CN117369062A - Multi-light source high-resolution optical imaging device and method based on optical switch - Google Patents

Abstract

The invention provides a multi-light source high-resolution optical imaging device and method based on an optical switch. The optical switch is used to connect super-radiant light-emitting diodes with two bandwidth ranges and an optical fiber coupler. At the same detection position of the measured target, The host computer realizes interference signal measurement in two bandwidth ranges by controlling the state of the optical switch and the collection of the spectrometer. By synthesizing the two interference signals on the software, the bandwidth range of the light source is expanded, thereby improving the depth resolution of the system and achieving optical non-contact, damage-free ultra-high-precision three-dimensional optical imaging.

Description

Multi-light source high-resolution optical imaging device and method based on optical switch

Technical field

The invention belongs to the technical field of non-contact optical coherent imaging, and specifically relates to a multi-light source high-resolution optical imaging device and method based on optical switches.

Background technique

Optical Coherence Tomography (OCT) is an internal structure imaging technology that integrates the advantages of non-contact, non-destructive, micron-level high resolution, and high-speed real-time imaging. Internal structure imaging technology refers to technology that penetrates the surface of an object, detects the internal structure of the target, and reconstructs and displays the image. During the detection process, the media carrier plays the role of penetrating the surface of the object and carrying information about the structure of the object. The depth resolution of the OCT system is related to the central wavelength and bandwidth of the light source. The shorter the central wavelength of the light source and the wider the bandwidth, the higher the depth resolution of the system. However, due to limitations in manufacturing technology, the bandwidth of superluminescent diodes is difficult to widen indefinitely, resulting in limited depth resolution of the OCT system.

Contents of the invention

In view of this, in view of the defects and shortcomings of the existing technology, the main purpose of the present invention is to provide a multi-light source high-resolution optical imaging device and method based on optical switches, breaking through the limitation of the light source bandwidth on the depth resolution of the OCT system, and greatly improving the depth resolution of the OCT system. Improve the depth resolution of the system and achieve ultra-high-precision three-dimensional imaging.

The technical solutions specifically adopted by the present invention to solve the technical problems are:

A multi-light source high-resolution optical imaging device based on an optical switch, which is characterized in that: an optical switch is used to connect superradiant light-emitting diodes with two bandwidth ranges and an optical fiber coupler. At the same detection position of the measured target, the upper position The machine realizes interference signal measurement in two bandwidth ranges by controlling the state of the optical switch and the collection of the spectrometer.

Further, it includes two superluminescent diodes with different bandwidth ranges, an optical switch, a 2×2 single-mode optical fiber coupler, a reference arm, a detection arm, a detection arm frame, a spectrometer and a system control device. PC with data collection;

The two super-radiant light-emitting diodes radiate broadband light sources with different bandwidths into the optical switch; the optical switch is controlled by a TTL signal to select the super-radiant light-emitting diode and connect it to a 2×2 optical fiber coupler, and the 2×2 optical fiber coupler converts the incident broadband light According to the splitting ratio of the coupler, it is divided into reference light and detection light; the reference light is collimated into parallel light by the collimating lens in the reference arm and focused by the convex lens to the reflector, which reflects the original path of the reference light back to the fiber coupler; detection The light is collimated by the collimating lens into parallel light and focused by the focusing objective lens to the target being measured. Different structural layers of the measured target will reflect or backscatter the detection light back into the fiber coupler; reflection or backscatter from different structural layers of the measured target or The backscattered detection light and the reference light reflected from the mirror meet at the fiber coupler and form interference; the interference signal enters the spectrometer and is collimated into parallel light by the collimating mirror in the spectrometer and then illuminated. In the transmission grating, the light beam is expanded by the grating according to the wavelength and then focused to the CMOS camera and transmitted to the host computer through the GIGE communication protocol.

Furthermore, the reference arm is a length-adjustable reference arm for adjusting the optical path difference between the reference light and the detection light.

Furthermore, it also includes an XY displacement stage for controlling the movement of the tested sample to achieve high-precision three-dimensional scanning.

Further, the optical switch is used to receive the TTL trigger signal sent by the host computer and control the on and off of the two light sources and the optical fiber coupler.

