JP5382565B2 - Lens system - Google Patents

Description

  The present invention relates to a lens system in a high-magnification zoom lens system, and more particularly to a lens system that enables photographing in the near-infrared region by inserting an image position correcting optical system into a zoom lens capable of photographing in the visible region.

In recent years, with the spread of small video cameras, optical systems for monitoring purposes have become widespread. Among them, various optical systems that make use of the characteristics of light in the near-infrared region are required and are beginning to be commercialized. While shooting using natural light such as sunlight and illumination light in the visible range during the day and at night, it is possible to shoot using irradiation light in the near infrared range. An example is an optical system. In such an optical system, the axial chromatic aberration from the visible range to the near infrared range is corrected, that is, the optical system is adjusted by making the focal length in the visible range and the focal length in the near infrared range as close as possible. Therefore, it is necessary to have an optical characteristic that enables an image to be obtained in a focused state regardless of day or night. An optical system having such optical characteristics has become common as a day / night combined lens (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent Laying-Open No. 2005-227507 JP 2006-91643 A

  Recently, remote outdoor day / night monitoring systems, which are in great demand for border monitoring, etc., and monitoring systems that can capture images in dense fog that cannot be captured at visible wavelengths even during the day, using wavelengths in the near infrared range, etc. Therefore, there is a demand for a lens system that enables photographing in the near-infrared region in a high-magnification zoom lens system that covers even super telephoto.

However, what has been proposed in Patent Document 1 and Patent Document 2 can be applied to a wide-angle zoom lens having a short focal length relatively easily, and it is difficult to correct chromatic aberration. There is a problem that it is very difficult to apply to the optical system of a high-magnification zoom lens that covers up to the near-infrared range.
For example, the above-mentioned problem can be reduced by using extremely expensive extraordinarily low dispersion materials such as fluorite, but the image position shift in the near infrared region is corrected while satisfying the high performance in the visible region. Is not enough. In addition, the difference in image position between the visible and near-infrared regions when a variable power optical system such as a teleconverter is inserted becomes more conspicuous, making it even more difficult to correct image position shifts in the near-infrared region. There is also a problem of becoming.

  The present invention has been proposed in view of the above circumstances, and by inserting an image position correction optical system into a zoom lens system capable of photographing in the visible range (particularly, a high-magnification zoom lens system that covers even the super telephoto), An object of the present invention is to provide a lens system that enables photographing in the infrared region, and enables daytime and night surveillance systems in the distance and photographing in dense fog.

In order to achieve the above object, a lens system according to the present invention includes a focusing system lens group that is positioned closest to the object side, and a zoom that is positioned closer to the image plane side than the focusing system lens and moves linearly according to zooming. a system lens, positioned at the image plane side of the zoom system lens group, and the correction system lens group which curves move in accordance with zooming, the imaging system you located on the image side than the correcting system lens group A lens system having a zoom lens having a lens group, capable of photographing for wavelengths from the visible range to the near infrared range, and having a single image plane, between the lens groups constituting the imaging system lens group And a teleconverter, and an image position correcting optical system which is composed of two groups and is inserted closer to the image plane side than the imaging system lens group .

In particular, the two groups of the image position correcting optical system are either in the order of the fixed group and the moving group from the image plane side, in the order of the moving group, in the order of the fixed group, or in the order of the moving group and the moving group. It is preferable that one of these is selected.

Moreover, zooming, focusing, adjustment of the photographic wavelength region (switching), depending on the change in the optical conditions that occur upon insertion of the variable power optical system, the distance between the two groups of the image position correction optical system is adjusted, visible It is preferable that photographing can be performed in the near-infrared region while maintaining the same distance between the position of the imaging system lens group and the image plane when photographing at the same time .

Then, two of each group of the group constituting the image position correcting optical system is more preferably a benzalkonium that having a positive and negative different power each other.

