CN115980972A - Close-up lens for detecting image quality of mid-focus video monitoring camera lens and detection method - Google Patents
Close-up lens for detecting image quality of mid-focus video monitoring camera lens and detection method Download PDFInfo
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- CN115980972A CN115980972A CN202211701767.8A CN202211701767A CN115980972A CN 115980972 A CN115980972 A CN 115980972A CN 202211701767 A CN202211701767 A CN 202211701767A CN 115980972 A CN115980972 A CN 115980972A
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- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0055—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element
- G02B13/006—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras employing a special optical element at least one element being a compound optical element, e.g. cemented elements
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Abstract
The application of the divisional scheme relates to a close-up lens for detecting the image quality of a medium-focus video monitoring camera lens and a detection method, wherein the close-up lens for detecting the medium-focus video monitoring camera lens comprises a close-up lens and a close-joint gluing combination of a third lens and a fourth lens, the close-up lens and the detection method can meet the detection of the image quality of the video monitoring camera lens within the focal length range of 8-20mm, the addition of the close-up lens does not influence the corrected imaging quality of the video monitoring camera lens, and the close-up lens can prolong the close object distance and shorten the far object distance, thereby realizing the miniaturization of the detection equipment.
Description
The invention relates to a close-up lens for assisting image quality detection of a video monitoring camera lens and a divisional application of a detection method, wherein the patent application date is 2017, 8, 10 and the patent application number is 201710680696.0.
Technical Field
The invention relates to the field of optics, in particular to a close-up lens for detecting the image quality of a mid-focus video monitoring camera lens and a detection method.
Background
With the arrival of the video shooting technology entering the era of high-definition image quality over million total pixels, the imaging quality of the camera lens serving as a matched key component is also required to be greatly improved (the current enterprise requirement reaches about 500-1000 ten thousand). Because of its high throughput, how to effectively detect the imaging quality of such lenses has become a focus of attention in the optical world at home and abroad. At present, the method has the industrial detection standard, can adapt to different focal length requirements, is intuitive and cost-effective, and is more applicable by adopting a resolution test card method. Particularly, the lens is directly combined with a camera, and the imaging effect of the lens in a camera system can be better reflected. By replacing the color test card, the effect of visually detecting the color restoration of the lens, which is difficult to achieve by other methods, can be achieved. But the difficulty is how to really reflect the imaging effect on the practical distance when detecting the ultra-wide-angle short-focus lens; when detecting the telephoto lens, how to solve the problems of effective illumination, manufacture of a large-layout resolution test card, miniaturization of equipment and the like.
Disclosure of Invention
The invention aims to overcome the defects and provides a close-up lens and a detection method for detecting the image quality of a medium-focus video surveillance camera lens, the close-up lens and the detection method can meet the detection of the image quality of the video surveillance camera lens within the focal length range of 8-20mm, the addition of the close-up lens does not influence the corrected imaging quality of the video surveillance camera lens, and the close-up lens can lengthen the close object distance and shorten the far object distance, thereby realizing the miniaturization of detection equipment.
The invention is realized by the following steps:
scheme (I):
the utility model provides a close-up lens that is used for well focus video surveillance camera lens image quality to detect which characterized in that: the optical elements forming each close-focus lens must meet the following conditions:
0.01＜Pcd12-Pcd11＜0.02；20＜R12/R11＜26‥‥‥①
0.28≦|Φ1/R11-Φ1/R12|‥‥‥②
1.50＜n11＜1.54；60＜ν11＜65‥‥‥③
1.60＜n12＜1.626；35＜ν12＜38‥‥‥④
0.008＜Pcd22-Pcd21＜0.012；4＜|R22/R21|＜6‥‥‥⑤
0.4≦|Φ2/R21-Φ2/R22|‥‥‥⑥
1.50＜n21＜1.54；60＜ν21＜65‥‥‥⑦
1.60＜n22＜1.63；56＜ν22＜61‥‥‥⑧
0.001＜Pcd32-Pcd31＜0.006；8＜|R32/R31|＜12‥‥‥⑨
0.4≦|Φ3/R31-Φ3/R32|‥‥‥⑩
1.57＜n31＜1.1.63；55＜ν31＜59‥‥‥
1.60＜n32＜1.63；56＜ν32＜61‥‥‥
wherein, pcd11, pcd12, pcd21, pcd22, pcd31, pcd32 are relative dispersion coefficients of the first to sixth lenses respectively; r11, R12, R13, R21, R22, R23, R31, R32, and R33 are radii of the respective surfaces of the first to sixth lenses; phi 1 to phi 3 are respectively the apertures of a first close-up lens to a third close-up lens; n11, n12, n21, n22, n31, n32 are refractive indices of the first to sixth lenses, respectively; ν 11, ν 12, ν 21, ν 22, ν 31, and ν 32 are abbe coefficients of the first to sixth lenses, respectively.
