High-zoom-ratio continuous zoom lens for interference image acquisition

Abstract

The invention provides a high-zoom-ratio continuous zoom lens for interference image acquisition, and relates to the technical field of optical imaging. Comprising a first lens group with positive focal power, a second lens group with negative focal power, a third lens group with positive focal power, a fourth lens group with negative focal power and a fifth lens group with positive focal power which are sequentially arranged from an object space to an image space along an optical axis. According to the high-resolution sampling lens, the focal length can be continuously changed from 14.31 mm to 127.84 mm in cooperation with a collimating lens with a certain focal length, the zoom ratio is 8.93, and therefore high-resolution sampling of interference images is achieved. The invention has the characteristics of low distortion, small volume, compact structure and the like.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, specifically to a high-magnification continuous zoom lens for interferometric image acquisition. Background Technology

[0002] Continuous zoom lenses are lenses whose focal length can be continuously adjusted within a certain range. With the continuous development of machine vision and industrial automation, continuous zoom lenses have been used more and more widely.

[0003] Currently, there are two types of continuous zoom lenses on the market: those with a constant working distance and those with a variable working distance. As zoom lenses used for interferometric image acquisition within interferometers, those with a constant working distance, when paired with a collimating lens of a specific focal length, can acquire interferometric images at different magnifications. Current continuous zoom lenses for interferometric image acquisition typically have a zoom range of 0.7-4.5x, a focal length variation of 13.36mm-85.86mm, and a zoom ratio of 6.43. To improve the resolution of interferometric fringe, current cameras used for interferometric image acquisition use smaller detector pixels and larger arrays; therefore, the focal length range of existing camera zoom lenses is insufficient to meet current application requirements. Summary of the Invention

[0004] Therefore, in order to solve the above problems, the present invention provides a high zoom ratio continuous zoom lens for interferometric image acquisition, which realizes a continuous change in focal length from 14.31mm to 127.84mm, and the zoom ratio reaches 8.93.

[0005] This invention provides a high-magnification continuous zoom lens for interferometric image acquisition, mainly comprising: along the optical axis from the object side to the image side, the following components are sequentially included:

[0006] The first lens group includes a first biconvex lens and a first meniscus lens, which are cemented together to form a first cemented mirror, and a second biconvex lens and a first biconcave lens, which are cemented together to form a second cemented mirror, arranged sequentially from the object side to the image side.

[0007] The second lens group includes a second meniscus lens and a second biconcave lens, which are cemented together to form a third cemented lens and are disposed from the object side to the image side.

[0008] The third lens group includes a third meniscus lens and a third biconvex lens that are cemented together to form a fourth cemented lens and are arranged from the object side to the image side;

[0009] The fourth lens group includes a third biconcave lens and a fourth biconvex lens that are cemented together to form a fifth cemented lens and are arranged from the object side to the image side;

[0010] The fifth lens group includes a fifth biconvex lens and a fourth meniscus lens, which are cemented together to form a sixth cemented lens, arranged sequentially from the object side to the image side; and a fifth meniscus lens and a sixth meniscus lens, which are cemented together to form a seventh cemented lens.

[0011] Furthermore, it also includes an aperture, located between the third and fourth cemented lenses;

[0012] Furthermore, the object-facing surfaces of the first, second, and fourth meniscus lenses are concave, while the object-facing surfaces of the meniscus lenses in the other cemented lenses are convex.

[0013] Furthermore, the second and fourth lens groups can be moved along the optical axis to adjust the air gap between them and the front and rear lens groups.

[0014] Furthermore, the air gap between the first lens group and the second lens group is 10.23mm~40.23mm, the air gap between the second lens group and the third lens group is 10.12mm~40.13mm, the air gap between the third lens group and the fourth lens group is 10mm~39.95mm, and the air gap between the fourth lens group and the fifth lens group is 10mm~40mm.

[0015] The present invention has the following advantages over the prior art:

[0016] 1. This invention provides a high-magnification continuous zoom lens for interferometric image acquisition. It comprises a first lens group with positive optical power, a second lens group with negative optical power, a third lens group with positive optical power, a fourth lens group with negative optical power, and a fifth lens with positive optical power, arranged sequentially along the optical axis from the object side to the image side. Combined with a collimating lens of a certain focal length, it can achieve a continuous change in focal length from 14.31 mm to 127.84 mm, with a zoom ratio of 8.93, thereby achieving high-resolution sampling of interferometric images. This lens also features low distortion, small size, and compact structure.

[0017] 2. This invention provides a high-magnification continuous zoom lens for interferometric image acquisition. It employs four lens groups: the first four lens groups are used for zoom adjustment, the fifth lens group is used to balance aberrations, and continuous zoom adjustment is achieved by adjusting the air gaps between the second and fourth lens groups and the lens groups preceding and following them. An aperture stop is used to control the amount of light and to select the position of a point imaging beam outside the optical axis.

