Projection lens

Abstract

The invention relates to a projection lens, which comprises a first lens with diopter, a second lens with diopter, a third lens with diopter, a fourth lens with diopter and a fifth lens with diopter which are sequentially arranged from the magnification side of the projection lens to the reduction side of the projection lens, at least one of the second lens, the third lens, the fourth lens and the fifth lens is a gradual change refractive index lens, and the gradual change refractive index lens accords with 0.6 gt; t / Dgt; t is the thickness of the graded-index lens on the center, and D is the maximum outer diameter of the graded-index lens; and the aperture is arranged between the second lens and the reduction side of the projection lens, the value of the total diopter of the lenses with diopter between the aperture and the reduction side is positive, and the number of the lenses with diopter of the projection lens is less than 12.

Description

Technical Field

[0001] The present invention relates to a projection technology, and in particular to a projection lens used in a projector, a micro projector, a TV wall and the like. Background Art

[0002] In the past, most projectors were liquid crystal (LCD) projectors, which were relatively large in size. In recent years, as digital light processing (DLP) technology has become extremely mature, it uses a digital micro-mirror device (DMD, Digital Micro-mirror Device, also known as a light valve), which greatly reduces the size of the projector. However, the extent to which the size of the conventional projection lens can be reduced is relatively limited. This is because optical lenses always have various aberrations that cause image distortion, such as chromatic aberration. In the past, the method of eliminating chromatic aberration usually used glued lenses. The technology was mature, but the disadvantage was that two or more lenses were used, resulting in a larger size, and the cost was higher due to the large number of lenses used. Therefore, how to reduce the size of the projection lens of a light valve projector is an urgent problem that needs to be solved in this technical field.

[0003] To this end, the applicant has worked hard to propose the "projection lens" of the present invention, which uses non-homogeneous materials to manufacture lenses to achieve the same achromatic effect without using glued lenses, or uses non-homogeneous materials to further enhance the achromatic effect of glued lenses. Summary of the invention

[0004] In order to reduce the size of the lens, the projection lens provided by the present invention uses two or more materials to manufacture an inhomogeneous achromatic lens to achieve the optical characteristics of a gradient refractive index to become a gradient refractive index lens, thereby replacing a cemented lens. This inhomogeneity is different from the homogeneity of a traditional lens. Traditional lenses are made of homogeneous materials, so the refraction effect is achieved through curved surfaces; the gradient refractive index lens of the present invention uses the inhomogeneous distribution of two or more materials to achieve the effect of refraction when light travels through them. Usually, a lens is made of two materials with different densities and different doping. Since the cemented lens is larger (usually thicker), if a gradient refractive index lens is used instead,To reduce the volume of the lens (element) or lens group (group) with achromatic function. Furthermore, the surface shape of this gradient refractive index lens can be a flat lens, or it can have a spherical or aspherical structure, or the surface has a diffraction structure, or it can have an anti-curved characteristic. The direction of the gradient refractive index can be radial or radial and axial. In addition, the total refractive power of the lens group between the aperture and the image reduction side of the projection lens is positive. As for the lenses between the aperture and the image magnification side of the projection lens, at least one is an aspherical lens. In addition, the aperture value of the projection lens is between 1.35 and 2.5. In addition, the gradient refractive index lens can also be used as one of the lenses in the cemented lens. The ΔNd value of the gradient refractive index lens meets the following conditions: ΔNd≤Ndmax-Ndmin<0.24, where Ndmax is the maximum Nd value of the gradient refractive index lens, and Ndmin is the minimum Nd value of the gradient refractive index lens, and the Nd value is the refractive index of the gradient refractive index lens at the helium d-line (helium yellow line, wavelength 587.56nm). In this way, the volume of the projection lens can be further reduced, and the effect of achromatism can be maintained or even improved.

[0005] Therefore, in order to achieve the above-mentioned object, the present invention provides a projection lens, comprising: a first lens with refractive power, a second lens with refractive power, a third lens with refractive power, a fourth lens with refractive power and a fifth lens with refractive power are arranged in sequence from the magnification side of the projection lens to the reduction side of the projection lens, wherein at least one of the second lens, the third lens, the fourth lens and the fifth lens is a gradient refractive index lens, and the gradient refractive index lens satisfies 0.6>T / D>0.035, wherein T is the thickness of the gradient refractive index lens at the center, and D is the maximum outer diameter of the gradient refractive index lens; and an aperture is provided between the second lens and the reduction side of the projection lens, and the sum of the refractive powers of the lenses with refractive power between the aperture and the reduction side is positive, wherein the number of lenses with refractive power in the projection lens is less than 12.

[0006] In order to achieve the above-mentioned object, the present invention further provides a projection lens, comprising: a first lens with refractive power, a second lens with refractive power, a third lens with refractive power, a fourth lens with refractive power and a fifth lens with refractive power are arranged in sequence from the magnification side of the projection lens to the reduction side of the projection lens; an aperture is arranged between the second lens and the reduction side of the projection lens; and the sum of the refractive powers of the lenses with refractive power between the aperture and the reduction side is positive; at least one of the second lens, the third lens, the fourth lens and the fifth lens is a lens with refractive power on a curved surface and inhomogeneous materials on both surfaces, and the inhomogeneous material lens on both surfaces meets 0.6>T / D>0.035, wherein T is the thickness of the inhomogeneous material lens on the optical axis of the projection lens, and D is the maximum outer diameter of the inhomogeneous material lens; and the number of lenses with refractive power in the projection lens is less than 12.

