A continuous zoom lens

Abstract

The present application relates to a kind of continuous zoom lens, belong to the field of optoelectronic technology, solve the problem of not enough smooth, stable in continuous zooming process in prior art.A kind of continuous zoom lens includes lens, lens barrel, cam, zoom motor and gear;Cam includes inner and outer cams, outer cam is rotatably sleeved on inner cam, inner cam is sleeved on zooming, compensation group lens barrel, zooming group, compensation group lens barrel is respectively fixed with zooming, compensation group pin;Outer cam side wall has the zooming guide slot according to zooming group outer cam curve processing, the compensation guide slot according to compensation group outer cam curve processing, zooming group outer cam curve and compensation group outer cam curve are the curve obtained by optimization algorithm of particle swarm optimization.8 times continuous zooming is realized, optical system structure is compact, volume weight is smaller, and zooming group and compensation group are moved according to optimal curve mode, the suppression of the maximum pressure angle of cam curve is realized, and the zooming process is smooth, stable, and the imaging quality is good.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, and more particularly to a continuous zoom lens. Background Technology

[0002] As modern warfare evolves towards lighter and unmanned operations, optical systems must achieve both wide-field observation and search capabilities as well as narrow-field tracking and aiming. Therefore, resolving the conflict between field of view and viewing distance has become a key focus in the design of optoelectronic reconnaissance systems. Continuous zoom systems change the focal length of the lens by altering the spacing between lenses, thereby obtaining different field of view angles and scene ranges. They maintain image continuity and image quality stability throughout the field of view switching process, making them highly suitable for searching and tracking high-speed targets. In recent years, continuous zoom systems have become a trend, necessitating the design of a zoom lens with high imaging quality, high zoom ratio, compact structure, and smooth and stable zooming process.

[0003] Designing high-quality continuous zoom lenses in the current technology is quite difficult, often resulting in problems such as jamming during zooming or inability to guarantee image clarity throughout the zooming process. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a continuous zoom lens to solve the problems that existing continuous zoom lenses often have, such as easy jamming during zooming or inability to guarantee image quality throughout the zooming process.

[0005] This invention provides a continuous zoom lens, which includes a zoom lens group, a compensation lens group, a zoom lens group barrel, a compensation lens group barrel, a cam, a zoom motor, and gears.

[0006] The zoom lens and the compensation lens are respectively installed in the zoom lens barrel and the compensation lens barrel;

[0007] The cam includes an outer cam and an inner cam. The outer cam is rotatably mounted on the inner cam, and the inner cam is mounted on the zoom group lens barrel and the compensation group lens barrel. The zoom group lens barrel and the compensation group lens barrel are respectively fixed with zoom group pins and compensation group pins. The sidewall of the outer cam has a zoom guide groove machined according to the curve of the zoom group outer cam and a compensation guide groove machined according to the curve of the compensation group outer cam. The curves of the zoom group outer cam and the compensation group outer cam are curves obtained by particle swarm optimization algorithm.

[0008] The variable magnification pin passes through the linear guide groove of the inner cam and the variable magnification guide groove of the outer cam, and the compensation pin passes through the linear guide groove of the inner cam and the compensation guide groove of the outer cam.

[0009] The zoom motor drives the outer cam to rotate via gears. The outer cam drives the zoom group pin and the compensation group pin to move in the guide grooves in the outer cam and the inner cam, thereby driving the zoom group lens and the compensation group lens to move accordingly along the optical axis, completing the continuous zoom of the optical system.

[0010] Furthermore, the external cam curves of the zoom group and the compensation group are obtained as follows:

[0011] Construct an initial logarithmic function y = log[a, b] on the interval [a, b]. c x;

[0012] The initial logarithmic function is uniformly sampled to obtain N sampling points;

[0013] Based on the coordinates of the sampling points and the range of sampling points of the zoom group and compensation group along the vertical optical axis, the sampling points x1 of the zoom group and compensation group along the vertical optical axis are obtained. i x2 i ;

[0014] Wherein the sampling point x1 i x2 i And the interval [a, b] satisfies the preset optimization constraints;

[0015] Based on the sampling point z1 along the optical axis of the zoom group i Sampling point x1 along the direction perpendicular to the optical axis i Polynomial fitting is performed to obtain the external cam curve of the zoom group; based on the sampling point z2 along the optical axis of the compensation group. i Sampling point x2 along the direction perpendicular to the optical axis i Polynomial fitting is performed to obtain the external cam curve of the compensation group;

[0016] The pressure angle and the mean pressure angle of each sampling point are obtained based on the external cam curve of the variable magnification group and the external cam curve of the compensation group.

