JP2018091722A - Optical coherence tomographic device and optical coherence tomographic method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical coherence tomographic device and an optical coherence tomographic method that enable continuous change of a lateral resolution and a depth of focus during observation.SOLUTION: An optical coherence tomographic device comprises: an optical fiber for guiding inspection light; a collimated light generating unit that makes the inspection light emitted from a tip end of the optical fiber incident thereon and outputs the inspection light as collimated light; and a controller for controlling the collimated light generating unit on the basis of an instruction given by an operator. The collimated light generating unit is then configured to be able to continuously change a beam diameter of the inspection light outputted as the collimated light in accordance with the control performed by the controller.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an optical coherence tomography apparatus and an optical coherence tomography method.

  As an apparatus for measuring the depth of an eyeball, there is an optical coherence tomography (OCT) that generates a tomographic image of an eyeball from depth information. Particularly, recently, OCT using a wavelength scanning laser capable of acquiring a tomographic image with high speed and high sensitivity has been actively used.

  Patent Document 1 describes an eyeball measuring device (OCT) that can further increase the accuracy of eyeball measurement. In this eyeball measuring device, the eyeball measuring device includes two optical systems of an object side telecentric optical system and an image side telecentric optical system, and each optical system is an eyeball to be measured among lenses arranged in each optical system. Share the lens closest to the lens. Then, the optical system switching unit of the eyeball measuring device switches between the incident light incident on the object side telecentric optical system and the incident light incident on the image side telecentric optical system.

  Currently used optical coherence tomography apparatuses (Optical Coherence Tomography, hereinafter also referred to as “OCT”) have inspection objects (for example, eyeballs, teeth, etc.) and their optimal observation ranges limited for each apparatus. ing. This is because the wavelength of the inspection light employed in each device and the characteristics of the optical system such as a lens are fixed to some extent and cannot be changed greatly during observation.

Patent Document 2 discloses an OCT system capable of adjusting a lateral resolution (also referred to as azimuth resolution) by switching a plurality of collimating lenses (29 ₁ , 29 ₂ ) having different focal lengths.
Patent Document 3 describes a surgical microscope having a collimating optical system 130 having a driving device 133 and having a variable magnification and a compact configuration. Patent Document 4 describes a wavelength scanning optical coherence tomography apparatus that can acquire a tomographic image in a manner desired by an operator without requiring high performance of the apparatus or addition of a complicated device. Has been.

Japanese Patent No. 5970682 Japanese Patent No. 5941085 Japanese Patent No. 5213417 Japanese Patent No. 5987186

OCT is mainly used for the purpose of observing a human body part such as an eyeball or a tooth in real time. Then, if the process of changing the observation range and resolution becomes discontinuous (discontinuous), if the human body part to be inspected moves during the change, the part that was going to be observed You may lose sight.
Therefore, in the technical field of OCT, there is a demand for a function capable of seamlessly coexisting wide-area observation and local observation by continuously changing the lateral resolution and the focal depth during observation.

  In view of the problems as described above, an object of the present invention is to provide an optical coherence tomography apparatus and an optical coherence tomography method capable of continuously changing the lateral resolution and the depth of focus during observation.

  According to the first aspect of the present invention, an optical coherence tomography apparatus receives an optical fiber that guides inspection light and the inspection light emitted from the tip of the optical fiber, and outputs the inspection light as collimated light. A collimated light generating unit that controls the collimated light generating unit based on an operation by an operator. The collimated light generation unit can continuously change the beam diameter of the inspection light output as the collimated light according to control from the control unit.

  Further, according to the second aspect of the present invention, the collimated light generation unit includes a variable focus lens disposed at a position away from the tip of the optical fiber, and from the tip of the optical fiber to the focus variable lens. And a lens position changing unit that can change the distance continuously. The control unit changes the focal length of the variable focus lens so that the distance from the tip of the optical fiber to the variable focus lens matches the focal length of the variable focus lens.

