JP2018054914A - Optical system and optical device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system which includes an optical element made of an organic material and offers superior environmental resistance.SOLUTION: An optical system 100 is configured to form an image of an object on a light receiving plane IP, and includes an optical element OE1 made of an organic material, light shielding means MR1 disposed on the object side with respect to the optical element OE1, and an aperture stop. The light shielding means MR1 has a non-circular opening. A distance hp between an optical axis and a point at which one of rays directed to a maximum off-axis image height in the light receiving plane IP that passes through the center of the aperture stop SP passes through the opening of the light shielding means MR1, a maximum distance ha between the optical axis and a point at which a ray heading to an on-axis image height in the light receiving plane IP passes the opening of the light shielding means MR1, and a distance Lr between the light shielding means MR1 and an incident surface of the optical element OE1 on the optical axis satisfy a condition expressed as: 0.020<tan(ha/Lr)/tan(hp/Lr)<0.95.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an optical system having an optical element made of an organic material, and is suitable for optical equipment such as a silver salt film camera, a digital still camera, a video camera, a telescope, binoculars, a projector, and a digital copying machine. It is.

  In recent years, an optical system (photographing optical system) used in an optical apparatus such as a camera is required to be small and light and have high optical performance. Patent Documents 1 and 2 describe optical systems that can satisfactorily correct chromatic aberration while realizing miniaturization by using diffractive optical elements and optical elements having anomalous dispersion characteristics, respectively.

JP 2006-317605 A JP 2010-117472 A

  However, since the optical systems described in Patent Documents 1 and 2 employ an optical element made of an organic material, the optical characteristics and shape of the optical element change when ultraviolet light is incident thereon, and the optical performance is excellent. May not be obtained. In the optical system described in Patent Document 1, an ultraviolet cut coat composed of a multilayer film is provided on the lens closest to the object side. With this configuration, the shielding effect against ultraviolet rays having a large incident angle is small, and the environment resistance is improved. There wasn't always enough.

  An object of the present invention is to realize excellent environmental resistance in an optical system having an optical element made of an organic material.

In order to achieve the above object, an optical system according to one aspect of the present invention is an optical system that forms an image of an object on a light-receiving surface, an optical element made of an organic material, and an object side of the optical element. A non-circular aperture provided in the light-shielding means, and the light-shielding means has a non-circular aperture. The distance between the optical axis and the position where the light beam passing through the center passes through the opening of the light shielding means, and the optical axis between the position where the light beam traveling toward the axial image height on the light receiving surface passes through the opening of the light shielding means and the optical axis. When the maximum distance is ha and the distance on the optical axis between the light shielding means and the incident surface of the optical element is Lr, 0.020 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) ) <0.95 is satisfied.

  ADVANTAGE OF THE INVENTION According to this invention, the outstanding environmental resistance is realizable in the optical system which has an optical element comprised with an organic material.

Sectional drawing in the in-focus state of the object at infinity of the optical system which concerns on Example 1 of this invention Schematic diagram of the light shielding means according to the first embodiment. The figure which shows the transmittance | permeability characteristic of the ultraviolet reflective means based on Example 1 Sectional drawing in the in-focus state of the object at infinity of the optical system which concerns on Example 2 of this invention Schematic diagram of light shielding means according to embodiment 2. Sectional drawing in the in-focus state of the object at infinity of the optical system which concerns on Example 3 of this invention Schematic diagram of light shielding means according to embodiment 3 The perspective view of the optical apparatus which concerns on embodiment of this invention

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. Each drawing may be drawn on a different scale for convenience. Moreover, in each drawing, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  FIG. 1 is a main part schematic diagram (main part cross-sectional view) in a cross section including the optical axis OA of the optical system 100 according to the present embodiment. An optical system 100 according to the present embodiment is an optical system that forms an image on a light receiving surface disposed on an image plane IP, and is an optical element OE1 made of an organic material and closer to the object side than the optical element OE1. The light-shielding means MR1 and the aperture stop SP are disposed. The light shielding means MR1 is provided with a non-circular opening. In the following description, it is assumed that a light beam (parallel light parallel to the optical axis OA) from an object at infinity is incident on the optical system 100.

Here, the distance between the optical axis OA and the position where the light beam passing through the center of the aperture stop SP1 out of the light flux toward the most off-axis image height on the light receiving surface passes through the aperture of the light shielding means MR1 is denoted by hp. Further, the maximum distance between the position at which the light beam toward the on-axis image height on the light receiving surface passes through the opening of the light shielding unit MR1 and the optical axis OA is ha, and the optical surface (incident surface) on the object side of the light shielding unit MR1 and the optical element OE1. Let Lr be the distance on the optical axis OA. At this time, the optical system 100 according to the present embodiment satisfies the following conditional expression (1).
0.020 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) <0.95 (1)

  The optical system 100 according to the present embodiment achieves excellent environmental resistance due to the above configuration. The optical system 100 will be described in detail below.

  The optical element in the present embodiment refers to an optical member that is made of an inorganic material such as glass or an organic material such as plastic (resin) and has a refractive action or a diffractive action. For materials that have substantially no refracting action or diffracting action, such as bonding members (adhesives) for bonding a plurality of optical elements, thin films and coating materials for preventing reflection and improving adhesion, etc. It is not included in the optical element according to the present embodiment.

  In addition, the organic material in the present embodiment indicates a material mainly composed of an organic substance, that is, a material having the highest ratio of the organic substance, and a mixture of a plurality of organic substances or inorganic fine particles dispersed in the organic substance ( Organic compound). For example, as the organic material, acrylic, polycarbonate, polyvinyl carbazole, a mixture thereof, or a mixture of these with other organic or inorganic substances can be employed.

  In addition, the optical surface in this embodiment has shown the part which consists of a continuous curved surface (a spherical surface with a constant curvature radius, or an aspherical surface defined by the same definition formula) in each optical element, and the opening of a light shielding means. , Corresponding to a plane (effective plane) through which an effective ray contributing to image formation passes. That is, in each optical element, in order to facilitate processing or hold by the lens barrel, the margin provided on the outer peripheral portion of the effective surface is the optical surface in the present embodiment even if it is a mirror-finished surface. Does not apply to the face.

  As the optical element OE1 composed of an organic material, a diffractive optical element or a refractive optical element having an optical characteristic (anomalous dispersion characteristic) different from that of a normal glass material is used, so that chromatic aberration can be reduced while achieving miniaturization It becomes possible to correct. However, in general, when an organic material is exposed to ultraviolet rays, the organic material absorbs ultraviolet rays, resulting in polymer chain scission, etc., and the optical properties and shape of the organic material such as refractive index, transmittance, and absorption change. Resulting in. Therefore, in an optical system having an optical element made of an organic material, there is a possibility that the optical performance will fluctuate when ultraviolet rays are incident on the optical element.

