TWI830555B - Common path interferometric probe - Google Patents

Abstract

A common path interferometric probe for identifying a sample includes an optical fiber, a light conductor, a gradient-index (GRIN) lens component, a reflection surface and a beamsplitter surface. The optical fiber emits light rays, and the optical fiber, the light conductor and the GRIN lens component are connected to one another. The reflection surface is disposed on the light conductor and the beamsplitter surface is disposed in the GRIN lens component. When the light rays emitted by the optical fiber reach the beamsplitter surface through the light conductor, the beamsplitter surface reflects a part of the light rays to form a reference light and makes another part of the light rays pass through the beamsplitter surface to form a sample light. The reference light travels back to the optical fiber by the reflection of the reflection surface and the beamsplitter surface. The sample light reaches the sample after passing through the GRIN lens component, and then, it is reflected by the sample and travels back to the optical fiber.

Description

Common optical path interference probe

This application relates to a common optical path interference probe.

The traditional optical coherence tomography (OCT) system has two beams, one is the sample beam and the other is the reference beam. When the optical path lengths of the two beams are the same, interference signals will be generated to identify tissues or Sample.

Fiber optic OCT probes can be used for tomography images of trachea or brain tissue. However, during operation, the optical path difference between the two beams may change due to the movement or bending of the optical fiber, resulting in poor image quality or even failure to form an image. In addition, the fiber length of each probe produced has slight differences due to manufacturing tolerances. Therefore, every time a new probe is replaced, the optical path of the reference beam must be readjusted to the path length suitable for the new probe. This requires more time or human resources.

In order to improve the above problems, some industry players have developed common optical path probes to avoid changes in the optical path difference of the two beams due to movement or bending of the optical fiber. However, in conventional common optical path probes, a partial reflective surface is usually disposed on the end face of the self-focusing lens away from the optical fiber. Under such a configuration, it is difficult to effectively compensate for the two rays of light. The difference in optical path length of the beam affects the image quality. In addition, in order to ensure that the sample beam can be focused on the fiber end face, a balance needs to be struck between parameters such as the refractive index of the self-focusing lens, the length of the self-focusing lens, the distance between the self-focusing lens and the fiber, and the object distance between the probe and the sample. , however, this configuration makes it difficult to ensure that the reference beam can also be focused on the fiber end face at the same time, causing the return light spot of the reference beam to be too large, resulting in poor light collection efficiency of the reference beam.

The common optical path interference probe disclosed in this application is suitable for identifying a sample and includes an optical fiber, a light conductive element, a self-focusing lens component, a reflective surface and a light splitting surface. The optical fiber has an optical transceiver end face and is suitable for emitting a light beam from the optical transceiver end face. The light transmission element is suitable for transmitting light beams and has a first connection end face and a second connection end face opposite to each other, and the optical transceiver end face of the optical fiber is connected to the first connection end face. The self-focusing lens component is suitable for converging light beams and includes a connected collimating section and a focusing section. The focusing section is further away from the light conductive element than the collimating section. The self-focusing lens component has a joint surface, wherein the joint surface is located on a side of the collimating section away from the focusing section, and the joint surface is connected to the second connection end surface of the light conductive element. The reflective surface is disposed on the first connection end surface of the light conductive element and is located on one side of the light transceiver end surface, and the reflective surface is suitable for reflecting the reference light. The light splitting surface is arranged on the collimation section and is located substantially at half the length of the collimation section, wherein the light splitting surface and the reflection surface are arranged opposite to each other, and the light splitting surface is suitable for reflecting the reference light and transmitting the sampling light. Among them, the light beam is emitted from the light receiving and transmitting end face of the optical fiber. When it passes through the light conductive element and reaches the light splitting surface, part of the light beam will be reflected by the light splitting surface to form a reference light, and the other part will be reflected by the light splitting surface. The split beam will penetrate the splitting surface to form the sampling light. The reference light will return to the light transmitting and receiving end surface through reflection from the reflective surface and the splitting surface. The sampling light will reach the sample after penetrating the self-focusing lens component, and will be reflected by the sample and return. to the optical transceiver end.

The above description of the content of the present application and the following description of the embodiments are suitable to demonstrate and explain the principles of the present application, and provide further explanation of the patent application scope of the present application.

1,1b,1c,1d: Common optical path interference probe

10: Optical fiber

11: Optical transceiver end face

13:Core end face

20:Light conductive element

21: First connection end face

22: Second connection end face

30,30c: Self-focusing lens component

CP: collimation section

FP: focus segment

31: First self-focusing lens

32: Second self-focusing lens

321: First paragraph

322:Second paragraph

33:joint surface

34:Connection surface

35c: Wide diameter part

351c: Annular surface

36c: Narrow diameter part

361c: Front section

362c: rear section

37c: Junction

40: Reflective surface

50,50b,50c: spectroscopic surface

51,51c: Transmission area

52,52c: Reflective area

7d: Light turning element

8d: Protective glass

9:Sample

AD: axial

D1, D2: distance

FL,DL,EL,WL,AL1,AL2,GL,AL3: optical path

L1,L2,PFL: length

LF: beam

LR: reference light

LS: sampling light

△OPL: half optical path difference

R: reflectivity

RP: space

Figure 1 is a schematic diagram of a common optical path interference probe and a sample according to the first embodiment of the present application.

FIG. 2 is a schematic diagram of the first connection end face, the optical transceiver end face, the core end face and the reflective surface of FIG. 1 .

Figure 3 is a schematic front view of the light splitting surface of Figure 1.

Figure 4 is a schematic diagram of a common optical path interference probe and a sample according to the second embodiment of the present application.

Figure 5 is a schematic front view of the light splitting surface of Figure 4.

Figure 6 is a schematic diagram of a common optical path interference probe and a sample according to the third embodiment of the present application.

FIG. 7 is a schematic front view of the light splitting surface and annular surface of FIG. 6 .

Figure 8 is a schematic diagram of a common optical path interference probe and a sample according to the fourth embodiment of the present application.

The detailed features and advantages of the embodiments of the present application are described in detail below in the implementation mode. The content is sufficient to enable anyone with ordinary knowledge in the art to understand the technical content of the embodiments of the present application and implement them accordingly, and based on the disclosure of this specification Anyone with ordinary knowledge in the art can easily understand the relevant purposes and advantages of this application. The following examples further illustrate the concepts of this application in detail, but do not limit the scope of this application in any way.

Please refer to Figures 1 to 3. Figure 1 is a schematic diagram of a common optical path interference probe and a sample according to the first embodiment of the present application. Figure 2 is a first connection end face, an optical transceiver end face, and a core end face of Figure 1. and a schematic diagram of the reflective surface, and FIG. 3 is a schematic front view of the light splitting surface of the embodiment of FIG. 1 .

The common optical path interference probe 1 of this embodiment is suitable for identifying a sample 9 , and the common optical path interference probe 1 includes an optical fiber 10 , a light conductive element 20 , a self-focusing lens component 30 , a reflective surface 40 and a light splitting surface 50 .

The optical fiber 10 has an optical transceiver end face 11, and the optical fiber 10 is adapted to emit a light beam LF from the optical transceiver end face 11, and the wavelength of the light beam LF is, for example, in the range of 0.84 microns (μm) to 1.37 μm. In this embodiment, the optical fiber 10 is a single-mode optical fiber, and the optical fiber 10 has a core end face 13, wherein the core end face 13 is located at the axis of the optical transceiver end face 11, and the core end face 13 is suitable for transmitting and receiving the light beam LF. . However, the optical fiber of the present application is not limited to single-mode optical fiber. In other embodiments, the optical fiber may be, for example, a multi-mode optical fiber.