  According to the third aspect of the present invention, the collimated light generation unit is configured to receive a fixed collimator lens disposed at a position away from the tip of the optical fiber, and collimated light generated through the fixed collimator lens. A first focus variable lens, and a second focus variable lens disposed at a position away from the first focus variable lens by a predetermined distance.

  According to the fourth aspect of the present invention, the control unit includes a first focal length that is a focal length of the first variable focus lens and a second focal length that is a focal length of the second variable focus lens. The first focal length and the second focal length are changed so that the sum of the first focal length matches the predetermined distance.

  According to the fifth aspect of the present invention, an optical coherence tomography method includes an optical fiber that guides inspection light, and the inspection light emitted from the tip of the optical fiber is incident to collimate the inspection light. An optical coherence tomography apparatus using an optical coherence tomography apparatus comprising: a beam of the inspection light output as the collimated light by controlling the collimated light generation unit The diameter can be changed continuously.

  According to the optical coherence tomography apparatus and the optical coherence tomography method described above, the lateral resolution and the focal depth can be continuously changed during observation.

1 is a diagram illustrating an overall configuration of an optical coherence tomography apparatus according to a first embodiment. It is a figure which shows the structure of the collimated light production | generation unit which concerns on 1st Embodiment. It is a figure explaining the function of the collimated light production | generation unit which concerns on 1st Embodiment. It is a figure which shows the structure of the collimated light production | generation unit which concerns on 2nd Embodiment. It is a 1st figure explaining the further function of the collimated light production | generation unit which concerns on 2nd Embodiment. It is a 2nd figure explaining the further function of the collimated light production | generation unit which concerns on 2nd Embodiment.

<First Embodiment>
The optical coherence tomography apparatus according to the first embodiment will be described below with reference to FIGS.

(overall structure)
FIG. 1 is a diagram illustrating an overall configuration of an optical coherence tomography apparatus according to the first embodiment.
As shown in FIG. 1, an optical coherence tomography apparatus 1 (wavelength scanning optical coherence tomography apparatus) includes a wavelength scanning light source unit 10, optical couplers 110 to 111, optical circulators 120 to 121, and a collimated light generation unit. 130, 131, objective lenses 132 and 133, the movable mirror 14, the reference mirror 15, the differential photodetector 16, and the computer 20.

The wavelength scanning light source unit 10 includes a wavelength scanning light source 100 and a wave number equidistant clock output unit 101.
The wavelength scanning light source 100 outputs inspection light P (wavelength scanning light) in which the wavelength continuously changes according to the time change (the wavelength is scanned). The output inspection light P is transmitted to the optical coupler 110 through an optical fiber. The wavelength scanning light source 100 repeatedly outputs the inspection light P at a predetermined repetition rate called “A-scan rate” (for example, about 500 kHz).
The wave number equal interval clock output unit 101 outputs a k-clock signal K which is a clock signal corresponding to the output of the inspection light P. Specifically, the k-clock signal K repeats rising and falling alternately at the timing when the wave number k of the inspection light P changes by a predetermined equal change amount (wave number change amount Δk) in the process of wavelength scanning. This is a clock signal.
The wave number equal interval clock output unit 101 takes, for example, a part of the inspection light P output from the wavelength scanning light source 100 and inputs it to a Mach-Zehnder interferometer, a photodetector, or the like, thereby causing a k-clock signal K. (See, for example, Patent Document 4).
Further, the wavelength scanning light source unit 10 outputs a start signal T (trigger signal) indicating the timing at which the wavelength scanning of the inspection light P is started.

  The optical coupler 110 and the optical coupler 111 are elements that distribute input light at a specified ratio. The inspection light P input from the wavelength scanning light source unit 10 to the optical coupler 110 is distributed at a predetermined ratio and transmitted to the optical circulator 120 and the optical circulator 121, respectively.