Preferably, the first lens is a convex-concave positive lens, and the second lens is a convex-concave negative lens; the third lens is a convex-concave positive lens, and the fourth lens is a convex-concave negative lens; the fifth lens is a concave-convex positive lens, and the sixth lens is a concave-convex negative lens.
Preferably, the focal length range of the short-focus video surveillance camera lens is 2.5-8mm, the focal length range of the middle-focus video surveillance camera lens is 8-20mm, and the focal length range of the long Jiao Shipin surveillance camera lens is 20-75 mm.
Preferably, the first lens and the third lens are made of H-K9L, the second lens and the fourth lens are made of H-F4, the fifth lens is made of H-ZK3, and the sixth lens is made of H-ZK 10.
Scheme (II):
a method for detecting the image quality of a video monitoring camera lens by using a close-up camera is characterized by comprising the following steps: the method comprises the following steps:
a. sequentially arranging a resolution test card, a close-up lens, a video monitoring camera lens and a camera target surface along a light incidence direction, wherein the resolution test card is positioned in a front focus of the close-up lens, the resolution test card forms a virtual image at a longer distance from an object through the close-up lens, and the virtual image is imaged on the camera target surface through the video monitoring camera lens; the close-up lens (R) respectively selects different close-up lenses (R) according to different focal length ranges of the video monitoring camera lens (T) as follows:
(1) when the focal length range of the video monitoring camera lens is 2.5-8mm, the close-up lens uses a close-up lens I, and the position relation between the close-up lens and the video monitoring camera lens is more than 7 and less than delta and less than 10;
(2) when the focal length range of the video monitoring camera lens is 8-20mm, the close-up lens uses a close-up lens II, and the position relation between the close-up lens and the video monitoring camera lens is more than 15 and less than delta and less than 30;
(3) when the focal length range of the video monitoring camera lens is 20-75mm, the close-up lens uses the close-up lens III, and the position relation between the close-up lens and the video monitoring camera lens is more than 15 and less than delta and less than 30;
wherein, delta is the interval from the first surface of the video monitoring camera lens to the close-up lens;
b. the detection personnel judge the imaging quality of the video monitoring camera lens according to the condition of the test card pattern presented on the target surface of the camera or judge the imaging quality of the video monitoring camera lens by using image intelligent software.
Compared with the prior art, the invention has the following advantages:
(1) The close-up lens and the detection method for detecting the image quality of the medium-focus video surveillance camera lens can meet the requirement of detecting the image quality of the video surveillance camera lens within the focal length range of 2.5-75 mm, the addition of the close-up lens does not influence the corrected imaging quality of the video surveillance camera lens, and the close-up lens can lengthen the close object distance and shorten the far object distance, thereby realizing the miniaturization of detection equipment;
(2) According to the method for detecting the image quality of the video monitoring camera lens by using the close-up lens, the longest distance between a common television test card and the close-up lens is not more than 2 meters when the long Jiao Daice lens to be tested is detected on the premise that the corresponding camera device can realize a full-screen test standard condition and the television test cards with different specifications and overlarge areas are less used; when the ultra-wide-angle short-focus lens to be detected is detected, the shortest distance between a test card below a 2# version and a close-up lens is not less than 0.15 meter, so that detection equipment is miniaturized, and detection operation is convenient;
(3) According to the close-up lens for detecting the image quality of the medium-focus video monitoring camera lens, the radius of the No. 2 surface is increased and the close-up lens faces the entrance pupil direction of the lens to be detected under the condition that the secondary spectrum of the close-up lens is not too large by controlling the relative chromatic dispersion difference of the glass pair within a proper range, so that the influence of off-axis aberration on the lens to be detected is reduced, and meanwhile, the correction of on-axis spherical aberration and chromatic spherical aberration is facilitated;
(4) The close-up lens for detecting the image quality of the medium-focus video monitoring camera lens is beneficial to controlling a secondary spectrum, a chromatic spherical aberration and a combined focal length value by selecting the refractive index difference of a certain range of glass pairs;
(5) The method for assisting the video monitoring camera lens in detecting the image quality by utilizing the close-up lens adopts the concept of 'central focal length', uses one close-up lens to adapt to the video monitoring camera lens with a certain focal length range, can ensure the image quality, avoids the trouble of frequently replacing the close-up lens, and can meet the requirement of detecting the image quality of the video monitoring camera lens with the focal length range of 2.5-75 mm by only using three close-up lenses.
