A SAM projection lens and projection device

Abstract

This application relates to the field of SAM projection lens technology, providing a SAM projection lens and projection device. The SAM projection lens includes a rear group and a front group arranged sequentially from the object side to the image side along the optical axis. The rear group includes a positive power lens, an aperture stop, and three cemented doublets. The cemented surfaces of the three cemented doublets partially bulge towards the aperture stop and partially bulge away from it. The front group includes a negative power lens and two cemented doublets, one of which has a negative power. The SAM projection lens and projection device provided in this application can guarantee brightness, achieve a large atmospheric back focus, and provide high image quality at a low cost.

Description

Technical Field

[0001] This application belongs to the field of SAM projection lens technology, and particularly relates to a SAM projection lens and projection device. Background Technology

[0002] SAM projection lenses can achieve clear image quality on tilted projection surfaces and are widely used in circuit board defect detection, head-up displays (HUDs), and other fields. However, existing SAM projection lenses achieve imaging by simultaneously tilting both the object plane and the projection plane (image plane), requiring the aberrations of the projection plane to meet a certain linear distribution in the image space. This places strict requirements on aberration correction. Furthermore, to ensure brightness, the object side needs to be kept as far telecentric as possible, and the lens aperture (F#) needs to be controlled around F2.0, which further increases the difficulty of correcting spherical aberration, coma, and astigmatism. Additionally, to avoid interference between illumination and imaging rays and to eliminate prisms to reduce costs, the distance between the display chip and the lens needs to be increased, leading to increased back focal length and a larger incident beam diameter at the lens, further exacerbating aperture aberration. Summary of the Invention

[0003] In view of this, the present application provides a Sham projection lens and projection device, which aims to solve the problem that existing Sham projection lenses have strict requirements for aberration correction. Under the condition of ensuring brightness and having a large atmospheric back focus, it is difficult to correct related aberrations such as spherical aberration, coma and astigmatism, and the aperture aberration is large.

[0004] A first aspect of this application provides a Sham projection lens, including a rear group and a front group arranged sequentially from the object side to the image side along the optical axis;

[0005] The rear group includes a positive power lens, an aperture stop, and three cemented doublet lenses. The cemented surfaces of the three cemented doublet lenses partially bulge towards the aperture stop and partially bulge away from the aperture stop.

[0006] The front group includes a negative power lens and two cemented doublets, one of which has a negative power.

[0007] In one embodiment, the rear group includes a first positive power lens, a first cemented doublet lens, a second cemented doublet lens, an aperture stop, and a third cemented doublet lens;

[0008] The first positive power lens is biconvex.

[0009] The first doublet lens is biconvex, with the cemented surface convex toward the aperture and having a positive optical power.

[0010] In one embodiment, the cemented surface of the second cemented doublet bulges away from the aperture stop and has a negative optical power, while the cemented surface of the third cemented doublet bulges towards the aperture stop and has a positive optical power.

[0011] In one embodiment, the refractive index of the first positive power lens is lower than or equal to a first refractive index, and the Abbe number is higher than or equal to a first Abbe number;

[0012] The refractive index of the positive power lens in the first cemented doublet is lower than or equal to the first refractive index, and the Abbe number is higher than or equal to the first Abbe number. The refractive index of the negative power lens in the first cemented doublet is higher than or equal to the second refractive index, and the Abbe number is lower than or equal to the second Abbe number.

[0013] The refractive index of the negative power lens in the first group is lower than or equal to the first refractive index, and the Abbe number is higher than or equal to the first Abbe number.

[0014] Wherein, the first refractive index is lower than the second refractive index, and the first Abbe number is higher than the second Abbe number.

[0015] In one embodiment, the first refractive index is equal to 1.65, and the second refractive index is equal to 1.83;

[0016] The first Abbe number is 60, and the second Abbe number is 32.

[0017] In one embodiment, the first cemented doublet lens includes a second negative power lens and a third positive power lens;

[0018] The second cemented doublet lens includes a fourth positive power lens and a fifth negative power lens;

[0019] The third cemented doublet lens includes a sixth positive power lens and a seventh negative power lens.

