A continuous zoom laser illumination optical system

Abstract

The invention relates to the field of laser lighting technology, and in particular to a continuous zoom laser lighting optical system, comprising a coaxially arranged front fixed lens group, a variable magnification lens group, a compensating lens group, an aperture, and a rear fixed lens group; the leftmost side is an object plane, and the rightmost side is a light source plane; the front fixed lens group comprises a first positive lens and a second positive lens arranged in sequence from left to right along an optical axis; the variable magnification lens group comprises a first negative lens; the compensating lens group comprises a third positive lens and a fourth positive lens arranged in sequence from left to right along the optical axis; the rear fixed lens group comprises a second negative lens and a fifth positive lens arranged in sequence from left to right along the optical axis; the aperture is fixedly arranged on the left side of the second negative lens; the variable magnification lens group and the compensating lens group move synchronously along the left and right directions of the optical axis to realize continuous zooming; passive adaptation in a wide temperature range can be realized, and a continuous zooming function of not less than 200 times can be realized; in the process of continuous change of focal length, all focal lengths have good illumination uniformity in the full field of view.

Description

Technical Field

[0001] The invention belongs to the technical field of laser lighting, and in particular relates to a continuous zoom laser lighting optical system. Background Art

[0002] Laser active illumination technology is mainly used to supplement the illumination of target scenes with poor lighting conditions and assist imaging equipment in completing image information collection. With the development of modern optoelectronic technology, the demand for long-distance illumination and identification of targets is increasing in the fields of reconnaissance, mapping, security monitoring, etc., and laser active illumination optical systems are gradually beginning to occupy a major position in related application fields. At the same time, in order to achieve long-distance laser illumination, the optical system must have a certain zoom capability to cover a specific range of illumination angle changes; in order to keep the entire lighting system low-cost, the optical system is required to have a wide operating band range to adapt to laser light sources in different operating bands; in addition, in order to meet the use requirements of the above-mentioned application scenarios, the lighting system is also required to have excellent environmental adaptability. These have put forward urgent demands for the design of wide-band, large-magnification, athermal laser illumination optical systems.

[0003] In particular, for a continuous zoom optical system, during the process of continuous change of focal length, the magnification and aberration characteristics of the imaging system change accordingly due to the change in the relative position of the moving groups, which makes it difficult to design the athermalization at each focal length position of the zoom system. Moreover, the large magnification and large relative aperture of the optical system lead to a larger moving group magnification and a narrower system focal depth range, which also poses a greater challenge to the athermalization design. For some laser illumination zoom optical systems disclosed in existing literature, some of them have a small magnification ratio, a narrow operating band, or fail to achieve the optical passive athermalization function.

[0004] For example: In 2022, a document entitled "Short-wave infrared imaging zoom homogenization laser illumination system" published in the Chinese journal "Journal of Infrared and Millimeter Waves" Volume 37, Issue 3 reported a laser illumination optical system with a zoom range of 2~50° and an operating wavelength of 1.55μm. The optical system consists of three groups of lenses, but adopts a two-moving group external zoom method, that is, the length of the entire optical system changes continuously during the zoom process. If the optical system is to be applied to special fields such as security monitoring, corresponding optical windows need to be added, which further increases the system cost; in addition, the optical structure cannot achieve a wider operating band and a larger magnification ratio, and no athermalization is mentioned.

[0005] Chinese patent CN116699817A discloses a laser illumination optical system composed of three groups of lenses, which also adopts an optical structure of two moving groups with external zoom, with an operating band of 800~1100nm, and achieves an optical zoom of 150x; Chinese patent CN207457618 also discloses a three-group four-piece laser illumination optical system, with an operating band of 808nm, 880nm or 915nm, a zoom range of 0.5~50mm, and achieves an optical zoom of 100x; However, if the optical system in the above patent is to be applied to special fields such as security monitoring, it will have the same problems as in the above literature.