Further, the imaging method includes the following steps:

Step S1: Two super-radiant light-emitting diodes with different bandwidths radiate broadband light sources into the optical switch. The host computer sends out a TTL square wave signal to control the optical switch and a pulse signal to control the spectrometer. The optical switch makes the super-radiant light-emitting diodes and the fiber coupler respectively Complete a connection;

Step S2: The connected light source enters the fiber coupler and is divided into reference light and detection light. The detection light carries the layered structure information of the sample under test and the reference light to form a multi-frequency interference signal and enters the spectrometer;

Step S3: The spectrometer starts collecting after receiving the pulse signal, and collects the interference signals detected by the two superradiant light-emitting diodes respectively;

Step S4: Combine the two collected interference signals, convert them to the wavenumber domain and perform Fourier transform to obtain the depth structure information of the sample;

Step S5: Control the XY linear displacement stage to drive the measured sample to move to the next measured point, and loop through steps S1-S4 to complete the three-dimensional information collection and imaging of the measured sample.

Further, in step S3, the multi-frequency interference signal collected by the spectrometer using the first superradiant light-emitting diode as the detection source is as follows:

Among them, the first term is the DC term, the second term is the autocoherence term, and the third term is the interference signal term, which modulates the internal structure information of the measured sample into the frequency of the interference signal; S _r (λ) is the reference light _The spectral _power distribution function _of Or the optical path difference between the detection light and the reference light that is backscattered; 2d _nm represents the optical path difference of the detection light that is reflected or backscattered from the nth and mth layers of the sample; Re represents the complex domain interference signal real part.

The multi-frequency interference signal collected by the spectrometer when using the second superluminescent diode as the detection source is as follows:

Among them, λ ₁ ＜ λ ₃ ＜ λ ₂ ＜ λ ₄ .

Further, in step S4, the multi-frequency interference signals of formula (1) and formula (2) are synthesized into the following signals, specifically:

Among them, S _r '(λ) is the spectral power distribution function of the reference light after synthesis; S' _n (λ) and S' _m (λ) are the detection spectral power distribution returned by reflection or backscattering from different sample layers after synthesis. function.

Convert equation (3) to the wave number domain, specifically:

Among them, k is the wave number, and its relationship with wavelength is

Further, in step S4, the internal structure information of the measured sample can be obtained by performing fast Fourier transform on the interference signal of equation (4), specifically as follows:

Among them, δ is the Yurac function.

Compared with the existing technology, the present invention and its preferred solution use optical switches to connect superluminescent diodes with two bandwidth ranges and optical fiber couplers. At the same detection position of the measured target, the host computer controls the optical switch. The acquisition of state and spectrometer realizes the measurement of interference signals in two bandwidth ranges. By synthesizing the two interference signals on the software, the bandwidth range of the light source is expanded, thereby improving the depth resolution of the system and achieving optical non-contact, damage-free ultra-high-precision three-dimensional optical imaging.

Description of the drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments:

Figure 1 is a system structure diagram of an embodiment of the present invention, in which 1 and 2 are superradiant light-emitting diodes with two bandwidth ranges, 3 is an optical switch, 4 is a 2×2 single-mode optical fiber coupler, 5 is a reference arm, and 6 is the collimating lens, 7 is the focusing lens, 8 is the reflecting mirror, 9 is the detection arm, 10 is the collimating lens, 11 is the focusing objective lens, 12 is the detection arm frame, 13 is the XY displacement stage, and 14 is the measured sample ( Including: biological samples, composite materials and optical components, etc.), 15 is the fiber collimator, 16 is the transmission grating, 17 is the focusing lens, 18 is the CMOS camera, 19 is the spectrometer, and 20 is the host computer.

Figure 2 shows the signal collected by the spectrometer according to the embodiment of the present invention.

Figure 3 is a signal processing process diagram of the embodiment of the present invention.

FIG. 4 is a comparison diagram of imaging resolution between the single-bandwidth light source system and this system according to the embodiment of the present invention.

Detailed ways

In order to make the features and advantages of this patent more obvious and easy to understand, examples are given below and explained in detail as follows:

It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used in this specification have the same meanings commonly understood by one of ordinary skill in the art to which this application belongs.

It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular forms are also intended to include the plural forms unless the context clearly indicates otherwise. Furthermore, it will be understood that when the terms "comprises" and/or "includes" are used in this specification, they indicate There are features, steps, operations, means, components and/or combinations thereof.

As shown in Figures 1 to 4, an embodiment of the present invention provides a multi-light source high-resolution optical imaging device based on an optical switch. A sample is provided, including superradiant light-emitting diodes 1 and 2 in two bandwidth ranges, and an optical switch 3 , single-mode fiber coupler 4, reference arm 5, collimating lens 6, focusing lens 7, reflecting mirror 8, detection arm 9, collimating lens 10, focusing objective lens 11, detection arm frame 12, XY displacement stage 13, by Test samples 14 (including biological samples, composite materials and optical components, etc.), fiber collimator 15, transmission grating 16, focusing lens 17, CMOS camera 18, spectrometer 19, host computer 20.