[0017] A fitness function is constructed based on the pressure angle and the mean pressure angle of the variable-amplitude group and the compensation group.

[0018] The particle swarm optimization algorithm is used to optimize parameters a, b, and c to find the optimal parameters when the fitness function is optimal. The external cam curves of the zoom group and the compensation group obtained based on the optimal parameters are the final optimized external cam curves of the zoom group and the compensation group.

[0019] Furthermore, the sampling point x1 i x2 i And the interval [a, b] satisfies the preset optimization constraints, including: (1)

[0021] min(x1 i+1-x1 i )≥δ ma ,

[0022] min(x2 i+1 -x2 i )≥δ ma ,

[0023] Where, δ ma Indicates machining precision;

[0024] (2) The range Δ along the vertical optical axis remains unchanged after the external cam curves of the variable magnification group and the external cam curves of the compensation group are developed into planar curves before and after optimization.

[0025] (3) The distance between adjacent sampling points of the planar curve formed by each outer cam curve in the direction perpendicular to the optical axis is greater than the accuracy of the zoom motor:

[0026] min(x1 i+1 -x1 i )≥δ mo ,

[0027] min(x2 i+1 -x2 i )≥δ mo

[0028] Where, δ mo Indicates the precision of the zoom motor;

[0029] (4) The spacing between adjacent sampling points of the planar curve formed by each outer cam curve in the direction perpendicular to the optical axis satisfies:

[0030] max(x1 i+1 -x1 i )≤min(m1δ ma ,m1δ mo ),

[0031] max(x2 i+1 -x2 i )≤min(m1δ ma ,m1δ mo )

[0032] Where m1 represents the weighting coefficient, and the range of m1 is [1, 3];

[0033] (5)

[0034]

[0035] Where D is the diameter of the pin, m2 represents the weighting coefficient, m2 ranges from [1, 3], f1 represents the function of x1 on the plane curve developed by the external cam curve of the variable magnification group, and f2 represents the function of x2 on the plane curve developed by the external cam curve of the compensation group.

[0036] (6) Construct an initial logarithmic function y = log [a, b] on the interval [a, b]. c The selection of x, a, b, and c should make y greater than 0, where a, b, and c are optimization parameters.

[0037] Furthermore, the initial logarithmic function is uniformly sampled to obtain N sampling points; based on the coordinates of the sampling points and the interval range of the sampling points of the zoom group and compensation group along the vertical optical axis, the sampling points x1 of the zoom group and compensation group along the vertical optical axis are obtained. i x2 i ,include:

[0038] For the constructed interval logarithmic function, N points are uniformly sampled within the interval [a, b] to obtain the coordinates of the sampling points (x, y) of the independent variable x and the dependent variable y based on the logarithmic function. i ,y i ), where N equals the sampling point z1 of each outer cam curve along the optical axis. i or z2 i The number of sampling points of the logarithmic function; the y-coordinate of the sampling points. i After normalization and mapping to the interval Δ, we get:

[0039]

[0040]

[0041] Where y min =log c a,y max =log c b.

[0042] Furthermore, the continuous zoom lens also includes a front fixed lens group and a rear fixed lens group;

[0043] The lenses, from object to image, are as follows: front fixed lens group, zoom lens group, compensation lens group, and rear fixed lens group.

[0044] Furthermore, the sampling point z1 of the zoom group along the optical axis direction i Sampling point z2 of the compensation group along the optical axis i for:

[0045] During the process of the lens changing from a short focal length to a long focal length, N sampling points z1 are uniformly sampled. i and z2 iThe z1 i z2 is the distance along the optical axis between the most convex point of the zoom lens closest to the object and the lens closest to the image of the front fixed lens at different focal lengths; i This is the distance along the optical axis between the most convex point of the compensation lens closest to the object and the lens closest to the image of the front fixed lens at different focal lengths.

[0046] Furthermore, the fitness function is:

[0047]

[0048] Among them, f zi f represents the pressure angle at the sampling point of the zoom group; ci Indicates the pressure angle at the sampling point of the compensation group; f zmean f represents the average pressure angle of the sampling points in the zoom group; cmean λ1 represents the average pressure angle of the sampling points in the compensation group; λ2 represents the weighting coefficients of the zoom lens group and the compensation lens group, respectively.