[0006] Chinese patent CN116951359A discloses a laser illumination optical system composed of four groups of lenses, which adopts an optical structure of zooming in two moving groups, with an operating wavelength of 808nm and a magnification of only 6 times; Chinese patent CN 219655927A discloses a laser illumination optical system composed of three groups of lenses, which adopts an optical structure of zooming in two moving groups, with an operating wavelength of 525nm, and a magnification ratio of about 22 times from 4.5 to 100mm; Chinese patent CN 108267849A also discloses a laser illumination optical system composed of three groups of lenses, which adopts an optical structure of zooming in two moving groups, and achieves a magnification ratio of about 80 times from 0.5 to 40mm, and an operating wavelength range of 808 to 980nm; Chinese patent CN The laser lighting system disclosed in 11557688 adopts three groups of lenses and an optical structure with zoom within a single lens group, achieving a zoom range of about 10 times from 0.29 to 2.9°; the optical systems disclosed in these patent documents have limited zoom factors and none of them mention athermalization. Summary of the invention

[0007] In view of this, in order to solve the technical problem that the existing optical system cannot simultaneously achieve a wide operating band, a large zoom ratio and passive compensation for temperature changes, the present invention provides a wide-band, large zoom ratio, athermal continuous zoom laser illumination optical system.

[0008] To achieve the above object, the technical solution created by the present invention is implemented as follows: The present invention provides a continuous zoom laser illumination optical system, which comprises a front fixed lens group, a variable magnification lens group, a compensation lens group, an aperture, and a rear fixed lens group, which are coaxially arranged in sequence from left to right along an optical axis; The left side of the front fixed mirror group includes the object plane of the continuous zoom laser illumination optical system, and the right side of the rear fixed mirror group includes the light source plane of the continuous zoom laser illumination optical system; The front fixed lens group includes a first positive lens and a second positive lens arranged in sequence from left to right along the optical axis; the zoom lens group includes a first negative lens; the compensation lens group includes a third positive lens and a fourth positive lens arranged in sequence from left to right along the optical axis; the rear fixed lens group includes a second negative lens and a fifth positive lens arranged in sequence from left to right along the optical axis; the aperture is fixedly arranged on the left side of the second negative lens; The variable magnification lens group and the compensating lens group move synchronously along the left and right directions of the optical axis to achieve continuous zooming.

[0009] Furthermore, the Abbe number of the first positive lens for the d-line is Vd601, and Vd601>48; the Abbe number of the second positive lens for the d-line is Vd602, and Vd602>56.

[0010] Furthermore, the focal length of the front fixed lens group is f6, the focal length of the telephoto end of the continuous zoom optical system is fL, and fL and f6 satisfy the condition: 1.02<|fL / f6|<1.31.

[0011] Furthermore, the focal length of the zoom lens assembly is f5, and fL and f5 satisfy the conditional expression: 15.1<|fL / f5|<27.4; The Abbe number of the second negative lens for d-line is Vd501, where Vd501<26.

[0012] Furthermore, the focal length of the compensation lens group is f4, and fL and f4 satisfy the conditional formula: 10.2<|fL / f4|<20.3; The Abbe number of the fourth positive lens for d-line is Vd402, where Vd402>60.

[0013] Furthermore, the thermal expansion coefficient of the fifth positive lens is T202, T202≤9.0×10 -6 / K.

[0014] Furthermore, the variable power lens group and the compensating lens group are moved synchronously by a gear-guide mechanism, a cam-sleeve mechanism or a cam-guide mechanism.