Among them, two super-radiant light-emitting diodes 1 and 2 radiate broadband light sources with different bandwidths into the optical switch 3; the optical switch 3 is controlled by the TTL signal sent by the host computer 20 and then selects the super-radiant light-emitting diode to be connected to the optical fiber coupler 4. The optical fiber coupler 4 divides the incident broadband light into reference light and detection light according to the coupler splitting ratio; the reference light is collimated into parallel light by the collimating lens 6 in the reference arm 5 and focused by the convex lens 7 onto the reflector 8 and reflected The mirror 8 reflects the original path of the reference light back to the optical fiber coupler 4; the detection light is collimated by the collimating lens 10 into parallel light and focused by the focusing objective lens 11 to the measured target 14 (including biological samples, composite materials and optical elements, etc. ), the different structural layers of the measured target 14 will reflect or backscatter the detection light back into the optical fiber coupler 4; the detection light reflected or backscattered from the different structural layers of the measured target 14 is different from the detection light reflected from the mirror. The reference light returned meets and interferes at the fiber coupler 4; the interference signal enters the spectrometer 19, is collimated into parallel light by the fiber collimator 15 in the spectrometer 19, and then irradiates into the transmission grating 16, and the light beam is 16 is expanded according to wavelength and then focused to the CMOS camera 18 and transmitted to the host computer 20 through the GIGE communication protocol.

In this example, the length of the reference arm 5 is adjustable to adjust the optical path difference between the reference light and the detection light.

In this example, the XY displacement stage is used to control the movement of the measured target to achieve high-precision three-dimensional scanning.

In this example, the optical switch is used to receive the TTL trigger signal sent by the host computer and control the on and off of the two light sources and the fiber coupler.

Preferably, the device can be used for the detection of biological samples, composite materials, optical components and other samples.

Preferably, in this embodiment, a multi-light source high-resolution optical imaging method based on optical switches is also provided, including the following steps:

Step S1: Two super-radiant light-emitting diodes with different bandwidths radiate broadband light sources into the optical switch. The host computer sends out a TTL square wave signal to control the optical switch and a pulse signal to control the spectrometer. The optical switch makes the super-radiant light-emitting diodes and the fiber coupler respectively Complete a connection;

Step S2: The connected light source enters the fiber coupler and is divided into reference light and detection light. The detection light carries the layered structure information of the sample under test and the reference light to form a multi-frequency interference signal and enters the spectrometer;

Step S3: The spectrometer starts collecting after receiving the pulse signal, and collects the interference signals detected by the superradiant light-emitting diodes 1 and 2 respectively;

Step S4: Combine the two collected interference signals, convert them to the wave number domain and perform Fourier transform to obtain the depth structure information of the sample;

Step S5: Control the XY linear displacement stage to drive the measured sample to move to the next measured point, and loop through steps S1-S4 to complete the three-dimensional information collection and imaging of the measured sample.

This patent is not limited to the above-mentioned best embodiments. Under the inspiration of this patent, anyone can come up with various other forms of optical switch-based multi-light source high-resolution optical imaging devices and methods. Anyone who applies for a patent according to this invention All changes and modifications made equally shall fall within the scope of this patent.

Claims (9)

1. An optical switch-based multi-light source high-resolution optical imaging device is characterized in that: the superradiation light emitting diode with two bandwidth ranges is connected with the optical fiber coupler by utilizing the optical switch, and the upper computer realizes interference signal measurement with two bandwidth ranges by controlling the state of the optical switch and the acquisition of the spectrometer at the same detection position of the detected target.

2. The optical switch-based multi-light source high resolution optical imaging apparatus of claim 1, wherein: the system comprises two super-radiation light emitting diodes with different bandwidth ranges, an optical switch, a 2X 2 single-mode optical fiber coupler, a reference arm, a detection arm bracket, a spectrometer and an upper computer for system control and data acquisition;