The present invention provides a focusing lens group that is located closest to the object side, a zooming lens group that is positioned closer to the image plane side than the focusing lens, and moves linearly in response to zooming, and an image than the zooming lens group. located on the side, with a correcting system lens group which curves move in response to the zooming, the zoom lens having an imaging system lens group you located on the image side than the correcting system lens group, a near infrared regions It is a lens system that can shoot at wavelengths up to 1 and has a single image plane. It consists of two groups, a teleconverter that is inserted and removed between the lens groups that form the imaging system lens group, and forms an image. because it has an image position correcting optical system than the system lens is inserted into the image plane side, when switching from the visible range photographing mode in the near infrared range photographing mode, the configured image position correction optical system in two groups , Zoom By inserting the lens closer to the image plane than the imaging system lens group, the image position shift caused by switching from the visible range shooting mode to the near infrared range shooting mode can be corrected. An image in a focused state can be obtained. In particular, since it can cover up to super-telephoto, it is possible to correct image position deviation even in a high-magnification zoom lens system with a long focal length, and to obtain a focused image regardless of day or night. Can be provided.

In particular, the two groups of the image position correcting optical system are either in the order of the fixed group and the moving group from the image plane side, in the order of the moving group, in the order of the fixed group, or in the order of the moving group and the moving group. since either one of the order of what is selected, when switching from the visible region shooting mode in the near infrared range photographing mode, the configured image position correction optical system in two groups, than the imaging system lens group in the zoom lens By inserting it on the image plane side and adjusting the moving group, the image position shift due to switching from the visible range shooting mode to the near infrared range shooting mode can be corrected appropriately. It is possible to obtain an image in a focused state. In addition, since it can cover up to super-telephoto, it is possible to correct image position deviation even in a high-magnification zoom lens system with a long focal length, and to obtain a focused image regardless of day or night. Can be provided.

Furthermore, in the above lens system, the distance between the two groups of the inserted image position correction optical system can be adjusted according to the optical conditions that change when zooming, focusing, adjustment of the imaging wavelength (switching), and insertion of the variable magnification optical system. Therefore, even when optical conditions change during zooming, focusing, imaging wavelength adjustment (switching), and insertion of a variable magnification optical system, it is possible to correct image position deviation. That is, for example, the image position in the near-infrared region changes according to zooming or focusing, but by adjusting the distance between the two groups of the inserted image position correction optical system, the changed image position can be determined. Since it can be moved to a fixed image position determined by the flange back, a focused image can be obtained over the entire zoom range, even in the near-infrared region. In addition, it is possible to shoot in the near-infrared region while maintaining the same distance between the position of the imaging system lens group and the image plane when shooting in the visible region.

Further, two of each group of the group constituting the image position correction optical system than that having a positive and negative different power, and can be kept small amount of movement of the moving unit at the time of image position correcting optical system inserted Become.

  As described above, according to the present invention, in the lens system used in the visible range, by inserting a simple optical system called an image position correction optical system, and further adjusting the group interval to vary the focal length, An effective effect of being able to focus on wavelengths from the visible range to the near infrared range is obtained. In the image position correcting optical system with a wavelength in the near-infrared region thus inserted, even an existing zoom lens that does not consider photographing in the near-infrared region can be inserted if the insertion space can be secured. Therefore, it is possible to provide a wide range of lens systems that can obtain a focused image regardless of day or night even in the near infrared region.

Hereinafter, it demonstrates concretely, referring drawings (FIGS. 1-37) as an example on implementing this invention.
In addition, description here is an example of embodiment of this invention, Comprising: It is not limited to the following embodiment (Examples 1-4). The present invention can be modified in various ways without departing from the scope of the claims.

