-term use based on a single crystal prepared from mercury bromide (Hg ₂ Br 2 ) material.

Figure 1 is a block diagram showing a method for manufacturing an acousto-optic variable filter of the present invention.
Figure 2 is a front view showing a single crystal.
Figure 3 is a perspective view showing a fixed jig.
Figure 4 is a front view showing a single crystal mounted on a fixed jig.
Figure 5a is a photograph showing a state in which the acidic adhesive of the present invention is applied to a single crystal.
Figures 5b to 5d are photographs showing a state in which an alkaline adhesive is applied to a single crystal.
Figure 6 is a cross-sectional view showing a piezoelectric transducer.
Figure 7 is a cross-sectional view showing a piezoelectric transducer coupled to a single crystal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. In this process, the sizes and shapes of components illustrated in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms specifically defined in consideration of the configuration and operation of the present invention may vary depending on the intention or custom of the user or operator. The definitions of these terms should be made based on the contents throughout this specification.

In the description of the present invention, it should be noted that the direction or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "one side", "the other side", etc., is based on the direction or positional relationship shown in the drawings, or the direction or positional relationship in which the product of the present invention is normally placed when used, and is only for the purpose of explaining and briefly explaining the present invention, and does not suggest or imply that the indicated device or element must have a specific direction and be configured or operated in a specific direction, and therefore should not be understood as limiting the present invention.

FIG. 1 is a block diagram showing a method for manufacturing an acousto-optic variable filter of the present invention. FIG. 2 is a front view showing a single crystal (100). FIG. 3 is a perspective view showing a fixing jig (200). FIG. 4 is a front view showing a state where a single crystal (100) is mounted on a fixing jig (200). FIG. 5a is a photograph showing a state where an acidic adhesive of the present invention is applied to a single crystal (100). FIGS. 5b to 5d are photographs showing a state where an alkaline adhesive is applied to a single crystal (100). FIG. 6 is a cross-sectional view showing a piezoelectric transducer (300). FIG. 7 is a cross-sectional view showing a state where a piezoelectric transducer (300) is coupled to a single crystal (100).

Hereinafter, with reference to FIGS. 1 to 7, a method for manufacturing an acousto-optic variable filter of the present invention will be described in detail.

The method for manufacturing an acousto-optic tunable filter of the present invention may be for manufacturing an acousto-optic tunable filter (AOTF) that controls the spectral degree of light by modulating the refractive index of a single crystal (100) by applying vibration (sound waves) to a single crystal (100) through which light is transmitted.

As shown in Fig. 1, the method for manufacturing an acousto-optic variable filter of the present invention,

Single crystal preparation step (S10) for preparing a single crystal (100);

A single crystal fixing step (S20) of mounting and fixing the single crystal (100) on a fixing jig (200);

A first bonding step (S30) of applying an acidic adhesive to the single crystal (100) to bond the front layer (400) to the single crystal (100); and

It may include a second bonding step (S40) of applying an adhesive to the front layer (400) to bond the piezoelectric transducer (300) to the front layer (400).

In the above single crystal preparation step (S10), the material of the single crystal (100) may be Hg ₂ Br ₂ . The present invention is for manufacturing an AOTF (acousto-optic tunable filter) having excellent acousto-optic characteristics in a long-wavelength infrared band of 8 to 12 ㎛, and a single crystal (100) may be prepared using a Hg ₂ Br ₂ material having high transparency in the corresponding wavelength band. The single crystal (100) may be manufactured using a PVT (physical vapor transport) method.

As illustrated in FIG. 2, in the single crystal preparation step (S10), when a virtual plane is referred to as a reference plane, the single crystal (100) may include an incident plane (110) that is perpendicular to the reference plane, a vibration plane (120) that is perpendicular to the reference plane and forms an acute angle with the incident plane (110), an emission plane (130) that is perpendicular to the reference plane and forms an obtuse angle with the vibration plane (120), and a fixed plane (140) that is perpendicular to the reference plane and forms an obtuse angle with each of the incident plane (110) and the emission plane (130). In FIG. 2, the z-axis direction may be a direction perpendicular to the reference plane. That is, the reference plane may be a plane parallel to the xy plane.

For example, a single crystal (100) can be provided in a square prism shape with the incident surface (110), the vibration surface (120), the emission surface (130), and the fixed surface (140) as sides and a plane perpendicular to the z-axis as both ends.

As described above, the incident surface (110), the vibration surface (120), the emission surface (130), and the fixed surface (140) have acute and obtuse angle relationships, so that the planes facing each other may not be parallel. That is, the incident surface (110) and the emission surface (130) are not parallel to each other, and the vibration surface (120) and the fixed surface (140) may also not be parallel to each other.

As illustrated in FIG. 3, in the single crystal fixing step (S20), the fixing jig (200) includes a first fixing surface (210) to which the incident surface (110) is closely fixed and fixed, and a second fixing surface (220) to which the fixing surface (140) is closely fixed and fixed, and the angle between the first fixing surface (210) and the second fixing surface (220) may be the same as the angle between the incident surface (110) and the fixing surface (140). For example, the fixing jig (200) may be prepared by cutting a corner of one of the structures provided in a rectangular parallelepiped shape to form a groove having the first fixing surface (210) and the second fixing surface (220) as inner surfaces. In the single crystal fixing step (S20), the material of the fixing jig (200) may be prepared as Teflon.