[0007] In order to achieve the above-mentioned object, the present invention further provides a projection lens, comprising: a first lens with refractive power, a second lens with refractive power, a third lens with refractive power, a fourth lens with refractive power and a fifth lens with refractive power are arranged in sequence from the magnification side of the projection lens to the reduction side of the projection lens; one of the second lens, the third lens, the fourth lens and the fifth lens is a flat lens with refractive power and a smooth surface without microstructures, and the flat lens satisfies 0.6>T / D>0.035, T is the thickness of the flat lens, and D is the maximum outer diameter of the flat lens; an aperture is provided between the second lens and the reduction side, and the sum of the refractive powers of the lenses with refractive power between the aperture and the reduction side is positive; and the number of lenses with refractive power in the projection lens is less than 12.

[0008] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the following specifically cites a preferred embodiment and describes it in detail with the accompanying drawings as follows. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above objects and advantages of the present invention will become more immediately apparent to those skilled in the art after referring to the following detailed description and the accompanying drawings.

[0010] Figure 1 is a schematic diagram of a lens according to embodiment 1 of the present invention.

[0011] Figure 2 is a schematic diagram of a lens according to embodiment 2 of the present invention.

[0012] Figure 3is a schematic diagram of a lens according to embodiment 3 of the present invention.

[0013] Figure 4 is a schematic diagram of a lens according to embodiment 4 of the present invention.

[0014] Figure 5 is a schematic diagram of a lens according to embodiment 5 of the present invention.

[0015] Figure 6 is a schematic diagram of a lens according to embodiment 6 of the present invention.

[0016] Figure 7 is a schematic diagram of a lens according to embodiment 7 of the present invention.

[0017] Figure 8 is a schematic diagram of a lens according to embodiment 8 of the present invention.

[0018] Fig. 9 is a schematic diagram of a lens according to Embodiment 9 of the present invention.

[0019] Fig.10 It is an MTF diagram according to embodiment 10 of the present invention.

[0020] Fig.11 is a schematic diagram of a lens according to embodiment 11 of the present invention.

[0021] Fig.12 is a schematic diagram of a lens according to embodiment 12 of the present invention.

[0022] Fig.13 is a schematic diagram of a lens according to embodiment 13 of the present invention.

[0023] Fig.14 is a schematic diagram of a lens according to embodiment 14 of the present invention.

[0024] Fig.15 is a schematic diagram of a lens according to embodiment 15 of the present invention.

[0025] Fig.16 is a schematic diagram of a lens according to embodiment 16 of the present invention.

[0026] Fig.17 is a schematic diagram of a lens according to embodiment 17 of the present invention.

[0027] Fig.18 is a schematic diagram of a lens according to embodiment 18 of the present invention.

[0028] Fig.19 is a schematic diagram of a lens according to embodiment 19 of the present invention.

[0029] Fig. 20 is a schematic diagram of a lens according to embodiment 20 of the present invention.

[0030] Fig.21 It is an MTF diagram according to Example 1 of the present invention.

[0031] Fig. 22 It is an MTF diagram according to Example 9 of the present invention.

[0032] Fig.23 It is an MTF diagram according to embodiment 10 of the present invention.

[0033] Fig.24 It is an MTF diagram according to embodiment 20 of the present invention. DETAILED DESCRIPTION

[0034] The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the detailed description of the embodiments with reference to the drawings below. The directional terms mentioned in the following embodiments, such as: up, down, left, right, front or back, etc., are only referenced to the directions of the attached drawings. Therefore, the directional terms used are used to illustrate and not to limit the present invention. In addition, the terms "first" and "second" used in the following embodiments are used to identify the same or similar elements and are not used to limit the elements.

[0035] The optical element in the present invention refers to an element that is partially or completely made of a reflective or transmissive material, usually glass or plastic, such as a lens, a prism or an aperture.

[0036] When the lens is used in an imaging system, the image magnification side refers to the side closer to the object on the optical path, and the image reduction side refers to the side closer to the photosensitive element on the optical path.

[0037] The object-side surface (or image-side surface) of a lens has a convex portion (or concave portion) located in a certain area, which means that the area is more "convex outwardly" (or "concave inwardly") in a direction parallel to the center than the outer area adjacent to the area in the radial direction.

[0038] The following is a summary table of the embodiments used in the present invention, wherein "EFL: effective focal length", "F / # or Fno: aperture", "TTL: length from the first lens to the last optical lens on the optical axis of the projection lens", "IMH: image height of half field of view angle", "D1: first lens diameter", "DL: last lens diameter", "FOV: field of view angle", "BFL: distance from the last optical lens to the light valve", "Δnd is ndmax-ndmin, where ndmax is the maximum nd value of the progressive refractive lens, and ndmin is the minimum nd value of the progressive refractive lens, that is, Δnd is the maximum nd value of the progressive refractive lens minus ndmin, which is the minimum nd value of the progressive refractive lens", "T / D: ratio of thickness (T) to outer diameter (D) of the variable refractive lens", "f1: EFL from the first lens to sto (aperture)", "f2: EFL from sto (aperture) to the last lens", and "EX1-EX20: Example 1-Example 20".

