CN113655585B - Method for adjusting and detecting zoom imaging lens - Google Patents

Abstract

The invention provides an assembly and detection method of a zoom imaging lens, which solves the problems of low image quality, low assembly efficiency and repeated assembly and disassembly of the existing zoom lens caused by cam curve processing errors and moving lens group posture changes. The method is an assembly and simulation synchronous iteration adjustment method, the method obtains the variation of the posture of each moving lens group in the moving process, and the variation is subjected to optical simulation analysis to evaluate the lens transfer function and the visual axis jumping quantity, and meanwhile, the method can also measure the key part parameter cam curve of the zooming system, and can evaluate the performance of the imaging system more accurately.

Description

A method for adjusting and detecting a zoom imaging lens

technical field

The invention belongs to the field of zoom optical imaging, in particular to a method for assembling and detecting a zoom imaging lens.

Background technique

During the assembly process of the optical lens, it is necessary to ensure that the optical center of each lens glass is coaxial with the mechanical center. When each moving mirror group is static, the centering process can ensure that the optical center is coaxial with the mechanical axis. However, when the moving mirror group moves in the main lens barrel according to the cam curve, the posture of the moving mirror group will change due to the gap between the moving parts, and these changes in the posture will cause the boresight to be out of tolerance and the image plane to be consistent. performance deterioration and other problems, resulting in poor imaging image quality.

When the cam curve directly determines the focal length of the zoom imaging system, the relative position and relative position difference between the moving lens groups will directly affect the precise position of the image plane. Therefore, the machining accuracy of the cam curve also directly affects the image plane consistency of the zoom system. parameters, resulting in poor image quality. In the past, after image generation in the later stage, if the image quality is not high and the boresight axis jumps obviously, it is necessary to repeatedly disassemble and assemble the optical lens to find a solution. Therefore, the lens assembly efficiency is low, the whole process is complicated, time-consuming and laborious, and even repeated Disassembly and assembly many times does not solve the problem.

Chinese patent CN110954084A discloses a mobile mirror group attitude measurement device and measurement method. The method can measure the visual axis runout of the mobile mirror group and the change diagram of the system transfer function. However, the measurement data of the device is single and lacks the mobile mirror. The research on the error of the optical axis direction of the group is not accurate enough to evaluate the performance of the imaging system, and this method can only measure a single mirror group at a time. When measuring the second mirror group, the first mirror group needs to be removed. Displacement of stationary components may occur, affecting the results of the measurement.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problems of low image quality, low assembly efficiency and repeated disassembly and assembly of the existing zoom lens due to the processing error of the cam curve and the change of the attitude of the moving lens group, and provides a zoom imaging lens assembly. Tuning and detection methods. This method is an iterative method of assembling and simulating synchronously. Through this method, the change of the attitude of the moving mirror group during the movement is obtained, and through the optical simulation analysis of the change, the transfer function of the lens and the runout of the boresight are evaluated. At the same time, it can also measure the cam curve of the key parameter of the zoom system, which can more accurately evaluate the performance of the imaging system.

For realizing the above object of the invention, the technical scheme of the present invention is as follows:

A method for assembling and detecting a zoom imaging lens, comprising the following steps:

Step 1, build the installation and adjustment system;

The installation and adjustment system includes a first laser ranging theodolite, a second laser ranging theodolite, a first attitude adjustment platform, a second attitude adjustment platform, a lifting platform, a reference tool, a variable magnification group measurement tool and a compensation group measurement tool;

The first attitude adjustment platform is arranged under the first laser ranging theodolite, the second attitude adjustment platform is arranged under the second laser ranging theodolite, and the lifting platform is arranged under the zoom lens;

Step 2. Fix the zoom lens to avoid displacement change of the zoom lens;

The zoom lens includes a main lens barrel, a moving lens group, a zoom cam and a motor. The moving lens group is arranged in the main lens barrel and includes a variable magnification lens group and a compensation lens group. The motor drives the zoom cam to rotate, thereby driving The moving mirror group moves linearly along the axial direction in the main lens barrel;