[0015] Compared with the prior art, the invention can achieve the following beneficial effects: The laser lighting system provided by the present invention continuously moves according to a given motion law through a zoom core composed of a zoom lens group and a compensation lens group, and the zoom form is internal zoom; during the zooming process, each lens group can be always moved forward and backward on the optical axis, the numerical aperture of the optical system remains constant when the magnification is changed, the total length is fixed, the center of mass changes slightly, the system volume is small, and the structure is simple and compact; passive adaptation to a wide temperature range can be achieved, and uniform illumination can be achieved within the full zoom range, and a continuous zoom function of not less than 200 times can be achieved; in the process of continuous change of focal length, all focal lengths have good illumination uniformity in the full field of view; it has both continuous zoom and wide-band adaptability, can adapt to multi-band lighting light sources, can realize miniaturization, lightness and integration of the lighting system, and can also reduce the difficulty of optical debugging, and can take into account the requirements of the imaging system for large field of view search detection and small field of view recognition for the lighting system.

[0016] In addition, in the continuous zoom laser illumination optical system provided by the present invention, the diaphragm is fixedly arranged on the outer side of the rear fixed lens group close to the object side lens, which can leave enough space for using different types of diaphragms to ensure that the numerical aperture of the continuous zoom optical system remains constant and changes manually or automatically, thereby improving the modularization level of the optical system; on the other hand, the diaphragm is imaged at a long distance on the light source side through the subsequent lens group to form a quasi-image telecentric optical path, which can further ensure the uniformity of illumination; moreover, by adopting a quasi-image telecentric design form and combining the aberration vignetting design method, it is ensured that the optical system has good distortion characteristics under various field of view conditions, and the image plane illumination distribution under various field of view conditions can also be made more uniform; it can be widely used in various application fields such as reconnaissance, mapping, security monitoring, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 A schematic diagram of the optical path of a continuous zoom laser illumination optical system in an embodiment of the present invention; Figure 2 A schematic diagram of the short-focus optical path of the continuous zoom laser illumination optical system in the embodiment of the present invention; Figure 3 A schematic diagram of the optical path of the continuous zoom laser illumination optical system in the mid-focus state in the embodiment of the present invention; Figure 4 A schematic diagram of the optical path of the continuous zoom laser illumination optical system in the telephoto state in the embodiment of the present invention; Figure 5 A schematic diagram of light aberration of a continuous zoom laser illumination optical system in a short-focus state at a temperature of 70° C. in an embodiment of the present invention; Figure 6 A schematic diagram of light aberration of a continuous zoom laser illumination optical system in a short-focus state at a temperature of 20° C. in an embodiment of the present invention; Figure 7 A schematic diagram of light aberration of a continuous zoom laser illumination optical system in a short-focus state at a temperature of -40°C in an embodiment of the present invention; Figure 8 A schematic diagram of light aberration of a continuous zoom laser illumination optical system in a telephoto state at a temperature of 70° C. in an embodiment of the present invention; Fig. 9 A schematic diagram of light aberration of a continuous zoom laser illumination optical system in a telephoto state at a temperature of 20° C. in an embodiment of the present invention; Fig.10 This is a schematic diagram of light aberration of the continuous zoom laser illumination optical system in the telephoto state and at a temperature of -40°C in an embodiment of the present invention.

[0018] Reference numerals: 100-light source surface, 200-rear fixed lens group, 201-second negative lens, 202-fifth positive lens, 300-aperture, 400-compensation lens group, 401-third positive lens, 402-fourth positive lens, 500-magnification lens group, 501-first negative lens, 600-front fixed lens group, 601-first positive lens, 602-second positive lens, 700-object plane. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0020] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0023] In a specific embodiment of the present invention, a continuous zoom laser illumination optical system is provided, wherein the continuous zoom laser illumination optical system comprises a front fixed lens group, a variable magnification lens group, a compensation lens group, an aperture, and a rear fixed lens group which are coaxially arranged in sequence from left to right along the optical axis; The left side of the front fixed mirror group includes the object plane of the continuous zoom laser illumination optical system, and the right side of the rear fixed mirror group includes the light source plane of the continuous zoom laser illumination optical system; The front fixed lens group includes a first positive lens and a second positive lens arranged in sequence from left to right along the optical axis; the zoom lens group includes a first negative lens; the compensation lens group includes a third positive lens and a fourth positive lens arranged in sequence from left to right along the optical axis; the rear fixed lens group includes a second negative lens and a fifth positive lens arranged in sequence from left to right along the optical axis; the aperture is fixedly arranged on the left side of the second negative lens; The front fixed lens group, the magnification lens group, the compensating lens group, the diaphragm, and the rear fixed lens group constitute a complete continuous zoom laser illumination optical system; the magnification lens group and the compensating lens group constitute a continuous zoom optical system; the magnification lens group and the compensating lens group move synchronously along the left and right directions of the optical axis to achieve continuous zoom.

