WO2016006486A1 - 対物光学系 - Google Patents
対物光学系 Download PDFInfo
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- WO2016006486A1 WO2016006486A1 PCT/JP2015/068619 JP2015068619W WO2016006486A1 WO 2016006486 A1 WO2016006486 A1 WO 2016006486A1 JP 2015068619 W JP2015068619 W JP 2015068619W WO 2016006486 A1 WO2016006486 A1 WO 2016006486A1
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- objective optical
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/12—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only
- G02B9/14—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only arranged + - +
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- 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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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/04—Reversed telephoto objectives
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/24—Optical objectives specially designed for the purposes specified below for reproducing or copying at short object distances
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
- G02B23/2407—Optical details
- G02B23/2423—Optical details of the distal end
- G02B23/243—Objectives for endoscopes
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0025—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for optical correction, e.g. distorsion, aberration
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/005—Diaphragms
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/12—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only
- G02B9/14—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only arranged + - +
- G02B9/24—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only arranged + - + two of the components having compound lenses
- G02B9/26—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having three components only arranged + - + two of the components having compound lenses the front and rear components having compound lenses
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B9/00—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or -
- G02B9/64—Optical objectives characterised both by the number of the components and their arrangements according to their sign, i.e. + or - having more than six components
Definitions
- the present invention relates to an objective optical system, and relates to an optical system having a focusing function, and more particularly, to an endoscope objective lens capable of performing close-up observation and other photographing lenses such as a small consumer camera.
- a general endoscope objective lens has a wide depth of field of approximately 5 to 100 mm on the object side.
- An endoscope equipped with such an endoscope objective lens mainly provides an image using a solid-state imaging device such as a CCD.
- endoscopes are increasing the number of CCD pixels, that is, increasing the number of CCD pixels.
- an endoscope using a high-pixel CCD has a narrow depth of field as compared with a conventional endoscope. This is because it is necessary to reduce the Fno (F number) of the endoscope objective lens in order to avoid image quality deterioration due to light diffraction, and when the CCD becomes large due to the increase in the number of pixels, the endoscope objective lens. The main reason is that it is necessary to increase the focal length.
- the endoscope objective lens may have a focusing function. For this reason, the need for an endoscope objective lens having a focusing function is increasing.
- An endoscope objective lens having a focusing function is required to be able to be used in the same manner as a conventional endoscope objective lens. For this reason, an endoscope objective lens having a focusing function is required to have an observation angle of view that does not change when focusing.
- Patent Documents 1 to 4 There is an objective lens (objective optical system) disclosed in Patent Documents 1 to 4 as an objective lens having a small focusing angle and a focusing function.
- the objective lens of Patent Document 1 is composed of two groups of negative and positive
- the objective lens of Patent Document 4 is composed of three groups of negative, positive and positive. Both objective lenses are configured to perform focusing by moving the second group.
- Patent Document 2 and Patent Document 3 disclose an objective lens composed of two groups of positive and positive.
- Patent Documents 5 to 7 there are objective lenses disclosed in Patent Documents 5 to 7 as magnifying endoscope objective lenses that are capable of focusing on an object point at a closer distance. These magnifying endoscope objective lenses are configured by three groups of positive, negative, and positive, and are configured to perform focusing by moving the negative second group. Further, Patent Document 8 discloses an optical system that is configured by three groups of negative, positive, and negative, and the positive second group moves to perform focusing.
- Patent Document 1 or Patent Document 2 The objective lens described in Patent Document 1 or Patent Document 2 is hardly a wide angle and has a narrow field of view during observation. For this reason, it is difficult to perform in-vivo screening for finding a lesioned part or performing a treatment on the lesioned part.
- the objective lens described in Patent Document 3 has a large variation in the image plane during focusing, and the optical performance is not sufficient.
- the objective lens described in Patent Document 4 is an example of an optical system that is optimal for focusing.
- the Fno of this objective lens is relatively large, about 6-8. For this reason, there exists a fault which cannot respond to the image pick-up element with higher pixel.
- the objective lenses described in Patent Documents 5 to 8 have a wide range of object points that can be focused and can be observed closer to the object, so that the magnification during closest observation is large. Therefore, these objective lenses are suitable for performing magnified observation. However, these objective lenses have a large change in the angle of view during focusing.
- these objective lenses are wide-angle during normal observation, but are extremely narrow-angle during close-up observation. For this reason, difficulty arises in the workability
- the normal observation refers to the observation of a long distance object point
- the close observation refers to the observation of a short distance object point.
- the present invention has been made in view of such a problem, has a small change in the angle of view during focusing, has a sufficient depth of field at each object point distance, and is a high pixel imaging device.
- the object is to provide a high-performance and bright objective optical system.
- One aspect of the present invention includes, in order from the object side, a positive first group, a negative second group, and a positive third group, and performs focusing by moving the second group. Is composed of, in order from the object side, a negative lens, a positive lens or a cemented lens, and a positive lens, and the third group includes a positive lens and a cemented lens of a positive lens and a negative lens. This is an objective optical system.
- One embodiment of the present invention includes, in order from the object side, a positive first group, a negative second group, and a positive third group, and the second group is a meniscus lens having a convex surface facing the object side.
- the objective optical system is characterized in that focusing is performed by moving on the optical axis, and the following conditional expression (1) is satisfied. 0.12 ⁇ d 2g /f ⁇ 1.02 (1) here, d 2g is the amount of movement of the second group, f is the focal length of the entire objective optical system in the normal observation state, It is.
- the objective optical system according to an embodiment of the present invention has a small change in the angle of view during focusing, has a sufficient depth of field at each object point distance, and has a high performance corresponding to a high pixel imaging device. There is an effect that a bright objective optical system can be provided.
- FIG. 1A is a cross-sectional view in a normal observation state
- FIG. 4 is an aberration diagram showing spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in Example 1.
- SA spherical aberration
- AS astigmatism
- DT distortion
- CC lateral chromatic aberration
- FIG. 6 is an aberration diagram showing spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in Example 2. It is a figure which shows the cross-sectional structure of the objective optical system which concerns on Example 3 of this invention, (a) is sectional drawing in a normal observation state, (b) is sectional drawing in a close-up observation state.
- FIG. 6 is an aberration diagram showing spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in Example 3.
- FIG. 7 is an aberration diagram showing spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in Example 4.
- SA spherical aberration
- AS astigmatism
- DT distortion
- CC lateral chromatic aberration
- FIG. 10 is an aberration diagram showing spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in Example 5.
- the objective optical system according to the embodiment includes, in order from the object side, a positive first group, a negative second group, and a positive third group.