[0020] In one embodiment, the front group includes an eighth negative power lens, a fourth cemented doublet lens, and a fifth cemented doublet lens;

[0021] The fourth cemented doublet lens is meniscus-shaped and has a negative optical power.

[0022] In one embodiment, the optical power of the fifth cemented doublet lens is positive.

[0023] In one embodiment, the fourth cemented doublet lens includes a ninth negative power lens and a tenth positive power lens;

[0024] The fifth cemented doublet lens includes an eleventh negative power lens and a twelfth positive power lens.

[0025] A second aspect of this application provides a head-up display device, including the Sham projection lens provided in the first aspect.

[0026] In one embodiment, the projection device is a head-up display device or a circuit board defect detection device.

[0027] In the Sham projection lens provided in the first aspect of this application, the rear group uses vignetting to intercept beams with severe off-axis field-of-view aberrations, reducing the difficulty of correcting coma and astigmatism in the off-axis field of view. It uses three cemented doublets to correct chromatic aberration, coma, and astigmatism, while a positive optical power lens takes on the main optical power and corrects spherical aberration. The negative optical power lens in the front group, together with the negative optical power cemented doublet, takes on the negative optical power of the front group, reducing the generation of higher-order aberrations. Furthermore, both the front and rear groups have cemented doublets, which can achieve distributed correction of chromatic aberration.

[0028] The projection device provided in the second aspect of the embodiments of this application, by employing the SAM projection lens provided in the first aspect, can ensure brightness, obtain a large atmospheric back focus, and achieve high imaging quality and low cost. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of a Sham projection lens provided in one embodiment of this application;

[0031] Figure 2 This is a schematic diagram of the structure of the rear assembly provided in an embodiment of this application;

[0032] Figure 3 This is a schematic diagram of the front assembly provided in an embodiment of this application;

[0033] Figure 4 This is a schematic diagram of the structure of a Sham projection lens provided in another embodiment of this application;

[0034] Figure 5 This is a schematic diagram of a Sham projection lens and its projection surface provided in an embodiment of this application;

[0035] Figure 6 This is a schematic diagram of the modulation transfer function at the display chip provided in an embodiment of this application;

[0036] Icon labels:

[0037] 100 - Projection lens;

[0038] 101 - Display chip;

[0039] 102 - Optical compensation plate;

[0040] 103-Polarizer;

[0041] 110 - Rear group, 111 - First positive power lens, 112 - Second negative power lens, 113 - Third positive power lens, 114 - Fourth positive power lens, 115 - Fifth negative power lens, 116 - Aperture stop, 117 - Sixth positive power lens, 118 - Seventh negative power lens;

[0042] 120 - Front group, 121 - Eighth negative power lens, 122 - Ninth negative power lens, 123 - Tenth positive power lens, 124 - Eleventh negative power lens, 125 - Twelfth positive power lens. Detailed Implementation

[0043] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present application.

[0044] The term "comprising," and any variations thereof, in the specification, claims, and accompanying drawings of this application are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that comprises a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such processes, methods, products, or apparatus. Furthermore, the terms "first," "second," and "third," etc., are used to distinguish different objects, not to describe a specific order.

[0045] like Figure 1 As shown, this embodiment provides a Sham projection lens 100, including a rear group 110 and a front group 120 arranged sequentially from the object side to the image side along the optical axis.

[0046] The rear group 110 includes a positive power lens, an aperture stop 116, and three cemented doublet lenses. The cemented surfaces of the three cemented doublet lenses protrude towards the aperture stop 116 and protrude away from the aperture stop 116.

[0047] The front group 120 includes a negative power lens and two cemented doublets, one of which has a negative power.

[0048] In application, the rear group 110 controls the aperture of the positive power lens to block light rays at the aperture edge, and uses vignetting to block light rays with large aberrations, thereby reducing the difficulty of correcting coma and astigmatism in the off-axis field of view. Three cemented doublets are used to correct chromatic aberration, coma, and astigmatism, while the positive power lens handles the main optical power and corrects spherical aberration. The negative power lens of the front group 120, together with the negative power cemented doublet, handles the negative optical power of the front group 120, reducing the generation of higher-order aberrations; and both the front group 120 and the rear group 110 have cemented doublets, enabling distributed correction of chromatic aberration. The aperture stop 116 is used to limit the incident angle and luminous flux of the beam, eliminate stray light, and correct off-axis aberrations.