[0024] In a specific implementation manner, the Abbe number of the first positive lens for the d-line is Vd601, Vd601>48; the Abbe number of the second positive lens for the d-line is Vd602, Vd602>56. The focal length of the front fixed lens group is f6, the focal length of the telephoto end of the continuous zoom optical system is fL, and fL and f6 satisfy the condition: 1.02<|fL / f6|<1.31. The focal length of the variable magnification lens group is f5, and fL and f5 satisfy the condition: 15.1<|fL / f5|<27.4; the Abbe number of the second negative lens for the d-line is Vd501, Vd501<26. The focal length of the compensation lens group is f4, and fL and f4 satisfy the condition: 10.2<|fL / f4|<20.3; the Abbe number of the fourth positive lens for the d-line is Vd402, Vd402>60. The thermal expansion coefficient of the fifth positive lens is T202, T202≤9.0×10 -6 / K; the surface close to the object plane is defined as the front surface, and the surface close to the light source plane is defined as the rear surface; the zoom lens group and the compensation lens group are synchronously moved along the left and right directions of the optical axis through a gear-guide mechanism, a cam-sleeve mechanism or a cam-guide mechanism to achieve continuous zooming.

[0025] The laser lighting system provided by the present invention continuously moves according to a given motion law through a zoom core composed of a zoom lens group and a compensation lens group, and the zoom form is internal zoom; during the zooming process, each lens group can be always moved forward and backward on the optical axis, the numerical aperture of the optical system remains constant when the magnification is changed, the total length is fixed, the center of mass changes slightly, the system volume is small, and the structure is simple and compact; passive adaptation to a wide temperature range can be achieved, and uniform illumination can be achieved within the full zoom range, and a continuous zoom function of not less than 200 times can be achieved; in the process of continuous change of focal length, all focal lengths have good illumination uniformity in the full field of view; it has both continuous zoom and wide-band adaptability, can adapt to multi-band lighting light sources, can realize miniaturization, lightness and integration of the lighting system, and can also reduce the difficulty of optical debugging, and can take into account the requirements of the imaging system for large field of view search detection and small field of view recognition for the lighting system.

[0026] In addition, in the continuous zoom laser illumination optical system provided by the present invention, the diaphragm is fixedly arranged on the outer side of the rear fixed lens group close to the object side lens, which can leave enough space for using different types of diaphragms to ensure that the numerical aperture of the continuous zoom optical system remains constant and changes manually or automatically, thereby improving the modularization level of the optical system; on the other hand, the diaphragm is imaged at a long distance on the light source side through the subsequent lens group to form a quasi-image telecentric optical path, which can further ensure the uniformity of illumination; moreover, by adopting a quasi-image telecentric design form and combining the aberration vignetting design method, it is ensured that the optical system has good distortion characteristics under various field of view conditions, and the image plane illumination distribution under various field of view conditions can also be made more uniform; it can be widely used in various application fields such as reconnaissance, mapping, security monitoring, etc.