  Therefore, in the present embodiment, by providing light shielding means MR1 that shields an area through which an effective light beam that contributes to image formation does not pass on the object side of the optical element OE1, ineffective light rays that do not contribute to image formation are shielded. Yes. As the light shielding means MR1, for example, a member (flare cutter) in which a noncircular opening is provided in a member that is opaque to at least ultraviolet rays can be employed. According to the light shielding means MR1, it becomes possible to shield ultraviolet rays while suppressing an increase in the overall length and weight of the optical system.

  Here, as in the telephoto type optical system, the height of the most peripheral ray (axial beam) of the axial beam is closer to the object side than the aperture stop, and the principal ray (most off-axis beam) of the most off-axis beam is Consider an optical system that is higher than the height. In such an optical system, it is difficult to block the ineffective light beam without blocking the effective light beam by the light blocking means. On the other hand, in an optical system in which the height of the off-axis light beam is higher than the height of the on-axis light beam on the object side of the aperture stop, such as a retrofocus type optical system, the effective light beam is blocked by the light blocking means. Ineffective light rays can be shielded.

  In general, the shape of an imaging surface (light receiving surface) of an imaging element used in an imaging device is a rectangle. For example, the size of the imaging surface of a full-size sensor used in a single-lens reflex camera is vertical × horizontal: 24 mm × 36 mm, and the size of the imaging surface of an APS-C size sensor is vertical × horizontal: 15 mm. × 22.5 mm. When the optical system is applied to an image pickup apparatus, the shape of each optical surface is a circle having a diameter corresponding to the maximum length (diagonal length) of the image pickup surface. In an area higher than the height of the light beam, an area that does not contribute to image formation occurs.

  Therefore, in the optical system 100 according to the present embodiment, the amount of ultraviolet light incident on the optical element OE1 is set by appropriately setting the arrangement of the light shielding means MR1 and the optical element OE1 so as to satisfy the conditional expression (1). Is sufficiently reduced. When the ratio of the angle at which the on-axis light beam is expected to be smaller than the angle at which the object-side off-axis light beam is viewed from the optical element OE1 on the optical axis OA becomes small, the light shielding means MR1 can block the ineffective light beam. . Therefore, by disposing the light shielding means MR1 at a position where the height of the most off-axis light beam is higher than the height of the axial light beam so as to satisfy the conditional expression (1), the ineffective light beam can be sufficiently shielded. It is possible to reduce the amount of ultraviolet light incident on the optical element OE1.

  If the lower limit of conditional expression (1) is surpassed, the height of the on-axis light beam and the most off-axis light beam will be too far apart, so it is necessary to increase the effective diameter of the optical element closest to the object side. 100 becomes large. If the upper limit of conditional expression (1) is exceeded, the height of the on-axis light beam and the most off-axis light beam will be too close, and the area of the optical surface of the optical element OE1 that can be shielded by the light shielding means MR1 will be small. It becomes difficult to obtain a sufficient light shielding effect.

Furthermore, it is more preferable to satisfy the following conditional expressions (1a) to (1d) in order.
0.040 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) <0.92 (1a)
0.060 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) <0.90 (1b)
0.080 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) <0.85 (1c)
0.20 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) <0.80 (1d)

Note that the optical system 100 according to this embodiment desirably satisfies the following conditional expression (2).
0.10 <hp / Lr <1.0 (2)

  Conditional expression (2) shows the arrangement of the light shielding means MR1 for shielding the ultraviolet light incident on the optical element OE1 at a large incident angle by the light shielding means MR1 in the optical system 100. By disposing the light shielding means MR1 sufficiently away from the optical element OE1, it is possible to sufficiently shield ultraviolet rays incident at a large incident angle. At this time, it is preferable to arrange an optical element made of an inorganic material between the light shielding means MR1 and the optical element OE1. Thereby, according to the internal transmittance | permeability of the optical element comprised with an inorganic material, the light quantity of the ultraviolet-ray which reaches | attains optical element OE1 can be reduced.

  If the lower limit of conditional expression (2) is not reached, the distance between the light shielding means MR1 and the optical element OE1 becomes too large, and the optical system 100 may not be sufficiently miniaturized. If the upper limit of conditional expression (2) is exceeded, the angle at which the off-axis light beam passes through the optical element OE1 at the opening of the light shielding unit MR1 on the optical axis OA (the angle of the light shielding unit MR1 viewed from the optical element OE1). The opening angle of the opening becomes too large. As a result, there is a possibility that the ultraviolet light incident on the optical element OE1 at a large incident angle from the object side cannot be sufficiently shielded by the light shielding means MR1.

Furthermore, it is more preferable to satisfy the following conditional expressions (2a) to (2d) in order.
0.15 <hp / Lr <0.90 (2a)
0.24 <hp / Lr <0.80 (2b)
0.28 <hp / Lr <0.70 (2c)
0.32 <hp / Lr <0.60 (2d)

Here, the distance on the optical axis OA between the light shielding means MR1 and the optical surface closest to the object is Lm, and the light beam passing through the center of the aperture stop SP out of the light flux toward the most off-axis image height on the light receiving surface. The distance between the position passing through the optical surface closest to the object in 100 and the optical axis OA is hp0. At this time, it is desirable that the optical system 100 satisfies the following conditional expression (3).
0 ≦ Lm / hp0 <1.0 (3)

  Conditional expression (3) indicates the angle of light rays between the most object-side optical surface in the optical system 100 and the light shielding means MR1. In order to realize an optical system having excellent environmental resistance, it is necessary to sufficiently shield light incident on the optical element OE1 at a large incident angle by the light shielding means MR1. For this purpose, it is necessary to secure a sufficient area in the optical element OE1 that can be shielded by the light shielding means MR1 by arranging the light shielding means MR1 as close to the object side as possible.

  The middle side of the conditional expression (3) is 0 when the light shielding unit MR1 is disposed on the most object side of the optical system 100, and therefore does not become a negative value. When the upper limit of the conditional expression (3) is exceeded, the light shielding means MR1 is arranged away from the object side and is arranged inside the optical system 100 (inner arrangement), and the area where ineffective light rays enter the light shielding means MR1 is small. As a result, it may be difficult to obtain a sufficient light shielding effect.

Furthermore, it is more preferable to satisfy the following conditional expressions (3a) to (3d) in order.
0 ≦ Lm / hp0 <0.95 (3a)
0 ≦ Lm / hp0 <0.90 (3b)
0 ≦ Lm / hp0 <0.85 (3c)
0 ≦ Lm / hp0 <0.80 (3d)

  In the optical system 100, it is desirable not only to shield light rays that enter an area that does not contribute to imaging, but also to shield ultraviolet rays that enter an area that contributes to imaging. As a method therefor, it is conceivable to provide an ultraviolet light shielding means separately from the light shielding means MR1 on the object side of the optical element OE1. Examples of the ultraviolet light shielding means include an absorption type having characteristics of absorbing ultraviolet light (ultraviolet absorption means) and a reflective type reflecting ultraviolet light (ultraviolet reflection means). For example, the ultraviolet absorbing means can be formed of an ultraviolet absorbing material, and the ultraviolet reflecting means can be formed of a multilayer film in which a plurality of dielectric layers are deposited.