Step 3: Install the reference tooling on the front end of the main lens barrel, and make the mechanical axis of the main lens barrel and the optical axis of the reference tooling coaxial;

Step 4: Adjust the postures of the first laser ranging theodolite and the second laser ranging theodolite so that the optical axes of the first laser ranging theodolite and the second laser ranging theodolite are coaxial with the optical axis of the reference tooling, and record the first The distance measurement values LA and LB of the laser ranging theodolite and the second laser ranging theodolite, then the distance between the first laser ranging theodolite and the second laser ranging theodolite is LA+LB+d, and d is the cross of the reference tooling The lens thickness of the silk reference plane mirror;

Step 5. Fix the attitude of the first laser ranging theodolite, the second laser ranging theodolite and the zoom lens, and record the reference value, then remove the reference tooling, and the reference value includes the reference angle attitude value and the reference offset attitude value;

Step 6. Install the zoom lens group and the compensation lens group into the main lens barrel, install the zoom group measurement tool on the front end of the zoom lens group, and install the mechanical axis of the zoom lens group and the optical axis of the zoom group measurement tool. Coaxial; install the compensation group measurement tool on the front end of the compensation lens group, and the mechanical axis of the compensation lens group is coaxial with the optical axis of the compensation group measurement tool;

Step 7. Set the zoom cam to the short focus position, drive the motor to the long focus position step by step, record the rotation angle of the zoom cam at each step, and record the first laser ranging theodolite and the second laser ranging theodolite corresponding to each step. The distance readings La and Lb of the zoom cam can be calculated to obtain the distance between the variable magnification lens group and the compensation lens group when the zoom cam rotates at each angle, which is equal to LA+LB+d-La-Lb-d2, thus fitting the zoom cam Curve, d2 is the reticle of the compensation group measuring tool to measure the lens thickness of the plane mirror;

Step 8. Compare the zoom cam curve obtained in step 7 with the cam design curve. If the difference is within the set threshold, perform step 8. If the difference exceeds the set threshold, correct the zoom cam until If the difference is within the set threshold, then go to step 8;

Step 9. Set the zoom lens cam to the short-focus position again, drive the motor to the long-focus position step by step, and record the variable magnification lens group and compensation mirror measured by the first laser rangefinder theodolite and the second laser rangefinder theodolite at each step. The attitude information reading of the group is compared, and the attitude information reading is compared with the reference value to obtain the angle attitude value and offset attitude value of the zoom lens group and the compensation lens group. At the same time, the measurement between the zoom lens group and the compensation lens group is obtained. distance, compare the measured distance with the theoretical distance between the variable magnification lens group and the compensation lens group, and obtain the difference Δd;

Step 10: Substitute the angular attitude value and offset attitude value of the variable magnification lens group and the compensation lens group and the difference Δd into the CodeV optical design software to obtain the amount of vibration and defocus of the system boresight.

Further, in step 7, the rotation angle of the zoom cam ranges from 0° to 60°, the rotation angle of the motor is 240°, and the drive step length of the motor is set to be 10°.

Further, scales are provided on the reticle measuring plane mirrors of the compensation group measuring tool and the variable magnification group measuring tool, and the accuracy is at least 0.003 mm.

Compared with the prior art, the technical solution of the present invention has the following advantages:

1. The method of the present invention measures and evaluates the moving posture of each moving mirror group before the optical lens is installed, and simultaneously measures the machining accuracy of the cam curve, which can avoid repeated disassembly in the assembly process and improve assembly efficiency.

2. The method of the present invention measures the machining accuracy of the cam curve in advance, and corrects the cam curve by comparing the measured value with the design value, so that the error of the moving mirror group moving along the optical axis can be reduced, and more accurate Evaluate imaging system performance.