Drawings
The invention will be further illustrated with reference to the following examples with reference to the accompanying drawings:
FIG. 1 is a schematic structural diagram of a first close-up mirror of the present invention;
FIG. 2 is a schematic structural diagram of a second close-up mirror of the present invention;
FIG. 3 is a schematic structural diagram of a third objective lens of the present invention;
FIG. 4 is a schematic diagram of the optical principle of the method for detecting the image quality of the video surveillance camera lens with the aid of the close-up lens according to the present invention;
fig. 5 is an MTF graph and a geometric aberration graph of the video surveillance camera lens focal length ft' =4mm after being added to a close-up lens, where fig. 5a is the MTF graph, and fig. 5b to 5e are the geometric aberration graphs;
fig. 6 is an MTF graph (l =2300 mm) of the video monitoring imaging lens focal length ft' =4mm after the close-up mirror is removed;
fig. 7 is an MTF graph of the video surveillance camera lens focal length ft' =6mm after a first close-up lens is added and removed, where fig. 7a is the MTF graph of the first close-up lens added, and fig. 7b is the MTF graph of the first close-up lens removed;
fig. 8 is an MTF graph of the video surveillance camera lens focal length ft' =2.8mm after a first close-up lens is added and removed, where fig. 8a is the MTF graph of the first close-up lens added, and fig. 8b is the MTF graph of the first close-up lens removed;
fig. 9 is an MTF graph and a geometric aberration graph of the video surveillance camera lens with focal length ft' =12mm added to the second close-up mirror, where fig. 9a is the MTF graph, and fig. 9b to 9e are the geometric aberration graphs;
fig. 10 is an MTF graph (l =8430 mm) of the video monitoring imaging lens focal length ft' =12mm with the second close-up mirror removed;
fig. 11 is an MTF graph of the video surveillance camera lens focal length ft' =16mm after adding and removing the second close-up mirror, where fig. 11a is the MTF graph of adding the second close-up mirror, and fig. 11b is the MTF graph of removing the second close-up mirror;
fig. 12 is an MTF graph of the video surveillance camera lens focal length ft' =8mm after adding and removing the second close-up lens, where fig. 12a is the MTF graph of adding the second close-up lens, and fig. 12b is the MTF graph of removing the second close-up lens;
fig. 13 is an MTF graph and a geometric aberration graph of the video surveillance camera lens focal length ft' =35mm after adding to the third close-up mirror, where fig. 13a is the MTF graph, and fig. 13b to 13e are the geometric aberration graphs;
fig. 14 is an MTF graph (l =1980 mm) of the video monitoring imaging lens focal length ft' =35mm with the close-up mirror three removed;
fig. 15 is an MTF graph of the video surveillance camera lens focal length ft' =25mm after adding and removing the third close-up mirror, where fig. 15a is an MTF graph of adding the third close-up mirror, and fig. 15b is an MTF graph of removing the third close-up mirror;
fig. 16 is an MTF graph of the video surveillance camera lens focal length ft' =70mm after adding and removing the third close-up mirror, where fig. 16a is an MTF graph of adding the third close-up mirror, and fig. 16b is an MTF graph of removing the third close-up mirror.
In the above figures: the abscissa relating to the MTF plot is the characteristic frequency, with the coordinate units: line pair/mm; the ordinate curve is the MTF value of the field of view (0 omega, 0.7 omega, 1 omega) at the full aperture and different characteristic frequencies. Spherical aberration curves and astigmatism curves relating to geometric aberration diagrams, the units of the abscissas thereof are: mm; the abscissa unit of the magnification chromatic aberration curve is: mu m; the maximum tangent value of the aperture angle of the abscissa of the meridian characteristic curve and the sagittal characteristic curve is 1; the ordinate represents the maximum value of the dispersion. + -. 20 μm in FIG. 5,. + -. 100 μm in FIG. 9 and. + -. 10 μm in FIG. 13.
The symbols in the drawings illustrate that: 1. the device comprises a first close-up lens, 11, a first lens, 12, a second lens, 2, a second close-up lens, 21, a third lens, 22, a fourth lens, 3, a third close-up lens, 31, a fifth lens, 32, a sixth lens, A, a resolution test card, B, a virtual image, R, a close-up lens, T, a video monitoring camera lens, P and a camera target surface.