The optical circulators 120 and 121 are elements that regulate and output the light path in one direction.
The inspection light P input from the optical coupler 110 to the optical circulator 120 passes through the collimated light generation unit 130 (described later), the movable mirror 14 and the objective lens 132. ). As the angle of the movable mirror 14 changes, the inspection light P is irradiated to a desired position in the object X. The object reflected light Px formed by reflecting the inspection light P with the imaging object X is transmitted to the optical coupler 111 via the optical circulator 120.
On the other hand, the inspection light P input from the optical coupler 110 to the optical circulator 121 is applied to the reference mirror 15 via a collimated light generation unit 131 (described later) and an objective lens 133. The reference reflected light Pm obtained by reflecting the inspection light P by the reference mirror 15 is transmitted to the optical coupler 111 via the optical circulator 121.
The object reflected light Px reflected and returned by the photographic object X and the reference reflected light Pm reflected and returned by the reference mirror 15 are combined by the optical coupler 111, so that the object reflected light is reflected. Interference light between Px and reference reflected light Pm is generated.

The collimated light generation unit 130 receives the inspection light P emitted from the tip Q of the optical fiber connected to the optical circulator 120, and outputs the inspection light P as collimated light (parallel light). The collimated light (inspection light P) output from the collimated light generation unit 130 is applied to the object X through the movable mirror 14 and the objective lens 132.
The collimated light generation unit 131 receives the inspection light P emitted from the tip Q of the optical fiber connected to the optical circulator 121, and outputs the inspection light P as collimated light (parallel light). The collimated light (inspection light P) output from the collimated light generation unit 131 is applied to the reference mirror 15 through the objective lens 133.
The collimated light generation units 130 and 131 can continuously change the beam diameter of the inspection light P output as collimated light in accordance with control from the computer 20 (described later). The collimated light generation units 130 and 131 have the same structure. A specific configuration of the collimated light generation units 130 and 131 will be described later.

  The differential photodetector 16 inputs an interference light between the object reflected light Px and the reference reflected light Pm as a differential signal, and is an interference signal that is an electrical signal indicating the intensity (amplitude) of the interference light from which the in-phase noise is removed. C is output. The interference signal C is input to an A / D converter 21 mounted on the computer 20.

The computer 20 includes an A / D converter 21, a CPU 22 (control unit), and an operation unit 23.
The A / D converter 21 samples the interference signal C (intensity of interference light) and converts it into sampling data (digital data). Specific modes of the A / D converter 21 according to this embodiment will be described later.

The CPU 22 controls the overall operation of the optical coherence tomography apparatus 1 by reading and operating a dedicated program prepared in advance. In particular, the CPU 22 according to the present embodiment functions as a tomographic image generation unit that generates tomographic image data indicating the tomographic state of the imaging target X based on the sampling data acquired through the A / D converter 21.
Further, the CPU 22 receives an operation of an operator (operator) from an operation unit 23 (described later), and outputs a control signal toward the collimated light generation units 130 and 131.

  The operation unit 23 is, for example, a keyboard, a mouse, a touch sensor, or the like, and is a user interface that receives an operation by an operator of the optical coherence tomography apparatus 1.

The overall configuration of the optical coherence tomography apparatus 1 according to the first embodiment has been described above. In the present embodiment, the optical coherence tomography apparatus 1 has been described as a wavelength scanning (sweep) optical coherence tomography apparatus (Swept source OCT; SS-OCT) having the wavelength scanning light source 100. The embodiment is not limited to this aspect.
For example, an optical coherence tomography apparatus 1 according to another embodiment is a spectral domain optical coherence tomography apparatus (Spectral-domain OCT; SD-OCT) that detects in Fourier space using a fixed wavelength light source and a spectroscope. There may be.

(Configuration of collimated light generation unit)
FIG. 2 is a diagram illustrating a configuration of the collimated light generation unit according to the first embodiment.
As shown in FIGS. 2A and 2B, the collimated light generating unit 130 includes a variable focus lens 1300 and a lens position changing unit 1301.

