KR20080026338A - Optical source of optical coherence tomography - Google Patents

Abstract

An optical source of an optical coherence tomography is provided to improve depth direction resolution in the optical coherence tomography by widening a wavelength variable region and a full width half maximum and have a rapid image obtaining speed through a rapid wavelength conversion speed by using a galvanometer. A semiconductor optical amplifier(300) generates broadband light. A polarizing controller(310) controls polarization of the light by receiving the broadband light from the semiconductor optical amplifier. A single mode optical fiber distributor(320) distributes a ratio of light amount in a diffraction grating direction and an output stage direction by receiving the polarization-controlled light from the polarizing controller. A first optical fiber-collimator(330) impinges the light distributed by the single mode optical fiber distributor as uniform parallel light to a diffraction grating. The diffraction grating(340) diffracts the light impinged from the first optical fiber-collimator. A galvanometer coupled mirror(350) reflects first diffraction light, impinged by being diffracted from the diffraction grating, to the diffraction grating. A second optical fiber-collimator(360) impinges the light distributed by the single mode optical fiber distributor to the output stage as uniform-size parallel light. Optical fibers(370) are passages to transmit the light by being positioned between broadband wavelength conversion light source devices.

Description

Optical wavelength of optical coherence tomography

1 is a block diagram showing a schematic configuration of a conventional optical coherence tomography apparatus.

FIG. 2 is an explanatory diagram for explaining the operation of the light source unit 110 and the light reflection unit 130 in FIG. 1 in more detail.

3 is an explanatory diagram showing a brief configuration of a broadband wavelength conversion light source for an optical coherence tomography apparatus according to a preferred embodiment of the present invention.

4 is a graph showing the relationship between the wavelength of the broadband wavelength conversion light source for optical coherence tomography according to an embodiment of the present invention and the dBm (dBm)

5 is a graph showing a relationship between time and light intensity of a broadband wavelength conversion light source for an optical coherence tomography apparatus according to an exemplary embodiment of the present invention.

<Description of Major Symbols in Drawing>

110: light source unit 120: measuring unit

130: light reflection unit 140: detection unit

150: preprocessing amplifier 160: filter

170: demodulator 180: A / D converter

190: image display unit 200: diode laser

210: collimator 230,340: diffraction grating

240: PZT coupling mirror 300: semiconductor optical amplifier

310: polarization controller 320: single mode fiber splitter

330: first optical fiber-collimator 350: galvanometer combined mirror

360: second optical fiber-collimator 370: optical fiber

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wideband wavelength converting light source for use in an optical coherence tomography, and more particularly, to a tunable light source having a fast broadband wavelength converting.

Optical Coherence Tomography (OPT) is a device that captures live tissues or cells in high resolution in real time, and allows the non-contact and non-invasive observation of the inside of a living body using a light source, as well as the difference between soft tissues. Can be classified to obtain a more precise image.

1 is a block diagram showing a general configuration of a conventional optical coherence tomography apparatus, which includes a light source unit 110, a measurement unit 120, a light reflection unit 130, a detection unit 140, a preprocessing amplifier 150, and a filter. The unit 160 includes a demodulator 1700, an A / D converter 180, and an image display unit 190.

The light source unit 110 enters light into the measuring unit 120 and the light reflecting unit 130, receives and amplifies light of a specific wavelength sent from the light reflecting unit 130, and then outputs the light to the measuring unit 120. .

The measuring unit 120 provides light to a portion to be monitored through a focusing lens as a measuring portion to obtain a desired image. When the provided light is reflected back to the measurement part, the light is incident to the detector 140.

The light reflection unit 130 reflects the light received by the periodically moving mirror to incident light of a specific wavelength reflected by the light source unit 110. At this time, only light having a specific wavelength is incident to the light source unit 110 by the movement of the mirror, and the remaining light is sent to the detector 140.

The detector 140 detects the interference signal received from the measurement unit 120 and changes according to the time received from the light reflection unit 130 and transmits the interference signal to the preprocessing amplifier 150.

