Working distance calibration device and calibration method of microscopic system

Abstract

The invention provides a working distance calibration device and method of a microscopic system, the working distance calibration device of the microscopic system comprises an objective lens, an optical flat plate and a barrel lens which are arranged in sequence, and a reference object can be calibrated on an ideal working distance of the objective lens through the working distance calibration device of the microscopic system. According to the working distance calibration method of the microscopic system, an optical signal emitted by a reference object sequentially passes through an objective lens, an optical flat plate and a barrel lens, the barrel lens can respectively form a first optical image and a second optical image because the optical signal is subjected to two different treatments in the optical flat plate, and the working distance between the reference object and the objective lens can be calibrated by adjusting the working distance between the reference object and the objective lens. The distance between the first optical image and the second optical image reaches an ideal error, and finally the reference object is located on the ideal working distance of the objective lens. The working distance calibration device of the microscopic system and the working distance calibration method of the microscopic system have the advantages of being high in precision, wide in application range, simple in structure and convenient to operate.

Description

Technical Field

[0001] The invention relates to the field of optical device debugging, and in particular to a working distance calibration device and a working distance calibration method for a microscope system. Background Art

[0002] In the microscopic imaging system, the working distance calibration of the microscope objective is very important, which not only affects important indicators such as the imaging quality, distortion, and telecentricity of the objective, but also affects the compatibility of the objective with other optical modules. The microscope objective is usually an infinity correction system. When the image plane of the reference object is located at the ideal working distance of the objective, the light beam emitted by the reference object is collimated by the objective. Therefore, the light beam emitted by the reference object can be collimated by the objective to determine whether the image plane of the reference object is located at the ideal working distance of the objective.

[0003] Existing working distance calibration methods include interference method, wavefront beam splitting test method, and infinite imaging method. Among them, the interference method is to interfere the light beam emitted by the reference object with the reference light or its sheared light, and the distribution of interference fringes is used to test the collimation of the light beam. The interference method has high inspection accuracy, but the interference method requires the light source to have monochromaticity and low expansibility and the operation is relatively complicated. The wavefront beam splitting test method is to test the collimation of the light beam by the distribution of image points on the image plane after the light beam is split according to different apertures and imaged. The wavefront fractional test method has high accuracy for monochromatic point light sources, but the method has a complex structure and is difficult to implement. The infinite imaging method is based on the reversible principle of the optical path. The reference object is placed at infinity on the object side of the image plane, and the objective lens is imaged to its object side focal plane. At this time, the reference object image plane is located at the ideal working distance of the objective lens, but the implementation conditions of this method are limited.

[0004] Therefore, how to design a working distance calibration device and a working distance calibration method for a microscope system that has a wide range of applications and is easy to operate has become one of the problems that technical personnel in this field need to solve urgently.

[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present invention and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because these solutions are described in the background technology section of the present invention. Summary of the invention

[0006] In view of the shortcomings of the prior art mentioned above, an object of the present invention is to provide a working distance calibration device for a microscope system and a working distance calibration method for a microscope system, so as to solve the problem in the prior art that it is difficult to design a working distance calibration device for a microscope system and a working distance calibration method for a microscope system with a wide range of applications and easy operation.

[0007] To achieve the above-mentioned purpose and other related purposes, the present invention provides a working distance calibration device for a microscope system, the working distance calibration device for a microscope system at least comprising: an objective lens, an optical plate and a tube lens; the objective lens receives a light signal emitted by a reference object and transmits the light signal to the optical plate; the optical plate is arranged between the objective lens and the tube lens, so that the light signal output by the objective lens produces an optical path difference and outputs a first light signal and a second light signal respectively; the tube lens receives the first light signal and converges it into a first optical image, and receives the second light signal and converges it into a second optical image; the center of curvature of the tube lens and the center of curvature of the objective lens are both on the optical axis.

[0008] Optionally, the working distance calibration device of the microscope system further includes an imaging device, which is disposed on the focal plane of the tube lens and is used to develop the first optical image and the second optical image.