Detailed Description
The invention is described in detail below with reference to the drawings and specific examples:
embodiment (a):
as shown in fig. 1 to fig. 3, the close-up lens for detecting the image quality of the mid-focus video surveillance camera lens provided by the present invention is characterized in that: the optical elements of the short-focus video surveillance camera lens, the medium-focus video surveillance camera lens and the long Jiao Shipin surveillance camera lens are respectively detected by a first close-up lens 1, a second close-up lens 2 and a third close-up lens 3, wherein the first close-up lens 1 comprises a first lens 11 and a second lens 12 which forms a close-joint gluing group with the first lens 11, the second close-up lens 2 comprises a third lens 21 and a fourth lens 22 which forms a close-joint gluing group with the third lens 21, the third close-up lens 3 comprises a fifth lens 31 and a sixth lens 32 which forms a close-joint gluing group with the fifth lens 31, and the optical elements forming each close-up lens must meet the following conditions:
0.01＜Pcd12-Pcd11＜0.02；20＜R12/R11＜26‥‥‥①
0.28≦|Φ1/R11-Φ1/R12|‥‥‥②
1.50＜n11＜1.54；60＜ν11＜65‥‥‥③
1.60＜n12＜1.626；35＜ν12＜38‥‥‥④
0.008＜Pcd22-Pcd21＜0.012；4＜|R22/R21|＜6‥‥‥⑤
0.4≦|Φ2/R21-Φ2/R22|‥‥‥⑥
1.50＜n21＜1.54；60＜ν21＜65‥‥‥⑦
1.60＜n22＜1.63；56＜ν22＜61‥‥‥⑧
0.001＜Pcd32-Pcd31＜0.006；8＜|R32/R31|＜12‥‥‥⑨
0.4≦|Φ3/R31-Φ3/R32|‥‥‥⑩
1.57＜n31＜1.1.63；55＜ν31＜59‥‥‥
/>
1.60＜n32＜1.63；56＜ν32＜61‥‥‥
wherein, pcd11, pcd12, pcd21, pcd22, pcd31, pcd32 are relative dispersion coefficients of the first lens 11 to the sixth lens 32 respectively; r11, R12, R13, R21, R22, R23, R31, R32, and R33 are radii of the respective surfaces of the first lens 11 to the sixth lens 32; phi 1-phi 3 are the apertures of the first close-up lens 1-third close-up lens 3 respectively; n11, n12, n21, n22, n31, and n32 are refractive indices of the first lens 11 to the sixth lens 32, respectively; ν 11, ν 12, ν 21, ν 22, ν 31, and ν 32 are abbe coefficients of the first lens 11 to the sixth lens 32, respectively.
The condition (1) is set to control the relative chromatic dispersion difference of the glass pair within a proper range, so that the radius of the 2 nd surface is increased and is enabled to face the direction of the entrance pupil of the lens to be measured under the condition that the secondary spectrum of the short-focus-section close-up lens is not too large, and the influence of the off-axis aberration on the lens to be measured (particularly the ultra-wide-angle short focus) is reduced. Meanwhile, the correction of the spherical aberration and the chromatic spherical aberration on the shaft is facilitated.
The purpose of setting the condition (2) is to ensure a certain edging coefficient, and is beneficial to processing the 1 st lens of the short-focus lens.
Conditions (3), (4) set for the purpose of controlling the secondary spectrum, the chromatic spherical aberration and the combined focal length value by selecting the difference in refractive index for a range of glass pairs.
The condition (5) is set to control the relative chromatic dispersion difference of the glass pair within a proper range, so that under the condition that the secondary spectrum of the close-up lens of the middle focal length is not too large, the radius of the 2 nd surface is increased and is enabled to face the direction of the entrance pupil of the lens to be measured, and the influence of the off-axis aberration on the lens to be measured is reduced. Meanwhile, the correction of the spherical aberration and the chromatic spherical aberration on the shaft is facilitated.
The condition (6) is set to ensure a certain edging coefficient, and is beneficial to processing the 1 st lens of the close-up lens of the middle-focus section.
Conditions (7), (8) set the objective for controlling the secondary spectrum, the chromatic spherical aberration and the combined focal length value by selecting a range of glass to refractive index differences.
The condition (9) is set so that the secondary spectrum becomes small by controlling the relative dispersion difference of the pair of glasses since the telephoto focal length of the telephoto segment is long. The field angle of the long focal length is very small, so that the radius of each surface is not required to face the entrance pupil direction of the lens to be measured, the radius of the second surface can be reduced, the processing is facilitated, and meanwhile, the correction of the on-axis spherical aberration and the chromatic spherical aberration is facilitated.