[0049] Furthermore, the front fixed lens group includes a positive power cemented lens formed by cementing a first lens and a second lens together, and a positive power third lens.

[0050] The zoom lens group includes a fourth lens with negative optical power and a cemented lens with negative optical power formed by cementing a fifth lens and a sixth lens together.

[0051] The compensation lens group includes a positive optical power cemented lens formed by cementing the seventh and eighth lenses together, and a positive optical power ninth lens.

[0052] The rear fixed lens group includes a tenth lens with negative optical power, an eleventh lens with positive optical power, a negative optical power cemented lens formed by cementing the twelfth and thirteenth lenses together, and a fourteenth lens with positive optical power.

[0053] The distances between the front fixed group lens and the rear fixed group lens and the image plane are fixed, while the distances between the zoom group lens and the compensation group lens and the image plane in the optical axis direction are adjustable.

[0054] Furthermore, the focal length of the lens ranges from 20.00mm to 159.95mm, and the f-number is from 3.89 to 5.80.

[0055] Furthermore, the first to the fourteenth lenses are all spherical glass lenses.

[0056] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0057] 1. The continuous zoom lens external cam curve optimization method of the present invention utilizes the particle swarm optimization algorithm. It reduces the pressure angle by optimizing the fitness function and directly optimizes the cam curve by fitting the sampling points in the x-direction of the cam using a log function, thereby suppressing the maximum pressure angle of the two cam curves. This makes the automatic continuous zoom process smoother and less prone to jamming.

[0058] 2. The fitness function of this invention considers the pressure angles of the two external cam curves simultaneously. Therefore, the optimized two external cam curves, under the constraints of imaging tolerance and the tolerances of zoom motor and machining accuracy, appropriately widen the local area with a large pressure angle along the x-direction and appropriately shrink the local area with a small pressure angle along the x-direction to reduce the peak value of the pressure angle α in the external cam curve and avoid the problem of motor stalling during operation.

[0059] 3. The zoom group and compensation group of the present invention move along the zoom curve under the drive of the motor, ensuring that the zoom group and compensation group lenses pass through the preset sampling points, so that the image is clear and stable throughout the zoom process.

[0060] 4. The continuous zoom lens of this invention patent can achieve a large zoom ratio, while the system structure is compact and the size is small.

[0061] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0062] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0063] Figure 1 This is a schematic diagram of a continuous zoom lens structure according to the present invention;

[0064] Figure 2 This is a schematic diagram of the optical lens structure of a continuous zoom lens according to the present invention;

[0065] Figure 3 This is a diagram showing the relationship between the component spacing and the system focal length of a continuous zoom lens according to the present invention.

[0066] Figure 4 This invention relates to a short focal length field curvature-distortion curve for a continuous zoom lens;

[0067] Figure 5This invention provides a short-focus MTF curve for a continuous zoom lens.

[0068] Figure 6 This invention relates to a telephoto field curvature-distortion curve for a continuous zoom lens;

[0069] Figure 7 This invention provides a telephoto MTF curve for a continuous zoom lens.

[0070] Figure 8 This invention relates to an unoptimized zoom curve and pressure angle curve for a continuous zoom lens.

[0071] Figure 9 This invention provides an optimized zoom curve and pressure angle curve for a continuous zoom lens.

[0072] Figure label:

[0073] 1-Distance between the rear fixation group and the front fixation group;

[0074] 2- Distance between the compensation group and the previous fixed group;

[0075] 3-Distance between the variable magnification group and the previous fixed magnification group. Detailed Implementation

[0076] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0077] A specific embodiment of the present invention discloses a continuous zoom lens, which includes a zoom lens group, a compensation lens group, a zoom lens group barrel, a compensation lens group barrel, a cam, a zoom motor, and gears;

[0078] The zoom lens and the compensation lens are respectively installed in the zoom lens barrel and the compensation lens barrel;

[0079] The cam includes an outer cam and an inner cam. The outer cam is rotatably mounted on the inner cam, and the inner cam is mounted on the zoom group lens barrel and the compensation group lens barrel. The zoom group lens barrel and the compensation group lens barrel are respectively fixed with zoom group pins and compensation group pins. The sidewall of the outer cam has a zoom guide groove machined according to the curve of the zoom group outer cam and a compensation guide groove machined according to the curve of the compensation group outer cam. The curves of the zoom group outer cam and the compensation group outer cam are curves obtained by particle swarm optimization algorithm.