[0009] Optionally, the optical plate is a parallel plate or a wedge-shaped plate.

[0010] Optionally, the optical flat plate is placed tilted relative to the optical axis, wherein the angle between the normal line of the incident surface of the optical flat plate and the optical axis is θ, and the value of θ ranges from 30 degrees to 60 degrees.

[0011] To achieve the above-mentioned purpose and other related purposes, the present invention also provides a working distance calibration method for a microscope system, which is implemented based on the working distance calibration device of the microscope system. The working distance calibration method of the microscope system at least includes:

[0012] S1: The light signal emitted by the reference object is transmitted to the optical plate via the objective lens; the light signal output by the objective lens generates a first light signal and a second light signal having an optical path difference via the optical plate, and the first light signal and the second light signal are output to the tube lens; the first light signal is converged into a first optical image via the tube lens, and the second light signal is converged into a second optical image via the tube lens;

[0013] S2: In the direction of the optical axis, change the distance between the reference object and the objective lens so that the real image distance is reduced until the real image distance is within the ideal error, thereby making the reference object at the ideal working distance of the objective lens; the real image distance is the distance between the projection of the center of the first optical image along the optical axis to the focal plane of the tube lens and the projection of the center of the second optical image along the optical axis to the focal plane of the tube lens, or the real image distance is the distance between the projection of the center of the first optical image along the optical axis to the plane parallel to the focal plane of the tube lens and the projection of the center of the second optical image along the optical axis to the plane parallel to the focal plane of the tube lens.

[0014] Optionally, when the distance between the reference object and the objective lens is changed in the direction of the optical axis, the position of the imaging device is adjusted to develop the first optical image and the second optical image to determine the real image distance.

[0015] Optionally, the optical signal is refracted by the incident surface of the optical plate and then refracted by the exit surface of the optical plate to generate the first optical signal; the optical signal is refracted by the incident surface of the optical plate, reflected by the exit surface, reflected by the incident surface and then refracted by the exit surface to generate the second optical signal.

[0016] Optionally, the calculation formula of the real image distance is as follows:

[0017]

[0018] Among them, f is the focal length of the tube lens; l is the average value of the first vertical distance and the second vertical distance, the first vertical distance is the distance from the first virtual image to the plane where the tube lens is located along the optical axis, the second vertical distance is the distance from the second virtual image to the plane where the tube lens is located along the optical axis, the first virtual image is formed by the intersection of the reverse extension line of the first light signal, and the second virtual image is formed by the intersection of the reverse extension line of the second light signal; t is the thickness of the optical plate; θ is the angle between the optical axis and the incident normal of the incident surface of the optical plate; n is the refractive index of the optical plate; α is the angle between the incident surface and the exit surface in the optical plate.

[0019] More optionally, before step S1, the optical plate is rotated to change the value of θ, and the range of the value of θ is 30 degrees to 60 degrees, so as to improve the numerical accuracy of the real image distance.

[0020] As described above, the working distance calibration device and working distance calibration method of a microscope system of the present invention have the following beneficial effects:

[0021] 1. The present invention arranges an optical flat plate so that the reference object forms a first optical image and a second optical image respectively. By changing the working distance between the reference object and the objective lens, the present invention can make the real image distance within an ideal error, that is, the light signal emitted by the reference object is collimated by the objective lens, and the reference object is located at the ideal working distance of the objective lens.

[0022] 2. The present invention can improve the numerical accuracy of the real image distance by changing the angle between the optical axis and the optical flat plate incident method, thereby improving the numerical accuracy of the ideal working distance.

[0023] 3. The working distance calibration device of a microscope system and the working distance calibration method of a microscope system of the present invention have the advantages of high accuracy, wide application range, simple structure and convenient operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a schematic structural diagram of a working distance calibration device for a microscope system of the present invention.

[0025] Figure 2 It is a schematic diagram showing a first structure of the optical flat plate of the present invention.

[0026] Figure 3 It is a schematic diagram showing a second structure of the optical flat plate of the present invention.

[0027] Figure 4 It is a schematic diagram showing the angle between the optical axis and the incident normal line of the incident surface of the optical flat plate according to the present invention.