Example 1
As shown in FIG. 1, the present invention includes a high-magnification zoom lens 10 having a focal length of at least 500 mm, which has an imaging system lens group composed of one or more, for example, ten lenses. , A lens system 1 capable of photographing with respect to wavelengths from the visible range to the near-infrared range, and an image position correcting optical system composed of two groups, for example, in order of a fixed group and a moving group from the image plane side In the zoom lens 10, the image position correcting optical system 30 configured by selecting any one of the moving group, the moving group, the fixed group or the moving group, the moving group is selected. This is inserted on the image plane side from the image plane side fixed group 14 as an imaging system lens group composed of the above lenses. Further, the lens system 1 can adjust the distance between the two groups of the image position correcting optical system 30, and can be used for zooming, focusing, imaging wavelength range adjustment (switching), and as a variable power optical system, for example, a teleconverter 20. In accordance with changes in various optical conditions that occur upon insertion, the group interval of the image position correcting optical system 30 can be adjusted to correct the image position shift of the imaging wavelength. Further, each group constituting the image position correction optical system 30, for example, two groups of insert front 31, insert the rear 32 are have a positive and negative different power (refractive power).
In FIG. 1, IMG indicates an image plane, and is composed of an image sensor such as a CCD or a CMOS. FP indicates a filter, and is composed of, for example, a protective glass or an optical low-pass filter.

  The lens system 1 includes an object-side fixed group 11 as a focusing lens that is positioned closest to the object side including the focus group 11A, and is positioned closer to the image plane IMG than the object-side fixed group 11, and moves linearly according to zooming. A first moving group 12 as a variable power system lens, a second moving group 13 as a correction system lens that is positioned on the image plane IMG side relative to the first moving group 12 and moves in a curve according to zooming, this second movement In order to shift the zoom focal range to the telephoto side, and the zoom lens 10 including the image plane side fixed group 14 as an imaging system lens positioned on the image plane IMG side relative to the group 13, the image plane side fixed group 14 is Teleconverter 20 inserted / extracted between constituting lens groups, and an image position correcting optical system constituted by two groups, for example, an insertion part front side 31 as a fixed group, and an insertion part as a moving group 32 consists of two groups of have, the image position correction optical system 30 to be inserted into the image plane IMG side of the image plane side fixed group 14. The zoom ratio is, for example, 51.8 times. For example, a teleconverter 20 having a magnification of 2 is employed.

  Examples of numerical values of the respective lenses employed in the zoom lens 10 in the lens system 1 according to the present invention are shown in Table 1, numerical examples of A, B, and C in Table 1 are shown in Table 2, and numerical examples of the respective lenses employed in the teleconverter 20 Are shown in Table 3, respectively. In Tables 1 and 3, R is the radius of curvature, d is the distance between the lenses, Nd is the refractive index of the d-line (wavelength 587.56 nm), νd is the Abbe number, and inf is infinity. In Table 2, WIDE indicates a wide angle (focal length 10.3 mm), and TELE indicates a telephoto state (focal length 533.5 mm).

  When photographing in the near infrared region, the image position correcting optical system 30 shown in FIG. 2 is inserted behind the image plane side fixed group 14 of the zoom lens 10 with an air gap of 3 mm. At that time, the distance D between the insertion portion front side 31 and the insertion portion rear side 32 of the image position correction optical system 30 is moved (changed) in conjunction with the zoom position, the object distance, and the imaging wavelength. It is possible to cope with photographing in the near infrared region while keeping the position of the image plane side fixed group 14 and the image surface IMG at the same interval during photographing in the visible region. In the first embodiment, as shown in FIG. 2, the insertion portion front side 31 of the image position correction optical system 30 is a fixed group, and the insertion portion rear side 32 is a moving group.

  Table 4 shows the configuration of each lens employed in the image position correction optical system 30 in Example 1, and Table 5 shows the power (refractive power) of the insertion portion front side 31 and the insertion portion rear side 32 of the image position correction optical system 30. Shown in In Table 4, R is the radius of curvature, d is the distance between lenses, Nd is the refractive index of the d-line (wavelength 587.56 nm), νd is the Abbe number, and inf is infinite. D corresponds to the interval D in Table 6.

  From Table 5, the image position correction optical system 30 of this embodiment is composed of groups having positive and negative powers (refractive powers), so that the amount of movement of the moving group when the image position correction optical system is inserted can be kept small. It becomes.

  3 to 10 are spherical aberration diagrams according to the first embodiment. FIG. 3A is a spherical aberration diagram in the state where only the zoom lens 10 or the zoom lens 10 and the teleconverter 20 are used. FIGS. 7A and 7C are spherical aberration diagrams when the image position correcting optical system 30 is inserted into the zoom lens 10 or the zoom lens 10 and the teleconverter 20. In this case, the distance D between the insertion portion front side 31 and the insertion portion rear side 32 constituting the image position correction optical system 30 is as shown in Table 6 below. The scale is mm, and the position of 0.0 in each graph corresponds to the image plane IMG position described in FIG.