The condition (r) is set to ensure a certain edging coefficient, which is beneficial to processing the 1 st lens of the telephoto segment.
Condition
The purpose of the settings is to control the secondary spectrum, the chromatic spherical aberration and the combined focal length value by selecting a range of glass to refractive index differences.
Preferably, the first lens 11 is a convex-concave positive lens, and the second lens 12 is a convex-concave negative lens; the third lens 21 is a convex-concave positive lens, and the fourth lens 22 is a convex-concave negative lens; the fifth lens 31 is a positive meniscus lens, and the sixth lens 32 is a negative meniscus lens.
Preferably, the focal length range of the short-focus video surveillance camera lens is 2.5-8mm, the focal length range of the middle-focus video surveillance camera lens is 8-20mm, and the focal length range of the long Jiao Shipin surveillance camera lens is 20-75 mm.
Preferably, the first lens 11 and the third lens 21 are made of H-K9L, the second lens 12 and the fourth lens 22 are made of H-F4, the fifth lens 31 is made of H-ZK3, and the sixth lens 32 is made of H-ZK 10.
Embodiment (b):
as shown in fig. 4, the method for detecting the image quality of a camera lens of a video surveillance camera using a close-up lens according to the present invention is characterized in that: the method comprises the following steps:
a. sequentially arranging a resolution test card A, a close-up lens R, a video monitoring camera lens T and a camera target surface P along a light incidence direction, wherein the resolution test card A is positioned in a front focus of the close-up lens R, the resolution test card A forms a virtual image B at a far distance from an object space through the close-up lens R, and the virtual image B is imaged on the camera target surface P through the video monitoring camera lens T; the close-up lens (R) respectively selects different close-up lenses (R) according to different focal length ranges of the video monitoring camera lens (T) as follows:
(1) when the focal length range of the video monitoring camera lens T is 2.5-8mm, the close-up lens R uses the close-up lens I1, and the position relation between the close-up lens R and the video monitoring camera lens T is more than 7 and less than delta and less than 10;
(2) when the focal length range of the video monitoring camera lens T is 8-20mm, the second close-up lens R is used as the close-up lens R, and the position relation between the close-up lens R and the video monitoring camera lens T is more than 15 and less than delta and less than 30;
(3) when the focal length range of the video monitoring camera lens T is 20-75mm, the close-up lens R uses a close-up lens III 3, and the position relation between the close-up lens R and the video monitoring camera lens T is more than 15 and less than delta and less than 30;
wherein, delta is the interval from the first surface of the video monitoring camera lens T to the close-up lens R;
b. the detection personnel judge the imaging quality of the video monitoring camera lens T according to the situation of the test card pattern presented on the target surface P of the camera or judge the imaging quality of the video monitoring camera lens T by using image intelligent software.
As shown in FIG. 4, wherein A is a close-up view (in the present invention, a resolution test card) placed in the front focus of a close-up mirror R, and B is a "virtual object plane" formed by the view A through the close-up mirror R ". T is the lens to be inspected, through which the "virtual object plane" B is imaged on the target plane P of the camera at a distance Xt' from its back focal point. Let focal length of close-up mirror be f' Near to The focal length ft' of the lens T to be detected; distance from scenery A to close-up lens is | L Near to L; the distance from the first surface of the lens D to be detected to the virtual image B, the distance from the first surface of the lens D to the close-up lens and the distance from the first surface of the lens D to the front main surface of the lens D to be detected are | Lt |,. DELTA and OHt respectively. As | Lt>>OHt, it can be considered that | Lt | + OHt is approximately equal to | Lt |. Let the size of the object plane be phi A, the size of the 'virtual object plane' of the close-up lens be phi B, and the size of the target plane of the camera be phi C. The relationship between the magnification ratios is set as M | = | PhiA |/| PhiB |, | MR | = | PhiA |/| PhiP |, | MT | = | PhiB |/| PhiP |, and
from the optical imaging relationship, the following formula can be derived:
[ magnification ratio between close-up mirror object image surfaces | = |1- (| Lt | - [ delta ])/' Near to |
The magnification relationship is as follows: | MR | = | M |. MT |)
The focal length of the close-up lens: f' Near to ＝|MR|*(|Lt|-△)*ft′/[(|Lt|-ft′)-|MR|*ft′]
