Binocular Endoscopic Detection System with Variable Depth of Field

Abstract

A binocular endoscope detection system with variable depth of field relates to the field of endoscope technology, and solves the problems of high cost, large size, and inability to clearly image a large depth-of-field range in the existing binocular endoscope detection system. The system mainly includes a plane mirror, an endoscope optical component, a deformable mirror group, an imaging lens, and a detector. The light reflected by the object to be measured is first refracted by the plane mirror, then transmitted backward through the endoscope optical component, collimated by the deformable mirror group, and finally converged onto the photosensitive surface of the detector through the imaging lens. This endoscope detection system can reduce the cost of the binocular endoscope, reduce the size of the binocular endoscope, and the depth-of-field range of the binocular endoscope detection system of the present invention can be changed to achieve clear imaging in a large depth-of-field range, improving the application range of endoscope detection.

Description

Technical Field

[0001] The present invention relates to the technical field of endoscopes, and particularly relates to a binocular endoscope detection system with variable depth of field. Background Art

[0002] The endoscope detection system is one of the main tools for non-destructive testing at present, and is mainly used in industrial fields such as aerospace, shipbuilding, automobile maintenance and production for damage detection. Especially in the aerospace field, the endoscope can detect the internal condition of the engine through a narrow channel without disassembling the aircraft, which not only saves the time and cost of detection, but also avoids damage to parts, and has high application value.

[0003] The binocular endoscope detection system not only has the advantages of the traditional endoscope detection system, but also has richer image information. According to the binocular stereo vision principle, it obtains endoscope images from two different angles, and then obtains the size and depth information of the object to be measured through image processing. There are many kinds of endoscope systems that can achieve binocular stereo detection, such as patents US522482, CN104656242 and CN110840385. The light beams are converged by two side-by-side optical systems and transmitted to the detector. There are two optical paths in their endoscope detection systems, and the size is doubled compared with the single-optical-path endoscope detection system, which cannot meet the requirements of endoscope detection in a narrow channel; although patent CN104107026 only uses a single optical path to transmit light, in order to achieve the binocular detection function, a beam splitting prism is placed at the exit end of the endoscope optical element to split the two beams of light and image them on their respective detectors. The two image sensors of this system increase the detection cost and also increase the size of the system. Moreover, the depth of field of the current binocular endoscope detection system is fixed, and it can only image a specific range of scenes, so the universality of use is low. Summary of the Invention

[0004] In order to solve the problems of high cost, large size and inability to clearly image a large depth of field range in the existing binocular endoscope detection system, the present invention proposes a binocular endoscope detection system with variable depth of field.

[0005] The binocular endoscope detection system with variable depth of field includes a plane mirror, an endoscope optical assembly, a deformable mirror group, an imaging mirror and a detector; the light reflected by the object to be measured first passes through the plane mirror for folding, and then passes through the endoscope optical assembly and is transmitted backward, collimated by the deformable mirror group, and finally converged onto the photosensitive surface of the detector through the imaging mirror;

[0006] The plane mirror can be translated along the optical axis direction of the endoscope assembly and rotated perpendicular to the optical axis direction through a control circuit, and a binocular stereo image pair can be obtained by imaging the plane mirror at two different positions or rotation angles;

[0007] The radius of curvature of the deformable mirror group is defaulted to infinity. When the object to be measured is within the depth of field of the binocular endoscope detection system, the light passing through the endoscope optical component is approximately parallel light. Keeping the radius of curvature infinite, the light passing through the deformable mirror group only changes the propagation direction and does not change the converging and diverging states. Then, a clear image is obtained on the detector through the imaging lens.

