Standardized near-infrared laser high-precision scanning and cutting lithography lens

Abstract

The invention discloses a standardized near-infrared laser high-precision scanning cutting lithography objective lens, a first lens with negative optical power, whose object side and image side are both concave; a second lens with negative optical power, whose object side and image side are both concave; a third lens with positive optical power, whose object side is a plane, and whose image side is a convex; a fourth lens with positive optical power, whose object side is a plane, and whose image side is a convex; a fifth lens with positive optical power, whose object side is a convex, and whose image side is a plane; a sixth lens with positive optical power, whose object side is a convex, and whose image side is a plane; a seventh lens with negative optical power, whose object side and image side are both concave; an eighth lens with negative optical power, whose object side is a concave, and whose image side is a plane; a ninth lens with positive optical power, whose object side is a convex, and whose image side is a plane. It has good laser convergence effect, stronger versatility, and better cost performance.

Description

Technical Field

[0001] The invention relates to the technical field of optical objective lenses for medical equipment, and in particular to a standardized near-infrared laser high-precision scanning and cutting lithography objective lens. Background Art

[0002] The standardized near-infrared laser high-precision scanning and cutting lithography objective is mainly used in femtosecond laser myopia correction surgery to converge the laser. In existing use, it is necessary to make the spot of laser convergence as small as possible to reduce the depth of field of the spot, thereby improving the accuracy of laser surgery and reducing the laser power to avoid irreversible protein deterioration of the eyeball due to high-power burning. The existing lenses for infrared light have very good central parallel light beam convergence capabilities, but they will produce serious coma and field curvature for light with a certain tilt angle, and there will be a large error in the application of plane scanning for the light spot, resulting in low power density of the edge light spot or uneven cutting surface; in the existing lens groups for flat field scanning, they have a wide flat field scanning range, and will not have serious aberrations for light with a large tilt angle, but the convergent light spot of this lens group is relatively large, the depth of field is too long, and it cannot be applied to the precise action requirements in ophthalmic surgery; at the same time, the existing optical focusing lenses are basically designed for application scenarios of observing or acting on the surface of objects. In femtosecond laser myopia correction surgery, the laser beam needs to be transmitted through a glass slide and a biological eye cornea of ​​a certain thickness. The existing optical focusing lenses will cause additional aberrations and expansion of the action spot due to the point of action in the cornea, which affects the femtosecond surgery. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a standardized near-infrared laser high-precision scanning and cutting lithography objective lens, which has a simple structure, good laser focusing effect, better overall structural versatility, and better overall cost performance.

[0004] To achieve the above-mentioned purpose, the present invention provides a standardized near-infrared laser high-precision scanning cutting lithography objective lens, comprising a lens body, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens are arranged on the lens body in sequence from the object side to the image side along the optical axis, the first lens, the second lens, the seventh lens and the eighth lens have negative optical focal lengths, the third lens, the fourth lens, the fifth lens, the sixth lens and the ninth lens have positive optical focal lengths, the object side surfaces of the first lens, the second lens, the seventh lens and the eighth lens are concave surfaces, the object side surfaces of the third lens and the fourth lens are plane surfaces, the object side surfaces of the fifth lens, the sixth lens and the ninth lens are convex surfaces, the image side surfaces of the first lens, the second lens and the seventh lens are concave surfaces, the image side surfaces of the third lens and the fourth lens are convex surfaces, and the image side surfaces of the fifth lens, the sixth lens, the eighth lens and the ninth lens are plane surfaces.

[0005] The beneficial effects of this setting are as follows: First, the principle of standardized setting is that the core is to standardize the shape of the lens into several common types, including standard plano-convex lens, plano-concave lens, biconvex lens and biconcave lens. The shape design of these lenses follows certain rules and standards. Specifically, for biconvex and biconcave lenses, their designs adopt a symmetrical structure, which means that the curvature radius values ​​of the two surfaces of these two lenses are equal, which helps to improve the imaging quality and optical performance of the lens. In terms of the constraints on the lens shape, we use the diameter-to-thickness ratio parameter to control it. Specifically, for a convex lens with positive focal length, its diameter-to-thickness ratio needs to reach 5 to 10 times. This ratio can ensure that the lens has a proper focal length while maintaining good mechanical strength and stability. For a concave lens with negative focal length, its diameter-to-thickness ratio needs to reach 10 to 20 times. This design helps to optimize the optical performance of the lens and make it play a better role in the imaging process. In addition, the numerical design of the standard focal length also follows certain rules, that is, it is set in multiples of 25mm. Such a design is convenient for standardized management during the production process and can meet the focal length requirements of different application scenarios. Through such a setting, the overall processing efficiency of the lens is improved and the performance of the single lens after processing is standardized. The effectiveness and standardization of the overall lithography objective are guaranteed, while the replaceability is reserved in the event of damage to a single lens. By using the first lens, the second lens diffuses the light within a certain range; the third lens and the fourth lens are used to re-collimate the light beam respectively to achieve the effect of laser beam expansion. The beam expansion effect can be expressed as a 2.5-fold magnification of 20mm to 50mm; the fifth lens plays an overall convergence role, and the seventh and eighth lenses, through their own negative optical focal length, produce a large amount of reverse spherical aberration, which offsets and neutralizes the positive spherical aberration produced by the sixth and ninth lenses before and after; the ninth lens produces focusing and neutralization of spherical aberration operations to further converge the light. The reintegrated light is focused paraxially, so that the optical lens can make the laser energy at the center of the spot reach 80% of the overall laser injection energy, which can achieve full application of laser energy, improve the precision of cutting operations, and solve the problem of low energy density in the prior art. Preferably, the objective lens body is used for a femtosecond laser with a wavelength of 1030nm, and the scanning range of the lens body is set to a circular range with a diameter of 9mm~10mm, ensuring that the action spot of the lens body is accurate to 3 microns as a resolution unit, ensuring the operational reliability and accuracy of the structure, and having a good use effect.