3. The method of the present invention adopts two theodolites, which can measure the attitudes of the variable magnification group and the compensation group at the same time, avoiding the dismantling steps between different mirror groups, and the position of the fixed part of each mirror group will not change, which improves the measurement results.

4. The device adopted in the method of the present invention has the advantages of simple structure, easy operation, simple control and high measurement accuracy, and higher-precision measurement results can be obtained by reducing the driving step of the driving motor.

5. The method of the present invention adopts tooling with low processing cost, simple assembly and testing, and can be widely used in the assembly process of various zoom lenses by designing different toolings.

Description of drawings

1 is a schematic structural diagram of an existing zoom lens;

Fig. 2 is the schematic diagram when the reference tooling is adjusted in the method of the present invention;

Fig. 3 is the schematic diagram of the variable magnification group measuring tool during the adjustment in the method of the present invention;

4 is a schematic diagram of the compensation group measurement tooling during the adjustment in the method of the present invention;

Fig. 5a is the structural representation of the reference tooling in the present invention;

Figure 5b is a schematic diagram of a reference tool and its centering in the present invention;

6a is a schematic structural diagram of a crosshair measuring tool in the present invention;

Figure 6b is a schematic diagram of the crosshair measuring tool and its centering in the present invention;

7 is a schematic diagram of the assembly relationship between the main lens barrel, the mobile lens group, and the crosshair tooling in the present invention;

8a is a schematic diagram 1 of the motion relationship between the variable magnification mirror group and the compensation mirror group according to the method of the present invention;

8b is a schematic diagram 2 of the motion relationship between the variable magnification mirror group and the compensation mirror group according to the method of the present invention;

Fig. 8c is a schematic diagram 3 of the motion relationship between the variable magnification lens group and the compensation lens group according to the method of the present invention.

Reference signs: 1-first laser ranging theodolite, 2-second laser ranging theodolite, 3-reference tooling, 4-zoom lens, 5-first attitude adjustment platform, 6-second attitude adjustment platform, 7- Lifting table, 8-zoom group measurement tooling, 9-compensation group measurement tooling, 10-multiplier mirror; 31-reference mirror frame, 32-reference pressure ring, 33-crosshair reference plane mirror, 41-main lens barrel, 42- Moving lens group, 43- Zoom cam, 44- Motor, 45- Feedback potentiometer, 46- Motor control circuit board, 47- Zoom lens barrel, 48- Compensation lens barrel, 81- Measuring frame, 82- Measuring pressure Circle, 83 - Crosshair measuring plane mirror.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention, and are not intended to limit the protection scope of the present invention.

As shown in FIG. 1, the existing zoom imaging lens (ie zoom lens 4) includes a main lens barrel 41, a moving lens group 42, a zoom cam 43, a motor 44, a feedback potentiometer 45 and a motor control circuit board 46; the moving lens group 42 is arranged in the main lens barrel 41, including a variable magnification lens group and a compensation lens group, the variable magnification lens group includes a variable magnification lens barrel 47 and a variable magnification lens set in the variable magnification lens barrel 47, and the compensation lens group includes a compensation lens barrel 48 and the compensation lens arranged in the compensation lens barrel 48, the zoom cam 43 is installed on the outer periphery of the main lens barrel 41; the motor control circuit board 46 controls the motor 44 to drive the zoom cam 43 to rotate, thereby driving the moving lens group 42 in the main lens barrel 41. Do linear motion along the axial direction; the feedback potentiometer 45 is used to feedback the position of the moving mirror group 42 .

The invention provides a method for adjusting and detecting the above zoom imaging lens, and the method is specifically a method for measuring the image plane consistency, the debugging of the visual axis runout and the precision of the zoom cam curve of the key component during the adjusting process of the zoom lens. This method measures the posture of the moving lens group before the optical lens is installed, and compares and iterates the measurement parameters with the design parameters, simulates and analyzes the image plane consistency and boresight jitter problems of the zoom optical lens, and seeks solutions in advance to avoid Repeated disassembly during final assembly improves assembly efficiency.