[0008] When the plane mirror is translated to achieve the binocular detection function, the rotation angles of the plane mirrors for the two images are unchanged, but they are in different positions. They are equivalent to binocular stereo vision with parallel optical axes, but they are offset by a certain distance along the optical axis, and the distances of the object to be measured at the two imaging positions from the endoscope optical component are different. To achieve the binocular stereo imaging function, the target point should be included in both images. Therefore, the mirror interval when the plane mirror is translated cannot be too far, that is, when the plane mirror is in two positions, the object to be measured should be within the overlapping range of the system field of view angle;

[0009] The movement of the plane mirror may cause one imaging position or both imaging positions to be outside the depth of field. Relying only on the imaging lens cannot guarantee the image quality on the detector. To obtain a clear image outside the depth of field, the deformation of the deformable mirror group needs to be adjusted at this time. When the distance between the object to be measured and the binocular endoscope detection system is less than the near-field depth, the radius of curvature of the first deformable mirror is adjusted by the control circuit to make it a concave mirror, and at the same time, the radius of curvature of the second deformable mirror is adjusted to make it a convex mirror, and the light passing through the endoscope optical component is adjusted to parallel light, and this parallel light passes through the imaging lens to obtain a clear image on the detector; when the distance between the object to be measured and the binocular endoscope detection system is greater than the far-field depth, the light passing through the endoscope optical component is converging light, then the radius of curvature of the first deformable mirror is adjusted by the control circuit to make it a convex mirror, and at the same time, the radius of curvature of the second deformable mirror is adjusted to make it a concave mirror, and the light passing through the endoscope optical component is adjusted to parallel light, and this parallel light passes through the imaging lens to obtain a clear image on the detector.

[0010] When the plane mirror is rotated to achieve the binocular detection function, the plane mirrors for the two images are in the same position but at different rotation angles. They are equivalent to binocular stereo vision with converging optical axes. Similarly, to achieve the binocular stereo imaging function, the target point should be included in both images. Therefore, the rotation angles when the plane mirror is rotated cannot differ too much, that is, when the plane mirror is at two rotation angles, the object to be measured should be within the overlapping range of the system field of view angle;

[0011] Since the position remains unchanged when the planar mirror is rotated, only the rotation angle is changed, so the imaging quality of the two times is similar. That is, if the first imaging is within the depth of field, the second imaging is also within the depth of field; if the first imaging is outside the depth of field, the second imaging is also outside the depth of field. To ensure that the object to be measured forms a clear image outside the depth of field, it is necessary to adjust the deformation of the deformable mirror group. When the distance between the object to be measured and the binocular endoscope detection system is less than the near scene depth, the curvature radius of the first deformable mirror is adjusted by the control circuit to make it a concave mirror, and the curvature radius of the second deformable mirror is adjusted to make it a convex mirror, so as to adjust the light passing through the endoscope optical component into parallel light, and this parallel light passes through the imaging mirror to obtain a clear image on the detector; when the distance between the object to be measured and the binocular endoscope detection system is greater than the far scene depth, the curvature radius of the first deformable mirror is adjusted by the control circuit to make it a convex mirror, and at the same time, the curvature radius of the second deformable mirror is adjusted to make it a concave mirror, so as to adjust the light passing through the endoscope optical component into parallel light, and this parallel light passes through the imaging mirror to obtain a clear image on the detector.

[0012] The beneficial effects of the present invention: The endoscope detection system described in the present invention includes a single optical system and a single detector, realizes the binocular stereoscopic vision function by changing the position or rotation angle of the planar mirror, and adjusts the depth of field of the overall system by controlling the deformation of the deformable mirror group, so that the object to be measured can achieve high-definition imaging in a large range of scene spaces, and solves the problems in the above background technology. It has the following advantages:

[0013] 1. Reduces the cost of the binocular endoscope and reduces the size of the binocular endoscope.

[0014] 2. The depth of field range of the binocular endoscope detection system can be changed, realizing clear imaging in a large depth of field range, and improving the application range of the endoscope.

[0015] 3. The overall system is simple to assemble and has strong practicability. Description of the Drawings

[0016] Figure 1 It is a schematic structural diagram of a binocular endoscope detection system with variable depth of field according to the present invention.

[0017] Figure 2 It is a binocular vision equivalent schematic diagram of the object to be measured for the translation planar mirror in the present invention.

[0018] Figure 3 It is a relationship diagram of the mirror spacing and the length of the object to be measured when the planar mirror is translated in the present invention.

[0019] Figure 4 It is a schematic diagram of the light propagation when the object to be measured is within the depth of field of the system in the present invention.

