Swept laser source system with signal shaping

Abstract

The present application discloses a signal shaping swept laser source system, which includes a fiber Fabry-Perot tunable filter, a beam wavelength controller, a first isolator, a laser beam amplifier, a signal shaper, a beam splitter and a second isolator. The fiber Fabry-Perot tunable filter receives a voltage signal to filter a received wide spectrum beam and output a specific wavelength beam. The beam wavelength controller outputs the voltage signal to the fiber Fabry-Perot tunable filter according to a preset parameter. The laser beam amplifier is used to initially emit the wide spectrum beam, and continuously amplify the specific wavelength beam until it becomes the main beam. The signal shaper is used to perform half-cycle filtering on the wide spectrum beam and the specific wavelength beam according to waveform shaping parameters, wherein the waveform shaping parameters have different gain values.

Description

TECHNICAL FIELD

[0001] The present application relates to a swept laser, in particular to a swept laser light source system with signal shaping capable of adjusting and optimizing the authenticity of three-dimensional information of an object to be observed. BACKGROUND

[0002] Optical coherence tomography (OCT) is also known as optical coherence tomography, optical coherence tomography, which is an imaging technology for obtaining and processing optical signals. It uses low coherence light (such as near-infrared light) to scan and take two-dimensional and three-dimensional images with micron-level resolution from the inside of an optical scattering medium (such as biological tissue). It is used for medical imaging and industrial non-destructive testing. Optical coherence tomography technology uses the principle of light interference, usually selects a longer wavelength near-infrared light to take a picture, and can penetrate a certain depth of scanning medium. Another similar technology, confocal microscopy, does not penetrate as deep as optical coherence tomography. The light source used by optical coherence tomography includes superluminescent diodes and ultra-short pulse lasers. Depending on the properties of the light source, this scanning method can even achieve sub-micron resolution, which requires the spectrum of the light source to be very wide, with a wavelength range of about 100 nanometers.

[0003] OCT is an optical interference imaging technology, which is quite similar to the Michelson interferometer commonly used in many engineering projects. It is composed of a light source, a reference light path, a measurement light path, and a screen. The biggest difference between OCT and Michelson interferometer is the choice of light source: Michelson interferometer usually uses a laser light source, which can have a long coherence distance, usually up to several meters. However, OCT usually uses a special low-coherence light source to illuminate the sample, such as a light-emitting diode (LED) or a superluminescent diode (SLD). It is precisely because of the difference in coherence characteristics that OCT has the ability of tomographic perspective. The swept laser light source used in current OCT still has some deficiencies in the optical interference image signal generated after the detector, such as side peaks, which affect the authenticity of the object to be detected and the observation.

[0004] Therefore, how to solve the above problems and deficiencies of the prior art is the subject of research and development for relevant industries. SUMMARY

[0005] To solve the above problems, the purpose of the present application is to provide a swept laser light source system with signal shaping.

[0006] The present invention provides a swept laser source system with signal shaping for connecting to an interferometer module and the interferometer module connects to a balanced detector, wherein the balanced detector outputs an optical interference waveform signal. The swept laser source system with signal shaping includes a fiber Fabry-Perot tunable filter, a beam wavelength controller, a first isolator, a laser beam amplifier, a signal shaper, a beam splitter and a second isolator. The fiber Fabry-Perot tunable filter receives a voltage signal to filter a received broadband beam and outputs a specific wavelength beam, wherein the voltage signal determines the wavelength range of the specific wavelength beam. The beam wavelength controller connects to the fiber Fabry-Perot tunable filter, the beam wavelength controller outputs the voltage signal to the fiber Fabry-Perot tunable filter according to a preset parameter, wherein the preset parameter determines the voltage value of the voltage signal. The first isolator connects to the output end of the fiber Fabry-Perot tunable filter to receive the specific wavelength beam, the first isolator outputs the specific wavelength beam in one direction. The laser beam amplifier connects to the output end of the first isolator, the laser beam amplifier initially emits the broadband beam and continuously amplifies the specific wavelength beam until the specific wavelength beam becomes the main beam, wherein the broadband beam cannot pass through the first isolator in reverse. The signal shaper connects to the laser beam amplifier, the signal shaper performs half-cycle filtering on the broadband beam and the specific wavelength beam according to a waveform shaping parameter, wherein the waveform shaping parameter has different gain values. The beam splitter connects the input end to the laser beam amplifier and the first output end to an interferometer module. The second isolator connects to the second output end of the beam splitter and the input end of the fiber Fabry-Perot tunable filter, the second isolator outputs the specific wavelength beam and the broadband beam in one direction.