[0039] Summary table 1:

[0040]

[0041]

[0042] Summary table 2:

[0043]

[0044]

[0045] See also Figure 1, is a schematic diagram of a lens according to Example 1 (EX1) of the present invention. The lens 1 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 1 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS (object side) is also called the aperture front, also called forward or front; the aperture 14 toward the image reduction side IS (image side) is also called the aperture rear, also called backward or rear. And behind the seventh lens L7 are the optical path adjustment mechanism 16, the prism 18, the protective lens 10, and the light valve 4 in order. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group (also called the front group) 20 with positive refractive power (f1 value in Table 2 EX1), that is, the lens group in front of the aperture 14; the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 constitute a second lens group (also called the rear group) 30 with positive refractive power (f2 value in Table 2 EX1), that is, the lens group behind the aperture. In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, negative, negative, positive, and positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the fifth lens L5 is a material inhomogeneous lens with a gradient refractive index, and is a flat lens. A gradient refractive index lens is an optical lens in which the refractive index distribution of the internal material gradually changes along the radial or axial direction. A material inhomogeneous lens, also known as a material inhomogeneous lens or an inhomogeneous material lens, refers to a lens using materials containing different refractive indices. The material of the lens closest to the image magnifying side OS can be made of glass. The image magnifying side OS of each specific embodiment of the present invention is respectively arranged on the left side of each figure, that is, the left side of the aperture 14, and the image reducing side IS is arranged on the right side of each figure, that is, the right side of the aperture 14, which will not be described in detail.

[0046] The aperture 14 referred to in the present invention refers to an aperture stop, which can be an independent component or integrated into other optical components. In this embodiment, the aperture uses a mechanism to block peripheral light and retain the light transmission in the middle to achieve a similar effect, and the aforementioned mechanism can be adjustable. The so-called adjustable refers to the adjustment of the position, shape or transparency of the mechanism. Alternatively, the aperture can also be coated with an opaque light-absorbing material on the surface of the lens, and retain the light transmission in the central part to achieve the effect of limiting the light path.

[0047] Most of the inhomogeneous lenses in this case have radially gradient refractive index, that is, the direction of change of the inhomogeneity of the material is radial. The refractive index calculation formula is as follows: n(r) = n 00 +C 10 r 2 +C 20 r 4+C 30 r 6 +C 40 r 8 Where n is the refractive index, r is the radius, and n(r) represents the refractive index of an inhomogeneous lens with a radius r of a certain value; n 00 is the basic refractive index; C i0 (C 10 , C 20 , C 30 , C 40 …) represent the correlation coefficients. Table 1 of the following embodiments will reveal the basic parameters of the lens design corresponding to the figure, and Table 2 of the following embodiments will reveal the design parameters of the inhomogeneous lens (gradient refractive index lens) corresponding to the figure. Table 2 shows the values ​​of the basic refractive index and the correlation coefficients at different wavelengths of light, where the C-line in the horizontal column is the wavelength of the hydrogen C line (hydrogen red line) light 656.27nm, the d-line is the wavelength of the helium d line (helium yellow line) 587.56nm, the F-line is the wavelength of the hydrogen F line (hydrogen blue line) 486.13nm, and the vertical column is n 00 is the basic refractive index; C 10 , C 20 , C 30 , C 40 In addition, the ΔNd value of the gradient refractive index lens must meet the following conditions: ΔNd = Ndmax-Ndmin<0.24, where Ndmax is the maximum Nd value of the gradient refractive index lens, and Ndmin is the minimum Nd value of the gradient refractive index lens, and the Nd value is the refractive index of the gradient refractive index lens at the helium d-line (wavelength 587.56nm), and Figure 1 The ΔNd of the fifth lens L5 is less than 0.1015. Table 3 of each embodiment discloses the parameters of the aspherical lens therein.

[0048] Table 1 of Example 1 (EX1):

[0049]

[0050]

[0051] Table 2 of Example 1 (EX1):

[0052]

[0053] Table 3 of Example 1 (EX1):

[0054] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 18.049 9.3173E-04 -1.0468E-05 7.2743E-08 7.5990E-10 0 0 S2 -0.593 -8.6075E-05 4.4846E-05 -1.5426E-06 2.6806E-08 0 0 S3 -99.000 -3.3934E-03 1.5754E-04 -4.8534E-06 6.5320E-08 0 0 S4 -20.509 -9.1962E-04 9.3823E-05 -3.1780E-06 5.0831E-08 0 0

[0055] The spacing of S1 is the distance between the surface S1 and S2 at the center 12 , the spacing of S2 is the distance between the surface S2 and S3 at the center 12 , and so on. The spacing of S20 is the thickness of the protective lens 10 .

[0056] The surfaces marked with * in the table are non-homogeneous lenses (gradient index lenses), while surfaces without this mark are homogeneous lenses.

[0057] The radius of curvature is the inverse of the curvature. When the radius of curvature is positive, the center of the sphere on the lens surface is on the image reduction side of the lens. When the radius of curvature is negative, the center of the sphere on the lens surface is on the image magnification side of the lens. The convexity and concavity of each lens can be seen in the table above.

[0058] The structure and function of the optical path adjustment mechanism 16 in the embodiment of the present invention can be referred to the following patents: Taiwan, China I584045, Taiwan, China I613503, Taiwan, China I670518, China CN 207366814U, Taiwan, China I657307, Taiwan, China I629504, Taiwan, China I641899, Taiwan, China M554179, Taiwan, China I767947, Taiwan, China I744445, Taiwan, China I737875, Taiwan, China I691778, Taiwan, China I798391, etc.

[0059] See also Figure 2 , is a schematic diagram of a lens according to Example 2 (EX2) of the present invention. The lens 2 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 1 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and an eighth lens L8 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called forward or front; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called backward or rear. And behind the eighth lens L8 are the optical path adjustment mechanism 16, the prism 18, and the protective lens 10 in sequence. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group 20 with negative refractive power, i.e., the lens group before the aperture 14 (also called the front group); the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7 and the eighth lens L8 constitute a second lens group 30 with positive refractive power, i.e., the lens group after the aperture (also called the rear group). In this embodiment, the refractive powers of the first lens L1 to the eighth lens L8 are negative, negative, positive, positive, negative, positive, positive, positive, positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the sixth lens L6 is an inhomogeneous lens with a gradient refractive index and a flat lens. The material of the lens closest to the image magnification side OS can be made of glass.