(4) Distance between close-up lens and scenery (scenery is actually television resolution survey card):
|L near to |＝|(-|Lt|+△)*f′ Near to /(-|Lt|+△+f′ Near to )|
All | Lt |,. DELTA., ft' in the above formula are given known amounts. According to the actual detection requirement, | Lt | can take 2 to 3.5m when the focal length ft' of the lens T to be detected is 2 to 6 mm; when ft' is from 8 to 16mm, | Lt | may take from 2.5 to 4.5m; when ft' is above 25mm, | Lt | may take 3.5m or more. When the delta is in the short focal length lens to be detected, the aperture of the close-up lens is large due to the large field angle, which is not beneficial to processing, but too small is not beneficial to assembling and disassembling the lens to be detected, and is generally about 7-10 mm; for a lens to be detected with ft' being more than 8mm, more than 15mm can be used. One necessary condition in the test method using TV resolution test card is that the TV resolution test card must be full of target in the image of target surface of camera device through the lens to be tested, so that the | MR | can be selected from the sizes of test card and camera device and their relationThe process is carried out. Thus, the required f' near sum | L can be obtained according to the formula Near to L. Generally, through a listing method, lenses ft ' with different focal lengths to be detected, camera devices | phi P | with different sizes, television resolution test card sizes | phi a | with different specifications and different distances | Lt | from the first surface to the virtual image surface of the lens T to be detected are shown, and a proper f ' is found ' Near to And | L Near to Initial value of | is calculated. The example table takes a 4:3 specification # 1 tv resolution test card as an example, which is 280mm x 220mm in size and 356mm in diagonal length. CMOS size: 1/3 '(phi 6 mm), 1/2.7' (phi 6.6 mm), 1/2.5 '(phi 7.2 mm), 1/2' (phi 8 mm), 1/1.8 '(phi 8.9 mm), 2/3' (phi 11 mm). Partial results of the calculations are shown in table 1:
table 1 units: mm is
From the above table analysis of the calculated results it follows that:
1. with the increase of the imaging device, the focal length f' of the close-up lens and the absolute value L of the close-up lens required to be selected are reduced; however, as the focal length of the lens to be measured increases, the focal length f' of the close-up lens and | L close | to be selected also increase and become even negative. For the lens to be tested with large view field and large target surface, correspondingly selecting a large test card is beneficial; for the long-focus lens to be tested, it is advantageous to select a small-sized test card, but care should be taken to prevent | L from being close to | and being too long (which may affect the miniaturization of the device).
2. From the table, under the condition that the scene A and the virtual object surface B are required to mutually form a positive image, the calculated f 'is far larger than ft', and the deflection angles on the axis and outside the axis borne by the visible close-up lens are not large, so that the influence of the visible close-up lens on the corrected image quality of the lens to be measured cannot be large. Since f is large, the color spherical aberration (especially the second order spectrum) must be large, which is noticeable when correcting the difference of close-up images.
Because the individually optimized close-up lens is difficult to reflect the imaging effect of combining the close-up lens with the rear lens to be measured, the method adopted by the invention is to connect the initially designed close-up lens structure with the lens to be measured with the same focal length, different fields of view, different calibers and different lens structures for optimization calculation, namely under the condition that the parameters of the lens to be measured are not changed, the back intercept of the combined lens and the parameters of the close-up lens are changed for aberration balance, and a new structure of the optimized close-up lens is obtained; and then, under the condition of not changing the new back intercept, taking off the close-up lens, readjusting the object distance, and calculating the imaging quality of the lens to be detected at the moment, wherein if the imaging quality is better, the object distance also meets the design requirement, and the close-up lens which can be suitable for detecting various types of lenses to be detected with the same focal length can be selected preferentially. The method is simple and feasible, and proved by practice, not only solves the imaging effect that an independently optimized close-up lens is difficult to react and a rear lens to be detected is combined, but also avoids the problem that different lens structures to be detected cause aberration and other parameter changes due to different front main surfaces.
