JP5867270B2 - Anti-vibration infrared optical system and infrared imaging device - Google Patents

Description

The present invention relates to a vibration-proof infrared optical system and an infrared imaging device.

  In recent years, various optical systems and image pickup apparatuses having an image stabilization function have been disclosed. For example, in a front teleconverter having an anti-vibration function described in Patent Document 1, three sheets are bonded to a concave lens group of a converter lens while suppressing various aberrations while ensuring an afocal magnification of 1.9 times or more. Or, a lens group consisting of two bonded lenses and one single lens is adopted, and the anti-vibration function is realized by moving the bonded concave lens group as an anti-vibration lens group perpendicular to the optical axis. doing.

JP 2002-82367 A JP 2007-264191 A

  However, since the optical system of Patent Document 1 performs zooming by inserting and removing the converter lens, it cannot have an anti-vibration function in a short focal length state where the converter lens is not mounted. Further, when the anti-vibration lens group is shifted in a direction perpendicular to the optical axis, there is a possibility that a tilt due to a manufacturing error may occur, and the image may be deteriorated during the anti-vibration. Furthermore, the amount of image movement that can be corrected, which is determined by the maximum amount of movement of the anti-vibration lens group, is as small as about 0.16 mm (about 0.13 ° in terms of optical axis correction angle (see Example 1)). It may not be possible to deal with vibrations with large amplitude.

  In addition to the above problems, the optical system of Patent Document 1 is described only for a general visible optical system, and is an infrared mounted on an infrared imaging device that captures a subject that cannot be seen with the naked eye in the dark. It cannot be applied to optical systems.

  By the way, the infrared imaging device removes the influence of unnecessary infrared rays (for example, self-radiation of the lens barrel) emitted from other than the subject by the infrared detector, and therefore, between the infrared optical system and the infrared detector, A cold shield with an aperture that allows the infrared light collected by the external optical system to pass through is placed to block unnecessary light from the surroundings (side and oblique) of the detection surface, and this cold shield and infrared detector Is cooled to a low temperature (almost liquid nitrogen temperature) to remove as much infrared rays as possible.

  The aperture of the cold shield is designed so that the position and size (exit pupil diameter) of the exit pupil of the infrared optical system coincide with each other. is called. Satisfying this "aperture-matched state" is that the infrared detector can efficiently suppress unnecessary infrared light other than the subject of the infrared optical system, and can take in only the infrared light of the subject. Therefore, it is a necessary condition.

According to a first aspect illustrating the present invention, an anti-vibration infrared optical system comprising a converter lens and an infrared imaging optical system arranged in order from the object side, the converter lens being along the optical axis. It is composed of two sets of positive lens groups having positive refractive power, and an intermediate image is formed between these two sets of positive lens groups, with a rotation center axis orthogonal to the optical axis as the center. It is possible to switch the function as a teleconverter and the function as a wide converter by rotating the entire converter lens in the reverse direction, and swinging the converter lens around the rotation center axis Thus, a vibration-proof infrared optical system capable of performing image blur correction is provided.

According to a second aspect exemplifying the present invention, an image is formed through the image stabilization infrared optical system according to any one of claims 1 to 6 and the image stabilization infrared optical system. There is provided an infrared imaging device comprising an infrared detector that captures a subject image .

According to a third aspect exemplifying the present invention, the image stabilization infrared optical system according to claim 5 or 6 and a subject image formed through the image stabilization infrared optical system are captured. An infrared detector that moves, an elevation mirror rotation drive unit that causes the elevation mirror to oscillate about the oscillation axis, an elevation angle operation unit that is operated when changing the elevation angle of the visual axis, and the elevation angle operation There is provided an infrared imaging device comprising: an elevation angle control unit that performs drive control of the elevation mirror rotation drive unit according to the operation content of the unit .

It is a lens block diagram of the image stabilization infrared optical system which concerns on 1st Example, and shows the reference | standard state (rotation angle (DELTA) (theta) = 0 degree of a converter lens) which has not performed image stabilization correction | amendment. In addition, a tele state and a wide state are shown in order from the top in the figure. It is a lens block diagram of the image stabilization infrared optical system which concerns on 1st Example, and shows the state which is performing image stabilization correction | amendment (rotation angle (DELTA) (theta) = 1 degree of a converter lens). In addition, a tele state and a wide state are shown in order from the top in the figure. FIG. 6 is a lateral aberration diagram in the reference state (rotational angle Δθ = 0 ° of the converter lens) of the vibration-proof infrared optical system according to the first example. In the figure, the telephoto state is shown on the left side and the wide state is shown on the right side. FIG. 6 is a lateral aberration diagram in a state where the image stabilization correction of the image stabilization infrared optical system according to Example 1 is being performed (converter lens rotation angle Δθ = 1 °). In the figure, the telephoto state is shown on the left side and the wide state is shown on the right side. It is a lens block diagram of the image stabilization infrared optical system which concerns on 2nd Example, and shows the reference | standard state (rotation angle (DELTA) (theta) = 0 degree of a converter lens) which is not performing image stabilization correction | amendment. In addition, a tele state and a wide state are shown in order from the top in the figure. It is a lens block diagram of the image stabilization infrared optical system which concerns on 2nd Example, and shows the state which is performing the image stabilization correction | amendment (rotation angle (DELTA) (theta) = 0.5 degree of a converter lens). In addition, a tele state and a wide state are shown in order from the top in the figure. It is a lateral aberration diagram of the reference state (rotational angle Δθ = 0 ° of the converter lens) of the image stabilization infrared optical system according to the second example. In the figure, the telephoto state is shown on the left side and the wide state is shown on the right side. FIG. 10 is a lateral aberration diagram in a state in which image stabilization is performed by the image stabilization infrared optical system according to Example 2 (rotation angle Δθ = 0.5 ° of the converter lens). In the figure, the telephoto state is shown on the left side and the wide state is shown on the right side. It is a lens block diagram of the vibration isolating infrared optical system which concerns on 3rd Example, and shows the reference | standard state (rotation angle (DELTA) (theta) = 0 degree of a converter lens) which has not carried out anti-shake correction. In addition, a tele state and a wide state are shown in order from the top in the figure. It is a lens block diagram of the vibration isolating infrared optical system which concerns on 3rd Example, and shows the state which is performing the image stabilization correction | amendment (rotation angle (DELTA) (theta) = 1 degree of a converter lens). In addition, a tele state and a wide state are shown in order from the top in the figure. It is a lateral aberration diagram of the reference state (rotational angle Δθ = 0 ° of the converter lens) of the image stabilization infrared optical system according to the third example. In the figure, the telephoto state is shown on the left side and the wide state is shown on the right side. FIG. 10 is a lateral aberration diagram in a state in which image stabilization is performed by the image stabilization infrared optical system according to Example 3 (rotation angle Δθ = 1 ° of the converter lens). In the figure, the telephoto state is shown on the left side and the wide state is shown on the right side. It is a schematic block diagram of the infrared imaging device with which the anti-vibration infrared optical system which concerns on this embodiment is hold | maintained by the biaxial gimbal mechanism. It is a lens block diagram of the vibration proof infrared optical system which concerns on 4th Example. In addition, in order from the left side in the figure, a telescopic state with an elevation angle of 40 °, a telescopic state with a depression angle of 40 °, a wide state with an elevation angle of 40 °, and a wide state with a depression angle of 40 ° are shown. It is a lens block diagram of the vibration proof infrared optical system which concerns on 5th Example. In addition, in order from the left side in the figure, a telescopic state with an elevation angle of 40 °, a telescopic state with a depression angle of 40 °, a wide state with an elevation angle of 40 °, and a wide state with a depression angle of 40 ° are shown. It is a schematic block diagram of the infrared imaging device which concerns on this embodiment.