[0060] Table 1 of Example 2 (EX2):

[0061]

[0062] Table 2 of Example 2 (EX):

[0063]

[0064]

[0065] Table 3 of the second embodiment:

[0066] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 99.000 8.3079E-04 -1.1166E-05 1.1526E-07 7.1609E-10 0 0 S2 -0.395 -6.4861E-05 3.0453E-05 -1.8398E-06 4.2546E-08 0 0 S3 -99.000 -3.3545E-03 1.3271E-04 -4.1932E-06 6.4277E-08 0 0 S4 -13.873 -1.0776E-03 9.0614E-05 -2.7841E-06 4.4305E-08 0 0

[0067] See also Figure 3 , is a schematic diagram of a lens according to Example 3 (EX3) of the present invention. The lens 3 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 1 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called forward or front; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called backward or rear. And behind the seventh lens L7 are the optical path adjustment mechanism 16, the prism 18, and the protective lens 10 in sequence. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group 20 (also called the front group) with positive refractive power, that is, the lens group in front of the aperture 14; the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 constitute a second lens group 30 (also called the rear group) with positive refractive power, that is, the lens group behind the aperture. In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, negative, positive, positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The material of the lens closest to the image magnification side OS can be made of glass.

[0068] Table 1 of Example 3 (EX3):

[0069]

[0070]

[0071] Table 2 of Example 3 (EX3):

[0072]

[0073] Table 3 of Example 3 (EX3):

[0074] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 0.000 3.5598E-04 -4.3861E-06 5.7887E-08 7.9321E-11 0 0 S2 0.000 -1.3897E-04 -6.3734E-06 -2.4591E-07 0 0 0 S3 0.000 -3.9344E-04 -1.0927E-06 1.2977E-07 0 0 0 S4 -10.405 -4.0495E-04 6.9803E-06 -3.0324E-08 0 0 0

[0075] See also Figure 4 , is a schematic diagram of a lens according to Example 4 (EX4) of the present invention. The lens 4 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 4 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called forward or front; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called backward or rear. And behind the seventh lens L7 are the optical path adjustment mechanism 16, the prism 18, and the protective lens 10 in sequence. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group (also called a front group) 20 with negative refractive power, i.e., the lens group in front of the aperture 14; the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 constitute a second lens group (also called a rear group) 30 with positive refractive power, i.e., the lens group behind the aperture. In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, positive, negative, positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the sixth lens L6 is an inhomogeneous lens with a gradient refractive index and a flat lens. The material of the lens closest to the image magnification side OS can be made of glass.

[0076] Table 1 of Example 4 (EX4):

[0077]

[0078]

[0079] Table 2 of Example 4 (EX4):

[0080]

[0081] Table 3 of Example 4 (EX4):

[0082] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 0 9.1152E-04 -5.7211E-06 -9.8957E-08 2.0581E-09 0 0 S2 0 -4.7065E-04 6.5683E-05 -1.3493E-06 0 0 0 S3 0.228 -6.6977E-03 3.1525E-04 -9.1302E-06 1.0408E-07 0 0 S4 -5.244 -2.2864E-03 1.6165E-04 -5.4303E-06 7.5785E-08 0 0

[0083] See also Figure 5, is a schematic diagram of a lens according to Example 5 (EX5) of the present invention. The lens 5 has a lens barrel (not shown) with an image magnification side OS and an image reduction side IS. The lens 5 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called forward or front; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called backward or rear. And behind the seventh lens L7 are the optical path adjustment mechanism 16, the prism 18, and the protective lens 10 in sequence. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group 20 with positive refractive power, i.e., the lens group before the aperture 14 (also called the front group); the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 constitute a second lens group 30 with positive refractive power, i.e., the lens group after the aperture (also called the rear group). In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, positive, negative, positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the sixth lens L6 is an inhomogeneous lens with a gradient refractive index, and is a curved lens, which can be a spherical surface, an aspherical surface, or a lens with a diffractive structure. The material of the lens closest to the image magnification side OS can be made of glass.

[0084] Table 1 of Example 5 (EX5):

[0085]

[0086]

[0087] Table 2 of Example 5 (EX5):

[0088]

[0089] Table 3 of Example 5 (EX5):

[0090] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 0 7.9732E-04 -5.5024E-06 -3.2362E-08 8.1821E-10 0 0 S2 0 -4.6538E-06 3.6819E-05 -7.0446E-07 0 0 0 S3 1.085 -6.4268E-03 3.0127E-04 -9.2390E-06 1.1759E-07 0 0 S4 -4.484 -2.4581E-03 1.8882E-04 -6.8356E-06 1.0458E-07 0 0

[0091] See also Figure 6, is a schematic diagram of a lens according to Example 6 (EX6) of the present invention. The lens 6 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 1 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6 and a seventh lens L7 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called the forward or front group; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called the rear or rear group. And behind the seventh lens L7 are the optical path adjustment mechanism 16, the prism 18, and the protective lens 10 in sequence. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group 20 with negative refractive power, i.e., the lens group before the aperture 14 (also called the front group); the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 constitute a second lens group 30 with positive refractive power, i.e., the lens group after the aperture (also called the rear group). In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, negative, negative, positive, positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index, and is a curved lens, which can be a spherical surface, an aspherical surface, or a lens with a diffractive structure. The material of the lens closest to the image magnification side OS can be made of glass. The curved lens is defined to have a maximum outer diameter. The maximum outer diameter refers to the distance between the outermost mirror turning points of the curved surface at both ends of the optical axis in the direction perpendicular to the optical axis.