  FIG. 3 shows the performance of the zoom lens 10 when the object distance is infinite with the focal length 10.3 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 2.33 mm. It is apparent from (c) that the image position deviation at the wavelength of 960 nm is corrected by setting the distance D to 2.50 mm.

  FIG. 4 shows the performance of the zoom lens 10 when the object distance is infinite while the focal length is 533.5 mm on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 2.90 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 3.25 mm.

  FIG. 5 shows the performance of the zoom lens 10 when the object distance is 5000 mm with the widest angle of 10.3 mm. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 2.33 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D to 2.53 mm.

  FIG. 6 shows the performance of the zoom lens 10 when the object distance is 5000 mm on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 3.31 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D to 3.77 mm.

  FIG. 7 shows the performance of the zoom lens 10 in a state where the teleconverter 20 is inserted in the state where the object distance is infinite on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 3.32 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 4.13 mm.

  FIG. 8 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in an infinite object distance on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 5.85 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 7.58 mm.

  FIG. 9 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in the state where the object distance is 5000 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 3.33 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 4.14 mm.

  FIG. 10 shows the performance when the teleconverter 20 is inserted in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens 10. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D to 7.71 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 10.00 mm.

  Table 6 summarizes the above. In Table 6, 10 indicates a state in which the teleconverter 20 is not inserted into the zoom lens 10 in the lens system 1 according to the first embodiment, and 10 + 20 indicates that the teleconverter 20 is added to the zoom lens 10 in the lens system 1 according to the first embodiment. Each inserted state is shown.

(Example 2)
In the second embodiment, the same configuration as the image position correcting optical system 30 described in the first embodiment is inserted behind the image plane side fixed group 14 of the zoom lens 10 with an air gap of 3 mm. At that time, the distance D1 between the image plane side fixed group 14 portion of the zoom lens 10 and the insertion portion front side 31 of the image position correcting optical system 30, and the interval D2 between the insertion portion front side 31 and the insertion portion rear side 32 are set as the zoom position, the object By moving (changing) in conjunction with the distance and the imaging wavelength, imaging in the near infrared region while keeping the position of the image plane side fixed group 14 and the image plane IMG at the same interval during imaging in the visible range. It is also possible to correspond. However, in the second embodiment, as shown in FIG. 11, the image position correcting optical system 30 has both the insertion portion front side 31 and the insertion portion rear side 32 as moving groups.
The configurations of the zoom lens 10 and the teleconverter 20 are the same as those in the first embodiment.

  FIGS. 12 to 19 are spherical aberration diagrams according to the second embodiment. FIG. 12A is a spherical aberration diagram in the state where only the zoom lens 10 or the zoom lens 10 and the teleconverter 20 are used. FIGS. 7A and 7C are spherical aberration diagrams when the image position correcting optical system 30 is inserted into the zoom lens 10 or the zoom lens 10 and the teleconverter 20. In this case, the distance D1 between the image plane side fixed group 14 portion of the zoom lens 10 and the insertion portion front side 31 of the image position correcting optical system 30 and the interval D2 between the insertion portion front side 31 and the insertion portion rear side 32 are shown in Table 7 below. It is as follows. The scale is mm, and the position of 0.0 in each graph corresponds to the image plane IMG position described in FIG.

  FIG. 12 shows the performance of the zoom lens 10 when the focal length is 10.3 mm on the widest angle side and the object distance is infinite. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 3.00 mm and the distance D2 to 2.30 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the interval D1 to 3.00 mm and the interval D2 to 2.50 mm.

  FIG. 13 shows the performance of the zoom lens 10 in the state where the focal length is 533.5 mm on the most telephoto side and the object distance is infinite. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is apparent from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 1.72 mm and the distance D2 to 2.92 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D1 to 1.72 mm and the distance D2 to 3.29 mm.

