KR20150043115A - Optical Coherence Tomography Device - Google Patents

Abstract

The present invention relates to a probe for an OCT apparatus installed in one end part of the OCT apparatus. The probe for the OCT apparatus includes an afocal zooming optical system which is formed to be capable of varying an F-number of the probe without changing a focal position of the probe. The present invention provides the OCT apparatus changing resolution of a probe optical system in accordance with requirements to be capable of obtaining image quality suitable for an object to be measured.

Description

OCT device {Optical Coherence Tomography Device}

The present invention relates to a probe capable of changing an F number and an OCT apparatus having the same.

OCT (Optical Coherence Tomography) is a technique for obtaining high-resolution tomographic images by using time difference of light reflected in tissue by transmitting light.

In the OCT apparatus, a low coherence source is branched into a bifurcated arm through a coupler, and the light reflected from each arm is transmitted to a detector to form an interference pattern . The depth information of the sample to be measured can be obtained according to the low coherence interferometry principle (refer to 'OCT Apparatus' in Patent Publication 10-2012-0123265).

OCT devices are used primarily as medical devices for examining tomographic images and cross-sections of ocular biopsies and teeth. A conventional surgical microscope is composed of a light source for irradiating light to the affected part of the patient, an objective lens for enlarging the eyeball of the patient, and an eyepiece lens for visually confirming the enlarged eyeball. However, since such a surgical microscope merely shows the surface image of the eyeball, there is a problem that it is difficult to distinguish between biopsy tissue. To solve this problem, an OCT apparatus has been developed. [Japanese Laid-open Patent Application No. 2009-034480] describes a technique of using an OCT device for ophthalmologic diagnosis.

However, once the horizontal resolution and the depth of focus (DOF) of the OCT apparatus are set to a constant value, it is impossible to change the resolution and the use of the apparatus is limited.

The present invention is to provide an OCT apparatus capable of changing the resolution of a probe optical system as needed to obtain an appropriate image quality suitable for an object to be measured.

In order to solve the above problems, a probe according to an embodiment of the present invention is mounted on one end of an OCT apparatus and is configured to vary the F number of the probe without changing the focus position of the probe And an afocal zoom optical system.

In one embodiment of the present invention, the probe for an OCT apparatus includes a scan lens for correcting a path of light irradiated to the sample to face a sample, and a scan lens disposed adjacent to the scan lens for irradiating parallel light to the scan lens An optical fiber collimator, and an apical zoom optical system disposed between the scan lens and the optical fiber collimator to vary the F number of the probe.

In an embodiment of the present invention, the afocal zoom optical system changes an F number by changing a diameter of light irradiated to the scan lens.

As an example related to the present invention, the afocal zoom optical system includes a zoom lens which moves along an optical axis so as to collect or diverge light.

As an example related to the present invention, the afocal zoom optical system further includes a driving motor connected to the zoom lens to move the zoom lens.

According to another aspect of the present invention, there is provided an eyepiece zoom optical system, comprising: a first lens that focuses light emitted from the optical fiber collimator toward an optical axis; and a second lens that converges light traveling through the first lens toward the optical axis And a third lens that overlaps the second lens and emits light so that the light refracted by the second lens and the second lens is irradiated to the scan lens in the form of parallel light, And changes the diameter of the light incident on the second lens by moving along the optical axis between the lens and the second lens.

According to another aspect of the present invention, there is provided a light source device including a light source for generating light, a coupler for branching the light generated from the light source to proceed to the first arm and the second arm, Wherein the probe comprises a scan lens for correcting a path of light irradiated to the sample so as to face the sample, an optical fiber collimator formed at one end of the first arm to irradiate parallel light to the scan lens, And an apical zoom optical system arranged between the optical fiber collimator and the F number of the probe.

As an example related to the present invention, the first arm irradiates the branched light to a sample and then transmits the light reflected on the sample to a detector, and the second arm irradiates the branched Reflected from the reference surface, and transmits the reflected light to the detector.

As an example related to the present invention, the afocal zoom optical system includes a zoom lens which moves along an optical axis so as to collect or diverge light.

In one embodiment of the present invention, the afocal zoom optical system includes a first lens that focuses the light emitted from the optical fiber collimator toward an optical axis, and a second lens that collects light traveling through the first lens toward the optical axis And a third lens that overlaps the second lens and emits light so that the light refracted by the second lens and the second lens is irradiated to the scan lens in the form of parallel light, The second lens moves along the optical axis to change the diameter of the light incident on the second lens.