[0092] Table 1 of Example 6 (EX6):

[0093]

[0094]

[0095] Example 6 (EX6) Table 2:

[0096]

[0097] Table 3 of Example 6 (EX6):

[0098] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 0 8.5123E-04 -6.8691E-06 -4.4272E-08 1.4974E-09 0 0 S2 0 -5.8616E-04 5.7233E-05 -1.4184E-06 0 0 0 S3 0.176 -6.7318E-03 3.1829E-04 -9.3873E-06 1.1360E-07 0 0 S4 -7.151 -2.5270E-03 1.6840E-04 -5.3066E-06 7.3528E-08 0 0

[0099] See also Figure 7 , is a schematic diagram of a lens according to Example 7 (EX7) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the ninth lens L9 are negative, negative, positive, negative, negative, positive, positive, positive, negative, positive, respectively, and the first lens L1 is an aspheric lens, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0100] Table 1 of Example 7 (EX7):

[0101]

[0102]

[0103] Example 7 (EX7) Table 2:

[0104]

[0105]

[0106] Table 3 of Example 7 (EX7):

[0107] surface K A^4 B^6 C^8 D^10 E^12 S1 -54.61 7.4603E-04 -1.4782E-05 2.7736E-07 -2.7672E-09 1.26236E-11 S2 0.305 7.9149E-04 -7.9462E-06 -1.0483E-06 5.6610E-08 0

[0108] See also Figure 8 , is a schematic diagram of a lens according to Example 8 (EX8) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the tenth lens L10 are negative, negative, negative, positive, positive, negative, positive, negative, positive, negative, positive, positive, respectively, and the first and tenth lenses (L1, L10) are aspherical lenses, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0109] Table 1 of Example 8 (EX8):

[0110]

[0111]

[0112] Example 8 (EX8) Table 2:

[0113]

[0114] Table 3 of Example 8 (EX8):

[0115] surface K A^4 B^6 C^8 D^10 E^12 F^14 S1 0.453 -1.0952E-05 7.8631E-08 -1.7105E-10 3.1151E-13 0 0 S2 -1.060 1.5360E-05 -1.5141E-08 7.8304E-10 7.3209E-12 0 0 S18 -2.948 6.0681E-07 2.2566E-08 0 0 0 0 S19 -14.168 7.4524E-06 3.7912E-08 0 0 0 0

[0116] See also Fig. 9, is a schematic diagram of a lens according to Example 9 (EX9) of the present invention. The lens 9 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 7 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called the forward or front group; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called the rear or rear group. And behind the sixth lens L6 are the aperture 14, the optical path adjustment mechanism 16, the prism 18, the protective lens 10, and the light valve 4 in order. The first lens L1 to the sixth lens L6 constitute a first lens group 20 with negative refractive power, i.e., the lens group in front of the aperture 14 (also referred to as the front group); the seventh lens L7 to the eleventh lens L11 constitute a second lens group 30 with positive refractive power, i.e., the lens group behind the aperture (also referred to as the rear group). In this embodiment, the refractive powers of the first lens L1 to the eleventh lens L11 are respectively negative, negative, negative, positive, positive, positive, positive, negative, positive, negative, positive, negative, positive, positive, and positive. The first and second lenses (L1, L2) are aspherical lenses, and the sixth lens L6 is an inhomogeneous lens with a gradient refractive index and a flat plate structure. The material of the lens closest to the image magnification side OS can be made of glass.

[0117] Table 1 of Example 9 (EX9):

[0118]

[0119]

[0120] Table 2 of Example 9 (EX9):

[0121]

[0122] Table 3 of Example 9 (EX9):

[0123] surface K A^4 B^6 C^8 D^10 E^12 S1 -26.345 2.3321E-05 -3.1918E-08 2.9927E-11 -1.6175E-14 4.08511E-18 S2 -0.781 -8.3574E-05 6.8520E-07 -2.3814E-09 4.2356E-12 -4.01162E-15 S3 -2.526 -1.3457E-04 9.0283E-07 -2.7825E-09 3.0162E-12 0 S4 -0.656 -6.9272E-05 3.4070E-07 2.5720E-09 -8.7548E-12 0

[0124] See also Fig.10, is a schematic diagram of a lens according to Example 10 (EX10) of the present invention. The lens 10 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 1 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, and a sixth lens L6 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, also called the forward or front group; the aperture 14 toward the image reduction side IS is also called the aperture rear, also called the rear or rear group. And behind the sixth lens L6 are the prism 18, the protective lens 10, and the light valve 4 in order. Please refer to the previous description for the relevant functions. The first lens L1, the second lens L2 and the third lens L3 constitute a first lens group 20 with negative refractive power, i.e., the lens group before the aperture 14 (also called the front group); the fourth lens L4, the fifth lens L5 and the sixth lens L6 constitute a second lens group 30 with positive refractive power, i.e., the lens group after the aperture (also called the rear group). In this embodiment, the refractive powers of the first lens L1 to the sixth lens L6 are negative, negative, positive, negative, positive, positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index, a flat plate structure, and a cemented lens, i.e., cemented with the fifth lens L5. The material of the lens closest to the image magnification side OS can be made of glass.

