Zero-distortion ultra-high-definition lens applied to DLP 3D printing

Abstract

The utility model provides a zero-distortion ultra-high-definition lens applied to DLP 3D printing, and relates to the technical field of optics. Comprising a first lens group, a diaphragm, a second lens group, a galvanometer, a light splitting device, protective glass and an imaging surface which are arranged in sequence, the imaging surface is used for emitting light rays, the protective glass is used for preventing dust from falling onto the imaging surface and the light splitting device, the galvanometer is used for adjusting imaging pixels, the light splitting device is used for splitting the light rays, and the diaphragm is used for controlling the light inlet amount of the split light rays. The first group lens and the second group lens are both used for correcting aberration; the DLP 3D printing objective lens solves the problems that in the prior art, a DLP 3D printing objective lens is large in distortion, imaging is not clear enough, and cost is too high.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of photocuring 3D printing, in particular to a zero-distortion ultra-high definition lens applied to DLP 3D printing. BACKGROUND

[0002] 3D printing technology, as a kind of rapid prototyping technology, realizes the pursuit of people to efficient, fine, personalized and customized products by its special production and manufacturing method. Up to now, the technology has not only provided model patterns for the industry design or mechanical manufacturing industry. Its application approaches involve jewelry, food, industrial design, building, engineering, automobile, aerospace, medical industry, education, geographic information system, civil engineering, military and other fields. The principle of photocuring 3D printing technology is that the activation energy generated by ultraviolet light with the highest energy in the light spectrum can break the C-C bond of unsaturated polyester resin, generate free radicals and thus solidify the resin.

[0003] At present, photocuring 3D printing technology is mainly divided into SLA (laser point source photocuring), DLP (projector area source curing) and LCD (liquid crystal area source curing) three ways, among which DLP type photocuring 3D printing technology has been widely applied due to its high precision and high efficiency.

[0004] DLP 3D printing photocuring technology adopts UV LED illumination DMD surface, and forms printing by imaging the DMD surface to the photocuring surface through a projection lens. With the improvement of the printing precision requirement of parts, the image quality and distortion of the projection lens are also correspondingly improved.

[0005] Most of the existing DLP 3D printing objective lenses have large distortion, and for high-precision printing occasions, the objective lens system needs to have low distortion or even achieve zero distortion, and the imaging quality of the objective lens also has very high requirements. In addition, the existing DLP 3D printing objective lens cannot simultaneously ensure low distortion and ultra-high definition imaging quality when aiming at different working distances, at which time the objective lens system needs to be redesigned and processed, thereby increasing the development cost of the objective lens. UTILITY MODEL CONTENT

[0006] In order to overcome the shortcomings of the prior art, the utility model aims at providing a zero-distortion ultra-high definition lens applied to DLP 3D printing. The utility model solves the problems of large distortion of the DLP 3D printing objective lens in the prior art, unclear imaging and high cost.

[0007] In order to achieve the above-mentioned purpose, the utility model provides the following scheme.

[0008] A zero-distortion ultra-high definition lens applied to DLP 3D printing comprises:

[0009] The first lens group, the diaphragm, the second lens group, the galvanometer, the light splitting device, the protective glass and the imaging surface are arranged in sequence.

[0010] The imaging surface is used for emitting light, the protective glass is used for preventing dust from falling on the imaging surface and the light splitting device, the galvanometer is used for adjusting the imaged pixels, the light splitting device is used for splitting the light, the diaphragm is used for controlling the light quantity of the split light, and the first lens group and the second lens group are used for correcting aberration.

[0011] The first lens group comprises a first lens, a second lens and a third lens, the first lens and the second lens are lenses with negative focal length, and the third lens is a lens with positive focal length.

[0012] The second lens group comprises a fourth lens, a fifth lens and a sixth lens.

[0013] The sixth lens is a lens with positive focal length, and the fourth lens and the fifth lens constitute a double-cemented lens with negative focal length.

