WO2015155842A1

WO2015155842A1 - Optical component and imaging device using same

Info

Publication number: WO2015155842A1
Application number: PCT/JP2014/060218
Authority: WO
Inventors: 太田　光彦; 島野　健; 崎田　康一
Original assignee: 日立マクセル株式会社
Priority date: 2014-04-08
Filing date: 2014-04-08
Publication date: 2015-10-15

Abstract

The purpose of the present invention is to provide an optical component (phase modulation element) and an imaging device using the optical component, the optical component capable of reducing the dimensional accuracy required for setting a phase modulation surface and suppressing PSF peaks. In order to add a prescribed blur to an optical image in an imaging device having a function of enlarging the depth of focus, the present invention provides an optical component that is incorporated in the optical system of the imaging device and is characterized by having a plurality of ring segments, with a height difference in the optical axis direction being provided between at least a pair of the ring segments.

Description

Optical component and imaging apparatus using the same

The present invention relates to an optical component used for enlarging the depth of field or enlarging the depth of focus, and an imaging apparatus using the same.

As a background art in this technical field, for example, the one described in US Pat. No. 5,748,371 (Patent Document 1) is known. A phase modulation element that modulates the phase of light is arranged in the optical system, and a point spread function (PSF: Point Spread Function, hereinafter referred to as “PSF”) is essentially within a certain distance from the focal point position. And a technique for expanding the depth of field or the depth of focus is disclosed.

JP 2013-518474 A (Patent Document 2) describes an example in which an axially symmetric phase modulation element having a random one-dimensional profile in the radial direction is used in the above phase modulation element. .

Also, in these prior arts (hereinafter referred to as “prior art”), a technique is disclosed in which a modulated intermediate image caused by a PSF modulated by a phase modulation element is removed by signal processing to expand the depth of field. .

US Pat. No. 5,748,371 Special table 2013-518474 gazette

In the above prior art, in Patent Document 1, since the phase modulation element that modulates the phase is non-rotationally symmetric with respect to the optical axis, the PSF depends on the amount of deviation (defocus amount) from the in-focus position. There was a problem that the center of gravity moved.
In addition, there is a problem that a ghost image having a directivity is generated when a modulation component caused by the phase modulation element is removed from the modulated intermediate image by signal processing.
In addition, the PSF also rotates with the rotational shift of the phase modulation element, and there is a problem that the reproduced image deteriorates.
Further, the phase modulation element has a problem that a light amount loss occurs because it is necessary to provide a rectangular diaphragm.

In order to solve the above problem, Patent Document 2 describes an example using a phase modulation element that is symmetric with respect to the rotation axis, and has a phase modulation surface that is set using randomness, Uniform PSF independent of defocusing is realized by averaging the randomness.

However, in Patent Document 2 described above, since the shape of the phase modulation element is determined by a stochastic model using statistical optics, it is necessary to set a relatively large number of ring zones constituting the phase modulation surface, and high dimensional accuracy is required. . In Patent Document 2, depending on the setting of the annular zone, a PSF peak (hereinafter referred to as “PSF peak”) may occur at a specific position in the optical axis direction due to interference between the annular zones. Since the generation of this PSF peak is not mentioned in the above-mentioned Patent Document 2, there is room for further research.

Accordingly, the present invention provides an optical component (phase modulation element) capable of reducing the dimensional accuracy required for setting the phase modulation surface and suppressing the occurrence of PSF peaks, and an imaging apparatus using the same. .

In order to achieve the above object, the present invention is an optical component that includes a plurality of annular zones defined by a plurality of concentric circles, and is configured to be rotationally symmetric with respect to the center of the concentric circles. A cross-sectional shape in a direction perpendicular to the concentric circle and passing through the center of the concentric circle has a concave or convex surface, and the position of the surface of one of the annular zones and the other The position of the surface of the annular zone is different in a direction perpendicular to the concentric circles.

Further, the present invention is an imaging apparatus including a plurality of annular zones defined by a plurality of concentric circles and including an optical component configured to be rotationally symmetric with respect to a center of the concentric circles, wherein the annular zones are the concentric circles. A cross-sectional shape in a direction perpendicular to the center and passing through the center of the concentric circle has a concave or convex surface, and the position of the surface of one of the annular zones and the other ring The position of the surface of the belt includes the optical component that is different in a direction perpendicular to the concentric circle.