The light conductive element 20 is suitable for transmitting the light beam LF and has a relative first A connection end face 21 and a second connection end face 22, and the optical transceiver end face 11 of the optical fiber 10 is connected to the first connection end face 21. The area of the first connection end face 21 is larger than the area of the optical transceiver end face 11 . The light conductive element 20 is composed of an element with light conductive properties. In one embodiment, the light conductive element 20 can be a coreless fiber or cylindrical glass, and is not limited to those listed.

The self-focusing lens component 30 is suitable for converging the light beam LF and includes a connected collimation section CP and a focusing section FP, and the focusing section FP is farther away from the light conductive element 20 than the collimating section CP. The self-focusing lens component 30 has a joint surface 33 , where the joint surface 33 is located on the side of the collimating section CP away from the focusing section FP, and the joint surface 33 is connected to the second connection end surface 22 of the light conductive element 20 . Among them, the light beam LF after passing through the collimation section CP enters the focusing section FP as parallel light.

In this embodiment, the self-focusing lens component 30 includes a first self-focusing lens 31 and a second self-focusing lens 32 arranged coaxially, wherein the second self-focusing lens 32 is farther away from the light conductive element 20 than the first self-focusing lens 31 , the second self-focusing lens 32 is connected to the first self-focusing lens 31 , and there is a connecting surface 34 between the first self-focusing lens 31 and the second self-focusing lens 32 . In addition, the second self-focusing lens 32 includes a connected first section 321 and a second section 322 , wherein the first section 321 is connected to the first self-focusing lens 31 , and the first section 321 is in contact with the first self-focusing lens 31 . The lengths in the axial direction AD are substantially equal and together constitute the collimation section CP. In such a configuration, the joint surface 33 is located on the side of the first self-focusing lens 31 away from the second self-focusing lens 32 , and the connection surface 34 is located on the first self-focusing lens 31 and the second self-focusing lens 32 . between the first section 321 of the focal lens 32 . The lengths of the first section 321 of the second self-focusing lens 32 and the first self-focusing lens 31 in the axial direction AD are "substantially" equal, which means that the lengths of the two in the axial direction AD are equal, or that the lengths of the two in the axial direction AD are equal. The length in axial direction AD may vary by an amount within 15%, for example due to manufacturing tolerances.

The reflective surface 40 is provided on the first connection end surface 21 of the light conductive element 20 and is located on one side of the light transceiver end surface 11 , and the reflective surface 40 is suitable for reflecting the reference light LR. In this embodiment, the optical transceiver end face 11 of the optical fiber 10 is connected to the proximal axis of the first connection end face 21 of the light transmission element 20, and the reflective surface 40 is located off-axis of the first connection end face 21 and is an annular reflective surface. And the reflective surface 40 surrounds the light transmitting and receiving end surface 11 . The reflectivity of the reflective surface 40 may be 100% or close to 100%, but the application is not limited thereto. In other embodiments, the reflectivity of the reflective surface can be adjusted according to actual needs, for example, to be greater than 50% and less than or equal to 100%.

The light splitting surface 50 is provided on the collimation section CP and is substantially located at half the length of the collimation section CP, and the light splitting surface 50 is suitable for reflecting the reference light LR and transmitting the sampling light LS. Furthermore, the light splitting surface 50 is provided on the connection surface 34 between the first self-focusing lens 31 and the second self-focusing lens 32 , and the light splitting surface 50 and the reflection surface 40 are arranged opposite to each other. The half-length of the collimation section CP refers to the half-length of the collimation section CP in the axial direction AD, and can also be understood as the middle position of the collimation section CP in the axial direction AD. In addition, the said light splitting surface 50 is "substantially" located at half the length of the collimation section CP, which means that the distance D1 between the light splitting surface 50 and the joint surface 33 is equal to the distance D1 between the light splitting surface 50 and the collimation section CP and the focusing section FP. The distance between the junctions is D2, or minutes The distance D1 between the optical surface 50 and the joint surface 33 and the distance D2 between the light splitting surface 50 and the junction of the collimating section CP and the focusing section FP may have a difference within 15%, for example, due to manufacturing tolerances.

In this embodiment, as shown in Figure 3, the light splitting surface 50 has a transmission area 51 and a reflection area 52. The transmission area 51 is located at the paraxial (ie, inner circle) of the light splitting surface 50, and the reflection area 52 is located at the light splitting surface. 50° off-axis (i.e. outer ring). When the light beam LF emitted from the optical transceiver end face 11 of the optical fiber 10 passes through the light transmission element 20 and reaches the first self-focusing lens 31 in the self-focusing lens component 30 (or the first half of the collimation section CP), the light beam LF will be Collimate and split the light at 50° on the light splitting plane. Specifically, part of the light beam LF irradiating the transmission area 51 will penetrate the light splitting surface 50 to form the sampling light LS and enter the second self-focusing lens 32 , and the other part of the light beam LF irradiating the reflection area 52 will be reflected by the reflection area 52 The reference light LR is formed. Furthermore, the reflection area 52 of the light splitting surface 50 is an annular reflection surface, and the reflection area 52 surrounds the transmission area 51 . In this embodiment, the light splitting surface 50 and the reflecting surface 40 are parallel to each other and perpendicular to the axis AD.

Through the above configuration, the light beam LF emitted from the light transceiver end surface 11 can be split by the light splitting surface 50 to form the reference light LR and the sampling light LS. The reference light LR can return to the light transmitting and receiving end surface 11 through the reflection of the reflective area 52 in the reflective surface 40 and the light splitting surface 50 , while the sampling light LS can reach the sample after penetrating the second self-focusing lens 32 of the self-focusing lens component 30 9, and is reflected by the sample 9 and returns to the light transmitting and receiving end surface 11.

Specifically, as shown in FIG. 1 , the light beam LF is emitted from the core end surface 13 on the light transceiver end surface 11 to the light splitting surface 50 provided on the collimation section CP and is split into the reference light LR and the sampling light LS. The reference light LR is collimated by the collimation section CP and is emitted to the reflective surface 40 as a parallel collimated light ray, and then is reflected by the reflective surface 40 and emitted back to the reflective area 52 of the light splitting surface 50 , and finally passes through the light splitting surface 50 The reflection of the reflection area 52 and the collimation section CP converge to focus on the core end face 13 on the optical transceiver end face 11 . On the other hand, the sampling light LS is focused on the sample 9 through the collimation section CP and the focusing section FP of the self-focusing lens component 30, and then is reflected by the sample 9 and passes back through the self-focusing lens component 30, and penetrates the transmission area 51 And finally focus on the core end face 13 on the optical transceiver end face 11.

It is worth noting that since the light splitting surface 50 is located at half the length of the collimation section CP, the distance D1 that the reference light LR travels from the light splitting surface 50 to the light transmission element 20 is the same as the distance D1 that the sampling light LS travels from the light splitting surface 50 It travels to the distance D2 of the focusing section FP, so the reference light LR and the sampling light LS are both parallel collimated light rays when they first emerge from the collimating section CP.