[0020] Figure 5 This is a schematic diagram of depth of field adjustment when the object to be measured in the present invention is at a distance less than the near - scene depth from the system.

[0021] Figure 6 This is a schematic diagram of depth of field adjustment when the object to be measured in the present invention is at a distance greater than the far - scene depth from the system.

[0022] Figure 7 These are two schematic diagrams for obtaining images when the plane mirror is translated.

[0023] Figure 8 This is a binocular vision equivalent schematic diagram of the object to be measured when the plane mirror rotates in the present invention.

[0024] Figure 9 This is a diagram showing the relationship between the mirror angle and the length of the object to be measured when the plane mirror rotates in the present invention.

[0025] Figure 10 These are two schematic diagrams for obtaining images when the plane mirror rotates. Specific implementation manners

[0026] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners. It should be understood that the specific implementation manners described herein are only used to explain the present invention and do not constitute a limitation to the present invention.

[0027] Combined with Figures 1 to 10 Describe this implementation manner. A binocular endoscope detection system with variable depth of field, as Figure 1 shown, this system mainly includes: a plane mirror 1, which is located at the very front of the overall system and can be moved along the optical axis direction or rotated along the direction perpendicular to the optical axis through a control circuit; an endoscope optical assembly 2 includes an objective lens 21, a steering mirror group 22 and an eyepiece 23 arranged in sequence along the optical axis to realize the transmission of light in a narrow channel; a deformable mirror group 3 includes a first deformable mirror 31 and a second deformable mirror 32, and the depth of field range of the overall system is changed by adjusting the radius of curvature of the deformable mirror group through a control circuit; finally, the light is converged onto a detector 5 through an imaging lens 4 to achieve high - definition imaging.

[0028] Figure 2This is the binocular vision equivalent schematic diagram of the translation plane mirror 1 in the present invention. The translation of the plane mirror is realized through a control circuit. This control circuit first converts the pulse signal of the voltage-controlled stepping motor into the rotation of the motor, and then converts the rotational motion into a linear displacement motion through a lead screw, thereby promoting the translation of the plane mirror 1. In the figure, θ is the field of view angle of the endoscope. When the light reflected by the object to be measured irradiates the plane mirror 1, the overall light path is equivalent to being flipped along the plane mirror 1. When the translation plane mirror 1 is at position 1 and position 2 respectively, a binocular stereo image pair is obtained through time-sharing imaging. At this time, they are equivalent to binocular stereo vision with parallel optical axes, but they are offset by a certain distance along the optical axis, and the distances between the object to be measured at the two imaging positions and the endoscope optical component are different. In order to achieve the binocular stereo imaging function, the point to be measured needs to be included in both images, that is, the object to be measured should be located within the overlapping range of the system field of view angle, that is Figure 2 the shaded part in

[0029] Figure 3 This is the relationship diagram between the mirror spacing and the length of the object to be measured when the plane mirror 1 is translated. In the figure, the plane mirror 1 forms a 45° angle with the optical axis. p1 and p2 are the positions of the plane mirror respectively, o1 and o2 are the system optical centers of the plane mirror 1 at p1 and p2 respectively, d is the interval between p1 and p2, l1 is the distance from p1 to o1, l2 is the vertical distance from the plane mirror to the object, h is the length of the object to be measured, and θ is the field of view angle. When the mirror interval is Δ, it just covers the entire object length h. At this time, the relationship between the mirror interval and the length of the object to be measured can be obtained as:

[0030]

[0031] The critical value Δ of the mirror interval of the plane mirror is obtained:

[0032]

[0033] Therefore, the mirror interval d of the plane mirror should not be greater than the critical value Δ, otherwise it cannot be guaranteed that the object to be measured can be imaged on the detector at both positions.

[0034] Figure 4 This is the schematic diagram of the light propagation when the object to be measured is within the system depth of field in the present invention. The radius of curvature of the first deformable mirror and the second deformable mirror are both defaulted to infinity. The light emitted from the endoscope optical component is approximately parallel light. At this time, keeping the radius of curvature infinite unchanged, the light passing through the deformable mirror group only changes the propagation direction and does not change the converging and diverging states. Then, a clear image is obtained on the detector through the imaging mirror.