According to the optical component (phase modulation element) of the present invention, the optical component (phase modulation element) capable of reducing the dimensional accuracy required for setting the phase modulation surface and suppressing the occurrence of the PSF peak, and the same An imaging apparatus using the can be provided.

It is a figure which shows the structural example of the imaging device using the phase modulation element of this invention. It is a figure which shows the structure of the phase modulation element in Example 1 of this invention. FIG. 6 is a diagram illustrating a configuration of a modified example (modified examples 1 to 4) of the first embodiment. It is a figure which shows the structure of the phase modulation element of an Example (Example 1 ') in the progress stage which reaches the structure of the phase modulation element which concerns on the present Example 1. FIG. It is a figure which shows the structure of the modification (modification 5) of Example 1. FIG. It is a figure which shows PSF by a normal imaging optical system. It is a figure which shows PSF by the imaging optical system using the phase modulation element which concerns on Example 1 '(FIG. 4). It is a figure which shows PSF by the imaging optical system using the phase modulation element which concerns on Example 1 (FIG. 2). It is a figure which shows the conditions of the level | step difference between ring zones in Example 1. FIG. It is a figure which shows PSF by the imaging optical system using the phase modulation element which concerns on the modification 4 (FIG.3 (d)). It is a figure which shows PSF by the imaging optical system using the phase modulation element which concerns on the modification 5 (FIG. 5). It is the image acquired by the imaging device using the present invention. It is the image acquired by the normal imaging device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Example 1
FIG. 1 is a diagram illustrating a configuration example of the imaging apparatus according to the present embodiment.
The imaging apparatus 100 according to the first embodiment can be applied to, for example, an AV camera, a mobile phone mounted camera, a portable information terminal mounted camera, an image inspection apparatus, an industrial camera for automatic control, and the like.

The imaging apparatus 100 includes an optical system 2, an imaging device 3, an A / D converter 4, a RAW buffer memory 5, an image correction unit 6, and an output unit 7. The optical system 2 includes a front lens group 23, a rear lens group 24, a diaphragm 22, and a phase modulation element 21.

The diaphragm 22 is provided between the front lens group 23 and the rear lens group 24 and plays a role of appropriately narrowing the light beam emitted from the subject 1 and transmitted through the optical system 2. The phase modulation element 21 is provided in the vicinity of the diaphragm 22. The phase modulation element 21 has a configuration as shown in FIG. 2 and later described later, and has a function of modulating the phase of a light beam transmitted through the optical system 2.

The light beam emitted from the subject 1 and incident on the optical system 2 forms a subject image on the surface of the image sensor 3 by the functions of the front lens group 23 and the rear lens group 24. Due to the effect of the phase modulation of the light beam by the phase modulation element 21, the amount of blur of the subject image is substantially constant over a wide range.

The image sensor 3 has a plurality of pixels on its surface. The subject image formed on the surface of the image sensor 3 is converted into an analog signal for each pixel by the image sensor 3, and further converted into a digital signal by the A / D converter 4, and image data corresponding to the subject image is obtained. Generated.

The RAW buffer memory 5 stores the image data from the A / D converter 4. The image correction unit 6 receives the image data from the RAW buffer memory 5 and performs a correction process for removing the blur of the subject image caused by the phase modulation of the phase modulation element 21. The correction processing method may be, for example, a method using a spatial filter. The corrected image is supplied to the output unit 7.

An image acquired by such an imaging apparatus (imaging apparatus 100 according to the first embodiment) is shown in FIG. It can be seen that the fingerprint of a finger a few cm away from the camera and the letters on the sticker a distance of 5 cm or more from the camera are resolved.
It can also be seen that subjects such as test charts at an intermediate distance are also resolved.

FIG. 13 shows an image acquired by a normal imaging device (imaging device according to the prior art) for comparison with FIG. The two-dimensional barcode at a distance of about 10 cm from the camera is in focus, but the image of the finger in front of it and the test chart and sticker behind it are blurred.

The first embodiment uses the phase modulation element 21 having a plurality of concentric annular zones as the phase modulation element 21 included in the optical system 2 in the imaging apparatus or imaging system having the above-described configuration. The details will be described below with reference to FIGS. In the first embodiment, the phase modulation element 21 has an axisymmetric shape and is composed of a plurality of annular zones.