The variable focus lens 1300 can continuously change the focal length f as desired within a predetermined range in accordance with a control signal from the CPU 22 (FIG. 1).
The variable focus lens 1300 is disposed at a position away from the tip Q of the optical fiber. Specifically, the variable focus lens 1300 is arranged so that its optical axis coincides with the axis L shown in FIG. Here, the axis L is the central axis of the light beam (expansion of the inspection light P) emitted from the tip Q of the optical fiber.
The lens position changing unit 1301 is a so-called linear motion mechanism, and continuously translates the position of the variable focus lens 1300 according to a control signal from the CPU 22. The lens position changing unit 1301 includes, for example, a guide rail and a motor (not shown). The lens position changing unit 1301 moves along the axis L while maintaining the posture of the variable focus lens 1300. As described above, the lens position changing unit 1301 can continuously change the distance from the tip of the optical fiber to the variable focus lens 1300.

Next, the contents of control performed by the CPU 22 on the collimated light generation unit 130 will be described with reference to FIGS. 2 (a) and 2 (b).
The CPU 22 changes the focal length f of the variable focus lens 1300 so that the distance D from the tip Q of the optical fiber to the variable focus lens 1300 matches the focal length f of the variable focus lens. The “distance D from the tip Q of the optical fiber to the variable focal lens 1300” strictly means the position from the front end Q of the optical fiber to the center of the variable focal lens 1300.

For example, as shown in FIG. 2A, the CPU 22 outputs a predetermined control signal toward the variable focus lens 1300, and sets the focal length f of the variable focus lens 1300 to a certain focal length f1 (f = f1). In this case, the CPU 22 further outputs a control signal toward the lens position changing unit 1301 so that the distance D from the tip Q of the optical fiber to the variable focus lens 1300 matches the focal length f1 (D = f1, FIG. 2). (See (a)).
In this case, the inspection light P emitted from the tip Q of the optical fiber passes through the variable focus lens 1300 and is then output as collimated light (parallel light) having a beam diameter d1.

Further, as shown in FIG. 2B, the CPU 22 outputs a predetermined control signal toward the variable focal lens 1300, and the focal length f of the variable focal lens 1300 is larger than the focal length f1. (F2> f1) is set (f = f2). In this case, the CPU 22 further outputs a control signal toward the lens position changing unit 1301 so that the distance D from the tip Q of the optical fiber to the variable focus lens 1300 matches the focal length f2 (D = f2, FIG. 2). (See (b)).
In this case, the inspection light P emitted from the tip Q of the optical fiber passes through the variable focus lens 1300 and is then output as collimated light (parallel light) having a beam diameter d2. In this case (when f = f2 and D = f2), the beam diameter d2 is larger than the beam diameter d1 when f = f1 and D = f1.
As described above, the collimated light generation unit 130 continuously changes the focal length f of the variable focus lens 1300 and the distance D from the tip Q of the optical fiber to the variable focus lens 1300 to match the collimated light. It is possible to continuously change the beam diameter of the inspection light P.

The collimated light generation unit 131 for guiding the inspection light P to the reference mirror 15 has the same configuration as the collimated light generation unit 130 shown in FIG. In other words, the collimated light generation unit 131 includes a variable focus lens 1300 and a lens position changing unit corresponding to the lens position changing unit 1301 shown in FIG.
Further, the CPU 22 controls the collimated light generation unit 131 in the same manner as the collimated light generation unit 130. That is, when the beam diameter of the inspection light P output from the collimated light generation unit 130 is “d1”, the beam diameter of the inspection light P output from the collimation light generation unit 131 is also controlled to be “d1”. . By doing in this way, the optical path lengths of the object reflected light Px and the reference reflected light Pm can always be the same.

(Function of collimated light generation unit)
FIG. 3 is a diagram illustrating the function of the collimated light generation unit according to the first embodiment.
FIG. 3 shows the relationship between the object X and the objective lens 132. The operation of changing the beam diameter of the inspection light P, which is collimated light, using the collimated light generation unit 130 will be described with reference to FIG.