  Since the ultraviolet ray absorbing means has no angle dependency of the ultraviolet ray shielding effect, the ultraviolet ray reaching the optical element OE1 can be reduced no matter what angle the ultraviolet ray enters. For example, a lens having a refractive function, that is, a lens made of an ultraviolet absorbing material can be used as the ultraviolet absorbing means. However, since the ultraviolet ray shielding effect of the ultraviolet ray absorbing means depends on the thickness thereof, when the lens-like ultraviolet ray absorbing means is adopted, a uniform ultraviolet ray shielding effect cannot be obtained in the radial direction.

  In addition, since the types of ultraviolet absorbing material are limited, depending on the configuration of the optical system, it may be difficult to obtain good optical performance when a lens-shaped ultraviolet absorbing material is disposed. In addition, when a flat-shaped ultraviolet absorbing means is arranged instead of a lens, it is necessary to arrange a lens separately from that, so the number of optical members increases compared to the case where a lens-shaped ultraviolet absorbing means is arranged, and the optical The total length and weight of the system will increase.

  On the other hand, according to the ultraviolet reflecting means, since it can be used as an antireflection film provided on the optical surface, it is not necessary to separately arrange it in the optical system as a flat filter or increase the number of lenses. Further, according to the ultraviolet reflecting means, since the transmittance characteristic (change in transmittance with respect to the wavelength) can be made steeper than the ultraviolet absorbing means, the influence on the color balance of the entire optical system is reduced, A good ultraviolet light shielding effect can be obtained.

  However, the transmittance characteristic of the ultraviolet reflecting means has an angular dependency that the larger the incident angle between the surface normal of the optical surface provided with the ultraviolet reflecting means and the incident light beam, the shorter the wavelength shifts. There is. Therefore, as the incident angle of the ultraviolet light incident on the ultraviolet reflecting means increases, the ultraviolet light shielding effect decreases.

  Therefore, in the optical system 100 according to the present embodiment, not only the above-described light shielding unit MR1 but also the ultraviolet reflecting unit CU1 is arranged on the object side with respect to the optical element OE1, so that the ultraviolet light incident on the optical element OE1 at a large incident angle. Is sufficiently shielded from light. At this time, since the ultraviolet light incident on the ultraviolet reflection means CU1 at a large incident angle is also shielded by the light shielding means MR1, the influence of the angle dependency of the ultraviolet reflection means CU1 can be reduced, and a good ultraviolet light shielding effect is obtained. It becomes possible.

  The ultraviolet reflecting means CU1 is desirably provided on the optical surface disposed on the object side of the optical element OE1 as in the present embodiment, but may be disposed as an independent member as necessary. Further, it is more preferable that the ultraviolet reflecting means CU1 is provided on an optical surface that is convex toward the object side. According to this, since the incident angle of the off-axis light beam incident on the ultraviolet reflection means CU1 can be reduced, not only the on-axis ultraviolet light but also the off-axis ultraviolet light can be sufficiently shielded.

When the incident angle of the light beam with respect to the ultraviolet reflecting means CU1 is larger than 45 °, the transmission characteristics of the ultraviolet reflecting means CU1 are greatly shifted to the short wavelength side, and the ultraviolet light shielding effect cannot be sufficiently obtained. Therefore, in the cross section including the minimum diameter of the opening of the light shielding means MR1 and the optical axis OA, the maximum incident angle with respect to the ultraviolet reflecting means of the light beam traveling from the opening toward the intersection of the incident surface of the optical element OE1 and the optical axis OA is θcS. In this case, it is desirable to satisfy the following conditional expression (4)
θcS <45 ° (4)

Furthermore, it is more preferable that the following conditional expressions (4a) to (4e) are satisfied in order.
θcS <42 ° (4a)
θcS <40 ° (4b)
θcS <38 ° (4c)
θcS <36 ° (4d)
θcS <34 ° (4e)

  As the ultraviolet reflecting means CU1, in order to obtain a good ultraviolet light shielding effect, it is desirable to use one having a transmittance for light having a wavelength of 360 nm perpendicularly incident on the ultraviolet reflecting means CU1 of 20% or less. More preferably, the transmittance of the ultraviolet reflecting means CU1 may be 15% or less, more preferably 10% or less, with respect to light having a wavelength of 360 nm that is incident vertically.

Further, when the wavelength of the light when the transmittance of the ultraviolet reflecting means CU1 is 50% with respect to the light perpendicularly incident on the ultraviolet reflecting means CU1, the following conditional expression (5) is satisfied. It is desirable.
365 nm ≦ λ50 ≦ 430 nm (5)

By satisfying conditional expression (5), it is possible to maintain good transmittance characteristics (color balance) in the visible light region of the entire optical system 100. Furthermore, it is more preferable to satisfy the following conditional expressions (5a) to (5e) in order.
367 nm ≦ λ50 ≦ 430 nm (5a)
369 nm ≦ λ50 ≦ 420 nm (5b)
371 nm ≦ λ50 ≦ 415 nm (5c)
373 nm ≦ λ50 ≦ 410 nm (5d)
375 nm ≦ λ50 ≦ 405 nm (5e)

In order to keep the color balance of the entire system of the optical system 100 good, it is desirable to make the characteristics of the ultraviolet reflection effect of the ultraviolet reflection means CU1 steep. Specifically, when the transmittance of the ultraviolet reflecting means CU1 is 10% and 90% with respect to the light incident perpendicularly to the ultraviolet reflecting means CU1, the wavelengths of the light are λ10 and λ90, respectively. It is desirable to satisfy the conditional expression (6).
λ90−λ10 ≦ 30 nm (6)

Furthermore, it is more preferable to satisfy the following conditional expressions (6a) to (6d) in order.
λ90−λ10 ≦ 29 nm (6a)
λ90−λ10 ≦ 28 nm (6b)
λ90−λ10 ≦ 26 nm (6c)
λ90−λ10 ≦ 24 nm (6d)

In order to obtain good transmittance characteristics with respect to light in the visible light region, the transmittance of the ultraviolet reflecting means CU1 is desirably 80% or more in the wavelength range of 480 nm to 660 nm. More preferably, the transmittance in the wavelength range of 480 nm to 660 nm of the ultraviolet reflecting means CU1 may be 85% or more, and more preferably 90% or more. In order to obtain the above-described transmittance characteristics, it is preferable that the ultraviolet reflecting means CU1 is composed of a multilayer film containing titanium oxide (particularly TiO ₂ ).