[0027] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0028] like Figure 1 As shown in the figure, it is a schematic diagram of the optical path of a wide-band, large-zoom-ratio athermal continuous-zoom laser illumination optical system provided by a specific embodiment of the present invention. It can be seen from the figure that the continuous-zoom laser illumination optical system of this embodiment includes a front fixed lens group 600, a zoom lens group 500, a compensating lens group 400, an aperture 300 and a rear fixed lens group 200 coaxially arranged in sequence from left to right along the optical axis. The left side of the front fixed lens group 600 is the object plane 700 of the continuous-zoom laser illumination optical system, and the right side of the rear fixed lens group is the light source plane 100 of the continuous-zoom laser illumination optical system; the zoom lens group 500, the front fixed lens group 600, the compensating lens group 400, the aperture 300 and the rear fixed lens group 200 together constitute a complete continuous-zoom laser illumination optical system. The zoom lens group 500 and the compensating lens group 400 are synchronously moved linearly in the left and right directions of the optical axis of the optical system through a driving mechanism to achieve continuous zooming; specifically, the driving mechanism can be a gear-guide mechanism, a cam-sleeve mechanism or a cam-guide mechanism or other similar driving mechanisms. In the present invention, the total length of the system remains unchanged during the change of focal length.

[0029] Specifically, in this embodiment, the front fixed lens group 600 includes a first positive lens 601 and a second positive lens 602 coaxially arranged from left to right along the central axis; in this way, a front fixed lens group 600 having a longer focal length and positive optical focal length, i.e., positive refractive power, can be configured on the side of the continuous zoom laser illumination optical system closest to the object plane 700, which is conducive to the miniaturization of the entire continuous zoom laser illumination optical system.

[0030] The Abbe number of the first positive lens 601 for the d-line is Vd601, and the Abbe number of the second positive lens 602 for the d-line is Vd602. Vd601 and Vd602 satisfy the following conditional formula: Vd601>48; (1) Vd602>56; (2) Conditional expressions (1) and (2) are conditional expressions that stipulate that the chromatic aberration generated by the front fixed lens group 600 across the full zoom range relative to the entire working spectrum range is well corrected. By forming the first positive lens 601 in the front fixed lens group 600 with a material that satisfies conditional expression (1) and forming the second positive lens 602 in the front fixed lens group 600 with a low dispersion material that satisfies conditional expression (2), the chromatic aberration generated across the full zoom range relative to the entire working spectrum range can be well corrected in the full zoom range. In addition, if the range of conditional expression (1) is exceeded or the lower limit of conditional expression (2) is lowered, it becomes difficult to correct the chromatic aberration introduced by the working medium; therefore, the use of conditional expressions (1) and (2) is the optimal solution.

[0031] The focal length of the front fixed lens group 600 is f6, and the focal length of the long focal end of the wide-band large zoom ratio athermal continuous zoom laser illumination optical system is fL. fL and f6 satisfy the following conditional formula: 1.02<|fL / f6|<1.31; (3) Conditional formula (3) is a formula that specifies that the effect of the front fixed lens group 600 on the defocus at the telephoto end of the optical system is minimized; by limiting the focal length of the front fixed lens group 600 to satisfy conditional formula (3), the defocus caused by the change in ambient temperature in the full zoom range, especially in the telephoto range, can be well corrected. In addition, if the range of conditional formula (3) is exceeded, it becomes difficult to correct the temperature defocus of the optical system in the telephoto range; therefore, conditional formula (3) is the optimal solution.

[0032] Specifically, in this embodiment, the zoom lens group 500 is a single-lens structure, composed of a first negative lens 501; the zoom lens group 500 can compress the aperture of the rear group, and well correct the aberrations associated with the large aperture, ensuring that the optical system can zoom quickly, and can better correct the chromatic aberration generated by light in the entire working spectrum range across the full zoom area.

[0033] The focal length of the zoom lens group 500 is f5, the Abbe number of the first negative lens 501 for the d-line is Vd501, and fL, f5 and Vd501 satisfy the following conditional formula: 15.1<|fL / f5|<27.4; (4) Vd501<26; (5) Conditional expression (4) is an expression for limiting the focal length range of the zoom lens group 500. By satisfying conditional expression (4), it is possible to ensure that the optical system can zoom quickly and to achieve miniaturization of the optical system. In conditional expression (4), if the lower limit is lower than the lower limit, the movement amount of the zoom lens group 500 increases, so miniaturization of the optical system becomes difficult. On the other hand, if the upper limit of conditional expression (4) is exceeded, it is beneficial to miniaturization of the optical system, but it becomes difficult to correct coma and astigmatism at the short focal end, and optical performance deteriorates, which becomes a problem. Therefore, adopting conditional expression (4) is the best solution.