In the above single crystal fixing step (S20), a protective groove (230) may be formed in the fixing jig (200) between the first fixing surface (210) and the second fixing surface (220), into which the corner of the single crystal (100), which is formed when the incident surface (110) and the fixing surface (140) meet, is inserted. The protective groove (230) can prevent the corner of the single crystal (100), which is formed when the incident surface (110) and the fixing surface (140) meet, from being damaged during the process of mounting the single crystal (100) on the fixing jig (200). In addition, during the bonding process of the front layer (400) or the piezoelectric transducer (300), the single crystal (100) is pressed while being fixed to the fixing jig (200), and even at this time, the corner can be protected by the protective groove (230). In the method for manufacturing an acousto-optic tunable filter of the present invention, the single crystal (100) is formed relatively softly by being made of a Hg ₂ Br ₂ material, and the single crystal (100) can be prevented from being damaged in the first bonding step (S30) or the second bonding step (S40) by the protective groove (230).

In the above single crystal fixing step (S20), the fixing jig (200) may include a pressure surface (240) parallel to the vibration surface (120), and the pressure surface (240) may be connected to the first fixing surface (210). Specifically, a second fixing surface (220) may be connected to one end of the first fixing surface (210) with a protective groove (230) therebetween, and a pressure surface (240) may be connected to the other end of the first fixing surface (210).

In the first bonding step (S30) or the second bonding step (S40), the vibrating surface (120) may be pressed by a pressurizing jig. The pressurizing jig may pressurize the front layer (400) or the piezoelectric transducer (300) laminated on the vibrating surface (120) to assist bonding. At this time, the pressurizing jig may be prevented from tilting by being in close contact with the pressurizing surface (240). A step or groove may be formed on the pressurizing surface (240) of the pressurizing jig in consideration of the thickness and shape of the front layer (400) or the piezoelectric transducer (300).

In the first bonding step (S30), the acidic adhesive may be applied between the front layer (400) and the vibration surface (120), and the front layer (400) may be fixed to the single crystal (100) by the acidic adhesive. In the first bonding step (S30), the acidic adhesive may have a pH of 5 or lower. Since the single crystal (100) is made of a Hg ₂ Br ₂ material, if an alkaline adhesive is used, the single crystal (100) and the adhesive may react, thereby deteriorating the single crystal (100) or reducing the adhesive strength. Therefore, it may be desirable to apply an acidic adhesive having a pH of 5 or lower between the front layer (400) and the vibration surface (120) to protect the single crystal (100) and maintain the adhesive strength.

The front layer (400) may be laminated between the piezoelectric transducer (300) provided in a plate shape and the single crystal (100). The front layer (400) may be for acoustic matching between the piezoelectric transducer (300) and the single crystal (100). The front layer (400) may be provided with a larger area than the piezoelectric transducer (300). The material of the front layer (400) may be selected without limitation from among synthetic resin, metal, ceramic, composite material, etc., taking into consideration the acoustic impedance of the piezoelectric transducer (300) and the single crystal (100).

FIGS. 5a to 5d are photographs taken after applying adhesives of different pHs to a single crystal (100). FIG. 5a is a photograph of applying an adhesive of pH 4 to 5, FIG. 5b is a photograph of applying an adhesive of pH 7 to PH 8, FIG. 5c is a photograph of applying an adhesive of pH 9 to 10, and FIG. 5b is a photograph of applying an adhesive of pH 11. In FIGS. 5b to 5d, the single crystal (100) was altered by the adhesive, but in FIG. 5a, the single crystal (100) was not altered even after applying the adhesive.

As illustrated in FIG. 6, in the second bonding step (S40), a first ground electrode (310) is formed on one side of the piezoelectric transducer (300), a signal electrode (330) is formed on a first region of the other side of the piezoelectric transducer (300), a second ground electrode (320) is formed on a second region of the other side of the piezoelectric transducer (300), a signal line (331) is connected to the signal electrode (330), a ground line (321) is connected to the second ground electrode (320), the first ground electrode (310) and the second ground electrode (320) are electrically connected, and the area of the first region may be formed to be wider than the area of the second region.

As illustrated in FIG. 7, in the second bonding step (S40), an adhesive may be applied between the first ground electrode (310) and the front layer (400) so that the piezoelectric transducer (300) may be fixed to the front layer (400). The piezoelectric transducer (300) may be formed by stacking a first ground electrode (310) and a signal electrode (330) on each of the two sides of a piezoelectric member (340). At this time, since the first ground electrode (310) must be in complete contact with the front layer (400) as described above, the ground wire (321) cannot be connected to the first ground electrode (310). Therefore, a second ground electrode (320) for connecting the ground wire (321) may be provided on the other side to which the signal electrode (330) is bonded. The signal electrode (330) and the second ground electrode (320) may be spaced apart from each other or an insulating material may be inserted between them so as not to conduct current to each other. Since an excessive area of the second ground electrode (320) may deteriorate the performance of the piezoelectric transducer (300), it may be preferable that the area of the signal electrode (330) be less than 10%.