  In general, since the shape of the imaging surface of the imaging element used in the imaging device is a rectangle having an aspect ratio of, for example, 3: 2, 16: 9, or 1: 1, the shape of the opening of the light shielding unit MR1 is imaged. It is desirable to use a rectangle having an aspect ratio substantially equal to the surface. According to this, since the area of the light shielding part of the light shielding means MR1 can be increased, a sufficient light shielding effect can be obtained.

  Here, the rectangle indicates a shape including two pairs of sides that are substantially parallel to each other. In addition to a strict rectangle, at least one of the sides constituting the rectangle is a curved line, a rectangle A substantially rectangular shape such as one obtained by eliminating each vertex is included. For example, a circular light shielding member (opaque member) MC provided with a rectangular opening MO as shown in FIG. 2 may be adopted as the light shielding means MR1. However, when the shape of the opening of the light shielding means MR1 is not a strict rectangle, the direction along the minimum diameter of the opening is the short side direction, and the direction perpendicular to the direction is the long side direction.

  Further, when the shapes of the opening and the light receiving surface of the light shielding unit MR1 are rectangular, the light shielding unit MR1 is arranged so that the short side direction and the long side direction of the opening are aligned with the short side direction and the long side direction of the light receiving surface. It is desirable that they are arranged. According to this, it is possible to effectively shield the area that does not contribute to image formation in the optical system 100.

In the light shielding means MR1, it is desirable that the following conditional expression (7) is satisfied when the circle having the maximum diameter of the opening and the area of the light shielding portion are S0 and Sc, respectively.
0.02 <Sc / S0 <0.5 (7)

  If the lower limit of conditional expression (7) is not reached, the area that can be shielded by the light shielding means MR1 among the areas that do not contribute to image formation in the optical system 100 becomes small, and it may be difficult to obtain a sufficient light shielding effect. Occurs. If the upper limit of conditional expression (7) is exceeded, the area contributing to image formation in the optical system 100 is blocked by the light shielding means MR1, the amount of effective light flux decreases, and the out-of-focus area blur image becomes non-circular. There is a possibility that

Furthermore, it is more preferable to satisfy the following conditional expressions (7a) to (7d) in order.
0.030 <Sc / S0 <0.50 (7a)
0.040 <Sc / S0 <0.50 (7b)
0.050 <Sc / S0 <0.50 (7c)
0.060 <Sc / S0 <0.50 (7d)

  The optical element OE1 according to this embodiment is made of a resin (ultraviolet curable resin) that is cured by irradiation with ultraviolet rays. The ultraviolet curable resin has absorption characteristics with respect to the ultraviolet region such as i-line (365 nm) and h-line (405 nm). Therefore, it is easier to absorb ultraviolet rays than other resin materials, and when exposed to ultraviolet rays. Properties such as refractive index and transmittance are likely to change. A method of adding an additive to the ultraviolet curable resin so that the characteristics are not changed by light in the ultraviolet region is also conceivable. However, in this case, the curability of the ultraviolet curable resin due to ultraviolet rays is reduced, and the optical element OE1 is formed well. It can be difficult to do. Therefore, when the optical element OE1 is made of an ultraviolet curable resin, a particularly great effect of the present invention can be obtained by employing the light shielding unit MR1 and the ultraviolet reflection unit CU1 according to the present embodiment.

  In order to satisfactorily correct chromatic aberration in the optical system 100, when the optical element OE1 is formed using a material having anomalous dispersion characteristics, the thickness of the optical element OE1 in the optical axis direction is sufficiently increased. It is desirable. However, in the optical element OE1, as the thickness in the optical axis direction increases, the change in optical characteristics due to irradiation with ultraviolet rays becomes more significant. Therefore, particularly when the optical element OE1 is thick in the optical axis direction, specifically, when the maximum thickness of the optical element OE1 is 0.2 mm or more, the light shielding unit MR1 and the ultraviolet reflection unit CU1 according to the present embodiment are employed. Is desirable. Further, as the maximum thickness of the optical element OE1 increases in the order of 0.4 mm or more, 0.6 mm or more, and 0.9 mm or more, a remarkable effect can be obtained by the light shielding unit MR1 and the ultraviolet reflection unit CU1.

Further, when the optical element OE1 has a large refractive power in order to correct chromatic aberration satisfactorily in the optical system 100, the deviation ratio of the optical element OE1 increases, and therefore, due to a change in the optical characteristics of the optical element OE1. The effect on optical performance will increase. Therefore, when the refractive powers of the entire optical element OE1 and the optical system 100 are φr and φ, respectively, when the following conditional expression (8) is satisfied, the light shielding means MR1 and the ultraviolet reflection means CU1 have a remarkable effect. Can be obtained.
0.010 <φr / φ (8)

  If the lower limit of conditional expression (8) is not reached, the refractive power of the optical element OE1 becomes sufficiently small, and the deviation ratio in the radial direction of the optical element OE1 becomes sufficiently small, so that the optical characteristics of the optical element OE1 change. However, the effect on the entire system is small and it does not matter. On the other hand, when the conditional expression (8) is satisfied and the optical element OE1 has a large refractive power with respect to the entire system, the influence due to the change in the optical characteristics of the optical element OE1 becomes large. It is particularly desirable to employ MR1 and UV reflection means CU1.

Furthermore, it is more preferable to satisfy the following conditional expressions (8a) to (8d) in order.
0.020 <φr / φ (8a)
0.040 <φr / φ (8b)
0.080 <φr / φ (8c)
0.10 <φr / φ (8d)

When the extinction coefficient of the organic material constituting the optical element OE1 with respect to light having a wavelength of 360 nm is kr, when the following conditional expression (9) is satisfied, the light-shielding means MR1 and the ultraviolet reflection means CU1 have a large effect. Can be obtained.
5.0 × 10 ⁻⁶ <kr (9)

  If the lower limit of conditional expression (9) is not reached, the amount of ultraviolet light absorbed by the organic material constituting the optical element OE1 becomes sufficiently small, and the influence of the ultraviolet light on the optical performance is reduced, so that the light shielding means MR1 and the ultraviolet light reflecting means CU1. The effect of the present invention cannot be obtained.