[0034] Conditional expression (5) is a conditional expression that stipulates that the chromatic aberration generated by the zoom lens group 500 relative to the light in the entire working spectrum range can be well corrected across the full zoom range; by forming the first negative lens 501 in the zoom lens group 500 with a high dispersion material that satisfies conditional expression (5), the chromatic aberration generated relative to the light in the working spectrum range can be well corrected in the full zoom range. In addition, in conditional expression (5), if it is lower than its lower limit, it becomes difficult to correct the axial chromatic aberration, and it is impossible to fully correct the chromatic aberration generated by the light in the entire working spectrum range; therefore, adopting conditional expression (5) is the optimal solution.

[0035] In this way, the zoom lens assembly 500 can effectively compress the incident angle of light on the surface of the rear lens group, thereby reducing the difficulty of aberration correction of the rear lens group.

[0036] Specifically, in this embodiment, the compensating lens group 400 is a double-separated structure, including a third positive lens 401 and a fourth positive lens 402 arranged from left to right; the focal length of the compensating lens group 400 is f4, the Abbe number of the fourth positive lens 402 for the d-line is Vd402, and fL, f4 and Vd402 satisfy the following conditional formula: 10.2<|fL / f4|<20.3; (6) Vd402>60. (7) Conditional expression (6) is an expression for limiting the focal length range of the compensation lens group 400 accompanying the zoom lens group; by satisfying conditional expression (6), it is possible to ensure that the compensation lens group 400 of the optical system moves smoothly and quickly, and can better correct the field curvature at the telephoto end. If conditional expression (6) is below its lower limit, the movement amount of the compensation lens group 400 increases, and miniaturization of the optical system becomes difficult; on the other hand, if conditional expression (6) is above its upper limit, correction of field curvature at the telephoto end becomes difficult, and optical performance deteriorates, which becomes a problem.

[0037] The conditional expression (7), like the conditional expressions (1), (2) and (5), is a conditional expression for correcting the chromatic aberration generated by the light in the entire working spectrum range across the full zoom range. The fourth positive lens 402 of the compensation lens group 400 is formed by using a low dispersion material that satisfies the conditional expression (7), and the chromatic aberration generated by the light in the entire working spectrum range across the full zoom range is further corrected well; in addition, if the conditional expression (7) exceeds its upper limit, it becomes difficult to correct the off-axis chromatic aberration in the compensation lens group 400; therefore, the conditional expression (7) is the best solution.

[0038] In this way, the compensating lens group 400 can independently correct the chromatic aberration produced by each lens in the group, and partially compensate for the field curvature and distortion introduced by the zoom lens group 500.

[0039] Specifically, in this embodiment, the rear fixed lens group 200 includes a second negative lens 201 and a fifth positive lens 202 arranged from left to right; the thermal expansion coefficient of the fifth positive lens is T202, and T202 satisfies the following conditional formula: T202 ≤ 9.0×10 -6 / K(8) Conditional expression (8) is a formula for correcting the thermal difference associated with the short focal end of the optical system. By satisfying conditional expression (8), the defocus amount of the entire optical system in the short focal length can be maintained, and the environmental adaptability of the optical system in the short focal length under different usage conditions can be guaranteed. If conditional expression (8) is higher than its upper limit, the thermal expansion coefficient of the fifth positive lens 202 becomes larger, and the defocus amount in the short focal length environment becomes larger, so that the heat removal of the optical system becomes difficult and becomes a problem. Therefore, adopting conditional expression (8) is the optimal solution.