FIG. 2 shows a typical configuration example of the first embodiment. 2A is a view of the phase modulation element 21 as viewed from the optical axis direction, and FIG. 2B is a cross-sectional view taken along the central axis. The optical axis direction is a direction perpendicular to a plurality of concentric circles that define a plurality of annular zones.

3A to 3D show other configuration examples of the first embodiment. In the following, FIG. 3A is a first modification of the first embodiment (simply referred to as “first modification”), and FIG. 3B is a second modification of the first embodiment (“modified example”). 2 ”), FIG. 3C is a third modification of the first embodiment (referred to as“ third modification ”), and FIG. 3D is a fourth modification of the first embodiment (“ modified example ”). 4 ”).

2 and 3, the phase modulation element 21 has a four-zone configuration, but the number of zones in the first embodiment and each modification is not limited to the four-zone. Moreover, although each ring zone is expressed by the same width, it does not necessarily need to be the same width.

In the first embodiment and each modified example, the surface of each annular zone has a convex shape or a concave shape, and FIG. 2 (b), FIG. 3 (c), and FIG. FIG. 3A and FIG. 3B show configuration examples in which the surface of each annular zone has a concave shape. In FIG. 2B, FIG. 3C, and FIG. 3D, symbols h ₁ , h ₂ , h ₃ , and h ₄ indicating the respective heights are shown on the convex portions of the annular zones. In 3 (a) and FIG. 3 (b), symbols of h ₁ , h ₂ , h ₃ , and h ₄ indicating the respective depths are attached to the concave portions of the annular zones.
In FIGS. 2 and 3, the convex and concave portions of each zone are expressed in the same shape, but are not necessarily in the same shape.

Further, in the first embodiment, the step d is provided in the optical axis direction between the annular zones, so that the positions of the surfaces of all adjacent sets of annular zones are different in the optical axis direction. In the first embodiment, the portion indicated by the height or depth h ₁ , h ₂ , h ₃ , h ₄ is referred to as the surface of the annular zone, and the boundary with the portion indicated by the step d (that is, h ₁ , h ₂ , h ₃ , and h ₄ are positions at 0) is called the position of the surface of the annular zone. Thus, “the position of the surface of the annular zone is different” means that the position of the boundary between the surface of the annular zone and the portion indicated by the step d is different. That is, the fact that the position of this boundary is different means that a step d is provided.

Here, the m-th zone (m = 1, 2,..., The number of zones) counted from the center is expressed as the m-th zone, and the coordinate axis r is taken in the radial direction of the phase modulation element 21, outermost coordinates normalized to be 1, it represents the r-coordinate of the center r ₀ and ₍₌ 0), the coordinates of the outer circumferential end point of the m zones to be represented as r _m. In addition, the coordinate axis z is taken in the optical axis direction of the phase modulation element 21, and the step _dij between the i-th zone and the j-th zone is defined by Expression (1). However, the code | symbol of the coordinate axis z is as having described in FIG.2 (b), and is i <j.

With this definition, the steps d ₁₂ , d ₂₃ , and d ₃₄ shown in FIG. 2B are all positive values.

As shown in FIGS. 2B and 3A, the level difference d _ij may be a positive value in all (i, j) pairs, or as shown in FIG. 3B. , All (i, j) pairs may be negative values. Further, in FIG. 3 _{(c), d 23} is a negative _value, but d _{12, d 34} is a positive value, thus, a positive or negative value in step _{d ij} may be mixed. However, from the viewpoint of the difficulty of manufacturing and the difficulty of securing the angle of view performance, it is desirable that the peak to peak value of the phase modulation surface is small. From this viewpoint, the step _dij is a positive value or a negative value. It is preferable to unify

Further, the steps d _ij are not necessarily provided between all the annular zones, and may be configured such that d ₁₂ = 0 as shown in FIG. 3D, for example.