[0007] In an embodiment of the present invention, the signal shaper performs signal shaping on the broadband beam and the specific wavelength beam according to different gain values.

[0008] In an embodiment of the present invention, the balanced detector connects to a computing processor, the computing processor performs Fourier transform on the optical interference waveform signal to obtain a three-dimensional information waveform signal.

[0009] In an embodiment of the present invention, after the signal shaper performs half-cycle filtering on the broadband beam and signal shaping on the broadband beam according to different gain values, the optical interference waveform signal is also half-cycle filtered and signal shaped, so that the peaks of the three-dimensional information waveform signal are converted to flat and symmetrical on both sides.

[0010] In an embodiment of the present invention, the beam splitter splits the specific wavelength beam by a one-to-one light quantity ratio.

[0011] In summary, the signal shaping swept frequency laser light source system provided by the present application can achieve the following effects:

[0012] 1. By performing half-cycle filtering and signal waveform adjustment on a specific wavelength beam of a wide spectrum light beam, a better optical interference waveform signal and three-dimensional information waveform signal are obtained; and

[0013] 2. The three-dimensional information authenticity of the object to be observed is adjusted simply by adjusting the gain value.

[0014] The following specific embodiments are described in detail, which can make the purpose, technical content, characteristics and effects of the present application more easily understood. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A block diagram of the signal shaping swept frequency laser light source system of the present application.

[0016] Figure 2 A block diagram of the signal shaping swept frequency laser light source system of the present application applied to an interferometer system.

[0017] Figure 3A A schematic diagram of a low-pass ideal waveform of the signal shaper of the present application.

[0018] Figure 3B Another schematic diagram of a low-pass ideal waveform of the signal shaper of the present application.

[0019] Figure 3C A schematic diagram of a low-pass actual waveform of the signal shaper of the present application.

[0020] Figure 4A A schematic diagram of an optical interference waveform signal without signal shaping of the present application in the prior art.

[0021] Figure 4B A schematic diagram of a three-dimensional information waveform signal without signal shaping of the present application in the prior art.

[0022] Figure 5A A schematic diagram of an optical interference waveform signal processed by the signal shaping swept frequency laser light source system of the present application.

[0023] Figure 5B A schematic diagram of a three-dimensional information waveform signal processed by the signal shaping swept frequency laser light source system of the present application.

[0024] Reference numerals: 100 - swept frequency laser source system with signal shaping; 110 - fiber Fabry-Perot tunable filter; 120 - beam wavelength controller; 130 - first isolator; 140 - laser beam amplifier; 150 - signal shaper; 160 - beam splitter; 170 - second isolator; 200 - interferometer module; 300 - balanced detector; 400 - operation processor; LS - optical interference waveform signal; T - three-dimensional information waveform signal; VS - voltage signal; WS - wide spectrum beam; AS - specific wavelength beam. DETAILED DESCRIPTION

[0025] In order to solve the problem of insufficient authenticity of the object to be detected in the existing three-dimensional tomography, the inventors have improved the existing products after years of research and development. The application will be described in detail below.

[0026] Please refer to Figures 1-2 , Figure 1 The block diagram of the swept frequency laser source system with signal shaping of the present application. Figure 2 The block diagram of the swept frequency laser source system with signal shaping of the present application applied to the interferometer system. As shown in the figure, the swept frequency laser source system with signal shaping 100 is connected to the interferometer module 200, and the interferometer module 200 is connected to a balanced detector 300, wherein the balanced detector 300 outputs an optical interference waveform signal LS, and the balanced detector 300 is connected to an operation processor 400, so that the operation processor 400 further processes the optical interference waveform signal LS. In the frequency domain optical coherence tomography, the wideband interference signal is obtained by the frequency domain separation detector, and the separation method can be achieved by using the time coding of the frequency of the variable frequency light source at different times or using the dispersive detector such as grating and linear detector array. According to the Wiener-Sinai theorem in Fourier transform, the autocorrelation function of the signal and its power spectral density are Fourier transform pairs of each other, so that the depth scanning can be immediately obtained by Fourier transform of the obtained frequency spectrum. In addition, the swept frequency laser source system with signal shaping 100 forms a loop inside, and the light beam in the loop is split by a beam splitter to the interferometer module 200 to perform optical interference effect.