In this embodiment, the reflection area 52 of the light splitting surface 50 is formed by an annular coating coated off-axis of the connection surface 34 , but the application is not limited to this. In other embodiments, the reflective area 52 may be formed by a reflective element disposed off-axis of the connecting surface 34 , such as a mirror. In addition, the reflectivity of the reflective area 52 may be 100% or close to 100%, but the application is not limited thereto. In other embodiments, the reflectivity of the reflective area can be adjusted according to actual design requirements, for example, greater than or equal to 50% and less than 100%.

The proportion of the range of the reflective surface 40 on the first connection end surface 21 shown in FIG. 2 is only an example, and the application is not limited thereto. In other embodiments, the reflective surface may have a range ratio different from that shown in FIG. 2 according to actual design requirements. Similarly, the range ratio of the transmission area 51 and the reflection area 52 of the light splitting surface 50 shown in FIG. 3 is only an example, and the application is not limited thereto. In other embodiments, the transmission area and the reflection area of the light splitting surface may have a range ratio different from that shown in FIG. 3 according to actual design requirements.

As shown in FIG. 1 , the optical path of the sampling light LS from the light splitting surface 50 to the sample 9 sequentially passes through the second half of the collimation section CP of the self-focusing lens component 30 (that is, the half of the collimation section CP farther away from the light conductive element 20 section) and the focusing section FP (i.e. the second self-focusing lens 32) and the air gap between the self-focusing lens member 30 and the sample 9. Therefore, the half optical path length L1 of the sampling light LS including the beam LF segment is the optical path FL of the light beam LF passing through the light conductive element 20, the optical path DL passing through the collimation section CP, the optical path EL passing through the focusing section FP, and the optical path EL passing through the self-focusing section. The sum of the optical lengths WL of the air space between the lens member 30 and the sample 9 (i.e., L1 = FL + DL + EL + WL). The air gap between the self-focusing lens component 30 and the sample 9 can be regarded as the working distance of the common optical path interference probe 1 .

On the other hand, the reference light LR sequentially passes through the first half of the collimation section CP of the self-focusing lens component 30 (that is, the half of the collimation section CP closer to the light conductive element 20) on the optical path from the light splitting surface 50 to the reflective surface 40. section) and the light conductive element 20. That is to say, the reference light LR passes through the light conductive element 20 and the first half of the collimation section CP twice on its optical path due to reflection from the reflective surface 40 . Therefore, the half-optical path length L2 of the reference light LR including the beam LF segment is the optical path FL of the light beam LF traveling through the light conductive element 20, the optical path 0.5DL traveling through the first half of the collimation section CP, and the reference light LR traveling through the collimation section CP. The sum of the first half optical path 0.5DL and the optical path FL traveling through the light conductive element 20 (ie, L2=FL+0.5DL+0.5DL+FL).

From the above description, it can be seen that the half-optical path difference △OPL between the reference light LR and the sampling light LS is the difference between the half-optical path length L2 of the reference light LR and the half-optical path length L1 of the sampling light LS, that is, △ OPL=L2-L1=(FL+0.5DL+0.5DL+FL)-(FL+DL+EL+WL)=FL-(EL+WL), where (EL+WL) is defined as the optical path length to be compensated, And FL is the compensation optical path length, where EL is the optical path of the sampling light LS traveling through the focusing section FP, WL is the optical path of the sampling light LS traveling through the air gap between the self-focusing lens component 30 and the sample 9, and FL is the optical path traveled by the light beam LF. The optical path of the light conductive element 20.

This application designs and adjusts the physical length of each element and the working distance of the common optical path interference probe 1 by matching the refractive index of the light conductive element 20 and the self-focusing lens component 30 in the common optical path interference probe 1, so that the compensation optical path length ( That is, FL) is essentially equal to the length of the optical path to be compensated (that is, EL+WL) to achieve the purpose of complete compensation or close to complete compensation of the optical path, so that the reference light LR and the sampling light LS have essentially the same optical path light path (that is, the half-optical path difference ΔOPL between the reference light LR and the sampling light LS is equal to zero). In this way, the uncompensated signal of the sampling light LS can be effectively compensated. Compensating the optical path, and at the same time effectively focusing the return light point of the reference light LR, thereby improving the light collection efficiency of the reference light LR.

The following provides a specific example of the common optical path interference probe 1 as well as the optical parameter range and condition settings.

First, the optical parameter range and condition settings include: 1. The wavelength range of the light beam LF emitted by the optical fiber 10 is 1.31 ± 0.06 μm; 2. The light transmission element 20 uses a fused silica coreless fiber, in which the fused silica coreless fiber The refractive index of the core optical fiber for the central wavelength of 1.31 μm of the beam LF and the two end value wavelengths of 1.37 μm and 1.25 μm are 1.44680, 1.44612, and 1.44748 respectively; and 3. The first self-focusing lens 31 and the second self-focusing lens 32 both adopt models It is a self-focusing lens of SLW-1.8. The refractive index of the SLW-1.8 self-focusing lens for the central wavelength of 1.31 μm and the two end value wavelengths of 1.37 μm and 1.25 μm of the beam LF are 1.59154, 1.59114 and 1.59201 respectively.

In the design of the common optical path interference probe 1, first determine the physical length of the focusing section FP of the self-focusing lens component 30 to be 2.332 millimeters (mm), and determine the air separation distance between the self-focusing lens component 30 and the sample 9 (i.e. working distance) is 2.0mm. Next, based on the refractive index of the second self-focusing lens 32 corresponding to the central wavelength of the light beam LF of 1.31 μm, it can be obtained that the optical path length to be compensated (EL+WL) is approximately 5.711 mm, that is, EL+WL=2.332 mm×1.59154+2.0 mm=5.711mm.

Then, based on the feature in this application that the compensated optical path length (FL) is substantially equal to the optical path length to be compensated (EL+WL), and based on the refractive index of the light transmission element 20 corresponding to the central wavelength of the light beam LF of 1.31 μm 1.44680, the physical length PFL of the light transmission element 20 can be calculated through the relationship equation FL=EL+WL=5.711mm, which is 3.947mm, that is, FL=PFL×1.44680=5.711mm, then PFL=5.711mm/1.44680=3.947mm .

Finally, the calculated physical length PFL of the light conductive element 20 is 3.947 mm, and the physical length of the collimation section CP can be simulated to be 1.873 mm.

In this embodiment, the physical length of the first self-focusing lens 31 is half of the physical length of the collimation section CP, so the physical length of the first self-focusing lens 31 is 0.9365 mm. Moreover, the physical length of the first section 321 of the second self-focusing lens 32 is half of the physical length of the collimation section CP, and the physical length of the second section 322 of the second self-focusing lens 32 is the physical length of the focusing section FP, so The physical length of the second self-focusing lens 32 is 3.2685mm (that is, 0.9365mm+2.332mm=3.2685mm).

The configuration of the above-mentioned specific example of the common optical path interference probe 1 can ensure that the entire wavelength range of the beam LF of 1.31±0.06 μm can achieve the effect of complete optical path compensation or close to complete compensation.

Specifically, for one of the end value wavelengths of the beam LF, 1.37μm, the optical path length to be compensated (EL+WL) is approximately 5.711mm (i.e. 2.332mm×1.59114+2.0mm=5.711mm), and the compensated optical path length ( FL) is about 5.709 mm (ie 3.947mm×1.44612=5.709mm), so the difference between the compensated optical path length (FL) and the optical path length to be compensated (EL+WL) is 0.002mm, which is much smaller than the work of the common optical path interference probe 1 distance (2.0mm). It can be seen that the end value part of the wavelength 1.37 μm in the beam LF can also achieve a nearly complete compensation effect in the common optical path interference probe 1.