  Hereinafter, embodiments will be described with reference to the drawings. As shown in FIGS. 1 and 2, the vibration-proof infrared optical system according to the present embodiment includes a converter lens CL and an infrared imaging optical system LG arranged in order from the object side. Two sets of positive lens groups GF and GR having positive refractive power (in FIG. 1 and FIG. 2, corresponding to GF1 and GR1) are arranged along the axis, and between these two sets of positive lens groups GF and GR. In this configuration, an intermediate image is formed, and the entire converter lens CL is rotated 180 ° around the rotation center axis O orthogonal to the optical axis and arranged in the opposite direction, thereby functioning as a teleconverter and a wide converter. The image blur correction can be performed by swinging the converter lens CL about the rotation center axis O (rotating at a minute angle Δθ). And it has a capacity configuration.

In this embodiment, when the converter lens CL is to function as a teleconverter, it is made to function as a wide converter so that the front group GF and the rear group GR are arranged in this order from the object side (see the optical path diagram in the upper stage of FIG. 1). In this case, the lens arrangement can be switched by rotating the entire lens system so that the rear group GR and the front group GF are arranged in this order from the object side (see the optical path diagram in the lower part of FIG. 1). Yes.

The state of FIG. 1 is a reference state where the image stabilization correction is not performed (the rotation angle Δθ = 0 ° of the converter lens CL), and the state of FIG. 2 is the state where the image stabilization correction is performed at the rotation angle Δθ = 1 °. is there. At this time, when the converter lens CL functions as a teleconverter (hereinafter also referred to as “tele state”) and when it functions as a wide converter (hereinafter also referred to as “wide state”), Even if the rotation angle Δθ is the same, the actually corrected angle Δω is different. Assuming that the correction angle in the tele state is Δω _T and the correction angle in the wide state is Δω _W , these are the focal length of the front group GF constituting the converter lens CL is f _F, and the focal length of the rear group GR is f _R can be expressed by the following equations (A) and (B) using Δθ and the rotation angle to be oscillated.

  The correction amount Δy on the image plane can be expressed by the following equation (C), where f is the focal length of the entire optical system.

  In such a vibration-proof infrared optical system according to this embodiment, it is preferable that the following conditional expression (1) is satisfied.

但し、ｆ_F：テレコンバーター状態において物体側に位置する、前群ＧＦの焦点距離、
ｆ_R：テレコンバーター状態において像側に位置する、後群ＧＲの焦点距離。

Where f _{F is} the focal length of the front group GF located on the object side in the teleconverter state,
f _R : focal length of the rear group GR located on the image side in the teleconverter state.

When the upper limit of conditional expression (1) is exceeded, the afocal magnification (= f _F / f _R ) of the converter lens CL becomes too large, the length on the optical axis of the converter lens CL becomes too long, and the lens diameter is too large. Problems arise such that the lens becomes too large and it becomes difficult to correct aberrations of the lens.

  In order to ensure the effect of the present embodiment, it is preferable to set the upper limit of conditional expression (1) to 3.5. As a result, the afocal magnification, the total length of the converter lens CL, the aberration generated during the image stabilization correction, and the balance of these three can be kept better.

In the image stabilization infrared optical system according to the present embodiment, the two positive lens groups constituting the converter lens CL, that is, the front group GF and the rear group GR each have at least one positive lens and one negative lens. The positive lens and the negative lens are preferably made of optical materials having different dispersions. With this configuration, the converter lens CL is a lens system in which various aberrations including chromatic aberration are well corrected.

  In the vibration-proof infrared optical system according to the present embodiment, as shown in FIG. 13, the converter lens CL is independent of each other about two rotation center axes X and Y that form 90 degrees with respect to each other when viewed from the optical axis direction. Thus, the entire lens system may be rotated. In FIG. 13, with respect to the converter lens CL (CL1 to CL3) and the infrared imaging optical system LG (LG1 to LG3) according to any one of the first to third embodiments described later, the image plane An infrared detector S that captures a subject image formed by the infrared imaging optical system LG through the arranged anti-vibration infrared optical system is provided, and the lens is held by X and Y 2 while holding the converter lens CL. The infrared imaging device 1 provided with the biaxial gimbal mechanism Gb which can rotate on a shaft is illustrated.

  In this way, in the converter lens CL that can rotate biaxially, the correction directions of the image blur due to the swinging around the rotation center axes X and Y are 90 degrees. Therefore, according to the anti-vibration infrared optical system configured as shown in FIG. 13, an arbitrary two-dimensional image can be obtained by independently determining the minute angular rotation amounts of the rotation center axes X and Y of the converter lens CL. Blur correction can be performed. Note that when the entire converter lens CL is rotated by 180 ° for zooming, it may be rotated about the X axis or about the Y axis.