[0018] 3. Specifically designed for the magnification requirements of interferometers, and when used with a collimating lens of a certain focal length, the magnification range can reach 0.75. × - 6.7 ×With a zoom ratio of 8.93x, this design better meets the diverse imaging magnification requirements of interferometers in different measurement scenarios. Furthermore, the lens features low distortion, high resolution, small size, and low cost. This zoom lens has a magnification range of 0.75x to 6.7x, a numerical aperture range of 0.055-0.12, is matched with a 1 / 2'' target sensor, has a maximum optical aperture of less than 24mm, a total optical length of 157.352mm from the first lens to the image plane, an operating wavelength of 632.8nm, and a focal length between 14.31mm and 127.84mm. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the continuous zoom lens of the present invention;

[0021] Figure 2 for Figure 1 A schematic diagram illustrating the application of a continuous zoom lens based on a Fizeau interferometer.

[0022] Figure 3 for Figure 1 A schematic diagram of the optical path of a continuous zoom lens at different magnifications;

[0023] Figure 4 for Figure 1 The continuous zoom lens in the 0.75 × A point-by-point chart;

[0024] Figure 5 for Figure 1 The continuous zoom lens in 3 × A point-by-point chart;

[0025] Figure 6 for Figure 1 The continuous zoom lens in 5 × A point-by-point chart;

[0026] Figure 7 for Figure 1 The continuous zoom lens in 6.7 × A point-by-point chart;

[0027] Figure 8 for Figure 1 The continuous zoom lens in the 0.75 ×The MTF curve;

[0028] Figure 9 for Figure 1 The continuous zoom lens in 3 × The MTF curve;

[0029] Figure 10 for Figure 1 The continuous zoom lens in 5 × The MTF curve;

[0030] Figure 11 for Figure 1 The continuous zoom lens in 6.7 × The MTF curve;

[0031] Figure 12 for Figure 1 The continuous zoom lens in the 0.75 × Field curvature and distortion curves;

[0032] Figure 13 for Figure 1 The continuous zoom lens in 3 × Field curvature and distortion curves;

[0033] Figure 14 for Figure 1 The continuous zoom lens in 5 × Field curvature and distortion curves;

[0034] Figure 15 for Figure 1 The continuous zoom lens in 6.7 × Field curvature and distortion curves;

[0035] Figure 16 for Figure 1 A schematic diagram of the cam curve of a continuous zoom lens.

[0036] Explanation of reference numerals in the attached figures:

[0037] 1. First cemented lens; 11. First biconvex lens; 12. First meniscus lens; 2. Second cemented lens; 21. Second biconvex lens; 22. First biconcave lens; 3. Third cemented lens; 31. Second meniscus lens; 32. Second biconcave lens; 4. Fourth cemented lens; 41. Third meniscus lens; 42. Third biconvex lens; 5. Fifth cemented lens; 51. Third biconcave lens; 52. Fourth biconvex lens; 6. Sixth cemented lens; 61. Fifth biconvex lens; 62. Fourth meniscus lens; 7. Seventh cemented lens; 71. Fifth meniscus lens; 72. Sixth meniscus lens; 8. Aperture stop; 9. Laser; 10. Beam splitter; 13. Beam expander; 14. Collimating lens; 15. Planar optical disc; 16. Reference lens; 17. Object under test; 18. Beam splitter; 19. Collimating lens. Detailed Implementation

[0038] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] Example 1

[0040] Reference Figure 1 This invention provides a high-magnification continuous zoom lens for interferometric image acquisition, comprising, along the optical axis from the object side to the image side, the following components in sequence:

[0041] The first lens group includes lenses from the object side to the image side, i.e. Figure 1 From left to right along the optical axis, the first biconvex lens 11 and the first meniscus lens 12 of the cemented first cemented mirror 1, and the second biconvex lens 21 and the first biconcave lens 22 of the cemented second cemented mirror 2 are arranged sequentially.

[0042] The second lens group includes a second meniscus lens 31 and a second biconcave lens 32, which are cemented together to form a third cemented mirror 3 and are disposed from the object side to the image side.

[0043] The third lens group includes a third meniscus lens 41 and a third biconvex lens 42, which are cemented together to form a fourth cemented mirror 4 from the object side to the image side.

[0044] The fourth lens group includes a third biconcave lens 51 and a fourth biconvex lens 52, which are cemented together to form a fifth cemented mirror 5 and are disposed from the object side to the image side.