[0125] Table 1 of Example 10 (EX10):

[0126]

[0127]

[0128] Table 2 of Example 10 (EX10):

[0129]

[0130] Table 3 of Example 10 (EX10):

[0131] surface K A^4 B^6 C^8 D^10 S1 -1.902 -6.6133E-04 1.2046E-05 -7.8123E-08 1.5552E-09 S2 -0.802 -2.4877E-03 1.2371E-05 -1.8422E-06 4.4542E-08 S3 -0.802 -3.4955E-04 -1.2048E-05 1.1069E-05 -2.7457E-07 S4 -0.716 4.2313E-04 3.8094E-05 4.2255E-06 -7.8784E-08

[0132] See also Fig.11 , is a schematic diagram of a lens according to Example 11 (EX11) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the fifth lens L5 are negative, positive, negative, positive, and positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the fifth lens L5 is an inhomogeneous lens with a gradient refractive index and a biconvex lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0133] Table 1 of Example 11 (EX11):

[0134]

[0135]

[0136] Table 2 of Example 11 (EX11):

[0137]

[0138] Table 3 of Example 11 (EX11):

[0139] surface K A^4 B^6 C^8 D^10 E^12 S1 0 2.0819E-03 -6.0588E-05 1.7145E-06 -2.6980E-08 1.9837E-10 S2 0 2.5407E-03 -5.1252E-05 1.4710E-06 1.4772E-08 0 S3 0 -6.2205E-04 -3.8178E-05 1.2390E-06 -8.9067E-08 0 S4 0 -2.8579E-04 -1.4870E-04 3.3222E-05 -3.4452E-06 0

[0140] See also Fig.12 , is a schematic diagram of a lens according to Example 12 (EX12) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the ninth lens L9 are negative, negative, positive, negative, negative, positive, negative, positive, positive, respectively, and the second lens L2 is an aspheric lens, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0141] Table 1 of Example 12 (EX12):

[0142]

[0143]

[0144] Table 2 of Example 12 (EX12):

[0145]

[0146]

[0147] Table 3 of Example 12 (EX12):

[0148] surface K A^4 B^6 C^8 D^10 E^12 S3 -2.10 -9.3315E-04 1.8574E-05 -2.1725E-07 1.3985E-09 -3.7498E-12 S4 -0.927 -1.9837E-03 3.7730E-05 -5.6276E-07 4.6818E-09 -1.6879E-11

[0149] See also Fig.13 , is a schematic diagram of a lens according to Example 13 (EX13) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the ninth lens L9 are negative, negative, positive, negative, negative, positive, negative, positive, positive, respectively, and the second lens L2 is an aspheric lens, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0150] Table 1 of Example 13 (EX13):

[0151]

[0152]

[0153] Table 2 of Example 13 (EX13):

[0154]

[0155] Table 3 of Example 13 (EX13):

[0156] surface K A^4 B^6 C^8 D^10 E^12 S3 -2.146 -9.4355E-04 1.8549E-05 -2.1265E-07 1.3423E-09 -3.5683E-12 S4 -0.951 -2.0918E-03 4.0853E-05 -5.9593E-07 4.9061E-09 -1.7668E-11

[0157] See also Fig.14 , is a schematic diagram of a lens according to Example 14 (EX14) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the eighth lens L8 are negative, negative, positive, positive, negative, positive, positive, positive, respectively, and the second lens L2 is an aspheric lens, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0158] Table 1 of Example 14 (EX14):

[0159]

[0160]

[0161] Table 2 of Example 14 (EX14):

[0162]

[0163] Table 3 of Example 14 (EX14):

[0164] surface K A^4 B^6 C^8 D^10 E^12 S3 -1.790 -6.5959E-04 1.1114E-05 -1.0274E-07 5.0391E-10 -9.8034E-13 S4 -0.907 -1.6988E-03 2.3404E-05 -2.7101E-07 1.6581E-09 -4.5045E-12

[0165] See also Fig.15 , is a schematic diagram of a lens according to Example 15 (EX15) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the eighth lens L8 are negative, negative, positive, positive, negative, positive, positive, positive, respectively, and the second lens L2 is an aspheric lens, and the third lens L3 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0166] Table 1 of Example 15 (EX15):

[0167]

[0168]

[0169] Table 2 of Example 15 (EX15):

[0170]

[0171] Table 3 of Example 15 (EX15):

[0172] surface K A^4 B^6 C^8 D^10 E^12 S3 -1.788 -6.1644E-04 9.9135E-06 -8.9317E-08 4.2613E-10 -8.0638E-13 S4 -0.906 -1.6415E-03 2.1613E-05 -2.4698E-07 1.4899E-09 -4.0313E-12

[0173] See also Fig.16 , is a schematic diagram of a lens according to Example 16 (EX16) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the eighth lens L8 are negative, negative, positive, positive, negative, positive, positive, positive, respectively, and the second lens L2 is an aspheric lens, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0174] Table 1 of Example 16 (EX16):

[0175]

[0176]

[0177] Table 2 of Example 16 (EX16):

[0178] Table 3 of Example 16 (EX16):

[0179]

[0180]

[0181] See also Fig.17 , is a schematic diagram of a lens according to Example 17 (EX17) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, positive, negative, positive, positive, respectively, and the second lens L2 is an aspherical lens, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0182] Table 1 of Example 17 (EX17):

[0183]

[0184]

[0185] Table 2 of Example 17 (EX17):

[0186]

[0187] Table 3 of Example 17 (EX17):

[0188] surface K A^4 B^6 C^8 D^10 E^12 S3 -1.624 -6.3219E-04 9.7030E-06 -8.8244E-08 4.4447E-10 -9.2379E-13 S4 -0.943 -1.4540E-03 1.9662E-05 -2.2170E-07 1.3969E-09 -3.8672E-12