As shown in FIG. 2 to FIG. 4 , the adjustment and detection method of the zoom imaging lens of the present invention is realized based on the adjustment system. The installation and adjustment system includes a first laser ranging theodolite 1, a second laser ranging theodolite 2, a first attitude adjustment platform 5, a second attitude adjustment platform 6, a lifting platform 7, a reference tooling 3, a variable magnification group measuring tooling 8, Compensation group measuring tool 9. The first attitude adjustment platform 5 and the second attitude adjustment platform 6 can both be three-point attitude adjustment platforms. The eyepieces of the first laser ranging theodolite 1 and the second laser ranging theodolite 2 are provided with a magnifying mirror 10 .

The above-mentioned first laser ranging theodolite 1 and second laser ranging theodolite 2 are attitude information measuring instruments of the variable magnification mirror group and the compensation mirror group, and are used to measure the attitude of the variable magnification mirror group and the compensation mirror group. The first attitude adjustment platform 5 is arranged below the first laser ranging theodolite 1 for adjusting the attitude of the first laser ranging theodolite 1, and the second attitude adjustment platform 6 is arranged below the second laser ranging The attitude of the theodolite 2 is adjusted. The zoom lens 4 is the object of action, and the lifting platform 7 is arranged below the zoom lens 4 to adjust the posture of the zoom lens 4; the reference tooling 3 is installed at the front end of the main lens barrel 41 to provide the first laser ranging theodolite 1, The measurement reference of the second laser ranging theodolite 2, the variable magnification group measuring tool 8 is installed at the front end of the variable magnification mirror group, and is used to transfer the attitude information of the variable magnification mirror group to the variable magnification group measurement tool 8 for measurement, and the compensation group measurement The tooling 9 is installed at the front end of the compensation mirror group, and is used for transferring the attitude information of the compensation mirror group to the measurement tooling 9 of the compensation group for measurement.

As shown in FIGS. 5 a and 5 b , the reference tooling 3 of the present invention includes a reference mirror frame 31 , a reference pressure ring 32 and a crosshair reference plane mirror 33 . The reticle reference plane reflector 33 is installed in the reference mirror frame 31 with glue, fixed by the reference pressure ring 32, and the centering treatment is performed after the glue is completely dry. The reference tooling 3 uses the optical center of the crosshair reference plane mirror 33 as the benchmark to measure the diameter of the inner hole at the front end of the main lens barrel 41. The dimension B of the reference mirror frame 31 is matched with the inner hole at the front end of the main lens barrel 41 to ensure that the unilateral gap is not greater than 0.01mm, process D of the reference mirror frame 31 to ensure that its concentricity with reference A is not greater than 0.01mm; process the reference mirror frame 31E to ensure that its perpendicularity to reference A is not greater than 0.01mm. The blue is cut, and the centering of the reference tooling 3 is completed at this time.

As shown in Figures 6a and 6b, the variable magnification group measuring tool 8 includes a measuring mirror frame 81, a measuring pressure ring 82, and a reticle measuring plane mirror 83 with a scale and an accuracy of 0.003mm. The measuring mirror frame 81 is provided with 4 countersunk holes for installing M1.6 screws, and the 4 countersunk holes are evenly distributed. The reticle measuring plane reflection mirror 83 is installed on the measuring mirror frame 81 with glue, and is fixed by the measuring pressure ring 82. After the glue dries, the centering treatment is performed. The variable magnification group measuring tool 8 takes the optical center of the crosshair measuring plane mirror 83 as the benchmark, measures the inner hole diameter of the variable magnification lens barrel 47, and measures the dimension B of the mirror frame 81 and the inner hole of the variable magnification lens barrel 47. The unilateral gap is not greater than 0.01mm; the D position of the measurement frame 81 is processed to ensure that its concentricity with the reference A is not greater than 0.01mm; the E position of the measurement frame 81 is processed to ensure that its perpendicularity to the reference A is not greater than 0.01 mm; cut off the flange along C, at this time, the centering of the measuring tool 8 of the zoom group is completed.