[0028] Figure 5 Shown is a schematic diagram of the real image distance of the present invention.

[0029] Figure 6 Shown is a schematic flow chart of a working distance calibration method for a microscope system of the present invention.

[0030] Figure 7 It is a schematic diagram showing the transmission of the optical signal in the optical flat plate of the present invention.

[0031] Figure 8 It is a schematic diagram showing the first vertical distance and the second vertical distance of the present invention.

[0032] Component number description

[0033] 1 Objective lens

[0034] 2 Optical Plate

[0035] 2a Incident surface

[0036] 2b Exit surface

[0037] 3 Tube mirror

[0038] A Reference

[0039] M First optical image

[0040] N Second optical image

[0041] P first virtual image

[0042] Q second virtual image

[0043] l1 First vertical distance

[0044] l2 Second vertical distance

[0045] M' Projection of the first optical image

[0046] N' Projection of the second optical image

[0047] d Real image distance DETAILED DESCRIPTION

[0048] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0049] See also Figure 1-Figure 8 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0050] Embodiment 1

[0051] like Figure 1 As shown, this embodiment provides a working distance calibration device for a microscope system, and the working distance calibration device for a microscope system includes: an objective lens 1, an optical flat plate 2 and a tube lens 3.

[0052] like Figure 1 As shown, the objective lens 1 receives the optical signal emitted by the reference object A and transmits the optical signal to the optical plate 2 .

[0053] Specifically, in this embodiment, the light signal emitted by reference object A can be generated by reference object A itself, or it can be a light signal reflected or refracted by reference object A; the light signal is transmitted to objective lens 1, which refers to the objective lens in the microscope system, and when reference object A is placed at the ideal working distance of the objective lens, objective lens 1 can collimate the light signal emitted by reference object A.

[0054] like Figure 1 As shown, the optical flat plate 2 is disposed between the objective lens 1 and the tube lens 3, so that the optical signal output by the objective lens 1 generates an optical path difference and outputs a first optical signal and a second optical signal respectively.

[0055] Specifically, in this embodiment, the optical plate 2 refers to a transparent plate commonly used in the field of physical optics, and both the incident surface 2a and the exit surface 2b of the optical plate 2 are precisely polished; as an example, Figure 2 and Figure 3 As shown, the optical plate 2 is a parallel plate or a wedge-shaped plate. In practical applications, the specific type of the optical plate 2 is selected according to actual needs and is not limited to this embodiment.

[0056] Specifically, in this embodiment, the optical plate 2 is placed obliquely relative to the optical axis (the oblique placement means that the angle between the incident normal line of the incident surface of the optical plate and the optical axis is not zero), wherein: Figure 4 As shown, the angle between the optical axis and the normal of the incident surface 2a of the optical plate is θ, and the value of θ ranges from 30 degrees to 60 degrees, including but not limited to 35 degrees, 40 degrees, 45 degrees, 50 degrees, and 55 degrees; the purpose of tilting the optical plate 2 is to change the value of θ so that the accuracy of the real image distance d is improved.

[0057] like Figure 1 As shown, the tube lens 3 receives the first light signal and converges it into a first optical image M, and receives the second light signal and converges it into a second optical image N; the curvature center of the tube lens 3 and the curvature center of the objective lens 1 are both on the optical axis.

[0058] Specifically, in the present embodiment, the tube lens 3 has a focusing function, the tube lens 3 and the objective lens 1 are usually used in conjunction with each other in a microscope system, the tube lens 3 and the objective lens 1 are arranged in parallel, and the centers of curvature of the tube lens 3 and the objective lens 1 are both on the optical axis; the distance between the projection of the first optical image M along the optical axis direction to the focal plane of the tube lens (or a plane parallel to the focal plane of the tube lens) and the projection of the second optical image N along the optical axis direction to the focal plane of the tube lens (or a plane parallel to the focal plane of the tube lens) is the real image distance d, as Figure 5 As shown, the projection of the first optical image M is M', the projection of the second optical image N is N', M' and N' are located in the same plane, and the plane where M' and N' are located is the focal plane of the tube lens or a parallel plane of the focal plane of the tube lens, and the distance between the center of M' and the center of N' is the real image distance d. Further, by changing the position of the reference object A or the objective lens 1 in the optical axis direction, that is, adjusting the working distance between the reference object A and the objective lens 1, so that the real image distance d is within the ideal error, and then the reference object A is placed at the ideal working distance of the objective lens 1, it is considered that the working distance of the microscope system has been calibrated; further, after obtaining the ideal working distance between the reference object A and the objective lens 1, the optical plate 2 is withdrawn from the optical path, and the microscope system starts to work.