The ground wire (321) and signal wire (331) may be electrical wires for conducting electricity that include a conductive material.

The first ground electrode (310) and the second ground electrode (320) may be connected by a conductive electrically conductive member (311). The electrically conductive member (311) may electrically connect the first ground electrode (310) and the second ground electrode (320) through a side surface of the piezoelectric member (340) or by penetrating the piezoelectric member (340).

The piezoelectric element (340) may be prepared by cutting an LN wafer made of LiNbO ₃ material.

The method for manufacturing an acousto-optic variable filter of the present invention may further include a sound-absorbing layer forming step of laminating a sound-absorbing material to cover the piezoelectric transducer (300) on the vibrating surface (120) after the second bonding step (S40).

Although the embodiments according to the present invention have been described above, they are merely exemplary, and those with ordinary knowledge in the relevant field will understand that various modifications and equivalent embodiments are possible from this. Accordingly, the true technical protection scope of the present invention should be determined by the following patent claims.

100...single crystal 110...incident surface
120...vibration surface 130...exit surface
140...Fixed surface 200...Fixed jig
210...1st anchorage surface 220...2nd anchorage surface
230...Protective home 240...Pressure surface
300...Piezoelectric transducer 310...First ground electrode
311... Absence of current 320... Second ground electrode
321...Ground wire 330...Signal electrode
331...Signal line 340...Piezoelectric element
400...Front floor

Claims (13)

Single crystal preparation step for preparing a single crystal;
A single crystal fixing step of mounting and fixing the single crystal on a fixing jig;
A first bonding step of applying an acidic adhesive to the single crystal to bond the front layer to the single crystal; and
A second bonding step of applying an adhesive to the front layer to bond the piezoelectric transducer to the front layer,
In the above single crystal preparation step, when the virtual plane is referred to as the reference plane,
The single crystal includes an incident plane perpendicular to the reference plane, a vibration plane perpendicular to the reference plane and forming an acute angle with the incident plane, an exit plane perpendicular to the reference plane and forming an obtuse angle with the vibration plane, and a fixed plane perpendicular to the reference plane and forming an obtuse angle with each of the incident plane and the exit plane.
A method for manufacturing an acousto-optic variable filter, further comprising, after the second bonding step, a sound-absorbing layer forming step of laminating a sound-absorbing material to cover the piezoelectric transducer on the vibrating surface. In the first paragraph,
In the above single crystal preparation step,
A method for manufacturing an acousto-optic tunable filter, wherein the material of the single crystal is Hg ₂ Br ₂ . delete In the first paragraph,
In the above single crystal fixation step,
The above fixed jig is,
A first fixing surface to which the above-mentioned entrance surface is closely fixed,
The above fixed surface includes a second fixing surface to which the fixed surface is closely fixed,
A method for manufacturing an acousto-optic tunable filter, wherein the angle between the first mounting surface and the second mounting surface is the same as the angle between the incident surface and the fixed surface. In paragraph 4,
In the above single crystal fixation step,
A method for manufacturing an acousto-optic variable filter, wherein a protective groove is formed in the above-mentioned fixed jig, into which an edge of the single crystal formed by the meeting of the incident surface and the fixed surface is inserted between the first and second fixed surfaces. In paragraph 4,
In the above single crystal fixation step,
A method for manufacturing an acousto-optic variable filter, wherein the material of the above-mentioned fixed jig is made of Teflon. In paragraph 4,
In the above single crystal fixation step,
The above fixed jig includes a pressure surface parallel to the vibration surface,
A method for manufacturing an acousto-optic variable filter, wherein the above-mentioned pressure surface is connected to the above-mentioned first mounting surface. In Article 7,
In the first bonding step or the second bonding step,
A method for manufacturing an acousto-optic variable filter, wherein the above-mentioned vibrating surface is pressed by a pressurizing jig. In the first paragraph,
In the above first bonding step,
The acid adhesive is applied between the front layer and the vibration surface,
A method for manufacturing an acousto-optic tunable filter, wherein the front layer is fixed to the single crystal by the acid adhesive. In Article 9,
In the above first bonding step,
A method for manufacturing an acousto-optic variable filter, wherein the acidic adhesive has a pH of 5 or less. In the first paragraph,
In the second bonding step,
A first ground electrode is formed on one side of the above piezoelectric transducer,
A signal electrode is formed in the first region of the other side of the piezoelectric transducer,
A second ground electrode is formed in the second region of the other side of the piezoelectric transducer.
A signal line is connected to the above signal electrode,
A ground wire is connected to the above second ground electrode,
The above first ground electrode and the above second ground electrode are electrically connected,
A method for manufacturing an acousto-optic variable filter, wherein the area of the first region is formed to be wider than the area of the second region. In Article 11,
In the second bonding step,
A method for manufacturing an acousto-optic tunable filter, wherein an adhesive is applied between the first ground electrode and the front layer so that the piezoelectric transducer is fixed to the front layer. delete