[0035] When the translational plane mirror 1 realizes the binocular stereo function, since the movement of the plane mirror may cause the imaging position of a single time or the imaging positions of two times to be outside the depth of field range, relying solely on the imaging lens cannot guarantee the image quality on the detector. In order to obtain a clear image outside the depth of field range, at this time, it is necessary to adjust the deformation of the deformable mirror group. The deformation of the deformable mirror group is completed by the control circuit. The driver of this control circuit is composed of multiple drive units. Under the applied voltage, the MEMS driver is driven, and the curvature deformation of the overall deformable mirror is changed by driving the stroke of each unit. The depth of field adjustment schematic diagram when the object to be measured is less than the near-depth of the binocular endoscope detection system is as shown in Figure 5 shown. At this time, the light emitted from the endoscope optical component is no longer parallel light, but divergent light. If this light is not adjusted, a clear image cannot be formed on the detector after passing through the imaging lens. In this embodiment, the curvature radius of the first deformable mirror is adjusted by the control circuit to make it a concave mirror, and at the same time, the curvature radius of the second deformable mirror is adjusted to make it a convex mirror, so as to adjust the light passing through the endoscope optical component into parallel light. This parallel light passes through the imaging lens to obtain a clear image on the detector; the depth of field adjustment schematic diagram when the object to be measured is greater than the far-depth of the binocular endoscope detection system is as shown in Figure 6 shown. At this time, the light emitted from the endoscope optical component is no longer parallel light, but converging light. Then, by adjusting the curvature radius of the first deformable mirror to make it a convex mirror, and at the same time, adjusting the curvature radius of the second deformable mirror to make it a concave mirror, the light passing through the endoscope optical component is adjusted into parallel light. This parallel light passes through the imaging lens to obtain a clear image on the detector.

[0036] Figure 7 Schematic diagrams of obtaining two images when the plane mirror is translated. It can be seen from the figure that since the distance and position of the object to be measured from the endoscope optical component are different when the plane mirror is at position 1 and position 2, the imaging position and size are also different.

[0037] Figure 8 Schematic diagram of the binocular vision equivalence of the object to be measured when the plane mirror rotates in the present invention. The rotation of the plane mirror 1 is realized by the control circuit. This control circuit first converts the pulse signal of the stepping motor controlled by voltage into the rotation of the motor, and then realizes the rotation of the plane mirror through the worm and gear transmission and the rotating shaft. The optical path when passing through the plane mirror is equivalent to being reversed. When the plane mirror is rotated to rotation angle 1 and rotation angle 2 respectively, they are equivalent to binocular stereo vision with the optical axes converging. In order to realize the binocular stereo imaging function, it is also necessary to include the measurement point in both images, that is, the object to be measured should be located within the overlapping range of the system field of view angle, that is, Figure 7 the shaded part in.

[0038] Figure 9It is a diagram showing the relationship between the mirror angle and the length of the object to be measured when the planar mirror is rotated. o 1' and o 2' are the optical centers of the system at different rotation angles of the planar mirror respectively. They are in symmetric positions. p is the position of the planar mirror, ω is the rotation angle of the planar mirror 1, l 1' and l 2' are the perpendicular distances from the optical center to the planar mirror and from the planar mirror to the object to be measured respectively. h is the length of the object to be measured, and θ is the field of view angle. When the rotation angle of the mirror surface is ω', it just covers the entire object length h. The relationship between the rotation angle ω' of the mirror and the length h of the object to be measured can be obtained as follows:

[0039]

[0040] The angle value obtained at this time is the critical value ω'. The actual rotation angle ω of the planar mirror 1 should be less than the critical value ω', otherwise it cannot be guaranteed that the point to be measured can be imaged on the detector at both positions.