Theoretically, one close-up lens has the best imaging effect corresponding to the lens to be measured with the same focal length value, the same relative aperture and the same distance of the virtual object plane B, but the close-up lens is unreasonable in terms of processing cost. Formula for calculating focal length from the close-up lens:
f′ near to ＝|MR|*(|Lt|-△)*ft′/[(|Lt|-ft′)-|MR|*ft′]
It can be derived that: ft '= f' near | Lt |/[ (| Lt | -. Δ + f 'near) | MR | + f' near ] (where | MR | = | Φ a |/| Φ P |). In the above formula, if the same close-up lens is used, the lenses to be tested with different focal lengths can be detected by changing the | MR | and | Lt | values, that is, the size of the test card and the | Lt | value can be changed to detect the lenses to be tested with different focal lengths when the size of the target surface of the camera is determined. However, according to a lot of calculations, when a designed close-up lens is intended to adapt to the aberration of the lens to be measured with a large range of focal lengths, the image quality will change greatly. Therefore, it is not appropriate to use a close-up lens to detect the aberration of the lens to be measured over a wide range of focal lengths. However, it is feasible to use a close-up lens to adapt to the detection of the lens to be detected within a certain focal length range, so that one lens can be used for multiple purposes. When selecting the proper focal length range of the close-up lens, the concept of ' central focal length ' is adopted, for example, the central focal length ft ' =4mm selected from a short focal length, which can meet the detection of a lens to be detected with the focal length of 2.5-8 mm; the central focal length ft' =12mm selected from the middle focus, and the detection of a lens to be detected with the focal length of 8-20mm can be met; the central focal length ft' =35mm selected by the long focus, and the long focus can meet the detection of a lens to be detected with the focal length of 20-75 mm. When the aberration is balanced, the correction is performed based on the selected center focal length. Therefore, the detection of the imaging quality of the lens to be detected from 2.5mm to 75mm in focal length is met by only adopting three groups of double-cemented lens combinations.
Example 1:
the close-up lens comprises a first close-up lens 1, a second close-up lens 2 and a third close-up lens 3 which are respectively arranged at the front ends of short, medium and long focal lengths of a video monitoring camera lens to be detected and used for assisting the image quality detection of the video monitoring camera lens.
Short focal length range suitable close-up mirror 1 is composed of focal length of f' Near to =337.8mm, two pieces of convex and concave lens are cemented together, and the focal lengths of the front and rear lenses are respectively 103 and-140.1 mm. The radius of the lens is R11, R12 and R13 respectively; the thicknesses are d11 and d12 respectively; the optical materials are respectively H-K9L and H-F4. Wherein, the selected R12 is about 20-26 times of the R11, and all the radiuses face the entrance pupil of the lens to be measured, so as to be beneficial to reducing the influence of off-axis aberration. By adopting the scheme, the problem that the edging coefficient is too small can be solved while the imaging quality is well corrected. As shown in fig. 1. The invention selects ft' =4mm as the central focal length of the short-focus lens to be measured, and the D/f =1:2; the image plane size Φ 6.6mm, FIG. 6 is its MTF curve at an object distance of 2300 mm.
Table 2 lists the geometrical parameter changes of the lenses to be detected in the short focus range with the addition and removal of the close-up lens.
Table 2: f' =337.8mm units: mm (mm)
The second close-up lens 2 with the middle focal length range applicable is formed by gluing two lenses with the focal length f' close =1033mm and convex-concave shapes, and the focal lengths of the front lens and the rear lens are 297.5 mm and-408.7 mm respectively. The radii of the lens are R21, R22 and R23 respectively; the thicknesses are d21 and d22 respectively; the optical materials are H-K9L and H-F4 respectively. Wherein R22 is selected to be about 4-6 times greater than R21. By the scheme, the problem that the edging coefficient is too small is solved while the imaging quality is well corrected. (as shown in fig. 2). The invention selects ft' =12mm as the central focal length of the lens to be measured of the middle focus, and the D/f =1:2; the image plane size Φ 6.6mm, FIG. 6 is its MTF curve at an object distance of 8430 mm. Table 3 lists the changes in the addition and removal of the paraxial lens from several lenses to be tested in the mid-focus range:
table 3: f' near =1033mm units: mm is
The third lens 3 suitable for the long focal length range is formed by gluing two concave-convex lenses with the focal length f' close =2085 mm. The focal lengths of the front and rear lenses are 111.9 and-119.03 mm, respectively. The radii of the lens are R31, R32 and R33 respectively; the thicknesses are d31 and d32 respectively; the optical materials are respectively H-ZK3 and H-ZK 10. Wherein R31 is selected to be about 8-12 times greater than R32. Because the focal length is long, the radiuses of the front and the rear surfaces are very large, and if a design method of short and medium focuses is adopted, the radius of a gluing surface is very large, so that the edging coefficient is very small. The close-up lens with the applicable long focal length range adopts the scheme that the front surface and the back surface do not face the entrance pupil of the lens to be measured, so that the radius of the gluing surface becomes very small, and the problem of over-small edging coefficient is solved while the imaging quality is corrected. (as shown in fig. 3). The invention selects ft' =35mm as the central focal length of the long-focus lens to be measured, and the D/f =1:2; the image plane size Φ 6.6mm, and FIG. 6 is the MTF curve at object distance 1980 mm. Table 4 lists the change of the addition and removal of the close-up lens for several lenses to be detected in the short focus range:
table 4: f' near =2084.8mm units: mm is
The above embodiments are merely illustrative of the technical solutions of the present invention, and the present invention is not limited to the above embodiments, and any modifications or alterations according to the principles of the present invention should be within the protection scope of the present invention.
