A device for holding a variable focal length lens assembly

Abstract

The application discloses a kind of vertical zoom lens assembly clamping devices.The application includes lens group, connecting component, support frame, support plate and piezoelectric ceramic linear positioner;Two sides of lens group are installed in corresponding support frame by connecting component, and the support frame of each side of lens group is fixedly installed on corresponding piezoelectric ceramic linear positioner by support plate;The bottom surface of piezoelectric ceramic linear positioner is fixed on base by screw.The approach or distance movement between the piezoelectric ceramic linear positioner of two sides of lens group drives the vertical displacement of lens group on support frame, and the optical axis of lens group is not moved, and the precision vertical zoom of lens group is carried out.The clamping structure of the application ensures that multiple pairs of lenses of vertical zoom lens group have the same vertical displacement amount, and the vertical displacement precision is ensured by piezoelectric ceramic linear positioner, so that the compact installation and zoom function of vertical zoom lens group are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a mirror assembly clamping device, in particular to a vertical-shaft zoom lens assembly clamping device. BACKGROUND

[0002] Optical zoom system has important applications in intelligent security, road monitoring, virtual reality and other fields, and is also the development direction of extraterrestrial detection imaging system. However, due to the conditions such as the total length of optical system and the complexity of zoom motion mechanism, optical zoom is difficult to realize in extraterrestrial detection imaging system.

[0003] The traditional optical zoom technology needs to change the axial position of part of the lenses in the optical system, that is, the distance d between different lenses. The calculation formula of the object side focal length f' of the combined optical system is as follows:

[0004]

[0005] Where f1' and f2' are the focal lengths of the first two lenses.

[0006] In 1967, Luis W Alvarez proposed a lens combination with variable optical power, which includes two free-form lenses. The two lenses have one free-form surface and one plane respectively, and the free-form surfaces have the same shape. In the spatial rectangular coordinate system, let z be the optical axis direction, then the surface height z is a function of x and y, which can be expressed as:

[0007]

[0008] Where A is the surface coefficient. Therefore, the thickness t1 and t2 of the two lenses can be expressed as:

[0009]

[0010]

[0011] Where C1 and C2 are the center thicknesses of the two lenses respectively. Therefore, the superposition thickness T of the two lenses is:

[0012] T(x,y)=t1(x,y)+t2(x,y)

[0013] When the two lenses are vertically displaced by d and -d in the x direction respectively, the superposition thickness T of the two lenses becomes:

[0014] T(x,y)=t1(x-d,y)+t2(x+d,y)

[0015]

[0016] If the lens combination is regarded as a thin lens, the radius of curvature in the paraxial region can be obtained as:

[0017]

[0018] Thus, the focal length f of the varifocal lens group in the paraxial and thin lens case can be obtained as:

[0019]

[0020] where A is the lens surface type coefficient, d is the amount of displacement in the sagittal direction, and n is the refractive index of the lens material. Now, this lens combination using the sagittal movement of the lens for zooming is also called the Alvarez lens. This zooming method can achieve a wider focal length tuning range and shorten the total length of the zoom imaging system.

[0021] In the sagittal zooming method, to achieve the same optical power, if fewer Alvarez lenses are used, the requirement for the refractive index of the lens material is higher, the free-form surface type changes more dramatically, and the displacement in the sagittal direction is larger. The lens group containing multiple pairs of Alvarez lenses can effectively reduce the free-form surface type coefficient, reduce the displacement in the sagittal direction, reduce the pressure on the lens material, and reduce the system aberration.

[0022] However, in related optical designs, the spacing between the Alvarez lenses is often very small, and the lens group composed of multiple pairs of Alvarez lenses needs to ensure the same displacement in the sagittal direction. Therefore, the clamping difficulty and displacement method of the sagittal zoom lens group have become one of the obstacles for the widespread application of the system. SUMMARY

[0023] In order to solve the technical problems existing in the background art, in view of the compactness of the assembly of the Alvarez lens group and the requirement for the same displacement in the sagittal direction of multiple pairs of lenses, the present application provides a sagittal zoom lens group clamping device, which realizes the compact installation of the free-form lens through structural design and cooperation, ensures the high-precision displacement in the sagittal direction of multiple lenses of the lens group through the piezoelectric ceramic linear positioner, and can conveniently install the sagittal zoom lens group in the actual optical system, thereby realizing the sagittal zooming function which is convenient to install and use.