[0080] The variable magnification pin passes through the linear guide groove of the inner cam and the variable magnification guide groove of the outer cam, and the compensation pin passes through the linear guide groove of the inner cam and the compensation guide groove of the outer cam.

[0081] The zoom motor drives the outer cam to rotate via gears. The outer cam drives the zoom group pin and the compensation group pin to move in the guide grooves in the outer cam and the inner cam, thereby driving the zoom group lens and the compensation group lens to move accordingly along the optical axis, completing the continuous zoom of the optical system.

[0082] Specifically, such as Figure 2 As shown, the continuous zoom lens also includes a front fixed lens group and a rear fixed lens group;

[0083] The lenses, from object to image, are as follows: front fixed lens group, zoom lens group, compensation lens group, and rear fixed lens group.

[0084] The front fixed lens group includes a positive power cemented lens formed by cementing a first lens and a second lens together, and a positive power third lens.

[0085] The zoom lens group includes a fourth lens with negative optical power and a cemented lens with negative optical power formed by cementing a fifth lens and a sixth lens together.

[0086] The compensation lens group includes a positive optical power cemented lens formed by cementing the seventh and eighth lenses together, and a positive optical power ninth lens.

[0087] The rear fixed lens group includes a tenth lens with negative optical power, an eleventh lens with positive optical power, a negative optical power cemented lens formed by cementing the twelfth and thirteenth lenses together, and a fourteenth lens with positive optical power.

[0088] The distances between the front fixed group lens and the rear fixed group lens and the image plane are fixed, while the distances between the zoom group lens and the compensation group lens and the image plane in the optical axis direction are adjustable.

[0089] The focal length of the lens ranges from 20.00mm to 159.95mm, and the f-number is from 3.89 to 5.80.

[0090] The first to the fourteenth lenses are all spherical glass lenses.

[0091] A specific embodiment of the continuous zoom lens of the present invention, such as... Figure 1 As shown, the continuous zoom lens consists of a lens barrel, a cam, a lens, a pressure ring, a spacer, a zoom motor, and gears.

[0092] The lens barrel includes a zoom lens barrel, a compensation lens barrel, a front fixed lens barrel, and a rear fixed lens barrel. The lens barrel, pressure ring, and spacer are used to mount the corresponding optical lenses. The inner cam has two straight guide grooves, and the outer cam has two curved guide grooves. A zoom group pin and a compensation group pin are fixed to the zoom barrel and compensation group barrel, respectively. The zoom group pin passes through the straight guide groove of the inner cam and the zoom guide groove of the outer cam, and the compensation group pin passes through the straight guide groove of the inner cam and the compensation guide groove of the outer cam. When the zoom motor drives the outer cam to rotate via gears, the inner cam remains stationary. The rotation of the outer cam causes the zoom group pin and the compensation group pin to move within the guide grooves of the outer and inner cams, thereby causing the zoom group barrel and zoom group lens, and the compensation group barrel and compensation group lens to move accordingly along the optical axis. This allows the zoom group lens and the compensation group lens to move between short focal length and long focal length. The front fixed group provides a fixed image for the system, and the zoom group plays a zooming role during zooming, with a total stroke of 29.24 mm. As the zoom group moves, the compensation group moves accordingly. During zooming, the compensation group compensates for image plane aberrations, enabling large zoom ratios and ensuring a clear and stable image plane throughout the zoom range. The total travel is 28.0 mm. The rear fixed group is used to complete the final imaging and compensate for system aberrations.

[0093] Lens parameters are shown in Table 1.

[0094] Table 1

[0095]

[0096]

[0097] Specifically, the field of view 2ω of the zoom lens is 2.72°-21.5°.

[0098] The resulting lens has a maximum aperture of Ф33.59mm and a total length of 140.02mm, achieving a miniaturized and lightweight design.

[0099] The focal length range and F-number of the lens of this invention achieve a large zoom range.

[0100] The present invention obtains the external cam curve of the variable magnification group and the external cam curve of the compensation group, specifically including steps S1-S5.

[0101] Step S1: Construct an initial logarithmic function y = log [a, b] over the interval [a, b]. c x; uniformly sample the initial logarithmic function to obtain N sampling points.