Furthermore, it is more preferable to satisfy the following conditional expressions (9a) to (9d) in order.
6.0 × 10 ⁻⁶ <kr (9a)
7.0 × 10 ⁻⁶ <kr (9b)
8.0 × 10 ⁻⁶ <kr (9c)
1.0 × 10 ⁻⁵ <kr (9d)

As described above, an organic material having anomalous dispersion may be used as the material of the optical element OE1. Here, when the anomalous dispersion of the optical element OE1 with respect to the g-line and the F-line is ΔθgF, in order to satisfactorily correct the chromatic aberration in the optical system 100, it is desirable to satisfy the following conditional expression (10).
0.027 <| ΔθgF | (10)

Furthermore, it is more preferable to satisfy the following conditional expressions (10a) and (10b) in order.
0.050 <| ΔθgF | (10a)
0.10 <| ΔθgF | (10b)

Here, the refractive indices for the g-line (435.8 nm), F-line (486.1 nm), d-line (587.6 nm), and C-line (656.3 nm), which are Fraunhofer lines, are ng and nF, respectively. , Nd, nC. At this time, the Abbe number νd with respect to the d-line, the partial dispersion ratio θgF with respect to the g-line and the F-line, and the anomalous dispersion ΔθgF with respect to the g-line and the F-line are defined as the following equations (11) to (13). Is done.
νd = (nd−1) / (nF−nC) (11)
θgF = (ng−nF) / (nF−nC) (12)
ΔθgF = θgF − (− 1.665 × 10 ⁻⁷ νd ³ + 5.213 × 10 ⁻⁵ νd ² −5.656 × 10 ⁻³ νd + 0.7278) (13)

Note that when the material of the optical element OE1 is a solid material in which fine particles of an inorganic oxide (for example, TiO ₂ or ITO: Indium-Tin-Oxide) are used, light is scattered by the fine particles of the inorganic oxide. It is necessary to suppress this. For this purpose, it is preferable to set the particle diameter of the fine particles within a range of 2 nm to 50 nm. Further, a dispersant or the like may be added in order to suppress aggregation when the inorganic oxide fine particles are mixed with the solid material.

  Here, in a mixture in which fine particles are dispersed in a solid material (base material), the refractive index n (λ) with respect to the wavelength λ can be derived from a relational expression based on Maxwell-Garnett theory. Specifically, the refractive index n (λ) is expressed as follows when the relative permittivity of the solid material is εm, the relative permittivity of the fine particles is εp, and the fraction of the total volume of the fine particles with respect to the volume of the solid material is η. Based on the relative dielectric constant εav of the mixture defined by the equation (14), it is expressed as the following equation (15).

  As described above, according to the optical system 100 according to the present embodiment, excellent environmental resistance can be realized even when an optical element made of an organic material is used. If necessary, the optical system 100 may be provided with at least one of the optical element OE1, the light shielding unit MR1, and the ultraviolet reflection unit CU1 made of the organic material according to the present embodiment. In that case, it is desirable that at least one of the plurality of optical elements OE1, the plurality of light shielding units MR1, and the plurality of ultraviolet reflection units CU1 satisfy the above-described conditional expressions, and all satisfy the respective conditional expressions. Is more preferable.

  Next, examples of the optical system 100 according to the present embodiment will be described in detail.

[Example 1]
Hereinafter, the optical system 100 according to the first embodiment of the present invention will be described in detail. The optical system 100 according to the present example is the same as the optical system 100 according to the above-described embodiment.

  As shown in FIG. 1, the optical system 100 according to the present embodiment includes a first lens unit (lens group) L1 having a negative refractive power and a second lens unit L2 having a positive refractive power in order from the object side to the image side. And a third lens unit L3 having a positive refractive power. In the optical system 100, the interval between the lens units changes during focusing. Note that FIG. 1 shows a cross section when the optical system 100 is focused on an object at infinity, and an arrow in the figure indicates the direction in the optical axis direction of each lens unit during focusing from infinity to a short distance. The movement trajectory is shown. FIG. 2 is a schematic view (front view) of the light shielding means MR1 according to the present embodiment.

In the present embodiment, the optical element OE1 made of an organic material and the aperture stop SP are included in the third lens unit L3. Further, the light shielding means MR1 according to the present embodiment is configured by providing an opening MO in the light shielding portion MC that is a planar opaque member arranged perpendicular to the optical axis OA. It is arranged on the object side.
The maximum diameter of the opening MO of the light shielding means MR1 is 59.40 mm, the ratio of the area of the light shielding part MC to the area of the circle having the maximum diameter as the diameter is 0.189, the diameter MS and the length of the short side direction of the opening MO The diameter ML in the side direction is 43.8 mm and 53.7 mm, respectively.

Further, the optical element OE1 according to the present example is a refractive lens having a positive refractive power, which is made of a mixture in which TiO ₂ fine particles are dispersed in a volume ratio of 25% in a (meth) acrylic monomer, and the third lens unit L3. Is disposed on the image side of the aperture stop SP. The ratio of the refractive power of the optical element OE1 to the refractive power of the entire optical system 100 is 0.235. The material constituting the optical element OE1 has an anomalous dispersion characteristic and an absorption characteristic for the ultraviolet region, and the extinction coefficient kr at a wavelength of 360 nm is 1.14 × 10 ⁻⁵ .

Further, the optical system 100 according to the present embodiment includes an ultraviolet reflecting unit CU1 provided on the optical surface (exit surface) on the image side of the second optical element (second lens) from the object side. The optical surface provided with the ultraviolet reflecting means CU1 is a curved surface that is convex toward the object side. The ultraviolet reflecting means CU1 according to the present embodiment includes a base material made of S-NSL36 of OHARA INC. And SiO ₂ (nd = 1.46) and TiO ₂ (nd = 2.32) provided thereon. It is composed of a multilayer film including the same, and the passage of light in the ultraviolet region is suppressed using each interface. Table 1 shows the configuration of the ultraviolet reflecting means CU1 according to the present embodiment. In Table 1, nd represents the refractive index with respect to the d line (587.6 nm).

  FIG. 3 shows the transmittance characteristics of the ultraviolet reflecting means CU1 according to this embodiment. In FIG. 3, the solid line indicates the transmittance characteristic for the light beam perpendicularly incident on the ultraviolet reflecting means CU1, and the broken line indicates the transmittance characteristic for the light beam incident on the ultraviolet reflecting means CU1 at an incident angle of 50 °.

  From the solid line in FIG. 3, it can be seen that the transmittance with respect to a light beam having an incident angle of 0 ° changes rapidly in the vicinity of the ultraviolet region (near 400 nm), and a good ultraviolet light shielding effect is obtained. Specifically, the transmissivity of light incident perpendicularly to the ultraviolet reflecting means CU1 is 10%, 50%, and 90% for light with wavelengths of 376 nm, 390 nm, and 400 nm, respectively, and λ90-λ10 is 24 nm. Further, the transmittance with respect to light having a wavelength of 360 nm perpendicularly incident on the ultraviolet reflecting means CU1 is 3% or less, and the transmittance of light in the wavelength range of 480 nm to 660 nm is 95% or more.

  Further, as indicated by the broken line in FIG. 3, the transmittances with respect to a light beam having an incident angle of 50 ° are 10%, 50%, and 90%, respectively, for light having wavelengths of 353 nm, 367 nm, and 381 nm. From this, it can be seen that the ultraviolet light shielding effect is lower when a light beam having an incident angle of 50 ° is incident on the ultraviolet light reflecting means CU1.