[0006] As a further configuration of the present invention, the effective focal length of the lens body is 31.02 mm, the entrance pupil diameter of the lens body is 20 mm, and the ratio F number of the focal length of the lens body to the entrance pupil diameter is 1.55.

[0007] The beneficial effects of such a setting are: reasonable structural arrangement, ensuring the use effect of the lens, ensuring the focusing effect of laser energy, improving the use reliability of the structure in theoretically high-precision application scenarios, and having good use effects.

[0008] As a further configuration of the present invention, the total optical length of the mirror body is 288 mm.

[0009] The beneficial effect of such a setting is that the overall structure is more compact. As a preferred embodiment, the back focal distance of the lens is controlled at 30 mm, which can fully reserve a reasonable spacing for each lens to be installed in the overall mirror body, avoid interference of the mirror body during installation, and reserve enough volume space for installation and replacement of disposable biological interfaces in practical applications. It ensures the use effect, the stability of the function, and has a good use effect.

[0010] As a further configuration of the present invention, the effective scanning angle of the mirror body is 4.5° in all directions.

[0011] The beneficial effects of such a setting are: ensuring the focusing effect of the structure, ensuring the illumination intensity and uniformity at the illumination position, making the scanning range a circular range with a diameter of 9mm~10mm, and ensuring the use effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 A schematic diagram of the structure of an optical lens provided by an embodiment of the present invention;

[0013] Figure 2 A schematic diagram of incident light at a high field of view tilt angle of an optical lens provided by an embodiment of the present invention;

[0014] Figure 3 A schematic diagram of parallel incident light rays with zero field of view of an optical lens provided by an embodiment of the present invention;

[0015] Figure 4 A No. 1 field of view point diagram of the optical lens provided by an embodiment of the present invention;

[0016] Figure 5 A second field of view point diagram of the optical lens provided by an embodiment of the present invention;

[0017] Figure 6 A third field of view point diagram of the optical lens provided by an embodiment of the present invention;

[0018] Figure 7 An optical path difference curve diagram No. 1 of the optical lens provided by an embodiment of the present invention;

[0019] Figure 8 A second optical path difference curve diagram of the optical lens provided by an embodiment of the present invention;

[0020] Fig. 9 A third optical path difference curve diagram of the optical lens provided by an embodiment of the present invention;

[0021] Fig.10 A circled energy fraction curve diagram of the optical lens provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention provides a first embodiment of a standardized near-infrared laser high-precision scanning and cutting lithography objective lens. Figures 1 to 3 As shown, it comprises a lens body, on which a first lens E1 with negative optical power is arranged in sequence from the object side to the image side along the optical axis, and its object side surface S1 and its image side surface S2 are both concave surfaces; a second lens E2 with negative optical power, its object side surface S3 and its image side surface S4 are both concave surfaces; a third lens E3 with positive optical power, its object side surface S5 is a plane surface, and its image side surface S6 is a convex surface; a fourth lens E4 with positive optical power, its object side surface S7 is a plane surface, and its image side surface S8 is a convex surface; a fifth lens E4 with positive optical power The object-side surface S9 of the lens E5 is convex, and the image-side surface S10 is a plane. The sixth lens E6 with positive refractive power has a convex object-side surface S11 and a flat image-side surface S12. The seventh lens E7 with negative refractive power has concave object-side surface S13 and image-side surface S14. The eighth lens E8 with negative refractive power has a concave object-side surface S15 and a flat image-side surface S16. The ninth lens E9 with positive refractive power has a convex object-side surface E17 and a flat image-side surface S18.