[0102] The initial logarithmic function y = log [a, b] is constructed on the interval [a, b]. c The selection of x, a, b, and c should make y greater than 0, where a, b, and c are optimization parameters.

[0103] For the constructed interval logarithmic function, N points are uniformly sampled within the interval [a, b] to obtain the coordinates of the sampling points (x, y) of the independent variable x and the dependent variable y based on the logarithmic function. i ,y i ), where N equals the sampling point z1 of each outer cam curve along the optical axis. i or z2 i The number of elements. In one specific embodiment of the present invention, N = 200.

[0104] The external cam curve optimization method is based on the results of optical design, starting from the basic formula of the pressure angle:

[0105]

[0106]

[0107] Among them, z1 i z2 i To ensure uniform sampling points along the optical axis, the sampling points must be determined before designing the outer cam curves of the zoom group and compensation group to guarantee clear sampling throughout the imaging process. As shown by the pressure angle formula, the optimized design of the pressure angle of the outer cam curve can be obtained by adjusting the position in the z-direction (along the optical axis) or by adjusting the spacing perpendicular to the optical axis after the outer cam curve is unfolded into a plane. However, for a given optical design, to ensure image clarity and optical axis stability, this embodiment of the invention employs a method of widening the curve in the x-direction to reduce the maximum pressure angle of the cam curve.

[0108] Specifically, when the outer cam curve undergoes nonlinear broadening in the direction perpendicular to the optical axis, it should satisfy the condition that the sampling points in the direction perpendicular to the optical axis change significantly at the short focal length position and decrease significantly at the long focal length position. This characteristic matches the trend of the logarithmic function. Therefore, this invention uses a logarithmic function to nonlinearly broaden the outer cam curve along the direction perpendicular to the optical axis. Because the mapped logarithmic function values ​​must correspond one-to-one with the sampling points of the outer cam curve in the direction perpendicular to the optical axis, the selected logarithmic function interval [a, b] is constrained to ensure that the function value is greater than 0.

[0109] Step S2: Based on the coordinates of the sampling points and the range of sampling points of the zoom group and compensation group along the vertical optical axis, obtain the sampling points x1 of the zoom group and compensation group along the vertical optical axis. i x2 i .

[0110] The ordinate of the logarithmic function sampling point y i After normalization and mapping to the interval Δ, we get:

[0111]

[0112]

[0113] Where y min =log c a,y max =log c b, Δ is the range along the vertical optical axis after the outer cam curves of the variable magnification group and the compensation group are developed into planar curves before and after optimization. The two outer cam curves have the same Δ.

[0114] Wherein, the sampling point x1 i x2 i The preset optimization constraints must be met, specifically including (1)-(5).

[0115] (1) min(x1 i+1 -x1 i )≥δ ma ,

[0116] min(x2 i+1 -x2 i )≥δ ma ,

[0117] Where, δ ma Indicates machining precision;

[0118] Specifically, while ensuring image quality, the amount of movement in the direction perpendicular to the optical axis is controlled within the range of machining accuracy.

[0119] (2) The range Δ along the vertical optical axis remains unchanged after the external cam curves of the variable magnification group and the external cam curves of the compensation group are developed into planar curves before and after optimization.

[0120] (3) The distance between adjacent sampling points of the planar curve formed by each outer cam curve in the direction perpendicular to the optical axis is greater than the accuracy of the zoom motor:

[0121] min(x1 i+1 -x1 i )≥δ mo ,

[0122] min(x2 i+1 -x2 i )≥δ mo

[0123] Where, δ mo Indicates the precision of the zoom motor;

[0124] Specifically, the vertical optical axis movement of each discrete sampling point of the outer cam curve is greater than the accuracy of the zoom motor's rotation drive, ensuring that the system's focal length change has a certain degree of uniformity.

[0125] (4) The spacing between adjacent sampling points of the planar curve formed by each outer cam curve in the direction perpendicular to the optical axis satisfies:

[0126] max(x1 i+1 -x1 i )≤min(m1δ ma ,m1δ mo ),

[0127] max(x2 i+1 -x2 i )≤min(m1δ ma ,m1δ mo )

[0128] Where m1 represents the weighting coefficient, and the range of m1 is [1, 3];

[0129] Specifically, the spacing between adjacent sampling points is constrained to ensure minimal image plane drift during the movement of adjacent sampling points;

[0130] (5)

[0131]

[0132] Where D is the diameter of the pin, m2 represents the weighting coefficient, m2 ranges from [1, 3], f1 represents the function of x1 on the plane curve developed by the external cam curve of the variable magnification group, and f2 represents the function of x2 on the plane curve developed by the external cam curve of the compensation group.