- FIG. 1 is a cross-sectional view showing the overall configuration of the objective optical system according to the first embodiment and the objective optical system according to the second embodiment.
- the objective optical system includes, in order from the object side, a first group G1 having positive power (refractive power), an aperture stop S, a second group G2 having negative power, The third group G3 having the following power is provided.
- the first group G1 includes, in order from the object side, a negative lens, a positive lens or a cemented lens, and a positive lens.
- the third group G3 includes a positive lens and a cemented lens of a positive lens and a negative lens.
- the positive first group G1 includes, in order from the object side, a negative first lens L1, a positive second lens L2, and a positive third lens L3. have. Further, focusing is performed by moving the second group G2. Further, as shown in FIG. 1A, the positive third group G3 includes, in order from the object side, a positive fifth lens L5, a negative sixth lens L6, and a positive seventh lens L7. ing. The positive fifth lens L5 and the negative sixth lens L6 are cemented to form a cemented lens CL1.
- the positive first group G1 has a negative first lens L1, a cemented lens CL1, and a positive fourth lens L4 in order from the object side.
- the positive second lens L2 and the negative third lens L3 are cemented to form a cemented lens CL1. Further, focusing is performed by moving the second group G2.
- the positive third group G3 includes, in order from the object side, a positive sixth lens L6, a negative seventh lens L7, and a positive eighth lens L8.
- the positive sixth lens L6 and the negative seventh lens L7 are cemented to form a cemented lens CL2.
- the second group G2 is composed of a meniscus lens having a convex surface directed toward the object side, and performs focusing by moving on the optical axis. 1) is satisfied.
- the second group G2 includes a meniscus lens L4 having a convex surface directed toward the object side.
- the meniscus lens L4 moves on the optical axis to perform focusing.
- the second group G2 includes a meniscus lens L5 having a convex surface directed toward the object side.
- the meniscus lens L5 moves on the optical axis to perform focusing.
- conditional expression (1 ′) 0.22 ⁇ d 2g /f ⁇ 0.94 (1 ′)
- conditional expression (1 ′) By satisfying conditional expression (1 ′), further reduction in error sensitivity and miniaturization of the optical system can be achieved.
- the objective optical system according to the first embodiment and the objective optical system according to the second embodiment (hereinafter referred to as “objective optical system of the present embodiment”) can be configured as follows.
- the aperture stop S is disposed between the first group G1 and the second group G2.
- a first parallel plate F1 is disposed between the negative first lens L1 and the positive second lens L2.
- the first parallel plate F1 is disposed on the image side of the third group G3.
- the first parallel plate F1 can be arranged at an arbitrary position in the objective optical system.
- an imaging element (not shown) may be arranged near the image plane of the objective optical system to constitute the objective optical system and the imaging optical system.
- a parallel flat plate F2 and a cover glass CG are attached to the image sensor to protect the imaging surface.
- the second group G2 has a negative fourth lens L4.
- the negative fourth lens L4 is a negative meniscus lens having a convex surface directed toward the object side.
- the second group G2 is composed of a negative fifth lens L5.
- the lens group to be moved for focusing may move any of a plurality of groups constituting the objective optical system.
- the movable group may be one group or a plurality of groups.
- the mechanical structure can be simplified.
- focusing is performed by moving the second group G2.
- the negative fourth lens L4 moves along the optical axis AX during focusing.
- the negative fifth lens L5 moves along the optical axis AX.
- the objective optical system according to the present embodiment satisfies the following conditional expression (2). 1.8 ⁇ f 1 /f ⁇ 4.2 (2) here, f is the focal length of the entire objective optical system in the normal observation state, f 1 is the focal length of the first group, It is.
- Conditional expression (2) stipulates conditions that contribute to miniaturization and high performance of the objective optical system.
- conditional expression (2) If the lower limit of conditional expression (2) is not reached, the power of the first group G1 will increase. For this reason, it is advantageous for downsizing the optical system, but it is not preferable because the spherical aberration is too under (undercorrected). If the upper limit of conditional expression (2) is exceeded, the total length of the optical system becomes longer. In this case, it is difficult to reduce the size of the optical system, which is not desirable.
- the objective optical system according to the present embodiment satisfies the following conditional expression (3). ⁇ 20 ⁇ f 2 / f ⁇ 5 (3) here, f is the focal length of the entire objective optical system in the normal observation state, f 2 is the focal length of the second group, It is.
- Conditional expression (3) is a conditional expression for appropriately setting the power of the second lens group G2, and defines conditions for suppressing image plane fluctuation during focusing and contributing to downsizing of the optical system. Yes.
- conditional expression (3) If the lower limit value of conditional expression (3) is not reached, the power of the second group G2 becomes small. In this case, the amount of movement of the second group G2 becomes too large, leading to an increase in the size of the optical system. If the upper limit value of conditional expression (3) is exceeded, the variation in field curvature accompanying focusing increases. This is not preferable because a significant difference appears between the image plane position during normal observation and the image plane position during close-up observation.
- the objective optical system according to the present embodiment satisfies the following conditional expression (4). 2 ⁇ f 3 / f ⁇ 5 (4) here, f is the focal length of the entire objective optical system in the normal observation state, f 3 is the focal length of the third group, It is.
- Conditional expression (4) defines conditions that contribute to correction of field curvature.
- conditional expression (4) If the lower limit of conditional expression (4) is not reached, the image plane will fall to the under side. If the upper limit of conditional expression (4) is exceeded, the image plane tilts toward the over side. As described above, if the conditional expression (4) is not satisfied, an image in which the center portion and the peripheral portion of the screen are not in focus is formed, which is not preferable.
- conditional expression (4 ′) 2.7 ⁇ f 3 / f ⁇ 5 (4 ′)
- the image plane in the peripheral part tends to fall to the under side at the position of each near point during normal observation and close-up observation.
- the objective optical system according to the present embodiment satisfies the following conditional expression (5). 0.85 ⁇ f n /f ⁇ 1.15 (5) here, f is the focal length of the entire objective optical system in the normal observation state, f n is the focal length of the entire objective optical system in the close-up observation state, It is.
- the objective optical system of this embodiment is equipped with a focusing mechanism.
- the angle of view change and the magnification change are small so that the observation image is not affected when focusing. Therefore, by satisfying conditional expression (5), the change in the focal length during focusing can be reduced.
- conditional expression (5) 0.95 ⁇ f n /f ⁇ 1.1
- Satisfying conditional expression (5 ′) further increases the effect of reducing the change in the angle of view during focusing.
- the objective optical system according to the present embodiment satisfies the following conditional expression (6).
