Patent Description:
Patent Document <NUM> discloses an optical system having a scanning device that scans in two directions. It is described that this optical system transmits a scanned laser using a mirror. When the laser is transmitted using the mirror, since there is a layer of air between mirrors, it is difficult to reduce the size of the optical system.

Patent Document <NUM> discloses a prism, and a two-dimensional scanning optical system and an image display device using the same. The prism is equipped with a second incident surface on which laser light as reflected light of a vertical scanner is made incident, a second exit surface through which the laser light incident in the prism from the second incident surface is transmitted toward the vertical scanner, all optical components which constitute a second relay optical systems from the vertical scanner to a horizontal scanner, i.e. optical elements, guiding the laser light so that the laser light made incident from the second incident surface is emitted from the second projection surface.

Patent Document <NUM> discloses an information processing device that acquires a plurality of ledger sheets having the same layout, compares the contents of each column at the same position each of the acquired plurality ledger sheets having the same layout, discriminates the type of each column according to the comparison result, and stores the information on the type of each column in a storage unit. Moreover, the information processing device acquires position information of a processing target ledger sheet, compares information on the type of a column and the content of each column using information on a registered style with respect to the acquired ledger sheet, discriminates the type of each column of the processing target ledger sheet according to the comparison result, and specifies style candidates of the processing target ledger sheet on the basis of the discrimination result.

Patent Document <NUM> discloses a two-dimensional optical scanner in which distortions upon scanning can be reduced in simplified construction and a compact, energy-saving image display system using the same. The two-dimensional optical scanner comprises a light source, a scanner unit of gimbal structure for scanning a light beam therefrom in a two-dimensional direction and a scanning optical system comprising a non-rotationally symmetric surface having an action of correction of a distortion upon scanning of the scanned light beam. The scanning optical system comprises a decentered prism comprising an entrance surface, a first reflecting surface, a second reflecting surface and an exit surface. The respective surfaces of the prism are located such that in that prism, a light beam from the entrance surface toward the first reflecting surface crosses a light beam from the second reflecting surface toward the exit surface. At least one of the entrance surface, first reflecting surface, second reflecting surface and exit surface comprises a non-rotationally symmetric surface.

Patent Document <NUM> discloses an image display apparatus having a light source, a scanning member for deflecting a light from the light source to scan a predetermined surface with the light to form a two-dimensional image thereon, a first optical system for guiding a light deflected by the scanning member to the predetermined surface and a second optical system for guiding a light from the two-dimensional image formed onto the predetermined surface to an observer. There exists, in optical paths of the first optical system and the second optical system, a common optical element with a plurality of optical surfaces including refractive surfaces and reflective surfaces formed on a same medium and the first optical system and the second optical system share a part of optical surfaces of that optical element.

When a space between mirrors is filled with medium of prism, an optical system can be downsized, but further downsizing has been required.

The present disclosure provides a downsized optical system using the prism.

An optical system according to the present disclosure is defined in claim <NUM>.

An optical system of the present disclosure can provide a downsized optical system using a prism.

Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, unnecessarily detailed description may be omitted. For example, a detailed description of a well-known matter and a repeated description of substantially the same configuration may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding of those skilled in the art.

Note that the inventor (s) provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and does not intend to limit the subject matter described in the claims by the accompanying drawings and the following description.

The first embodiment will be described below with reference to <FIG>. In the present embodiment, as illustrated in <FIG>, for example, an X direction is a long diameter direction of a pupil diameter 11a of a laser light R emitted from a laser element <NUM>, and a Y direction is a short diameter direction of the pupil diameter 11a of the laser light R emitted from the laser element <NUM>. The X direction and the Y direction are orthogonal to each other, and a direction orthogonal to an XY plane is a Z direction.

<FIG> is a cross-sectional view illustrating a configuration of an optical system <NUM> according to the present disclosure. The optical system <NUM> includes a laser element <NUM>, a first scanning element <NUM>, a prism <NUM>, and a second scanning element <NUM>.

The laser element <NUM> is, for example, a semiconductor laser. The laser light R emitted from the laser element <NUM> is a parallel light having different pupil diameters in the X direction and the Y direction. For example, as illustrated in <FIG>, the pupil diameter 11a of a laser light R immediately after irradiation from the laser element <NUM> has an elliptical shape extending in the X direction. The laser light R emitted from the laser element <NUM> is scanned in the X direction by the first scanning element <NUM> and is incident on an incident surface 15a of the prism <NUM>. The laser light R has a plurality of wavelengths (wavelength regions) so as to have, for example, colors of red (R), green (G), and blue (B). The laser element <NUM> may emit one light flux in which R, G, and B lights are mixed as the laser light R, or may sequentially emit the laser light R of a light flux of each color.

As illustrated in <FIG>, the first scanning element <NUM> scans the incident laser light R in the X direction as the first direction. The first scanning element <NUM> is, for example, a mirror that is rotationally driven by piezoelectric driving in the Y direction as a rotation axis. The first scanning element <NUM> is, for example, a scanner in a vertical direction. As a result, the parallel light is diffused in the X direction.

The prism <NUM> has the incident surface 15a and an exit surface 15d. The prism <NUM> further has one or more reflecting surfaces in an optical path from the incident surface 15a to the exit surface 15d. In the present embodiment, for example, the prism <NUM> has a first reflecting surface 15b and a second reflecting surface 15c. The prism <NUM> is made of, for example, resin or glass.

The incident surface 15a faces the first scanning element <NUM>, and the laser light R scanned in the X direction by the first scanning element <NUM> is incident on the prism <NUM> through the incident surface 15a. The incident surface 15a and the first reflecting surface 15b face each other, and the laser light R incident from the incident surface 15a is reflected by the first reflecting surface 15b into the prism <NUM>.