  The lateral resolution Δx and the depth of focus b in observation and photographing through an objective lens such as OCT are calculated as in equations (1) and (2), respectively.

In equations (1) and (2), “f” is the focal length of the objective lens 132, “d” is the beam diameter of the inspection light P, and “λ” is the center wavelength of the inspection light P.
According to Equation (1), in order to improve the lateral resolution Δx, an objective lens having a small “f” (focal length) may be used, or “d” (beam diameter) may be increased. However, as shown in Expression (2), when “f” is decreased or “d” is increased, the depth of focus b is decreased. Therefore, the lateral resolution Δx and the depth of focus b are in a trade-off relationship. The focal depth b corresponds to an allowable amount of deviation in the distance between the objective lens and the photographing object X with respect to the focal length f, and the larger the depth, the easier it is to observe in a wide range.

When changing the lateral resolution Δx and the focal depth b, if the focal length f of the objective lens 132 is to be changed, it is necessary to change the position of the photographing object X each time. Then, the observation range cannot be changed at high speed and continuously. Therefore, in the present embodiment, the focal length f of the objective lens 132 is fixed at “ft”, and instead, “d” (beam diameter) is changed to change the lateral resolution Δx and the focal depth b. And
As shown in FIG. 3A, the depth of focus b and the lateral resolution Δx are increased by setting the beam diameter d of the inspection light P to d1 (<d2). Thereby, the operator can perform wide-area observation.
Further, as shown in FIG. 3B, by setting the beam diameter d of the inspection light P to d2 (> d1), the lateral resolution Δx and the focal depth b are reduced. Thereby, the operator can perform local observation.
In any case, it is not necessary to change the distance D ′ (= ft) from the objective lens 132 to the observation surface of the object X (see FIGS. 3A and 3B).

(Function, effect)
As described above, the optical coherence tomography apparatus 1 according to the first embodiment includes the collimated light generation units 130 and 131, so that the beam diameter of the collimated light (inspection light P) supplied to the objective lens 132 is continuously desired. Can be changed. As a result, the lateral resolution Δx and the focal depth b can be changed continuously (seamlessly) without changing the focal position of the objective lens 132, and both wide-area observation and local observation can be achieved.

<Second Embodiment>
Next, an optical coherence tomography apparatus according to the second embodiment will be described with reference to FIGS.

(Configuration of collimated light generation unit)
FIG. 4 is a diagram illustrating a configuration of a collimated light generation unit according to the second embodiment.
Since the overall configuration of the optical coherence tomography apparatus 1 according to the second embodiment is the same as that of the first embodiment (FIG. 1), illustration is omitted. The optical coherence tomography apparatus 1 according to the second embodiment is different from the first embodiment in the configuration of the collimated light generation units 130 and 131.

  As shown in FIGS. 4A and 4B, the collimated light generation unit 130 according to the second embodiment includes two variable focus lenses 1300 a and 1300 b and a fixed collimator lens 1302.

  The fixed collimating lens 1302 is a normal lens having a fixed focal length, and is disposed at a position away from the tip Q of the optical fiber. The fixed collimating lens 1302 is arranged so that its optical axis coincides with the axis L shown in FIG. The distance from the tip Q of the optical fiber to the fixed collimating lens 1302 matches the focal length of the fixed collimating lens 1302. Therefore, the inspection light P emitted from the tip Q of the optical fiber is once shaped into collimated light by the fixed collimating lens 1302.

  As shown in FIGS. 4A and 4B, the variable focus lens 1300a (first variable focus lens) and the variable focus lens 1300b (second variable focus lens) have their optical axes aligned with the axis L. Be placed. The variable focus lens 1300b is disposed at a position away from the variable focus lens 1300a by a predetermined distance D0. The variable focus lenses 1300a and 1300b are fixedly installed.