  In the cross section including the maximum diameter of the opening MO of the light shielding unit MR1 and the optical axis OA, the maximum incident angle θc0 with respect to the ultraviolet reflecting unit CU1 of the light beam toward the intersection of the incident surface of the optical element OE1 and the optical axis OA is 39.9. °. Further, in the cross section including the minimum diameter of the opening MO of the light shielding means MR1 and the optical axis OA, the light beam that passes through the opening MO and travels toward the intersection of the incident surface of the optical element OE1 and the optical axis OA, with respect to the ultraviolet reflecting means CU1. The maximum incident angle θcS is 28.6 °. From this, it can be seen that the incident angle of the light incident on the ultraviolet reflecting means CU1 is sufficiently small.

  As described above, according to the optical system 100 according to the present embodiment, the light shielding unit MR1 and the ultraviolet reflection unit CU1 provided with the non-circular opening are arranged on the object side with respect to the optical element OE1, thereby entering the optical element OE1. UV rays can be shielded well.

[Example 2]
FIG. 4 is a cross-sectional view of an essential part of the optical system 200 according to the second embodiment of the present invention, and FIG. 5 is a schematic diagram of the light shielding means MR2 according to the present embodiment. In the optical system 200 according to the present embodiment, the description of the configuration equivalent to that of the optical system 100 according to the first embodiment is omitted.

  The optical system 200 according to the present embodiment includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power and a second lens unit L2 having a positive refractive power. In the optical system 200, as indicated by an arrow in the drawing, the second lens unit L2 moves in the optical axis direction during focusing from infinity to a short distance. In this embodiment, the optical element OE2 made of an organic material and the aperture stop SP are included in the first lens unit L1.

  The light shielding means MR2 according to the present embodiment is made of a thin film having absorption characteristics, and is provided on the optical surface closest to the object in the optical system 200. As a manufacturing method of the light shielding unit MR2, for example, a method of forming a film only in a region that does not contribute to image formation on the optical surface by vapor deposition using a mask can be employed. As shown in FIG. 5, the opening MO of the light shielding means MR2 is rectangular, its maximum diameter is 29.2 mm, and the value of the ratio of the area of the light shielding part MC to the area of the circle having the diameter as the maximum diameter is 0.420. The diameter MS in the short side direction and the diameter ML in the long side direction are 16.4 mm and 23.7 mm, respectively.

The optical element OE2 according to the present embodiment is a refractive lens having a positive refractive power made of (meth) acrylic monomer, and is disposed on the image side with respect to the aperture stop SP in the first lens unit L1. The ratio of the refractive power of the optical element OE2 to the refractive power of the entire optical system 200 is 0.208, and the extinction coefficient kr at a wavelength of 360 nm of the material constituting the optical element OE2 is 1.40 × 10 ^−5. It is. Thus, the material constituting the optical element OE2 has an anomalous dispersion characteristic and an absorption characteristic for the ultraviolet region.

  Furthermore, the optical system 200 according to the present embodiment includes the ultraviolet reflecting means CU2 provided on the concave emission surface of the fourth optical element (fourth lens) from the object side toward the object side. . In the cross section including the maximum diameter of the opening MO of the light shielding unit MR2 and the optical axis OA, the maximum incident angle with respect to the ultraviolet reflecting unit CU2 of the light beam directed to the intersection of the incident surface of the optical element OE2 and the optical axis OA is 41.7 °. It is. Further, in the cross section including the minimum diameter of the opening MO of the light shielding unit MR2 and the optical axis OA, the light beam that passes through the opening MO and travels to the intersection between the incident surface of the optical element OE2 and the optical axis OA, with respect to the ultraviolet reflecting unit CU2. The maximum incident angle θcS is 31.3 °.

[Example 3]
FIG. 6 is a cross-sectional view of a main part of an optical system 300 according to the third embodiment of the present invention, and FIG. 7 is a schematic diagram of the light shielding means MR3 according to the present embodiment. In the optical system 300 according to the present embodiment, the description of the configuration equivalent to that of the optical system 100 according to the first embodiment is omitted.

  The optical system 300 according to the present embodiment includes, in order from the object side to the image side, a first lens unit L1 having a positive refractive power, a second lens unit L2 having a positive refractive power, and a third lens unit L3 having a positive refractive power. It is composed of In the optical system 300, as indicated by the arrows in the figure, the second and third lens units L2 and L3 move in the optical axis direction during focusing from infinity to a short distance. In the present embodiment, the optical element OE3 made of an organic material is included in the second lens unit L2, and the aperture stop SP is included in the third lens unit L3.

  The light blocking means MR3 according to the present embodiment is made of an opaque member, and is provided between the first optical element (first lens) and the second optical element (second lens) from the object side in the optical system 300. Yes. As shown in FIG. 7, the opening MO of the light shielding means MR3 is rectangular, its maximum diameter is 40.9 mm, and the value of the ratio of the area of the light shielding part MC to the area of the circle having the diameter as the maximum diameter is 0.076. The diameter MS in the short side direction and the diameter ML in the long side direction are 35.1 mm and 38.9 mm, respectively.

The optical element OE3 according to the present embodiment is a refractive lens having a positive refractive power made of a (meth) acrylic monomer, and is disposed in the second lens unit L2 on the object side with respect to the aperture stop SP. The ratio of the refractive power of the optical element OE3 to the refractive power of the entire system of the optical system 300 is 0.124, and the extinction coefficient kr at the wavelength of 360 nm of the material constituting the optical element OE3 is 1.40 × 10 ^−5. It is. Thus, the material constituting the optical element OE2 has an anomalous dispersion characteristic and an absorption characteristic for the ultraviolet region.

  Furthermore, the optical system 300 according to the present embodiment includes an ultraviolet reflecting unit CU3 provided on a convex incident surface of the fifth optical element (fifth lens) from the object side in the optical system 300 toward the object side. Have. In the cross section including the maximum diameter of the opening MO of the light shielding unit MR3 and the optical axis OA, the maximum incident angle of the light ray toward the intersection of the incident surface of the optical element OE3 and the optical axis OA with respect to the ultraviolet reflecting unit CU3 is 7.0 °. It is. Further, in the cross section including the minimum diameter of the opening MO of the light shielding means MR3 and the optical axis OA, the light beam that passes through the opening MO and travels to the intersection of the incident surface of the optical element OE3 and the optical axis OA, with respect to the ultraviolet reflection means CU3. The maximum incident angle θcS is 7.4 °.

  Next, specific numerical data will be shown for numerical examples 1 to 3 corresponding to the first to third embodiments described above. However, in each numerical example, the surface number indicates the number of the optical surface counted from the light incident side, r indicates the radius of curvature of the optical surface, and d indicates the optical surface of the surface number and the optical surface of the next surface number. The distance on the axis (distance on the optical axis) is shown. Each of nd and νd indicates the refractive index and Abbe number of the medium between the optical surface with the surface number and the optical surface with the next surface number with respect to the d-line.