  Hereinafter, each example according to the present embodiment will be described with reference to the drawings and tables.

  Table 1 shows the refractive indexes of germanium, silicon, and zinc sulfide used as optical materials for lenses constituting the vibration-proof infrared optical system in each example. In Table 1, the refractive index for infrared light having a wavelength of 3 to 5 μm (corresponding to the first and second embodiments) and a wavelength of 8 to 12 μm (corresponding to the third embodiment) is shown.

(Table 1)
<Refractive index of optical material>
Infrared wavelength
3μm 4μm 5μm 8μm 10μm 12μm
Silicon 3.432338 3.425406 3.422272
Germanium 4.044976 4.024610 4.015388 4.005260 4.003073 4.002073
Zinc sulfide − − − 2.222809 2.200164 2.170071

Tables 2 to 7 and Table 8 below show lens data according to the first to third examples and the fifth example. In these tables, f is the focal length of the entire optical system, f _F is the focal length of the front group GF of the converter lens CL, f _R is the focal length of the rear group GR of the converter lens CL, and f _L is The focal length of the infrared imaging optical system LG, 2y represents the image circle diameter, φ represents the entrance pupil diameter, and L _CL represents the total length of the converter lens CL. Further, the surface number is the order of the optical surfaces from the object side along the direction in which the light beam travels, R and r are the radii of curvature of each optical surface, and D is the next optical surface (or image surface) from each optical surface. The surface interval which is the distance on the optical axis is shown. “∞” in the fields of the curvature radii R and r indicates a plane or an aperture, and (aperture AS) indicates an aperture stop AS.

Hereinafter, in all the specification values, the listed focal lengths f, f _F , f _R , f _L , the radius of curvature R, r, the surface interval D, and other lengths are generally “ “mm” is used, but the optical system is not limited to this because the same optical performance can be obtained even if the optical system is proportionally enlarged or reduced. Further, the unit is not limited to “mm”, and other appropriate units can be used.

  The explanation of the table so far is common to all the embodiments, and the explanation below is omitted.

(First embodiment)
1st Example is described using FIGS. 1-4, Table 2, and Table 3. FIG. The anti-vibration infrared optical system according to the first example has a converter lens CL (CL1) disposed on the object side of the infrared imaging optical system LG (LG1) as shown in FIG. Converter lens CL1 includes a front group GF1 having a positive refractive power and a rear group GR1 having a positive refractive power, which are arranged in order along the optical axis in the tele state.

  The front group GF1 includes a positive meniscus lens LF11 and a biconcave lens LF12 arranged in order along the optical axis from the object side in the tele state. The rear group GR1 includes a biconcave lens LR11 and a biconvex lens LR12 that are arranged in order along the optical axis from the object side in the tele state.

  In this embodiment, in order to satisfactorily correct chromatic aberration, the optical material constituting the converter lens CL1 is designed by using two kinds of materials having different dispersions that transmit infrared rays. Specifically, silicon was adopted as the optical material for each of the positive meniscus lens LF11 of the front group GF1, germanium for the biconcave lens LF12, germanium for the biconcave lens LR11 of the rear group GR1, and silicon for the biconvex lens LR12. See Table 1 for refractive index).

  The infrared imaging optical system LG1 includes a positive meniscus lens L11, a negative meniscus lens L12, and a biconvex lens L13 that are arranged in order from the object side along the optical axis. In the present embodiment, silicon is used for the positive meniscus lens L11, germanium is used for the negative meniscus lens L12, and silicon is used for the biconvex lens L13 as optical materials for the lenses constituting the infrared imaging optical system LG1.

  An aperture stop AS (made of germanium) is provided between the infrared imaging optical system LG1 and the image plane I. The image plane I is provided with an infrared detector (not shown) that captures a subject image formed by the infrared imaging optical system LG1 via the converter lens CL1. In both cases of FIG. 1 and FIG. 2, the position of the exit pupil of the optical system and the position of the aperture stop AS coincide with each other, and the aperture is aligned.

  In the anti-vibration infrared optical system of the first embodiment having the above-described configuration, the entire converter lens CL1 is rotated and disposed in the opposite direction around the rotation center axis O orthogonal to the optical axis, and functions as a teleconverter and a wide converter. The function can be switched. For example, when functioning as a teleconverter, the front group GF1 and the rear group GR1 are arranged in this order from the object side (see the optical path diagram in the upper part of FIG. 1). The lens arrangement is switched by rotating the entire converter lens CL1 around the rotation center axis O so that the groups GR1 and the front group GF1 are arranged in this order (see the optical path diagram in the lower part of FIG. 1).

  Further, the image stabilizing infrared optical system of the first embodiment is configured to be able to perform image blur correction by swinging the entire converter lens CL1 around the rotation center axis O. Specifically, in the first embodiment, as shown in FIG. 2, the entire converter lens CL1 is swung at a rotation angle Δθ = 1 ° to perform image stabilization correction.

  Table 2 shows lens data when the image stabilization infrared optical system of the first example is in the tele state, and Table 3 shows lens data when the image stabilization infrared optical system of the first example is in the wide state. . However, since the configuration after the infrared imaging optical system LG1 does not change in the tele state or the wide state, the lens data after the infrared imaging optical system LG1 is not shown in Table 3. The surface numbers 1 to 17 in Table 2 correspond to the optical surfaces having the curvature radii R1 to R17 shown in the upper optical path diagram of FIG. The surface numbers 1 to 9 in Table 3 correspond to the optical surfaces having the curvature radii r1 to r9 shown in the lower optical path diagram of FIG.