[0014] The first lens, the second lens and the third lens are all arranged in front of the diaphragm, and the fourth lens, the fifth lens and the sixth lens are all arranged behind the diaphragm.

[0015] Preferably, the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the galvanometer, the light splitting device and the protective glass are all made of glass.

[0016] Preferably, the second lens and the sixth lens are both aspherical lenses.

[0017] The utility model discloses the following technical effects:

[0018] The utility model provides a kind of zero-distortion ultra-high-definition lens applied to DLP 3D printing, comprising: first lens group, diaphragm, second lens group, galvanometer, light splitting device, protective glass and imaging surface are sequentially arranged;The imaging surface is used to emit light, the protective glass is used to prevent dust from falling into the imaging surface and light splitting device, the galvanometer is used to adjust the pixel of imaging, the light splitting device is used to split the light, the diaphragm is used to control the light quantity of the light after splitting, the first lens group and the second lens group are used to correct aberration;The first lens group includes: first lens, second lens and third lens, the first lens and the second lens are both negative power lens, and the third lens is positive power lens;The second lens group includes: fourth lens, fifth lens and sixth lens;The sixth lens is positive power lens, and the fourth lens and the fifth lens constitute double cemented lens with negative power;The first lens, the second lens and the third lens are all placed in front of the diaphragm, and the fourth lens, the fifth lens and the sixth lens are all placed behind the diaphragm.The utility model discloses 3D printing projection lens, total length is little, distortion is extremely low, satisfy the demand of desktop level high accuracy 3D printing equipment, the utility model discloses 3D printing projection lens can be compatible with XPR technology, when using XPR, realize 4K resolution, when not using XPR, realize 1080P resolution, the utility model discloses 3D printing projection lens, full field of view MTF is higher than 0.79, distortion is less than 0.003%, can realize super high definition zero distortion high quality imaging, the utility model discloses 3D printing projection lens, when aiming at different working distance, only need to change the air interval between lenses to satisfy the high quality imaging standard, be favorable to improve the flexibility of objective lens in use range and reduce the cost of objective lens development, the utility model discloses 3D printing projection lens, the lens all adopts glass material, can effectively avoid the problem that 405nm short wave light source energy is strong because of 3D printing, and plastic aspherical surface is easy to heat and leads to serious running focus, the first lens uses meniscus lens, can reduce the field angle of light incident to the subsequent system, is helpful to the distortion and coma of system, the utility model discloses 3D printing projection lens, point list diagram light spot radius (<2um) is far less than image element size (5.4um), and the application advantage is obvious for 3D printing, which emphasizes light spot size and energy concentration degree, the utility model discloses 3D printing projection lens, the transmittance of the selected lens material to 405nm wavelength light is higher, all exceeds 95% / 10mm, and the lens quantity is less, only 6, and the energy absorption of whole imaging system is very small, is helpful to improve the brightness of system, reduces the heating of whole projection system, is favorable to improve the stability of 3D printing, the utility model discloses 3D printing projection lens, the design wavelength is 395nm, 405nm, 410nm, includes the wavelength fluctuation of actual light source, makes the lens design more close to the actual situation, the utility model discloses 3D printing projection lens, only uses 6 lenses, compared with other ten or so lenses of lens design, effectively reduces the lens cost and assembly difficulty. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical scheme in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0020] Figure 1 A zero-distortion ultra-high-definition lens structure schematic diagram applied to DLP 3D printing is provided for the embodiments of the present application.