[0059] Specifically, in this embodiment, the working distance calibration device of the microscope system further includes an imaging device, which is arranged near the focal plane of the tube lens 3 and is used to clearly develop the first optical image M and the second optical image N. The imaging device can be used to accurately locate the positions of the projection M' of the first optical image M and the projection N' of the second optical image N to calculate the real image distance d. As an example, the imaging device can be an imaging camera, and the specific type of the imaging device is selected according to actual needs in actual applications, which is not limited to this embodiment.

[0060] Embodiment 2

[0061] like Figure 6As shown, this embodiment provides a working distance calibration method for a microscope system, which is implemented based on the working distance calibration device for a microscope system in Embodiment 1. The working distance calibration method for a microscope system includes the following steps:

[0062] like Figure 1 As shown, in step S1, the light signal emitted by the reference object A is transmitted to the optical plate 2 via the objective lens 1; the light signal output by the objective lens 1 generates a first light signal and a second light signal having an optical path difference via the optical plate 2, and the first light signal and the second light signal are output to the tube lens 3; the first light signal is converged into a first optical image M via the tube lens 3, and the second light signal is converged into a second optical image N via the tube lens 3.

[0063] Specifically, in this embodiment, when the real image distance d between the projection M' of the first optical image M and the projection N' of the second optical image is within the ideal error, the light signal output by the objective lens can be considered to be collimated, and at this time, the distance between the reference object A and the objective lens 1 in the optical axis direction is the ideal working distance. Based on this, this embodiment can achieve the calibration of the working distance of the microscope system. As an example, when the optical plate is a parallel plate, the ideal value of the real image distance is 0, and when the optical plate is a wedge-shaped plate, the ideal value of the real image distance depends on the type of the wedge-shaped plate; in common cameras, whether the optical plate is a parallel plate or a wedge-shaped plate, the real image distance is within 0.1 pixels of the ideal value of the real image distance and can be considered to be within the ideal error. In practical applications, the range of the ideal error is set as needed, and is not limited to this embodiment.

[0064] Specifically, in this embodiment, the optical plate 2 includes an incident surface 2a and an exit surface 2b, and the optical signal output by the objective lens 1 generates a first optical signal and a second optical signal having an optical path difference through two different transmission paths in the optical plate 2; as an example, Figure 1 As shown, the optical signal is refracted by the incident surface 2a of the optical plate 2 and then refracted by the exit surface 2b of the optical plate 2 to generate the first optical signal; the optical signal is refracted by the incident surface 2a of the optical plate 2, reflected by the exit surface 2b, reflected by the incident surface 2a and then refracted by the exit surface 2b to generate the second optical signal, and according to the law of reflection, as Figure 7 As shown, the incident angle of the light signal at the first reflection on the exit surface 2b is equal to the reflection angle, and the incident angle of the light signal at the second reflection on the incident surface 2a is also equal to the reflection angle.

[0065] like Figure 1As shown, in step S2, in the direction of the optical axis, the distance between the reference object A and the objective lens 1 is changed so that the real image distance d is reduced until the real image distance d is within the ideal error, thereby making the reference object A at the ideal working distance of the objective lens 1; the real image distance d is the distance between the projection of the center of the first optical image M along the optical axis to the focal plane of the tube lens and the projection of the center of the second optical image N along the optical axis to the focal plane of the tube lens, or the real image distance d is the distance between the projection of the center of the first optical image M along the optical axis to the plane parallel to the focal plane of the tube lens and the projection of the center of the second optical image N along the optical axis to the plane parallel to the focal plane of the tube lens.