(Table 2)
Lens data of anti-vibration infrared optical system of the first embodiment (telephoto state)
Use wavelength: Wavelength 3-5mm (reference wavelength 4mm)
f = 120, f _F = 125.0, f _R = 62.5, f _L = 60
2y = 16, φ = 30, L _CL = 167

Surface number R D Optical material
(Front group GF1) 1 79.8726 8.000 Silicon
2 227.0599 15.500
3 -3118.8633 3.500 Germanium
4 151.9918 55.000
(Rotation center axis O) 5 ∞ 65.000
(Rear group GR1) 6 -395.3668 4.000 Germanium
7 190.3014 4.000
8 1377.8380 12.000 Silicon
9 -75.7284 20.000
(Infrared imaging optical system LG1) 10 30.4347 6.000 Silicon
11 48.6179 9.000
12 118.2056 2.000 Germanium
13 26.4846 11.000
14 311.8124 3.000 Silicon
15 -73.3875 5.000
(Aperture stop AS) 16 ∞ 1.000 Germanium
17 ∞ 30.000

(Table 3)
Lens data of the vibration-proof infrared optical system of the first embodiment (wide state)
Use wavelength: Wavelength 3-5mm (reference wavelength 4mm)
f = 30, f _F = 125.0, f _R = 62.5
2y = 16, φ = 7.5, L _CL = 167

Surface number r D Optical material
(Rear group GR1) 1 75.7284 12.000 Silicon
2 -1377.8380 4.000
3 -190.3014 4.000 Germanium
4 395.3668 65.000
(Rotation center axis O) 5 ∞ 55.000
(Front group GF1) 6 -151.9918 3.500 Germanium
7 3118.8633 15.500
8 -227.0599 8.000 Silicon
9 -79.8726 20.000

From the data in Table 2 and Table 3, it can be seen that f _F / f _R = 2 <5 is satisfied in the image stabilizing infrared optical system of the first example, and the conditional expression (1) is satisfied. Therefore, in the vibration-proof infrared optical system according to the first example, the converter lens CL1 functions sufficiently as an afocal converter lens, and has an afocal magnification, a length on the optical axis, a lens diameter, and the like. It turns out that it is set appropriately.

From the data in Tables 2 and 3, the equations (A) and (B), in the first embodiment, the correction angle in the tele state is Δω _T = 1.5 °, and the correction angle in the wide state is Δω _W = 3.0. °. From the equation (C), the correction amount on the image surface in the tele state is Δy _T = 3.14 mm, and the correction amount on the image surface in the wide state is Δy _W = 1.57 mm.

  FIG. 3 is a lateral aberration diagram in a reference state (rotation angle Δθ = 0 ° of the converter lens CL1) in which the image stabilization correction of the image stabilization infrared optical system according to the first example is not performed. The tele state is shown on the right and the wide state is shown. FIG. 4 is a lateral aberration diagram of the image stabilization infrared optical system according to the first example during image stabilization correction (rotation angle Δθ = 1 ° of the converter lens CL1). Shows the wide state. As can be seen from FIGS. 3 and 4, the anti-vibration infrared optical system according to the first example is in a state where no anti-vibration correction is performed (FIG. 3) and a state where the anti-vibration correction is performed (FIG. 4). Even if these are compared, the optical system has very little change in aberration. As a result, it is possible to provide an image with almost no deterioration even with a relatively large angular eccentricity of the converter lens CL1 with a rotation angle Δθ = 1 °. It can be realized by the mechanism.

(Second embodiment)
A second embodiment will be described with reference to FIGS. 5 to 8 and Tables 4 and 5. FIG. The overall configuration of the second embodiment is substantially the same as that of the first embodiment.

  The anti-vibration infrared optical system according to the second example has a converter lens CL (CL2) disposed on the object side of the infrared imaging optical system LG (LG2) as shown in FIG. Converter lens CL2 has a front group GF2 having a positive refractive power and a rear group GR2 having a positive refractive power, which are arranged in order along the optical axis in the tele state.

  The front group GF2 includes a positive meniscus lens LF21 and a negative meniscus lens LF22 arranged in order along the optical axis from the object side in the tele state. The rear group GR2 includes a negative meniscus lens LR21 and a biconvex lens LR22 arranged in order along the optical axis from the object side in the tele state.

  In this embodiment, in order to satisfactorily correct chromatic aberration, the optical material constituting the converter lens CL2 is designed by using two kinds of materials having different dispersions that transmit infrared rays. Specifically, silicon was used as the optical material for the positive meniscus lens LF21 of the front group GF2, germanium for the negative meniscus lens LF22, germanium for the negative meniscus lens LR21 of the rear group GR2, and silicon for the biconvex lens LR22. (See Table 1 for each refractive index).

  The infrared imaging optical system LG2 includes a positive meniscus lens L21, a negative meniscus lens L22, and a biconvex lens L23 arranged in order from the object side along the optical axis. In this embodiment, silicon is used for the positive meniscus lens L21, germanium is used for the negative meniscus lens L22, and silicon is used for the biconvex lens L23 as optical materials for the lenses constituting the infrared imaging optical system LG2.

  An aperture stop AS (made of germanium) is provided between the infrared imaging optical system LG2 and the image plane I. The image plane I is provided with an infrared detector (not shown) that captures a subject image formed by the infrared imaging optical system LG2 via the converter lens CL2. In both cases of FIG. 5 and FIG. 6, the position of the exit pupil of the optical system and the position of the aperture stop AS coincide with each other, and aperture matching is achieved.

  In the anti-vibration infrared optical system of the second embodiment having the above-described configuration, the entire converter lens CL2 is rotated and arranged in the opposite direction around the rotation center axis O orthogonal to the optical axis, and functions as a teleconverter and a wide converter. The function can be switched. For example, when functioning as a teleconverter, the front group GF2 and the rear group GR2 are arranged in this order from the object side (see the optical path diagram in the upper part of FIG. 5). The lens arrangement is switched by rotating the entire converter lens CL2 around the rotation center axis O so that the groups GR2 and the front group GF2 are arranged in this order (see the optical path diagram in the lower part of FIG. 5).

  In addition, the image stabilizing infrared optical system of the second embodiment is configured to be able to perform image blur correction by swinging the entire converter lens CL2 around the rotation center axis O. Specifically, in the second embodiment, as shown in FIG. 6, the entire converter lens CL2 is swung at the rotation angle Δθ = 0.5 ° to perform the image stabilization correction.