[0189] See also Fig.18 , is a schematic diagram of a lens according to Example 18 (EX18) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the eighth lens L8 are negative, negative, positive, positive, negative, positive, positive, positive, respectively, and the second lens L2 is an aspherical lens, and the sixth lens L6 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0190] Table 1 of Example 18 (EX18):

[0191]

[0192]

[0193] Table 2 of Example 18 (EX18):

[0194]

[0195] Table 3 of Example 18 (EX18):

[0196] surface K A^4 B^6 C^8 D^10 E^12 S3 -1.683 -7.5105E-04 1.3456E-05 -1.2816E-07 6.8320E-10 -1.4753E-12 S4 -0.914 -1.6921E-03 2.5908E-05 -3.1077E-07 2.1017E-09 -6.3850E-12

[0197] See also Fig.19 , is a schematic diagram of a lens according to Example 19 (EX19) of the present invention. In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, positive, positive, positive, respectively, and the second lens L2 is an aspherical lens, and the sixth lens L6 is an inhomogeneous lens with a gradient refractive index and a flat lens. The logic of the remaining element numbers is in accordance with the above embodiments and will not be repeated here.

[0198] Table 1 of Example 19 (EX19):

[0199]

[0200] Table 2 of Example 19 (EX19):

[0201]

[0202]

[0203] Table 3 of Example 19 (EX19):

[0204] surface K A^4 B^6 C^8 D^10 E^12 S3 -1.726 -6.0523E-04 9.6994E-06 -9.3964E-08 4.9906E-10 -1.0827E-12 S4 -0.909 -1.4183E-03 1.8396E-05 -2.1799E-07 1.3956E-09 -3.9245E-12

[0205] See also Fig. 20, is a schematic diagram of a lens according to Example 20 (EX20) of the present invention. The lens 20 has a lens barrel (not shown) having an image magnification side OS and an image reduction side IS. The lens 1 includes a first lens L1, a second lens L2, a third lens L3, an aperture 14, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged from the image magnification side OS to the image reduction side IS. In addition, the aperture 14 toward the image magnification side OS is also called the aperture front, and the aperture 14 toward the image reduction side IS is also called the aperture rear. And behind the seventh lens L7 are the optical path adjustment mechanism 16, the prism 18, the protective lens 10, and the light valve 4 in sequence. The first lens L1, the second lens L2, and the third lens L3 constitute a first lens group 20 with negative refractive power, i.e., the lens group before the aperture 14 (also called the front group); the fourth lens L4, the fifth lens L5, the sixth lens L6, and the seventh lens L7 constitute a second lens group 30 with positive refractive power, i.e., the lens group after the aperture (also called the rear group). In this embodiment, the refractive powers of the first lens L1 to the seventh lens L7 are negative, negative, positive, negative, negative, negative, positive, and positive, respectively, and the first and second lenses (L1, L2) are aspherical lenses, and the fourth lens L4 is an inhomogeneous lens with a gradient refractive index, which is a flat plate structure. The material of the lens closest to the image magnification side OS can be made of glass.

[0206] The difference from the above embodiments is that the change direction of the inhomogeneous material of the gradient refractive index lens L4 of embodiment 20 is not only radial, but also axial. The refractive index calculation formula is as follows: n(r, z) = n 00 +C 10 r 2 +C 20 r 4 +C 30 r 6 +C 40 r 8 +C 01 rz+C 01 rz 2 +C 03 rz 3 +C 04 rz 4 . Where n is the refractive index, r is the radius, 2 =x 2 +y 2 , this formula is in the rectangular coordinate system, with the center of the lens as the origin, the xy coordinates of any point on the lens and the distance from the point to the origin (i.e. the center of the lens) (i.e. the radius r); z is the axial distance, and n(r,z) represents the refractive index of the inhomogeneous lens when the radius r is a certain value and the axial distance is another value; n 00 is the basic refractive index; C i0 (C 10 , C20 , C 30 , C 40 …) and C 0j (C 01 , C 02 , C 03 , C 04 …) represent the correlation coefficients. Table 1 of Example 20 below will reveal the basic parameters of the lens design corresponding to the figure, and Table 2 of Example 20 will reveal the design parameters of the inhomogeneous lens (gradient refractive index lens) corresponding to the figure. Table 2 shows the values ​​of the basic refractive index and the correlation coefficients at different wavelengths of light, where the C-line in the horizontal column is the wavelength of the hydrogen C line (hydrogen red line) light 656.27nm, the d-line is the wavelength of the helium d line (helium yellow line) 587.56nm, the F-line is the wavelength of the hydrogen F line (hydrogen blue line) 486.13nm, and the vertical column is n 00 is the basic refractive index; C 10 , C 20 , C 30 , C 40 , C 01 , C 02 Table 3 of Example 20 discloses the parameters of the aspherical lens.

[0207] Table 1 of Example 20 (EX20):

[0208]

[0209]

[0210] Table 2 of Example 20 (EX20):

[0211]

[0212] Table 3 of Example 20 (EX20):

[0213] surface K A^4 B^6 C^8 D^10 S1 0 9.1099E-04 -5.6717E-06 -6.5778E-08 1.5043E-09 S2 0 -5.7731E-04 6.0829E-05 -1.2373E-06 0.0000E+00 S3 0.642 -6.7225E-03 3.1772E-04 -9.2310E-06 1.0946E-07 S4 -8.650 -2.5884E-03 1.7066E-04 -5.3308E-06 7.2492E-08

[0214] In summary, the present invention can achieve the purpose of reducing the size of the lens through the design of each embodiment. The projection lens provided by the present invention uses a non-homogeneous material to manufacture an achromatic lens, thereby replacing a cemented lens. Since the cemented lens is larger in size (usually thicker), the use of non-homogeneous materials can reduce the size of the lens or lens group with achromatic function. Furthermore, since a single piece of gradient refractive index lens can replace a cemented lens, if the gradient refractive index lens of the present invention is cemented with another lens, such as the present invention, Figure 7The embodiment shown in the figure can achieve the effect of two glued lenses, but the volume is still small, and the purpose of reducing the volume is still achieved overall. Therefore, the present invention using the inhomogeneous material lens has a great contribution to the relevant industry.