Compensation group measuring tool 9 has the same structure as variable magnification group measuring tool 8, including measuring frame, measuring pressure ring, cross-hair measuring plane mirror; Compensate the diameter of the inner hole of the lens barrel 48, and measure the size B of the mirror frame and match the inner hole of the compensation lens barrel 48 to ensure that the unilateral gap is not greater than 0.01mm; process the D position of the measurement frame to ensure that it is concentric with the reference A Not more than 0.01mm; process the E part of the measuring frame to ensure that its perpendicularity to the reference A is not more than 0.01mm; cut off the flange along the C part, at this time, the centering of the measurement tool 9 of the compensation group is completed.

Based on the above system and device, the present invention provides a method for adjusting and detecting a zoom imaging lens, comprising the following steps:

Step 1, build the above installation and adjustment system;

Step 2, fixing the zoom lens 4 on the lifting platform 7, and fixing the lifting platform 7 to avoid the displacement change of the zoom lens 4;

Step 3. As shown in FIG. 7, since the main lens barrel 41 of the zoom lens 4 can ensure that the coaxiality between the inner circle of the focusing part and the inner circle of the variable magnification part is not greater than 1 wire during the processing, it can be considered that the main lens barrel is The front and rear ends of the mechanical axis of 41 are coaxial, and the reference tooling 3 is installed at the front end of the main lens barrel 41, and the mechanical axis of the main lens barrel 41 is drawn out, and the mechanical axis of the main lens barrel 41 is coaxial with the optical axis of the reference tooling 3;

Step 4: Adjust the postures of the first laser ranging theodolite 1 and the second laser ranging theodolite 2 so that the optical axes of the first laser ranging theodolite 1 and the second laser ranging theodolite 2 are coaxial with the optical axis of the reference tool 3, And record the distance measurement values LA and LB of the first laser ranging theodolite 1 and the second laser ranging theodolite 2, and the thickness of the lens of the crosshair reference plane mirror 33 of the reference tooling 3 is d, then the first laser ranging theodolite 1 , the distance between the second laser ranging theodolite 2 is LA+LB+d, as shown in Figure 8a;

Step 5: Fix the postures of the first laser ranging theodolite 1, the second laser ranging theodolite 2 and the zoom lens 4, and record the reference value before removing the reference tool 3. The reference value refers to the reference tool reticle, the first laser ranging The deviation between the theodolite reticle and the second laser ranging theodolite reticle passing through the reflection image of the reference tooling, the deviation between the theodolite reticle and the reflection image is the reference angle attitude value, and the deviation between the theodolite reticle and the reference tooling reticle As the reference offset attitude value, since the optical axis of the second laser ranging theodolite and the first laser ranging theodolite and the optical axis of the reference tooling have been adjusted to the same axis in the early stage, the reference angle attitude value and the reference offset attitude value are both 0 ;

Step 6. Install the variable magnification lens group and the compensation lens group into the main lens barrel 41. Since the outer diameter of the variable magnification lens barrel 47 and the compensation lens barrel 48 and the coaxiality of their inner holes are not greater than 1 wire, it can be considered that they are the same. axis. As shown in Figure 3, install the zoom group measurement tool 8 on the front end of the zoom lens group, fix it with 4 M1.6 countersunk head screws, and lead out the mechanical axis of the zoom lens group, and the mechanical axis of the zoom lens group Coaxial with the optical axis of the zoom group measurement tool 8; as shown in Figure 4, install the compensation group measurement tool 9 on the front end of the compensation lens group, fix it with 4 M1.6 countersunk head screws, and lead out the mechanical axis of the compensation lens group , and the mechanical axis of the compensation lens group is coaxial with the optical axis of the compensation group measurement tool 9;