On the other hand, for the other end value wavelength of the beam LF, 1.25μm, the optical path length to be compensated (EL+WL) is approximately 5.713mm (i.e. 2.332mm×1.59201+2.0mm=5.713mm), and the compensated optical path length ( FL) is about 5.715mm (ie 3.947mm×1.44748=5.715mm), so the difference between the compensated optical path length (FL) and the optical path length to be compensated (EL+WL) is 0.002mm, which is much smaller than the common optical path Working distance of interference probe 1 (2.0mm). It can be seen from this that the end value part of the wavelength 1.25 μm in the beam LF can also achieve a nearly complete compensation effect in the common optical path interference probe 1.

Through the above configuration, the common optical path interference probe 1 in this embodiment can make the optical path FL of the light beam LF (or reference light LR) pass through the light transmission element 20, which is essentially equal to the optical path FL of the sampling light LS from the collimation section CP and the focusing section FP. The junction travels to the optical path of sample 9 (EL+WL), that is, the compensated optical path length (FL) is essentially equal to the optical path length to be compensated (EL+WL). It should be noted that the compensated optical path length (FL) is essentially equal to the optical path length to be compensated (EL+WL), which refers to the sum of the compensated optical path length (FL) and the optical path length to be compensated (EL+WL). The difference between is much smaller than the optical path (that is, the working distance) between the common optical path interference probe 1 and the sample 9, and the "much smaller than" mentioned in this article refers to a number A value that is two orders of magnitude smaller than another value (that is, a difference of one hundred times).

Furthermore, in the above specific example, the coating range of the reflective area 52 of the light splitting surface 50 can be determined. Specifically, the optical fiber 10 can be a single-mode optical fiber model SMF-28, which has a mode field diameter (Mode Field Diameter) of 9.2 μm at a central wavelength of 1.31 μm. After calculation, if the light beam LF with a central wavelength of 1.31 μm is emitted from the optical fiber 10 and reaches the second connection end face 22 of the light transmission element 20, the radius on the second connection end face 22 is approximately 0.244 mm. Considering the wavelength range of the beam LF is 1.31 ± 0.06 μm, and the beam LF is regarded as a Gaussian beam that approximately satisfies the Gaussian function, then the part of the beam LF within the radius of 0.31 mm on the second connection end face 22 is included. 96% of the energy in the entire Gaussian beam. Then, when the light beam LF within the radius of 0.31 mm on the second connection end face 22 travels to the light splitting surface 50, the corresponding radius on the light splitting surface 50 expands to 0.362 mm after passing through the first half of the collimation section CP. Therefore, on the connection surface 34 provided with the light splitting surface 50, a reflective film is coated on the area other than the radius of 0.362 mm of the connection surface 34 to form the reflection area 52, so that the area within the radius of 0.362 mm of the connection surface 34 is the transmission area 51. Under such a range configuration, the part containing 96% of the energy in the light beam LF can be transmitted to become the sampling light LS, and the remaining part is reflected by the reflection area 52 to become the reference light LR.

Please refer to Figures 1, 4 and 5 at the same time. Figure 4 is a schematic diagram of a common optical path interference probe and a sample according to the second embodiment of the present application, and Figure 5 is a schematic front view of the light splitting surface of Figure 4. The common optical path of this embodiment (corresponding to Figure 4) The interference probe 1 b is similar to the aforementioned common optical path interference probe 1 in FIG. 1 , and uses the same numbers to represent the same components. The functions and effects of each component are the same as the above, and will not be described again here.

Like the common optical path interference probe 1 of the first embodiment, the light splitting surface 50 has a transmission area 51 and a reflection area 52 . However, in the common optical path interference probe 1b of the second embodiment, the light splitting surface 50b covers the entire area of the connection surface 34 as a partial reflection surface. Moreover, the reflectivity of the light splitting surface 50b can be between 4% and 50% according to actual design requirements, and the present application is not limited to this. Specifically, since the light splitting surface 50b is a partially reflective surface, when the light beam LF reaches the light splitting surface 50b from the light transmitting and receiving end surface 11 through the light conductive element 20 and the first self-focusing lens 31, the light beam LF will be partially reflected by the light splitting surface 50b. and partially penetrate to form the reference light LR and the sampling light LS respectively. Therefore, the formed reference light LR will not be collimated and incident only on the off-axis (ie, outer ring) of the first connection end face 21 as in the first embodiment (corresponding to FIG. 1), but will be collimated and incident on the entire first connection. End face 21. Based on this, the area of the reflective surface 40 can be increased adaptively and spread over the rest of the first connection end surface 21 of the light conductive element 20 except for the light transceiver end surface 11 to avoid the reduction in the light collection efficiency of the reference light LR.

In this embodiment, the light splitting surface 50b is formed by a coating coated on the entire connection surface 34, but the application is not limited to this. In other embodiments, the light splitting surface 50b may be formed by a reflective element disposed on the connection surface 34, such as a mirror.

In addition, based on the aforementioned optical parameter range and condition settings, the reflectance R of the light splitting surface 50b of this embodiment can be determined. Specifically, it is assumed that the reflective surface 40 is spread over the remaining area of the first connection end surface 21 of the light conductive element 20 except for the light transceiver end surface 11 , and the reflectivity of the reflective surface 40 is approximately 100%. Furthermore, it is assumed that the reflectivity of sample 9 is 4%, and the material of the common optical path interference probe 1b does not absorb light. Then the light return ratio of the reference light LR is approximately R×100%×R=R ² , and the light return ratio of the sampling light LS is (1-R)×4%×(1-R)=0.04×(1-R ) ² , where R is the reflectivity of the light splitting surface 50b. When the light receiving intensities of the reference light LR and the sampling light LS are the same, the system using the common optical path interference probe 1b can obtain the maximum signal contrast. Therefore, by making the return ratio of the reference light LR equal to the return ratio of the sampling light LS, that is, R ² =0.04×(1-R) ² , it can be calculated that the reflectivity R of the light splitting surface 50b is approximately 16.7%. Under this situation, the common optical path interference probe 1b has good signal contrast.

Please refer to FIGS. 6 and 7 . FIG. 6 is a schematic diagram of a common optical path interference probe and a sample according to the third embodiment of the present application, and FIG. 7 is a schematic front view of the light splitting surface and annular surface of FIG. 6 . The common optical path interference probe 1c of this embodiment (corresponding to Figure 6) is similar to the aforementioned common optical path interference probe 1 of Figure 1, and the same components are represented by the same numbers. The functions and effects of each component are the same as the above. This will not be described again.

It should be noted that the self-focusing lens component 30c in the common optical path interference probe 1c of this embodiment includes an integrally formed wide-diameter portion 35c and a narrow-diameter portion 36c, wherein the outer diameter of the wide-diameter portion 35c is larger than the narrow-diameter portion 36c has an outer diameter, and the narrow-diameter portion 36c is farther away from the light-conducting element 20 than the wide-diameter portion 35c. There is a junction 37c between the narrow diameter part 36c and the wide diameter part 35c, and the wide diameter part 35c has a ring surrounding the junction 37c shaped surface 351c. In addition, the narrow-diameter portion 36c includes a connected front section 361c and a rear section 362c, wherein the front section 361c is connected to the wide-diameter section 35c, and the lengths of the front section 361c and the wide-diameter section 35c in the axial direction AD are substantially equal and together form a collimated Section CP. In such a configuration, the joint surface 33 is located on the side of the wide-diameter portion 35c away from the narrow-diameter portion 36c. The lengths of the front section 361c of the narrow-diameter portion 36c and the wide-diameter portion 35c in the axial direction AD are "substantially" equal, which means that the lengths of the two in the axial direction AD are equal, or the lengths of the two in the axial direction AD. There may be variations within 15%, for example due to manufacturing tolerances.