  Table 4 shows lens data when the image stabilization infrared optical system of the second embodiment is in the tele state. Table 5 shows lens data when the image stabilization infrared optical system of the second embodiment is in the wide state. Indicates. However, since the configuration after the infrared imaging optical system LG2 is the same regardless of whether it is in the tele state or the wide state, the lens data after the infrared imaging optical system LG2 is not shown in Table 5. The surface numbers 1 to 17 in Table 4 correspond to the optical surfaces having the curvature radii R1 to R17 shown in the upper optical path diagram of FIG. Surface numbers 1 to 9 in Table 5 correspond to the optical surfaces having the radii of curvature r1 to r9 shown in the lower optical path diagram of FIG.

(Table 4)
Lens data of anti-vibration infrared optical system of the second embodiment (telephoto state)
Use wavelength: Wavelength 3-5mm (reference wavelength 4mm)
f = 180, f _F = 175.2, f _R = 58.4, f _L = 60
2y = 16, φ = 45, L _CL = 217

Surface number R D Optical material
(Front group GF2) 1 146.0611 8.000 Silicon
2 447.7985 16.500
3 1609.5856 3.500 Germanium
4 322.6095 80.500
(Rotation center axis O) 5 ∞ 99.500
(Rear group GR2) 6 979.4904 4.000 Germanium
7 136.5106 3.000
8 255.5940 13.000 Silicon
9 -100.9966 20.000
(Infrared imaging optical system LG2) 10 30.4347 6.000 Silicon
11 48.6179 9.000
12 118.2056 2.000 Germanium
13 26.4846 11.000
14 311.8124 3.000 Silicon
15 -73.3875 5.000
(Aperture stop AS) 16 ∞ 1.000 Germanium
17 ∞ 30.000

(Table 5)
Lens data of the anti-vibration infrared optical system of the second embodiment (wide state)
Use wavelength: Wavelength 3-5mm (reference wavelength 4mm)
f = 20, f _F = 175.2, f _R = 58.4
2y = 16, φ = 5.0, L _CL = 217

Surface number r D Optical material
(Rear group GR2) 1 100.9966 13.000 Silicon
2 -255.5940 3.000
3 -136.5106 4.000 Germanium
4 -979.4904 99.500
(Rotation center axis O) 5 ∞ 80.500
(Front group GF2) 6 -322.6095 3.500 Germanium
7 -1609.5856 16.500
8 -447.7985 8.000 Silicon
9 -146.0611 -217.000

From the data in Table 4 and Table 5, it can be seen that f _F / f _R = 3 <5 is satisfied in the anti-vibration infrared optical system of the second example, and the conditional expression (1) is satisfied. Therefore, in the vibration-proof infrared optical system according to the second example, the converter lens CL2 functions sufficiently as an afocal converter lens, and has an afocal magnification, a length on the optical axis, a lens diameter, and the like. It turns out that it is set appropriately.

From the data in Tables 4 and 5, the equations (A) and (B), in the second embodiment, the correction angle in the tele state is Δω _T = 0.67 °, and the correction angle in the wide state is Δω _W = 2.0. °. From the equation (C), the correction amount on the image plane in the tele state is Δy _T = 2.10 mm, and the correction amount on the image plane in the wide state is Δy _W = 0.70 mm.

  FIG. 7 is a lateral aberration diagram in a reference state (rotation angle Δθ = 0 ° of the converter lens CL2) in which the image stabilization correction of the image stabilization infrared optical system according to Example 2 is not performed. The tele state is shown on the right and the wide state is shown. FIG. 8 is a lateral aberration diagram at the time of image stabilization correction (rotation angle Δθ = 0.5 ° of the converter lens CL2) of the image stabilization infrared optical system according to the second example. Shows the wide state. As can be seen from FIGS. 7 and 8, in the image stabilization infrared optical system according to the second example, the state where the image stabilization correction is not performed (FIG. 7) and the state where the image stabilization correction is performed (FIG. 8). Even if these are compared, the optical system has very little change in aberration. As a result, it is possible to provide an image with almost no deterioration even with a relatively large angular eccentricity of the converter lens CL2 of the rotation angle Δθ = 0.5 °, and the same driving for the rotation zooming and the image stabilization. It can be realized by the mechanism.

As described so far, the overall configuration of the second embodiment is substantially the same as that of the first embodiment, and the photographing lens LG1 and the F value are completely the same. However, the afocal magnification (= f _F / f _R ) of the converter lens CL2 of the second embodiment is 3 times larger than the afocal magnification (= 2 times) of the first embodiment. For this reason, the change of the focal length at the time of rotation zooming is as large as 9 times. However, the length L _CL on the optical axis of the converter lens CL2 becomes longer, and the converter lens CL2 is corrected at the time of image stabilization. The amount of aberration caused by tilting increases. That is, the upper limit value of the conditional expression (1) needs to be set in consideration of the balance between the afocal magnification, the total length of the converter lens, the amount of aberration that occurs during image stabilization correction, and these three. In the present embodiment, as described above, less than 3.5 is derived as a more preferable upper limit value of conditional expression (1).

(Third embodiment)
A third embodiment will be described with reference to FIGS. 9 to 12 and Tables 6 and 7. FIG. As shown in FIG. 9, the image stabilization infrared optical system according to the third example includes a converter lens CL (CL3) disposed on the object side of the infrared imaging optical system LG (LG3). Converter lens CL3 has a front group GF3 having a positive refractive power and a rear group GR3 having a positive refractive power, which are arranged in order along the optical axis in the tele state.

  The front group GF3 includes a positive meniscus lens LF31 and a negative meniscus lens LF32 arranged in order along the optical axis from the object side in the tele state. The rear group GR3 includes a negative meniscus lens LR31 and a positive meniscus lens LR32 arranged in order from the object side along the optical axis in the tele state.

  In this embodiment, in order to satisfactorily correct the chromatic aberration, the optical material constituting the converter lens CL3 is designed using two kinds of materials having different dispersions that transmit infrared rays. Specifically, germanium is used for the positive meniscus lens LF31 of the front group GF3, zinc sulfide is used for the negative meniscus lens LF32, zinc sulfide is used for the negative meniscus lens LR31 of the rear group GR3, and germanium is used for the positive meniscus lens LR32. (Refer to Table 1 for each refractive index).

