A conoscopic optical system with large field of view and image telecentricity for industrial chromaticity and brightness detection

Abstract

The invention discloses a conoscopic optical system with a large field of view and a telecentric image for industrial chromaticity and brightness detection, which is composed of a front lens group and a rear lens group, a sixth spherical lens is arranged between the front lens group and the rear lens group, the front lens group includes a first spherical lens, a second spherical lens, a third spherical lens, a fourth spherical lens and a fifth cemented spherical lens, and the rear lens group includes a seventh spherical lens, an eighth spherical lens, a ninth spherical lens, a tenth spherical lens, an eleventh spherical lens, a twelfth cemented spherical lens, a thirteenth spherical lens, a fourteenth spherical lens and an image plane. The beneficial effects of the invention are as follows: the viewing angle performance measurement data of the display can be quickly and accurately collected in real time, the chromaticity, brightness and contrast of the light source distribution at multiple angles under a large viewing angle can be measured, the viewing angle data of the complete cone can be collected through a single measurement, and accurate measurement results can be quickly provided, so that the system can become a choice for various R&D projects and online production quality control applications.

Description

Technical Field

[0001] The invention relates to the technical field of optical systems, in particular to a large-field image-side telecentric conoscopic optical system for industrial chromaticity and brightness detection. Background Art

[0002] With the development of science and technology, the industrial revolution is no longer a simple industrial development level. Machine vision can replace traditional manual detection methods, greatly improving the efficiency and effect of industrial manufacturing, thereby greatly improving the product quality in the market. As an important part of machine vision, industrial lenses directly affect the overall performance of the system. For conventional flat panel display devices on the market, the brightness and chromaticity detection methods are mainly through point vertical measurement or area array measurement, but this method can only measure the luminous brightness at a specific angle, and the actual display device has different luminous angles. When the measurement angle changes, it has a great impact on the brightness measurement result, thereby affecting the chromaticity and chromaticity uniformity. Traditional industrial lenses cannot meet the measurement of brightness and chromaticity at multiple angles. Summary of the invention

[0003] The object of the present invention is to provide a large-field-of-view image-space telecentric conoscopic optical system for industrial chromaticity and brightness detection, so as to solve the problems raised in the above-mentioned background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a large-field-of-view image-side telecentric conoscopic optical system for industrial chromaticity and brightness detection, comprising a front lens group and a rear lens group, wherein a sixth spherical lens is arranged between the front lens group and the rear lens group, and the front lens group comprises a first spherical lens, a second spherical lens, a third spherical lens, a fourth spherical lens and a fifth cemented spherical lens; a primary image plane of the front lens group is arranged between the fifth cemented spherical lens and the sixth spherical lens; the rear lens group comprises a seventh spherical lens, an eighth spherical lens, a ninth spherical lens, a tenth spherical lens, an eleventh spherical lens, a twelfth cemented spherical lens, a thirteenth spherical lens, a fourteenth spherical lens and an image plane.

[0005] Preferably, the chief ray of each field of view is between the fourteenth spherical lens and the image plane.

[0006] Preferably, the other end of the first spherical lens away from the second spherical lens is an entrance pupil.

[0007] Preferably, a side of the sixth spherical lens close to the fifth cemented spherical lens is a primary image surface.

[0008] Preferably, the first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, the fifth cemented spherical lens, the seventh spherical lens, the eighth spherical lens, the eleventh spherical lens, the thirteenth spherical lens and the fourteenth spherical lens are all spherical lenses with positive optical power.

[0009] Preferably, the sixth spherical lens, the ninth spherical lens, the tenth spherical lens and the twelfth cemented spherical lens are spherical lenses with negative optical power.

[0010] Preferably, the entrance pupil is placed at the front end of the front group of lenses and is located at the object focal plane position, so as to ensure that the main light incident on the image plane meets the image telecentric optical path requirement.