- f is the focal length of the entire objective optical system in the normal observation state
- D 2 is the thickness of the second lens
- conditional expression (6 ′) 2.2 ⁇ D 2 /f ⁇ 3.2 (6 ′)
- conditional expression (6 ′) Astigmatism and curvature of field can be minimized by satisfying conditional expression (6 ′).
- the objective optical system according to the present embodiment satisfies the following conditional expression (7).
- f 3t is the focal length of the positive single lens in the third group
- f 3p is the focal length of the positive lens in the cemented lens in the third group
- the third group G3 includes a positive lens and a cemented lens of a positive lens and a negative lens.
- the positive single lens mainly contributes to correction of field curvature.
- chromatic aberration can be favorably corrected by providing a cemented lens.
- conditional expression (7) 1.6 ⁇ f 3t / f 3p ⁇ 3.2 (7 ′)
- conditional expression (7 ′) By limiting to conditional expression (7 ′), chromatic aberration correction and field curvature correction can be corrected in a well-balanced manner.
- the objective optical system includes a first lens disposed closest to the object side and a final lens disposed closest to the image side, and satisfies the following conditional expressions (9) and (10): It is desirable to do. 0.74 ⁇ f th /f ⁇ 1.12 (9) 1.02 ⁇ f mh /f ⁇ 1.58 (10) here, f is the focal length of the entire objective optical system in the normal observation state, f th is the maximum diagonal principal ray height on the image side of the final lens, f mh is the maximum diagonal chief ray height on the object side of the first lens, It is.
- Conditional expressions (9) and (10) are conditional expressions for reducing the size of the optical system. By satisfying at least one of the conditional expressions (9) and (10), not only the lens diameter can be reduced, but also the optical performance is advantageous.
- conditional expression (9) If the lower limit value of conditional expression (9) is not reached, the beam height decreases. For this reason, downsizing of the optical system can be achieved. However, the oblique incident angle on the imaging surface increases. As a result, the decrease in the amount of peripheral light becomes remarkable, which is not preferable. If the upper limit value of conditional expression (9) is exceeded, the beam height increases. As a result, the lens diameter is increased, which is not preferable.
- conditional expression (10) If the lower limit value of conditional expression (10) is not reached, the beam height decreases. For this reason, size reduction can be achieved. However, the incident position of the off-axis light beam on the first surface is closer to the optical axis AX. Therefore, it is necessary to place the entrance pupil position in front of the lens system more than necessary. As a result, it is not suitable for an objective optical system of an endoscope that is required to have a wide angle. If the upper limit of conditional expression (10) is exceeded, the light beam height increases. As a result, the lens diameter is increased, which is not preferable.
- the objective optical system according to the present embodiment satisfies the following conditional expression (11).
- r a is the radius of curvature of the most object side surface of the second group
- r b is the radius of curvature of the most image side surface of the second group radius
- the second group G2 is composed of a meniscus lens having a convex surface facing the object side.
- the shape of the lens of the second group G2 approaches the plano-convex shape from the meniscus shape. For this reason, the principal point position of the 2nd group G2 is located relatively ahead. As a result, it is difficult to appropriately secure a space for moving the lens during focusing.
- the objective optical system according to the present embodiment include the first lens disposed closest to the object side and satisfy the following conditional expression (12). here, -2.2 ⁇ f l1 /f ⁇ -0.8 (12) here, f l1 is the focal length of the first lens, f is the focal length of the entire objective optical system in the normal observation state, It is.
- conditional expression (12) When the conditional expression (12) is satisfied, the curvature of field can be appropriately corrected. Furthermore, it is desirable to satisfy conditional expression (12) because an appropriate viewing angle can be secured.
- conditional expression (12) If the lower limit value of conditional expression (12) is not reached, the image surface falls to the under side, which is not preferable. Exceeding the upper limit value of conditional expression (12) is not preferable because the image surface falls to the over side. Further, if the lower limit value of conditional expression (12) is not reached, distortion will be excessively corrected. For this reason, a viewing angle becomes narrow and is unsuitable for screening etc.
- the objective optical system according to the present embodiment preferably satisfies the following conditional expressions (13-1) and (13-2) at the same time.
- ⁇ f is the half angle of view of the normal observation state of the objective optical system
- ⁇ n is the half field angle of the close-up observation state of the objective optical system, It is.
- the objective optical system according to the present embodiment is as wide as possible in order to reduce oversight of a lesioned part during in vivo screening.
- a viewing angle of at least 120 ° or more is desired in all object point regions.
- the viewing angle is 100 ° or more.
- conditional expressions (13-1) and (13-2) By satisfying conditional expressions (13-1) and (13-2) at the same time, the lesioned part can be detected more reliably during in vivo screening.
- the objective optical system according to this embodiment preferably satisfies the following conditional expression (14). 0.8 ⁇ f 23f / f 23n ⁇ 1.2 (14) here, f 23f is the combined focal length of the second group and the third group in the normal observation state, f 23n is the combined focal length of the second group and the third group in the close-up observation state, It is.
- the aperture stop S is disposed on the image side with respect to the first group G1.
- the conditional expression (14) is satisfied, the position of the exit pupil becomes substantially unchanged during focusing even when the position of the aperture stop S is fixed and the lens group on the image side of the aperture stop is movable. Therefore, the angle of light incident on the image sensor can be kept constant. As a result, it is possible to realize an optical system that is not affected by shading during focusing.
- conditional expression (14) If the lower limit value of conditional expression (14) is not reached, the combined focal length of the second group G2 and the third group G3 becomes smaller in the normal observation state. In this case, since the oblique incident angle on the imaging surface becomes large, the loss of light quantity to the imaging device becomes large. Furthermore, it becomes difficult to appropriately ensure the back focus in the entire objective optical system.
- conditional expression (14) If the upper limit value of conditional expression (14) is exceeded, the combined point distance between the second group G2 and the third group G3 in the close-up observation state becomes small. In this case, the change in the amount of peripheral light is increased by switching between the normal observation state and the proximity observation state, which is not preferable.
- conditional expression (14 ′) By satisfying conditional expression (14 ′), an optical system that is not further affected by shading can be realized even during focusing.
- the objective optical system according to the present embodiment satisfies the following conditional expression (15). ⁇ 8 ⁇ f 2 / f 3 ⁇ 2 (15) here, f 2 is the focal length of the second group, f 3 is the focal length of the third group, It is.
- Conditional expression (15) defines conditions for appropriate correction of field curvature.