[0027] Next, the details of the swept frequency laser source system with signal shaping 100 will be further described.

[0028] Please refer to Figures 1-5B , Figure 3A The low-pass ideal waveform diagram of the signal shaper of the present application. Figure 3B Another diagram of the low-pass ideal waveform of the signal shaper of the present application. Figure 3CA schematic diagram of a low pass actual waveform of the signal shaper of the present invention. Figure 4A A schematic diagram of an optical interference waveform signal without signal shaping of the prior art. Figure 4B A schematic diagram of a three-dimensional information waveform signal without signal shaping of the prior art. Figure 5A A schematic diagram of an optical interference waveform signal processed by the signal shaped swept laser source system of the present invention. Figure 5B A schematic diagram of a three-dimensional information waveform signal processed by the signal shaped swept laser source system of the present invention. The signal shaped swept laser source system 100 comprises a fiber Fabry-Perot tunable filter 110, a beam wavelength controller 120, a first isolator 130, a laser beam amplifier 140, a signal shaper 150, a beam splitter 160 and a second isolator 170. The fiber Fabry-Perot tunable filter 110 is configured to receive a voltage signal VS to filter a received wide spectrum beam WS and output a specific wavelength beam AS, wherein the voltage signal VS determines a wavelength range of the specific wavelength beam AS, and the specific wavelength beam AS refers to a beam located at a certain wavelength range. The beam wavelength controller 120 is connected to the fiber Fabry-Perot tunable filter 110, and the beam wavelength controller 120 is configured to output the voltage signal VS to the fiber Fabry-Perot tunable filter 110 according to a preset parameter, wherein the preset parameter determines a voltage value of the voltage signal VS. The first isolator 130 is connected to an output end of the fiber Fabry-Perot tunable filter 110 to receive the specific wavelength beam AS, and the first isolator 130 is configured to output the specific wavelength beam AS in a single direction. The laser beam amplifier 140 is connected to an output end of the first isolator 130 to receive the specific wavelength beam AS, and the laser beam amplifier 140 is configured to initially emit the wide spectrum beam WS, and continuously amplify the specific wavelength beam AS filtered by the fiber Fabry-Perot tunable filter 110 until the specific wavelength beam AS becomes the main beam in the loop, wherein the wide spectrum beam WS cannot pass through the first isolator 130 in a reverse direction. The signal shaper 150 is connected to the laser beam amplifier 140. An input end of the beam splitter 160 is connected to the laser beam amplifier 140, and a first output end and a second output end of the beam splitter 160 are respectively connected to an interferometer module 200 and the second isolator 170, wherein the beam splitter 160 splits the specific wavelength beam AS as the main beam in the loop in a one-to-one light quantity ratio. The second isolator 170 is connected to the second output end of the beam splitter 160 and an input end of the fiber Fabry-Perot tunable filter 110, and the second isolator 170 is configured to output the specific wavelength beam AS and the wide spectrum beam WS in a single direction, wherein the second isolator 170 has the same function as the first isolator 130, and the beams can only pass through in a single direction.

[0029] It should be noted that the signal shaper 150 of the present application is used to perform half-cycle filtering on the wide-spectrum light beam WS and the specific wavelength light beam AS according to a waveform shaping parameter, wherein the waveform shaping parameter has different gain values, wherein the gain values of the waveform shaping parameter can be set by the designer according to actual conditions to meet various actual needs. The signal shaper 150 performs signal shaping on the wide-spectrum light beam WS and the specific wavelength light beam AS according to different gain values, so that the signal waveform is closer to or equivalent to the authenticity of the three-dimensional information of the object to be observed. After the signal shaper 150 performs half-cycle filtering on the wide-spectrum light beam WS and signal shaping on the wide-spectrum light beam WS according to different gain values, the rear-end optical interference waveform signal LS is also half-cycle filtered and signal shaped, so that the wave peaks of the three-dimensional information waveform signal TS are converted to flat and symmetric.