[0021] Figure 2The objective lens Layout diagram when the working distance d=140mm is provided for the embodiment of the utility model;

[0022] Figure 3 The first spatial frequency MTF diagram is provided for the embodiment of the utility model;

[0023] Figure 4 The first point column diagram is provided for the embodiment of the utility model;

[0024] Figure 5 The first field curvature evaluation diagram is provided for the embodiment of the utility model;

[0025] Figure 6 The first distortion evaluation diagram is provided for the embodiment of the utility model;

[0026] Figure 7 The first relative luminance diagram is provided for the embodiment of the utility model;

[0027] Figure 8 The objective lens Layout diagram when the working distance d=200mm is provided for the embodiment of the utility model;

[0028] Figure 9 The second spatial frequency MTF diagram is provided for the embodiment of the utility model;

[0029] Figure 10 The second point column diagram is provided for the embodiment of the utility model;

[0030] Figure 11 The second field curvature evaluation diagram is provided for the embodiment of the utility model;

[0031] Figure 12 The second distortion evaluation diagram is provided for the embodiment of the utility model;

[0032] Figure 13 The second relative luminance diagram is provided for the embodiment of the utility model;

[0033] Figure 14 The objective lens Layout diagram when the working distance d=300mm is provided for the embodiment of the utility model;

[0034] Figure 15 The third spatial frequency MTF diagram is provided for the embodiment of the utility model;

[0035] Figure 16 The third point column diagram is provided for the embodiment of the utility model;

[0036] Figure 17 The third field curvature evaluation diagram is provided for the embodiment of the utility model;

[0037] Figure 18The third distortion evaluation diagram provided by the embodiment of the utility model;

[0038] Figure 19 The third relative luminance diagram provided by the embodiment of the utility model.

[0039] Mark explanation:

[0040] 1 - first lens group, 2 - second lens group, 3 - diaphragm, 4 - galvanometer, 5 - light splitting device, 6 - protective glass, 7 - imaging surface, G1 - first lens, GM2 - second lens, G3 - third lens, G4 - fourth lens, G5 - fifth lens, GM6 - sixth lens. Specific implementation

[0041] The technical scheme in the embodiments of the utility model will be described clearly and completely in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the utility model.

[0042] In order to make the above-mentioned purpose, features and advantages of the utility model more obvious and easy to understand, the utility model will be further described in detail in combination with the drawings and specific implementation.

[0043] As Figure 1 The utility model provides a kind of zero distortion ultra-high definition lens applied to DLP 3D printing, further, comprising:

[0044] sequentially arranged first lens group 1, diaphragm 3, second lens group 2, galvanometer 4, light splitting device 5, protective glass 6 and imaging surface 7;

[0045] The imaging surface 7 is used to emit light, the protective glass 6 is used to prevent dust from falling into the imaging surface 7 and light splitting device 5, the galvanometer 4 is used to adjust the pixel of imaging, the light splitting device 5 is used to split the light, the diaphragm 3 is used to control the light quantity of split light, the first lens group and the second lens group are used for correcting aberration;

[0046] The first lens group includes: first lens G1, second lens GM2 and third lens G3, the first lens G1 and the second lens GM2 are both lenses with negative focal length, and the third lens G3 is a lens with positive focal length;

[0047] The second lens group includes: fourth lens G4, fifth lens G5 and sixth lens GM6;

[0048] The sixth lens GM6 is a lens with positive optical power, and the fourth lens G4 and the fifth lens G5 constitute a cemented doublet lens with negative optical power.

[0049] The first lens G1, the second lens GM2, and the third lens G3 are all placed in front of the aperture stop 3, and the fourth lens G4, the fifth lens G5, and the sixth lens GM6 are all placed behind the aperture stop 3.

[0050] Specifically, such as Figure 1 As shown. G1, GM2, G3, G4, G5, GM6, galvanometer 4, beam splitter 5, and protective glass 6 are all made of glass.

[0051] The first lens group is located in front of aperture stop 3. The first lens in the first group is a lens with negative optical power, the second lens is a lens with negative optical power, and the third lens is a lens with positive optical power.

[0052] The second lens group is located after aperture stop 3. The first lens in the second group is a cemented doublet with negative optical power. The combination of G4 and G5 as a cemented doublet is beneficial for chromatic aberration correction and reducing tolerance sensitivity. The second lens is a lens with positive optical power. GM6 is set as an aspherical surface, which is beneficial for spherical aberration and coma correction.