[0049] like Figure 2 As shown, in one embodiment, the rear group 110 includes a first positive power lens 111, a first cemented doublet lens, a second cemented doublet lens, an aperture stop 116, and a third cemented doublet lens.

[0050] Among them, the first positive power lens 111 is biconvex;

[0051] The first cemented doublet is biconvex, with the cemented surface convex toward the aperture stop 116 and having a positive optical power.

[0052] In application, both the first positive optical power lens 111 and the first cemented doublet are biconvex, facilitating the provision of positive optical power. By sharing the optical power, aperture aberrations, primarily spherical aberration, are reduced at their source, contributing to improved image quality. The first cemented doublet provides weak positive optical power, and its cemented surface convexes towards the aperture stop 116, conforming to the angle of light incidence and aiding in smooth light transition to avoid the generation of advanced aberrations.

[0053] In one embodiment, the optical power of the second cemented doublet is negative, and the optical power of the third cemented doublet is positive.

[0054] In application, the second cemented doublet has a negative weak optical power, forming a positive-negative optical power combination with the first and third cemented doublets on the left and right sides, which have positive optical power, to correct coma and astigmatism. The third cemented doublet has a positive optical power, which can converge the beam from the rear group 110, allowing it to be incident on the negative optical power lens of the front group 120 with a smaller beam aperture, which is beneficial for field curvature correction. The cementing surface of the second cemented doublet bulges away from the aperture stop 116, while the cementing surface of the third cemented doublet bulges towards the aperture stop 116, providing high compatibility. Both are located on opposite sides of the aperture stop 116, allowing for individual modulation of the upper or lower edge light rays of the aperture. By changing the radius of curvature of the cementing surface, the incident angle can be indirectly changed, controlling the degree of modulation and obtaining correction effects for coma and astigmatism of different degrees and directions.

[0055] In one embodiment, the refractive index (Nd) of the first positive power lens 111 is lower than or equal to the first refractive index, and the Abbe number (Vd) is higher than or equal to the first Abbe number.

[0056] In the first cemented doublet, the refractive index of the positive power lens is lower than or equal to the first refractive index, and the Abbe number is higher than or equal to the first Abbe number; in the first cemented doublet, the refractive index of the negative power lens is higher than or equal to the second refractive index, and the Abbe number is lower than or equal to the second Abbe number.

[0057] The refractive index of the negative power lens in the front group 120 is lower than or equal to the first refractive index, and the Abbe number is higher than or equal to the first Abbe number;

[0058] Among them, the first refractive index is lower than the second refractive index, and the first Abbe number is higher than the second Abbe number.

[0059] In application, the first positive power lens 111, the positive power lens in the first cemented doublet, and the negative power lens in the front group 120 have relatively low refractive indices, while the negative power lens in the first cemented doublet has a relatively high refractive index.

[0060] The first positive power lens 111, the positive power lens in the first cemented doublet, and the negative power lens in the front group 120 have relatively high Abbe numbers, while the negative power lens in the first cemented doublet has a relatively low Abbe number.

[0061] The first refractive index, the second refractive index, the first Abbe number, and the second Abbe number can be set according to actual needs, as long as the relative magnitudes of the above are satisfied.

[0062] In one embodiment, the first refractive index is equal to 1.65 and the second refractive index is equal to 1.83;

[0063] The first Abbe number is 60, and the second Abbe number is 32.

[0064] In application, the first positive power lens 111 is made of a material with low refractive index (≤1.65) and high Abbe number (≥60), which, while bearing the main positive power, can minimize the occurrence of chromatic aberration. The positive power lens of the first cemented doublet is made of a material with low refractive index (≤1.65) and high Abbe number (≥60), while the negative power lens of the first cemented doublet is made of a material with high refractive index (≥1.83) and low Abbe number (≤32), which is beneficial for chromatic aberration correction.