  The infrared imaging optical system LG3 includes a positive meniscus lens L31, a biconcave lens L32, and a positive meniscus lens L33, which are arranged in order from the object side along the optical axis. In this embodiment, germanium is used for the positive meniscus lens L31, germanium is used for the biconcave lens L32, and germanium is used for the positive meniscus lens L33 as the optical material of the lens constituting the infrared imaging optical system LG3.

  An aperture stop AS (made of germanium) is provided between the infrared imaging optical system LG3 and the image plane I. The image plane I is provided with an infrared detector (not shown) that captures a subject image formed by the infrared imaging optical system LG3 via the converter lens CL3. In both cases of FIGS. 9 and 10, the position of the exit pupil of the optical system and the position of the aperture stop AS coincide with each other, and the aperture alignment is achieved.

  In the anti-vibration infrared optical system of the third embodiment having the above-described configuration, the entire converter lens CL3 is rotated and arranged in the opposite direction around the rotation center axis O orthogonal to the optical axis, and functions as a teleconverter and a wide converter. The function can be switched. For example, when functioning as a teleconverter, the front group GF3 and rear group GR3 are arranged in this order from the object side (see the optical path diagram in the upper part of FIG. 9). The lens arrangement is switched by rotating the entire converter lens CL3 about the rotation center axis O so that the group GR3 and the front group GF3 are arranged in this order (see the optical path diagram in the lower part of FIG. 9).

  In addition, the vibration-proof infrared optical system of the third embodiment is configured such that image blur correction can be performed by swinging the entire converter lens CL3 about the rotation center axis O. Specifically, in the third embodiment, as shown in FIG. 10, the entire converter lens CL3 is swung at a rotation angle Δθ = 1 ° to perform image stabilization correction.

As described so far, the overall configuration of the third embodiment is substantially the same as that of the first embodiment. However, the available infrared wavelength region of the optical system is the far infrared region (8 to 12 mm) in the third embodiment, which is different from the middle infrared region (3 to 5 mm) of the first embodiment. In the third embodiment, the entrance pupil diameter is twice as large as that of the first embodiment. In the third example, the total length of the converter lens CL3 and the total length of the infrared imaging optical system LG3 are also longer than those in the first example.

  Table 6 shows lens data when the image stabilization infrared optical system of the third example is in the tele state. Table 7 shows lens data when the image stabilization infrared optical system of the third example is in the wide state. Indicates. However, since the configuration after the infrared imaging optical system LG3 is the same in the tele state or the wide state, the lens data after the infrared imaging optical system LG3 is not shown in Table 7. The surface numbers 1 to 17 in Table 6 correspond to the optical surfaces having the curvature radii R1 to R17 shown in the upper optical path diagram of FIG. Surface numbers 1 to 9 in Table 7 correspond to the optical surfaces having the curvature radii r1 to r9 shown in the lower optical path diagram of FIG.

(Table 6)
Lens data of the anti-vibration infrared optical system of the third embodiment (tele state)
Use wavelength: 8-12mm (reference wavelength 10mm)
f = 120, f _F = 152.0, f _R = 76.0, f _L = 60
2y = 16, φ = 60, L _CL = 230

Surface number R D Optical material
(Front group GF3) 1 131.7502 7.000 Germanium
2 186.8227 81.500
3 -42.7646 5.500 Zinc sulfide
4 -47.2000 21.000
(Rotation center axis O) 5 ∞ 52.000
(Rear group GR3) 6 39.6939 12.000 Zinc sulfide
7 32.7991 44.000
8 -383.8988 7.000 Germanium
9 -128.6293 20.000
(Infrared imaging optical system LG3) 10 45.2808 6.000 Germanium
11 65.6879 14.500
12 -216.0260 2.500 Germanium
13 63.2687 7.500
14 -447.9834 3.500 Germanium
15 -63.6900 5.000
(Aperture stop AS) 16 ∞ 1.000 Germanium
17 ∞ 30.000

(Table 7)
Lens data of the vibration-proof infrared optical system of the third embodiment (wide state)
Use wavelength: Wavelength 8-12mm (reference wavelength 10mm)
f = 30, f _F = 152.0, f _R = 76.0
2y = 16, φ = 15.0, L _CL = 230

Surface number r D Optical material
(Rear group GR3) 1 128.6293 7.000 Germanium
2 383.8988 44.000
3 -32.7991 12.000 Zinc sulfide
4 -39.6939 52.000
(Rotation center axis O) 5 ∞ 21.000
(Front group GF3) 6 47.2000 5.500 Zinc sulfide
7 42.7646 81.500
8 -186.8227 7.000 Germanium
9 -131.7502 20.000

From the data in Tables 6 and 7, it can be seen that f _F / f _R = 2 <5 is satisfied in the image stabilizing infrared optical system of the third example, and the conditional expression (1) is satisfied. Therefore, in the image stabilization infrared optical system according to the third example, the converter lens CL3 functions sufficiently as an afocal converter lens, and has an afocal magnification, a length on the optical axis, a lens diameter, and the like. It turns out that it is set appropriately.

From the data in Tables 6 and 7 and the equations (A) and (B), in the third embodiment, the correction angle in the tele state is Δω _T = 1.5 °, and the correction angle in the wide state is Δω _W = 3.0. °. From the equation (C), the correction amount on the image surface in the tele state is Δy _T = 3.14 mm, and the correction amount on the image surface in the wide state is Δy _W = 1.57 mm.

  FIG. 11 is a lateral aberration diagram in a reference state (rotation angle Δθ = 0 ° of the converter lens CL3) in which the image stabilization correction of the image stabilization infrared optical system according to Example 3 is not performed. The tele state is shown on the right and the wide state is shown. FIG. 12 is a lateral aberration diagram when the image stabilization infrared optical system according to Example 3 is subjected to image stabilization correction (rotation angle Δθ = 1 ° of converter lens CL3). Shows the wide state. As can be seen from FIGS. 11 and 12, the image stabilization infrared optical system according to the third example has a state in which no image stabilization correction is performed (FIG. 11), and a state in which image stabilization correction is performed (FIG. 12). Even if these are compared, the optical system has very little change in aberration. This makes it possible to provide an image with almost no deterioration even with a relatively large angular eccentricity of the converter lens CL3 with a rotation angle Δθ = 1 °, and the same drive for rotation zooming and image stabilization. It can be realized by the mechanism.