the two super-radiation light-emitting diodes radiate broadband light sources with different bandwidths into an optical switch; the optical switch is connected with a 2X 2 optical fiber coupler through a TTL signal control selection superradiation light emitting diode, and the 2X 2 optical fiber coupler divides incident broadband light into reference light and detection light according to the splitting ratio of the coupler; the reference light is collimated into parallel light by a collimating lens in the reference arm and focused to a reflecting mirror by a convex lens, and the reflecting mirror reflects the reference light in a primary way back to the optical fiber coupler; the detection light is collimated into parallel light by a collimating lens and focused to a detected target by a focusing objective lens, and different structural layers of the detected target reflect or back scatter the detection light back to the optical fiber coupler; the detection light reflected or back scattered from different structural layers of the detected target meets the reference light reflected from the reflecting mirror and forms interference at the optical fiber coupler; the interference signal enters the spectrometer, is collimated into parallel light by a collimating mirror in the spectrometer and irradiates into a transmission type grating, and the light beam is unfolded by the grating according to the wavelength, focused to a CMOS camera and transmitted to an upper computer through a GIGE communication protocol.

3. The optical switch-based multi-light source high resolution optical imaging apparatus of claim 2, wherein: the reference arm is a length-adjustable reference arm and is used for adjusting the optical path difference of the reference light and the detection light.

4. The optical switch-based multi-light source high resolution optical imaging apparatus of claim 2, wherein: the device also comprises an XY displacement table for controlling the movement of the tested sample so as to realize high-precision three-dimensional scanning.

5. The optical switch-based multi-light source high resolution optical imaging apparatus of claim 2, wherein: the optical switch is used for receiving TTL trigger signals sent by the upper computer and controlling the on-off of the two light sources and the optical fiber coupler.

6. The optical switch-based multi-light source high resolution optical imaging apparatus of claim 2, wherein:

the imaging method comprises the following steps:

step S1: the super-radiation light-emitting diodes with different bandwidths radiate a broadband light source to enter the optical switch, the upper computer sends TTL square wave signals to control the optical switch and a pulse signal to control the spectrometer, and the optical switch enables the super-radiation light-emitting diode and the optical fiber coupler to be communicated once respectively;

step S2: the communicated light source is divided into reference light and detection light after entering the optical fiber coupler, and the detection light forms a multi-frequency interference signal with the reference light by carrying layered structure information of a sample to be detected and enters the spectrometer;

step S3: the spectrometer starts to collect after receiving the pulse signals, and interference signals detected by the two super-radiation light-emitting diodes at a time are collected;

step S4: synthesizing the two collected interference signals, converting the two interference signals into a wave number domain, and carrying out Fourier transformation to obtain depth structure information of a sample;

step S5: and controlling the XY linear displacement platform to drive the tested sample to move to the next tested point, and circularly performing steps S1-S4 to complete three-dimensional information acquisition and imaging of the tested sample.

7. The imaging method of the optical switch-based multi-light source high resolution optical imaging apparatus according to claim 6, wherein:

in step S3, the multi-frequency interference signal acquired by the spectrometer when the first superluminescent diode is used as the detection source is as follows:

wherein, the 1 st item is a direct current item, the 2 nd item is an auto-coherent item, and the 3 rd item is an interference signal item, which modulates the internal structure information of the tested sample into the frequency of the interference signal; s is S _r (lambda) is the spectral power distribution function of the reference light; s is S _n (λ)、S _m (lambda) is the detected spectral power distribution function of the back reflection or back scattering of the different sample layers; lambda is the wavelength of light; 2d _n Indicating reflection or back-scattering from the nth layer of the sampleOptical path difference between the detection light and the reference light; 2d _nm Indicating the optical path difference of the probe light reflected or back-scattered from the nth and mth layers of the sample; re represents the real part of the complex domain interference signal.

The multi-frequency interference signals acquired by the spectrometer by taking the second super-radiation light-emitting diode as a detection source are as follows:

wherein lambda is ₁ ＜λ ₃ ＜λ ₂ ＜λ ₄ 。

8. The imaging method of the optical switch-based multi-light source high resolution optical imaging apparatus according to claim 6, wherein:

in step S4, the multi-frequency interference signals of the formula (1) and the formula (2) are synthesized as follows:

wherein S is _r 'lambda' is the spectral power distribution function of the synthesized reference light; s'. _n (λ)、S' _m (lambda) is the detected spectral power distribution function of the back reflection or back scattering of the different sample layers after synthesis.

Converting formula (3) into the wavenumber domain, specifically:

wherein k is the wavenumber and its relation to the wavelength is

9. The imaging method of the optical switch-based multi-light source high resolution optical imaging apparatus according to claim 6, wherein:

in step S4, the interference signal of formula (4) is subjected to fast fourier transform to obtain internal structure information of the sample to be measured, specifically:

where δ is the especially Rake function.