- the objective optical system according to the present embodiment satisfies the following conditional expression (16). ⁇ 8.2 ⁇ f 2 / f 1 ⁇ 2.8 (16) here, f 1 is the focal length of the first group, f 2 is the focal length of the second group, It is.
- Conditional expression (16) defines conditions for appropriate correction of spherical aberration and axial chromatic aberration.
- conditional expression (16) If the lower limit of conditional expression (16) is not reached, spherical aberration will be overcorrected. Further, the longitudinal chromatic aberration is not preferable because it increases on the minus side in the C line and increases on the plus side in the F line. If the upper limit of conditional expression (16) is exceeded, spherical aberration will be undercorrected. Also, the longitudinal chromatic aberration is not preferable because it increases on the plus side in the C line and increases on the minus side in the F line.
- the imaging apparatus includes the above-described objective optical system and imaging element, and satisfies the following conditional expression (8).
- conditional expression (8) If the lower limit value of conditional expression (8) is not reached, the image pickup device has a large pixel pitch and a small number of pixels. Therefore, even if a high-performance objective optical system can be realized, a high-definition image cannot be obtained. If the upper limit value of conditional expression (8) is exceeded, the pixel pitch is small, and high definition of the image sensor can be achieved.
- the optical system is weak against error sensitivity, that is, the optical performance against the same manufacturing variation. Is not preferred because it tends to deteriorate.
- Example 1 The objective optical system according to Example 1 will be described.
- 2A is a cross-sectional view of the objective optical system according to the present embodiment in a normal observation state (far-distance object point)
- FIG. 2B is a cross-sectional view in a close-up observation state (short-distance object point). is there.
- a positive first group G1, an aperture stop S1, a negative second group G2, and a positive third group G3 are provided. Yes.
- the positive first group G1 includes, in order from the object side, a plano-concave negative first lens L1, a positive second meniscus lens L2 having a convex surface facing the image side, and a negative first lens having a convex surface facing the image side. 3 meniscus lens L3 and positive fourth meniscus lens L4 having a convex surface facing the object side.
- the positive second meniscus lens L2 and the negative third meniscus lens L3 are cemented to form a cemented lens CL1.
- An aperture stop S1 is arranged behind the first group G1 (on the image plane I side).
- the negative second group G2 includes a negative fifth meniscus lens L5 having a convex surface directed toward the object side.
- the negative fifth meniscus lens L5 moves to the image side (image plane I) along the optical axis AX when focusing from the normal observation state (FIG. 2A) to the close observation state (FIG. 2B). To do.
- the positive third group G3 includes a biconvex positive sixth meniscus lens L6, a negative seventh meniscus lens L7 having a convex surface facing the image side, and a biconvex positive eighth lens L8. .
- the positive sixth meniscus lens L6 and the negative seventh meniscus lens L7 are cemented to form a cemented lens CL2.
- a parallel plate F1 is disposed behind the third group G3 (on the image plane I side), and a cover glass CG is attached to the front surface of an image pickup device (not shown).
- a parallel plate F2 is bonded to the entire surface of the cover glass CG.
- Parallel plates F1 and F2 are filters provided with a coating for cutting a specific wavelength, for example, YAG laser 1060 nm, semiconductor laser 810 nm, or infrared region.
- 3A, 3B, 3C, and 3D show spherical aberration (SA), astigmatism (AS), distortion aberration (DT), and lateral chromatic aberration (CC) in the normal observation state of this embodiment. ).
- 3 (e), (f), (g), and (h) show spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in the close-up observation state of this example. ).
- These aberration diagrams show the respective wavelengths of 656.3 nm (C line), 486.1 nm (F line) and 546.1 nm (e line).
- ⁇ indicates a half angle of view.
- the same reference numerals are used for the aberration diagrams.
- Example 2 An objective optical system according to Example 2 will be described.
- 4A is a cross-sectional view of the objective optical system according to the present embodiment in a normal observation state (far-distance object point)
- FIG. 4B is a cross-sectional view in a close-up observation state (short-distance object point). is there.
- a positive first group G1, an aperture stop S1, a negative second group G2, and a positive third group G3 are provided.
- the positive first group G1 includes, in order from the object side, a plano-concave negative first lens L1, a parallel plate F1, a positive second meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens.
- a third lens L3 is included.
- An aperture stop S1 is arranged behind the first group G1 (on the image plane I side).
- the negative second group G2 includes a negative fourth meniscus lens L4 having a convex surface directed toward the object side.
- the negative fourth meniscus lens L4 moves to the image side (image plane I) along the optical axis AX when focusing from the normal observation state (FIG. 4A) to the close observation state (FIG. 4B). To do.
- the positive third group G3 includes a biconvex positive fifth lens L5, a negative sixth meniscus lens L6 having a convex surface facing the image side, and a biconvex positive seventh lens L7.
- the positive fifth lens L5 and the negative sixth meniscus lens L6 are cemented to form a cemented lens CL1.
- a cover glass CG is attached to the front surface of the image sensor (not shown).
- the parallel plate F1 and the parallel plate F2 are filters provided with a coating for cutting a specific wavelength, for example, 1060 nm of a YAG laser, 810 nm of a semiconductor laser, or an infrared region.
- FIGS. 5A, 5B, 5C, and 5D show spherical aberration (SA), astigmatism (AS), distortion aberration (DT), and lateral chromatic aberration (CC) in the normal observation state of this embodiment.
- FIGS. 5E, 5F, 5G, and 5H show spherical aberration (SA), astigmatism (AS), distortion aberration (DT), and lateral chromatic aberration (CC) in the close-up observation state of this example. ).
- Example 3 An objective optical system according to Example 3 will be described.
- 6A is a cross-sectional view of the objective optical system according to the present embodiment in a normal observation state (far-distance object point)
- FIG. 6B is a cross-sectional view in a close-up observation state (short-distance object point). is there.
- a positive first group G1, an aperture stop S1, a negative second group G2, and a positive third group G3 are provided. Yes.
- the positive first group G1 includes, in order from the object side, a plano-concave negative first lens L1, a parallel plate F1, a positive second meniscus lens L2 having a convex surface facing the image side, and a biconvex positive lens.
- a third lens L3 is included.
- An aperture stop S1 is arranged behind the first group G1 (on the image plane I side).
- the negative second group G2 includes a negative fourth meniscus lens L4 having a convex surface directed toward the object side.
- the negative fourth meniscus lens L4 moves to the image side (image plane I) along the optical axis AX when focusing from the normal observation state (FIG. 6A) to the close observation state (FIG. 6B). To do.
- the positive third group G3 includes a biconvex positive fifth lens L5, a biconvex positive sixth lens L6, and a negative seventh meniscus lens L7 having a convex surface facing the image side.
