Three-camera based multi-band image edge gray gradient focusing device and method

Abstract

The application discloses a three-camera-based multi-band image edge gray gradient focusing device and method, and relates to the field of focusing. The illumination module is used for emitting illumination light of complex color. The illumination light is projected onto a sample to be measured on an objective table through a microscope objective. Reflected light reflected by the sample to be measured enters the imaging module. The imaging module obtains images of different bands according to the reflected light. The image analysis and control module is connected with the illumination module and the imaging module. The image analysis and control module is used for extracting edge gradients of the images of different bands, determining defocusing distances of the corresponding bands according to the edge gradients of the images of different bands, determining the object distance between the microscope objective and the sample to be measured according to the defocusing distances of different bands, and moving the microscope objective to focus according to the object distance. The application can realize fast and high-precision automatic focusing.

Description

Technical Field

[0001] This invention relates to the field of focusing, and in particular to a multi-band image edge grayscale gradient focusing device and method based on three cameras. Background Technology

[0002] Micro-nano detection often requires extensive axial and horizontal scanning when measuring objects beyond the measurement range. During the scanning process, images frequently become out of focus due to unevenness of the object itself. Traditional manual focusing is time-consuming, inefficient, and fails to meet accuracy and stability requirements. Current autofocus methods generally require axial scanning to acquire a large number of images before use. During use, the acquired images are compared with images meeting the requirements, and axial movement is performed. When the difference is less than a threshold, autofocus is completed. However, this method also suffers from excessive time consumption.

[0003] Therefore, there is an urgent need for a fast autofocus device or method to solve the problems existing in the prior art. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-band image edge grayscale gradient focusing device and method based on three cameras, which can achieve fast and high-precision autofocus.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A multi-band image edge grayscale gradient focusing device based on three cameras includes: an illumination module, an imaging module, and an image analysis and control module;

[0007] The illumination module is used to emit polychromatic illumination light; the illumination light is projected onto the sample to be tested on the stage through the microscope objective, and the reflected light from the sample enters the imaging module; the imaging module obtains images of different wavelengths based on the reflected light.

[0008] The image analysis and control module is connected to the illumination module and the imaging module respectively. The image analysis and control module is used to extract the edge gradient of images in different bands, and determine the defocus distance of the corresponding band based on the edge gradient of the images in different bands. Then, it determines the object distance between the microscope objective and the sample to be tested based on the defocus distance of the different bands, and moves the microscope objective to focus according to the object distance.

[0009] Optionally, the lighting module includes: a polychromatic lighting source and a lens L1; the polychromatic lighting source is a polychromatic light source composed of monochromatic light with ≥3 wavelengths.

[0010] Optionally, the imaging module includes: a camera imaging unit, a beam splitter prism BS, a motor PI, a microscope objective, and a stage;

[0011] The illumination light is projected downwards through the beam splitter BS and onto the sample to be tested on the stage via the microscope objective; the reflected light from the sample then passes upwards through the beam splitter BS and enters the camera imaging unit.

[0012] Optionally, the camera imaging unit includes: 3 camera imaging subunits and 2 dichroic mirrors;

[0013] The first dichroic mirror reflects the reflected light to the first camera imaging subunit and the second dichroic mirror respectively; the second dichroic mirror reflects the reflected light to the second camera imaging subunit and the third camera imaging subunit respectively;

[0014] The camera imaging subunit performs imaging in the corresponding wavelength band based on the reflected light.

[0015] Optionally, each of the camera imaging subunits includes: a filter, a converging lens, and a monochrome camera.

[0016] Optionally, the black-and-white cameras in the three camera imaging subunits have the same camera target surface.

[0017] Optionally, the monochrome camera in the three camera imaging subunits is at the same distance from the converging lens.

[0018] A multi-band image edge gray-level gradient focusing method based on a three-camera system is applied to the aforementioned multi-band image edge gray-level gradient focusing device based on a three-camera system. The focusing method includes:

[0019] By illuminating a plane mirror with polychromatic light, and turning on the black and white additive phases respectively, the focal length of the corresponding band of the camera imaging subunit is calibrated.

[0020] The sample to be tested is placed on the stage, and images of the corresponding bands are acquired simultaneously using three camera imaging subunits.