In each numerical example, BF indicates the back focus of the optical system, the unit of length (distance) is [mm], and the unit of field angle is [deg]. In each numerical example, an aspherical optical surface is given an asterisk (*) after the surface number. In addition, “e ± XX” in each aspheric coefficient means “× 10 ^{± XX} ”. The aspherical shape of the optical surface is such that the amount of displacement from the surface vertex in the optical axis direction is X, the height from the optical axis in the direction perpendicular to the optical axis direction is h, the paraxial radius of curvature is r, the conic constant is k, When the aspheric coefficients are B, C, D, E..., They are expressed by the following equation (16).

(Numerical example 1)
Surface number rd nd vd Effective diameter
1 ∞ 2.00 59.40
2 480.322 2.82 1.67270 32.1 55.79
3 36.983 6.74 47.80
4 119.552 2.46 1.51742 52.4 47.72
5 42.361 5.06 45.90
6 90.295 4.27 1.90366 31.3 46.24
7 -18601.026 0.15 46.10
8 93.603 3.43 1.58313 59.4 45.43
9 * 39.044 4.01 43.41
10 62.996 5.50 1.91082 35.3 43.38
11 -756.556 (variable) 42.91
12 37.467 5.79 1.83481 42.7 34.86
13 779.999 3.27 34.14
14 72.301 2.99 1.59522 67.7 30.47
15 -1236.876 1.50 1.72825 28.5 29.64
16 28.912 (variable) 26.78
17 (Aperture) ∞ 7.36 25.30
18 -18.879 1.64 1.84666 23.8 24.50
19 197.444 1.21 1.69934 26.4 28.47
20 -209.968 3.90 1.91082 35.3 28.61
21 -42.029 0.27 29.63
22 92.376 7.48 1.59522 67.7 31.68
23 -33.657 0.15 32.00
24 * -106.635 3.88 1.85400 40.4 33.05
25 -41.586 39.05 34.12
Image plane ∞

Aspheric data 9th surface K 0.00000e + 000 B = -3.29635e-006 C = -1.06088e-009 D = -8.09890e-012
E = 1.33588e-014 F = -9.49240e-018

24th surface K = 0.00000e + 000 B = -6.98994e-006 C = -7.36799e-010 D = -7.33127e-012
E = 6.43354e-015

Various data focal length 34.30
F number 1.45
Angle of View 32.24
Statue height 21.64
Total lens length 127.48
BF 39.05

Object distance infinity 1750 1000 500 300
d11 5.93 5.48 5.09 3.97 1.70
d16 8.60 8.30 8.07 7.45 6.48

Entrance pupil position 34.66
Exit pupil position -43.12
Front principal point position 54.64
Rear principal point position 4.75

Lens unit data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 -396.15 34.44 -96.68 -163.46
2 12 116.60 13.56 -20.89 -25.39
3 17 42.30 25.90 23.59 10.19

Single lens Data lens Start surface Focal length
1 2 -59.72
2 4 -128.19
3 6 99.45
4 8 -117.60
5 10 64.05
6 12 46.98
7 14 114.86
8 15 -38.77
9 18 -20.28
10 19 145.68
11 20 57.06
12 22 42.38
13 24 77.69

(Numerical example 2)
Surface number rd nd vd Effective diameter
1 49.172 0.00 29.18
2 49.172 1.80 1.72916 54.7 29.18
3 7.731 8.54 15.12
4 11.844 1.83 1.74320 49.3 11.33
5 8.327 2.25 9.43
6 39.257 2.03 1.84666 23.8 8.62
7 -45.502 1.21 7.78
8 -13.730 3.85 1.72916 54.7 7.07
9 -10.941 0.69 8.22
10 (Aperture) ∞ 2.62 8.21
11 21.663 2.39 1.49700 81.5 8.18
12 -13.589 0.52 7.99
13 -15.907 0.64 1.72825 28.5 8.27
14 9.609 0.57 1.63556 22.7 9.69
15 13.950 3.25 1.65 160 58.5 9.79
16 -27.106 (variable) 11.02
17 * -52.965 2.04 1.58313 59.4 15.91
18 -19.867 (variable) 16.68
Image plane ∞

Aspheric data 17th surface K = 0.00000e + 000 B = -6.57616e-005 C = 2.99433e-007 D = -4.07412e-009
E = 2.53079e-011 F = -2.25245e-014

Various data focal length 9.60
F number 2.80
Angle of View 181.7
Statue height 13.66
Total lens length 55.13
BF (variable)

Object distance infinity 480 90
d16 5.89 5.44 1.79
d18 (BF) 15.00 15.46 19.11

Entrance pupil position 8.62
Exit pupil position -22.89
Front principal point 15.79
Rear principal point position 5.40

Lens unit data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 13.10 32.19 16.93 14.25
2 17 53.31 2.04 2.02 0.76
Single lens Data lens Start surface Focal length
1 2 -12.82
2 4 -48.47
3 6 25.17
4 8 46.68
5 11 17.19
6 13 -8.14
7 14 46.21
8 15 14.59
9 17 53.31

(Numerical Example 3)
Surface number rd nd vd Effective diameter
1 72.080 2.65 1.58313 59.4 50.00
2 * 25.512 11.00 41.33
3 ∞ 2.45 40.87
4 -96.609 2.50 1.48749 70.2 40.75
5 66.944 3.13 39.59
6 175.419 5.63 1.91082 35.3 39.68
7 -77.862 3.86 39.54
8 -44.606 2.30 1.69895 30.1 38.10
9 -178.782 0.15 38.34
10 62.257 8.11 1.59522 67.7 38.01
11 -59.637 (variable) 37.40
12 48.797 4.61 2.00 100 29.1 35.03
13 9939.838 1.32 34.39
14 333.607 4.76 1.60311 60.6 32.67
15 -61.478 1.00 1.63556 22.4 31.18
16 -45.844 1.59 1.72825 28.5 30.99
17 32.360 (variable) 27.20
18 (Aperture) ∞ 7.17 26.60
19 -21.286 1.40 1.69895 30.1 25.93
20 177.619 4.21 1.59522 67.7 28.93
21 -52.749 0.15 29.70
22 97.355 7.19 1.59522 67.7 31.37
23 -35.549 0.15 32.12
24 * -158.409 4.26 1.85400 40.4 33.44
25 -43.693 (variable) 34.50
Image plane ∞

Aspheric data 2nd surface
K = 0.00000e + 000 B = -1.26283e-006 C = -4.27073e-009 D = 5.04254e-012 E = -1.12945e-014
24th page
K = 0.00000e + 000 B = -6.35905e-006 C = -4.47403e-010 D = -4.21764e-012 E = 2.36025e-015

Various data focal length 34.30
F number 1.45
Angle of View 32.24
Statue height 21.64
Total lens length 131.15
BF 39.00

Object distance infinity 1750 300
d11 7.06 6.32 0.80
d17 5.50 5.50 5.50
d25 39.00 39.74 45.26