The preprocessing amplifier 150 amplifies the interference signal received from the detector 140 and transmits the amplified signal to the filter unit 160.

The filter unit 160 receives the signal amplified by the preprocessing amplifier 150 and transmits only the signal of the required region to the demodulator 170.

The demodulator 170 demodulates the signal received from the filter unit 160 and transmits the demodulated signal to the A / D converter 180.

The A / D converter 180 converts the analog signal received from the demodulator 170 into a digital signal and transmits the analog signal to the image display unit 190.

The image display unit 190 displays an image of a portion to be measured, and the optical coherence tomography apparatus may display living tissue or cells in real time.

FIG. 2 is an explanatory diagram for describing the operation of the light source unit 110 and the light reflection unit 130 in FIG. 1 in more detail. The diode laser 200, the collimator 210, the diffraction grating 230, It consists of a PZT coupling mirror 240.

The diode laser 200 is a diode that generates a laser by using a forward semiconductor junction, and serves as the light source unit 110. Light from the diode laser 200 is incident on the collimator 210. In addition, the light is reflected by the PZT coupling mirror 240 and incident on the diffraction grating 200 to receive and amplify the light of the specific wavelength reflected by the diffraction grating 200 and then enter the measuring unit 120.

The collimator 210 injects the diffused light emitted from the diode laser 200 and the diode laser 200 into the diffraction grating 230 in parallel.

The diffraction grating 230 is for obtaining a spectrum of light by using diffraction and interference, which is like arranging a few thin slits. The diffracted light comes out. The diffraction grating 230 diffracts the parallel light incident by the collimator 210.

Piezo electric (PZT) coupling mirror 240 receives the first diffracted light of the light diffracted in the diffraction grating 230 and reflects again. The first diffracted light diffracted in the diffraction grating 230, that is, light of a specific wavelength incident perpendicularly to the plane of the PZT coupling mirror 240 is reflected by the diffraction grating 200, and the diffraction grating 200 is then returned to the specific wavelength. Reflect light and enter the diode laser 200.

When the above process is repeated several times, light of a specific wavelength is amplified by the diode laser 200, and the light of the amplified specific wavelength is incident to the measurement unit 120, which is the source end. After the light having a specific wavelength is incident on the measuring unit 120, the light excluding the reflected light and the light reflected by the light reflecting unit 130 and incident on the diode laser 200 is sent to the detector 140 to be measured. Image information on the part is detected. The wavelength output to the measurement unit 120 by the specific wavelength is varied by the angle of the piezo electric (PZT), the selection of the wavelength is determined by the equation (1).

As described above, in the conventional optical coherence tomography camera, when the angle between the diode laser 200 and the diffraction grating 230 changes even a little, there is a disadvantage in that all optical components of the optical coherence tomography container must be rearranged. In addition, since the diode laser 200 and the PZT are used, the wavelength variable region of the wavelength conversion light source is 40 nm or less, and the FWHM (FWHM: Full Width Half Maximum) is also narrow to 20 nm or less, and the conversion speed is slow.

Accordingly, there is a need for a broadband wavelength conversion light source for an optical coherence tomography container having a constant output of light regardless of an incident angle of light incident on a diffraction grating and having a wide wavelength variable region and a high conversion speed.

Accordingly, the present invention provides a wideband wavelength conversion light source for an optical coherence tomography apparatus which can obtain a constant light output regardless of the incident angle of light incident on the diffraction grating, and has a wide wavelength variable region and a high conversion speed.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a broadband wavelength conversion light source for an optical coherence tomography apparatus, which can obtain a constant light output regardless of an incident angle of light incident on a diffraction grating.

Another object of the present invention is to provide a broadband wavelength conversion light source for an optical coherence tomography camera having a wide wavelength variable region and a high conversion speed.

Hereinafter, the configuration and operation of a broadband wavelength conversion light source for an optical coherence tomography apparatus according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is an explanatory diagram showing a brief configuration of a broadband wavelength conversion light source for an optical coherence tomography apparatus according to an exemplary embodiment of the present invention, wherein a semiconductor optical amplifier 300, a polarization controller 310, and a single mode optical fiber splitter 320 are shown. , The first optical fiber collimator 330, the diffraction grating 340, the galvanometer coupling mirror 350, the second optical fiber collimator 360, and the optical fiber 370.