[0023] Each lens in this embodiment strictly follows the standardized design principle, and its shape is standardized into four basic types: standard plano-convex lens, plano-concave lens, biconvex lens and biconcave lens. These lenses not only have their own standard focal lengths, but also their sizes meet specific standards. The value of the standard focal length is carefully designed to be a multiple of 25mm. This design not only simplifies the standardized management in the production process, but also can meet the specific requirements of various application scenarios for focal length. In terms of the size of the lens, the lens diameter in this embodiment is controlled to be a multiple of 1 inch or a multiple of 25mm. Such a design not only ensures the interchangeability of the lens, but also facilitates batch manufacturing in the production process. For concave lenses, the ratio of their diameter to center thickness is strictly controlled between ten and twenty times, while for convex lenses, this ratio is controlled between five and ten times. Such a diameter-to-thickness ratio design helps to optimize the optical performance of the lens while ensuring its mechanical strength and stability during use. In the design of biconvex and biconcave lenses, this embodiment adopts a symmetrical structure, that is, the values ​​of the curvature radius of the two surfaces of these two lenses are equivalent. This symmetrical design not only helps to improve the imaging quality of the lens, but also makes the lens processing process easier. In addition, this design is also convenient for standardized performance evaluation of the processed single lens, thereby ensuring that each lens can achieve the expected optical performance. Through this standardized component setting principle, this embodiment can achieve efficient production and quality control of the lens. This not only ensures the effectiveness and standardization of the overall lithography objective, but also provides replaceability in the event that a single lens is damaged, thereby improving the reliability and stability of the optical system.

[0024] The nine lenses in this embodiment adopt a design strategy in which convex lenses and concave lenses each account for half. This design can effectively use the concave lens to offset the wavefront difference generated when the light beam passes through the convex lens, thereby improving the optical performance of the entire lithography objective. By cleverly combining the concave lens and the convex lens, this embodiment can achieve more precise beam control, so that the lithography objective can show excellent performance in various application scenarios. In the structural design of the lithography objective, starting from the fifth lens, this embodiment adopts a design that is symmetrical with the front lens. This symmetrical structure can effectively reduce the effects of coma and field curvature caused by high field angles. In the application scenario of high field angles, coma and field curvature often seriously affect the imaging quality, and the symmetrical structural design of this embodiment can effectively reduce these effects, thereby improving the clarity and accuracy of imaging. Existing laser surgical equipment, especially those lenses that act on infrared light, often produce serious coma and field curvature for light with a certain tilt angle. These coma and field curvature will cause the light spot to produce a significant diffusion state under the action of tilted incident light, thereby affecting the accuracy and safety of the operation. However, the photolithography objective lens design of this embodiment can effectively reduce the influence of these coma aberrations and field curvature, so that the light spot remains in a smaller diffuse state under the action of oblique incident light, thereby improving the accuracy and safety of laser surgery. In summary, the nine-lens design of this embodiment adopts a strategy of half convex lens and half concave lens, as well as a symmetrical structural design starting from the fifth lens, which can effectively reduce the influence of coma aberration and field curvature and improve the optical performance of the photolithography objective lens. This not only provides a more accurate and safe solution for laser surgery equipment, but also provides strong support for other application scenarios that require high-precision optical systems.

[0025] The focused light spot produced by the optical lens provided in this embodiment is close to the theoretical diffraction limit range, and the spot diameter is 3um. Not only can the light spot be scanned within a circular range with a diameter of 10mm, and the light spot does not produce obvious dispersion due to the oblique incident light, but the laser energy at the center of the light spot can reach 80% of the overall laser incident energy, which can achieve full application of laser energy, improve the precision of lithography operations, solve the problem of low energy density in the prior art, and also solve the problem of obvious dispersion caused by oblique incident light in the prior art.

[0026] The window mirror in this embodiment is specifically a biological interface protection window mirror of the optical lens, and its thickness is preferably 1 mm. The aperture ST in this embodiment is specifically an aperture aperture, which is used to control the size of the light entry range of the entire optical lens.

[0027] The lenses in the optical lens provided in this example are all made of N-BK7 borosilicate crown glass. The relevant parameters of each lens in the optical lens provided in this example are shown in Table 1:

[0028]

[0029] Table 1

[0030] The present invention provides a second embodiment of a standardized near-infrared laser high-precision scanning cutting lithography objective lens. Based on the embodiment, the effective focal length of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens is 31.02 mm, the system F number of the optical lens is 1.55, the entrance pupil diameter is 20 mm, the total optical length is 288 mm, and the effective scanning angle is 4.5 degrees in all directions. As a preferred lens body, it is used for a femtosecond laser with a wavelength of 1030 nm, and the scanning range is a circular range with a diameter of 9 mm.