[0215] Figure 21 to Figure 24 It is a diagram of optical transfer function (MTF) simulation data of embodiments EX1, EX9, EX10 and EX20 of the present invention. Figure 21 to Figure 24 The figures shown in the simulation data graphs are all within the standard range, which verifies that the projection lenses of various embodiments of the present invention can indeed have the characteristics of good optical imaging quality.

[0216] The parameters in the tables listed in the above specific embodiments are for illustration only and are not intended to limit the present invention. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the definition of the appended claims. In addition, any embodiment or claim of the present invention is not required to achieve all the purposes, advantages or features disclosed in the present invention. The abstract and title are only used to assist in searching patent documents and are not intended to limit the scope of rights of the present invention.

Claims

1. A projection lens, characterized in that: include: A first lens having a refractive power, a second lens having a refractive power, a third lens having a refractive power, a fourth lens having a refractive power, and a fifth lens having a refractive power are arranged in sequence from the magnification side of the projection lens to the reduction side of the projection lens, wherein: At least one of the second lens, the third lens, the fourth lens and the fifth lens is a gradient refractive index lens, and the gradient refractive index lens satisfies 0.6>T / D>0.035, wherein T is the thickness of the gradient refractive index lens at the center of the lens, and D is the maximum outer diameter of the gradient refractive index lens; and An aperture is disposed between the second lens and the reduction side of the projection lens, and the sum of the diopter of the lenses with diopter between the aperture and the reduction side is positive, wherein the number of lenses with diopter of the projection lens is less than 12.

2. A projection lens, characterized in that: include: A first lens having a refractive power, a second lens having a refractive power, a third lens having a refractive power, a fourth lens having a refractive power, and a fifth lens having a refractive power are arranged in sequence from the magnification side of the projection lens to the reduction side of the projection lens; An aperture is disposed between the second lens and the reduction side of the projection lens; and the sum of the diopter powers of the lenses with diopter powers between the aperture and the reduction side is positive; At least one of the second lens, the third lens, the fourth lens and the fifth lens is a material inhomogeneous lens, and the material inhomogeneous lens satisfies 0.6>T / D>0.035, wherein T is the thickness of the material inhomogeneous lens on the optical axis of the projection lens, and D is the maximum outer diameter of the material inhomogeneous lens; and the number of lenses with refractive power of the projection lens is less than 12.

3. The projection lens according to claim 2, wherein: The material inhomogeneous lens is a gradient refractive index lens.

4. The projection lens according to claim 2, wherein: At least one side of the material inhomogeneous lens is a curved surface.

5. The projection lens according to claim 4, wherein: The curved surface of the material inhomogeneous lens is a spherical surface, an aspherical surface, or has a diffractive structure.

6. A projection lens, characterized in that: include: Arranged in order from the magnification side of the projection lens to the reduction side of the projection lens are a first lens having a refractive power, a second lens having a refractive power, a third lens having a refractive power, a fourth lens having a refractive power, and a fifth lens having a refractive power; One of the second lens, the third lens, the fourth lens and the fifth lens is a flat lens with refractive power and a smooth surface without microstructures, and the flat lens meets 0.6>T / D>0.035, T is the thickness of the flat lens, and D is the maximum outer diameter of the flat lens; An aperture is provided between the second lens and the reduction side, and the sum of the diopter powers of the lenses with diopter powers between the aperture and the reduction side is positive; and The number of lenses with diopter of the projection lens is less than 12.

7. The projection lens according to claim 6, wherein: The flat lens with a smooth surface and no microstructure is a gradient refractive index lens.

8. The projection lens according to claim 1, 3 or 7, wherein: The ΔNd value of the gradient refractive index lens meets the following conditions: ΔNd≤Ndmax-Ndmin<0.24, wherein Ndmax is the maximum Nd value of the gradient refractive index lens, and Ndmin is the minimum Nd value of the gradient refractive index lens, and the Nd value is the refractive index of the gradient refractive index lens at the helium d-line.

9. The projection lens according to claim 1, 3 or 7, wherein: The refractive index of the gradient refractive index lens gradually changes in the radial direction.

10. The projection lens according to claim 9, wherein: The surface of the gradient refractive index lens with the gradient direction of the refractive index being radial has a reverse curvature characteristic.

11. The projection lens according to claim 10, wherein: The gradient refractive index lens has a radial gradient direction of refractive index and a surface with a reverse curvature characteristic, and further has an aspherical surface.

12. The projection lens according to claim 9, wherein: The gradient refractive index lens with the gradient direction of the refractive index being radial is a cemented lens.

13. The projection lens according to claim 1, 2 or 6, wherein: Each lens from the magnification side of the projection lens to the aperture is a first lens group, and the first lens group at least includes an aspherical lens.

14. The projection lens according to claim 1, 2, or 6, wherein: Each lens from the reduction side of the projection lens to the aperture is a second lens group, and the sum of the refractive powers of the second lens group is positive.

15. The projection lens according to claim 1, 2, or 6, wherein: The range of the F value of the aperture is: 1.35≤F≤2.

5.

16. The projection lens according to claim 1, 3, or 7, wherein: The refractive index of the gradient refractive index lens gradually changes in the axial direction.

Images