The OCT apparatus according to at least one embodiment of the present invention configured as described above is provided with a probe capable of changing the F number of the optical system to change the focus position of the optical system formed on the probe or to lower the image signal- (Depth of focus) without adjusting the resolution and DOF.

1 is a conceptual view of an OCT apparatus according to an embodiment of the present invention;
2 is a conceptual diagram of a horizontal resolution and a DOF that change according to F number change of a probe according to an embodiment of the present invention;
3 is a conceptual view enlarging one end of the first arm shown in Fig.
4A to 4C are conceptual diagrams showing embodiments of an afocal zoom optical system of the present invention.

Hereinafter, an OCT apparatus including a probe and a probe related to the present invention will be described in detail with reference to the drawings. In the present specification, the same or similar reference numerals are given to different embodiments in the same or similar configurations. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

In describing the present invention, the terms first, second, etc. may be used to describe various components, but the components are not limited by the terms. These terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

Where an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, but other elements may be present in between . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it means that no other element exists in between.

1 is a conceptual diagram of an OCT apparatus 100 according to an embodiment of the present invention.

1, the OCT apparatus 100 includes a light source 110, a coupler 120, a first arm 140 and a second arm 131 branched from the coupler 120, a detector 150, And the like.

The OCT apparatus 100 divides the light of the light source 110 into reference light and sample light, and superimposes the sample light reflected on the eye fundus of the eye to be examined and the reference light reflected on the reference object to generate interference light. The detection result is input to the operation control device. The operation control device analyzes the detection signal to form a tomographic image of the fundus.

The light source 110 irradiates light having low coherence. As the light source 110, an SLD (super luminescent diode), a light emitting diode (LED), or the like may be used. Light having low coherence includes light of a near infrared region wavelength and has a temporal coherence length of several tens of micrometers. The light with low coherence has a longer wavelength than the illumination light (wavelength 400 to 800 nm) of the OCT device 100. For example, the light can be determined within a range of about 800 to 1100 nm.

Light generated by the light source 110 is guided to the coupler 120 through the fiber 111. The fiber can be made of single mode fiber or PM fiber (Polarization Maintaining Fiber).

The coupler 120 may function as both means for dividing light (splitter) and means for superimposing light (coupler), but is conventionally referred to as a coupler. In other words, in the specification of the present invention, it is referred to as a coupler, but it means a coupler including a splitter function.

The light split by the coupler 120 travels to the first arm 140 and the second arm 131. The first arm 140 is a sample arm for irradiating light to an object to be measured, and the second arm 131 is a reference arm for irradiating light to a reference object.

Light traveling through the second arm 131 is collimated by the collimator lens 132 and is reflected on the reference surface 131 via a glass block and a density filter (not shown).

The reference light reflected on the reference surface 131 is condensed on the end surface of the second arm 131 by the collimator lens 132 via the density filter and the glass block (not shown) And is guided to the coupler 120.

The glass block and the concentration filter are used as a delay means for adjusting the optical path distance (optical distance) between the reference light and the sample light, and as a dispersion compensating means for matching the dispersion characteristics of the reference light and the sample light.

The concentration filter may act as a dimming filter to reduce the amount of light of the reference light. The density filter may be a rotating ND (Neutral Density) filter. The density filter is rotationally driven by the density filter driving mechanism to adjust the light amount of the reference light.

The reference plane 131 can move in the traveling direction of the reference light. Thus, the optical path distance of the reference light can be secured in correspondence with the length of the object, the working distance, and the like. A drive motor is mounted on the reference surface 131 so that the position can be automatically set.

The sample light split by the coupler 120 travels along the first arm 140. One end of the first arm 140 is equipped with a probe, and the sample light is irradiated onto the sample through the probe. The probe can take a color image, a monochrome image, or a fluorescent image of the sample surface.

The probe includes a collimator 200 attached to one end of the first arm 140 to convert light passing through the first arm 140 into parallel light, a scanner 141 for irradiating light to the target sample, A scan lens 145 for correcting the path of light, and the like.

The reflected sample light travels in the reverse direction through the probe and returns to the coupler 120.

The coupler 120 superimposes the sample light returned via the sample and the reference light reflected on the reference surface 131 and transmits the superimposed reference light to the detector 150. The detector 150 may be a Michelson type interferometer or a Mach-Zender type interferometer.

The detector 150 may include a collimator lens, a diffraction grating, an imaging lens, and a photodetector. The diffraction grating may be either a transmission diffraction grating that transmits light or a reflection diffraction grating that reflects light.