The light splitting surface 50c is provided on the collimation section CP and is substantially located at half the length of the collimation section CP, and the light splitting surface 50c is suitable for reflecting the reference light LR and transmitting the sampling light LS. Further, as shown in FIG. 7 , the light splitting surface 50c has a transmission area 51c and a reflection area 52c. The transmission area 51c is located at the junction 37c of the wide diameter portion 35c and the narrow diameter portion 36c of the self-focusing lens member 30c, and reflects The area 52c is located on the annular surface 351c of the wide-diameter portion 35c, so that the reflective area 52c is an annular reflective surface and surrounds the transmission area 51c. The mechanism by which the light beam LF emitted from the optical fiber 10 forms the sampling light LS and the reference light LR, and the mechanism by which the sampling light LS and the reference light LR return light are the same as those of the common optical path interference probe 1 of the first embodiment, and there are no differences here. Let me repeat it again. Therefore, it can be seen that the transmission area 51c is suitable for transmitting the sampling light LS, and the reflection area 52c is suitable for reflecting the reference light LR. In this embodiment, the light splitting surface 50c and the reflective surface 40 are arranged opposite to each other, and the light splitting surface 50c and the reflective surface 40 are parallel to each other and perpendicular to the axis AD. The half length of the collimation section CP refers to the collimation section CP Half the length in the axial direction AD can also be understood as the middle position of the collimation section CP in the axial direction AD. In addition, the light splitting surface 50c is "substantially" located at half the length of the collimation section CP, which means that the distance D1 between the light splitting surface 50c and the joint surface 33 is equal to the distance D1 from the light splitting surface 50c to the collimation section CP and the focusing section FP. The distance D2 at the junction, or the distance D1 between the light splitting surface 50c and the joint surface 33 and the distance D2 between the light splitting surface 50c and the junction of the collimation section CP and the focusing section FP may have a difference of 15% due to manufacturing tolerances, for example. The difference within %.

Through the above configuration, the light beam LF emitted from the light transmitting and receiving end surface 11 can be split by the light splitting surface 50c to form the reference light LR and the sampling light LS. The reference light LR can return to the optical transceiver end face 11 through the reflection of the reflective area 52c in the reflective surface 40 and the light splitting surface 50c, so that the sampling light LS of the light beam LF emitted from the optical transceiver end face 11 can pass through the self-focusing lens 30c The narrow diameter portion 36c then reaches the sample 9, and is reflected by the sample 9 and returns to the light transmitting and receiving end surface 11.

In this embodiment, the reflection area 52c of the light splitting surface 50c is formed by an annular coating coated on the annular surface 351c, but the application is not limited to this. In other embodiments, the reflective area 52c may be formed by a reflective element disposed on the annular surface 351c, such as a mirror. In addition, the reflectivity of the reflective area 52c may be 100% or close to 100%, but the application is not limited thereto. In other embodiments, the reflectivity of the reflective area can be adjusted, for example, to be greater than or equal to 50% and less than 100% according to actual design requirements.

In this embodiment, although the self-focusing lens component 30c includes an integrally formed wide-diameter portion 35c and a narrow-diameter portion 36c, it is different from the self-focusing lens component of the first embodiment. The mirror component 30 is different in appearance, but by comparing the two, it can still be found that the wide diameter portion 35c and the narrow diameter portion 36c in the self-focusing lens component 30c are both the same as those of the self-focusing lens component 30 in terms of function and optical parameter design. The first self-focusing lens 31 and the second self-focusing lens 32 are the same and will not be described again here.

Similar to the design of various optical parameters in the aforementioned first embodiment, correspondingly in this embodiment, the physical length of the wide-diameter portion 35c is 0.9365 mm. Furthermore, the physical length of the narrow-diameter portion 36c is 3.2685mm (that is, 0.9365mm+2.332mm=3.2685mm). After determining the respective physical lengths of the wide-diameter portion 35c and the narrow-diameter portion 36c of the self-focusing lens component 30c and determining the outer diameter of the narrow-diameter portion 36c according to actual design requirements, part of the self-focusing lens component can be removed through etching or other methods. To form the narrow diameter portion 36c (the space RP marked in FIG. 6 indicates the space where the portion of the self-focusing lens member removed through etching is located before being removed). Therefore, after the narrow diameter portion 36c is formed, the annular surface 351c is formed on the wide diameter portion 35c. Next, an annular coating can be coated on the annular surface 351c to form the reflection area 52c of the light splitting surface 50c. The etching can be, for example, dry etching or wet etching, but the application is not limited thereto. In addition, wet etching can, for example, use a buffer solution composed of ammonium fluoride and hydrofluoric acid (NH ₄ F + HF) to etch the self-focusing lens component, but the present application is not limited thereto.

Furthermore, in the aforementioned specific example, the coating range of the reflection area 52c of the light splitting surface 50c can be determined, so that the outer diameter of the narrow diameter portion 36c can be determined. Specifically, the optical fiber 10 can be a single-mode optical fiber model SMF-28, which has a mode field diameter (Mode Field Diameter) of 9.2 μm at a central wavelength of 1.31 μm. After calculation, If the light beam LF with a central wavelength of 1.31 μm is emitted from the optical fiber 10 and reaches the second connection end face 22 of the light transmission element 20, the radius on the second connection end face 22 is approximately 0.244 mm. Considering the wavelength range of the beam LF is 1.31 ± 0.06 μm, and the beam LF is regarded as a Gaussian beam that approximately satisfies the Gaussian function, then the part of the beam LF within the radius of 0.31 mm on the second connection end face 22 is included. 96% of the energy in the entire Gaussian beam. Then, when the light beam LF within the radius of 0.31 mm on the second connection end face 22 travels to the light splitting surface 50c, the corresponding radius on the light splitting surface 50c expands to 0.362 mm after passing through the first half of the collimation section CP. Therefore, the radius of the narrow-diameter portion 36c can be designed to be 0.362 mm to correspond to the transmission area 51c of the light splitting surface 50c, and then the inner diameter of the annular surface 351c of the wide-diameter portion 35c can be determined. On the other hand, since the junction 37c of the narrow-diameter portion 36c and the wide-diameter portion 35c defines the transmission area 51c, the outer diameter of the transmission area 51c is the outer diameter of the narrow-diameter portion 36c. Therefore, such a range of the transmission region 51c allows the part containing 96% of the energy in the light beam LF to penetrate and become the sampling light LS, while the remaining part of the light beam LF is reflected by the reflection area 52c and becomes the reference light LR.

Please refer to FIG. 1 and FIG. 8 at the same time. FIG. 8 is a schematic diagram of a common optical path interference probe and a sample according to the fourth embodiment of the present application. The common optical path interference probe 1d of this embodiment (corresponding to Figure 8) is similar to the aforementioned common optical path interference probe 1 of Figure 1, and the same components are represented by the same numbers. The functions and effects of each component are the same as the above. This will not be described again.