[0053] Figure 1 S1, S2, S3, S4, S5, and S6 represent the air gaps between the lenses, which can be changed when the objective lens is used at different working distances. At the same time, the focal length of the objective lens system will also change.

[0054] Furthermore, both the second lens GM2 and the sixth lens GM6 are aspherical lenses.

[0055] The ratio of the focal length of the first lens G1 to the focal length of the first lens group ranges from -1.135 to -1.306; the ratio of the focal length of the second lens GM2 to the focal length of the first lens group ranges from -0.741 to -0.736; the ratio of the focal length of the third lens G3 to the focal length of the first lens group ranges from 0.736 to 0.741; the ratio of the focal length of the cemented doublet with negative optical power to the focal length of the second lens group ranges from -115.982 to -115.972; and the ratio of the focal length of the sixth lens GM6 to the focal length of the second lens group is less than 1.157.

[0056] Specifically, each lens must meet the following requirements:

[0057] 4.18 <f1 / f<4.21;

[0058] -1.315 <fG1 / f1<-1.306;

[0059] -0.741 < fGM2 / f1 < -0.736;

[0060] 0.736 < fG3 / f1 < 0.741;

[0061] 2.067 < f2 / f < 2.085;

[0062] -115.982 < fG4G5 / f2 < -115.972;

[0063] fGM6 / f2 < 1.157;

[0064] f is focal length; f1 is focal length of the first group 1; fG1 is focal length of the lens G1; fGM2 is focal length of the aspheric lens GM2; fG3 is focal length of the lens G3; f2 is focal length of the second group 2; fG4G5 is focal length of the double cemented lens G4G5; fGM6 is focal length of the aspheric lens GM6.

[0065] In particular, the surface serial numbers 1 to 12 represent the surfaces of each lens from the first spherical lens to the sixth aspheric lens in order; the serial number STOP represents the stop 3 surface; the serial number OBJ represents the object; the surface serial numbers 13, 14 represent the galvanometer 4 surfaces; the surface serial numbers 15, 16 represent the prism surfaces; the surface serial numbers 17, 18 represent the protective glass 6 surfaces; the serial number IMA represents the image surface; the aspheric coefficients of the second aspheric lens and the sixth aspheric lens are shown in Table 1; the air gaps S1-S6 between the lenses have their respective preferred solutions in the specific embodiments of the objective lens for different working distances d, which will be described below.

[0066] Table 1 is a table of aspheric lens GM2 and GM6 coefficients of each order, which is shown as follows:

[0067] Table 1 is a table of aspheric lens GM2 and GM6 coefficients of each order, which is shown as follows:

[0068]

[0069] In particular, when the working distance d = 140 mm, the parameters of the air gaps S1-S6 between the lenses are shown in the following table:

[0070] Table 2 is a table of the parameters of the air gaps S1-S6 between the lenses when the working distance d = 140 mm

[0071]

[0072] As shown in Figure 2 , the focal length of the lens is 11.962 mm, the FOV is 62.59°, and the F / NO is 1.875.

[0073] Further, asFigure 3 As shown in the figure, the MTF (English name: Modulation Transfer Function) index is the most accurate and scientific evaluation standard for the lens. The ordinate (Modulus of the OTF) is the contrast, and the closer to 1, the better the lens imaging. The abscissa (Spatial Frequency in cycles per mm) represents the resolution, with the unit of each millimeter line logarithm. The pixel size of the image source used in the embodiment of the application is 5.4 um, and the corresponding design resolution is 93 lines per millimeter. The projection lens generally requires that the MTF value of each field of view reaches at least 0.3 in design, and in the embodiment, the MTF value of each field of view is more than 0.79.