[0040] As described above, the continuous zoom laser illumination optical system of this embodiment can achieve wide-band, athermal, and continuous zoom by simultaneously satisfying or satisfying multiple of the above conditions, and can well correct the aberrations generated by light in the entire working spectrum range in the full magnification region, thereby obtaining better optical performance.

[0041] like Figures 2 to 4 As shown, the zoom lens group 500 and the compensation lens group 400 move linearly forward and backward in a certain pattern from left to right in the direction of the optical axis of the continuous zoom laser illumination optical system of this embodiment, that is, Figure 1 When changing from a wide field of view to a narrow field of view, the zoom lens group 500 is translated toward the side close to the light source surface 100, and the compensation lens group 400 is adaptively moved, such as Figure 4 The telephoto state is shown; when changing from a narrow field of view to a wide field of view, the zoom lens group 500 moves toward one side of the object plane 700, and the compensation lens group moves adaptively, such as Figure 2The figure shows the short focus state; the focal length changes continuously during the movement, and the light path in the medium focus state is as follows Figure 3 shown.

[0042] The continuous zoom laser illumination optical system of this embodiment has four lens groups, which are sequentially arranged from the object plane 700 to the light source plane 100, namely, a front fixed lens group 600 with positive focal length, i.e., a refractive power, a variable magnification lens group 500 with negative focal length, a compensating lens group 400 with positive focal length, an aperture 300, and a rear fixed lens group 200 with positive focal length, and a light emitting surface such as an optical fiber light source is arranged on the light source plane 100. Various numerical data related to the zoom optical system involved in the embodiment are as follows: Illumination field of view: (2ω) = 1mrad (telephoto end) ~ 200mrad (short focal end) Numerical aperture NA: 0.22 Working band range: 650nm~950nm Athermal temperature range: -40℃~+70℃ The following Tables 1, 2 and 3 respectively represent various optical parameter data in the continuous zoom laser illumination optical system of this embodiment.

[0043] Table 1 Specific parameters of each lens of the continuous zoom laser illumination optical system of this embodiment (Unit: mm)

[0044] Table 2 Variable surface spacing data of the continuous zoom laser illumination optical system of this embodiment (Unit: mm)

[0045] Table 3 Parameters of the continuous zoom laser illumination optical system of this embodiment

[0046] The total number of lenses of the continuous zoom laser illumination optical system of this embodiment is small and has good tolerance characteristics; the optical materials used in each lens group are all common optical glass materials, and have good availability and processability.

[0047] The continuous zoom laser illumination optical system of the embodiment of the present invention adopts a lens material combination that matches the linear expansion coefficient of the lens barrel material and an optical passive athermalization method in the full temperature range of -40°C to +70°C to compensate for the defocus caused by the temperature change of the lens barrel material. Figures 5 to 7As shown in FIG. 1 , it is a schematic diagram of light aberration of the continuous zoom laser illumination optical system in the embodiment of the present invention at three different temperatures of 70° C., 20° C. and -40° C. in the short-focus state. It can be seen from the figure that the continuous zoom laser illumination optical system of the embodiment completes good correction of aberrations such as spherical aberration, coma, and astigmatism in the short-focus state; Figures 8 to 10 As shown, it is a schematic diagram of light aberrations of the continuous zoom laser illumination optical system in the embodiment of the present invention at three different temperatures of 70°C, 20°C and -40°C in the telephoto state. It can be seen from the figure that the continuous zoom laser illumination optical system of the embodiment achieves good correction of aberrations such as spherical aberration, coma, astigmatism, etc. in the telephoto state.