The variable focus lens 1300a receives the collimated light (inspection light P) generated through the fixed collimator lens 1302, and the incident inspection light P is separated by a set focal distance f (<D0) (collection point). Light is collected at the light spot R).
The variable focus lens 1300b receives the inspection light P emitted from the variable focus lens 1300a, and again emits the inspection light P as collimated light.
The variable focus lenses 1300a and 1300b can independently and continuously change the focal length f in accordance with a control signal from the CPU 22 (FIG. 1).

In the CPU 22 according to the second embodiment, the sum of the focal length (first focal length fa) of the variable focus lens 1300a and the focal length (second focal length fb) of the variable focus lens 1300b matches the predetermined distance D0. As described above, the first focal length and the second focal length are changed.
Hereinafter, details of the control of the CPU 22 according to the second embodiment will be described with reference to the examples shown in FIGS.

For example, as shown in FIG. 4A, the CPU 22 outputs a predetermined control signal toward the variable focus lens 1300a, and sets the first focal length fa of the variable focus lens 1300a to “fa1” (fa1). = Fa1). In this case, the CPU 22 further outputs a predetermined control signal toward the variable focus lens 1300b, and sets the second focal length fb of the variable focus lens 1300b to “fb1” (fb = fb1).
Here, the CPU 22 determines that the sum of the first focal length fa (= fa1) of the variable focus lens 1300a and the second focal length fb (= fb1) of the variable focus lens 1300b is from the variable focus lens 1300a to the variable focus lens 1300b. The first focal length fa and the second focal length fb are changed so as to coincide with the distance D0 (fa1 + fb1 = D0).

  In this way, the inspection light P is first condensed at a condensing point R at a position away from the variable focus lens 1300a by a distance Da = fa1. The distance Db from the condensing point R to the variable focus lens 1300b matches the second focal length fb (= fb1). Therefore, as a result of passing through the variable focus lens 1300a and the variable focus lens 1300b, the inspection light P is shaped into collimated light having a beam diameter d1.

Further, as shown in FIG. 4B, the CPU 22 outputs a predetermined control signal toward the variable focus lens 1300a, and the first focal length fa of the variable focus lens 1300a is smaller than “fa1”. It is set to fa2 ″ (fa = fa2 <fa1). In this case, the CPU 22 further outputs a predetermined control signal toward the variable focus lens 1300b, and sets the second focal length fb of the variable focus lens 1300b to “fb2” (fb = fb2).
Here, the CPU 22 sets the first focal length fa and the second focal length fb so that the sum of the first focal length fa (= fa2) and the second focal length fb (= fb2) matches the distance D0. Change (fa2 + fb2 = D0). In this case, the second focal length fb is increased by the amount corresponding to the decrease in the first focal length fa, so that fb2> fb1.

The inspection light P is first condensed at a condensing point R at a position away from the focus variable lens 1300a by a distance Da = fa2 (<fa1). The distance Db from the condensing point R to the variable focus lens 1300b matches the second focal length fb (= fb2> fb1). Therefore, as a result of passing through the variable focus lens 1300a and the variable focus lens 1300b, the inspection light P is shaped into collimated light having a beam diameter d2.
Here, the position of the condensing point R in the case of FIG. 4B is closer to the variable focus lens 1300a than in the case of FIG. Then, the distance Db from the condensing point R to the variable focus lens 1300b becomes long, and the beam diameter of the collimated light emitted from the variable focus lens 1300b increases accordingly (d2> d1).

  Also in the second embodiment, as in the first embodiment, the depth of focus b and the lateral resolution Δx can be increased by setting the beam diameter d of the inspection light P to d1 (<d2). Thereby, the operator can perform wide-area observation. Further, by setting the beam diameter d of the inspection light P to d2 (> d1), the lateral resolution Δx and the depth of focus b can be reduced. Thereby, the operator can perform local observation (refer to formulas (1) and (2) and FIGS. 3 (a) and 3 (b)).