Step 7, the drive motor 44 works, the zoom cam 43 is moved to the short focal length position, and the short focal length position of the zoom lens 4 is used as the starting point to drive the motor 44 step by step to the long focal position, and the rotation angle of the zoom cam 43 is recorded at each step, and The rotation angle of each step corresponds to the corresponding focal length value of the zoom lens 4, and the distance readings La and Lb of the first laser ranging theodolite 1 and the second laser ranging theodolite 2 are recorded at each step, so that the different rotations of the zoom cam 43 are calculated. The distance between the variable magnification lens group and the compensation lens group at the angle (that is, at each focal length value of the zoom lens 4), so as to fit the zoom cam 43 curve. Cam curve machining accuracy;

During the test, the focal length of the zoom lens 4 is in the range of 24mm to 120mm, the pixel size is 3.45um, the rotation angle of the motor 44 is 240°, the drive step of the motor 44 is set to 10°, and the rotation angle of the zoom cam 43 is in the range of 0 to 60°. °, since the gear ratio of the motor 44 and the zoom cam 43 is 4:1, the rotation step of the zoom cam 43 is 2.5°. During the rotation of the zoom cam 43 from 0° to 60°, the focal length of the zoom lens 4 changes from the short focus 24mm changes to telephoto 120mm state, but the change of focal length changes non-linearly. Taking the angle value as the abscissa, and taking the angle of each step of the zoom cam 43, the position information of the zoom lens group and the compensation lens group is the ordinate, and the curve is drawn. , the obtained curve is the measurement fitting curve of the cam curve, and comparing the fitting curve with the design curve, the machining accuracy of the cam curve can be obtained;

For example, taking the position of the first laser ranging theodolite 1 as zero, the movement position of the compensation mirror group is converted into data. The schematic diagram of the position conversion is shown in Figure 8b and Figure 8c: the position information of the compensation mirror group relative to the first laser ranging theodolite 1: LA+LB+d-Lb-d2, where LA=150mm, LB=200mm, d=d2=2mm; the position information of the variable magnification mirror group relative to the first laser ranging theodolite 1: La, at this time, the variable magnification can be obtained The distance between the mirror group and the compensation mirror group is LA+LB+d-La-Lb-d2;

The following table is obtained after converting the position measurement data of the compensation lens group and the variable magnification lens group by the above formula:

Step 8. Use EXCEL to draw the cam detection value curve, and compare it with the cam design value curve. If the difference is within the set threshold, perform step 8. If the difference exceeds the set threshold, the zoom cam 43 Make corrections until the difference is within the set threshold, and then perform step 8;

From the comparison results, the trend of the cam curve detection parameters is consistent with the theoretical design trend, and the maximum deviation is not greater than 8 wires, and the curve processing accuracy meets the requirements.

Step 9. Set the cam curve of the zoom lens 4 at the short focus position, drive the motor 44 to the long focus position step by step, and record the zoom mirrors measured by the first laser ranging theodolite 1 and the second laser ranging theodolite 2 at each step. The attitude information readings of the group and the compensation mirror group are compared, and the attitude information readings are compared with the reference values, and the difference values θ _X , θ _Y , d _{X ,} , and d _Y are obtained, and the difference values are the angle attitude value and offset attitude value. , at the same time, the difference Δd between the measured distance and the theoretical distance between the variable magnification lens group and the compensation lens group can be obtained;

Before the measurement, the optical axes of the first laser ranging theodolite 1 and the second laser ranging theodolite 2 have been adjusted to coincide with the optical axis of the zoom lens 4, so the reference value is (0,0,0,0), where The first two 0 values refer to the reference angle attitude value, and the last two 0 values refer to the reference offset attitude value;