[0048] The lens barrel installed in the continuous zoom laser illumination optical system of the embodiment of the present invention is made of ordinary aluminum alloy material, and its thermal expansion coefficient is 23.6×10 -6 / K, no other barrel material with a lower thermal expansion coefficient is required. In this embodiment, the total length from the surface of the front fixed lens group 600 close to the object plane 700 to the light source surface 100 is no more than 215mm, the maximum diameter of each lens is no more than 100mm, the focal length range is 1mm to 200mm, the zoom ratio is 200, and it is suitable for light sources with a light-emitting surface diameter of 200μm. During the zoom process, the total length of the system is constant, the numerical aperture NA is fixed and unchanged, and it changes continuously with the change of the focal length position. It has a small volume and light weight, and it belongs to internal zoom, and the center of mass does not change much during the zoom process.

[0049] In the present embodiment, the diaphragm 300 of the continuous zoom laser illumination optical system is fixedly located on the outer side of the rear fixed lens group 200 close to the object side lens, which can leave enough space for using different types of diaphragms to ensure that the numerical aperture of the continuous zoom optical system remains constant and can be changed manually or automatically, thereby improving the modularization level of the optical system; on the other hand, the diaphragm is imaged at a long distance on the light source side through the subsequent lens group to form a quasi-image-side telecentric optical path, which can further ensure the uniformity of illumination.

[0050] It can be seen from the above data that by adopting the laser illumination optical structure of the present invention, a zoom ratio of not less than 200 times can be achieved using only seven lenses, which effectively improves the zoom capability of the existing illumination optical system.

[0051] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0052] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A continuous zoom laser illumination optical system, characterized in that: The continuous zoom laser illumination optical system comprises a front fixed lens group, a variable magnification lens group, a compensation lens group, an aperture, and a rear fixed lens group which are coaxially arranged in sequence from left to right along the optical axis; The left side of the front fixed mirror group includes the object plane of the continuous zoom laser illumination optical system, and the right side of the rear fixed mirror group includes the light source plane of the continuous zoom laser illumination optical system; The front fixed lens group includes a first positive lens and a second positive lens arranged in sequence from left to right along the optical axis; the zoom lens group includes a first negative lens; the compensation lens group includes a third positive lens and a fourth positive lens arranged in sequence from left to right along the optical axis; the rear fixed lens group includes a second negative lens and a fifth positive lens arranged in sequence from left to right along the optical axis; the aperture is fixedly arranged on the left side of the second negative lens; The variable magnification lens group and the compensating lens group move synchronously along the left and right directions of the optical axis to achieve continuous zooming.

2. The continuous zoom laser illumination optical system according to claim 1, characterized in that: The Abbe number of the first positive lens for the d-line is Vd601, where Vd601>48; the Abbe number of the second positive lens for the d-line is Vd602, where Vd602>56.

3. The continuous zoom laser illumination optical system according to claim 1, characterized in that: The focal length of the front fixed lens group is f6, the focal length of the telephoto end of the continuous zoom laser illumination optical system is fL, and fL and f6 satisfy the condition: 1.02<|fL / f6|<1.

31.

4. The continuous zoom laser illumination optical system according to claim 1, characterized in that: The focal length of the zoom lens group is f5, the focal length of the telephoto end of the continuous zoom laser illumination optical system is fL, and fL and f5 satisfy the condition: 15.1<|fL / f5|<27.4; The Abbe number of the second negative lens for d-line is Vd501, where Vd501<26.

5. The continuous zoom laser illumination optical system according to claim 1, characterized in that: The focal length of the compensation lens group is f4, the focal length of the telephoto end of the continuous zoom laser illumination optical system is fL, and fL and f4 satisfy the condition: 10.2<|fL / f4|< 20.3; The Abbe number of the fourth positive lens for d-line is Vd402, where Vd402>60.

6. The continuous zoom laser illumination optical system according to claim 1, characterized in that: The thermal expansion coefficient of the fifth positive lens is T202, T202 ≤ 9.0×10 -6 / K.

7. The continuous zoom laser illumination optical system according to claim 1, characterized in that: The variable power lens group and the compensating lens group are moved synchronously by a gear-guide mechanism, a cam-sleeve mechanism or a cam-guide mechanism.

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