The collimated light generation unit 131 (a collimated light generation unit for guiding the inspection light P to the reference mirror 15, see FIG. 1) according to the second embodiment is a collimated light generation unit shown in FIGS. 4 (a) and 4 (b). The configuration is equivalent to 130. That is, the collimated light generating unit 131 includes two variable focus lenses corresponding to the variable focus lenses 1300a and 1300b and the fixed collimator lens 1302 and the fixed collimator lens shown in FIGS.
Further, the CPU 22 according to the second embodiment controls the collimated light generation unit 131 in the same manner as the collimated light generation unit 130. That is, when the beam diameter of the inspection light P output from the collimated light generation unit 130 is “d1”, the beam diameter of the inspection light P output from the collimation light generation unit 131 is also controlled to be “d1”. . By doing in this way, the optical path lengths of the object reflected light Px and the reference reflected light Pm can always be the same.

(Function, effect)
As described above, the collimated light generation unit 130 according to the second embodiment includes the fixed collimator lens 1302 and the two variable focus lenses 1300a and 1300b. Further, the CPU 22 changes the focal lengths (first focal length fa, second focal length fb) of the two variable focus lenses 1300a, 1300b so as to always satisfy the condition of “fa + fb = D0”.
By doing so, the beam diameter of the collimated light (inspection light P) can be continuously changed without using a driving mechanism such as the lens position changing unit 1301 (FIG. 2). Therefore, since mechanical drive is not required, the observation range can be changed at a higher speed. Further, the reliability of the device can be improved by eliminating the drive mechanism.

(Further functions of the collimated light generation unit)
5 and 6 are first and second diagrams, respectively, for explaining further functions of the collimated light generating unit according to the second embodiment.
Further functions of the collimated light generation unit 130 according to the second embodiment will be described with reference to FIGS.

  The CPU 22 according to the second embodiment may perform control so as not to satisfy the condition of “fa + fb = D0”.

For example, when the focal length (first focal length fa) of the variable focus lens 1300a is “fa1,” and the focal length (second focal length fb) of the variable focus lens 1300b is “fb1,” “fa1 + fb1 = As described above, collimated light having a beam diameter d1 that satisfies D0 ″ is formed (see FIG. 4A). However, as shown in FIG. 5A, the CPU 22 may not set the focal length of the variable focus lens 1300b to “fb1” but to “fb3” (fb3> fb1) larger than “fb1”. In this case, “fa1 + fb3> D0”.
Then, since the variable focus lens 1300b enters the inspection light P from the condensing point R existing at a position closer to the focal length fb3 of the variable focus lens 1300b itself, the inspection light P does not become collimated light, but divergent light ( The beam diameter increases as the distance from the variable focus lens 1300b increases.

The inspection light P (diverging light) formed as shown in FIG. 5A enters the objective lens 132 via the movable mirror 14 (FIG. 1). FIG. 6A shows the state of the inspection light P (diverging light) around the object X to be imaged.
When the inspection lens P that is diverging light is incident, the objective lens 132 collects light at a position farther than the focal length ft of the objective lens 132. Therefore, the focus can be adjusted when the observation surface of the object X is located at a position farther than the focal length ft of the objective lens 132 (D ′> ft).

Further, as shown in FIG. 5B, the CPU 22 may not set the focal length of the variable focus lens 1300b to “fb1” but to “fb4” (fb4 <fb1) smaller than “fb1”. In this case, “fa1 + fb4 <D0”.
Then, since the variable focus lens 1300b enters the inspection light P from the condensing point R existing at a position closer to the focal length fb4 of the variable focus lens 1300b itself, the inspection light P does not become collimated light, but convergent light ( The light beam becomes narrower as the distance from the variable focus lens 1300b increases.