Entrance pupil position 35.71
Exit pupil position -37.10
Front principal point position 54.55
Rear principal point position 4.70

Lens unit data group Start surface Focal length Lens configuration length Front principal point position Rear principal point position
1 1 170.03 41.79 78.71 82.50
2 12 783.13 13.28 -152.17 -134.21
3 18 44.42 24.52 22.40 8.09

Single lens Data lens Start surface Focal length
1 1 -69.17
2 4 -80.71
3 6 59.84
4 8 -85.64
5 10 52.48
6 12 48.98
7 14 86.47
8 15 276.77
9 16 -25.83
10 19 -27.12
11 20 68.80
12 22 44.65
13 24 69.46

  Table 2 shows numerical values of the algebra part in the conditional expressions (1) to (10) for the optical systems according to the numerical examples, and Table 3 shows an optical element composed of an organic material according to the numerical examples. The optical characteristics of are shown. Table 4 shows the base material of the mixture constituting the optical element made of the organic material according to Example 1, and the optical characteristics of the mixed fine particles.

[Optical equipment]
FIG. 8 is a main part schematic diagram of an imaging apparatus (digital still camera) as an optical apparatus according to an embodiment of the present invention. The image pickup apparatus according to the present embodiment receives light from the camera body 10, the optical system (shooting optical system) 11 according to any of the above-described embodiments, and the shooting optical system 11. And a light receiving element (imaging element) 12 that photoelectrically converts a formed subject image. The imaging optical system 11 is held by a lens barrel (holding member) and connected to the camera body 10.

  According to the imaging apparatus according to the present embodiment, by employing the optical system according to any of the above-described examples, high optical performance can be obtained, and a high-quality image can be acquired. . As the light receiving element 12, a solid-state imaging device (electronic imaging device) such as a CCD sensor or a CMOS sensor can be used. At this time, it is possible to improve the image quality of the output image by electrically correcting various aberrations such as distortion and chromatic aberration of the image acquired by the light receiving element 12.

  In FIG. 8, the camera body 10 and the photographing optical system 11 are integrated as an optical apparatus according to this embodiment, but the camera body 10 and the photographing optical system 11 are configured to be detachable from each other. May be. That is, an interchangeable lens including the photographing optical system 11 and the lens barrel (holding member) may be configured as the optical apparatus according to the present embodiment. The optical system according to each of the above-described embodiments is not limited to the digital still camera shown in FIG. 8, but is applied to various optical devices such as a silver salt film camera, a video camera, a telescope, binoculars, a projector, and a digital copying machine. Can be applied.

  The preferred embodiments and examples of the present invention have been described above, but the present invention is not limited to these embodiments and examples, and various combinations, modifications, and changes can be made within the scope of the gist.

OA Optical axis SP Aperture stop IP Image surface (light receiving surface)
MR1 light shielding means OE1 optical element composed of organic material

Claims (18)

An optical system for imaging an object on a light receiving surface,
An optical element composed of an organic material, a light shielding means disposed closer to the object side than the optical element, and an aperture stop,
The light shielding means is provided with a non-circular opening,
The distance between the position of the light beam passing through the center of the aperture stop and the optical axis of the light beam traveling toward the most off-axis image height on the light receiving surface is hp, and the on-axis image height on the light receiving surface. When the maximum distance between the optical axis and the position where the light beam traveling to the light-shielding means passes through the opening is ha, and the distance on the optical axis between the light-shielding means and the incident surface of the optical element is Lr,
0.020 <tan ⁻¹ (ha / Lr) / tan ⁻¹ (hp / Lr) <0.95
An optical system that satisfies the following conditional expression: 0.10 <hp / Lr <1.0
The optical system according to claim 1, wherein the following conditional expression is satisfied. The distance between the optical axis of the light beam that passes through the center of the aperture stop and the optical axis among the light fluxes toward the most off-axis image height on the light receiving surface is hp0, and the light shielding means and the most object When the distance on the optical axis with the optical surface on the side is Lm,
0 ≦ Lm / hp0 <1.0
The optical system according to claim 1, wherein the following conditional expression is satisfied.   The optical system according to any one of claims 1 to 3, further comprising an ultraviolet reflecting unit that reflects ultraviolet rays and is disposed closer to the object side than the optical element.   5. The optical system according to claim 4, wherein the transmittance of the ultraviolet reflecting means is 20% or less with respect to light having a wavelength of 360 nm perpendicularly incident on the ultraviolet reflecting means. In a cross section including the minimum diameter of the opening of the light shielding means and the optical axis, the maximum incident angle with respect to the ultraviolet reflection means of the light beam that passes through the opening and goes to the intersection of the incident surface of the optical element and the optical axis is θcS. And when
θcS <45 °
The optical system according to claim 4, wherein the following conditional expression is satisfied. The optical system according to claim 4, wherein the ultraviolet reflecting means includes TiO ₂ . When the wavelength of the light is λ50 when the transmittance of the ultraviolet reflecting means is 50% with respect to the light perpendicularly incident on the ultraviolet reflecting means,
365 nm ≦ λ50 ≦ 430 nm
The optical system according to claim 4, wherein the following conditional expression is satisfied. When the wavelengths of the light when the transmittance of the ultraviolet reflecting means is 10% and 90% with respect to light perpendicularly incident on the ultraviolet reflecting means are λ10 and λ90, respectively,
λ90-λ10 ≦ 30nm
The optical system according to claim 4, wherein the following conditional expression is satisfied.   The optical system according to claim 1, wherein the shape of the opening of the light shielding unit is a rectangle. In the light shielding means, when the circle having the maximum diameter of the opening and the area of the light shielding portion are S0 and Sc, respectively,
0.020 <Sc / S0 <0.50
The optical system according to claim 1, wherein the following conditional expression is satisfied.   12. The optical system according to claim 1, further comprising an optical element made of an inorganic material, disposed between the light shielding unit and the optical element.   The optical system according to claim 1, wherein the optical element is made of a resin that is cured by irradiation with ultraviolet rays. When the refractive power of the optical element and the whole system is φr and φ, respectively,
0.010 <φr / φ
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the extinction coefficient for light having a wavelength of 360 nm of the organic material constituting the optical element is kr,
5.0 × 10 ⁻⁶ <kr
The optical system according to claim 1, wherein the following conditional expression is satisfied. When the anomalous dispersion for the g-line and F-line of the optical element is ΔθgF,
0.027 <| ΔθgF |
The optical system according to claim 1, wherein the following conditional expression is satisfied.   An optical apparatus comprising: the optical system according to any one of claims 1 to 16; and a light receiving element including the light receiving surface.   18. The optical device according to claim 17, wherein each of the opening of the light shielding unit and the light receiving surface has a rectangular shape, and a short side direction of the opening and a short side direction of the light receiving surface are aligned with each other. machine.

Images