A 3D printing lens and a 3D printing device

Abstract

Embodiments of the present application provide a 3D printing lens and a 3D printing device; the 3D printing lens comprises, in order from an object side to an image side along an optical axis, a first lens group, a second lens group, a diaphragm, a third lens group and an imaging chip group; wherein the first lens group comprises ≤2 independent glass spherical lenses, and the overall optical power φ1<0; the second lens group comprises ≤3 independent glass spherical lenses, and the overall optical power φ2>0; the third lens group comprises ≤5 independent glass spherical lenses, and the overall optical power φ3>0; the imaging chip group comprises a galvanometer, a light splitting prism and an imaging chip; wherein all the lenses satisfy: a thermal expansion coefficient TCE≤12.7×10 ‑6 / K; a refractive index 1.48≤Nd≤1.81; an Abbe number 33.2≤Vd≤81.7; the second lens group comprises independently movable lenses, and the back focal length between the third lens group and the imaging chip is adjustable.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of optical imaging technology, and more particularly, to a 3D printing lens and a 3D printing device. BACKGROUND

[0002] 3D printing technology, also known as additive manufacturing technology, is a new manufacturing technology that builds materials layer by layer based on digital models to manufacture physical objects. In recent years, with the continuous progress of technology, 3D printing devices have been widely used in dentistry, small part batch production, mold manufacturing and other fields, especially in small size and small batch demand scenarios. At present, 3D printing devices based on digital light processing (DLP) technology are particularly popular, and the printed parts have the characteristics of high precision and fast printing.

[0003] In the 3D printing device, the 3D printing lens as one of the key components directly affects the precision and quality of the printed part. However, with the continuous improvement of the integration of 3D printing devices, 3D printing is often placed in a closed space, resulting in large temperature changes in the working environment. This temperature change will cause thermal expansion or contraction of the lens material, and then cause the drift of the ideal focal plane of the lens, which is called the "temperature drift" phenomenon. Temperature drift will cause the resolution of the lens to decrease, the printing precision to decrease, and seriously affect the overall performance of the 3D printing device.

[0004] At present, although there are some technologies for improving the temperature drift problem of 3D printing lenses, these technologies often have high cost, limited effect or difficulty in balancing resolution and cost. Therefore, it is an urgent need in the current technical field to develop a 3D printing lens that can effectively suppress the temperature drift effect while ensuring high resolution and reasonable cost. SUMMARY

[0005] The purpose of the present application is to provide a new technical solution for a 3D printing lens and a 3D printing device, which can effectively suppress the focal plane shift caused by temperature drift of the 3D printing lens, thereby preventing the deterioration of printing precision and ensuring the stability of imaging resolution in high temperature environment.

[0006] In a first aspect, embodiments of the present application provide a 3D printing lens, which comprises, in order from the object side to the image side along the optical axis:

[0007] a first lens group comprising ≤2 independent glass spherical lenses with an overall optical power φ1<0;

[0008] a second lens group comprising ≤3 independent glass spherical lenses with an overall optical power φ2>0;

[0009] a diaphragm;

[0010] The third lens group comprises independent glass spherical lenses with a number less than 5, and the total optical power φ3>0;

[0011] The imaging chip set comprises a galvanometer, a light splitting prism and an imaging chip.

[0012] All the lenses satisfy:

[0013] The thermal expansion coefficient TCE≤12.7×10 -6 / K;

[0014] The refractive index 1.48≤Nd≤1.81;

[0015] The Abbe number 33.2≤Vd≤81.7;

[0016] The second lens group comprises lenses that can be independently moved, and the back focal distance between the third lens group and the imaging chip is adjustable.

[0017] Optionally, the first lens group, the second lens group and the third lens group form a movable optical lens, and the optical lens is configured to be movable along the optical axis to adjust the back focal distance between the third lens group and the imaging chip.

[0018] The second lens group comprises a third lens, a fourth lens and a fifth lens arranged in sequence along the optical axis, wherein the third lens and the fourth lens close to the first lens group can be moved synchronously along the optical axis to adjust the interval between the first lens group and the third lens.

[0019] Optionally, the projection distance L of the 3D printing lens is 120mm≤L≤160mm.

[0020] The projection ratio TR of the 3D printing lens is ≤0.97.

[0021] The total focal length F of the 3D printing lens is 12mm≤F≤12.4mm.

[0022] Optionally, the first lens group comprises:

[0023] The first lens is a convex-concave negative lens, and the focal length f1 is -63.4mm

[0024] The second lens is a convex-concave negative lens, and the focal length f2 is -59.2mm

[0025] Optionally, the second lens group comprises, in sequence:

[0026] The third lens is a double-convex positive lens, and the focal length f3 is 31mm

[0027] the fourth lens is a convex-concave positive lens, and a focal length f4 of the fourth lens is 44.7mm < f4 < 45.7mm;

[0028] the fifth lens is a convex-concave negative lens, and a focal length f5 of the fifth lens is -18.8mm < f5 < -17.8mm;

[0029] The third lens and the fourth lens are configured to be synchronously movable along the optical axis to approach or move away from the first lens group.

[0030] Optionally, the third lens group comprises, in sequence:

[0031] the sixth lens is a biconvex positive lens, and a focal length f6 of the sixth lens is 17.1mm < f6 < 18.1mm;

[0032] the seventh lens is a biconcave negative lens, and a focal length f7 of the seventh lens is -14.3mm < f7 < -13.3mm;

[0033] the eighth lens is a meniscus positive lens, and a focal length f8 of the eighth lens is 51.6mm < f8 < 52.6mm;

[0034] the ninth lens is a biconvex positive lens, and a focal length f9 of the ninth lens is 32.1mm < f9 < 33.6mm;

[0035] the tenth lens is a biconvex positive lens, and a focal length f10 of the tenth lens is 48mm < f10 < 49mm.

[0036] Optionally, each lens in the 3D printing lens satisfies 2 < φ / T < 6; wherein φ is an optical effective aperture of the lens, and T is a central thickness of the lens.

[0037] An optical total length TTL of the 3D printing lens is less than or equal to 100mm.

[0038] Optionally, the optical total length TTL of the 3D printing lens and the optical effective aperture of the largest lens satisfy 2.5 < TTL / φmax < 3.5.

[0039] Optionally, a focal plane movement D of each lens in the 3D printing lens caused by thermal expansion satisfies D < depth of focus δ.

[0040] Optionally, the 3D printing lens has a telecentricity CRA less than or equal to 0.5°, an optical distortion DO less than or equal to 0.5%, and a TV distortion DTV less than or equal to 0.1%. TV

[0041] Optionally, an air gap A1 between the diaphragm and the second lens group is 10.2mm ~ 10.5mm;

[0042] ​The air gap A2 between the diaphragm and the third mirror group is 3.4mm-3.8mm;

[0043] The aperture of the diaphragm is 4.0mm-4.4mm.

[0044] In a second aspect, the embodiments of the present application provide a 3D printing device, which comprises the 3D printing lens according to the first aspect.