[0133] Specifically, constraint (5) makes the two outer cam curves smooth and controls the occurrence of inflection points in a local small area of ​​the outer cam curves.

[0134] Under the constraints of imaging tolerance and the tolerance of zoom motor and machining accuracy, the local area with a large pressure angle of the curve is appropriately widened along the x-direction, and the local area with a small pressure angle of the curve is appropriately reduced along the x-direction, so as to reduce the peak value of pressure angle α in the outer cam curve and avoid the problem of motor stalling during operation.

[0135] Step S3: Based on the sampling point z1 along the optical axis of the zoom group i Sampling point x1 along the direction perpendicular to the optical axis i Polynomial fitting is performed to obtain the external cam curve of the zoom group; based on the sampling point z2 along the optical axis of the compensation group. i Sampling point x2 along the direction perpendicular to the optical axis i Polynomial fitting is performed to obtain the external cam curve of the compensation group.

[0136] Specifically, the sampling point z1 of the zoom group along the optical axis direction iSampling point z2 of the compensation group along the optical axis i for:

[0137] During the process of the lens changing from a short focal length to a long focal length, N sampling points z1 are uniformly sampled. i and z2 i The z1 i z2 is the distance along the optical axis between the most convex point of the zoom lens closest to the object and the lens closest to the image of the front fixed lens at different focal lengths; i This represents the distance along the optical axis between the most convex point of the compensation group lens (closest to the object) and the lens of the front fixed group lens (closest to the image). Understandably, during zooming, the zoom group and the compensation group move simultaneously, acquiring the corresponding sampling point z1 at each focal length position. i and z2 i .

[0138] In one specific embodiment of the present invention, a 6th-order polynomial is used to fit the equation:

[0139] f(x) = p1x 6 +p2x 5 +p3x 4 +p4x 3 +p5x 2 +p6x+p7,

[0140] z1 i and z2 i As the function value f(x) of the fitted equation, x1 i x2 i As the x value in the fitted equation, x1 i z1 i Fit the external cam curve of the zoom group, from x2 i z2 i Fit the external cam curve of the compensation group.

[0141] Step S4: Obtain the pressure angle and the mean pressure angle of each sampling point based on the external cam curve of the variable magnification group and the external cam curve of the compensation group; construct a fitness function based on the pressure angle and the mean pressure angle of the variable magnification group and the compensation group.

[0142] Specifically, after obtaining the external cam curves of the variable magnification group and the external cam curves of the compensation group, the pressure angle of each point and the mean of the pressure angle of each point are calculated based on the sampling points in the curves; a fitness function is constructed based on the pressure angles and the mean of the pressure angles of the two curves.

[0143] Specifically, the fitness function is:

[0144]

[0145] Among them, f zi f represents the pressure angle at the sampling point of the zoom group; ci Indicates the pressure angle at the sampling point of the compensation group; f zmean f represents the average pressure angle of the sampling points in the zoom group; cmean λ1 represents the average pressure angle of the sampling points in the compensation group; λ2 represents the weighting coefficients of the zoom lens group and the compensation lens group, respectively.

[0146] Step S5: Optimize parameters a, b, and c using the particle swarm optimization algorithm to find the optimal parameters when the fitness function is optimal. The external cam curves of the zoom group and compensation group obtained based on the optimal parameters are the final optimized external cam curves of the zoom group and compensation group.

[0147] The particle swarm optimization algorithm is used to find the optimal variable parameters of the logarithmic function, thereby obtaining the optimal external cam curve. Specifically, for randomly selected optimization parameters a, b, and c, 1000 or more sets can be selected. MATLAB software is used for simulation to test whether the constraints are met. If not, the corresponding optimization parameters are discarded; if they are met, the fitness function is calculated. Through 1000-10000 iterations of parameter optimization, the two external cam curves corresponding to the minimum fitness function value are found.

[0148] Figure 4 , Figure 5 This is an aberration analysis diagram of a specific embodiment of the continuous zoom lens of the present invention in a short focal length state, i.e., a focal length of 20.00mm.

[0149] Figure 6 , Figure 7 This is an aberration analysis diagram of a specific embodiment of the continuous zoom lens of the present invention in the telephoto state, i.e., at a focal length of 159.98mm.