  FIG. 14 shows the performance of the zoom lens 10 when the object distance is 5000 mm with the most wide angle 10.3 mm. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 3.00 mm and the distance D2 to 2.33 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the interval D1 to 3.00 mm and the interval D2 to 2.52 mm.

  FIG. 15 shows the performance when the object distance is 5000 mm on the most telephoto side of the zoom lens 10. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 1.72 mm and the distance D2 to 3.29 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D1 to 1.72 mm and the distance D2 to 3.73 mm.

  FIG. 16 shows the performance of the zoom lens 10 in a state where the teleconverter 20 is inserted in a state where the object distance is infinite on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 3.00 mm and the distance D2 to 3.30 mm. It is apparent from (c) that the image position deviation at the wavelength of 960 nm is corrected by setting the distance D1 to 3.00 mm and the distance D2 to 4.11 mm.

  FIG. 17 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in a state where the object distance is infinite on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is apparent from (b) that the image position deviation at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 1.72 mm and the distance D2 to 5.72 mm. It is apparent from (c) that the image position deviation at the wavelength of 960 nm is corrected by setting the distance D1 to 1.72 mm and the distance D2 to 7.35 mm.

  FIG. 18 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in the state where the object distance is 5000 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 3.00 mm and the distance D2 to 3.30 mm. It is apparent from (c) that the image position deviation at the wavelength of 960 nm is corrected by setting the distance D1 to 3.00 mm and the distance D2 to 4.11 mm.

  FIG. 19 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in a state where the object distance is 5000 mm on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 30 and setting the distance D1 to 1.72 mm and the distance D2 to 7.46 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D1 to 1.72 mm and the distance D2 to 9.61 mm.

  Table 7 summarizes the above. In Table 7, 10 indicates a state in which the teleconverter 20 is not inserted into the zoom lens 10 in the lens system 1 according to the second embodiment, and 10 + 20 indicates that the teleconverter 20 is inserted into the zoom lens 10 in the lens system 1 according to the second embodiment. Each state is shown.

(Example 3)
In the third embodiment, when photographing in the near infrared region, the image position correcting optical system 40 shown in FIG. 20 is inserted behind the image plane side fixed group 14 part of the zoom lens 10 with an air interval of 3 mm. At this time, the distance D between the insertion portion front side 41 and the insertion portion rear side 42 of the image position correction optical system 40 is moved (changed) in conjunction with the zoom position, the object distance, and the imaging wavelength, thereby making the visible region visible. It is possible to cope with photographing in the near-infrared region while keeping the position of the image plane side fixed group 14 and the image plane IMG at the same interval at the time of photographing. In the third embodiment, as shown in FIG. 20, the insertion portion front side 41 of the image position correction optical system 40 is a fixed group, and the insertion portion rear side 42 is a moving group.
The configurations of the zoom lens 10 and the teleconverter 20 are the same as those in the first embodiment.

  Table 8 shows the configuration of each lens employed in the image position correction optical system 40 in Example 3, and Table 9 shows the power (refractive power) of the insertion portion front side 41 and the insertion portion rear side 42 of the image position correction optical system 40. Shown in In Table 8, R is the radius of curvature, d is the distance between the lenses, Nd is the refractive index of the d-line (wavelength 587.56 nm), νd is the Abbe number, and inf is infinite. D corresponds to the interval D in Table 10.

  From Table 9, since the image position correction optical system 40 of the third embodiment is composed of groups having different positive and negative powers, the movement amount of the moving group when the image position correction optical system is inserted can be kept small.

  21 to 28 are spherical aberration diagrams according to the third embodiment, and FIG. 21A is a spherical aberration diagram in the state where only the zoom lens 10 or the zoom lens 10 and the teleconverter 20 are used. And (c) are spherical aberration diagrams when the image position correcting optical system 40 is inserted into the zoom lens 10 or the zoom lens 10 and the teleconverter 20. At this time, the distance D between the insertion portion front side 41 and the insertion portion rear side 42 constituting the image position correction optical system 40 is as shown in Table 10 below.