[0045] The beneficial effects of the present application are:

[0046] The 3D printing lens provided by the embodiments of the present application solves the problem of focal plane drift of the 3D printing lens caused by changes in the working environment temperature through the cooperative design of the first mirror group (with negative focal length, diverging light), the second mirror group (with positive focal length, containing double independent moving lenses) and the third mirror group (with positive focal length, adjustable back focal length) arranged along the optical axis, in combination with the glass spherical lens with low thermal expansion coefficient (TCE≤12.7×10 -6 / K), high refractive index (1.48≤Nd≤1.81) and specific Abbe number (33.2≤Vd≤81.7). In particular, the second mirror group can realize the adjustment of focal length by moving some lenses along the optical axis synchronously, and the dynamic adaptation of the back focal length between the third mirror group and the imaging chip ensures clear imaging within the projection distance of 120mm-160mm. Under the combined action of the movement of the first mirror group of-0.215mm to +0.174mm and the back focal adjustment of-0.091mm to +0.111mm, the optimal focal plane temperature drift amount under high temperature (such as 60℃) environment of the 3D printing lens of the present application is ≤0.006mm, while maintaining the high resolution of MTF value≥0.6@93lp / mm, which significantly improves the imaging accuracy and running stability of the 3D printing device, and meets the requirements of high-precision manufacturing scenarios.

[0047] Other features of the present application and its advantages will become apparent from the following detailed description of exemplary embodiments thereof, with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and together with the description, serve to explain the principles of the present application.

[0049] Figure 1 FIG. 1 is one of the structural schematic diagrams of the 3D printing lens according to the embodiments of the present application;

[0050] Figure 2 FIG. 2 is the optical path schematic diagram of the 3D printing lens shown in FIG. 1; Figure 1

[0051] Figure 3 FIG. 3 is the optical path schematic diagram of the 3D printing lens shown in FIG. 2; and Figure 1 ​Spot array diagram of the 3D printing lens shown in FIG. 1;

[0052] Figure 4 For Figure 1 Modulation transfer function diagram of the 3D printing lens shown in FIG. 1;

[0053] Figure 5 For Figure 1 Modulation transfer function (MTF) vs. field diagram of the 3D printing lens shown in FIG. 1;

[0054] Figure 6 For Figure 1 Field curvature and distortion diagram of the 3D printing lens shown in FIG. 1;

[0055] Figure 7 For Figure 1 Relative illumination diagram of the 3D printing lens shown in FIG. 1;

[0056] Figure 8 For Figure 1 Through focus modulation transfer function (Through Focus MTF) diagram of the 3D printing lens shown in FIG. 1 at ambient temperature of 20°C;

[0057] Figure 9 For Figure 1 Through focus modulation transfer function (Through Focus MTF) diagram of the 3D printing lens shown in FIG. 1 at ambient temperature of 60°C;

[0058] Figure 10 For Figure 1 Position diagram of the movable lens in the 3D printing lens shown in FIG. 1;

[0059] Figure 11 For Figure 1 Modulation transfer function diagram of the 3D printing lens shown in FIG. 1 at projection distance of 160 mm;

[0060] Figure 12 For Figure 1 Modulation transfer function diagram of the 3D printing lens shown in FIG. 1 at projection distance of 120 mm;

[0061] Figure 13 For Structure diagram of the 3D printing lens provided by the embodiments of the present application No. 2;

[0062] Figure 14 Figure 13 For Spot array diagram of the 3D printing lens shown in FIG. 1;

[0063] Figure 15 Figure 13 For Modulation transfer function diagram of the 3D printing lens shown in FIG. 1;

[0064] Figure 16 for Figure 13 The relationship between the modulation transfer function (MTF) and field of view of a 3D printed lens is shown in the figure.

[0065] Figure 17 for Figure 13 The field curvature and distortion diagram of the 3D printed lens is shown in the figure;

[0066] Figure 18 for Figure 13 The relative illumination diagram of the 3D printed lens is shown in the image.

[0067] Figure 19 for Figure 13 The graph shows the through-focus MTF of the 3D printed lens at an ambient temperature of 20°C.

[0068] Figure 20 for Figure 13 The graph shows the through-focus MTF of the 3D printed lens at an ambient temperature of 60°C.

[0069] Figure 21 This is a schematic diagram illustrating the TV distortion of a 3D-printed lens provided in an embodiment of this application.

[0070] Explanation of reference numerals in the attached figures:

[0071] 100. First lens group; 101. First lens; 102. Second lens;

[0072] 200. Second lens group; 201. Third lens; 202. Fourth lens; 203. Fifth lens;

[0073] 300. Third lens group; 301. Sixth lens; 302. Seventh lens; 303. Eighth lens; 304. Ninth lens; 305. Tenth lens;

[0074] 400. Imaging chipset; 401. Galvanometer; 402. Beam splitter; 403. Imaging chip;

[0075] 500, aperture. Detailed Implementation

[0076] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0077] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0078] Techniques and devices known to those of ordinary skill in the relevant art can not be discussed in detail, but should be considered part of the specification where appropriate.

[0079] In all of the examples shown and discussed herein, any specific values should be interpreted as merely exemplary and not limiting. Thus, other examples of the exemplary embodiments can have different values.

[0080] It should be noted that like reference numerals and letters refer to like items throughout the drawings, and once an item is defined in one drawing, it need not be discussed further in subsequent drawings.

[0081] The 3D printing lens and the 3D printing device provided by the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0082] According to one embodiment of the present application, a 3D printing lens is provided, referring to Figure 1 and Figure 2 , the 3D printing lens comprises, in order from the object side to the image side along the optical axis, a first lens group 100, a second lens group 200, a diaphragm 500, a third lens group 300, and an imaging chip group 400. The first lens group 100 contains ≤2 independent glass spherical lenses, and the overall optical power φ1<0. The second lens group 200 contains ≤3 independent glass spherical lenses, and the overall optical power φ2>0. The third lens group 300 contains ≤5 independent glass spherical lenses, and the overall optical power φ3>0. The imaging chip group 400 contains a galvanometer 401, a light splitting prism 402, and an imaging chip 403. All lenses in the 3D printing lens satisfy: the thermal expansion coefficient TCE≤12.7×10 -6 / K, the refractive index 1.48≤Nd≤1.81, and the Abbe number 33.2≤Vd≤81.7. Among them, the second lens group 200 contains independently movable lenses, and the back focal distance between the third lens group 300 and the imaging chip 403 is adjustable.

[0083] The 3D printing lens provided by the embodiments of the present application can be applied in a 3D printing device. The 3D printing lens constructs a compact optical structure and a stable optical performance optical system by sequentially arranging the first lens group 100, the second lens group 200, the diaphragm 500, the third lens group 300, and the imaging chip group 400 along the optical axis from the object side to the image side.

[0084] The 3D printing lens provided by the embodiment of the application comprises, from the object side to the image side, a first lens group 100, a second lens group 200, a diaphragm 500, a third lens group 300 and an imaging chip group 400, and the optical components work cooperatively to ensure that the 3D printing lens has stable optical performance. In particular, the optical design of the application can effectively suppress the focal plane shift of the 3D printing lens caused by temperature drift, thereby preventing the deterioration of printing precision and ensuring the stability of imaging resolution in a high-temperature environment.