(Fourth embodiment)
A vibration-proof infrared optical system according to the fourth example will be described with reference to FIG. As shown in FIG. 14, the image stabilization infrared optical system according to the fourth example has a rotation center axis O of the converter lens CL (CL1) on the object side of the image stabilization infrared optical system according to the first example. And a plane window P provided on the object side of the elevation mirror M, and the elevation mirror M and the converter lens CL are independently oscillated. By moving the image, it is possible to perform two-dimensional image blur correction. The plane window P is provided to protect the internal anti-vibration infrared optical system including the elevation mirror M. With such a configuration, in the image stabilizing infrared optical system according to the fourth example, the correction direction of the image blur due to the swing is orthogonal between the elevation mirror M and the converter lens CL, and the elevation mirror M and the converter Two-dimensional image blur correction can be performed by arbitrarily determining the swing amount of the lens CL independently of each other. Further, by securing the swinging amount of the elevation mirror M from −20 ° to + 20 °, the visual axis of the optical system can be elevated at an elevation angle of 40 ° and an elevation angle of 40 ° as shown in FIG.

(5th Example)
A vibration-proof infrared optical system according to the fifth example will be described with reference to FIG. The overall configuration of the fifth embodiment is substantially the same as that of the fourth embodiment. However, the plane window P in the fourth embodiment is changed to a substantially spherical window member W centered on the intersection of the swing axis Z of the elevation mirror M and the optical axis, and accordingly, the substantially spherical window is changed. A correction lens Lw is added to return the light beam, which has become a divergent light beam by the refraction action of the member W, to a parallel light beam. Table 8 below shows lens data from the substantially spherical window member W to the elevation mirror M to the correction lens Lw. However, since the configuration of the converter lens CL (CL1) is the same as that of the first embodiment, the description of the lens data is omitted here (see Tables 2 and 3). Surface numbers 1 to 5 in Table 8 correspond to the optical surfaces having the curvature radii R1 to R5 shown in FIG.

(Table 8)
Lens data of anti-vibration infrared optical system of the fifth embodiment Wavelength used: Wavelength 3-5mm (reference wavelength 4mm)
f = 100.6 (telephoto), 25.2 (wide)
2y = 16
φ = 25.14 (telephoto), 6.29 (wide)

Surface number R D Optical material
(Window material W) 1 60.0000 10.000 Silicon
2 50.0000 50.000
(Spine mirror M) 3 ∞ 55.000
(Correction lens Lw) 4 -67.4994 5.000 Silicon
5 -67.3273 20.000
(Subsequent to this, the converter lens CL and thereafter are the same as in the first embodiment)

  In the anti-vibration infrared optical system according to the fifth example, the flat window P in the fourth example is changed to a substantially spherical window member W, thereby reducing the size of the head of the optical system and protecting the member. As the strength is increased. Further, by aligning the center of the substantially spherical window member W with the intersection of the swing axis Z of the elevation mirror M and the optical axis, the astigmatism caused by the change in the visual axis accompanying the swing of the elevation mirror M is eliminated. Occurrence is suppressed. Also in the fifth embodiment, an arbitrary two-dimensional image blur correction can be performed, and the visual axis of the optical system can be raised to an elevation angle of 40 ° and a depression angle of 40 °. The same as in the case of the fourth embodiment.

(Sixth embodiment)
An infrared imaging apparatus according to the sixth embodiment will be described with reference to FIG. As shown in FIG. 16, the infrared imaging device 10 according to the sixth example includes a vibration-proof infrared optical system according to the first example, that is, a converter lens CL (CL1) and an infrared imaging optical system LG (LG1), An infrared detector S that captures a subject image formed by the infrared imaging optical system LG via the converter lens CL; a converter lens rotation driving unit 20 that rotates the entire converter lens CL around the rotation center axis O; It is operated to set the target focal length of the converter lens CL (for example, 120 mm (tele state) shown in the upper optical path diagram of FIG. 1 and 30 mm (wide state) shown in the lower optical path diagram of FIG. 1). The zooming operation unit 30, the zooming control unit 40 that controls the drive of the converter lens rotation driving unit 20 according to the operation content of the zooming operation unit 30, and the swing axis Z The elevation mirror rotation drive unit 50 that swings the elevation mirror M around the heart, the elevation angle operation unit 60 that is operated when changing the elevation angle of the visual axis, and the elevation angle operation unit 60 according to the operation content of the elevation angle operation unit 60. The elevation angle control unit 70 that controls the driving of the mirror rotation driving unit 50, a vibration detection unit 80 that detects the direction and speed of vibration of the infrared imaging optical system LG, and a detection result by the vibration detection unit 80. And the anti-vibration control unit 90 for controlling the drive of the converter lens rotation driving unit 20 and the raising / lowering mirror rotation driving unit 50, and these are held in the lens barrel 100.

In addition, the infrared imaging device 10 includes an infrared imaging optical system LG and an infrared detector S in order to remove the influence of unnecessary infrared rays (for example, self-radiation of the lens barrel) emitted from other than the subject by the infrared detector S. A cold shield 110 having an aperture stop AS that allows infrared light collected by the infrared imaging optical system LG to pass therethrough is disposed, and unnecessary light from around the detection surface (image surface) (side or oblique). The cold shield 110 and the infrared detector S are cooled to a low temperature (substantially liquid nitrogen temperature), and the infrared rays radiated from the cold shield 110 and the infrared detector S are removed as much as possible. The infrared detector S is disposed at a position where infrared rays from a subject or the like are collected by the infrared imaging optical system LG, and has a plurality of imaging elements C on a detection surface (image surface).