[0011] Preferably, the first spherical lens, the second spherical lens, the third spherical lens and the fourth spherical lens are curved toward the entrance pupil and are used to collect light at a large angle, and the fifth cemented spherical lens is an achromatic lens, which is beneficial to balancing the axial and lateral chromatic aberrations produced by the first spherical lens, the second spherical lens, the third spherical lens and the fourth spherical lens.

[0012] Preferably, the first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, the fifth cemented spherical lens, the seventh spherical lens, the eighth spherical lens, the ninth spherical lens, the tenth spherical lens, the eleventh spherical lens, the twelfth cemented spherical lens, the thirteenth spherical lens and the fourteenth spherical lens satisfy the following conditional formula:

[0013] -100≤f1 / f≤-1, -0.5≤d1 / f≤-0.01 (1)

[0014] -20≤f2 / f≤-1, -0.5≤d2 / f≤-0.01 (2)

[0015] -20≤f3 / f≤-1, -0.5≤d3 / f≤-0.01 (3)

[0016] -50≤f4 / f≤-1, -0.5≤d4 / f≤-0.01 (4)

[0017] -100≤f5 / f≤-1, -2≤d5 / f≤-0.01 (5)

[0018] 1≤f6 / f≤50,-10≤d6 / f≤-0.02 (6)

[0019] -20≤f7 / f≤-1, -0.5≤d7 / f≤-0.01 (7)

[0020] -20≤f8 / f≤-1, -2≤d8 / f≤-0.02 (8)

[0021] 0.5≤f9 / f≤10, -1≤d9 / f≤-0.01 (9)

[0022] 0.5≤f10 / f≤20, -0.5≤d10 / f≤-0.01 (10)

[0023] -10≤f11 / f≤-1, -1≤d11 / f≤-0.01 (11)

[0024] 0.5≤f12 / f≤20, -1≤d12 / f≤-0.01 (12)

[0025] -20≤f13 / f≤-1, -5≤d13 / f≤-0.02 (13)

[0026] -20≤f14 / f≤-1, -10≤d14 / f≤-0.1 (14),

[0027] Wherein f is the focal length of the combined lens, f1 is the focal length of the first spherical lens, d1 is the interval between the first spherical lens and the second spherical lens; f2 is the focal length of the second spherical lens, d2 is the interval between the second spherical lens and the third spherical lens; f3 is the focal length of the third spherical lens, d3 is the interval between the third spherical lens and the fourth spherical lens; f4 is the focal length of the fourth spherical lens, d4 is the interval between the fourth spherical lens and the fifth cemented spherical lens; f5 is the focal length of the fifth cemented spherical lens, d5 is the interval between the fifth cemented spherical lens and the sixth spherical lens; f6 is the focal length of the sixth spherical lens, d6 is the interval between the sixth spherical lens and the seventh spherical lens; f7 is the focal length of the seventh spherical lens, d7 is the interval between the seventh spherical lens and the eighth spherical lens; f8 is the focal length of the eighth spherical lens, and d8 is the interval between the eighth spherical lens and the ninth spherical lens; f9 is the focal length of the ninth spherical lens, and d9 is the interval between the ninth spherical lens and the tenth spherical lens; f1 is the focal length of the tenth spherical lens, and d1 is the interval between the tenth spherical lens and the eleventh spherical lens; f11 is the focal length of the eleventh spherical lens, and d11 is the interval between the eleventh spherical lens and the twelfth cemented spherical lens; f12 is the focal length of the twelfth cemented spherical lens, and d12 is the interval between the twelfth cemented spherical lens and the thirteenth spherical lens; f13 is the focal length of the thirteenth spherical lens, and d13 is the interval between the thirteenth spherical lens and the fourteenth spherical lens; f14 is the focal length of the fourteenth spherical lens, and d2 is the interval between the fourteenth spherical lens and the image plane.