[0085] The first lens group 100 is designed to contain no more than two independent glass spherical lenses, and the overall optical power of the first lens group 100 is designed to be negative, i.e. φ1 < 0. In the 3D printing lens provided by the application, the first lens group 100 can be used for diverging the incident light.

[0086] In one example, the first lens group 100 is designed to contain two lenses, such as the first lens 101 and the second lens 102 shown in FIG. 1. Figure 1

[0087] Of course, the first lens group 100 can also use one lens, which is not limited in the application.

[0088] The second lens group 200 contains no more than three independent glass spherical lenses, and the overall optical power of the second lens group 200 is designed to be positive, i.e. φ2 > 0. This optical design enables the second lens group 200 to converge light.

[0089] In one example, the second lens group 200 is designed to contain three lenses, such as the third lens 201, the fourth lens 202 and the fifth lens 203 shown in FIG. 2. Figure 1

[0090] Of course, the second lens group 200 can also contain only 1-2 lenses. The number of lenses in the second lens group 200 can be adjusted according to the specific design needs and the coordination relationship with other lens groups, but it is best not to exceed three lenses.

[0091] In particular, the second lens group 200 provided by the application contains independently movable lenses.

[0092] Specifically, the second lens group 200 contains two lenses that can move along the optical axis, such as the third lens 201 and the fourth lens 202 shown in FIG. 3. Figure 1 By moving the third lens 201 and the fourth lens 202 in the second lens group 200, see FIG. 4. Figure 10 ​​The distance between the first mirror group 100 and the third lens 201 along the optical axis can be changed, and the distance between the fourth lens 202 and the fifth lens 203 along the optical axis can also be changed.

[0093] The diaphragm 500 is one of the key optical components in the entire 3D printing lens, and is designed to be located on the optical path between the second mirror group 200 and the third mirror group 300. In this application, the diaphragm 500 is used to control the light flux entering the subsequent mirror group, which can prevent excessive diffusion or improper focusing of light, which is beneficial to improve the imaging quality.

[0094] The third mirror group 300 is designed to include no more than five independent glass spherical lenses, and the optical power of the third mirror group 300 as a whole is also designed to be positive, that is, φ3>0. The third mirror group 300 can also converge light based on the optical power design.

[0095] In one example, the third mirror group 300 is designed to include five lenses, such as Figure 1 The sixth lens 301, the seventh lens 302, the eighth lens 303, the ninth lens 304, and the tenth lens 305 shown in the middle.

[0096] Of course, the number of lenses in the third mirror group 300 can also be flexibly adjusted as needed, preferably no more than five, and the specific number is not limited in this application.

[0097] In the 3D optical machine lens provided in this application, the optical power of the second mirror group 200 and the third mirror group 300 is designed to be positive, and the two work together to converge light. The second mirror group 200 and the third mirror group 300 together form an aberration-corrected optical system that can effectively correct various aberration problems including optical distortion, field curvature, and astigmatism, ensuring that the projected light is highly converged and uniformly distributed, thereby significantly improving image clarity, especially improving the clear image at the edge of the image, thereby improving the overall image quality.

[0098] In this application, a distance adjustment mechanism is specially designed between the third mirror group 300 and the galvanometer 401 in the imaging chip group 400, which can realize the adjustable back focal distance of the entire 3D optical machine lens. The back focal distance here refers to the distance between the lens in the third mirror group 300 close to the imaging chip group 400 and the imaging chip 403 in the imaging chip group 400.

[0099] Specifically, the distance between the third mirror group 300 and the galvanometer 401 in the imaging chip group 400 in the optical axis direction can be controlled by a mechanical driving device, so as to realize the adjustment of the projection distance in the range of 120mm~160mm. It is worth noting that the adjustment process also cooperates with the movement of the aforementioned second mirror group 200 - when the distance between the third mirror group 300 and the galvanometer 401 changes, for example, the distance between the two changes in the range of -0.091mm~+0.111mm, the third lens 201 and the fourth lens 202 in the second mirror group also need to be translated along the optical axis, for example, the moving range is -0.215mm to +0.174mm. This double adjustment mechanism ensures that:

[0100] Projection distance compensation: the adjustment of the back focal distance changes the position of the light convergence point, and the movement of the third lens 201 and the fourth lens 202 in the second mirror group 200 can correct the aberration change caused thereby, so as to maintain a high resolution of MTF≥0.6@93lp / mm within the projection distance of 120mm~160mm;

[0101] Picture size adaptation: through the adjustment of the back focal distance and the cooperative displacement of the second mirror group 200, the scaling of the projection picture size can be realized without changing the total length of the lens (TTL≤100mm) and the focal length changes little, and the optical distortion D0≤0.5% is met. The requirement of image quality;

[0102] Thermal stability guarantee: when the environmental temperature rises from 20℃ to 60℃, the composite adjustment mechanism controls the temperature drift amount of the best focal plane to be ≤0.006mm, which offsets the influence of glass thermal expansion on the imaging quality.

[0103] It should be noted that all the lenses in the present application are independent glass spherical lenses. That is, the 3D optical mechanical lens provided in the present application does not involve a glued mirror group, and each lens is independently arranged.

[0104] The imaging chip group 400 mainly consists of a galvanometer 401, a light splitting prism 402 and an imaging chip 403, as shown in Figure 1 and Figure 2 The imaging chip group 400 is one of the core optical components for the projection imaging function of the 3D printing lens. Among them, the galvanometer 401 is responsible for enhancing the image resolution. The light splitting prism 402 effectively separates the illumination beam and the projection beam. The imaging chip 403 is used to provide the projection light, and finally form a high-quality projection image.

[0105] In the present application, the imaging chip 403 is, for example, a DMD chip, with a size of 0.47 inches and a pixel size of 5.4 microns.

[0106] In the 3D optical machine lens provided in the embodiments of the present application, the parameters such as thermal expansion coefficient (TCE), refractive index (Nd) and Abbe number (Vd) optimized for all the lenses are the key optical parameters for inhibiting the temperature drift effect and ensuring the stability of the optical performance of the lens, and the specific influence mechanism is described as follows.

[0107] (1) Influence of thermal expansion coefficient (TCE) on temperature drift:

[0108] The thermal expansion coefficient (TCE) represents the dimensional stability of a material when the temperature changes. When the temperature of the working environment of the 3D optical machine lens fluctuates, if the TCE of the lens material in the 3D optical machine lens is too large, the geometric dimensions such as the curvature radius and the thickness of the lens will change, thereby causing the focal plane position to deviate (temperature drift).

[0109] In the present application, the thermal expansion coefficient of all the lenses is optimized to be TCE≤12.7×10 -6 / K, which belongs to the category of low expansion glass materials. The size of the lens changes very little when the temperature changes, which can effectively limit the change in the distance or curvature of the lens caused by thermal expansion and contraction, so as to control the focal plane drift within the depth of focus. For example, at a high temperature of 60℃, the focal plane drift is only about 0.006mm, as shown in Figure 8 and Figure 9 , so as to ensure the clarity of the image.