A multiplier 10 is installed at the eyepieces of the first laser ranging theodolite 1 and the second laser ranging theodolite 2. Starting from a short focus, the motor 44 is driven step by step, and each step corresponds to a corresponding focal length value to adjust the first laser Ranging theodolite 1 and the second laser ranging theodolite 2, make the optical axis of the theodolite and the optical axis of the moving mirror group 42 coaxial, at this time record the readings of the first laser ranging theodolite 1 and the second laser ranging theodolite 2, and compare them with the reference The angle and attitude values are compared, and the angle deviation of the X axis and the angle deviation of the Y axis are measured, that is, the angle and attitude value of the moving mirror group 42 is obtained;

Adjust the focal lengths of the first laser ranging theodolite 1 and the second laser ranging theodolite 2 to ensure that the measuring tool crosshair with a scale has a clear image, and record the variable magnification group measuring tool crosshair and the first laser ranging theodolite 1 at each step The X-axis offset and Y-axis offset between the reticle, and the X-axis offset and Y-axis offset between the reticle of the compensation group measurement tool and the second laser ranging theodolite 2 reticle at each step are recorded at the same time. Shift amount, by comparing with the reference value, the X-axis offset/Y-axis offset can be obtained, and then the offset attitude value of the zoom lens group and the offset attitude value of the compensation lens group can be obtained;

At the same time, the difference Δd between the measured distance and the theoretical distance between the time-variable magnification lens group and the compensation lens group with different step lengths is obtained, and different step lengths correspond to different focal lengths;

The measurement distance between the zoom lens group and the compensation lens group is: L _A +L _B +dL _a -L _b -d ₂

Attitude measurement data of zoom lens group:

Compensation lens group attitude measurement data:

Step 10. Substitute the angular attitude value, offset attitude value of the zoom lens group and the compensation lens group, the difference Δd between the measured distance and the theoretical distance between the zoom lens group and the compensation lens group into the CodeV optical design software to obtain the system Boresight runout, defocus amount; as shown in the following table:

From the optical fitting results, the maximum defocus amount is 1 wire, which will not have much impact on the imaging quality within the focal depth range of the imaging system. The visual axis jumps up to 2.3 pixels in the Y direction, which can meet the index requirements.

In the prior art, only the influence of the attitude change of the moving mirror group on the visual axis beating and the imaging quality is concerned, but the movement error Δd of the moving mirror group along the optical axis direction is not measured, and this error will also affect the visual axis beating and the imaging quality. , the method of the invention measures the movement error of the moving lens group along the optical axis direction of the different focal length points through two theodolites that can measure distance, so that the performance of the imaging system can be evaluated more accurately. The movement error of the moving mirror group along the optical axis is mainly related to the machining accuracy of the cam curve. Therefore, the method of the present invention measures the machining accuracy of the cam curve in advance. The imaging system will not produce good imaging performance, so the cam curve needs to be corrected before use; if it is found that there is little difference between the measured value and the design value, the difference can be combined with the attitude error information of the moving mirror group Bring into the code software for simulation analysis.

The method of the invention adopts two theodolites, which can measure the postures of the variable magnification group and the compensation group at the same time, avoids the dismantling steps between different mirror groups, and the position of the fixed part of each mirror group does not change, thereby improving the measurement performance. result.

The method of the invention has the advantages of simple structure, easy operation, simple control and high measurement accuracy, and can obtain higher-precision measurement results by reducing the motor driving step.

The tooling of the method of the invention has low processing cost, simple assembly and testing, and can be widely used in the assembly process of various zoom lenses by designing different toolings.

Through the measuring method of the present invention, the moving posture of each moving mirror group is measured and evaluated before the optical frame is inserted, and the machining accuracy of the cam curve is measured at the same time, which can avoid repeated disassembly in the final assembly process and improve the assembly efficiency.