[0024] The technical scheme for achieving the object of the present application is as follows:

[0025] The present application comprises a lens group, a connecting assembly, a support frame, and a piezoelectric ceramic linear positioner. The lens group is installed on the corresponding support frame through the connecting assembly on both sides, and the support frame on each side of the lens group is fixedly installed on the corresponding piezoelectric ceramic linear positioner. The movement of the piezoelectric ceramic linear positioners on both sides of the lens group towards or away from each other drives the lens group on the support frame to produce a displacement in the sagittal direction, thereby realizing the sagittal zooming of the lens group.

[0026] The mirror group comprises a plurality of lenses and a plurality of lens frames, the plurality of lenses are arranged along an optical axis in sequence, each lens is installed in a corresponding lens frame, at least one lens frame of at least one lens in the mirror group is installed in a support frame on one side through a connecting assembly, and the lens frames of the remaining lenses in the mirror group are installed in support frames on the other side through the connecting assembly.

[0027] Among the two adjacent lenses, the coefficients of the zoom term of the surface polynomial of the second light passing surface of the first lens and the coefficients of the zoom term of the surface polynomial of the first light passing surface of the second lens are set to be the same.

[0028] The lenses are at least three.

[0029] The connecting assembly is a limiting ring and a support column, both ends of the support column are installed in the two support frames on each side of the mirror group, the support column is sleeved with the limiting ring, the mirror group is fixedly installed outside the support column, and the limiting ring is used for limiting the mirror group.

[0030] Among the light passing surfaces of the lenses, at least one is a free curved surface conforming to the perpendicular axis zoom method.

[0031] The lens is composed of a light passing part and a pressing ring part, the pressing ring part is arranged at the outer edge of the light passing part, and an axial shoulder is formed between the pressing ring part and the light passing part.

[0032] The light passing part is a waist circle.

[0033] The beneficial effects of the present application are:

[0034] The clamping device of the present application ensures that the multiple pairs of lenses of the perpendicular axis zoom lens group have the same perpendicular axis displacement amount, the perpendicular axis displacement precision is ensured through the piezoelectric ceramic linear positioner, the compact installation and zoom function of the perpendicular axis zoom lens group are realized, the perpendicular axis zoom lens group can be conveniently installed in an actual optical system, and the perpendicular axis zoom function of convenient installation and use is realized. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 It is a schematic diagram of the overall structure of the perpendicular axis zoom lens group clamping device of the present application.

[0036] Figure 2 It is a schematic diagram of the lens.

[0037] Figure 3 It is a schematic diagram of the lens frame.

[0038] Figure 4 It is a schematic diagram of the support frame.

[0039] Figure 5 It is a schematic diagram of the support column.

[0040] Figure 6 It is a schematic diagram of the support plate.

[0041] Figure 7 This is a schematic diagram of the limit ring.

[0042] Figure 8 This is a schematic diagram of a piezoelectric ceramic linear positioner.

[0043] Figure 9 This is a schematic diagram of the mirror assembly when the vertical displacement d = 0 mm.

[0044] Figure 10 This is a schematic diagram of the mirror assembly when the vertical displacement d < 0 mm.

[0045] Figure 11 This is a schematic diagram of the mirror assembly when the vertical displacement d > 0 mm.

[0046] Figure 12 The simulated zoom results for the lens group demonstrate the optical zoom capability of the example lens group.

[0047] In the diagram: lens 1, frame 2, limiting ring 3, support column 4, support frame 5, support plate 6, and piezoelectric ceramic linear positioner 7. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings.