[0110] (2) Regulation of refractive index (Nd) on the stability of optical power:

[0111] The refractive index (Nd) determines the deflection ability of the lens to light. When the temperature rises, the refractive index of the lens material will change due to the thermal effect. If the refractive index (Nd) is too high or too low, it may cause the optical power of the lens to deviate from the design value, thereby causing the image plane position to deviate. The refractive index of the lens is optimized in the present application to satisfy 1.48≤Nd≤1.81. By selecting the material in this interval, the amount of change of the refractive index with temperature and the change of the geometric size of the lens form a compensation effect while ensuring the feasibility of lens processing.

[0112] (3) Abbe number (Vd) for ensuring chromatic aberration and image quality stability:

[0113] The Abbe number (Vd) reflects the dispersion ability of the material to light of different wavelengths. In the present application, 33.2≤Vd≤81.7 is optimized. In the temperature drift scenario, the temperature change may cause the stress distribution in the lens material to change, thereby affecting the dispersion characteristics. By selecting the above Abbe number material, it can be ensured that the dispersion changes very little when the temperature fluctuates, thereby avoiding the deterioration of the image quality caused by the aggravation of the chromatic aberration.

[0114] By optimizing the range of TCE, Nd and Vd, the present application achieves the inhibition of the temperature drift effect of the 3D printing lens. SeeFigure 4 In a high-temperature environment of 60°C, the 3D printing lens can still maintain a resolving power of MTF≥0.6@93lp / mm, and the focal plane drift is only 0.006mm, which is less than the focal depth range (±0.013mm), see Figure 8 and Figure 9 which verifies the effectiveness of the above optical parameter design.

[0115] The 3D printing lens provided by the embodiment of the present application solves the problem of focal plane drift caused by changes in the working environment temperature of the 3D printing lens through the cooperative design of the first lens group 100 (with negative focal power, diverging light), the second lens group 200 (with positive focal power, containing double independently moving lenses) and the third lens group 300 (with positive focal power, adjustable back focal distance) along the optical axis, combined with low thermal expansion coefficient (TCE≤12.7×10 -6 / K), high refractive index (1.48≤Nd≤1.81) and specific Abbe number (33.2≤Vd≤81.7) glass spherical lenses. The second lens group 200 can achieve fine adjustment of focal length by moving some lenses along the optical axis synchronously, and the dynamic adaptation of the back focal distance between the third lens group 300 and the galvanometer 401 ensures clear imaging within a projection distance of 120-160mm. Under the combined action of the movement of the lens group from-0.215mm to +0.174mm and the back focal adjustment from-0.091mm to +0.111mm, the best focal plane temperature drift under high temperature (such as 60°C) environment is ≤0.006mm, while maintaining a high resolving power of MTF value≥0.6@93lp / mm, which significantly improves the imaging accuracy and running stability of the 3D printing equipment, and meets the stringent requirements of high-precision manufacturing scenarios.

[0116] The total focal power of the 3D printing lens of the present application is distributed to three lens groups in a negative-positive-positive structure: the first lens group 100 adopts a negative focal power design, which provides correction space for the light path by diverging light, and the low thermal expansion characteristic of its glass material can inhibit the transmission of front-end temperature drift. The second lens group 200 is configured with positive focal power and introduces independently movable lenses. The third lens group 300 adopts a strong positive focal power design and forms an adjustable back focal structure with the galvanometer 401. In cooperation with the independently movable lenses in the second lens group 200, it ensures that the image plane position deviation is small within a projection distance of 120mm~160mm, for example, <0.006mm (which is only about 46% of the focal depth ±0.013mm), thereby realizing clear imaging.

[0117] The 3D printing lens provided by the embodiment of the present application realizes the following in a temperature range of 20°C to 60°C:

[0118] Image quality stability: MTF value remains≥0.6 at 93lp / mm;

[0119] Compact structure: Total optical length (TTL) < 100mm and projection ratio (TR) ≤ 0.97, meeting the requirements of 3D printing equipment;

[0120] Adjustment compatibility: Through the coordinated adjustment of the second lens group 200 and the back focal distance, the optical system does not need to be recalibrated within the projection distance of 120mm~160mm, which significantly improves printing efficiency.

[0121] See some examples in this application. Figure 10 and Figure 11 The first lens group 100, the second lens group 200 and the third lens group 300 constitute a movable optical lens. The optical lens is configured to move along the optical axis to adjust the back focal distance between the third lens group 300 and the imaging chip 403.

[0122] The second lens group 200 includes a third lens 201, a fourth lens 202 and a fifth lens 203 arranged sequentially along the optical axis. The third lens 201 and the fourth lens 202, which are close to the first lens group 100, can move synchronously along the optical axis to adjust the interval between the first lens group 100 and the third lens 201.

[0123] In the example provided in this application, an adjustable optical lens structure was designed to address the focal plane drift problem caused by temperature changes in 3D printed lenses. (See [link to example]). Figure 10 The optical lens structure mainly consists of three movable lens groups, which achieve dual optimization of projection distance adjustment and thermal stability through mechanical linkage and optical compensation mechanisms.

[0124] In this example, the optical lens as a whole is movable. Specifically, the first lens group 100, the second lens group 200, and the third lens group 300 constitute an integrated optical lens, which can be moved as a whole along the optical axis. This design, by changing the distance between the third lens group 300 and the galvanometer 401, with an adjustment range of, for example, -0.091mm to +0.111mm, helps to adjust the projection distance within the range of 120mm to 160mm. This back focal distance adjustment mechanism can directly control the convergence point of light on the imaging surface, thereby adapting to the needs of different projection distances. For example, when the projection distance increases from 120mm to 160mm, the back focal distance (the distance between the tenth lens 305 in the third lens group 300 and the imaging chip 403 along the optical axis) needs to be shortened accordingly, for example, from 1.66mm to 1.46mm, to ensure that the image remains clear.

[0125] In the second lens group 200 design of the present application, a linkage subunit composed of the third lens 201 (double convex positive lens) and the fourth lens 202 (convex-concave positive lens) is introduced to meet the requirement of adjusting the projection distance.

[0126] For example, when the projection distance increases from 120 mm to 160 mm, the linkage subunit composed of the third lens 201 and the fourth lens 202 moves along the optical axis in the direction of the first lens group 100 (i.e. negative direction). This movement results in a decrease in the optical axis distance between the third lens 201 and the first lens group 100.

[0127] When the back focal distance of the third lens group 300 and the galvanometer 401 changes, the light incidence angle changes, which may cause aberrations such as field curvature and astigmatism. The movement of the third lens 201 and the fourth lens 202 can dynamically correct these aberrations, ensuring that the MTF value is always ≥0.6 at the 93 lp / mm cutoff frequency (especially at high temperature 60°C).

[0128] In some examples of the present application, the projection distance L of the 3D printing lens is 120 mm≤L≤160 mm; the projection ratio TR of the 3D printing lens is ≤0.97; and the total focal length F of the 3D printing lens is 12 mm≤F≤12.4 mm.