[0066] Specifically, in this embodiment, the first optical image center and the second optical image center refer to the geometric centers of the first optical image M and the second optical image N, and the projection of the first optical image and the projection of the second optical image are in the same plane; further, the calculation formula of the real image distance d is as follows:

[0067]

[0068] Specifically, in this embodiment, f represents the focal length of the tube lens 3. l represents the average value of the first vertical distance l1 and the second vertical distance l2, l1 (such as Figure 8 As shown) is the distance from the first virtual image P along the optical axis to the plane where the tube lens 3 is located, l2 (as shown Figure 8 ) is the distance from the second virtual image Q to the plane where the tube lens 3 is located along the optical axis direction. The reverse extended dashed lines of the first light signal converge to form the first virtual image P, and the reverse extended dashed lines of the second light signal converge to form the second virtual image Q. n represents the refractive index of the optical plate 2. t represents the thickness of the optical plate 2. When the optical plate 2 is a wedge-shaped plate, t is the thickness at the geometric center of the incident surface of the wedge-shaped plate. α represents the angle between the incident surface 2a and the exit surface 2b of the optical plate 2. When the optical plate 2 is a parallel plate, α is 0 degrees. When the optical plate 2 is a wedge-shaped plate, as shown in FIG. Figure 3 As shown, α is usually an acute angle. θ represents the angle between the optical axis and the incident normal line of the incident surface 2a of the optical flat plate.

[0069] Specifically, in this embodiment, before step S1, the optical plate 2 is further rotated to change the value of θ, so as to improve the numerical accuracy of the real image distance d; a plane passing through the geometric center of the incident surface of the optical plate and with the optical axis as the normal is used as a rotation reference plane, and the optical plate 2 is rotated around any straight line passing through the geometric center of the optical plate in the rotation reference plane, and the value of θ changes, so that the numerical accuracy of the real image distance d is changed, and the range of θ is 30 degrees to 60 degrees, including but not limited to 35 degrees, 40 degrees, 45 degrees, 50 degrees, and 55 degrees.

[0070] Specifically, in the present embodiment, the position of the reference object A or the objective lens 1 in the optical axis direction is changed to change the working distance between the reference object A and the objective lens 1 in the optical axis direction, and the position of the imaging device is adjusted to make the first optical image M and the second optical image N clearly develop, so as to determine the real image distance. As an example, when the working distance increases, the position of the imaging device is adjusted to make the first optical image M and the second optical image N clearly develop on the imaging device, and the real image distance d is calculated. If the real image distance d decreases, the working distance is continued to increase, and the position of the imaging device is adjusted accordingly to make the first optical image M and the second optical image N clearly develop until the real image distance d is within the ideal error; or when the working distance increases, the position of the imaging device is adjusted to make the first optical image M and the second optical image N clearly develop on the imaging device, and the real image distance d is calculated. If the real image distance d increases, the working distance is adjusted to decrease, and the position of the imaging device is adjusted accordingly to make the first optical image M and the second optical image N clearly develop until the real image distance d is within the ideal error. The step of adjusting the real image distance d to the ideal error when the working distance decreases is similar to that when the working distance increases, and will not be repeated here.

[0071] In summary, the present invention has no specific requirements for the light signal emitted by the reference object. The present invention sets an optical plate between the objective lens and the tube lens, and uses the optical plate to make the light signal produce an optical path difference in the optical plate. The present invention can form a first optical image and a second optical image, calculate the distance between the projections of the first optical image and the second optical image on the tube lens focal plane (or the parallel plane of the tube lens focal plane) along the optical axis direction, and change the working distance between the reference object and the objective lens so that the real image distance is within the ideal error. The present invention can finally set the reference object at the ideal working distance of the objective lens, that is, the present invention can complete the calibration of the working distance of the microscope system. In addition, the present invention also has the advantages of wide application range, simple structure and convenient operation. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has a high industrial utilization value.