[0028] Beneficial Effects

[0029] The large-field-of-view image-square telecentric conoscopic optical system for industrial chromaticity and brightness detection provided by the present invention can quickly and accurately collect display viewing angle performance measurement data in real time for flat-panel display manufacturers on the market. It can measure the chromaticity, brightness and contrast of light sources distributed at multiple angles under a large viewing angle. It can collect viewing angle data of a complete cone through a single measurement and quickly provide accurate measurement results, making the system an ideal choice for various R&D projects and online production quality control applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the optical path diagram of the large field of view, image-side telecentric conoscopic objective lens of the present invention;

[0031] Figure 2 This is the principle diagram of the traditional lens chromaticity and brightness measurement;

[0032] Figure 3 The chromaticity and brightness measurement principle diagram of the conoscope lens of the present invention;

[0033] FIG4( a ) is a graph showing the MTF of the conoscope lens when the object distance is infinite in Example 1;

[0034] FIG4( b ) is a graph showing the MTF of the conoscope lens when the object distance is 750 mm in Example 1;

[0035] FIG4( c ) is a graph showing the MTF of the conoscope lens when the object distance is 500 mm in Example 1;

[0036] FIG4( d ) is a graph showing the MTF of the conoscope lens when the object distance is 250 mm in Example 1;

[0037] Figure 5 is the conoscope lens distortion diagram in Example 1;

[0038] Figure 6 is the telecentricity diagram of the conoscope lens in Example 1;

[0039] FIG. 7( a ) is a graph showing the MTF of the conoscope lens when the object distance is infinite in Example 2;

[0040] FIG. 7( b ) is a graph showing the MTF of the conoscope lens when the object distance is 750 mm in Example 2;

[0041] FIG. 7( c ) is a graph showing the MTF of the conoscope lens when the object distance is 500 mm in Example 2;

[0042] FIG. 7( d ) is a graph showing the MTF of the conoscope lens when the object distance is 250 mm in Example 2;

[0043] Figure 8 is the conoscope lens distortion diagram in Example 2;

[0044] Fig. 9 is the telecentricity diagram of the conoscope lens in Example 2;

[0045] FIG. 10( a ) is a graph showing the MTF of the conoscope lens when the object distance is infinite in Example 3;

[0046] FIG. 10( b ) is a graph showing the MTF of the conoscope lens when the object distance is 750 mm in Example 3;

[0047] FIG. 10( c ) is a graph showing the MTF of the conoscope lens when the object distance is 500 mm in Example 3;

[0048] FIG. 10( d ) is a graph showing the MTF of the conoscope lens when the object distance is 250 mm in Example 3;

[0049] Fig.11 : is the conoscope lens distortion diagram in Example 3;

[0050] Fig.12 This is the telecentricity diagram of the conoscope lens in Example 3.

[0051] Reference numerals

[0052] 1-first spherical lens, 2-second spherical lens, 3-third spherical lens, 4-fourth lens, 5-fifth cemented spherical lens, 6-sixth spherical lens, 7-seventh spherical lens, 8-eighth spherical lens, 9-ninth spherical lens, 10-tenth spherical lens, 11-eleventh spherical lens, 12-twelfth cemented spherical lens, 13-thirteenth spherical lens, 14-fourteenth spherical lens, 15-entrance pupil, 16-primary image plane, 17-chief ray of each field of view, 18-image plane. DETAILED DESCRIPTION

[0053] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0054] Example 1

[0055] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0056] A conoscopic optical system with a large field of view and telecentric image for industrial color and brightness detection, such as Figure 1As shown: it is composed of a front lens group and a rear lens group, a sixth spherical lens 6 is arranged between the front lens group and the rear lens group, the front lens group includes a first spherical lens 1, a second spherical lens 2, a third spherical lens 3, a fourth spherical lens 4 and a fifth cemented spherical lens 5; the primary image plane 16 of the front lens group is arranged between the fifth cemented spherical lens and the sixth spherical lens; the rear lens group includes a seventh spherical lens 7, an eighth spherical lens 8, a ninth spherical lens 9, a tenth spherical lens 10, an eleventh spherical lens 11, a twelfth cemented spherical lens 12, a thirteenth spherical lens 13, a fourteenth spherical lens 14 and an image plane 18; the entrance pupil 15 is placed at the front end of the front lens group as the aperture of the conoscopic optical system, and is located at the object focal plane position.