- the positive sixth lens L6 and the negative seventh meniscus lens L7 are cemented to form a cemented lens CL1.
- a parallel plate F1 is disposed behind the first lens L1 (on the image plane I side). Further, a cover glass CG is attached to the front surface of the image pickup device (not shown). In the present embodiment, a parallel plate F2 is bonded to the entire surface of the cover glass CG.
- Parallel plates F1 and F2 are filters provided with a coating for cutting a specific wavelength, for example, YAG laser 1060 nm, semiconductor laser 810 nm, or infrared region.
- FIGS. 7E, 7F, 7G, and 7H show spherical aberration (SA), astigmatism (AS), distortion aberration (DT), and lateral chromatic aberration (CC) in the close-up observation state of this example. ).
- FIG. 8A is a cross-sectional view of the objective optical system according to the present embodiment in a normal observation state (distant object point), and FIG. 8B is a cross-sectional view in a close observation state (short distance object point). is there.
- a positive first group G1, an aperture stop S1, a negative second group G2, and a positive third group G3 are provided in order from the object side. Yes.
- the positive first group G1 includes, in order from the object side, a plano-concave negative first lens L1, a parallel plate F1, a positive second meniscus lens L2 having a convex surface facing the image side, and a convex surface facing the object side.
- a positive third meniscus lens L3 is provided.
- An aperture stop S1 is arranged behind the first group G1 (on the image plane I side).
- the negative second group G2 includes a negative fourth meniscus lens L4 having a convex surface directed toward the object side.
- the negative fourth meniscus lens L4 moves to the image side (image plane I) along the optical axis AX when focusing from the normal observation state (FIG. 8A) to the close observation state (FIG. 8B). To do.
- the positive third group G3 includes a biconvex positive fifth lens L5, a negative sixth meniscus lens L6 having a convex surface facing the image side, and a biconvex positive seventh lens L7.
- the positive fifth lens L5 and the negative sixth meniscus lens L6 are cemented to form a cemented lens CL1.
- a cover glass CG is pasted on the front surface of the image sensor (not shown).
- a parallel plate F2 is bonded to the entire surface of the cover glass CG.
- Parallel plates F1 and F2 are filters provided with a coating for cutting a specific wavelength, for example, YAG laser 1060 nm, semiconductor laser 810 nm, or infrared region.
- Example 5 An objective optical system according to Example 5 will be described.
- 10A is a cross-sectional view of the objective optical system according to the present embodiment in a normal observation state (far-distance object point)
- FIG. 10B is a cross-sectional view in a close-up observation state (short-distance object point). is there.
- a positive first group G1, an aperture stop S1, a negative second group G2, and a positive third group G3 are provided in this order from the object side. Yes.
- the positive first group G1 includes, in order from the object side, a plano-concave negative first lens L1, a parallel plate F1, a positive second meniscus lens L2 having a convex surface facing the image side, and a convex surface facing the object side.
- a negative third meniscus lens L3 directed to the lens and a positive biconvex fourth lens L4 are provided.
- the negative third meniscus lens L3 and the positive fourth lens L4 are cemented to form a cemented lens CL1.
- An aperture stop S1 is arranged behind the first group G1 (on the image plane I side).
- the negative second group G2 includes a negative fifth meniscus lens L5 having a convex surface directed toward the object side.
- the negative fifth meniscus lens L5 moves to the image side (image plane I) along the optical axis AX when focusing from the normal observation state (FIG. 10A) to the close observation state (FIG. 10B). To do.
- the positive third group G3 includes a biconvex positive sixth lens L6, a negative seventh meniscus lens L7 having a convex surface facing the image side, and a biconvex positive eighth lens L8.
- the positive sixth lens L6 and the negative seventh meniscus lens L7 are cemented to form a cemented lens CL2.
- a parallel plate F2 is disposed behind the third group G3 (on the image plane I side).
- a cover glass CG is affixed to the front surface of an image sensor (not shown).
- a parallel plate F3 is bonded to the entire surface of the cover glass CG.
- Parallel plates F1 and F2 are filters provided with a coating for cutting a specific wavelength, for example, YAG laser 1060 nm, semiconductor laser 810 nm, or infrared region.
- 11A, 11B, 11C, and 11D show spherical aberration (SA), astigmatism (AS), distortion aberration (DT), and lateral chromatic aberration (CC) in the normal observation state of this embodiment.
- 11E, 11F, 11G, and 11H show spherical aberration (SA), astigmatism (AS), distortion (DT), and lateral chromatic aberration (CC) in the close-up observation state of this example. ).
- r are the radii of curvature of the lens surfaces
- d is the distance between the lens surfaces
- ne is the refractive index of the e-line of each lens
- ⁇ d is the Abbe number of each lens
- Fno is the F number.
- Table 1 below shows values corresponding to the conditional expressions (1) to (16) in the configuration of each example.
- Table 1 Conditional Example Example 1
- Example 2 Example 3
- Example 4 Example 5 (1) d 2g / f 0.28 0.90 0.31 0.70 0.46 (2) f 1 / f 1.98 3.07 2.11 2.81 2.12 (3) f 2 / f -7.56 -18.19 -7.29 -10.22 -6.39 (4) f 3 / f 3.22 3.38 3.04 3.14 2.86 (5) f n / f 1.03 1.03 1.03 1.06 1.05 (6) D 2 / f 3.01 2.86 2.45 2.84 2.73 (7) f 3t / f 3p 1.75 2.20 2.20 2.56 2.58 (8) (Fno) * (f) / (p * 1000) 1.50 1.44 2.03 2.88 2.80 (9) f th / f 0.90 0.90 0.84 0.99 0.86 (10) f mh / f 1.37 1.30 1.22
- the invention of the following structures is guide
- (Additional item 1) In order from the object side, it is composed of a positive first group, a negative second group, and a positive third group. Focusing is done by moving the second group, The first group includes, in order from the object side, a negative lens, a positive lens or a cemented lens, and a positive lens.
- the third group includes an objective optical system having a positive lens and a cemented lens of a positive lens and a negative lens.
- (Appendix 2) In order from the object side, it is composed of a positive first group, a negative second group, and a positive third group.
- the second group consists of a meniscus lens with a convex surface facing the object side, and performs focusing by moving on the optical axis.
- Additional items 1 to 6, comprising the objective optical system according to any one of 8 to 22 and an image sensor, An image pickup apparatus satisfying the following conditional expression (8): 1.2 ⁇ (Fno) ⁇ (f) / (p ⁇ 1000) ⁇ 3.2 (8) f is the focal length of the entire objective optical system in the normal observation state, Fno is the normal observation F number, p is the pixel pitch in the image sensor, It is.