  FIG. 21 shows the performance of the zoom lens 10 when the object distance is infinite while the focal length is 10.3 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 12.27 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 11.98 mm.

  FIG. 22 shows the performance of the zoom lens 10 when the object distance is infinite while the focal length is 533.5 mm on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 11.32 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 10.82 mm.

  FIG. 23 shows the performance of the zoom lens 10 when the object distance is 5000 mm with the widest angle of 10.3 mm. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 12.27 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 11.98 mm.

  FIG. 24 shows the performance when the object distance is 5000 mm on the most telephoto side of the zoom lens 10. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 10.70 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 10.06 mm.

  FIG. 25 shows the performance of the zoom lens 10 in a state where the teleconverter 20 is inserted in the state where the object distance is infinite on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 10.72 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 9.59 mm.

  FIG. 26 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in a state where the object distance is infinite on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 7.17 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D to 5.06 mm.

  FIG. 27 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in the state where the object distance is 5000 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 10.72 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 9.59 mm.

  FIG. 28 shows the performance in a state where the teleconverter 20 is inserted in the state where the object distance is 5000 mm on the most telephoto side of the zoom lens 10. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 40 and setting the distance D to 4.83 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 2.51 mm.

  Table 10 summarizes the above. In Table 10, 10 indicates a state in which the teleconverter 20 is not inserted into the zoom lens 10 in the lens system 1 according to the third embodiment, and 10 + 20 indicates that the teleconverter 20 is inserted into the zoom lens 10 in the lens system 1 according to the third embodiment. Each state is shown.

Example 4
In the fourth embodiment, when photographing in the near infrared region, the image position correcting optical system 50 shown in FIG. 29 is inserted with an air gap of 17.93 mm from the image plane IMG. At that time, the distance D between the insertion portion front side 51 and the insertion portion rear side 52 of the image position correction optical system 50 is moved in conjunction with the zoom position, the object distance, and the imaging wavelength, thereby enabling the imaging in the visible range. It is possible to cope with photographing in the near infrared region while keeping the position of the image plane side fixed group 14 and the image plane IMG at the same interval. In the fourth embodiment, as shown in FIG. 29, the insertion portion front side 51 of the image position correction optical system 50 is a moving group, and the insertion portion rear side 52 is a fixed group.
The configurations of the zoom lens 10 and the teleconverter 20 are the same as those in the first embodiment.

  Table 11 shows the configuration of each lens employed in the image position correction optical system 50 in Example 4, and Table 12 shows the power (refractive power) of the insertion portion front side 51 and the insertion portion rear side 52 of the image position correction optical system 50. Shown in In Table 11, R is the radius of curvature, d is the distance between the lenses, Nd is the refractive index of the d-line (wavelength 587.56 nm), νd is the Abbe number, and inf is infinite. D corresponds to the interval D in Table 13.

  From Table 12, since the image position correcting optical system 50 of the fourth embodiment is composed of groups having different positive and negative powers, the moving amount of the moving group when the image position correcting optical system is inserted can be kept small.

  30 and the subsequent drawings are spherical aberration diagrams according to the fourth embodiment, and FIG. 30A is a spherical aberration diagram in a state where only the zoom lens 10 or the zoom lens 10 and the teleconverter 20 are used, and FIGS. ) Is a spherical aberration diagram when the image position correcting optical system 50 is inserted into the zoom lens 10 or the zoom lens 10 and the teleconverter 20. At this time, the distance D between the insertion portion front side 51 and the insertion portion rear side 52 constituting the position correction optical system 50 is as shown in Table 13 below.

  FIG. 30 shows the performance of the zoom lens 10 when the object distance is infinite with the focal length of 10.3 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 2.60 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 2.66 mm.

  FIG. 31 shows the performance of the zoom lens 10 with the focal length 533.5 mm on the most telephoto side and the infinite object distance. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 3.38 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 3.57 mm.

  FIG. 32 shows the performance of the zoom lens 10 when the object distance is 5000 mm with the widest angle of 10.3 mm. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 2.60 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 2.67 mm.

  FIG. 33 shows the performance when the object distance is 5000 mm on the most telephoto side of the zoom lens 10. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 3.92 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 4.17 mm.