[0041] When the binocular stereo function is realized by rotating the planar mirror, since the position of the planar mirror remains unchanged during rotation and only the rotation angle is changed, the imaging quality of the two times is similar, that is, if the first imaging is within the depth of field, the second imaging is also within the depth of field; if the first imaging is outside the depth of field, the second imaging is also outside the depth of field. In order to ensure that the object to be measured forms a clear image outside the depth of field, it is necessary to adjust the deformation of the deformable mirror group. In this embodiment, when the distance between the object to be measured and the binocular endoscope detection system is less than the near - scene depth, the curvature radius of the first deformable mirror is adjusted by the control circuit to make it a concave mirror, and the curvature radius of the second deformable mirror is adjusted to make it a convex mirror, as Figure 5 shown, the light rays passing through the endoscope optical components are adjusted to parallel light, and then a clear image is obtained on the detector through the imaging mirror; when the distance between the object to be measured and the binocular endoscope detection system is greater than the far - scene depth, the curvature radius of the first deformable mirror is also adjusted to make it a convex mirror, and at the same time the curvature radius of the second deformable mirror is adjusted to make it a concave mirror, as Figure 6 shown, the light rays passing through the endoscope optical components are adjusted to parallel light, and this parallel light passes through the imaging mirror to obtain a clear image on the detector.

[0042] Figure 10 It is a schematic diagram for obtaining two images when the planar mirror is rotated. It can be seen from the figure that since the distance between the object to be measured and the endoscope optical components is the same when the planar mirror is at rotation angle 1 and rotation angle 2, the size of the imaging is the same, but due to the different overall optical path directions, the imaging positions are different.

Claims

1. A binocular endoscopic detection system with variable depth of field, the system comprising an endoscopic optical component, an imaging lens and a detector, characterized in that: It also includes a plane mirror and a deformable mirror group; The light reflected by the object to be measured first turns through the plane mirror, and then is transmitted to the deformable mirror group through the endoscope optical component. After the deformable mirror group collimates the light, it converges to the photosensitive surface of the detector through the imaging lens to obtain a clear image; It also includes a control circuit, and the control circuit is used to control the plane mirror and the deformable mirror group; The control of the plane mirror realizes the translation along the optical axis direction of the endoscope component and the rotation perpendicular to the optical axis direction of the endoscope component; the control of the deformable mirror group realizes the change of the radius of curvature; The deformable mirror group is composed of a first deformable mirror and a second deformable mirror; The radius of curvature of the first deformable mirror and the second deformable mirror is controlled by the control circuit; Translating the plane mirror realizes binocular vision imaging. When the distance between the object to be measured and the binocular endoscope detection system is less than the near-view depth, the control circuit adjusts the radius of curvature of the first deformable mirror to make it a concave mirror, and at the same time adjusts the radius of curvature of the second deformable mirror to make it a convex mirror, and adjusts the light passing through the endoscope optical component into parallel light. The parallel light passes through the imaging lens to obtain a clear image on the detector; When the distance between the object to be measured and the binocular endoscope detection system is greater than the far-view depth, the light passing through the endoscope optical component is converging light. Then the control circuit adjusts the radius of curvature of the first deformable mirror to make it a convex mirror, and at the same time adjusts the radius of curvature of the second deformable mirror to make it a concave mirror, and adjusts the light passing through the endoscope optical component into parallel light. The parallel light passes through the imaging lens to obtain a clear image on the detector.

2. The binocular endoscope detection system with variable depth of field according to claim 1, wherein: Rotating the plane mirror realizes binocular vision imaging. The position of the plane mirror remains unchanged, and the two imaging are both within or outside the depth of field range; When the distance between the object to be measured and the binocular endoscope detection system is less than the near-view depth, the control circuit adjusts the radius of curvature of the first deformable mirror to make it a concave mirror, and adjusts the radius of curvature of the second deformable mirror to make it a convex mirror, and adjusts the light passing through the endoscope optical component into parallel light. The parallel light passes through the imaging lens to obtain a clear image on the detector; When the distance between the object to be measured and the binocular endoscope detection system is greater than the far-view depth, the control circuit adjusts the radius of curvature of the first deformable mirror to make it a convex mirror, and at the same time adjusts the radius of curvature of the second deformable mirror to make it a concave mirror, and adjusts the light passing through the endoscope optical component into parallel light. The parallel light passes through the imaging lens to obtain a clear image on the detector.

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