TWM638335U - All-fiber 3D tomography system - Google Patents

Abstract

An all-fiber three-dimensional tomographic scanning system includes a swept frequency laser, a first optical coupler, a first optical circulator, a first optical collimator, a first convex lens, an electronically controlled attenuator, a second optical circulator, a second A light collimator, a second convex lens, a second light coupler and a balance detector. The all-fiber 3D tomography system includes frequency-sweeping lasers that can use the technology of capturing optical signals to obtain images and adopts an all-fiber line structure, which can quickly perform line or surface scanning on optical scattering media such as biological tissues to obtain high-resolution images. high resolution 3D imagery.

Description

All-fiber 3D tomography system

An optical inspection system, especially an all-fiber three-dimensional tomographic scanning system, which can use the technology of capturing optical signals to obtain images and adopts an all-fiber circuit structure, which can quickly perform line or area scanning on optical scattering media such as biological tissues, etc. to obtain high-resolution 3D images.

In many current industries, it is very important to inspect the surface of tiny structures or to obtain three-dimensional information. In the field of optical interference, interference occurs when the path lengths of the reference and scanning beams coincide with each other. More specifically, the interference generation condition is the coherence length of the light source. Optical interference occurs when the path length difference is less than the source coherence length. Non-transparent specimens can be examined with a Michelson interferometer or a Mirau interferometer. Transparent samples can also be measured by interferometry.

The Michelson interferometer is one of the most commonly used configurations in optical interferometers. By using a beam splitter, the light source is split into two paths. Both beams are reflected back to the beam splitter, which then combines and interferes. The resulting interference pattern, which is not directed back to the light source, is usually directed to some type of photodetector or camera. For different applications of the interferometer, the two optical paths can have different lengths, or can contain optical components or even the material being measured. A light source provides an initial light beam to a beam splitter, which splits the initial light into two beams. One of the two beams is shone onto the sample and the other is shone into the mirror to form a reference path. After the two beams reflect back to the beam splitter, they are combined and directed to a detector, where an interference pattern is generated.

A Mira interferometer is another commonly used optical interferometer configuration. Millau interferometers work on the same principle as Michelson interferometers. The difference between the two is the actual position of the reference arm. The reference arm of the Millau interferometer is located inside the microscope objective assembly. The light source produces an initial beam to a lens L, which refracts the beam to a beam splitter to produce two beams. One beam is shone into the sample and the other beam is reflected back to the half mirror on the lens L. Another optical system can be applied to combine the two beams to generate an interference pattern. For example, if the sample can be transparent, another optical system is configured below the sample. If the sample is opaque, an optical system with mirrors to collect the two beams should be placed above the sample.

Although both Michelson and Millau interferometers are widely used, only one beam is used to probe the sample, and using a reference beam creates interference. Therefore, in both cases at most only half of the light from the light source can reach the sample surface. This greatly limits the ability to detect fine features on the sample surface. Furthermore, the reference path is critical to the system, which leads to the complexity of the Michelson interferometer. Although interference results can be obtained using a Millau interferometer, in non-transparent samples, backscattered light must be used for interference, which further reduces the light intensity irradiated on the sample and easily loses information about the depth and thickness of the sample.

Therefore, how to solve the problems and deficiencies of the above-mentioned prior art is the subject that the related industry is eager to research and develop.