[0072] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A working distance calibration device for a microscope system, characterized in that: The working distance calibration device of the microscope system at least comprises: an objective lens, an optical flat plate and a tube lens; The objective lens receives the optical signal emitted by the reference object and transmits the optical signal to the optical flat plate; The optical flat plate is arranged between the objective lens and the tube lens, so that the optical signal output by the objective lens generates an optical path difference and outputs a first optical signal and a second optical signal respectively; The tube lens receives the first light signal and converges it into a first optical image, and receives the second light signal and converges it into a second optical image; the curvature center of the tube lens and the curvature center of the objective lens are both on the optical axis.

2. The working distance calibration device for a microscope system according to claim 1, characterized in that: The working distance calibration device of the microscope system further comprises an imaging device, and the imaging device is used to develop the first optical image and the second optical image.

3. The working distance calibration device for a microscope system according to claim 1, characterized in that: The optical plate is a parallel plate or a wedge-shaped plate.

4. The working distance calibration method of a microscope system according to any one of claims 1 to 3, characterized in that: The optical flat plate is placed obliquely relative to the optical axis, wherein the angle between the normal line of the incident surface of the optical flat plate and the optical axis is θ, and the value of θ ranges from 30 degrees to 60 degrees.

5. A method for calibrating the working distance of a microscope system, implemented based on the working distance calibration device of a microscope system according to any one of claims 1 to 4, characterized in that: The working distance calibration method of the microscope system at least comprises: S1: The light signal emitted by the reference object is transmitted to the optical plate via the objective lens; the light signal output by the objective lens generates a first light signal and a second light signal having an optical path difference via the optical plate, and the first light signal and the second light signal are output to the tube lens; the first light signal is converged into a first optical image via the tube lens, and the second light signal is converged into a second optical image via the tube lens; S2: In the direction of the optical axis, change the distance between the reference object and the objective lens so that the real image distance is reduced until the real image distance is within the ideal error, thereby making the reference object at the ideal working distance of the objective lens; the real image distance is the distance between the projection of the center of the first optical image along the optical axis to the focal plane of the tube lens and the projection of the center of the second optical image along the optical axis to the focal plane of the tube lens, or the real image distance is the distance between the projection of the center of the first optical image along the optical axis to the plane parallel to the focal plane of the tube lens and the projection of the center of the second optical image along the optical axis to the plane parallel to the focal plane of the tube lens.

6. The working distance calibration method of a microscope system according to claim 5, characterized in that: When the distance between the reference object and the objective lens is changed in the optical axis direction, the position of the imaging device is adjusted to develop the first optical image and the second optical image to determine the real image distance.

7. The working distance calibration method of a microscope system according to claim 5, characterized in that: The optical signal is refracted by the incident surface of the optical plate and then refracted by the exit surface of the optical plate to generate the first optical signal; the optical signal is refracted by the incident surface of the optical plate, reflected by the exit surface, reflected by the incident surface and then refracted by the exit surface to generate the second optical signal.

8. The working distance calibration method of a microscope system according to any one of claims 5 to 7, characterized in that: The calculation formula of the real image distance is as follows: Wherein, f is the focal length of the tube lens; l is the average value of the first vertical distance and the second vertical distance, the first vertical distance is the distance from the first virtual image along the optical axis to the plane where the tube lens is located, the second vertical distance is the distance from the second virtual image along the optical axis to the plane where the tube lens is located, the first virtual image is formed by the intersection of the reverse extension line of the first light signal, and the second virtual image is formed by the intersection of the reverse extension line of the second light signal; t is the thickness of the optical plate; θ is the angle between the optical axis and the incident normal line of the incident surface of the optical plate; n is the refractive index of the optical plate; α is the angle between the incident surface and the exit surface of the optical flat plate.

9. The working distance calibration method of a microscope system according to claim 8, characterized in that: Before step S1, the optical plate is rotated to change the value of θ, and the range of the value of θ is 30 degrees to 60 degrees, so as to improve the numerical accuracy of the real image distance.

Images