Next, the effect of the level difference d in the first embodiment will be described with reference to FIGS. 4 and 6 to 8.
FIG. 4 is a diagram illustrating the configuration of the phase modulation element 21 of the embodiment (for convenience, referred to as “Example 1 ′”) at the stage of reaching the configuration of the phase modulation element 21 according to the first embodiment.
6 to 8 show the results of calculating the PSF in the imaging optical system. Here, calculation conditions for PSF calculation will be described. The image side NA (Numerical Aperture) was set to 0.3926. Assuming that the light source is a visible light source with a uniformly distributed wavelength, PSFs were calculated once for each wavelength in 3 nm increments in the range of 405 nm to 705 nm, and the average of these was used as the PSF calculation result.

FIG. 6 is a PSF in a normal imaging optical system (imaging optical system according to the prior art). In both FIGS. 6A and 6B, the horizontal axis indicates the optical axis direction, and FIG. The vertical axis of a) represents the radial direction of the imaging surface, and the luminance represents the intensity of PSF. FIG. 6B is a cross section at the radial position = 0 in FIG. 6A, and the vertical axis represents the intensity of PSF. As can be seen from this figure, when the PSF in a normal imaging optical system is shifted in the direction of the optical axis, the intensity rapidly decreases.

FIG. 7 shows an imaging optical system equipped with a phase modulation element 21 (phase modulation element 21 according to Example 1 ′) that is composed of a plurality of annular zones but does not have a step d as shown in FIG. PSF in the system. 7A and 7B are the same as those in FIGS. 6A and 6B, and the description thereof is omitted. 7A and 7B, although the PSF is enlarged in the optical axis direction, a peak is formed at the optical axis direction position = 0. Therefore, the shape of the PSF is in the optical axis direction. It turns out that it is no longer constant.

Here, the cause of the peak will be described with reference to FIG. Hereinafter, for the sake of explanation, the PSF generated by the m-th annular zone of the phase modulation element 21 will be referred to as PSF _m , and the PSF generated from all the annular zones will be referred to as a PSF sum. The horizontal axis of FIG.7 (c) has shown the optical axis direction, the vertical axis | shaft represents a wavelength and the brightness | luminance represents the intensity | strength of PSF. FIG. 7C shows a stripe pattern due to a change in luminance, which means that the intensity of the PSF sum is generated by interference between the PSF _m . At optical axis direction positions other than optical axis position = 0, even if the intensity of the PSF sum is strong or weak, the strengths cancel each other out by averaging in the wavelength direction, and the intensity of the PSF sum after averaging is equal to the optical axis direction. It becomes a substantially constant value in a wide range. However, as can be seen from FIG. 7C, when the optical axis direction position = 0, the intensity of the PSF sum is strong regardless of the wavelength and does not cancel each other even if averaged. This is the cause of the peak at the optical axis direction position = 0.

FIG. 8 is a PSF in the imaging optical system on which the phase modulation element 21 of Example 1 provided with the step d as shown in FIG. 2 is mounted. 8 (a) and 8 (b) are the same as FIG. 6 (a) and FIG. 6 (b), and FIG. 8 (c) is the same as FIG. .

In FIG. 8, the PSF is enlarged in the optical axis direction, and no peak is generated. For this reason, the shape of PSF is substantially constant over a wide range in the optical axis direction. For this reason, in the imaging optical system in which the phase modulation element 21 of Example 1 is mounted, it is possible to obtain a focal depth expansion effect. Thus, the step d has an effect of removing the PSF peak. Comparing FIG. 8C with FIG. 7C, it can be seen that the position in the optical axis direction where the intensity of the PSF sum is strong is shifted to the minus side regardless of the wavelength. That is, the PSF peak is driven out of the range where the intensity of the PSF sum is substantially constant.

Next, the necessary amount of the step d will be described with reference to FIG. 3D, FIG. 5, and FIGS.
FIG. 5 is a diagram illustrating the configuration of the phase modulation element 21 according to the fifth modification example of the first embodiment (denoted as “fifth modification example”).

First, conditions for removing the PSF peak generated by the combination of the i-th zone and the j-th zone will be described. _Let z _{p be} the appearance position of the PSF peak in the optical axis direction. Further, assuming that the annular zone that generates PSF _m having the maximum contribution to the PSF sum is the M-th annular zone, the range in the optical axis direction in which the intensity of PSF _M is substantially constant (z _M > z > −z _M ). Then, the expression (2) is a condition for removing the PSF peak.