The semiconductor optical amplifier (SOA) 300 is an optical amplifier using a gain mechanism in the semiconductor active layer, such as a semiconductor laser, and the broadband light emitted from the semiconductor optical amplifier 300 is optically transmitted to the polarization controller 310. 370. The light of a specific wavelength reflected by the galvanometer coupling mirror 350 and reflected by the diffraction grating 340 is received and amplified and sent to the measuring unit which is an output terminal. The semiconductor optical amplifier 300 uses one having an AR / HR coating so that light travels only in the other direction.

The polarization controller 310 receives the broadband light from the semiconductor optical amplifier 300 through the optical fiber 370, and adjusts the polarization of the light to be transmitted to the single mode optical fiber distributor 320 through the optical fiber 370.

The single mode optical fiber splitter 320 adjusts the ratio of the amount of light distributed in the direction of the diffraction grating and the output stage to amplify the polarized light emitted from the polarization controller 310 with maximum efficiency. 5% in the direction of the output terminal, 95% in the direction of the diffraction grating 340 is sent to send. This is to properly adjust the ratio of the light intensity traveling toward the diffraction grating 340 and the light intensity traveling toward the output terminal. By using a single-mode fiber splitter, a constant light output can be obtained regardless of the incident angle of light entering the diffraction grating.

The first optical fiber collimator 330 enters the light distributed from the single mode optical fiber splitter 320 into the diffraction grating 340 and enters parallel light of a predetermined size out of the optical fiber. In addition, the light of the specific wavelength reflected by the galvanometer coupling mirror 350 and reflected back from the diffraction grating 340 is sent to the semiconductor optical amplifier 300.

The diffraction grating 340 receives parallel light of a predetermined magnitude incident from the first optical fiber collimator 330 and diffracts the light. Among them, the first diffracted light is reflected by the galvanometer coupling mirror 350 and is reflected by the diffraction grating 340 once again to be incident to the first optical fiber-collimator 330 to move toward the semiconductor optical amplifier 300. The reflected light at this time is light of a certain wavelength range. In order to increase efficiency, the diffraction grating 340 uses a plated with gold.

The galvanometer coupling mirror 350 is a mirror coupled with the galvanometer, and the first diffracted light diffracted by the diffraction grating 340 is incident on the plane of the galvanometer coupling mirror 350 and then the diffraction grating 340. ) And the light reflected from the diffraction grating 340 enters the first fiber-collimator 330.

The second optical fiber collimator 360 serves to inject light distributed from the single mode optical fiber splitter 320 into a specific wavelength in parallel to the measurement unit, that is, the output terminal.

The optical fiber 370 is positioned between the broadband wavelength converting light source devices to serve as a path for transmitting light.

As described above, the operation of the broadband wavelength conversion light source for the optical coherence tomography apparatus of the present invention will be described briefly. The single-mode optical fiber splitter 320 receives the broadband light from the semiconductor optical amplifier 300 in the direction and output stage of the diffraction grating. It proceeds to, the parallel light of a certain size by the first optical fiber-collimator 330 exits the optical fiber and is incident to the diffraction grating 340. The light incident on the diffraction grating 340 is diffracted, of which the first diffracted light is incident perpendicularly to the galvanometer coupling mirror 350 and is incident on the diffraction grating 340 by the galvanometer coupling mirror 350. Light incident on the diffraction grating 340 is reflected again, and light having a specific wavelength is incident on the first optical fiber collimator 330 and transmitted to the semiconductor optical amplifier 300. The light of a specific wavelength transmitted to the semiconductor optical amplifier 300 is amplified and polarized light is controlled by the polarization controller 320 and then sent to the second optical fiber collimator 360 through the single mode optical fiber distributor 320 to be measured. Incident on the part. The wavelength output to the output terminal is determined by the angle of the galvanometer, and to become a wavelength conversion light source, the galvanometer is changed at a predetermined angle and a constant speed.