[0150] Figure 8 These are unoptimized zoom and pressure angle curves. For ease of demonstration, the absolute values ​​of the pressure angle curves of the compensation group are taken. As shown in the figure, the maximum pressure angle of the zoom group is 72.3°, and the maximum pressure angle of the compensation group is 52.6°, which cannot meet the design requirements of the cam curve pressure angle.

[0151] Figure 9 The zoom curve and pressure angle curve are optimized by the particle swarm optimization algorithm. As shown in the figure, the maximum pressure angle of the zoom group is 44.8° and the maximum pressure angle of the compensation group is 44.1°, both of which are less than 45°, which can meet the design requirements of the pressure angle of the external cam curve.

[0152] Taking the 8x zoom lens design provided by this invention as an example, the zoom cam diameter R = 25mm, and the range Δ in the direction perpendicular to the optical axis is 45mm. Figure 3The zoom curve shown uses 200 points each for the zoom group and compensation group on the vertical axis as the lens sampling points z1 along the optical axis. i z2 i Based on the above sampling points, the following design was implemented: Figure 9 The external cam curve shown in figure a.

[0153] Compared with existing technologies, the continuous zoom lens provided in this embodiment has the following advantages over other lenses: The continuous zoom lens external cam curve optimization method of this invention utilizes the particle swarm optimization algorithm to reduce the pressure angle by optimizing the fitness function, and directly optimizes the cam curve by fitting the sampling points of the cam x-direction with a log function, thereby suppressing the maximum pressure angle of the two cam curves. This makes the automatic continuous zoom process smoother and less prone to jamming. The fitness function of this invention considers the pressure angles of both outer cam curves simultaneously. Therefore, the optimized two outer cam curves, under the constraints of imaging tolerances and the tolerances of the zoom motor and machining accuracy, appropriately widen the local areas with large pressure angles along the x-direction and appropriately shrink the local areas with small pressure angles along the x-direction to reduce the peak value of the pressure angle α in the outer cam curves and avoid the problem of motor stalling during operation. The zoom group and compensation group of this invention move along the zoom curve under the drive of the motor, ensuring that the zoom group and compensation group lenses pass through the preset sampling points, making the image clear and stable throughout the zoom process. The continuous zoom lens of this invention can achieve a large zoom ratio, while the system structure is compact and the size is small.

[0154] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0155] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A continuous zoom lens, characterized in that, A continuous zoom lens consists of the following components from the object side to the image side: front fixed lens group, zoom lens group, compensation lens group, and rear fixed lens group. Continuous zoom lenses also include: zoom lens barrel, compensation lens barrel, cam, zoom motor and gears; The zoom lens and the compensation lens are respectively installed in the zoom lens barrel and the compensation lens barrel; The cam includes an outer cam and an inner cam. The outer cam is rotatably mounted on the inner cam, and the inner cam is mounted on the zoom group lens barrel and the compensation group lens barrel. A zoom group pin and a compensation group pin are respectively fixed on the zoom group lens barrel and the compensation group lens barrel. The sidewall of the outer cam has a zoom guide groove machined according to the curve of the zoom group outer cam and a compensation guide groove machined according to the curve of the compensation group outer cam. The curves of the zoom group outer cam and the compensation group outer cam are curves optimized by a particle swarm optimization algorithm. The curves of the zoom group outer cam and the compensation group outer cam are obtained in the following way: Construct an initial logarithmic function for the interval [a, b]. ; The initial logarithmic function is uniformly sampled to obtain N sampling points; Based on the coordinates of the sampling points and the range of sampling points of the zoom group and compensation group along the vertical optical axis, the sampling points of the zoom group and compensation group along the vertical optical axis are obtained. , ,include: The independent variable of the constructed interval logarithmic function By uniformly sampling N points within the range [a, b], we obtain the independent variable based on the logarithmic function. and dependent variable Sampling point coordinates Where N equals the number of sampling points along the optical axis for each outer cam curve. or The number of sampling points of the logarithmic function; the ordinate of the sampling points. After normalization and mapping to the interval Δ, we get: ， ， in , Δ represents the external cam curve of the variable magnification group and the external cam of the compensation group. The range of the curve along the vertical optical axis after it has been flattened into a planar curve before and after optimization; The sampling points , The interval [a, b] satisfies preset optimization constraints, including: the initial logarithmic function for the constructed interval [a, b]. , The choice should make Greater than 0, where, To optimize parameters; The sampling points of the zoom group along the optical axis Sampling points of the compensation group along the optical axis for: A continuous zoom lens uniformly samples N sampling points during the process of changing from a short focal length to a long focal length. and The The distance along the optical axis between the most convex point of the zoom lens closest to the object and the lens closest to the image of the front fixed lens at different focal lengths; The distance along the optical axis is the distance between the most convex point of the compensation group lens closest to the object and the lens closest to the image of the front fixed group lens at different focal lengths. Based on the sampling points along the optical axis of the zoom group Sampling points along the vertical optical axis Polynomial fitting is performed to obtain the external cam curve of the zoom group; sampling points along the optical axis are based on the compensation group. Sampling points along the vertical optical axis Perform polynomial fitting to obtain the external cam curve of the compensation group; The pressure angle and the mean pressure angle of each sampling point are obtained based on the external cam curve of the variable magnification group and the external cam curve of the compensation group. A fitness function is constructed based on the pressure angle and the mean pressure angle of the variable-amplitude group and the compensation group. The particle swarm optimization algorithm is used to optimize parameters a, b, and c to find the optimal parameters when the fitness function is optimal. The external cam curves of the zoom group and the compensation group obtained based on the optimal parameters are the final optimized external cam curves of the zoom group and the compensation group. The variable magnification pin passes through the linear guide groove of the inner cam and the variable magnification guide groove of the outer cam, and the compensation pin passes through the linear guide groove of the inner cam and the compensation guide groove of the outer cam. The zoom motor drives the outer cam to rotate via gears. The outer cam drives the zoom group pin and the compensation group pin to move in the guide grooves in the outer cam and the inner cam, thereby driving the zoom group lens and the compensation group lens to move accordingly along the optical axis, completing the continuous zoom of the optical system.