[0065] In application, the negative power lens of the front group 120 is made of a low refractive index (≤1.65) and high Abbe number (≥60) material. Since the beam aperture is the smallest at this negative power lens, it can form a structure with the third cemented doublet lens of the rear group 110 to correct field curvature by separating positive and negative power. The use of a low refractive index material for this negative power lens is beneficial for field curvature correction. On the other hand, the low refractive index causes an increase in the curvature of the left and right surfaces, and the light rays produce a larger angle at this negative power lens, resulting in primary and secondary aberrations. By using a low refractive index material, a smaller negative power loss is provided for the entire Sham projection lens 100, contributing a larger aberration of opposite sign required by the Sham projection lens 100.

[0066] like Figure 2 As shown, in one embodiment, the first cemented doublet lens includes a second negative power lens 112 and a third positive power lens 113;

[0067] The second cemented doublet lens includes a fourth positive power lens 114 and a fifth negative power lens 115;

[0068] The third cemented doublet lens includes a sixth positive power lens 117 and a seventh negative power lens 118.

[0069] In applications, the two lenses in the first, second, and third cemented doublet lenses can be bonded together using adhesive methods, and can also have suitable air gaps. Each positive and negative power lens can also be split into two positive and negative power lenses with equal functions. The specific configuration of each lens is not limited in the embodiments of this application.

[0070] like Figure 3 As shown, in one embodiment, the front group 120 includes an eighth negative power lens 121, a fourth cemented doublet lens, and a fifth cemented doublet lens;

[0071] Among them, the eighth negative power lens 121 is biconcave;

[0072] The fourth cemented doublet is meniscus-shaped and has a negative optical power.

[0073] In application, the fourth cemented doublet lens of the front group 120 has a thick crescent shape. On the one hand, it causes the separation of positive and negative optical power, which optimizes the field curvature. On the other hand, it conforms to the incident angle of light, which realizes the smooth transition of the beam and reduces the generation of advanced aberrations.

[0074] In one embodiment, the optical power of the fifth cemented doublet lens is positive.

[0075] In application, the fifth cemented doublet of the front group 120 has a positive optical power and is paired with the fourth cemented doublet, which has a negative optical power. The distortion is corrected by canceling out the positive and negative aberrations.

[0076] like Figure 3 As shown, in one embodiment, the fourth cemented doublet lens includes a ninth negative power lens 122 and a tenth positive power lens 123;

[0077] The fifth cemented doublet lens includes the eleventh negative power lens 124 and the twelfth positive power lens 125.

[0078] In applications, the two lenses in the fourth and fifth cemented doublet lenses can be bonded together using adhesive methods, and can also have suitable air gaps. Each positive and negative power lens can also be split into two positive and negative power lenses with equal functions. The specific configuration of each lens is not limited in the embodiments of this application.

[0079] In application, the first to fifth cemented doublets in the entire Sham projection lens 100 are essentially combinations of positive and negative power lenses. This combination is distributed throughout the front group 120 and rear group 110 of the entire Sham projection lens 100. The aperture aberration and field aberration are corrected by positive and negative cancellation, so that the aberrations of the entire Sham projection lens 100 can be suppressed in their respective local areas, resulting in a smaller total aberration.

[0080] like Figure 1 , Figure 2 or Figure 3 As shown, in one embodiment, all lenses in the projection lens 100 are spherical lenses;

[0081] Arranged sequentially from the object side to the image side along the optical axis, the rear group 110 includes: a first positive power lens 111, a second negative power lens 112, a third positive power lens 113, a fourth positive power lens 114, a fifth negative power lens 115, an aperture stop 116, a sixth positive power lens 117, and a seventh negative power lens 118.

[0082] The front group 120 includes: an eighth negative power lens 121, a ninth negative power lens 122, a tenth positive power lens 123, an eleventh negative power lens 124, and a twelfth positive power lens 125.

[0083] In applications, by correcting aberrations in different regions, aspherical lenses can be avoided, reducing mold costs while achieving high resolution.