It should be noted that the common optical path interference probe 1d of this embodiment further includes A light deflection element 7d and a protective glass 8d.

The light turning element 7d is disposed between the self-focusing lens member 30 and the sample 9, and the light turning element 7d is adapted to turn the sampling light LS. In this embodiment, the light turning element 7d is a reflecting mirror, but the application is not limited thereto. In other embodiments, the light turning element may be a lens, for example.

The protective glass 8d is disposed between the light turning element 7d and the sample 9, and the protective glass 8d is suitable for providing protection for the common optical path interference probe 1d to prevent the element from directly contacting the sample 9, and to prevent foreign matter from entering the common optical path interference probe 1d. .

Through the above configuration, the light beam LF is emitted from the core end surface 13 on the light transceiver end surface 11 to the light splitting surface 50 provided on the collimation section CP and is split into the reference light LR and the sampling light LS. The path of the reference light LR is the same as the aforementioned first embodiment, and will not be described again. After the sampling light LS is collimated and focused by the second self-focusing lens 32, it first enters the light turning element 7d, and changes its transmission direction through the turning of the light turning element 7d to travel towards the sample 9. In addition, the sampling light LS passes through the protective glass 8d after turning and is focused on the sample 9. Then, after being reflected by the sample 9, the sampling light LS first penetrates the protective glass 8d along the original path to reach the light turning element 7d, and changes the transmission direction through the turning of the light turning element 7d to travel towards the self-focusing lens member 30, and finally returns to Optical transceiver end face 11.

As shown in FIG. 8 , the optical path of the sampling light LS from the light splitting surface 50 to the sample 9 sequentially passes through the second half of the collimation section CP of the self-focusing lens component 30 (that is, the half of the collimation section CP farther away from the light conductive element 20 segment) and the focus segment FP (i.e. the second The air space between the self-focusing lens 32), the self-focusing lens member 30 and the light turning element 7d, the air space between the light turning element 7d and the protective glass 8d, the protective glass 8d, and the air space between the protective glass 8d and the sample 9 . Therefore, the half-optical path length L1 of the sampling light LS including the beam LF segment is the optical path FL of the light beam LF passing through the light conductive element 20, the optical path DL passing through the collimation section CP, the optical path EL passing through the focusing section FP, and the optical path EL passing through the self-focusing section. The optical path AL1 of the air gap between the lens member 30 and the light deflection element 7d, the optical path AL2 of the air gap between the light deflection element 7d and the protective glass 8d, the optical path GL of the protective glass 8d, and the optical path GL of the protective glass 8d and the sample 9 The sum of the optical paths AL3 between the air intervals (i.e. L1=FL+DL+EL+AL1+AL2+GL+AL3). Among them, the optical path between the self-focusing lens component 30 and the sample 9 can be regarded as the working distance of the common optical path interference probe 1d (ie, AL1+AL2+GL+AL3). On the other hand, the path of the reference light LR in this embodiment is the same as that in the first embodiment. Therefore, the half optical path length L2 of the reference light LR including the beam LF segment is the optical path FL, The sum of the optical path 0.5DL of the first half of the collimation section CP, the optical path 0.5DL of the reference light LR passing through the first half of the collimation section CP, and the optical path FL passing through the light conductive element 20 (i.e. L2=FL+0.5DL+ 0.5DL+FL).

From the above description, it can be seen that the half-optical path difference △OPL between the reference light LR and the sampling light LS is the difference between the half-optical path length L2 of the reference light LR and the half-optical path length L1 of the sampling light LS, that is, △ OPL=L2-L1=(FL+0.5DL+0.5DL+FL)-(FL+DL+EL+AL1+AL2+GL+AL3)=FL-(EL+AL1+AL2+GL+AL3), where defined (EL+AL1+AL2+GL+AL3) is to be Compensation optical path length, and FL is the compensation optical path length, where EL is the optical path of the sampling light LS traveling through the focusing section FP, AL1 is the optical path of the sampling light LS traveling through the air gap between the self-focusing lens component 30 and the light turning element 7d, AL2 is the optical path of the sampling light LS traveling through the air gap between the light turning element 7d and the protective glass 8d, GL is the optical path of the sampling light LS traveling through the protective glass 8d, AL3 is the optical path of the sampling light LS traveling through the air between the protective glass 8d and the sample 9 spaced optical path, and FL is the optical path of the light beam LF traveling through the light conductive element 20 .

This application designs and adjusts the physical length of each element and the working distance of the common optical path interference probe 1d by matching the refractive index of the light conduction element 20 and the self-focusing lens component 30 in the common optical path interference probe 1d, so as to compensate for the optical path length ( That is, FL) is essentially equal to the length of the optical path to be compensated (that is, EL+AL1+AL2+GL+AL3) to achieve the purpose of complete compensation or close to complete compensation of the optical path, thereby making the substantial difference between the reference light LR and the sampling light LS have the same optical path length (that is, the half-optical path difference ΔOPL between the reference light LR and the sampling light LS is equal to zero). Thereby, the optical path to be compensated of the sampling light LS can be effectively compensated, and the return light point of the reference light LR can be effectively focused at the same time, thereby improving the light collection efficiency of the reference light LR.

The following provides a specific example of the common optical path interference probe 1d as well as the optical parameter range and condition settings.

First, the optical parameter range and condition settings include: 1. The wavelength range of the beam LF emitted by the optical fiber 10 is 0.88±0.04μm; 2. The light transmission element 20 uses fused silica coreless fiber. The refractive index of the fused silica coreless fiber for the central wavelength of the beam LF of 0.88 μm and the two end wavelengths of 0.92 μm and 0.84 μm is 1.45190 and 0.84 μm, respectively. 1.45147 and 1.45266; 3. The first self-focusing lens 31 and the second self-focusing lens 32 both adopt the model SLW-2.0 self-focusing lens, where the SLW-2.0 self-focusing lens has a central wavelength of 0.88 μm and two end values for the beam LF The refractive indices at wavelengths of 0.92μm and 0.84μm are 1.59731, 1.59642 and 1.59834 respectively; and 4. The protective glass 8d is made of organic glass (Polymethyl methacrylate, PMMA), in which the central wavelength of the organic glass at the beam LF is 0.88μm and the two end values The refractive indices at wavelengths of 0.92μm and 0.84μm are 1.48458, 1.48408 and 1.48515 respectively.

In the design of the common optical path interference probe 1d, it is first determined that the physical length of the focusing section FP of the self-focusing lens component 30 is 2.247mm, the air separation distance between the self-focusing lens component 30 and the optical turning element 7d is 1.5mm, and the optical turning element The air separation distance between 7d and protective glass 8d is 0.8mm, the physical length of protective glass 8d is 0.2mm, and the air separation distance between protective glass 8d and sample 9 is determined to be 0.5mm. Next, according to the refractive index of the second self-focusing lens 32 corresponding to the central wavelength of the light beam LF of 0.88 μm, which is 1.59731, and the refractive index of the protective glass 8d which is 1.48458, the optical path length to be compensated (EL+AL1+AL2+ GL+AL3) is about 6.686mm, that is, EL+AL1+AL2+GL+AL3=2.247mm×1.59731+1.5mm+0.8mm+0.2 mm×1.48458+0.5mm=6.686mm.