  FIG. 34 shows the performance of the zoom lens 10 in a state where the teleconverter 20 is inserted in a state where the object distance is infinite on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 3.93 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D to 4.59 mm.

  FIG. 35 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in a state where the object distance is infinite on the most telephoto side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 6.94 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 8.15 mm.

  FIG. 36 shows the performance of the zoom lens 10 with the teleconverter 20 inserted in the state where the object distance is 5000 mm on the widest angle side. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is apparent from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 3.94 mm. It is clear from (c) that the image position shift at the wavelength of 960 nm is corrected by setting the distance D to 4.59 mm.

  FIG. 37 shows the performance in a state where the teleconverter 20 is inserted in the state where the object distance is 5000 mm on the most telephoto side of the zoom lens 10. When the visible wavelength reference wavelength is 590 nm, it can be confirmed from (a) that the image position at the wavelength of 880 nm and the wavelength of 960 nm is at a position that is more positive than the image position in the visible range. It is clear from (b) that the image position shift at the wavelength of 880 nm is corrected by inserting the image position correcting optical system 50 and setting the distance D to 8.84 mm. Further, it is clear from (c) that the deviation of the image position at the wavelength of 960 nm is corrected by setting the distance D to 10.26 mm.

  Table 13 summarizes the above. In Table 13, 10 indicates a state in which the teleconverter 20 is not inserted into the zoom lens 10 in the lens system 1 according to the fourth embodiment, and 10 + 20 indicates that the teleconverter 20 is inserted into the zoom lens 10 in the lens system 1 according to the fourth embodiment. Each state is shown.

  As described above, the present invention inserts an image position correction optical system having a simple configuration into a high-magnification zoom lens system used in the visible range, and enables adjustment of the distance between the groups. By adjusting the shift of the image position, it is possible to focus on the wavelength in the near infrared region. In such a lens system that adds an optical system to a zoom lens used in the visible range, if there is an insertion space even in an existing lens system, an image position correcting optical system is inserted and applied to a wavelength in the near infrared range. be able to.