The sample light incident on the detector 150 is collimated by the collimator lens, and is split by the diffraction grating. The spectrally separated light is imaged on the imaging surface of the photodetector by the imaging lens. The photodetector detects each spectrum of the spectroscopically sampled light and couples it into an electrical signal, and outputs the detection signal to the arithmetic and control unit 160. The detection signal is a signal corresponding to the intensity of each spectrum of the spectroscopic sample light. The arithmetic and control unit 160 analyzes the detection signal input from the photodetector of the OCT apparatus 100 to form a fundus tomographic image of the eye to be examined.

In the present invention, an afocal zoom optical system 300 is provided between the collimator 200 and the scanner 141 to adjust the resolution and the DOF according to the target sample. The afocal zoom optical system 300 will be described in detail with reference to Figs. 4A to 4C below.

FIG. 2 is a conceptual diagram of a horizontal resolution and a DOF which change according to F number change of a probe according to an embodiment of the present invention.

FIG. 2A shows the resolution and DOF when the F number is large, and FIG. 2B shows the resolution and DOF when the F number is small. Referring to FIG. 2, as the F number increases, the resolution decreases and the DOF (Z _R ) value increases. On the other hand, as the F number decreases, the resolution increases and the DOF (Z _R ) decreases. The present invention relates to the above two capabilities related to the F-number of the probe of the OCT device 100.

In the conventional OCT apparatus 100, the F number is fixed to a predetermined value when the lens system of the probe is designed and manufactured. Therefore, the F number should be reflected in the design according to the measurement object and the use of the apparatus. Because of this feature, it is limited in usability even though it is expensive equipment. However, in the present invention, it is possible to change the F number of the OCT device 100 by changing the structure of the probe.

3 is a conceptual diagram showing an enlarged one end of the first arm 140 shown in FIG.

Referring to FIG. 3, a probe is mounted at one end of the first arm 140. The probe includes a collimator 200 attached to one end of the first arm 140 to convert light passing through the first arm 140 into parallel light, a scanner 141 for irradiating light to the target sample, A scan lens 145 for correcting the path of light, and the like.

The sample may be an eye to be examined. The sample light incident on the eye to be examined is focused on the fundus and reflected. At this time, the sample light is reflected not only at the fundus surface but also at the deep region of the fundus and scattered at the refractive index boundary. Therefore, the sample light transmitted through the fundus contains information reflecting the surface shape of the fundus, and information reflecting the backscattering state at the refractive index boundary of the deep tissue of the fundus.

The reflected sample light travels in the reverse direction through the probe and returns to the coupler 120.

The scan lens 145 may be formed by combining a plurality of lenses. The light diffused via the scanner 141 passes through the scan lens 145 and is concentrated at a specific position.

4A to 4C are conceptual diagrams showing embodiments of the afocal zoom optical system 300 of the present invention. 4A to 4C, the zoom lens 310 moves along the optical axis and changes the path of the light traveling in the optical system 300. [

According to an embodiment of the present invention, the zoom lens 310 may be connected to the drive motor and may be formed to move along the optical axis by the drive motor.

4A shows an embodiment in which the zoom lens 310 is disposed in the first position. As shown in the figure, the light emitted from the optical fiber collimator has a diameter of? 4 and is incident on the afocal zoom optical system 300. Thereafter, the light having passed through the optical system 300 has a diameter of? 4, reaches the scanner 141, and is irradiated onto the sample through the scan lens 145.

4B shows an embodiment in which the zoom lens 310 is disposed at the second position. As shown in the figure, the light emitted from the optical fiber collimator has a diameter of? 4 and is incident on the afocal zoom optical system 300. Thereafter, the light having passed through the optical system 300 has a diameter of? 3 and reaches the scanner 141.

4C shows an embodiment in which the zoom lens 310 is disposed at the third position. As shown in the figure, the light emitted from the optical fiber collimator has a diameter of? 4 and is incident on the afocal zoom optical system 300. Thereafter, the light having passed through the optical system 300 has a diameter of? 2 and reaches the scanner 141.

As described above, the F number F / # of the probe is changed by the movement of the zoom lens 310. [ In the present embodiment, the F number is increasing as the zoom lens 310 is moved to the right. However, the shape of the zoom lens 310 may be changed so that the F number is reduced as it moves to the right.

4A to 4C, the afocal zoom optical system 300 includes a zoom lens 310, a first lens 320, a second lens 330, and a third lens 340.