  At the time of zooming, in the infrared imaging apparatus 10, when a zooming signal of a target focal length is transmitted from the zooming operation unit 30 by being operated by a photographer, the zooming control unit 40 uses the zooming signal based on the zooming signal. The rotation angle of the converter lens CL necessary for obtaining the value is calculated, and the converter lens rotation drive unit 20 is driven and controlled based on the calculation result. The converter lens CL is driven by the converter lens rotation drive unit 20 as necessary, and is rotated about the rotation center axis O at the rotation angle to switch the lens arrangement, thereby performing desired zooming.

  When the visual axis is elevated, in the infrared imaging device 10, when the target elevation angle is transmitted from the elevation angle operation unit 60 when operated by the photographer, the elevation angle control unit 70 obtains the elevation angle from the elevation angle signal. The swing angle of the elevation mirror M necessary for this is calculated, and the elevation mirror rotation drive unit 50 is driven and controlled based on the calculation result. The raising / lowering mirror M is driven by the raising / lowering mirror rotation drive unit 50 as necessary, and is swung around the swinging axis Z at the swinging angle, so as to be lifted and raised at a desired angle.

  At the time of image stabilization, the vibration detection unit 60 detects the amount of vibration (for example, the rotation angle and speed) of the lens barrel 100, and the image stabilization control unit 90 does not blur the subject image with the infrared detector S from this amount of vibration. Therefore, necessary rotation angles and speeds of the converter lens CL and the elevation mirror M are calculated, and the converter lens rotation drive unit 20 and the elevation mirror rotation drive unit 50 are driven and controlled based on the calculation results. The converter lens CL and the elevation mirror M are driven by the converter lens rotation drive unit 20 and the elevation mirror rotation drive unit 50, respectively, as necessary, and swing around the rotation center axis O and the oscillation axis Z at the rotation angle and speed. To correct image blur.

  In order to make the present invention easy to understand, the configuration requirements of the embodiment have been described, but it goes without saying that the present invention is not limited to this.

CL (CL1 to CL3) Converter lens GF (GF1 to GF3) Front group GR (GR1 to GR3) Rear group LG (LG1 to LG3) Infrared imaging optical system O Rotation center axis AS Aperture stop I Image plane S Infrared detector Z Swing Moving axis M Lifting mirror P Plane window W Substantially spherical window member Lw Correction lens 1,10 Infrared imaging device 20 Converter lens rotation driving unit 30 Zooming operation unit 40 Zooming control unit 50 Lifting mirror rotation driving unit 60 Lifting angle operation unit 70 Elevation angle control unit 80 Vibration detection unit 90 Anti-vibration control unit 100 Lens barrel

Claims (12)

An anti-vibration infrared optical system comprising a converter lens and an infrared imaging optical system, arranged in order from the object side,
The converter lens is
It consists of two sets of positive lens groups having positive refractive power arranged along the optical axis, and an intermediate image is formed between these two sets of positive lens groups.
By rotating the entire converter lens around the rotation center axis orthogonal to the optical axis and arranging it in the reverse direction, it is possible to switch the function as a teleconverter and the function as a wide converter,
An anti-vibration infrared optical system capable of performing image blur correction by swinging the converter lens about the rotation center axis. The two sets of positive lens groups have at least one positive lens and one negative lens,
The anti-vibration infrared optical system according to claim 1, wherein the positive lens and the negative lens are made of optical materials having different dispersions. The vibration-proof infrared optical system according to claim 1 or 2, wherein the following conditional expression is satisfied.

However,
f _F : the focal length of the positive lens group located on the object side in the teleconverter state,
f _R : focal length of the positive lens group located on the image side in the teleconverter state.   The converter lens can be rotated about the rotation center axis, and the converter lens can be rotated about a second rotation center axis orthogonal to both the rotation center axis and the optical axis. The anti-vibration infrared optical system according to any one of claims 1 to 3, further comprising a biaxial gimbal mechanism. On the object side of the converter lens, an elevation mirror that is swingable about a swing axis that is orthogonal to the rotation center axis of the converter lens,
The two-dimensional image blur correction can be performed by independently swinging the elevation mirror and the converter lens, according to any one of claims 1 to 3. The vibration-proof infrared optical system described. A substantially spherical window member provided on the object side of the elevation mirror, the center of which is the intersection of the swing axis of the elevation mirror and the optical axis;
A correction lens that is provided between the elevation mirror and the converter lens, and converts the incident light beam that has passed through the window member and the elevation mirror in turn into a substantially parallel light beam and guides it to the converter lens. The vibration-proof infrared optical system according to claim 5. The vibration-proof infrared optical system according to any one of claims 1 to 6,
An infrared imaging apparatus, comprising: an infrared detector that captures a subject image formed through the vibration-proof infrared optical system. A rotation drive unit that rotates the entire converter lens around the rotation center axis;
A scaling operation unit that is operated when switching a function as a teleconverter and a function as a wide converter,
The infrared imaging apparatus according to claim 7, further comprising: a magnification change control unit that performs drive control of the rotation drive unit according to an operation content of the magnification change operation unit. A vibration detector for detecting the direction and speed of vibration of the infrared imaging optical system;
The infrared imaging apparatus according to claim 8 , further comprising an image stabilization control unit that performs drive control of the rotation drive unit based on a detection result by the vibration detection unit. The vibration-proof infrared optical system according to claim 5 or 6,
An infrared detector that captures a subject image formed via the anti-vibration infrared optical system;
A raising / lowering mirror rotation drive unit that causes the elevation mirror to oscillate about the oscillation axis;
An elevation angle operation unit operated when changing the elevation angle of the visual axis;
An infrared imaging apparatus comprising: an elevation angle control unit that performs drive control of the elevation mirror rotation drive unit according to the operation content of the elevation angle operation unit. A rotation drive unit that rotates the entire converter lens around the rotation center axis;
A scaling operation unit that is operated when switching a function as a teleconverter and a function as a wide converter,
The infrared imaging apparatus according to claim 10, further comprising: a magnification change control unit that performs drive control of the rotation drive unit according to an operation content of the magnification change operation unit. A vibration detector for detecting the direction and speed of vibration of the infrared imaging optical system;
The infrared imaging device according to claim 11 , further comprising: an anti-vibration control unit that performs drive control of the rotation driving unit and the elevation mirror rotation driving unit based on a detection result by the vibration detection unit.

Images