Next, a method for determining the _{z M.} An expression representing the complex amplitude Ψ _m (z, ρ) of PSF _m is shown in (3).

Here, z is the position in the optical axis direction, ρ is the radial position of the image plane, λ is the wavelength, NA is the image side NA in the imaging optical system, and f (·) is the light on the phase modulation surface of the m-th annular zone. A function representing the coordinates in the axial direction, n is the refractive index of the phase modulation element 21, J ₀ (·) is a zeroth-order first-type Bessel function, and C is an appropriate constant. Since C is irrelevant in the following description, description thereof is omitted.

Applying the stationary phase approximation method in Equation (3),

It becomes. The condition for this approximate solution is

The intensity of PSF _m represented by complex amplitudes Ψ _m and | Ψ _m | ² takes a substantially constant value in the range in the optical axis direction. Therefore, _{z M} is expressed by the equation (6).

The magnitude of the contribution to the PSF sum for each ring zone can be evaluated by | Ψ _m (z, 0) | in Expression (4). Since J ₀ (0) = 1, and λ and n do not depend on the annular zone, Equation (7) is obtained.

It is. Thus, M-th annular zone _can be identified by examining the ^{_{^{(r m 2 -r m-1}}} 2) / √h m.

Next, a method for obtaining z _p will be described. In order to obtain z _p , it is necessary to examine the state of the phase in the optical axis direction of each annular zone by modifying equation (3). Hereinafter, the equation is modified. In equation (3), ρ = 0 is set, and f (r) = 0 is approximated.

In this equation (8), when r ² = t is substituted,

When the integration of equation (9) is executed, equation (10) is obtained.

It becomes. In Expression (10), the term exp is the phase term of the m-th annular zone.

When the step d _ij is provided in the i-th zone and the j-th zone, the phase terms are expressed as follows.

The position z in the optical axis direction where the phases are aligned regardless of the wavelength in the i-th zone and the j-th zone is obtained as follows.

This z is the appearance position z _p of the PSF peak in the optical axis direction. That is,

The _dij satisfying the expression (2) is expressed as follows from the expressions (6) and (14).

Here, the phase modulation element 21 has a ring number of 4, r ₁ = 0.25, r ₂ = 0.5, r ₃ = 0.75, r ₄ = 1, h ₁ = h ₂ = h ₃ = h _4. When | d _ij | satisfying Expression (15) is calculated for all (i, j) pairs under the condition of = h, the result shown in FIG. 9A is obtained. A step satisfying this condition can be realized, for example, with a size as shown in FIG. The PSF previously shown in FIG. 7 is the result of calculation under this condition. However, the first embodiment does not necessarily require that Formula (15) is satisfied for all (i, j) pairs.

Here, the condition of the ring set that needs to satisfy the expression (15) will be described. In a set of (i, j), the condition for generating a PSF peak in the range of z _M >z> −z _M is set. Even if it is, if the peak intensity is sufficiently smaller than the intensity of the PSF sum, the change in the intensity of the PSF sum can be regarded as substantially constant in the range of z _M >z> −z _M. That is, if the degree of contribution to the PSF sum of the i-th zone and the j-th zone is small, the performance is not affected even if d _ij does not satisfy Expression (15). For example, the phase modulation element 21 has an annular number of 4, r ₁ = 0.25, r ₂ = 0.5, r ₃ = 0.75, r ₄ = 1, and h ₁ = h ₂ = h ₃ = h. _{When 4} , the value of (r _m ² −r _m−1 ² ) / √h _m is the minimum when m = 1, and the second smallest value when m = 2. At this time, even if d ₁₂ does not satisfy Expression (15) and d ₁₂ = 0, the performance is hardly affected. FIG. 3D is a configuration example showing the phase modulation element 21 under this condition.

FIG. 10 is a PSF in the imaging optical system on which the phase modulation element 21 having the configuration example of FIG. The calculation conditions and how to read the figure are the same as in FIG. In FIG. 10, the PSF is enlarged in the optical axis direction, and the influence of inter-annular interference by the first and second annular zones is small, so that a peak is almost generated at the optical axis direction position = 0. For this reason, the shape of the PSF is substantially constant over a wide range in the optical axis direction. For this reason, in the imaging optical system in which the phase modulation element 21 having the configuration example of FIG.
Further, in the configuration example of FIG. 3D, the value of peak to peak on the phase modulation surface can be made smaller than in the configuration example of FIG.