[0057] The preferred embodiment of the above scheme is as follows: the first spherical lens 1, the second spherical lens 2, the third spherical lens 3, and the fourth spherical lens 4 in the front lens group are all positive lenses and are bent toward the entrance pupil to collect light with an angle of 0 to 140 degrees into the front lens group, and the front lens group converges light of different fields of view at the primary image plane 16. Glass with a refractive index greater than 1.6 is selected, which is beneficial to reducing the aperture size of the front lens group and is beneficial to eliminating a part of the field curvature aberration caused by a large angle; the fifth cemented spherical lens 5 is beneficial to eliminating the axial chromatic aberration and magnification chromatic aberration generated by the front lens group; the sixth spherical lens is used as the entire field lens to eliminate part of the field curvature of the front lens group. aberration; the function of the rear group is to ensure that the output light path of the conoscopic optical system is a telecentric light path, and to balance the field curvature aberration produced by the front group; the seventh spherical lens 7 and the eighth spherical lens 7 are used to eliminate the following related to the field of view: coma, astigmatism, and field curvature; the ninth spherical lens 9 and the tenth spherical lens 10 are negative lenses, which are used to balance the spherical aberration, astigmatism, and field curvature of the entire conoscopic optical system; the twelfth cemented spherical lens 12 is used to balance the spherical aberration, axial chromatic aberration, and chromatic aberration of magnification; the thirteenth spherical lens 13 and the fourteenth spherical lens 14 are used to eliminate the spherical aberration, astigmatism, and change the direction of the main light ray 17 of each field of view, which is conducive to the realization of the image side telecentric light path.

[0058] Since the conoscopic optical system has a reasonable focal power distribution, it can effectively suppress aberrations and design a large field of view, image-side telecentric conoscopic optical objective. FOV is the imaging field of view, and CRA is the telecentricity (the parallelism between the main light and the optical axis).

[0059] 120 degrees ≤ FOV ≤ 140 degrees.

[0060] CRA≤0.05 degrees.

[0061] The aperture of a traditional lens is usually located inside the lens. Figure 2 As shown, when the object to be measured has a field stop, the edge field of view is easily blocked, so that imaging in the direction of a large field of view cannot be obtained; Figure 3Based on the imaging principle of the conoscopic optical system, this lens is designed to simulate the size, position and field of view of the human eye. Unlike other lenses where the aperture is located inside the lens, since the aperture is located in front of the lens, the connected imaging system can capture the full field of view (FOV) of the display without any lens hardware obstruction.

[0062] The lens entrance pupil diameter D = 3.6mm, the field of view is 120°, and focusing is achieved by moving the relative distance between the front group and the rear group. The focusing range is 250mm~∞. The design parameters of the optical system are shown in Table 1, the focusing distances of the front and rear groups at different object distances are shown in Table 2, and the MTF curves of different object distances under the full field of view are shown in Figures 4(a), 4(b), 4(c), and 4(d), respectively. The MTF values ​​are all 100lp / mm≥0.3, with high resolution; the distortion is as follows Figure 5 As shown, its value is less than 35%, which is within the acceptable range; the telecentricity of this conoscope lens is as follows Figure 6 As shown, its telecentricity CRA≤0.05.

[0063] The 3.6mm entrance pupil matches the size of the human eye’s entrance pupil, which enables the measurement system to measure the display under the same conditions as an observer would see it.