[0031] In this embodiment, the action point simulation MS is a surface simulation of the cornea of ​​the eyeball by the photolithography objective lens, indicating effective focusing at 0.1 mm below the cornea of ​​the eyeball. The refractive index of the simulated cornea is about 1.376, and the Abel number is 55.

[0032] In the existing lens groups for flat field scanning, they have a wide flat field scanning range, and will not have serious aberration for light with large tilt angles, but the convergent spot of this lens group is relatively large, the depth of field is too long, and the precision action requirements in ophthalmic surgery are high, so the existing flat field scanning lens group cannot be directly applied to ophthalmic surgery. The optical lens provided in this embodiment is used for the convergence effect and function of the laser in femtosecond laser myopia correction surgery. For the converged spot of the laser, the action point is required to be as small as possible, and the depth of field range of the spot is reduced to improve the accuracy of laser surgery and reduce the use of laser power.

[0033] like Figure 4-Figure 6 , the No. 1 field of view spot diagram, the No. 2 field of view spot diagram, and the No. 3 field of view spot diagram are all obtained based on a zoom bar of 6um and a reference to the center of mass. The data in the figure reflects that the diffraction limit size of the spot is 1.949 microns. When the light beam is not incident at an inclined angle, its image plane height is also centered. The effective energy spot radius size is 1.153um, and the geometric radius size is 2.995um. Each figure shows their image plane height and the effective energy spot radius size and geometric radius size of each point when incident at different inclined angles. The maximum inclination angle is 4.5 degrees, the image plane height is 4.41mm, the effective energy spot radius size is 1.050um, and the geometric radius size is 2.995um. Table 2 shows the RMS radius and GEO radius parameters of the No. 1 field of view spot diagram, the No. 2 field of view spot diagram, and the No. 3 field of view spot diagram:

[0034] Field of view On-axis field of view 0.707x field of view Maximum field of view RMS radius (um) 1.153 0.620 1.050 GEO radius (um) 2.995 1.635 2.029

[0035] Table 2

[0036] Reference Figure 7-Figure 9 From the data in the figure, we can see that the wavefront difference of each field of view does not exceed the range of 0.5 times the wavelength, that is, the wavefront difference exceeding one wavelength will produce mutually canceling interference effects and affect the experiment. In detail, the wavefront aberration is less than 0.5 times the wavelength, which can improve the uniformity of the laser beam energy and reduce the interference effect within the laser. It should be noted that Figure 7-Figure 9 The optical path difference curves shown are all completed under the parameter of the maximum scaling ratio of plus or minus 0.5 waves.

[0037] Further Fig.10 As shown, the parameters of the field curvature curve are that the maximum field of view is 4.5000 degrees, and the legend corresponds to the wavelength. The data in the figure show that the optical lens provided in this embodiment has a sagittal field curvature of 0.0066 mm and a meridional field curvature of 0.0067 mm. The final field curvature is 0.0066 mm, that is, the focal plane of the maximum field angle differs from the focal plane of the center by only 6 microns.

[0038] The above example is only one preferred specific example of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention are all included in the protection scope of the present invention.

Claims

1. A standardized near-infrared laser high-precision scanning and cutting lithography objective lens, characterized in that: The invention comprises a lens body, wherein a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a ninth lens are sequentially arranged on the lens body along an optical axis from an object side to an image side, wherein the first lens, the second lens, the seventh lens and the eighth lens have negative optical focal lengths, and the third lens, the fourth lens, the fifth lens, the sixth lens and the ninth lens have positive optical focal lengths, the object side surfaces of the first lens, the second lens, the seventh lens and the eighth lens are concave surfaces, the object side surfaces of the third lens and the fourth lens are plane surfaces, the object side surfaces of the fifth lens, the sixth lens and the ninth lens are convex surfaces, the image side surfaces of the first lens, the second lens and the seventh lens are concave surfaces, the image side surfaces of the third lens and the fourth lens are convex surfaces, and the image side surfaces of the fifth lens, the sixth lens, the eighth lens and the ninth lens are plane surfaces.

2. The standardized near-infrared laser high-precision scanning and cutting lithography objective lens according to claim 1 is characterized in that: The effective focal length of the lens body is 31.02 mm, the entrance pupil diameter of the lens body is 20 mm, and the ratio F number of the focal length of the lens body to the entrance pupil diameter is 1.

55.

3. The standardized near-infrared laser high-precision scanning and cutting lithography objective lens according to claim 1 is characterized in that: The total optical length of the mirror body is 288 mm.

4. The standardized near-infrared laser high-precision scanning and cutting lithography objective lens according to claim 1 is characterized in that: The effective scanning angle of the mirror is 4.5° in all directions.

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