[0021] Extract the edge gradients of images in different spectral bands, and determine the defocus distance of the corresponding spectral band based on the edge gradients of images in different spectral bands;

[0022] The distance between the microscope objective and the sample to be tested is determined based on the defocus distance of different wavelengths, and the microscope objective is moved to focus according to the distance.

[0023] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0024] This invention provides a multi-band image edge grayscale gradient focusing device and method based on a three-camera system. The imaging module obtains images of different bands based on reflected light. The image analysis and control module extracts the edge gradients of the images in different bands and determines the defocus distance for each band based on these gradients. Then, the object distance between the microscope objective and the sample is determined based on these defocus distances. The microscope objective is moved according to the object distance to achieve focusing. Rapid autofocus is achieved based on the multi-band image edge grayscale gradient. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a multi-band image edge grayscale gradient focusing device based on three cameras provided by the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The purpose of this invention is to provide a multi-band image edge grayscale gradient focusing device and method based on three cameras, which can achieve fast and high-precision autofocus.

[0029] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown, the present invention provides a multi-band image edge grayscale gradient focusing device based on three cameras, comprising: an illumination module, an imaging module, and an image analysis and control module;

[0031] The illumination module is used to emit polychromatic illumination light; the illumination light is projected onto the sample to be tested on the stage through the microscope objective, and the reflected light from the sample enters the imaging module; the imaging module obtains images of different wavelengths based on the reflected light.

[0032] The image analysis and control module is connected to the illumination module and the imaging module respectively. The image analysis and control module is used to extract the edge gradient of images in different bands, and determine the defocus distance of the corresponding band based on the edge gradient of the images in different bands. Then, it determines the object distance between the microscope objective and the sample to be tested based on the defocus distance of the different bands, and moves the microscope objective to focus according to the object distance.

[0033] The edges of a blurred image are determined using the formula i(x) = f(x) * g(x,σ);

[0034] Where i(x) is the blurred image, f(x) is the original image, and g(x,σ) is the point spread function of the microscope system;

[0035] Edge detection is performed using the Canny operator and the formula. Determine the image gradient; where, For horizontal gradient, This represents the vertical gradient.

[0036] Normalization is used to eliminate inconsistencies in gradient magnitude across different bands. Dividing the edge gradients of different channels yields:

[0037]

[0038] in, σ represents the image gradient of two different bands; j σ i It refers to the blurriness of images in different spectral bands;

[0039] At the center of the edge, according to the imaging formula: Determine the degree of ambiguity;

[0040] Where K is a constant, D is the lens diameter, s is the distance between the image plane and the system, and d f d is the focal distance, and d is the object distance. dj and di represent the distances from the focal plane to different wavelengths.

[0041] The lighting module includes: a polychromatic lighting source and a lens L1; the polychromatic lighting source is a polychromatic light source composed of monochromatic light with ≥3 wavelengths.

[0042] The imaging module includes: a camera imaging unit, a beam splitter prism BS, a motor PI, a microscope objective lens, and a stage.

[0043] The illumination light is projected downwards through the beam splitter BS and onto the sample to be tested on the stage via the microscope objective; the reflected light from the sample then passes upwards through the beam splitter BS and enters the camera imaging unit.

[0044] The camera imaging unit includes: 3 camera imaging sub-units and 2 dichroic mirrors;

[0045] The first dichroic mirror reflects the reflected light to the first camera imaging subunit and the second dichroic mirror respectively; the second dichroic mirror reflects the reflected light to the second camera imaging subunit and the third camera imaging subunit respectively;

[0046] The camera imaging subunit performs imaging in the corresponding wavelength band based on the reflected light.

[0047] Each of the camera imaging subunits includes a filter, a converging lens, and a monochrome camera. The filter allows light of the desired wavelength to pass through while filtering out other wavelengths; the converging lens focuses the light; and the monochrome camera forms the image. The filter is a narrowband filter.

[0048] The black-and-white cameras in the three camera imaging subunits have the same camera target surface.

[0049] The black-and-white camera in the three camera imaging subunits is at the same distance from the converging lens.