[0045] The fifth lens group includes a fifth biconvex lens 61 and a fourth meniscus lens 62, which are cemented together to form a sixth cemented mirror 6, arranged sequentially from the object side to the image side, and a fifth meniscus lens 71 and a sixth meniscus lens 72, which are cemented together to form a seventh cemented mirror 7.

[0046] Aperture 8 is located between the third cemented lens 3 and the fourth cemented lens 4;

[0047] The object-facing surfaces of the first meniscus lens 12, the second meniscus lens 31, and the fourth meniscus lens 62 are concave, while the object-facing surfaces of the meniscus lenses in the other cemented lenses are convex.

[0048] The second and fourth lens groups can be moved along the optical axis to adjust the air gap between them and the front and rear lens groups.

[0049] In this embodiment, four lens groups are used. The first four lens groups are used for zoom adjustment, and the fifth lens group is used to balance aberrations. Continuous zoom adjustment is achieved by adjusting the air gaps between the second and fourth lens groups and the lens groups before and after them. The aperture stop is used to control the amount of light and to select the position of the point imaging beam outside the optical axis.

[0050] In this embodiment, an adjustment of 0.75 is provided as an example. × ~6.7 × The air distance adjustment range for magnification is limited to adjusting the air distance between the second and fourth lens groups and the lens groups before and after them, while keeping the other lens groups fixed. The air distance d1 between the first and second lens groups is 13.25mm to 43.26mm, the air distance d2 between the second and third lens groups is 10mm to 40mm, the air distance d3 between the third and fourth lens groups is 10mm to 40mm, and the air distance d4 between the fourth and fifth lens groups is 10mm to 40mm. The focal length f1 of the first lens group is 90.48mm, the focal length f2 of the second lens group is -15.05mm, the focal length f3 of the third lens group is 24.57mm, the focal length f4 of the fourth lens group is -24.66mm, and the focal length f5 of the fifth lens group is 27.54mm.

[0051] Example 2

[0052] This embodiment demonstrates the application of this continuous zoom lens in interferometer testing. Figure 2 This is a schematic diagram. The laser emitted by laser 9 is first transmitted downwards, then split by beam splitter prism 10, and then passes sequentially through beam expander 13, aperture 8, and collimating lens 14 before reaching plane flat crystal 15. At this point, the beam splits into two paths: one path is reflected by reference mirror 16 to form reference light, and the other path passes through reference mirror 16 and is reflected by the object under test 17 to form test light. When the reference light and the test light meet, they interfere, and the resulting interference beam is transmitted to beam splitter 18 and split again: one beam is received to the right by CCD 1 to obtain a star image; the other beam passes downwards through collimating lens 19 and continuous zoom lens before being received by CCD 2 to obtain interference fringes. The continuous zoom lens can achieve clear imaging at different magnifications, meeting the interferometer's observation requirements for different fields of view and different magnifications during the detection process.

[0053] Here we take a low magnification of 0.75. × The middle multiple is 3 × The maximum magnification is 5. × The highest multiple is 6.7. × Let's take an example to analyze aberrations.

[0054] Dot plots at different magnifications are as follows Figures 4-7 As shown, where Figure 4The magnification is 0.75. × Point chart at time, Figure 5 The magnification is 3 × Point chart at time, Figure 6 The magnification is 5 × Point chart at time, Figure 7 The magnification is 6.7. × The dot plot is shown in the image. Overall, the dot plot size is relatively small, with the RMS diameter basically controlled within 11μm, which meets the resolution requirements of the image sensor.

[0055] MTF curves at different magnifications are as follows Figures 8-11 As shown, overall, the MTF curves for all magnifications are relatively smooth. Figure 8 As shown, the magnification is 0.75. × The MTF of the continuous zoom lens is greater than 0.3 at 113 lp / mm. For example... Figure 9 As shown, the magnification is 3. × The MTF of a continuous zoom lens is generally greater than 0.3 at 113 lp / mm. For example... Figure 10 As shown, the magnification is 5. × The MTF of the continuous zoom lens is greater than 0.2 at 113 lp / mm. For example... Figure 11 As shown, the magnification is 6.7. × The MTF of the continuous zoom lens is greater than 0.2 at 113 lp / mm.

[0056] Field curvature and distortion curves at different magnifications are as follows: Figures 12-15 As shown, where Figure 12 The magnification is 0.75. × Field curvature and distortion curves at time, Figure 13 The magnification is 3 × Field curvature and distortion curves at time, Figure 14 The magnification is 5 × Field curvature and distortion curves at time, Figure 15 The magnification is 6.7. × The field curvature and distortion curves are shown. Overall, the distortion is relatively small, with the maximum distortion basically controlled within 1.1%.