- the present invention relates to an objective optical system having a focusing function, and more particularly to an imaging objective lens such as an endoscopic objective lens capable of close-up observation and other small consumer cameras.
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Abstract
Description
本発明の一態様は、物体側から順に、正の第1群と、負の第2群と、正の第3群で構成され、第2群を移動することでフォーカシングを行い、第1群は、物体側から順に、負レンズと、正レンズまたは接合レンズと、正レンズで構成され、第3群は、正レンズと、正レンズと負レンズの接合レンズを有していることを特徴とする対物光学系である。
0.12<d2g/f<1.02 (1)
ここで、
d2gは第2群の移動量、
fは通常観察状態の対物光学系全系の焦点距離、
である。
0.12<d2g/f<1.02 (1)
d2gは第2群の移動量、
fは通常観察状態の対物光学系全系の焦点距離、
である。
0.22<d2g/f<0.94 (1´)
1.8<f1/f<4.2 (2)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
f1は第1群の焦点距離、
である。
-20<f2/f<-5 (3)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
f2は第2群の焦点距離、
である。
2<f3/f<5 (4)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
f3は第3群の焦点距離、
である。
2.7<f3/f<5 (4´)
0.85<fn/f<1.15 (5)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
fnは近接観察状態の対物光学系全系の焦点距離、
である。
0.95<fn/f<1.1 (5´)
1.6<D2/f<3.8 (6)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
D2は第2レンズの肉厚、
である。
2.2<D2/f<3.2 (6´)
ここで、
1.2<f3t/f3p<3.6 (7)
f3tは第3群内の正の単レンズの焦点距離、
f3pは第3群内の接合レンズにおける正レンズの焦点距離、
である。
1.6<f3t/f3p<3.2 (7´)
0.74<fth/f<1.12 (9)
1.02<fmh/f<1.58 (10)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
fthは最終レンズの像側面における最大対角主光線高、
fmhは第1レンズの物体側面における最大対角主光線高、
である。
ここで、
raは第2群の最も物体側面の曲率半径、
rbは第2群の最も像側面の曲率半径、
である。
ここで、
-2.2<fl1/f<-0.8 (12)
ここで、
fl1は第1レンズの焦点距離、
fは通常観察状態の対物光学系全系の焦点距離、
である。
-1.8<fl1/f<-1.2 (12´)
ωf>60° (13-1)
ωn>50° (13-2)
ここで、
ωfは対物光学系の通常観察状態の半画角、
ωnは対物光学系の近接観察状態の半画角、
である。
0.8<f23f/f23n<1.2 (14)
ここで、
f23fは通常観察状態での第2群と第3群の合成焦点距離、
f23nは近接観察状態での第2群と第3群の合成焦点距離、
である。
0.9<f23f/f23n<1.0 (14´)
-8<f2/f3<-2 (15)
ここで、
f2は第2群の焦点距離、
f3は第3群の焦点距離、
である。
-8.2<f2/f1<-2.8 (16)
ここで、
f1は第1群の焦点距離、
f2は第2群の焦点距離、
である。
1.2<(Fno)×(f)/(p×1000)<3.2 (8)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
Fnoは通常観察状態のFナンバー、
pは撮像素子における画素ピッチ、
である。
条件式(8)の上限値を上回ると、画素ピッチが小さく、撮像素子の高精細化を図ることができる。ここで、このような撮像素子に対応するよう対物光学系の高性能化を図ると光学系の大型化を招くことに加えて、誤差感度に弱い光学系、即ち同じ製造ばらつきに対して光学性能が劣化しやすくなるため好ましくない。
実施例1に係る対物光学系について説明する。
図2(a)は、本実施例に係る対物光学系の、通常観察状態(遠距離物点)における断面図、図2(b)は、近接観察状態(近距離物点)における断面図である。
図2(a)、(b)に示すように、物体側から順に、正の第1群G1と、明るさ絞りS1と、負の第2群G2と、正の第3群G3を備えている。
図3(e)、(f)、(g)、(h)は、本実施例の近接観察状態における球面収差(SA)、非点収差(AS)、歪曲収差(DT)、倍率色収差(CC)を示す。
実施例2に係る対物光学系について説明する。
図4(a)は、本実施例に係る対物光学系の、通常観察状態(遠距離物点)における断面図、図4(b)は、近接観察状態(近距離物点)における断面図である。
図4(a)、(b)に示すように、物体側から順に、正の第1群G1、明るさ絞りS1、負の第2群G2、正の第3群G3を備えている。
図5(e)、(f)、(g)、(h)は、本実施例の近接観察状態における球面収差(SA)、非点収差(AS)、歪曲収差(DT)、倍率色収差(CC)を示す。
実施例3に係る対物光学系について説明する。
図6(a)は、本実施例に係る対物光学系の、通常観察状態(遠距離物点)における断面図、図6(b)は、近接観察状態(近距離物点)における断面図である。
図6(a)、(b)に示すように、物体側から順に、正の第1群G1と、明るさ絞りS1と、負の第2群G2と、正の第3群G3を備えている。
図7(e)、(f)、(g)、(h)は、本実施例の近接観察状態における球面収差(SA)、非点収差(AS)、歪曲収差(DT)、倍率色収差(CC)を示す。
実施例4に係る対物光学系について説明する。
図8(a)は、本実施例に係る対物光学系の、通常観察状態(遠距離物点)における断面図、図8(b)は、近接観察状態(近距離物点)における断面図である。
図8(a)、(b)に示すように、物体側から順に、正の第1群G1と、明るさ絞りS1と、負の第2群G2と、正の第3群G3を備えている。
実施例5に係る対物光学系について説明する。
図10(a)は、本実施例に係る対物光学系の、通常観察状態(遠距離物点)における断面図、図10(b)は、近接観察状態(近距離物点)における断面図である。
図10(a)、(b)に示すように、物体側から順に、正の第1群G1と、明るさ絞りS1と、負の第2群G2と、正の第3群G3を備えている。
図11(e)、(f)、(g)、(h)は、本実施例の近接観察状態における球面収差(SA)、非点収差(AS)、歪曲収差(DT)、倍率色収差(CC)を示す。
単位 mm
面データ
面番号 r d ne νd
1 ∞ 0.20 1.88815 40.76