Figure 4 is a graph showing the relationship between the wavelength of the broadband wavelength conversion light source for the optical coherence tomography light source according to an embodiment of the present invention and the dB (dBm), Figure 4 (a) is a galvanometer arbitrary When stopped at an angle, only a certain wavelength is amplified. That is, in (a) it can be seen that only a wavelength of about 840nm amplified. It can be seen that the light of the desired wavelength can be amplified by controlling the angle of the galvanometer. FIG. 4 (b) shows that a specific wavelength band is amplified by the movement of the galvanometer when the galvanometer is driven. It shows that the wavelength variable region is about 70 nm and the fouling width is about 40 nm.

5 is a graph showing the relationship between the time and the light intensity of the broadband wavelength conversion light source for optical coherence tomography according to an embodiment of the present invention, the light intensity at a specific wavelength according to the time the galvanometer moves It shows that the wavelength variable is changing rapidly. Therefore, it can be seen that the broadband wavelength converting light source for the optical coherence tomography apparatus of the present invention has a wide wavelength variable region and a fast variable speed.

The present invention is not limited to the above described and illustrated in the drawings, and of course, more modifications and variations are possible to those skilled in the art within the scope of the following claims.

As described above, the broadband wavelength converting light source for the optical coherence tomography apparatus of the present invention uses a semiconductor optical amplifier and a single mode optical fiber splitter so that the light emitted in the direction of the diffraction grating and the incident angle of the light incident on the diffraction grating are constant You can get the light output. In addition, the use of a galvanometer instead of PZT increases the depth resolution in the optical coherence tomography because of the wide wavelength range and fouling width, and has a fast image acquisition speed due to the fast wavelength conversion speed.

Claims (8)

A semiconductor optical amplifier for generating broadband light; A polarization controller for controlling the polarization of light by receiving broadband light from the semiconductor optical amplifier; A single mode optical fiber splitter which receives the polarized light from the polarization controller and distributes the ratio of light in the direction of the diffraction grating and the output end; A first optical fiber collimator for injecting light distributed from the single mode optical fiber splitter into a parallel light having a predetermined size with a diffraction grating; A diffraction grating diffracting light incident from the first optical fiber collimator; A galvanometer coupling mirror in which the first diffracted light diffracted from the diffraction grating is incident to reflect the light into the diffraction grating; A second optical fiber collimator for injecting the light distributed by the single mode optical fiber splitter into a predetermined size in parallel; Broadband wavelength conversion light source for optical coherence tomography comprising a; optical fiber which is a passage for transmitting light located between the broadband wavelength conversion light source devices. The method of claim 1, Broadband wavelength conversion light source for optical coherence tomography comprising a semiconductor optical amplifier, characterized in that the amplified by the light reflected from the galvanometer mirror and reflected back from the diffraction grating. The method of claim 1, wherein A broadband wavelength converting light source for an optical coherence tomography camera comprising a semiconductor optical amplifier, wherein one side is AR / HR coated. The method of claim 1, A broadband wavelength conversion light source for an optical coherence tomography apparatus comprising a single mode optical fiber splitter for distributing 5% light toward the first optical fiber-collimator and 90% toward the second optical fiber-collimator. The method of claim 1, And a first optical fiber-collimator for receiving light of a specific wavelength reflected from the galvanometer coupling mirror and reflected back from the diffraction grating toward the semiconductor optical amplifier. The method of claim 1, Broadband wavelength conversion light source for optical interference tomography comprising a diffraction grating, characterized in that for reflecting the light reflected from the galvanometer coupling mirror to the first optical fiber-collimator. The method of claim 1, wherein A broadband wavelength conversion light source for an optical coherence tomography device, comprising a diffraction grating, plated with gold. A broadband wavelength conversion light source for an optical coherence tomography, wherein the wavelength variable region is about 70 nm and a full width half maximum (FWHM) is about 40 nm.

Images