[0030] Further, as shown in Figure 3A and Figure 3B , it is a filter waveform of an ideal signal shaper 150 and the gain values are all the same, which will perform half-cycle filtering on the wide-spectrum light beam WS and the specific wavelength light beam AS, but cannot reshape the signal waveform at this time, at which time the first half cycle or the second half cycle can be selected. In order to improve the side peak effect, the filter waveform of the signal shaper 150 shown in Figure 3C can be used to perform signal shaping on the wide-spectrum light beam WS and the specific wavelength light beam AS according to different gain values, so that the half-cycle optical interference waveform signal LS is more perfect, so as to improve the side peak effect after the optical interference waveform signal LS is sent into the operation processor 400 for Fourier transform, so that the signal waveform is closer to or equivalent to the authenticity. Therefore, according to the above description, Figure 4A , the optical interference waveform signal of the prior art is processed by the signal-shaped swept-frequency laser light source system 100 of the present application to become Figure 5A the optical interference waveform signal LS; Figure 4B , the three-dimensional information waveform signal of the prior art is processed by the signal-shaped swept-frequency laser light source system 100 of the present application to become Figure 5B the three-dimensional information waveform signal TS.

[0031] By comparing Figure 4A and Figure 5A , it can be seen that Figure 5A , only the front half of each cycle of the optical interference waveform signal LS has a waveform signal, and the rear half has no waveform signal, and the curvature at the side peak is also optimized and deformed. Next, by comparing Figure 4B and Figure 5B , it can be seen that the side peak of the three-dimensional information waveform signal TS is different from the three-dimensional information waveform signal of the prior art, Figure 4BThe side peak of the three-dimensional information waveform signal under the prior art is slightly high, which will affect the authenticity of the three-dimensional information of the object to be observed, and Figure 5B The side peak of the three-dimensional information waveform signal TS has been eliminated to zero, so the authenticity of the three-dimensional information of the object to be observed can be more completely presented.

[0032] In summary, the swept frequency laser light source system with signal shaping provided by the present application can achieve the following effects:

[0033] 1. By performing half-cycle filtering and signal waveform adjustment on the specific wavelength beam of the wide spectrum light beam, better optical interference waveform signals and three-dimensional information waveform signals are obtained; and

[0034] 2. The authenticity of the three-dimensional information of the object to be observed is optimized simply by adjusting the gain value.

[0035] The above only describes the preferred embodiments of the present application, and is not intended to limit the scope of the present application. Therefore, any equivalent changes or modifications made in accordance with the features and spirit of the present application described in the claims of the present application shall be included in the protection scope of the present application.

Claims

1. A swept laser source system with signal shaping for connecting to an interferometer module and the interferometer module is connected to a balanced detector, wherein the balanced detector outputs an optical interference waveform signal, characterized in that, The signal shaping swept laser source system comprises: a fiber Fabry-Perot tunable filter, which receives a voltage signal to filter a received broadband light beam and output a specific wavelength light beam, wherein the voltage signal determines the wavelength range of the specific wavelength light beam; a light beam wavelength controller connected to the fiber Fabry-Perot tunable filter, which outputs the voltage signal to the fiber Fabry-Perot tunable filter according to a preset parameter, wherein the preset parameter determines the voltage value of the voltage signal; a first isolator connected to the output end of the fiber Fabry-Perot tunable filter to receive the specific wavelength light beam, which unidirectionally outputs the specific wavelength light beam; a laser beam amplifier connected to the output end of the first isolator, which initially emits the broadband light beam and continuously amplifies the specific wavelength light beam until the specific wavelength light beam becomes the main light beam, wherein the broadband light beam cannot pass through the first isolator in the reverse direction; a signal shaper connected to the laser beam amplifier, which performs half-cycle filtering on the broadband light beam and the specific wavelength light beam according to a waveform shaping parameter, wherein the waveform shaping parameter has different gain values; a beam splitter, the input end of which is connected to the laser beam amplifier, and the first output end of which is connected to an interferometer module; and a second isolator connected to the second output end of the beam splitter and the input end of the fiber Fabry-Perot tunable filter, which unidirectionally outputs the specific wavelength light beam and the broadband light beam; wherein the balanced detector is connected to an operation processor, which performs Fourier transform on the optical interference waveform signal to obtain a three-dimensional information waveform signal, and after the signal shaper performs half-cycle filtering and signal shaping on the broadband light beam according to different gain values, the optical interference waveform signal can also be half-cycle filtered and signal shaped, so that the peaks of the three-dimensional information waveform signal are converted into flat and symmetrical.

2. The frequency-swept laser light source system with signal shaping as claimed in claim 1, wherein, The signal shaper performs signal shaping on the broadband light beam and the specific wavelength light beam according to different gain values.

3. The frequency swept laser source system with signal shaping as claimed in claim 1, wherein, The beam splitter splits the specific wavelength light beam by a one-to-one light quantity ratio. The signal shaping swept laser source system comprises:

Images