[0129] In the present application, the projection distance of the 3D printing lens is in the range of 120 mm≤L≤160 mm. This projection distance range is designed based on the actual application scenarios of 3D printing equipment, covering the projection requirements from small dental models (such as single tooth restorations, with a printing size of about 50 mm×50 mm) to medium-sized mold parts (such as automotive interior parts, with a printing size of about 200 mm×200 mm).

[0130] By adjusting the back focal distance of the third lens group 300 and the imaging chip 403, and the axial position of the double lens (third lens 201 and fourth lens 202) in the second lens group 200, the 3D printing lens can effectively compensate for the image plane position within 120 mm~160 mm.

[0131] For example, at the maximum projection distance of 160 mm, the 3D printing lens provided by the embodiments of the present application can still maintain a resolution of MTF>0.6@93 lp / mm, and the optical distortion D0≤0.5%, ensuring the edge accuracy of large-size printed parts.

[0132] The 3D printing lens provided in the application has a projection ratio (TR) of less than or equal to 0.97. The projection ratio is defined as the ratio of the projection distance to the image width (W). In the application, the TR is compressed to less than or equal to 0.97 through an asymmetric and anti-telephoto optical structure, so that the compatibility of short-focus projection and high resolution is achieved. Compared with a traditional lens (TR is about 1.2 to 1.5), the application can print larger objects at the same projection distance, or high-precision printing can be achieved in a small space.

[0133] The total focal length F of the 3D printing lens provided in the embodiments of the application is 12mm≤F≤12.4mm. The narrow interval design ΔF=0.4mm of the total focal length is the key to balancing the image quality stability and temperature drift suppression.

[0134] In some examples of the application, referring to Figure 1 and Figure 2 , the first lens group 100 includes a first lens 101 and a second lens 102; wherein the first lens 101 is a convex-concave negative lens, and the focal length f1 of the first lens 101 is -63.4mm

[0135] The first lens group 100 is composed of two convex-concave negative lenses, and its main function is to disperse light rays through negative focal power, so as to balance the focal power of other positive lens groups in the optical path.

[0136] Both lenses in the first lens group 100 use low thermal expansion coefficient glass (TCE≤12.7×10 -6 / K). When the temperature rises by 60℃, the size change of the two lenses in the first lens group is very small, which significantly reduces the focal length drift caused by thermal expansion.

[0137] In some examples of the application, referring to Figure 1 and Figure 2 , the second lens group 200 includes a third lens 201, a fourth lens 202 and a fifth lens 203 arranged in sequence; the third lens 201 is a double-convex positive lens, and the focal length f3 of the third lens 201 is 31mm

[0138] The third lens 201 is a double-convex positive lens, and the third lens 201 is used to converge light rays.

[0139] The fourth lens 202 is a convex-concave positive lens, which is used to converge light rays and can correct astigmatism, and the convex-concave structure can balance spherical aberration and coma.

[0140] The fifth lens 203 is a convex-concave negative lens, which diverges part of the light rays through negative focal power, and forms a "positive-positive-negative" combination with the third lens 201 and the fourth lens 202 (both of which are positive lenses), which, in cooperation with the third lens group 300, can optimize the field curvature and optical distortion.

[0141] In the second lens group 200, the third lens 201 and the fourth lens 202 are configured to be synchronously movable along the optical axis, and by adjusting the distance from the first lens group 100, the focal plane drift caused by temperature change or projection distance change can be compensated.

[0142] For example, when the projection distance increases from 120 mm to 160 mm, the two lenses need to move towards the first lens group 100 to reduce the distance from the first lens group 100 to maintain the focusing of light rays on the image plane.

[0143] In the second lens group 200, the three lenses all adopt glass materials with TCE≤12.7×10 -6 At a temperature rise of 60°C, the size change of the three lenses is very small, which reduces the focal power fluctuation caused by thermal expansion.

[0144] The combination of positive and negative lenses reduces the sensitivity of the total focal power of the second lens group 200 to temperature change. For example, when the temperature rises, the decrease in refractive index of the positive lens and the change in curvature radius of the negative lens partially offset each other, maintaining the stability of the focal length of the lens.

[0145] In addition, the second lens group 200 can correct part of the spherical aberration, coma and astigmatism through the positive and negative focal power combination of the three lenses, reducing the correction pressure of the third lens group 300.

[0146] It should be noted that the back focal distance referred to in the present application is the distance between the tenth lens 305 in the third lens group and the imaging chip 403 in the imaging chip group 400 in the direction of the optical axis.

[0147] In some examples of the present application, referring to Figure 1 and Figure 2The third mirror group 300 comprises a sixth lens 301, a seventh lens 302, an eighth lens 303, a ninth lens 304 and a tenth lens 305 arranged in sequence, wherein: the sixth lens 301 is a biconvex positive lens, the focal length f6 of which is 17.1mm < f6 < 18.1mm; the seventh lens 302 is a biconcave negative lens, the focal length f7 of which is -14.3mm < f7 < -13.3; the eighth lens 303 is a meniscus positive lens, the focal length f8 of which is 51.6mm < f8 < 52.6mm; the ninth lens 304 is a biconvex positive lens, the focal length f9 of which is 32.1mm < f9 < 33.6; and the tenth lens 305 is a biconvex positive lens, the focal length f10 of which is 48mm < f10 < 49mm.

[0148] The sixth lens 301 is a biconvex positive lens, responsible for converging light rays. The seventh lens 302 is a biconcave negative lens, which diverges part of the light rays through negative focal power and also optimizes spherical aberration and chromatic aberration. The eighth lens 303 is a meniscus positive lens, which corrects field curvature by using a meniscus structure to make the edge light rays and the center light rays focus at the same position on the image plane. The ninth lens 304 is a biconvex positive lens, which together with the tenth lens 305 forms a focusing group. The tenth lens 305 is a biconvex positive lens, which, for example, improves the light converging ability by using high refractive index material (Nd ≈ 1.81) while suppressing astigmatism.

[0149] The five lenses in the third mirror group 300 are made of glass material with TCE ≤ 12.7 × 10 -6 The size change at 60℃ temperature rise is also small, reducing the focal power fluctuation caused by thermal expansion.

[0150] By adjusting the air gap between the tenth lens 305 and the galvanometer 401 (adjustment range -0.091mm to +0.111mm), the focus plane drift caused by temperature or projection distance change can be compensated, and the optimal focus plane temperature drift is only 0.006mm, as shown in Figure 8 and Figure 9 .

[0151] In some examples of the present application, each lens in the 3D printing lens satisfies 2 < φ / T < 6, wherein φ is the optical effective aperture of the lens, and T is the center thickness of the lens. The total optical length TTL of the 3D printing lens is ≤ 100mm.

[0152] In this example provided by the present application, by constraining the ratio of the optical effective aperture and the center thickness of each lens, such as satisfying 2 < φ / T < 6 and optimizing the total optical length TTL of the entire 3D printing lens to be ≤ 100mm, the optical compactness and small size of the 3D printing lens are realized.

[0153] Optical effective aperture φ refers to the maximum diameter of the area through which the lens participates in imaging light, directly affecting the amount of light entering the lens and the imaging range. The center thickness T is the thickness of the lens at the center position, which together with the thermal expansion coefficient (TCE) of the lens material determines the size change amount under temperature rise.