This creation provides an all-fiber three-dimensional tomographic scanning system, especially for high-speed three-dimensional tomographic scanning of the object to be observed. The all-fiber three-dimensional tomographic scanning system includes a frequency-sweeping laser, a first optical coupler, a first optical scanning module, a second Two optical scanning modules, a second optical coupler and a balance detector. Frequency-swept lasers are used to emit laser light of different wavelengths. The first optical coupler is connected to the frequency-sweeping laser with an optical fiber, and the first optical coupler is used to receive the initial incident light emitted by the frequency-sweeping laser, and split it into the first incident light and the second incident light , wherein the number of first incident rays is 40 to 60 times that of the second incident rays. The first optical scanning module is connected to the first optical coupler by an optical fiber to receive the first incident light, wherein the first incident light is sent to the object to be observed to generate the first reflected light. The second optical scanning module is connected to the first optical coupler by an optical fiber to receive the second incident light, wherein the second incident light is sent to a plane mirror to generate the second reflected light. The second optical coupler is connected to the first optical scanning module and the second optical scanning module by optical fibers to combine the first reflected light and the second reflected light respectively, wherein the two output ports of the second optical coupler output the same The first target light and the second target light of the light quantity perform optical interference effect with each other. The balance detector is connected to two output ports of the second optical coupler by optical fibers to receive the first target light and the second target light, and output an optical measurement signal after signal processing.

In an embodiment of the present invention, the first optical scanning module includes a first optical circulator, a first optical collimator, a first convex lens and an electronically controlled attenuator. The first optical circulator is connected to the first optical coupler by an optical fiber to receive the first incident light, wherein the first incident light enters from the first port of the first optical circulator and exits from the second port. The first optical collimator is connected to the second port of the first optical circulator by an optical fiber, and the first optical collimator is used for converting the divergent light of the first incident light into parallel light. The first convex lens is disposed in front of the first light collimator, wherein the first incident light passes through the first light collimator and passes through the first convex lens to the object to be observed, so as to generate the first reflected light. The input port of the electronically controlled attenuator is connected to the third port of the first optical circulator by optical fiber to receive the first reflected light and attenuate it according to an attenuation parameter value.

In an embodiment of the present invention, the second optical scanning module includes a second optical circulator, a second optical collimator, and a second convex lens. The second optical circulator is connected to the first optical coupler by an optical fiber to receive the second incident light, wherein the second incident light enters from the first port of the second optical circulator and exits from the second port. The second optical collimator is connected to the second port of the second optical circulator by an optical fiber, and the second optical collimator is used for converting the divergent light of the second incident light into parallel light. The second convex lens is arranged in front of the second light collimator, wherein the second incident light passes through the second light collimator and passes through the second convex lens to a plane mirror to generate a second reflected light.

In one embodiment of the present invention, the two input ports of the second optical coupler are respectively connected to the output port of the electronically controlled attenuator and the third port of the second optical circulator with optical fibers so as to separate the first reflected light and the second optical circulator respectively. The reflected rays are combined.

In an embodiment of the present invention, the first incident light and the second incident light respectively reach the object to be observed and the plane mirror at the same time.

In one embodiment of the present invention, the first reflected light and the second reflected light reach the second optical coupler at the same time.

In one embodiment of the present invention, the attenuation parameter value of the electronically controlled attenuator is manually or automatically set according to the type of the object to be observed.

To sum up, the all-fiber 3D tomography system disclosed in this creation can bring the following effects: 1. It can quickly perform line or surface scanning on optical scattering media such as biological tissues to obtain high-resolution three-dimensional images; 2. It is easier and more accurate to set up the entire optical tomography system through fiber optic lines; and 3. It has high elastic expansion capability, high resolution and high efficiency of scanning.

The detailed description of the specific embodiments below will make it easier to understand the purpose, technical content, characteristics and effects of this creation.

In order to solve the problems of the previous technology, the creator has gone through years of research and development to improve the shortcomings of the existing products. The follow-up will introduce in detail how this creation uses an all-fiber 3D tomography system to achieve the most efficient functional demands.

Optical coherence tomography (Optical Coherence Tomography, OCT) can produce non-invasive three-dimensional deep images of wafers or skin tissues. The phase change produced by the coincidence of the reflected beams forms an interference phenomenon, which is used to form a three-dimensional deep image of the tissue to be inspected, but the interference image quality of traditional Optical Coherence Tomography (OCT) or the object to be inspected 3D information still needs to be improved.