[0064] Table 1. Design parameters of conoscopic optical system with 120° field of view

[0065]

[0066]

[0067] Table 2. Focusing distances of front and rear groups at different object distances for a 120° field of view conoscopic optical system

[0068] Object distance (0stop) Thickness (14 sides) Infinity 49.710946 1000 50.118181 500 50.523156 250 51.336590

[0069] Embodiment 2:

[0070] The lens entrance pupil diameter D = 3.6mm, the field of view is 130°, and the focusing is achieved by moving the relative distance between the front group and the rear group. The focusing range is 250mm~∞. The design parameters of the optical system are shown in Table 3, the focusing distances of the front and rear groups at different object distances are shown in Table 4, and the MTF curves of different object distances under the full field of view are shown in Figures 7(a), 7(b), 7(c), and 7(d), respectively. The MTF values ​​are all 100lp / mm≥0.3, with high resolution; the distortion is as follows Figure 8 As shown, its value is less than 43%, which is within the acceptable range; the telecentricity of this conoscope lens is as follows Fig. 9 As shown, its telecentricity CRA≤0.05.

[0071] Table 3. Design parameters of conoscopic optical system with 130° field of view

[0072]

[0073]

[0074] Table 4. Focusing distances of front and rear groups at different object distances for a 130° field of view conoscopic optical system

[0075] Object distance (0stop) Thickness (14 sides) Infinity 50.200981 1000 50.53356 500 50.86634 250 51.53286

[0076] Embodiment 3:

[0077] The lens entrance pupil diameter D = 3.6mm, the field of view is 140°, and the focusing is achieved by moving the relative distance between the front group and the rear group. The focusing range is 250mm~∞. The design parameters of the optical system are shown in Table 5, the focusing distances of the front and rear groups at different object distances are shown in Table 6, and the MTF curves of different object distances under the full field of view are shown in Figures 10(a), 10(b), 10(c), and 10(d), respectively. The MTF values ​​are all 100lp / mm≥0.15, with high resolution; the distortion is as follows Fig.11 As shown, its value is less than 50%, which is within the acceptable range; the telecentricity of this conoscope lens is as follows Fig.12 As shown, its telecentricity CRA≤0.05.

[0078] Table 5. Design parameters of conoscopic optical system with 140° field of view

[0079]

[0080]

[0081] Table 6. Focusing distances of front and rear groups at different object distances for a 140° field of view conoscopic optical system

[0082] Object distance (0stop) Thickness (14 sides) Infinity 50.183452 1000 50.460141 500 50.734773 250 51.288693

[0083] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the invention content within the protection scope of the present invention.

Claims

1. A conoscopic optical system with a large field of view and image-side telecentricity for industrial chromaticity and brightness detection, consisting of a front lens group and a rear lens group, characterized in that: A sixth spherical lens is disposed between the front lens group and the rear lens group; the front lens group is composed of a first spherical lens, a second spherical lens, a third spherical lens, a fourth spherical lens and a fifth cemented spherical lens; a primary image plane of the front lens group is disposed between the fifth cemented spherical lens and the sixth spherical lens; the rear lens group is composed of a seventh spherical lens, an eighth spherical lens, a ninth spherical lens, a tenth spherical lens, an eleventh spherical lens, a twelfth cemented spherical lens, a thirteenth spherical lens, a fourteenth spherical lens and an image plane; The first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, the fifth cemented spherical lens, the seventh spherical lens, the eighth spherical lens, the eleventh spherical lens, the thirteenth spherical lens and the fourteenth spherical lens are all spherical lenses with positive optical power; The sixth spherical lens, the ninth spherical lens, the tenth spherical lens and the twelfth cemented spherical lens are spherical lenses with negative optical power; The first spherical lens, the second spherical lens, the third spherical lens, and the fourth spherical lens are curved toward the entrance pupil and are used to collect light at a large angle. The fifth cemented spherical lens is an achromatic lens, which is conducive to balancing the axial and lateral chromatic aberrations generated by the first spherical lens, the second spherical lens, the third spherical lens, and the fourth spherical lens; The first spherical lens, the second spherical lens, the third spherical lens, the fourth spherical lens, and the fifth cemented spherical lens satisfy the following conditional formula: -100≤f1 / f≤-1, -0.5≤d1 / f≤-0.01 (1) -20≤f2 / f≤-1, -0.5≤d2 / f≤-0.01 (2) -20≤f3 / f≤-1, -0.5≤d3 / f≤-0.01 (3) -50≤f4 / f≤-1, -0.5≤d4 / f≤-0.01 (4) -100≤f5 / f≤-1, -2≤d5 / f≤-0.01 (5) Wherein, f is the focal length of the conoscopic optical system, f1 is the focal length of the first spherical lens, d1 is the interval between the first spherical lens and the second spherical lens; f2 is the focal length of the second spherical lens, d2 is the interval between the second spherical lens and the third spherical lens; f3 is the focal length of the third spherical lens, d3 is the interval between the third spherical lens and the fourth spherical lens; f4 is the focal length of the fourth spherical lens, d4 is the interval between the fourth spherical lens and the fifth cemented spherical lens; f5 is the focal length of the fifth cemented spherical lens, d5 is the interval between the fifth cemented spherical lens and the sixth spherical lens.