The zoom lens 310 is formed to be movable along the optical axis as described above. The movement may be manually operated or automatically operated by a drive motor. The front and back surfaces of the zoom lens 310 may be formed to form different types of lenses. For example, the front surface may be formed of a convex lens and the rear surface may be formed of a concave lens. According to another embodiment, the front surface may be formed of a convex lens or a concave lens, and the rear surface may be formed in a plane. The shapes of the front and rear surfaces of the zoom lens 310 are changed corresponding to the combination of the first to third lenses 340. [

According to an embodiment of the present invention, the front surface of the first lens 320 is formed into a convex lens shape. The collimated light irradiated through the optical fiber collimator passes through the first lens 320 and converges toward the optical axis. The light passing through the first lens 320 can be gathered or diverged through the zoom lens 310. The front surface of the zoom lens 310 is formed to have a concave lens shape so that light passing through the zoom lens 310 is diverged and incident on the second lens 330. However, according to another embodiment, the front surface of the zoom lens 310 may be formed of a convex lens so that light may be gathered toward the optical axis.

According to an embodiment of the present invention, the second lens 330 and the third lens 340 are formed as one set. In other words, if the second lens 330 collects light toward the optical axis, the third lens 340 emits light so that the emitted light forms a parallel light. Likewise, if the second lens 330 emits light, the third lens 340 collects the light so that the emitted light forms parallel light. The second lens 330 and the third lens 340 are overlapped with each other to perform the above function and when the second lens 330 is a convex lens, the third lens 340 is a concave lens, And the third lens 340 is a convex lens when the third lens 330 is a concave lens.

The OCT apparatus 100 configured as described above includes a probe capable of changing the F number of the optical system 300 to change the focal position of the optical system 300 formed on the probe or lower the image signal- So that the resolution and DOF (depth of focus) can be adjusted appropriately. This makes it possible to improve the image output through the apparatus and to expand the application range of the apparatus.

The OCT apparatus 100 described above is not limited to the configurations and the methods of the embodiments described above, but the embodiments may be configured such that all or some of the embodiments are selectively combined so that various modifications can be made .

Claims (10)

A probe for an OCT device, which is mounted on one end of an OCT device,
And an afocal zoom optical system configured to change an F number of the probe without changing a focus position of the probe. The method according to claim 1,
A scan lens for correcting a path of light irradiated to the sample facing the sample;
An optical fiber collimator disposed adjacent to the scan lens to irradiate parallel light to the scan lens; And
And an afocal zoom optical system disposed between the scan lens and the optical fiber collimator for varying the F number of the probe. 3. The method of claim 2,
The focal zoom optical system includes:
Wherein the diameter of the light irradiated to the scan lens is changed to vary the F number. The method of claim 3,
The focal zoom optical system includes:
And a zoom lens that moves along an optical axis so as to collect or diverge the light. 5. The method of claim 4,
The focal zoom optical system includes:
And a driving motor connected to the zoom lens to move the zoom lens. 5. The method of claim 4,
The focal zoom optical system includes:
A first lens for collecting light emitted from the optical fiber collimator toward an optical axis;
A second lens that collects light traveling through the first lens toward the optical axis; And
And a third lens that overlaps the second lens and emits light so that the light refracted by the second lens is irradiated to the scan lens in the form of parallel light,
Wherein the zoom lens moves along the optical axis between the first lens and the second lens to change a diameter of light incident on the second lens. A light source for generating light;
A coupler for branching the light generated from the light source to proceed to the first arm and the second arm; And
And a probe formed on one end of the first arm and irradiating light to the sample,
Wherein the probe comprises:
A scan lens for correcting a path of light irradiated to the sample facing the sample;
An optical fiber collimator formed at one end of the first arm to irradiate parallel light to the scan lens; And
And an apical zoom optical system disposed between the scan lens and the optical fiber collimator for varying the F number of the probe. 8. The method of claim 7,
The first arm irradiates the branched light to a sample and then transmits the light reflected from the sample to a detector,
Wherein the second arm reflects the branched light onto the reference surface so as to be combined with the light reflected on the sample, and then transmits the reflected light to the detector. 9. The method of claim 8,
The focal zoom optical system includes:
And a zoom lens that moves along an optical axis so as to collect or diverge light. 10. The method of claim 9,
The focal zoom optical system includes:
A first lens for collecting light emitted from the optical fiber collimator toward an optical axis;
A second lens that collects light traveling through the first lens toward the optical axis; And
And a third lens that overlaps the second lens and emits light so that the light refracted by the second lens is irradiated to the scan lens in the form of parallel light,
Wherein the zoom lens moves along the optical axis between the first lens and the second lens to change the diameter of light incident on the second lens.

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