Please refer to the first picture. The first picture is a block diagram of the all-fiber 3D tomographic scanning system created by the author. As shown in the figure, the all-fiber 3D tomography system 100 of this disclosure adopts all-fiber lines to construct the entire optical system to give full play to the advantages of optical fibers. Keep the depth and thickness information of the object to be observed. The all-fiber 3D tomography system 100 includes a frequency-sweeping laser 110 , a first optical coupler 120 , a first optical scanning module 130 , a second optical scanning module 140 , a second optical coupler 150 and a balance detector 160 .

Further, the frequency-sweeping laser 110 is used to emit laser light of different wavelengths at different times (the spectrum is quite wide), and the light source of the frequency-sweeping laser 110 is a low coherence collimated light source (Low Coherence Light Source) , which is mainly used to generate an initial beam, which can achieve very high resolution. The first optical coupler 120 is connected to the frequency-sweeping laser 110 by an optical fiber, and the first optical coupler 120 is used for receiving the initial incident light IL emitted by the frequency-sweeping laser 110, and splitting the initial incident light IL into The first incident light TL1 and the second incident light TL2, wherein the light quantity of the first incident light TL1 is 40 to 60 times that of the second incident light TL2, and in this embodiment is 49 times to operate, but not 49 times the limit. The first optical scanning module 130 is connected to the first optical coupler 120 with an optical fiber to receive the first incident light TL1, wherein the first incident light TL1 is directed to the object to be observed TA to generate the first reflected light BL1, wherein the object to be observed TA Depending on the actual usage, it can be wafers, skins or other items.

In addition, the second optical scanning module 140 is connected to the first optical coupler 120 by an optical fiber to receive the second incident light TL2 , wherein the second incident light TL2 is directed to a plane mirror MA to generate the second reflected light BL2 . The above-mentioned first incident light TL1 and second incident light TL2 reach the object to be observed TA and the plane mirror MA at the same time respectively, or arrive at substantially the same time. The second optical coupler 150 is connected to the first optical scanning module 130 and the second optical scanning module 140 to combine the first reflected light BL1 and the second reflected light BL2 respectively, wherein the second optical coupler 150 The two output ports output the first target light PL1 and the second target light PL2 with the same light quantity, and the first target light PL1 and the second target light PL2 have an optical interference effect with each other. The first reflected light BL1 and the second reflected light BL2 reach the second optical coupler 150 at the same time. The balance detector 160 is connected to the two output ports of the second optical coupler 150 with an optical fiber to receive the first target light PL1 and the second target light PL2, and output an optical measurement signal TML after signal processing, which is Interferometric images with 3D information. According to the above description, it can be seen that the all-fiber 3D tomography system 100 of the present invention uses the technology of capturing optical signals to obtain images and adopts an all-fiber circuit structure, which can quickly perform line or area scanning on optical scattering media such as biological tissues. to obtain high-resolution 3D images.

Next, the all-fiber three-dimensional tomography system 100 will be further described in detail.

Please refer to Figure 2, which is a schematic diagram of the detailed blocks of the all-fiber 3D tomographic scanning system created by the author. The first optical scanning module 130 includes a first optical circulator 132 , a first optical collimator 134 , a first convex lens 136 and an electronically controlled attenuator 138 . The first optical circulator 132 is connected to the first optical coupler 120 by an optical fiber to receive the first incident light TL1 , wherein the first incident light TL1 enters from the first port of the first optical circulator 132 and exits from the second port. The first light collimator 134 is connected to the second port of the first optical circulator 132 with an optical fiber to receive the first incident light TL1, and the first light collimator is used to convert the divergent light of the first incident light TL1 into Parallel light. The first convex lens 136 for focusing is arranged in front of the first light collimator 134, wherein the first incident light TL1 will pass through the first light collimator 134 and pass through the first convex lens 136 to the object to be observed TA, so as to A first reflected light ray BL1 is generated. The input port of the electronically controlled attenuator 138 is connected to the third port of the first optical circulator 132 by an optical fiber to receive the first reflected light BL1 and attenuate it according to an attenuation parameter value, that is, reduce the light quantity. The attenuation parameter value of the electronically controlled attenuator 138 is manually or automatically set according to the type of the object TA to be observed, so as to flexibly adjust the quantity of the first reflected light BL1, thereby optimizing the entire all-fiber 3D tomography system 100 .