Claims (3)
1. A close-up lens for detecting the image quality of a middle-focus video monitoring camera lens is characterized in that: the optical element of the second close-up lens (2) is composed of a second close-up lens (2) for detecting the mid-focus video monitoring camera lens, wherein the second close-up lens (2) is composed of a third lens (21) and a fourth lens (22) which is in close-joint gluing combination with the third lens (21), and the optical element of the second close-up lens (2) must meet the following conditions:
0.008＜Pcd22-Pcd21＜0.012；4＜|R22/R21|＜6‥‥‥⑤
0.4≦|Φ2/R21-Φ2/R22|‥‥‥⑥
1.50＜n21＜1.54；60＜ν21＜65‥‥‥⑦
1.60＜n22＜1.63；56＜ν22＜61‥‥‥⑧
wherein Pcd21 and Pcd22 are relative dispersion coefficients of the third lens (21) and the fourth lens (22), respectively; r21, R22 and R23 are respectively the radius of each surface of the third lens (21) and the fourth lens (22); phi 2 is the caliber of the close-up lens II (2); n21 and n22 are refractive indexes of the third lens (21) and the fourth lens (22), respectively; ν 21 and ν 22 are abbe coefficients of the third lens (21) and the fourth lens (22), respectively;
the focal length of the second close-up lens (2) is 1033mm, the focal length range of the middle-focus video monitoring camera lens is 8-20mm, and the position relation of the second close-up lens (2) and the middle Jiao Shipin monitoring camera lens is more than 15 and less than delta and less than 30; wherein delta is the interval from the first surface of the middle-focus video monitoring camera lens to the second close-up lens (2);
the third lens (21) is a convex-concave positive lens, and the fourth lens (22) is a convex-concave negative lens.
2. The close-up lens for image quality detection of the mid-focus video surveillance camera lens according to claim 1, characterized in that: the third lens (21) is made of H-K9L, and the fourth lens (22) is made of H-F4.
3. A method for assisting image quality detection of a video surveillance camera lens by using a close-up lens according to any one of claims 1-2, wherein the method comprises the following steps: the method comprises the following steps:
a. arranging a resolution test card (A), a close-up lens (R), a video monitoring camera lens (T) and a camera target surface (P) in sequence along a light incidence direction, wherein the resolution test card (A) is positioned in a front focus of the close-up lens (R), the resolution test card (A) forms a virtual image (B) at a far distance from an object space through the close-up lens (R), the virtual image (B) is imaged on the camera target surface (P) through the video monitoring camera lens (T), and the close-up lens (R) is a second close-up lens (2);
b. the detection personnel judge the imaging quality of the video monitoring camera lens (T) according to the condition of the test card pattern presented on the target surface (P) of the camera or judge the imaging quality of the video monitoring camera lens (T) by using image intelligent software.
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| CN201710680696.0A CN107272159B (en) | 2017-08-10 | 2017-08-10 | Close-up lens for assisting image quality detection of video surveillance camera lens and detection method |
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| JP2001242377A (en) * | 2000-02-28 | 2001-09-07 | Toshiba Corp | Lens and camera module |
| JP2003006908A (en) * | 2001-06-19 | 2003-01-10 | Matsushita Electric Ind Co Ltd | Recording/reproducing optical system, objective lens and optical head device |
| JP2003005033A (en) * | 2001-06-21 | 2003-01-08 | Minolta Co Ltd | Optical pickup lens |
| JP2006286109A (en) * | 2005-04-01 | 2006-10-19 | Fujinon Sano Kk | Collimator lens for optical pickup |
| TWI282900B (en) * | 2005-06-10 | 2007-06-21 | Dual Halo Technology Co Ltd | Optical system for shortening optical path |
| JP4898361B2 (en) * | 2006-09-12 | 2012-03-14 | キヤノン株式会社 | Teleconverter lens and imaging apparatus having the same |
| CN104075881B (en) * | 2014-07-01 | 2016-08-24 | 西安应用光学研究所 | It is applicable to multiband light path telescopical parallel error measuring method altogether |
| CN105093504A (en) * | 2015-06-30 | 2015-11-25 | 深圳海偲科技有限公司 | Macro lens |
| CN105716831B (en) * | 2016-02-05 | 2018-11-02 | 中国科学院西安光学精密机械研究所 | A kind of object simulation device system of big visual field super big dynamic range object distance |
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