[0049] According to the invention, the complete implementation embodiments and their implementation processes are as follows:

[0050] like Figure 1 As shown, the present invention includes a lens assembly, a connecting component, a support frame 5, a support plate 6, and a piezoelectric ceramic linear positioner 7. The two sides of the lens assembly are mounted in corresponding support frames 5 via the connecting component. Each support frame 5 on each side of the lens assembly is fixedly mounted on a corresponding piezoelectric ceramic linear positioner 7 via the support plate 6. The bottom surface of the piezoelectric ceramic linear positioner is fixed to a base with screws, as shown. Figure 8 As shown, the support frame 5 and the support plate 6, and the support plate 6 and the piezoelectric ceramic linear positioner 7 are fixed together by bolts or screws. The control module controls the movement of the piezoelectric ceramic linear positioners 7 on both sides of the lens assembly, causing the lens assembly on the support frame 5 to produce vertical axis displacement. The optical axis of the lens assembly remains stationary, thus performing precise vertical axis focusing of the lens assembly.

[0051] The lens assembly includes multiple lenses 1 and a frame 2. The multiple lenses 1 are arranged sequentially along the optical axis, and there are at least three lenses 1. Each lens 1 is installed in a corresponding frame 2. The frame 2 containing at least one lens 1 in the lens assembly is installed in a support frame 5 on one side via a connecting assembly, that is, it is finally installed on the first piezoelectric ceramic linear positioner. When the lens assembly has zero displacement, the multiple lenses 1 coincide in the optical axis direction. The frame 2 containing the remaining lenses 1 in the lens assembly is installed in a support frame 5 on the other side via a connecting assembly, that is, it is finally installed on the second piezoelectric ceramic linear positioner.

[0052] Along the optical axis of the lens group, the two light-transmitting surfaces of lens 1 are respectively designated as the first light-transmitting surface and the second light-transmitting surface. In two adjacent lenses 1, the zoom term coefficient of the surface polynomial of the second light-transmitting surface of the first lens is set to be the same as the zoom term coefficient of the surface polynomial of the first light-transmitting surface of the second lens. Among the light-transmitting surfaces of lens 1, at least one surface is a freeform surface that conforms to the transverse zoom method.

[0053] Lens 1 consists of a light-transmitting part and a retaining ring part. The retaining ring part is located on the outer edge of the light-transmitting part, and a shoulder is formed between the retaining ring part and the light-transmitting part. The retaining ring part has the same width and thickness, and the center of the light-transmitting part is thicker than the retaining ring part. The retaining ring part is glued to the frame, so that the light-transmitting part is fitted into the frame. The light-transmitting part is oval, that is, the shape formed by two semicircles spliced ​​on both sides of a rectangle.

[0054] The connecting components are a limiting ring 3 and a support column 4. The two ends of the support column 4 are respectively installed in two support frames 5 on each side of the lens assembly. The limiting ring 3 is fitted over the support column 4. The lens frame 2 of the lens assembly is fixedly installed outside the support column 4 by set screws. The lens assembly is in contact with the limiting ring 3, which is used to limit the movement of the lens assembly. Figure 1 and Figure 3 As shown, the two left frames 2 are limited by two limiting rings on both sides, and the two right frames 2 are limited by one limiting ring between them.

[0055] Figure 2 The image shows the shape of the lens, and... Figure 3 The openings in the frame match, allowing for bonding between the countersunk holes in the frame and the lens retaining ring, thus securing the lens to the frame.

[0056] Figure 3 The middle frame has two support through holes, which allow the lens and frame to be fixed in a plane perpendicular to the optical axis using two support posts. The side of the frame has two screw holes, located at the center height of the support through holes, for installing set screws to secure the frame and lens to the support posts.

[0057] Figure 4 and Figure 5The support frame and the support column are respectively shown, the through hole shape of the support frame is matched with the two ends of the support column, and the support frame plays a fixing role on the support column to prevent the support column from sliding in the axial direction or rotating around the shaft.