[0154] The φ / T ratio range is 2<φ / T<6: the lower limit value (φ / T>2) of this design avoids the lens strength being insufficient due to the center thickness being too thin, or deformation caused by thermal stress under temperature rise. The lower limit value (φ / T<6) of this design prevents the center thickness from being too thick, increasing the total optical length TTL of the lens.

[0155] The design of the 3D printing lens provided in the embodiments of the present application has an optical total length TTL≤100mm, which makes the lens adapt to desktop 3D printing equipment and reduces the size of the equipment.

[0156] In some examples of the present application, the optical total length TTL of the 3D printing lens and the optical effective aperture of the largest lens satisfy: 2.5<TTL / φmax<3.5.

[0157] In the example provided in the present application, by controlling the optical total length TTL of the 3D printing lens and the optical effective aperture φmax of the largest lens to satisfy: 2.5<TTL / φmax<3.5, high imaging quality of the 3D printing lens under a compact structure is achieved.

[0158] Optical total length TTL: the axial distance from the first surface of the lens to the imaging chip 403 (such as a DMD chip), reflecting the overall length of the entire 3D printing lens.

[0159] Optical effective aperture φmax of the largest lens: the maximum value of the optical effective aperture of all lenses in the 3D printing lens, determining the radial size and light entering ability of the 3D printing lens.

[0160] In the present application, the TTL / φmax ratio range is 2.5<TTL / φmax<3.5; wherein the lower limit design TTL / φmax>2.5: avoids the optical total length of the 3D printing lens being too short, causing the ten lenses inside to be arranged too densely. The upper limit design TTL / φmax<3.5: prevents the maximum lens diameter from being too large, causing the radial size of the 3D printing lens to exceed the limit or increasing the material cost.

[0161] The 2.5<TTL / φmax<3.5 provided in the example of the present application ensures the balance of the 3D printing lens in the axial and radial sizes. If TTL / φmax<2.5, the lens spacing needs to be compressed or thinner lenses are used. If TTL / φmax>3.5, the radial size of the 3D printing lens is too large, which does not meet the miniaturization requirement of desktop 3D printing equipment.

[0162] In some examples of the present application, the focal plane shift D caused by thermal expansion of each lens in the 3D printing lens satisfies D≤δ.

[0163] The focal plane shift D refers to the displacement of the ideal focal plane of the lens along the optical axis direction caused by thermal expansion of the lens material.

[0164] The focal depth δ refers to the defocus range allowed by the lens on the image plane, within which the imaging quality (such as MTF) still meets the design requirements.

[0165] In the present application, the focal plane shift D≤δ, which ensures that the focal plane drift under high temperature environment does not cause imaging blur, maintaining the printing accuracy.

[0166] The design implementation mechanism in this example of the present application is: the lens is selected to be low-TCE glass to reduce the size change when the temperature rises. Through the non-symmetrical reverse telephoto architecture, the direction of the focal plane shift caused by thermal expansion and the direction of the optical power compensation partially offset each other. For example, the first lens group 100 diverges light, and the second lens group 200 and the third lens group 300 converge light. When the temperature rises, the first lens group 100 moves backward, and the second lens group 200 and the third lens group 300 move forward, and the overall shift is reduced.

[0167] In the present application, the aberration is optimized to increase the allowed defocus range. For example, the focal depth δ≥±0.013mm at room temperature (20℃), and the best focal plane shift D=0.006mm<δ at high temperature (60℃), satisfying D≤δ.

[0168] In some examples of the present application, the 3D printing lens has a telecentricity CRA≤0.5°, an optical distortion D0≤0.5%, and a TV distortion D TV ≤0.1%.

[0169] During the 3D printing process, the size, shape, etc. of the printed object need to be accurately measured and monitored. Low telecentricity means that the chief ray is incident on the imaging plane at a nearly vertical angle. This can minimize the measurement error caused by slight changes in the position of the object, ensuring more accurate size measurement of the printed object at different stages of 3D printing, thereby improving the accuracy of the printed product.

[0170] In the present application, the optical distortion D0≤0.5%, which can ensure that the size deviation of the edge and the center of the printed part is <0.5% (such as 100mm object error <0.5mm).

[0171] TV distortion (D TV ) is used to measure the visual distortion of the image edge. In the present application, D TV ≤0.1%, which is a distortion that cannot be perceived by the human eye, and is suitable for high-precision dental model printing.

[0172] Referring to Figure 21 TV distortion calculation formula is as follows:

[0173]

[0174] TV distortion of the 3D printing lens of the present application satisfies: D TV-k , D TV-h and D TV-v are all ≤0.1%.

[0175] In some examples of the present application, the air gap A1 between the diaphragm 500 and the second lens group 200 is 10.2mm-10.5mm, and the air gap A2 between the diaphragm 500 and the third lens group 300 is 3.4mm-3.8mm. The aperture of the diaphragm is 4.0mm-4.4mm.

[0176] The present application adopts an asymmetric, image-side telecentric architecture: the diaphragm 500 is located between the second lens group 200 and the third lens group 300; wherein the air gap A1 is the distance between the diaphragm 500 and the second lens group 200: 10.2mm-10.5mm; and the air gap A2 is the distance between the diaphragm 500 and the third lens group 300: 3.4mm-3.8mm. By controlling A1 and A2, the light incidence angle and aberration correction are optimized to ensure that the 3D printing lens can maintain high resolving power and low distortion.

[0177] The diaphragm 500 is located in the aperture diaphragm in the optical path of the 3D printing lens, which is used to limit the aperture of the imaging light beam and control the range of light entering the lens, directly affecting the illumination distribution of the image plane and the imaging quality.

[0178] The 3D printing lens of the present application adopts an image-side telecentric architecture, and the chief ray has an incidence angle CRA on the image plane ≤0.5°. Specifically, A1 is larger, making the convergence of the second lens group 200 (positive focal power) on the light more gentle, reducing the sharp change of the chief ray angle. A2 is smaller, making the convergence of the third lens group 300 (positive focal power) on the light more concentrated, further compressing the chief ray angle.

[0179] In addition, the design of A1 and A2 can also realize the compact structure of the 3D printing lens while ensuring the imaging quality.

[0180] The 3D printing lens of the present application is described below by way of Examples 1 and 2.

[0181] Example 1

[0182] Referring to Figure 1 and Figure 2The 3D printing lens provided in Embodiment 1 comprises, in sequence from the object side to the image side along the optical axis, a first lens group 100, a second lens group 200, a diaphragm 500, a third lens group 300 and an imaging chip group 400.

[0183] The first lens group 100 comprises a first lens 101 and a second lens 102, and both the first lens 101 and the second lens 102 are convex-concave negative lenses.

[0184] The second lens group 200 comprises a third lens 201, a fourth lens 202 and a fifth lens 203 arranged in sequence, and the third lens 201 is a biconvex positive lens, the fourth lens 202 is a convex-concave positive lens, and the fifth lens 203 is a convex-concave negative lens.