The inspection light P (converged light) formed as shown in FIG. 5B enters the objective lens 132 through the movable mirror 14 (FIG. 1). FIG. 6B shows the state of the inspection light P (converged light) around the object X to be imaged.
When the inspection light P that is convergent light is incident, the objective lens 132 collects light at a position closer to the focal length ft of the objective lens 132. Therefore, the focus can be adjusted when the observation surface of the object X is located at a position closer than the focal length ft of the objective lens 132 (D ′ <ft).

As described above, according to the collimated light generation unit 130 according to the second embodiment, not only can the observation range be continuously changed by changing the beam diameter, but also the focal length (second focal point) of the variable focus lens 1300b. By adjusting the distance fb), it is possible to correct the positional deviation of the subject X (the deviation of the distance from the objective lens 132).
In the description using FIG. 5, the aspect of adjusting the focal length (second focal length fb) of the variable focal length lens 1300b has been described with respect to the correction of the positional deviation of the object X to be photographed. It is not restricted to an aspect. That is, the CPU 22 according to another embodiment may perform the positional deviation correction of the imaging target object X by changing the focal length (first focal length fa) of the variable focus lens 1300a.

  In the above description, the term “continuous” may mean discrete as long as the operator does not feel inconvenience or inconvenience when switching between wide-area observation and local observation. Shall be included.

  In each of the above-described embodiments, the processes of the various processes of the computer 20 described above are stored in a computer-readable recording medium in the form of a program, and the above-described various processes are performed by the computer reading and executing the program. Processing is performed. The computer-readable recording medium is a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient. Furthermore, the computer 20 may be composed of a single computer, or may be composed of a plurality of computers that are communicably connected.

  As mentioned above, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the invention described in the claims and equivalents thereof in the same manner as included in the scope and gist of the invention.

DESCRIPTION OF SYMBOLS 1 Optical coherence tomography apparatus 10 Wavelength scanning light source unit 100 Wavelength scanning light source 101 Wave number equidistant clock output part 110, 111 Optical coupler 120, 121 Optical circulator 130, 131 Collimated light production | generation unit 1300, 1300a, 1300b Variable focus lens 1301 Lens position Changing unit 1302 Fixed collimating lenses 132 and 133 Objective lens 14 Movable mirror 15 Reference mirror 16 Differential photodetector 20 Computer 21 A / D converter 22 CPU (control unit)
23 Operation part X Object to be photographed

Claims (5)

An optical fiber that guides the inspection light;
A collimated light generation unit that enters the inspection light emitted from the tip of the optical fiber and outputs the inspection light as collimated light; and
A control unit for controlling the collimated light generation unit based on an operation by an operator;
With
The collimated light generation unit is
An optical coherence tomography apparatus capable of continuously changing the beam diameter of the inspection light output as the collimated light in accordance with control from the control unit. The collimated light generation unit is
A variable focus lens disposed at a position away from the tip of the optical fiber;
A lens position changing unit capable of continuously changing the distance from the tip of the optical fiber to the variable focus lens;
With
The controller is
The optical coherence tomography apparatus according to claim 1, wherein the focal length of the variable focus lens is changed so that the distance from the tip of the optical fiber to the variable focus lens matches the focal length of the variable focus lens. . The collimated light generation unit is
A fixed collimating lens disposed at a position away from the tip of the optical fiber;
A first variable focus lens on which collimated light generated through the fixed collimator lens is incident;
A second variable focus lens disposed at a position away from the first variable focus lens by a predetermined distance;
An optical coherence tomography apparatus according to claim 1. The controller is
The first focal length is set such that a sum of a first focal length that is a focal length of the first variable focus lens and a second focal length that is a focal length of the second variable focus lens matches the predetermined distance. The optical coherence tomography apparatus according to claim 3, wherein the second focal length is changed. Light using an optical coherence tomography apparatus comprising: an optical fiber that guides inspection light; and a collimated light generation unit that inputs the inspection light emitted from the tip of the optical fiber and outputs the inspection light as collimated light A coherence tomography method,
An optical coherence tomography method in which the collimated light generation unit is controlled to continuously change the beam diameter of the inspection light output as the collimated light.

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