Then, based on the characteristics of the compensation optical path length (FL) in this application that is substantially equal to the optical path length to be compensated (EL+AL1+AL2+GL+AL3), and based on the light transmission corresponding to the central wavelength of the beam LF of 0.88 μm The refractive index of the element 20 is 1.45190. The physical length PFL of the light transmission element 20 can be found to be 4.605mm through the relationship FL=EL+AL1+AL2+GL+AL3=6.686mm, that is, FL=PFL×1.45190=6.686 mm, then PFL=6.686mm/1.45190=4.605mm.

Finally, the calculated physical length PFL of the light conductive element 20 is 4.605 mm, and the physical length of the collimation section CP can be simulated to be 0.804 mm.

In this embodiment, the physical length of the first self-focusing lens 31 is half of the physical length of the collimation section CP, so the physical length of the first self-focusing lens 31 is 0.402 mm. Moreover, the physical length of the first section 321 of the second self-focusing lens 32 is half of the physical length of the collimation section CP, and the physical length of the second section 322 of the second self-focusing lens 32 is the physical length of the focusing section FP, so The physical length of the second self-focusing lens 32 is 2.649mm (that is, 0.402mm+2.247mm=2.649mm).

The configuration of the specific example of the above-mentioned common optical path interference probe 1d can ensure that the entire wavelength range of the beam LF of 0.88±0.04μm can achieve the effect of complete optical path compensation or close to complete compensation.

Specifically, for one of the end value wavelengths of the beam LF, 0.92μm, the optical path length to be compensated (EL+AL1+AL2+GL+AL3) is approximately 6.684mm (i.e. 2.247mm×1.59642+1.5mm+0.8mm+0.2 mm×1.48408+0.5mm=6.684mm), and the compensation optical path length (FL) is approximately 6.684mm (i.e. 4.605 mm×1.45147=6.684mm), so the difference between the compensated optical path length (FL) and the optical path length to be compensated (EL+AL1+AL2+GL+AL3) is 0. It can be seen that the end value part with a wavelength of 0.92 μm in the beam LF can also achieve a complete compensation effect in the common optical path interference probe 1d.

On the other hand, for the other end value wavelength of the beam LF, 0.84μm, the optical path length to be compensated (EL+AL1+AL2+GL+AL3) is approximately 6.688mm (i.e. 2.247mm×1.59834+1.5mm+0.8mm+0.2 mm×1.48515+0.5mm=6.688mm), and the compensated optical path length (FL) is about 6.689mm (i.e. 4.605mm×1.45266=6.689mm), so that the compensated optical path length (FL) and the optical path length to be compensated (EL +AL1+AL2+GL+AL3) is 0.001mm, which is much smaller than the working distance of the common optical path interference probe 1d (i.e. AL1+AL2+GL+AL3=1.5mm+0.8mm+0.2mm×1.48458+ 0.5mm=3.097mm). It can be seen that the end value part of the wavelength 0.84 μm in the beam LF can also achieve a nearly complete compensation effect in the common optical path interference probe 1d.

Through the above configuration, the common optical path interference probe 1d in this embodiment can make the optical path FL of the light beam LF traveling through the light conductive element 20 substantially equal to the sampling light LS traveling from the junction of the collimation section CP and the focusing section FP to the sample. 9 optical path (EL+AL1+AL2+GL+AL3), that is, the compensated optical path length (FL) is essentially equal to the optical path length to be compensated (EL+AL1+AL2+GL+AL3). It should be noted that the compensation optical path length (FL) is essentially equal to the optical path length to be compensated (EL+AL1+AL2+GL+AL3), which refers to the compensation optical path length (FL) and the optical path length to be compensated. (EL+AL1+AL2+GL+AL3) is much smaller than that of the common optical path interference probe The optical path (i.e., working distance) between 1d and sample 9, and "much less than" mentioned herein means that one value is smaller than the other value by two orders of magnitude (i.e., the difference is up to one hundred times).

In the description of the above embodiments, the "perpendicular" means that the relationship between the two elements is substantially perpendicular to each other, and the "parallel" means that the relationship between the two elements is substantially parallel to each other, either of which can be Includes slight errors due to manufacturing tolerances, for example.

According to the common optical path interference probe of the above embodiment, by arranging the light splitting surface in the collimation section and substantially at half the length of the collimation section, part of the light beam is reflected by the light splitting surface as the reference light, and part of the light beam penetrates the light splitting surface. As the sampling light, the reference light can return to the optical transceiver end surface along the original path through reflection from the reflective surface, while the sampling light is reflected by the sample and returns to the optical transceiver end surface along the original path. Thereby, the physical lengths of the light transmission element and the self-focusing lens component can be adjusted according to the optical path lengths of the reference light and the sampling light, ensuring that the optical paths of the reference light and the sampling light are substantially equal to each other, and allowing the reference light and the sampling light to pass through After reflection, it can be focused on the optical transceiver end face of the optical fiber, thereby ensuring the light collection efficiency of the reference light and the sampling light at the same time, effectively compensating the optical path to be compensated for the sampling light, and at the same time effectively focusing the return light spot of the reference light. The purpose is to provide stable tissue cross-sectional images in handheld or dynamic operation environments, to assist medical staff in more accurately judging the status of tissues or samples, and to reduce unnecessary time and labor costs.

In addition, by setting the light splitting surface at half the length of the collimation section, it is helpful to determine the optical path length to be compensated and the compensation optical path length of the common optical path interference probe. The positional relationship between the light conductive element and the self-focusing lens component can be simply derived from the physical length of the focusing section and the working distance of the common optical path interference probe, and is simulated by the physical length of the light conductive element By determining the physical length of the collimation section, the purpose of effectively compensating the optical path of the sampling light to be compensated can be more easily achieved.

Although the present application has been disclosed with the foregoing preferred embodiments, they are not intended to limit the present application. Anyone skilled in the similar art may make slight changes and modifications without departing from the spirit and scope of the present application. Therefore, this application is The scope of patent protection applied for shall be determined by the scope of patent application attached to this specification.

1: Common optical path interference probe

10: Optical fiber

11: Optical transceiver end face

20:Light conductive element

21: First connection end face

22: Second connection end face

30:Self-focusing lens component

CP: collimation section

FP: focus segment

31: First self-focusing lens

32: Second self-focusing lens

321: First paragraph

322:Second paragraph

33:joint surface

34:Connection surface

40: Reflective surface

50: Spectral surface

9:Sample

AD: axial

D1: distance

D2: distance

LF: beam

LR: reference light

LS: sampling light

PFL: length

Claims (13)