Claims (3)

1. a method for assembling and detecting a zoom imaging lens, is characterized in that, comprises the following steps: Step 1, build the installation and adjustment system; The installation and adjustment system includes a first laser ranging theodolite, a second laser ranging theodolite, a first attitude adjustment platform, a second attitude adjustment platform, a lifting platform, a reference tool, a variable magnification group measurement tool and a compensation group measurement tool; The first attitude adjustment platform is arranged under the first laser ranging theodolite, the second attitude adjustment platform is arranged under the second laser ranging theodolite, and the lifting platform is arranged under the zoom lens; Step 2. Fix the zoom lens to avoid displacement change of the zoom lens; The zoom lens includes a main lens barrel, a moving lens group, a zoom cam and a motor. The moving lens group is arranged in the main lens barrel and includes a variable magnification lens group and a compensation lens group. The motor drives the zoom cam to rotate, thereby driving The moving mirror group moves linearly along the axial direction in the main lens barrel; Step 3: Install the reference tooling on the front end of the main lens barrel, and make the mechanical axis of the main lens barrel and the optical axis of the reference tooling coaxial; Step 4: Adjust the postures of the first laser ranging theodolite and the second laser ranging theodolite so that the optical axes of the first laser ranging theodolite and the second laser ranging theodolite are coaxial with the optical axis of the reference tooling, and record the first The distance measurement values LA and LB of the laser ranging theodolite and the second laser ranging theodolite, then the distance between the first laser ranging theodolite and the second laser ranging theodolite is LA+LB+d, and d is the cross of the reference tooling The lens thickness of the silk reference plane mirror; Step 5. Fix the attitude of the first laser ranging theodolite, the second laser ranging theodolite and the zoom lens, and record the reference value, then remove the reference tooling, and the reference value includes the reference angle attitude value and the reference offset attitude value; Step 6. Install the zoom lens group and the compensation lens group into the main lens barrel, install the zoom group measurement tool on the front end of the zoom lens group, and install the mechanical axis of the zoom lens group and the optical axis of the zoom group measurement tool. Coaxial; install the compensation group measurement tool on the front end of the compensation lens group, and the mechanical axis of the compensation lens group is coaxial with the optical axis of the compensation group measurement tool; Step 7. Set the zoom cam to the short focus position, drive the motor to the long focus position step by step, record the rotation angle of the zoom cam at each step, and record the first laser ranging theodolite and the second laser ranging theodolite corresponding to each step. The distance readings La and Lb of the zoom cam can be calculated to obtain the distance between the variable magnification lens group and the compensation lens group when the zoom cam rotates at each angle. The distance value is LA+LB+d-La-Lb-d2, and then fit Zoom cam curve, d2 is the crosshair of the compensation group measuring tool to measure the lens thickness of the plane mirror; Step 8. Compare the zoom cam curve obtained in step 7 with the cam design curve. If the difference is within the set threshold, perform step 8. If the difference exceeds the set threshold, correct the zoom cam until The difference is within the set threshold, then go to step 8; Step 9. Set the zoom lens cam to the short-focus position again, drive the motor to the long-focus position step by step, and record the variable magnification lens group and compensation mirror measured by the first laser rangefinder theodolite and the second laser rangefinder theodolite at each step. The attitude information reading of the group is compared, and the attitude information reading is compared with the reference value to obtain the angle attitude value and offset attitude value of the zoom lens group and the compensation lens group, and at the same time, the measurement between the zoom lens group and the compensation lens group is obtained. distance, compare the measured distance with the theoretical distance between the variable magnification lens group and the compensation lens group, and obtain the difference Δd; Step 10. Substitute the angular attitude value and offset attitude value of the zoom lens group and the compensation lens group and the difference Δd into the CodeV optical design software to obtain the bosom jitter and defocus amount of the zoom lens. 2 . The method for adjusting and detecting a zoom imaging lens according to claim 1 , wherein in step 7, the rotation angle of the zoom cam ranges from 0 to 60°, and the rotation angle of the motor is 240° 2. 3 . °, set the drive step of the motor to 10°. 3. The method for assembling and detecting a zoom imaging lens according to claim 1 or 2, characterized in that: scales are provided on the reticle measuring plane mirrors of the compensation group measuring tool and the variable magnification group measuring tool, And the accuracy is at least 0.003mm.

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