It is explanatory drawing which shows schematic structure of the lens system which concerns on this invention (Example 1). 2 is an explanatory diagram illustrating a configuration of an image position correcting optical system in Embodiment 1. FIG. FIG. 6 is a spherical aberration diagram showing performance in a state where the object distance is infinite in a state where the focal length on the widest angle side of the zoom lens in Example 1 is 10.3 mm. FIG. 7 is a spherical aberration diagram illustrating performance in a state where the object distance is infinite in a state where the focal length is 533.5 mm on the most telephoto side of the zoom lens according to the first exemplary embodiment. FIG. 6 is a spherical aberration diagram illustrating performance in a state where the object distance is 5000 mm and the zoom lens according to the first exemplary embodiment is 10.3 mm on the widest side. FIG. 6 is a spherical aberration diagram illustrating performance in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens according to the first exemplary embodiment. FIG. 7 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is infinite on the widest angle side of the zoom lens in Example 1; FIG. 6 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in an infinite object distance state on the most telephoto side of the zoom lens in Example 1; FIG. 6 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the widest angle side of the zoom lens in Example 1; FIG. 6 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens in Example 1; 6 is an explanatory diagram illustrating a configuration of an image position correcting optical system in Embodiment 2. FIG. FIG. 12 is a spherical aberration diagram showing performance in a state where the object distance is infinite in a state where the focal length on the widest angle side of the zoom lens in Example 2 is 10.3 mm. FIG. 10 is a spherical aberration diagram illustrating performance in a state where the object distance is infinite in a state where the focal length is 533.5 mm on the most telephoto side of the zoom lens according to the second exemplary embodiment. FIG. 10 is a spherical aberration diagram illustrating performance when the zoom lens in Example 2 is 10.3 mm on the widest-angle side and the object distance is 5000 mm. FIG. 10 is a spherical aberration diagram illustrating performance in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens according to the second exemplary embodiment. FIG. 12 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is infinite on the widest angle side of the zoom lens in Example 2. FIG. 10 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in an infinite object distance state on the most telephoto side of the zoom lens in Example 2. FIG. 10 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the widest angle side of the zoom lens in Example 2; FIG. 10 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens in Example 2. 10 is an explanatory diagram illustrating a configuration of an image position correcting optical system in Embodiment 3. FIG. FIG. 10 is a spherical aberration diagram showing performance in a state where the object distance is infinite in a state where the focal length on the widest angle side of the zoom lens in Example 3 is 10.3 mm. FIG. 10 is a spherical aberration diagram illustrating performance in a state where the object distance is infinite in a state where the focal length is 533.5 mm on the most telephoto side of the zoom lens according to the third exemplary embodiment. FIG. 10 is a spherical aberration diagram illustrating performance when the zoom lens in Example 3 is 10.3 mm on the widest angle side and the object distance is 5000 mm. FIG. 10 is a spherical aberration diagram illustrating performance in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens in Example 3; FIG. 11 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is infinite on the widest angle side of the zoom lens in Example 3; FIG. 11 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in an infinite object distance state on the most telephoto side of the zoom lens in Example 3; FIG. 11 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the widest angle side of the zoom lens in Example 3; FIG. 11 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens in Example 3; FIG. 10 is an explanatory diagram illustrating a configuration of an image position correcting optical system according to a fourth embodiment. FIG. 10 is a spherical aberration diagram showing performance in a state where the object distance is infinite in a state where the focal length on the widest angle side of the zoom lens in Example 4 is 10.3 mm. FIG. 10 is a spherical aberration diagram illustrating performance in a state where the object distance is infinite in a state where the focal length is 533.5 mm on the most telephoto side of the zoom lens in Example 4; FIG. 10 is a spherical aberration diagram illustrating performance in a state where the zoom lens in Example 4 is 10.3 mm at the widest-angle side and the object distance is 5000 mm. FIG. 12 is a spherical aberration diagram showing performance in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens in Example 4; FIG. 12 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is infinite on the widest angle side of the zoom lens in Example 4; FIG. 11 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in an infinite object distance state on the most telephoto side of the zoom lens in Example 4; FIG. 12 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the widest angle side of the zoom lens in Example 4; FIG. 10 is a spherical aberration diagram showing performance in a state where a teleconverter is inserted in a state where the object distance is 5000 mm on the most telephoto side of the zoom lens in Example 4;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens system 10 Zoom lens 11 Object side fixed group 11A Focus group 12 First movement group 13 Second movement group 14 Image plane side fixed group 20 Teleconverter (magnification optical system)
DESCRIPTION OF SYMBOLS 30 Image position correction | amendment optical system 31 Insertion part front side 32 Insertion part rear side 40 Image position correction optical system 41 Insertion part front side 42 Insertion part rear side 50 Image position correction optical system 51 Insertion part front side 52 Insertion part rear side IMG Image surface FP Filter

Claims (1)

A focusing lens group positioned closest to the object side, a zooming lens group that is positioned closer to the image plane side than the focusing lens and moves linearly according to zooming, and an image plane side of the zooming lens group And a zoom lens having a correction system lens group that moves in a curve according to zooming, and an imaging system lens group that is positioned on the image plane side of the correction system lens group, from the visible range to the near infrared range It is a lens system that can shoot at a wavelength and has a single image plane,
Consists of two groups consisting of a teleconverter inserted and removed between the lens groups constituting the imaging system lens group and a group having different positive and negative powers, and is inserted closer to the image plane than the imaging system lens group. Image position correcting optical system ,
The two groups of the image position correcting optical system are any of an order from the image plane side in the order of the fixed group and the moving group, a moving group, an order in the fixed group, or an order in the moving group and the moving group. The one in the order is chosen,
The distance between the two groups of the image position correction optical system is adjusted according to changes in zooming, focusing, adjustment (switching) of the imaging wavelength range, and various optical conditions that occur when the teleconverter is inserted, and imaging is performed in the visible range. A lens system that enables photographing in the near-infrared region while maintaining the same distance between the position of the imaging system lens group and the image plane at the time .

Images