A common optical path interference probe, suitable for identifying a sample, the common optical path interference probe includes: an optical fiber having an optical transceiver end face, and the optical fiber is suitable for emitting a light beam from the optical transceiver end face; a light conductive element, suitable for The light beam is transmitted and has an opposite first connection end face and a second connection end face, and the optical transceiver end face of the optical fiber is connected to the first connection end face; a self-focusing lens component is suitable for condensing the light beam and includes a connected a collimating section and a focusing section, the focusing section is further away from the light conductive element than the collimating section, the self-focusing lens component has a joint surface, the joint surface is located on a side of the collimating section away from the focusing section, and The joint surface is connected to the second connection end surface of the light conductive element; a reflective surface is provided on the first connection end surface of the light conductive element and is located on one side of the light transceiver end surface, and the reflective surface is suitable for reflecting a Reference light; and a light-splitting surface provided on the collimation section and substantially located at half the length of the collimation section, the light-splitting surface and the reflective surface are arranged opposite to each other, and the light-splitting surface is adapted to reflect the reference light and For transmitting a sampled light; wherein, the light beam is emitted from the light receiving and transmitting end face of the optical fiber. When it passes through the light conductive element and reaches the light splitting surface, part of the light beam will be reflected by the light splitting surface to form the reference light, and the other part of the light beam will be reflected by the light splitting surface. It will penetrate the light splitting surface to form the sampling light, and the reference light will return to the light receiving and transmitting end surface through the reflection of the reflecting surface and the light splitting surface, and the sampled light will The sample light reaches the sample after penetrating the self-focusing lens component, and is reflected by the sample and returns to the light transmitting and receiving end face, wherein the light splitting plane is substantially located at half the length of the collimation section, which refers to the The distance between the light splitting surface and the joint surface is equal to the distance between the light splitting surface and the junction of the collimating section and the focusing section, or the distance between the light splitting surface and the joining surface is equal to the distance between the light splitting surface and the collimator The difference between the distance between the straight segment and the intersection of the focused segment is within 15%. The common optical path interference probe as described in claim 1, wherein the reference light passes through the collimation section and then is emitted to the reflective surface as a parallel collimated light ray, and then is reflected by the reflective surface and emitted back to the light splitting surface. , and finally focused on the light receiving and transmitting end surface through the reflection of the light splitting surface and the convergence of the collimating section; wherein, the sampling light is focused on the sample through the self-focusing lens component, and then is reflected by the sample and passes back through the The self-focusing lens component penetrates the light splitting surface and focuses on the light transmitting and receiving end surface. The common optical path interference probe as described in claim 1, wherein the optical path of the light beam traveling through the light conductive element is substantially equal to the optical path of the sampling light traveling from the junction of the collimating section and the focusing section to the sample, Wherein, the optical path of the light beam traveling through the light conductive element is substantially equal to the optical path of the sampling light traveling from the junction of the collimating section and the focusing section to the sample, which means that the light beam travels through the light conductive element. The optical path of the sampled light from the collimator section to the condenser The difference between the optical path from the junction of the focal lengths to the sample is less than the optical path between the common optical path interference probe and the sample by two orders of magnitude. The common optical path interference probe as claimed in claim 1, wherein the optical transceiver end face of the optical fiber is connected to the proximal axis of the first connection end face of the light conductive element, and the reflective surface is located off-axis of the first connection end face. And it is an annular reflective surface, and the reflective surface surrounds the light transmitting and receiving end surface. The common optical path interference probe according to claim 1 further includes a protective glass, wherein the protective glass is disposed between the self-focusing lens component and the sample. The common optical path interference probe as claimed in claim 1 further includes an optical turning element disposed between the self-focusing lens component and the sample, wherein the optical turning element is suitable for turning the sampling light. The common optical path interference probe as claimed in claim 1, wherein the self-focusing lens component includes a first self-focusing lens and a second self-focusing lens that are coaxially arranged and connected, and the second self-focusing lens is smaller than the first self-focusing lens. The lens is far away from the light transmission element, the joint surface is located on the side of the first self-focusing lens away from the second self-focusing lens, there is a connection surface between the first self-focusing lens and the second self-focusing lens, and the The light splitting surface is provided on the connection surface; wherein, the second self-focusing lens includes a first section and a second section connected to each other. The first section is connected to the first self-focusing lens, and the first section is connected to the first self-focusing lens. The lengths of the self-focusing lenses in the axial direction are substantially equal and together constitute the collimation section, Wherein, the length of the first section and the first self-focusing lens in the axial direction is substantially equal, which means that the length of the first section and the first self-focusing lens in the axial direction is equal, or it means that the first section There is a difference within 15% from the length of the first self-focusing lens in the axial direction. The common optical path interference probe as claimed in claim 7, wherein the light splitting surface is formed by a coating coated on the entire connection surface, and the reflectance of the light splitting surface is between 4% and 50%. The common optical path interference probe according to claim 7, wherein the light splitting surface has a transmission area and a reflection area, the transmission area is located at least on the paraxial axis of the light splitting surface, and the reflection area is located on the off-axis of the light splitting surface ; Wherein, the part of the light beam that irradiates the reflective area will be reflected by the reflective area to form the reference light, and the other part of the light beam that irradiates the transmission area will penetrate the transmission area to form the sampling light. The common optical path interference probe as claimed in claim 9, wherein the reflection area of the light splitting surface is an annular reflection surface, and the reflection area surrounds the transmission area. The common optical path interference probe as claimed in claim 1, wherein the self-focusing lens component includes a wide-diameter part and a narrow-diameter part that are integrally formed, and the outer diameter of the wide-diameter part is larger than the outer diameter of the narrow-diameter part, and the narrow-diameter part The diameter part is farther from the light conductive element than the wide diameter part, and the joint surface is located on a side of the wide diameter part away from the narrow diameter part. The narrow diameter part includes a connected front section and a rear section, and the front section is connected to the wide diameter part. part, the front part is the same as The lengths of the wide-diameter portion in the axial direction are substantially equal and together constitute the collimation section. The light-splitting surface has a transmission area and a reflection area, and the transmission area is located at a junction of the wide-diameter portion and the narrow-diameter portion, The wide-diameter portion has an annular surface surrounding the junction, and the reflection area is located on the annular surface; wherein, the portion of the light beam that irradiates the reflection area will be reflected by the reflection area to form the reference light, and irradiate the reference light. The other part of the transmission area, the light beam will penetrate the transmission area to form the sampling light, wherein the lengths of the front section and the wide diameter portion in the axial direction are substantially equal, which means that the length of the front section and the wide diameter portion are in the axial direction. The lengths in the axial direction are equal, or the difference between the lengths of the front section and the wide-diameter portion in the axial direction is within 15%. The common optical path interference probe as claimed in claim 1, further comprising a light turning element and a protective glass, wherein the light turning element is disposed between the self-focusing lens component and the sample, and the protective glass is disposed between the light turning element Between the sample and the light deflection element, the light deflection element is adapted to deflect the sampling light, and the protective glass is disposed between the self-focusing lens component and the sample. The common optical path interference probe as claimed in claim 12, wherein the optical path of the light beam traveling through the light conductive element is substantially equal to the optical path of the sampling light traveling through the focusing section, the sampling light traveling through the self-focusing lens component and the optical path. The sum of the optical path length of the air gap of the turning element, the optical path length of the sampling light traveling through the air gap between the light turning element and the protective glass, and the optical path length of the sampling light traveling through the air gap between the protective glass and the sample, Wherein, the optical path of the light beam traveling through the light conductive element is substantially equal to the optical path of the sampling light traveling through the focusing section, the optical path of the sampling light traveling through the air space between the self-focusing lens component and the light turning element, the The sum of the optical path of the sampling light traveling through the air gap between the light deflection element and the protective glass and the optical path of the sampling light traveling through the air gap between the protective glass and the sample refers to the light beam traveling through the light conductive element The optical path of the sampling light is the same as the optical path of the sampling light traveling through the focusing section, the optical path of the sampling light traveling through the air space between the self-focusing lens component and the light turning element, and the optical path of the sampling light traveling through the air between the light turning element and the protective glass. The difference between the optical path of the interval and the sum of the optical path of the sampling light traveling through the air gap between the protective glass and the sample is smaller than the optical path between the common optical path interference probe and the sample by two orders of magnitude.

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