On the other hand, in the ring set having a large contribution to the PSF sum, the intensity of the generated PSF peak is relatively large unless _dij satisfies the equation (4), and the PSF sum is not substantially constant. Therefore, it is necessary to satisfy Equation (15) at least for the set of the annular zone having the largest contribution to the PSF sum and the second largest annular zone.

FIG. 5 is a configuration example of the phase modulation element 21 that does not satisfy the formula (15) in the set of the annular zone having the largest contribution to the PSF sum and the second largest annular zone. The phase modulation element 21 shown in FIG. 5 has an annular number 4, r ₁ = 0.25, r ₂ = 0.5, r ₃ = 0.75, r ₄ = 1, and h ₁ = h ₂ = Since h ₃ = h ₄ , the value of (r _m ² −r _m−1 ² ) / √h _m is the maximum when m = 4, and the second largest value when m = 3. And d ₃₄ = 0.

FIG. 11 is a PSF in the imaging optical system on which the phase modulation element 21 having the configuration example of FIG. 5 is mounted. The calculation conditions and how to read the figure are the same as in FIG. In FIG. 11, the PSF is enlarged in the optical axis direction, but a peak is clearly generated at the optical axis direction position = 0.

As described above, according to the first embodiment and the first to fourth modifications, the following effects can be obtained.

That is, by forming the phase modulation element 21 from a plurality of annular zones and satisfying the above formula (15) for the step d between the annular zones, the occurrence of PSF peaks can be suppressed. Note that the upper limit (maximum value) of the step d may be appropriately determined for each product in which the phase modulation element 21 is incorporated. However, it is desirable to reduce the thickness of the phase modulation element 21 from the viewpoint of maintaining the optical performance of the phase modulation element 21 such as the relationship between the number of annular zones of the phase modulation element 21 and the minimum value of the step d. .

Furthermore, according to the first embodiment and the first to fourth modifications, the following effects are further obtained.
That is, the center of gravity of the PSF does not change depending on the defocus amount in principle. In addition, since PSF is also rotationally symmetric and isotropically expanded, the restored image by signal processing does not have directionality, image degradation due to rotational deviation of the optical axis of the phase modulation element can be suppressed, and the rectangular aperture can be reduced. There is no light loss due to the provision.
Further, since PSF is also rotationally symmetric, it is possible to reduce the memory for storing the coefficient matrix used for signal processing, and to reduce the size of the signal processing circuit.
Furthermore, since it has a rotationally symmetric shape, the mold used for the molding also has a rotationally symmetric shape, enabling rotary lathe processing, shortening the processing time, and reducing manufacturing costs.
In addition, since the number of ring zones on the phase modulation surface can be set relatively small, the required dimensional accuracy is reduced.

In addition, the above-described effect can also be achieved by the above-described modification 5. That is, it is not necessary to provide a step between all the adjacent annular zones, and the position of the surface of one annular zone and the position of the surface of the other annular zone among the plurality of annular zones constituting the phase modulation element 21 are: By configuring differently in the optical axis direction, the above-described effects can be achieved. Although inferior to the first embodiment and the first to fourth modifications, the PSF peak can be suppressed as compared with a normal imaging optical system (prior art).
Note that the above-described effects can also be achieved by the embodiment (“embodiment 1 ′”) in the progress stage leading to the configuration of the phase modulation element 21 according to the first embodiment. It is also added that it is possible to suppress the PSF peak as compared with a normal imaging optical system (conventional technology).

In addition, this invention is not limited to an above-described Example and each modification, Various modifications are included. For example, the above-described embodiments and modifications have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described.
In addition, a part of the configuration of a certain embodiment or modification can be replaced with the configuration of another embodiment or modification, and the configuration of a certain embodiment or modification can be replaced with that of another embodiment or modification. It is also possible to add a configuration. In addition, it is possible to add, delete, and replace other configurations for a part of the configurations of the embodiments and the modifications.