[0058] Figure 6 The support plate is shown, which plays a role in connecting the upper support frame and the lower piezoelectric ceramic linear positioner. In the example support plate, the four round holes in the middle area correspond to the screw holes on the top surface of the piezoelectric ceramic linear positioner, and the remaining four round holes are in pairs corresponding to the screw holes on the bottom surface of the two support frames.

[0059] Figure 7 The limiting ring is shown in the middle, which is used to be installed on the support column and plays a limiting role on the frame in the axial direction, fixing the frame and the lens in the appropriate axial position.

[0060] By fixing the support frame on the support plate, the relative positions of the support column, the frame, the lens, and the support plate can be ensured, and the clamping structure of the lens group is formed.

[0061] When using the lens group in the application, the support plate and the piezoelectric ceramic linear positioner need to be fixed, and then the piezoelectric ceramic linear positioner is fixed on the optical platform. As long as the piezoelectric ceramic linear positioner is installed in the correct position, the lens in the lens group can be ensured to be in the correct position in the optical path.

[0062] When zooming, the entire lens group is moved by the closed-loop positioning and displacement function of the piezoelectric ceramic linear positioner, and the lens group is controlled to achieve precise displacement in the vertical axis direction. The displacement generated by the movement of the piezoelectric ceramic linear positioner is positive, and vice versa, as shown in Figures 9-11 .

[0063] Figure 12 The example lens group is shown in the middle, and the zooming ability of the lens group in five vertical displacement conditions is shown. To show the zooming ability, an ideal lens with a focal length of 25 mm is added behind the vertical zooming lens group in the simulation software.

[0064] The relationship between the distance L from the ideal lens to the image plane and the vertical displacement d of the lens group in the five cases is listed in Table 1. Figure 12

[0065] Table 1: Relationship between distance L from ideal lens to image plane and vertical displacement d of lens group in five cases

[0066] ​

Claims

1. A vertical axis zoom lens assembly clamping device, characterized in that, The mirror group, the connecting assembly, the support frame (5) and the piezoelectric ceramic linear positioner (7); the mirror group is installed in the corresponding support frame (5) through the connecting assembly on both sides, and the support frame (5) on each side of the mirror group is fixedly installed on the corresponding piezoelectric ceramic linear positioner (7); the piezoelectric ceramic linear positioner (7) on both sides of the mirror group is close or far from each other, which drives the mirror group on the support frame (5) to produce a vertical axis displacement, and the vertical axis zoom of the mirror group is performed. The mirror group includes a plurality of lenses (1) and a mirror frame (2), the lenses (1) are arranged along the optical axis in sequence, each lens (1) is installed in the corresponding mirror frame (2), and at least one lens (1) in the mirror group is installed in the support frame (5) on one side through the connecting assembly, and the remaining lenses (1) in the mirror group are installed in the support frame (5) on the other side through the connecting assembly.

2. A device for holding a lens assembly according to claim 1, wherein In the two adjacent lenses (1), the coefficients of the zoom terms of the face type polynomials of the second light passing surface of the first lens and the first light passing surface of the second lens are set to be the same.

3. A device for holding a lens barrel assembly according to claim 1, wherein The lenses (1) are at least 3.

4. A device for holding a lens barrel assembly according to claim 1, wherein The connecting assembly is a limiting ring (3) and a support column (4), both ends of the support column (4) are installed in the two support frames (5) on each side of the mirror group, the support column (4) is sleeved with the limiting ring (3), the mirror group is fixedly installed outside the support column (4), and the limiting ring (3) is used for limiting the mirror group.

5. A device for holding a lens barrel assembly according to claim 1, wherein At least one of the light passing surfaces of the lens (1) is a free curved surface conforming to the vertical axis zoom method.

6. A device for holding a lens barrel assembly according to claim 1, wherein The lens (1) is composed of a light passing part and a pressing ring part, the pressing ring part is arranged at the outer edge of the light passing part, and an axial shoulder is formed between the pressing ring part and the light passing part.

7. A device for holding a lens barrel assembly according to claim 6, wherein The light passing part is a waist circle.

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