In addition, the second optical scanning module 140 includes a second optical circulator 142 , a second optical collimator 144 and a second convex lens 146 . The second optical circulator 142 is connected to the first optical coupler 120 by an optical fiber to receive the second incident light TL2, wherein the second incident light TL2 enters from the first port of the second optical circulator 142 and exits from the second port. The second optical collimator 144 is connected to the second port of the second optical circulator 142 with an optical fiber to receive the second incident light TL2, and the second optical collimator 144 is used to convert the divergent light of the second incident light TL2 into parallel Light. The second convex lens 146 for focusing is arranged in front of the second light collimator 144, wherein the second incident light TL2 will pass through the second light collimator 144 and pass through the second convex lens 146 to a plane mirror MA to generate The second reflected ray BL2. Next, the two input ports of the second optical coupler 150 are respectively connected to the output port of the electronically controlled attenuator 138 and the third port of the second optical circulator 142 with optical fibers so as to separate the first reflected light BL1 and the second reflected light BL2 is merged.

From the above, it can be seen that in the system environment where the optical fiber line is used as the main connection line of the all-fiber 3D tomography system 100, the light paths of the first incident light TL1 and the second incident light TL2 are equivalent and the same, and the first reflected light BL1 It is also equivalent to the ray path of the second reflected ray BL2. Among them, more than 90% of the laser energy is concentrated on the sample, and only a single wavelength is output in an instant. The laser energy is held by a single wavelength, unlike traditional OCT laser energy that is shared by multiple wavelengths. Therefore, the final detection of this creation The interference image will also be better than the interference image of traditional OCT.

The tomographic scanning system using all optical fiber lines in this creation can be applied to the optical coherent tomographic scanning of non-metallic objects. For example, the invention can be applied to defect inspection and dimensional metrology of non-metallic objects such as wafers, transparent glue, glass or plastic films in the semiconductor manufacturing industry. In this invention, due to the high admissibility of optics, micron or even sub-micron size information of the entire object to be observed can be obtained. In addition, by using this creation, it is also possible to check the flatness, surface roughness or film thickness of the film surface, and other information about non-metallic objects can be obtained by constructing a 3D image.

To sum up, the all-fiber 3D tomography system disclosed in this creation can bring the following effects: 1. It can quickly perform line or surface scanning on optical scattering media such as biological tissues to obtain high-resolution three-dimensional images; 2. It is easier and more accurate to set up the entire optical tomography system through fiber optic lines; and 3. It has high elastic expansion capability, high resolution and high efficiency of scanning.

Only the above-mentioned ones are only preferred embodiments of this creation, and are not used to limit the scope of implementation of this creation. Therefore, all equal changes or modifications based on the characteristics and spirit described in the scope of application for this creation shall be included in the scope of patent application for this creation.

100: All-fiber 3D tomography system 110:Sweep frequency laser 120: The first optocoupler 130: The first optical scanning module 132: The first optical circulator 134: The first light collimator 136: The first convex lens 138: Electric control attenuator 140: Second optical scanning module 142: Second optical circulator 144: Second light collimator 146: second convex lens 150: Second optocoupler 160:Balance detector IL: initial incident ray TL1: first incident ray TL2: second incident ray BL1: first reflected ray BL2: second reflected ray PL1: first target ray PL2: second target ray TML: optical measurement signal TA: object to be observed MA: plane mirror

The first picture is a block diagram of the all-fiber 3D tomographic scanning system created by the author. The second picture is a schematic diagram of the detailed blocks of the all-fiber 3D tomographic scanning system created by the author.