DESCRIPTION OF SYMBOLS 1 Subject 2 Optical system 3 Image pick-up element 4 A / D converter 5 RAW buffer memory 6 Image correction part 7 Output part 21 Phase modulation element 22 Aperture 23 Front lens group 24 Rear lens group 100 Imaging device

Claims

An optical component including a plurality of annular zones defined by a plurality of concentric circles and configured to be rotationally symmetric with respect to a center of the concentric circles;
The annular zone has a concave or convex surface in a cross-sectional shape in a direction perpendicular to the concentric circle and passing through the center of the concentric circle,
An optical component, wherein a position of the surface of one annular zone and a position of the surface of another annular zone are different in a direction perpendicular to the concentric circles.
The optical component of claim 1,
An optical component characterized in that a cross-sectional shape of the annular zone is a convex shape.
The optical component of claim 1,
An optical component, wherein the annular zone has a concave cross-sectional shape.
The optical component of claim 1,
The coordinates in the radial direction are normalized so that the outermost peripheral coordinate is 1, the central r coordinate is r 0 (= 0), the coordinates of the outer peripheral end point of the m th ring zone counted from the center are r m , the depth or height of the ring-shaped zone is taken as h m, (r m 2 -r m-1 2) / √h m and a maximum of the ring-shaped zone, (r m 2 -r m- 1 2 ) / √h m is in the set of annular second largest, the optical component, wherein the step is provided in the optical axis direction.
The optical component of claim 1,
A step in the optical axis direction between the innermost annular zone and the i-th annular zone counted from the center is d 1i , and light from the innermost annular zone and the j-th annular zone counted from the center An optical component characterized in that when the step in the axial direction is expressed as d 1j, the direction of the step is not reversed in any combination of (d 1i , d 1j ).
The optical component of claim 1,
An optical component characterized in that the absolute value of the step d mm + 1 between the m-th annular zone counted from the center and the (m + 1) -th annular zone counted from the center increases monotonously as m increases.
The optical component of claim 1,
The coordinates in the radial direction are normalized so that the outermost coordinate is 1, the r coordinate r 0 (= 0) of the center, the coordinates of the outer peripheral end point of the m-th ring zone counted from the center are r m , represents the depth or height of the strip and h m, when as the M-th of the annular zone counted from the (r m 2 -r m-1 2) / √h m centered maximum of the ring-shaped zone , A step dij in the optical axis direction between the i-th ring zone counted from the center and the j-th ring zone counted from the center,
| D ij |> | h M · {(r j 2 + r j−1 2 ) − (r i 2 + r i−1 2 )} / {r M−1 · (r M −r M−1 )} |
An optical component characterized in that there is at least one set of (i, j).
The optical component according to claim 7,
(R m 2 -r m-1 2 ) / √h It is assumed that the ring zone with the largest m is the M-th ring zone counted from the center, and (r m 2 -r m-1 2 ) / √ when the ring-shaped zone large h m is the second is that the N-th of the annular zone counted from the center, step d NM in the optical axis direction in this set of ring-shaped zone,
| D NM |> | h M · {(r M 2 + r M−1 2 ) − (r N 2 + r N−1 2 )} / {r M−1 · (r M −r M−1 )} |
An optical component characterized by
The optical component of claim 1,
(R m 2 -r m-1 2 ) / √h In the set of the ring zone having the smallest m and (r m 2 -r m-1 2 ) / √h m having the second smallest ring zone An optical component having no step in the optical axis direction.
The optical component of claim 8,
In all (i, j) pairs, the step d ij in the optical axis direction is
| D ij |> | h M · {(r j 2 + r j−1 2 ) − (r i 2 + r i−1 2 )} / {r M−1 · (r M −r M−1 )} |
An optical component characterized by
An imaging device including a plurality of annular zones defined by a plurality of concentric circles and including an optical component configured to be rotationally symmetric with respect to the center of the concentric circles,
The annular zone has a concave or convex surface in a cross-sectional shape in a direction perpendicular to the concentric circle and passing through the center of the concentric circle,
An imaging apparatus comprising: the optical component in which a position of the surface of one of the plurality of annular zones and a position of the surface of another annular zone are different in a direction perpendicular to the concentric circle.
The imaging device according to claim 11,
An imaging apparatus comprising the optical component having a convex cross section of the annular zone.
The imaging apparatus according to claim 12, wherein
An imaging apparatus comprising the optical component having a concave cross-sectional shape of the annular zone.