[0057] like Figure 16As shown, curves y1 and y2 reflect the motion trajectories of the second and fourth lens groups along the optical axis, respectively. The second lens group moves in a straight line, while the fourth lens group moves in a curved path. In the cam curve corresponding to the fourth lens group, the maximum pressure rise angle occurs at the beginning of the curve, with a value of approximately 45.53°. This design avoids problems such as jamming and impact caused by excessive pressure rise angle during continuous zooming, thereby improving the stability, response speed, and long service life of the lens zoom operation.

[0058] Table 1 shows the parameters of each lens element in the continuous zoom lens, and Table 2 shows the parameters for 0.75. × The parameters for each lens at different magnification levels are listed. The center thickness refers to the distance along the optical axis between a specified surface of the lens and the next surface. For the front and cemented surfaces of the lens, the center thickness is the lens thickness; for the rear surface, the center thickness is the air gap. Table 3 shows the parameters for 0.75. × 3 × 5 × 6.7 × The air gap adjusted at magnification, 3 × 5 × 6.7 × Other parameters of the lens at magnification are the same as those in Table 2.

[0059] By adjusting the air gaps between the second and fourth lens groups and their preceding and following lens groups, while keeping other air gaps constant, the air gaps between the rear surface of the third meniscus lens 41 and the front surface of the fourth meniscus lens 62, the rear surface of the first biconcave lens 22 and the front surface of the fifth meniscus lens 71, the rear surface of the second biconvex lens 21 and the front surface of the second biconcave lens 32, and the rear surface of the third biconvex lens 42 and the front surface of the fourth biconvex lens 52 change, thus obtaining a value of 0.75. × 3 × 5 × 6.7 × Multiplier. Other 0.75 × -6.7 × The magnification can be adjusted within the aforementioned d1-d4 distance range.

[0060] Table 1: Lens Parameters in Continuous Zoom Lenses

[0061]

[0062] Table 2: 0.75 × Parameter table of each lens at magnification

[0063]

[0064] In Table 2, the first biconvex lens 11 is A1, the first meniscus lens 12 is A2, the second biconvex lens 21 is B1, the first biconcave lens 22 is B2; the second meniscus lens 31 is C1, the second biconcave lens 32 is C2; the third meniscus lens 41 is D1, the third biconvex lens 42 is D2; the third biconcave lens 51 is E1, the fourth biconvex lens 52 is E2; the fifth biconvex lens 61 is F1, the fourth meniscus lens 62 is F2, the fifth meniscus lens 71 is G1, and the sixth meniscus lens 72 is G2.

[0065] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-variation-ratio continuous zoom lens for interference image acquisition, characterized by, Comprise: Along the optical axis direction from object side to image side, in turn set of first lens group, second lens group, third lens group, fourth lens group and fifth lens group.

2. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 1, characterized by, The first lens group comprises from object side to image side in turn set of first double convex lens (11) that first cemented mirror (1) is glued to, first meniscus lens (12), and second double convex lens (21) that second cemented mirror (2) is glued to, first double concave lens (22).

3. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 2, characterized by, The second lens group comprises from object side to image side set of second meniscus lens (31) that third cemented mirror (3) is glued to, second double concave lens (32).

4. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 3, characterized by, The third lens group comprises from object side to image side set of third meniscus lens (41) that fourth cemented mirror (4) is glued to, third double convex lens (42).

5. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 4, characterized by, The fourth lens group comprises from object side to image side set of third double concave lens (51) that fifth cemented mirror (5) is glued to, fourth double convex lens (52).

6. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 5, characterized by, The fifth lens group comprises from object side to image side in turn set of fifth double convex lens (61) that sixth cemented mirror (6) is glued to, fourth meniscus lens (62), and fifth meniscus lens (71) that seventh cemented mirror (7) is glued to, sixth meniscus lens (72).

7. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 6, characterized by, The third cemented mirror (3) and fourth cemented mirror (4) are provided with diaphragm (8) between.

8. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 7, characterized by, The surface of first meniscus lens (12), second meniscus lens (31), fourth meniscus lens (62) towards object side is concave, and the surface of third meniscus lens (41), fifth meniscus lens (71), fifth meniscus lens towards object side is convex.

9. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 8, characterized by, When the second lens group, fourth lens group moves along the optical axis, it is used to adjust the air gap between it and the front and rear lens groups.

10. The high-variation-ratio continuous zoom lens for interference image capturing according to claim 9, characterized by, The air gap between the first lens group and the second lens group is 10.23mm~40.23mm, the air gap between the second lens group and the third lens group is 10.12mm~40.13mm, the air gap between the third lens group and the fourth lens group is 10mm~39.95mm, and the air gap between the fourth lens group and the fifth lens group is 10mm~40mm.

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