[0050] As a specific embodiment, the present invention also provides a multi-band image edge gray-scale gradient focusing method based on a three-camera system, applied to the aforementioned multi-band image edge gray-scale gradient focusing device based on a three-camera system. The focusing method includes:

[0051] S101 uses polychromatic illumination light to illuminate a plane mirror, turns on black and white additive separately, and calibrates the focal length of the corresponding band of the camera imaging subunit.

[0052] A plane mirror is illuminated with polychromatic light. One of the cameras is turned on to capture the axial intensity curve of a certain wavelength of light. The distance from the plane mirror at the start of the scan is recorded. The scan process involves defocusing, focusing, and then defocusing again. The focal length of this wavelength is the distance with the maximum light intensity value on the intensity curve. Subtracting the distance moved from the initial distance gives the focal length of this wavelength.

[0053] S102, the sample to be tested is placed on the stage, and the three camera imaging subunits are used to simultaneously acquire images of the corresponding bands;

[0054] S103, extract the edge gradient of images in different bands, and determine the defocus distance of the corresponding band based on the edge gradient of images in different bands;

[0055] S104 determines the object distance between the microscope objective and the sample to be tested based on the defocus distance of different wavelengths, and moves the microscope objective to focus according to the object distance.

[0056] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple; relevant parts can be referred to the method section.

[0057] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A three-camera-based multi-band image edge gray gradient focusing device, characterized in that, The application relates to a microscope focusing method and device. The device comprises an illumination module, an imaging module and an image analysis and control module. The illumination module is used for emitting illumination light of complex color light; the illumination light is projected onto a sample to be measured on an objective table through a microscope objective; reflected light reflected by the sample to be measured enters the imaging module; the imaging module obtains images of different wave bands according to the reflected light; The image analysis and control module is connected with the illumination module and the imaging module respectively; the image analysis and control module is used for extracting edge gradients of the images of different wave bands and determining defocusing distances of the corresponding wave bands according to the edge gradients of the images of different wave bands, and then determining an object distance between the microscope objective and the sample to be measured according to the defocusing distances of different wave bands and moving the microscope objective to focus according to the object distance. The illumination module comprises a complex color illumination light source and a lens L1; the complex color illumination light source is a complex color light source composed of single color light with a wave band number greater than or equal to 3. The imaging module comprises a camera imaging unit, a beam splitter BS, a motor PI, a microscope objective and an objective table. The illumination light is projected onto the sample to be measured on the objective table through the microscope objective downward through the beam splitter BS; and the reflected light reflected by the sample to be measured enters the camera imaging unit upward through the beam splitter BS. The camera imaging unit comprises three camera imaging subunits and two dichroic mirrors. The first dichroic mirror reflects the reflected light to the first camera imaging subunit and the second dichroic mirror respectively; the second dichroic mirror reflects the reflected light to the second camera imaging subunit and the third camera imaging subunit respectively. The camera imaging subunit performs imaging of the corresponding wave band according to the reflected light.

2. The multi-band image edge gray gradient focusing device based on three cameras according to claim 1, characterized in that, Each camera imaging subunit comprises a filter, a converging lens and a black-and-white camera.

3. The multi-band image edge gray gradient focusing device based on three cameras according to claim 2, characterized in that, The camera target surfaces of the black-and-white cameras in the three camera imaging subunits are the same.

4. The multi-band image edge gray gradient focusing device based on three cameras according to claim 2, characterized in that, The distances between the black-and-white cameras in the three camera imaging subunits and the converging lens are the same.

5. A three-camera-based multi-band image edge gray gradient focusing method, applied to the three-camera-based multi-band image edge gray gradient focusing device of any one of claims 1-4, characterized in that, The focusing method comprises the following steps: The illumination light of the complex color light is irradiated on a plane mirror, the black-and-white cameras are turned on respectively, and the focal distances of the corresponding wave bands of the corresponding camera imaging subunits are calibrated; The sample to be measured is placed on the objective table, and the corresponding wave band images are acquired by the three camera imaging subunits simultaneously; The edge gradients of the images of different wave bands are extracted, and the defocusing distances of the corresponding wave bands are determined according to the edge gradients of the images of different wave bands; The object distance between the microscope objective and the sample to be measured is determined according to the defocusing distances of different wave bands, and the microscope objective is moved to focus according to the object distance.

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