2. The large-field telecentric conoscopic optical system for industrial chromaticity and brightness detection according to claim 1, characterized in that: The main light of each field of view is between the fourteenth spherical lens and the image plane.

3. The large-field telecentric conoscopic optical system for industrial chromaticity and brightness detection according to claim 1, characterized in that: The other end of the first spherical lens away from the second spherical lens is an entrance pupil.

4. The large-field image-space telecentric conoscopic optical system for industrial chromaticity and brightness detection according to claim 1, characterized in that: A side of the sixth spherical lens close to the fifth cemented spherical lens is a primary image surface.

5. The large-field image-space telecentric conoscopic optical system for industrial chromaticity and brightness detection according to claim 3, characterized in that: The entrance pupil is placed at the front end of the front lens group and is located at the object focal plane position, so as to ensure that the main light incident on the image plane meets the image telecentric optical path requirement.

6. The large-field image-space telecentric conoscopic optical system for industrial chromaticity and brightness detection according to claim 1, characterized in that: The seventh spherical lens, the eighth spherical lens, the ninth spherical lens, the tenth spherical lens, the eleventh spherical lens, the twelfth cemented spherical lens, the thirteenth spherical lens and the fourteenth spherical lens satisfy the following conditional formula: 1≤f6 / f≤50,-10≤d6 / f≤-0.02 (6) -20≤f7 / f≤-1, -0.5≤d7 / f≤-0.01 (7) -20≤f8 / f≤-1, -2≤d8 / f≤-0.02 (8) 0.5≤f9 / f≤10, -1≤d9 / f≤-0.01 (9) 0.5≤f10 / f≤20, -0.5≤d10 / f≤-0.01 (10) -10≤f11 / f≤-1, -1≤d11 / f≤-0.01 (11) 0.5≤f12 / f≤20, -1≤d12 / f≤-0.01 (12) -20≤f13 / f≤-1, -5≤d13 / f≤-0.02 (13) -20≤f14 / f≤-1, -10≤d14 / f≤-0.1 (14), Wherein f6 is the focal length of the sixth spherical lens, d6 is the distance between the sixth spherical lens and the seventh spherical lens; f7 is the focal length of the seventh spherical lens, d7 is the distance between the seventh spherical lens and the eighth spherical lens; f8 is the focal length of the eighth spherical lens, d8 is the distance between the eighth spherical lens and the ninth spherical lens; f9 is the focal length of the ninth spherical lens, d9 is the distance between the ninth spherical lens and the tenth spherical lens; f10 is the focal length of the tenth spherical lens, d10 is the distance between the tenth spherical lens and the ninth spherical lens; The image plane is spaced from the first spherical lens to the second spherical lens; f11 is the focal length of the eleventh spherical lens, and d11 is the distance between the eleventh spherical lens and the twelfth cemented spherical lens; f12 is the focal length of the twelfth cemented spherical lens, and d12 is the distance between the twelfth cemented spherical lens and the thirteenth spherical lens; f13 is the focal length of the thirteenth spherical lens, and d13 is the distance between the thirteenth spherical lens and the fourteenth spherical lens; f14 is the focal length of the fourteenth spherical lens, and d14 is the distance between the fourteenth spherical lens and the image plane.

Images