[0074] As shown in the figure, Figure 4 The smaller the spot radius of each field of view, the better the imaging quality it represents. Generally, the full-field RMS is less than the pixel size (5.4 um), which belongs to an excellent level. And the full-field RMS of the embodiment is less than 2.0 um, which belongs to a very excellent level.

[0075] As shown in the figure, Figures 5-6 As shown in the figure, Figure 5 is a field curvature evaluation graph, Figure 6 is a distortion evaluation graph. The ordinate represents the field angle of the lens. The abscissa of the field curvature graph represents the field curvature value with the unit of mm (Millimeters), and the abscissa of the distortion graph represents the distortion with the unit of percent (Percent). Distortion is a very important index of the projection lens. The embodiment is suitable for a severe distortion use scenario. The system distortion of the embodiment is within 0.0005%, and the TV distortion is within 0.0002%. The system distortion and the TV distortion are extremely small, and the objective lens can be considered as zero distortion.

[0076] Figure 7 is a lens relative illumination graph. The ordinate represents the relative illumination (Relative Illumination), and the abscissa represents the image height with the unit of mm (Millimeters). As shown in the figure, the relative illumination at the maximum image height of the lens reaches 94%, so that the uniformity of the projection effect of the system imaging surface 7 will be very good.

[0077] Further, when the working distance d = 200 mm, the air gap S1-S6 between each lens has the parameters shown in the following table:

[0078] Table 4 Parameters of air gap S1-S6 between each lens when working distance d = 200 mm

[0079]

[0080] As shown in the figure,Figure 8 As shown in the figure, the focal length of the lens is 11.914mm, the FOV is 60.22°, and the F / NO is 1.876.

[0081] As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent. Figure 9

[0082] As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent. Figure 10 As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent.

[0083] Figures 11-12 As shown in the figure, Figure 11 is a field curvature evaluation figure, Figure 12 is a distortion evaluation figure. The ordinate represents the field angle of the lens. The abscissa of the field curvature figure represents the size of the field curvature value, and the abscissa of the distortion figure represents the distortion amount. Distortion is a very important indicator of a projection lens; this embodiment is suitable for a severe distortion use scenario, and the system distortion of this embodiment is within 0.0012%, and the TV distortion amount is within 0.0002%, and the system distortion and TV distortion are extremely small, and the objective lens can be considered to be zero distortion.

[0084] As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent. Figure 13

[0085] When the working distance d=300mm, the air gap S1~S6 between each lens has the following table parameters:

[0086] Table 5 Parameters of air gap S1~S6 between each lens when working distance d=300mm:

[0087]

[0088] As shown in the figure, the focal length of the lens is 11.914mm, the FOV is 60.22°, and the F / NO is 1.876. Figure 14 As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent.

[0089] Figure 15 As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent.

[0090] As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent. Figure 16 As shown in the figure, the MTF value of each field of view is higher than 0.79 at 93lp / mm, and the resolution is extremely excellent.

[0091] Figures 17-18 As shown in the figure, Figure 17 is a field curvature evaluation figure, Figure 18 ​​​​​For distortion evaluation chart. The ordinate represents the field angle of the lens. The abscissa of the field curvature chart represents the size of the field curvature value, and the abscissa of the distortion chart represents the distortion. Distortion is a very important indicator of the projection lens; the system distortion of the embodiment is within 0.003%, and the TV distortion is within 0.0002%, and the system distortion and the TV distortion are extremely small, so the objective lens can be considered as zero distortion.

[0092] As shown in Figure 19 , the edge illumination reaches 92%, so that the uniformity performance of the projection effect of the system imaging surface 7 will be very good.

[0093] Further, the lens MTF is greater than 0.79, which can realize super high definition imaging; the lens can realize high-quality imaging only by changing the air spacing of each lens when used at different working distances; the lens adopts a 0.47-inch DMD chip; the relative illumination of the lens is high, which is conducive to improving the light-mechanical uniformity; the selected lens material has a high transmittance to light at a wavelength of 405 nm.