2 0.615 0.50
3 -2.775 1.51 1.48915 70.23
4 -1.043 0.25 2.01169 28.27
5 -1.242 0.03
6 1.846 0.33 1.75453 35.33
7 9.075 0.16
8(明るさ絞り) ∞ 可変
9 1.416 0.22 1.88815 40.76
10 0.924 可変
11 2.992 0.86 1.73234 54.68
12 -1.109 0.23 1.93429 18.90
13 -5.338 0.03
14 2.210 0.64 1.53947 74.70
15 -2.120 0.08
16 ∞ 0.30 1.51500 75.00
17 ∞ 0.28
18 ∞ 0.30 1.51825 64.14
19 ∞ 0.30 1.52207 60.00
20(撮像面)
各種データ
パラメータ 通常観察状態 近接観察状態
焦点距離 0.502 0.514
Fno 3.00 3.09
物点距離 12.8 4.28
d8 0.03 0.17
d10 0.44 0.30
撮像素子画素ピッチ p : 0.001 mm
単位 mm
面データ
面番号 r d ne νd
1 ∞ 0.20 1.88815 40.76
2 0.643 0.31
3 ∞ 0.30 1.51500 75.00
4 ∞ 0.14
5 -1.779 1.43 1.48915 70.23
6 -1.291 0.03
7 2.472 0.28 1.75453 35.33
8 -1688.228 0.11
9(明るさ絞り) ∞ 可変
10 1.678 0.22 1.88815 40.76
11 1.304 可変
12 3.908 0.78 1.73234 54.68
13 -1.099 0.19 1.93429 18.90
14 -3.382 0.03
15 1.790 0.54 1.48915 70.23
16 -4.902 0.47
17 ∞ 0.35 1.51825 64.14
18 ∞ 0.40 1.52218 60.00
19(撮像面)
各種データ
パラメータ 通常観察状態 近接観察状態
焦点距離 0.501 0.517
Fno 3.46 3.59
物点距離 12.5 4.2
d9 0.03 0.48
d11 0.73 0.28
撮像素子画素ピッチ p : 0.0012 mm
単位 mm
面データ
面番号 r d ne νd
1 ∞ 0.21 1.88815 40.76
2 0.750 0.48
3 ∞ 0.40 1.52300 65.13
4 ∞ 0.08
5 -6.474 1.67 1.49846 81.54
6 -1.470 0.03
7 4.363 0.41 1.69417 31.07
8 -7.692 0.12
9(明るさ絞り) ∞ 可変
10 2.114 0.28 1.88815 40.76
11 1.340 可変
12 2.160 0.57 1.48915 70.23
13 -7.246 0.02
14 7.155 0.73 1.73234 54.68
15 -1.322 0.25 1.97189 17.47
16 -2.932 0.72
17 ∞ 0.50 1.51825 64.14
18 ∞ 0.50 1.51705 60.00
19(撮像面)
各種データ
パラメータ 通常観察状態 近接観察状態
焦点距離 0.681 0.701
Fno 4.18 4.33
物点距離 16.5 6.04
d9 0.03 0.24
d11 0.85 0.64
撮像素子画素ピッチ p : 0.0014 mm
単位 mm
面データ
面番号 r d ne νd
1 ∞ 0.38 1.88815 40.76
2 1.343 0.86
3 ∞ 0.40 1.52300 65.13
4 ∞ 0.34
5 -4.495 2.83 1.49846 81.54
6 -2.622 0.05
7 3.753 0.72 1.65222 33.79
8 26.231 0.10
9(明るさ絞り) ∞ 可変
10 4.837 0.48 1.58482 40.75
11 2.572 可変
12 4.333 2.02 1.73234 54.68
13 -2.096 0.48 1.93429 18.90
14 -7.265 0.04
15 4.212 1.08 1.49846 81.54
16 -7.951 1.00
17 ∞ 0.50 1.51825 64.14
18 ∞ 0.50 1.50192 60.00
19(撮像面)
各種データ
パラメータ 通常観察状態 近接観察状態
焦点距離 0.997 1.053
Fno 4.62 4.90
物点距離 18.5 6.64
d9 0.22 0.92
d11 1.18 0.48
撮像素子画素ピッチ p : 0.0016 mm
単位 mm
面データ
面番号 r d ne νd
1 ∞ 0.32 1.88815 40.76
2 1.203 0.66
3 ∞ 0.55 1.51825 64.14
4 ∞ 0.17
5 -4.943 2.72 1.48915 70.23
6 -2.267 0.14
7 3.571 0.42 1.85504 23.78
8 2.154 0.51 1.69417 31.07
9 -95.823 0.16
10(明るさ絞り) ∞ 可変
11 4.303 0.41 1.88815 40.76
12 2.336 可変
13 3.958 1.66 1.73234 54.68
14 -1.795 0.37 1.93429 18.90
15 -6.782 0.03
16 11.979 0.78 1.67340 47.23
17 -4.509 0.27
18 ∞ 0.30 1.52300 65.13
19 ∞ 0.79
20 ∞ 0.50 1.51825 64.14
21 ∞ 0.50 1.51705 60.00
22(撮像面)
各種データ
パラメータ 通常観察状態 近接観察状態
焦点距離 0.998 1.051
Fno 5.05 5.37
物点距離 18 5.88
d10 0.31 0.77
d12 0.87 0.41
撮像素子画素ピッチ p : 0.0018 mm
(表1)
条件式 実施例1 実施例2 実施例3 実施例4 実施例5
(1) d2g/f 0.28 0.90 0.31 0.70 0.46
(2) f1/f 1.98 3.07 2.11 2.81 2.12
(3) f2/f -7.56 -18.19 -7.29 -10.22 -6.39
(4) f3/f 3.22 3.38 3.04 3.14 2.86
(5) fn/f 1.03 1.03 1.03 1.06 1.05
(6) D2/f 3.01 2.86 2.45 2.84 2.73
(7) f3t/f3p 1.75 2.20 2.20 2.56 2.58
(8) (Fno)*(f)/(p*1000)
1.50 1.44 2.03 2.88 2.80
(9) fth/f 0.90 0.90 0.84 0.99 0.86
(10) fmh/f 1.37 1.30 1.22 1.45 1.21
(11) |ra-rb|/|ra+rb| 0.21 0.13 0.22 0.31 0.30
(12) fl1/f -1.37 -1.45 -1.24 -1.52 -1.36
(13-1) ωf 79.3 70.2 -78.7 80.5 67.1
(13-2) ωn 71.6 64.4 -70.0 67.0 59.1
(14) f23f/f23n 0.95 0.94 0.95 0.92 0.91