2. The continuous zoom lens according to claim 1, characterized in that, The sampling points , In addition to the interval [a, b] satisfying the preset optimization constraints, it also includes: （1） in, Indicates machining precision; (2) The range Δ along the vertical optical axis remains unchanged after the external cam curves of the variable magnification group and the external cam curves of the compensation group are developed into planar curves before and after optimization; (3) The distance between adjacent sampling points of the planar curve developed by each outer cam curve in the direction perpendicular to the optical axis is greater than the accuracy of the zoom motor: in, Indicates the precision of the zoom motor; (4) The spacing between adjacent sampling points of the planar curve developed by each outer cam curve in the direction perpendicular to the optical axis satisfies: in, Indicates the weighting coefficient. The range is [1, 3]; （5） , Where D is the diameter of the pin. Indicates the weighting coefficient. The range is [1, 3]. The planar curve formed by the development of the external cam profile of the variable magnification group is about functions, The planar curve formed by the development of the outer cam curve of the compensation group is about The function.

3. The continuous zoom lens according to claim 1, characterized in that, The fitness function is: in, Indicates the pressure angle at the sampling point of the zoom group; Indicates the pressure angle at the sampling point of the compensation group; This represents the average pressure angle of the sampling points in the variable magnification group; This represents the average pressure angle at the sampling points of the compensation group; These represent the weighting coefficients for the zoom lens group and the compensation lens group, respectively.

4. The continuous zoom lens according to claim 1, characterized in that, The front fixed lens group includes a positive power cemented lens formed by cementing a first lens and a second lens together, and a positive power third lens. The zoom lens group includes a fourth lens with negative optical power and a cemented lens with negative optical power formed by cementing a fifth lens and a sixth lens together. The compensation lens group includes a positive optical power cemented lens formed by cementing the seventh and eighth lenses together, and a positive optical power ninth lens. The rear fixed lens group includes a tenth lens with negative optical power, an eleventh lens with positive optical power, a negative optical power cemented lens formed by cementing the twelfth and thirteenth lenses together, and a fourteenth lens with positive optical power. The distances between the front fixed group lens and the rear fixed group lens and the image plane are fixed, while the distances between the zoom group lens and the compensation group lens and the image plane in the optical axis direction are adjustable.

5. The continuous zoom lens according to claim 1, characterized in that, The continuous zoom lens has a focal length range of 20.00 mm to 159.95 mm and an F-number of 3.89 to 5.

80.

6. The continuous zoom lens according to claim 4, characterized in that, The first to the fourteenth lenses are all spherical glass lenses.

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