[0084] like Figure 6 As shown, in one embodiment, the Sham projection lens 100 further includes a display chip 101, an optical compensation sheet 102, and a polarizer 103 located on the object side and arranged in sequence.

[0085] In applications, the display chip 101 can be selected based on Digital Light Processing (DLP), Liquid Crystal on Silicon (LCOS), or Liquid Crystal Display (LCD) technologies, depending on actual needs. The optical compensation plate 102 may include at least one of a quarter-wave plate and a polarization beam splitter (PBS). The SAM projection lens 100 may also include a protective glass, and the display chip 101 and the protective glass can be integrated into a single unit.

[0086] like Figure 4 or Figure 5 As shown, in one embodiment, the display chip 101 is implemented based on LCOS technology and has a size of 0.37 inches (i.e., image plane size). The tilt angle of the entire projection plane of the Sham projection lens 100 (i.e., the object plane where the display plane of the display chip 101 is located) relative to the vertical plane (i.e., the plane perpendicular to the optical axis) can be set according to actual needs (e.g., 15°), and the aperture F# = 2.0. The type, radius of curvature, thickness, and glass material of the Sham projection lens 100 from the object plane to the image plane are shown in Table 1 below:

[0087] Table 1

[0088]

[0089]

[0090] like Figure 6 As shown, an exemplary schematic diagram of the modulation transfer function (MTF) at display chip 101 is illustrated; where the MTF observation line pair is 9 lp / mm, the horizontal axis represents the spatial frequency in cycles per millimeter (cycles / mm), and the vertical axis represents the MTF value.

[0091] In applications, MTF represents the overall resolving power of an optical system. The MTF value is used to evaluate the image quality of a lens, ranging from 0 to 1. A higher and straighter vertical axis on the MTF curve indicates better image quality, stronger ability to reproduce realistic images, better overlap of curves across different fields of view, and better consistency of image quality. Figure 6 It can be seen that in the visible light band, when the spatial frequency is 9lp / mm, the MTF of the entire field of view is ≥0.4, indicating good imaging quality.

[0092] This embodiment also provides a projection device, including the Sham projection lens 100 in any of the above embodiments.

[0093] In applications, the projection device can be a HUD device or a projector used in circuit board defect detection. By using the SAM projection lens 100, brightness, a large atmospheric back focus, high image quality, and low cost can be guaranteed. When the projection device is used in HUD device circuit board or defect detection, the display chip 101 in the SAM projection lens 100 can be implemented based on LCOS technology. Since an aspherical lens is not used, the structure of the SAM projection lens 100 is simplified, and the cost of the SAM projection lens 100 is reduced.

[0094] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A Sham projection lens, characterized in that, It consists of a total of 12 lenses, arranged sequentially from the object side to the image side along the optical axis to form the rear group and the front group; The rear group includes a first positive power lens, a first cemented doublet, a second cemented doublet, an aperture stop, and a third cemented doublet arranged sequentially from the object side to the image side along the optical axis. The first cemented doublet includes a second negative power lens and a third positive power lens. The second cemented doublet includes a fourth positive power lens and a fifth negative power lens. The third cemented doublet includes a sixth positive power lens and a seventh negative power lens. The front group includes an eighth negative power lens, a fourth cemented doublet lens, and a fifth cemented doublet lens arranged sequentially from the object side to the image side along the optical axis. The fourth cemented doublet lens includes a ninth negative power lens and a tenth positive power lens, and the fifth cemented doublet lens includes an eleventh negative power lens and a twelfth positive power lens. The first positive power lens is biconvex. The first doublet lens is biconvex, with the cemented surface convex toward the aperture and having a positive optical power; The cemented surface of the second cemented doublet bulges away from the aperture stop and has a negative optical power, while the cemented surface of the third cemented doublet bulges towards the aperture stop and has a positive optical power. The fourth cemented doublet lens is meniscus-shaped and has a negative optical power. The optical power of the fifth cemented doublet lens is positive; The following table shows the type, radius of curvature, thickness, and glass material of the Sham projection lens from the object plane to the image plane: 。 2. A projection device, characterized in that, Including the Sham projection lens as described in claim 1.

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