(15) f2/f3 -2.35 -5.38 -2.40 -3.25 -2.23
(16) f2/f1 -3.81 -5.92 -3.45 -3.64 -3.02
なお、これらの実施例から以下の構成の発明が導かれる。
(付記項1)
物体側から順に、正の第1群と、負の第2群と、正の第3群で構成され、
第2群を移動することでフォーカシングを行い、
第1群は、物体側から順に、負レンズと、正レンズまたは接合レンズと、正レンズで構成され、
第3群は、正レンズと、正レンズと負レンズの接合レンズを有していることを特徴とする対物光学系。
物体側から順に、正の第1群と、負の第2群と、正の第3群で構成され、
第2群は物体側に凸面を向けたメニスカスレンズで構成され、光軸上を移動することでフォーカシングを行い、
以下の条件式(1)を満足することを特徴とする対物光学系。
0.12<d2g/f<1.02 (1)
ここで、
d2gは第2群の移動量、
fは通常観察状態の対物光学系全系の焦点距離、
である。
以下の条件式(2)、(3)、(4)のうちのいずれかを満足することを特徴とする付記項1または2に記載の対物光学系。
1.8<f1/f<4.2 (2)
-20<f2/f<-5 (3)
2<f3/f<5 (4)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
f1は第1群の焦点距離、
f2は第2群の焦点距離、
f3は第3群の焦点距離、
である。
以下の条件式(5)を満足することを特徴とする付記項1または2に記載の対物光学系。
0.85<fn/f<1.15 (5)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
fnは近接観察状態の対物光学系全系の焦点距離、
である。
以下の条件式(6)を満足することを特徴とする付記項1または2に記載の対物光学系。
1.6<D2/f<3.8 (6)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
D2は第2レンズの肉厚、
である。
以下の条件式(7)を満足することを特徴とする付記項1または2に記載の対物光学系。
1.2<f3t/f3p<3.6 (7)
ここで、
f3tは第3群内の正の単レンズの焦点距離、
f3pは第3群内の接合レンズにおける正レンズの焦点距離、
である。
最も像側に配置された最終レンズを有し、
以下の条件式(9)を満足することを特徴とする付記項1または2に記載の対物光学系。
0.74<fth/f<1.12 (9)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
fthは最終レンズの像側面における最大対角主光線高、
である。
最も物体側に配置された第1レンズを有し、
以下の条件式(10)を満足することを特徴とする付記項1または2に記載の対物光学系。
1.02<fmh/f<1.58 (10)
ここで、
fは通常観察状態の対物光学系全系の焦点距離、
fmhは第1レンズの物体側面における最大対角主光線高、
である。
第2群は、以下の条件式(11)を満足することを特徴とする付記項1または2に記載の対物光学系。
0.1<|ra-rb|/|ra+rb|<0.4 (11)
ここで、
raは第2群の最も物体側面の曲率半径、
rbは第2群の最も像側面の曲率半径、
である。
最も物体側に配置された第1レンズを有し、
以下の条件式(12)を満足することを特徴とする付記項1または2に記載の対物光学系。
-2.2<fl1/f<-0.8 (12)
ここで、
fl1は第1レンズの焦点距離、
fは通常観察状態の対物光学系全系の焦点距離、
である。
以下の条件式(13-1)、(13-2)を同時に満足することを特徴とする付記項1または2に記載の対物光学系。
ωf>60° (13-1)
ωn>50° (13-2)
ここで、
ωfは通常観察状態の対物光学系の半画角、
ωnは近接観察状態の対物光学系の半画角、
である。
以下の条件式(14)を満足することを特徴とする付記項1または2に記載の対物光学系。
0.8<f23f/f23n<1.2 (14)
ここで、
f23fは通常観察状態での第2群と第3群の合成焦点距離、
f23nは近接観察状態での第2群と第3群の合成焦点距離、
である。
以下の条件式(15)を満足することを特徴とする付記項1または2に記載の対物光学系。
-8<f2/f3<-2 (15)
ここで、
f2は第2群の焦点距離、
f3は第3群の焦点距離、
である。
以下の条件式(16)を満足することを特徴とする付記項1または2に記載の対物光学系。
-8.2<f2/f1<-2.8 (16)
ここで、
f1は第1群の焦点距離、
f2は第2群の焦点距離、
である。
以下の条件式(1´)を満足することを特徴とする付記項2に記載の対物光学系。
0.22<d2g/f<0.94 (1´)
以下の条件式(4´)を満足することを特徴とする付記項3に記載の対物光学系。
2.7<f3/f<5 (4´)
以下の条件式(5´)を満足することを特徴とする付記項4に記載の対物光学系。
0.95<fn/f<1.1 (5´)
以下の条件式(6´)を満足することを特徴とする付記項5に記載の対物光学系。
2.2<D2/f<3.2 (6´)
以下の条件式(7´)を満足することを特徴とする付記項6に記載の対物光学系。
1.6<f3t/f3p<3.2 (7´)
以下の条件式(12´)を満足することを特徴とする付記項11に記載の対物光学系。
-1.8<fl1/f<-1.2 (12´)
以下の条件式(14´)を満足することを特徴とする付記項13に記載の対物光学系。
0.9<f23f/f23n<1.0 (14´)
付記項1から6、8から22のいずれか1項に記載の対物光学系と撮像素子を備え、
以下の条件式(8)を満足することを特徴とする撮像装置。
1.2<(Fno)×(f)/(p×1000)<3.2 (8)
fは通常観察状態の対物光学系全系の焦点距離、
Fnoは通常観察状態のFナンバー、
pは撮像素子における画素ピッチ、
である。
G2 第2群
G3 第3群
L1 負の第1レンズ
L2 正の第2レンズ
L3 正の第3レンズ
L4 負の第4レンズ
L5 正の第5レンズ
L6 負の第6レンズ
L7 正の第7レンズ
S、S1 明るさ絞り
F1、F2、F3 フィルター
CG カバーガラス
Claims (2)
- 物体側から順に、正の第1群と、負の第2群と、正の第3群で構成され、
前記第2群を移動することでフォーカシングを行い、
前記第1群は、物体側から順に、負レンズと、正レンズまたは接合レンズと、正レンズで構成され、
第3群は、正レンズと、正レンズと負レンズの接合レンズを有していることを特徴とする対物光学系。 - 物体側から順に、正の第1群と、負の第2群と、正の第3群で構成され、
前記第2群は、物体側に凸面を向けたメニスカスレンズで構成され、光軸上を移動することでフォーカシングを行い、
以下の条件式(1)を満足することを特徴とする対物光学系。
0.12<d2g/f<1.02 (1)
ここで、
d2gは前記第2群の移動量、
fは通常観察状態の前記対物光学系全系の焦点距離、
である。
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US20160370558A1 (en) | 2016-12-22 |
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