100: All-fiber 3D tomography system

110:Sweep frequency laser

120: The first optocoupler

130: The first optical scanning module

132: The first optical circulator

134: The first light collimator

136: The first convex lens

138: Electric control attenuator

140: Second optical scanning module

142: Second optical circulator

144: Second light collimator

146: second convex lens

150: Second optocoupler

160:Balance detector

IL: initial incident ray

TL1: first incident ray

TL2: second incident ray

BL1: first reflected ray

BL2: second reflected ray

PL1: first target ray

PL2: second target ray

TML: optical measurement signal

TA: object to be observed

MA: plane mirror

Claims (7)

An all-fiber three-dimensional tomographic scanning system, especially for high-speed three-dimensional tomographic scanning of an object to be observed, the all-fiber three-dimensional tomographic scanning system includes: a frequency-sweeping laser, which is used to emit laser light of different wavelengths; The first optical coupler is connected to the frequency-sweeping laser with an optical fiber, and the first optical coupler is used to receive an initial incident light emitted by the frequency-sweeping laser and split it into a first incident light and a second incident light, wherein the light quantity of the first incident light is 40 to 60 times that of the second incident light; a first optical scanning module, which is connected to the first optical coupler with an optical fiber to receiving the first incident light, wherein the first incident light is directed towards the object to be observed to generate a first reflected light; a second optical scanning module, which is connected to the first optical coupler with an optical fiber to receive the The second incident light, wherein the second incident light is sent to a plane mirror to generate a second reflected light; a second optical coupler, which is connected to the first optical scanning module and the second optical scanning module with an optical fiber to combine the first reflected light and the second reflected light respectively, wherein the two output ports of the second optical coupler output a first target light and a second target light of the same light quantity and optically interfere with each other effect; and a balance detector, which is connected to the two output ports of the second optical coupler with an optical fiber, to receive the first target light and the second target light, and output an optical measurement after signal processing Signal. The all-fiber 3D tomographic scanning system as described in claim 1, wherein the first optical scanning module includes: a first optical circulator, which is connected to the first optical coupler with an optical fiber to receive the first incident light, wherein the first incident light enters from a first port of the first optical circulator and exits from a second port; A first optical collimator, which is connected to the second port of the first optical circulator with an optical fiber, the first optical collimator is used to convert the divergent light of the first incident light into parallel light; a first convex lens , which is arranged in front of the first light collimator, wherein the first incident light will pass through the first light collimator and pass through the first convex lens to the object to be observed, so as to generate a first reflected light ; and an electronically controlled attenuator, the input port of which is connected to the third port of the first optical circulator by optical fiber to receive the first reflected light and attenuate it according to an attenuation parameter value. The all-fiber three-dimensional tomographic scanning system as described in Claim 2, wherein the second optical scanning module includes: a second optical circulator, which is connected to the first optical coupler with an optical fiber to receive the second incident light, Wherein the second incident light enters from the first port of the second optical circulator and exits from the second port; a second optical collimator is connected to the second port of the second optical circulator with an optical fiber, the The second light collimator is used to convert the divergent light of the second incident light into parallel light; and a second convex lens, which is arranged in front of the second light collimator, wherein the second incident light will pass through the first light collimator The two light collimators are sent to a plane mirror through the second convex lens to generate two first reflected light rays. The all-fiber three-dimensional tomographic scanning system as described in claim 3, wherein the two input ports of the second optical coupler are respectively connected to the output port of the electronically controlled attenuator and the third port of the second optical circulator with optical fibers to Combining the first reflected light and the second reflected light respectively. The all-fiber three-dimensional tomographic scanning system according to claim 1, wherein the first incident light and the second incident light respectively reach the object to be observed and the plane mirror at the same time. The all-fiber three-dimensional tomographic scanning system according to claim 1, wherein the first reflected light and the second reflected light reach the second optical coupler at the same time. The all-fiber three-dimensional tomographic scanning system as described in Claim 2, wherein the attenuation parameter value of the electronically controlled attenuator is set manually or automatically according to the type of the object to be observed.

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