[0094] Further, in the embodiment, the optical lens satisfies the following conditional expression:

[0095] 1.5<|fg3 / fG1GM2|<1.55 (1)

[0096] Wherein, fG3 represents the focal length of the lens G3, and fg1GM2 represents the combined focal length of the lenses G1 and GM2.

[0097] In the embodiment, the optical lens satisfies the following conditional expression:

[0098] 1.74< CURV2 / CURV1<1.92 (2)

[0099] Wherein, CURV2 represents the curvature of the 2nd surface of the lens G1, and CURV1 represents the curvature of the 1st surface of the lens G1.

[0100] When the conditional expression (2) is satisfied, the processing capability and the aberration correction capability of the lens G1 can be reasonably balanced. When the value of CURV2 / CURV1 exceeds the lower limit, the lens will be difficult to process; when the value of CURV2 / CURV1 exceeds the upper limit, the aberration correction capability of the lens will decrease.

[0101] In the embodiment, the optical lens satisfies the following conditional expression:

[0102] CRA<1.5° (3)

[0103] Wherein, CRA represents the chief ray incidence angle of the optical lens at the imaging surface 7.

[0104] When the conditional expression (3) is satisfied, the DMD chip can be well matched, and a good projection effect can be achieved.

[0105] In an embodiment, the optical lens satisfies the following conditional expression:

[0106] 13.5°< RAID3 <15° (4)

[0107] Wherein, RAID3 represents the incident angle of the chief ray of the full field of view on the surface of the stop 3.

[0108] When the conditional expression (4) is satisfied, if the value of RAID3 exceeds the lower limit, it is not conducive to the first group to correct the spherical aberration and distortion; if the value of RAID3 exceeds the upper limit, it is not conducive to the second group to correct the coma, spherical aberration and distortion.

[0109] In an embodiment, the second group of the objective lens adopts the combination of G4G5 double cemented lens + aspherical lens GM6.

[0110] The various embodiments in the specification are described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

[0111] The principle and implementation mode of the present application are described by using specific examples in this specification, and the above description of the embodiments is only used to help understand the method and core idea of the present application; at the same time, for the general technical personnel in the art, according to the idea of the present application, the specific implementation mode and application range will be changed. In conclusion, the content of the specification should not be understood as a limitation of the present application.

Claims

1. A zero-distortion ultra-high-definition lens applied to DLP 3D printing, characterized in that, The application relates to a lens device. The lens device comprises a first lens group, a diaphragm, a second lens group, a vibrating mirror, a light splitting device, a protective glass and an imaging surface arranged in sequence. The imaging surface is used for emitting light, the protective glass is used for preventing dust from falling on the imaging surface and the light splitting device, the vibrating mirror is used for adjusting the pixels of the image, the light splitting device is used for splitting the light, the diaphragm is used for controlling the light quantity of the split light, and the first lens group and the second lens group are used for correcting aberration. The first lens group comprises a first lens, a second lens and a third lens, the first lens and the second lens are lenses with negative focal length, and the third lens is a lens with positive focal length. The second lens group comprises a fourth lens, a fifth lens and a sixth lens. The sixth lens is a lens with positive focal length, and the fourth lens and the fifth lens constitute a double-cemented lens with negative focal length. The first lens, the second lens and the third lens are arranged in front of the diaphragm, and the fourth lens, the fifth lens and the sixth lens are arranged behind the diaphragm.

2. The zero-distortion ultra-high-definition lens applied to DLP 3D printing according to claim 1, characterized in that, The first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the vibrating mirror, the light splitting device and the protective glass are all made of glass.

3. The zero-distortion ultra-high-definition lens applied to DLP 3D printing according to claim 1, characterized in that, The second lens and the sixth lens are aspherical lenses.

4. The zero-distortion ultra-high-definition lens applied to DLP 3D printing according to claim 1, characterized in that, The first lens uses a meniscus lens.

Images