[0185] The third lens group 300 comprises a sixth lens 301, a seventh lens 302, an eighth lens 303, a ninth lens 304 and a tenth lens 305 arranged in sequence, and the sixth lens 301 is a biconvex positive lens, the seventh lens 302 is a biconcave negative lens, the eighth lens 303 is a meniscus positive lens, the ninth lens 304 is a biconvex positive lens, and the tenth lens 305 is a biconvex positive lens.

[0186] The overall optical power of the first lens group 100 is φ1<0, the overall optical power of the second lens group 200 is φ2>0, and the overall optical power of the third lens group 300 is φ3>0.

[0187] The first lens 101, the second lens 102, the third lens 201, the fourth lens 202, the fifth lens 203, the sixth lens 301, the seventh lens 302, the eighth lens 303, the ninth lens 304 and the tenth lens 305 are all independent glass spherical lenses.

[0188] The imaging chip group 400 comprises a galvanometer 401, a light splitting prism 402 and an imaging chip 403.

[0189] The optical parameters of each lens in the 3D printing lens provided in Embodiment 1 are shown in Table 1 below.

[0190] Table 1

[0191]

[0192] The main parameters of the 3D printing lens provided in Embodiment 1 are shown in Table 2 below.

[0193] Table 2

[0194]

[0195] The projection distance of the 3D printing lens provided in Embodiment 1 is 120mm~160mm, see [link / reference]. Figure 10 By adjusting the air gaps of surfaces 4, 8, and 21 in Table 1, clear imaging can be ensured within the projection distance range. The focal length will also change slightly, such as from 12.0mm to 12.4mm. Specific parameters are shown in Table 3.

[0196] Table 3

[0197]

[0198] The optical performance analysis of the 3D printed lens provided in Example 1 is as follows:

[0199] See Figure 3 , Figure 3 This is a dot array diagram of the 3D printed lens in Embodiment 1. Figure 3 It can be seen that: Spot (RMS) < 0.5 Pixel.

[0200] See Figure 4 , Figure 4 This is the modulation transfer function (MTF) diagram of the 3D printed lens in Embodiment 1. Figure 4 It can be seen that MTF > 0.7 @ 93 lp / mm.

[0201] See Figure 5 , Figure 5 This is a graph showing the relationship between the modulation transfer function (MTF) and field of view of the 3D-printed lens in Embodiment 1. It reflects the MTF values ​​of the 3D-printed lens under different fields of view (Y-axis in millimeters). The green line represents a spatial frequency of 30 line pairs / mm (lp / mm), and the blue line represents a spatial frequency of 93 lp / mm. Figure 5 As can be seen, the MTF value is relatively stable across the entire field of view, without any drastic fluctuations. This indicates that the lens exhibits good consistency in image sharpness across different field-of-view positions.

[0202] At 30 lp / mm (green line), the MTF value remains at a high level, close to 1.0, with minimal fluctuations throughout the entire field of view. This indicates that at this spatial frequency, the lens can effectively transmit contrast information across the entire field of view, resulting in clear imaging.

[0203] For 93 lp / mm (blue line), although the MTF value fluctuates somewhat, it remains at a relatively high level overall. The MTF value is above 0.8 in most fields of view, with only a slight decrease at some points in the field of view, but the decrease is not significant. This indicates that even at higher spatial frequencies, the lens can still maintain good image quality and has high resolution capabilities.

[0204] Referring to Figure 6 , Figure 6 the distortion map and the field curvature map of the 3D printing lens of this embodiment 1, it can be seen that the optical distortion DO < 0.5%. Figure 6

[0205] Referring to Figure 7 , Figure 7 the relative luminance of the 3D printing lens of this embodiment 1, it can be seen that the relative luminance > 94%. Figure 7

[0206] Referring to Figure 8 and Figure 9 , the best focal plane temperature drift amount of the 3D printing lens of this embodiment 1 is only 0.006mm, indicating that the temperature drift effect is well inhibited.

[0207] Referring to Figure 11 and Figure 12 , the MTF of the 3D printing lens of this embodiment 1 is > 0.7@93lp / mm when the projection distance is 160mm and 120mm.

[0208] Embodiment 2

[0209] Referring to Figure 13 , the 3D printing lens provided in this embodiment 2 comprises, in order from the object side to the image side along the optical axis, a first lens group 100, a second lens group 200, a diaphragm 500, a third lens group 300 and an imaging chip group 400;

[0210] The first lens group 100 comprises a first lens 101 and a second lens 102, and both the first lens 101 and the second lens 102 are convex-concave type negative lenses;

[0211] The second lens group 200 comprises a third lens 201, a fourth lens 202 and a fifth lens 203 arranged in order, and the third lens 201 is a double-convex type positive lens, the fourth lens 202 is a convex-concave type positive lens, and the fifth lens 203 is a convex-concave type negative lens;

[0212] The third lens group 300 comprises a sixth lens 301, a seventh lens 302, an eighth lens 303, a ninth lens 304 and a tenth lens 305 arranged in order, and the sixth lens 301 is a double-convex type positive lens, the seventh lens 302 is a double-concave type negative lens, the eighth lens 303 is a meniscus type positive lens, the ninth lens 304 is a double-convex type positive lens, and the tenth lens 305 is a double-convex type positive lens;

[0213] The overall optical power of the first lens group 100 is φ1 < 0, the overall optical power of the second lens group 200 is φ2 > 0, and the overall optical power of the third lens group 300 is φ3 > 0.​​

[0214] The first lens 101, the second lens 102, the third lens 201, the fourth lens 202, the fifth lens 203, the sixth lens 301, the seventh lens 302, the eighth lens 303, the ninth lens 304 and the tenth lens 305 are all independent glass spherical lenses;

[0215] The imaging chip group 400 includes a galvanometer 401, a beam splitter 402, and an imaging chip 403.

[0216] The third lens 201 and the fourth lens 202 can move along the optical axis;

[0217] The first mirror group 100, the second mirror group 200 and the third mirror group 300 can move along the optical axis to adjust the distance between the third mirror group 300 and the galvanometer 401.

[0218] In this embodiment 2, the lens is not moved, and its projection distance is 140mm.

[0219] The optical parameters of each lens in the 3D printed lens provided in this embodiment 2 are shown in Table 4 below.

[0220] Table 4

[0221]

[0222] The main parameters of the 3D printed lens provided in this embodiment 2 are shown in the table below.

[0223] Table 5

[0224]

[0225] The optical performance analysis of the 3D printed lens provided in Example 2 is as follows:

[0226] See Figure 14 , Figure 14 This is a dot array diagram of the 3D printed lens in Embodiment 2. Figure 14 It can be seen that: Spot (RMS) < 0.5 Pixel.

[0227] See Figure 15 , Figure 15 This is the modulation transfer function (MTF) diagram of the 3D printed lens in Embodiment 2. Figure 15 It can be seen that MTF > 0.69 @ 93 lp / mm.

[0228] See Figure 16 , Figure 16The modulation transfer function (MTF) vs. field of view (Field) graph of the 3D printing lens of Embodiment 2 reflects the MTF values of the 3D printing lens at different field of view (Y axis in millimeters), in which the dark blue represents the spatial frequency of 30 line pairs per millimeter (lp / mm), and the light blue line represents the spatial frequency of 93 lp / mm. Overall, the MTF values of the two curves maintain a relatively high and stable level within the entire field of view range, and the 3D printing lens has good transmission capability for image information of different spatial frequencies at different field of view positions, and has high imaging clarity and good uniformity. The two curves have small fluctuations, indicating that the performance stability of the lens at different field of view positions is good. This means that the imaging quality can be maintained relatively consistent whether in the central field of view or the edge field of view of the lens, and there will be no large fluctuations in imaging quality due to changes in the field of view.

[0229] 30 lp / mm (dark blue line): The MTF value is close to 1.0 within the entire field of view range, indicating that the lens can clearly present the main structures and contours in the image, meeting the needs of accurate imaging of the basic shape and characteristics of the object in 3D printing.

[0230] 93 lp / mm (light blue line): This is a higher spatial frequency corresponding to fine details in the image. It also maintains a high MTF value, although it fluctuates slightly compared to the dark blue line, but the overall still maintains a high level. This indicates that the lens has high resolution and can well transmit the fine details in the image. For the fine structure and texture details that need to be accurately presented in 3D printing, it can ensure high imaging quality.

[0231] Referring to Figure 17 , Figure 17 The distortion and field curvature graphs of the 3D printing lens of Embodiment 2 show that Figure 17 The optical distortion D0 is less than 1%.

[0232] Referring to Figure 18 , Figure 18 The relative luminance of the 3D printing lens of Embodiment 2 shows that Figure 18 The relative luminance is greater than 97%.

[0233] Referring to Figure 19 and Figure 20 , the best focal plane temperature drift of the 3D printing lens of Embodiment 2 is still relatively small, indicating that the temperature drift effect is still well suppressed.

[0234] According to another embodiment of the present application, a 3D printing device is provided, which comprises the 3D printing lens as described above.

[0235] The specific implementation of the 3D printing device of the embodiments of the present application can refer to the above-mentioned embodiments of the 3D printing lens, and therefore at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0236] The focus of the above embodiments is the difference between the various embodiments. The different optimization features between the various embodiments can be combined to form a better embodiment as long as they are not contradictory. Considering the brevity of the writing, it will not be described here.

[0237] Although some specific embodiments of the present application have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A 3D printing lens characterized by, In order from the object side to the image side along the optical axis, successively comprising: A first lens group (100) comprising a first lens (101) with negative focal power and a second lens (102) with negative focal power, the overall focal power of the first lens group (100) being φ1<0; A second lens group (200) comprising a third lens (201) with positive focal power, a fourth lens (202) with positive focal power, and a fifth lens (203) with negative focal power, the overall focal power of the second lens group (200) being φ2>0; A diaphragm (500); A third lens group (300) comprising a sixth lens (301) with positive focal power, a seventh lens (302) with negative focal power, an eighth lens (303) with positive focal power, a ninth lens (304) with positive focal power, and a tenth lens (305) with positive focal power, the overall focal power of the third lens group (300) being φ3>0; An imaging chip group (400) comprising a galvanometer (401), a light splitting prism (402), and an imaging chip (403); Wherein, all the lenses are independent glass spherical lenses, and satisfy: Thermal expansion coefficient TCE ≤ 12.7 x 10 -6 / K; Refractive index 1.48≤Nd≤1.81; Abbe number 33.2≤Vd≤81.7; The second lens group (200) comprises independently movable lenses, and the back focal distance between the third lens group (300) and the imaging chip (403) is adjustable.

2. The 3D printing lens of claim 1, wherein, The first lens group (100), the second lens group (200), and the third lens group (300) form a movable optical lens, which is configured to be movable along the optical axis to adjust the back focal distance between the third lens group (300) and the imaging chip (403); The second lens group (200) comprises the third lens (201), the fourth lens (202), and the fifth lens (203) arranged in order along the optical axis, wherein the third lens (201) and the fourth lens (202) close to the first lens group (100) can be moved synchronously along the optical axis to adjust the interval between the first lens group (100) and the third lens (201).

3. The 3D printing lens of claim 2, wherein, The projection distance L of the 3D printing lens is 120mm≤L≤160mm; The projection ratio TR of the 3D printing lens is ≤0.97; The total focal length F of the 3D printing lens is 12mm≤F≤12.4mm.

4. The 3D printing lens of claim 1, wherein, The first lens (101) in the first lens group (100) is a convex-concave negative lens, and the focal length f1 is -63.4mm The second lens (102) in the first lens group (100) is a convex-concave negative lens, and the focal length f2 is -59.2mm 5. The 3D printing lens of claim 1, wherein, The third lens (201) in the second lens group (200) is a double-convex positive lens, and the focal length f3 is 31mm The fourth lens (202) in the second lens group (200) is a convex-concave positive lens, and the focal length f4 is 44.7mm The fifth lens (203) in the second lens group (200) is a convex-concave type negative lens, and the focal length f5 is -18.8mm < f5 < -17.8mm. The third lens (201) and the fourth lens (202) are configured to be able to move synchronously along the optical axis to approach or move away from the first lens group (100).

6. The 3D printing lens of claim 1, wherein, The sixth lens (301) in the third lens group (300) is a biconvex type positive lens, and the focal length f6 is 17.1mm < f6 < 18.1mm. The seventh lens (302) in the third lens group (300) is a biconcave type negative lens, and the focal length f7 is -14.3mm < f7 < -13.

3. The eighth lens (303) in the third lens group (300) is a meniscus type positive lens, and the focal length f8 is 51.6mm < f8 < 52.6mm. The ninth lens (304) in the third lens group (300) is a biconvex type positive lens, and the focal length f9 is 32.1mm < f9 < 33.

6. The tenth lens (305) in the third lens group (300) is a biconvex type positive lens, and the focal length f10 is 48mm < f10 < 49mm.

7. The 3D printing lens of claim 1, wherein, The lenses in the 3D printing lens satisfy 2 < φ / T < 6; wherein φ is the optical effective aperture of the lens, and T is the center thickness of the lens. The total optical length TTL of the 3D printing lens is ≤100mm.

8. The 3D printing lens according to claim 7, wherein, The total optical length TTL of the 3D printing lens and the maximum optical effective aperture φmax satisfy 2.5 < TTL / φmax < 3.

5.

9. The 3D printing lens of claim 1, wherein, The focal plane movement D caused by thermal expansion of the lenses in the 3D printing lens satisfies D ≤ focal depth δ.

10. The 3D printing lens of claim 1, wherein, The 3D printing lens has a telecentricity CRA≤0.5°, an optical distortion D0≤0.5%, and a TV distortion D TV ≤0.1%.

11. The 3D printing lens of claim 1, wherein, The air gap A1 between the diaphragm (500) and the second lens group (200) is 10.2mm~10.5mm; The air gap A2 between the diaphragm (500) and the third lens group (300) is 3.4mm~3.8mm; The aperture of the diaphragm (500) is 4.0mm~4.4mm.

12. A 3D printing device, characterized by The 3D printing lens according to any one of claims 1-11. The 3D printing lens according to any one of claims 1-11.

Images