As illustrated in <FIG>, the incident surface 15a has a convex shape with respect to the first scanning element <NUM>. The incident surface 15a has a curved surface shape having a curvature along the X direction in which the first scanning element <NUM> scans, and protrudes outward from the prism <NUM>. <FIG> illustrates, as a comparative example, a traveling direction Rv of the laser light R in a case where the incident surface 15a does not have the convex shape. By making the shape of the incident surface 15a the convex shape, the laser light R incident on the incident surface 15a can be refracted inward. As described above, the laser light R scanned in the X direction can travel in the prism in a state that spreading of the laser light R is suppressed, for example, as a light in which the center rays of the scanned laser light are parallel to each other, so that the prism <NUM> can be downsized.

The incident surface 15a may be a rotationally asymmetric surface having a convex shape with respect to the scanning direction of the first scanning element <NUM>.

The incident surface 15a may have a smaller refractive power in the non-scanning direction than in the scanning direction of the first scanning element <NUM>. As a result, chromatic aberration in a non-scanning direction that occurs on the incident surface 15a can be suppressed.

After the laser light R reflected by the first reflecting surface 15b forms an intermediate image, the pupil diameter of the laser light R is enlarged again and reflected again into the prism <NUM> by the second reflecting surface 15c. The laser light R reflected by the second reflecting surface 15c exits from the exit surface 15d to the outside of the prism <NUM>.

The first reflecting surface 15b and the second reflecting surface 15c have different curvatures in the X direction as the first direction and the Y direction as a second direction, respectively. Therefore, the first reflecting surface 15b and the second reflecting surface 15c have a free-form surface shape.

Still more, each of the first reflecting surface 15b and the second reflecting surface 15c may be eccentric to the incident light. This makes it possible to separate the optical path of the incident light without using an optical element such as a beam splitter. Further, each of the first reflecting surface 15b and the second reflecting surface 15c has a concave shape with respect to the incident light.

The exit surface 15d of the prism <NUM> may also have the same configuration as the incident surface 15a. The exit surface 15d may have the convex shape with respect to the second scanning element <NUM>. As a result, the light traveling in the prism <NUM> in a state that spreading of the laser light R scanned in the X direction is suppressed can be condensed on the second scanning element <NUM>, so that the prism <NUM> can be downsized. For example, the exit surface 15d has a curvature along the X direction in which the first scanning element <NUM> scans, and protrudes outward from the prism <NUM>. Note that the curvature in the X direction of the incident surface 15a and the exit surface 15d may have symmetry. In addition, the exit surface 15d may have a curvature along the Y direction in which the second scanning element <NUM> scans, and protrude outward from the prism <NUM>.

Further, the exit surface 15d may have a smaller refractive power in the non-scanning direction than in the scanning direction of the second scanning element <NUM>.

The second scanning element <NUM> scans the laser light R exiting from the exit surface 15d of the prism <NUM> in the Y direction and projects the laser light R onto the projection surface <NUM>. The second scanning element <NUM> is, for example, a mirror that is rotationally driven by piezoelectric driving in the X direction as a rotation axis. The second scanning element <NUM> is, for example, a horizontal scanner. In addition, the second scanning element <NUM> scans in synchronization with the first scanning element <NUM>, so that a two-dimensional image can be projected on the projection surface <NUM>.

In the optical system <NUM> according to the present embodiment, the first scanning element <NUM>, the incident surface 15a of the prism <NUM>, the first reflecting surface 15b of the prism <NUM>, the second reflecting surface 15c of the prism <NUM>, the exit surface 15d of the prism <NUM>, and the second scanning element <NUM> are arranged in order of the optical path from the laser element <NUM>. Therefore, the prism <NUM> is disposed in the optical path from first scanning element <NUM> to second scanning element <NUM>.

As illustrated in <FIG>, the optical system <NUM> has an intermediate imaging position Px in the X direction of a light flux of the laser light R between the first reflecting surface 15b in the prism <NUM> and the second reflecting surface 15c in the prism <NUM>. In other words, the laser light R forms the intermediate image by the first reflecting surface 15b.

Still more, since focal lengths of Rx that is a component of the laser light R in the X direction, and Ry that is a component of the laser light R in the Y direction are also different, the intermediate imaging position Px of the X component Rx and the intermediate imaging position Py of the Y component Ry of the laser light R are different. Further, since focal lengths of the X component Rx and the Y component Ry are different from each other, magnification ratios at the time of emission from the exit surface 15d of the prism <NUM> are also different from each other. In other words, the optical system <NUM> has different optical magnifications in the X direction and the Y direction. For example, in the present embodiment, since the focal length in the Y direction is longer than that in the X direction, the optical magnification in the Y direction is larger than that in the X direction.

The intermediate imaging position Px of the light flux of the laser light R in the X direction does not intersect at the same position with the light flux of the laser light R in the Y direction orthogonal to the X direction. In other words, the intermediate imaging position Px of the X component Rx of the laser light R is not located at the same position as the intermediate imaging position Py of the Y component Ry of the laser light R. As a result, as illustrated in <FIG>, a pupil diameter 11b of the laser light R at the intermediate imaging position Px has a linear shape extending in the Y direction. As a result, it is possible to prevent loss of the pupil diameter 11b of the laser light R when dust or scratch exists at the intermediate imaging position Px.

Further, as illustrated in <FIG>, at the intermediate imaging position Py of the Y component Ry of the laser light R, a pupil diameter 11c of the laser light R exists before the X component Rx of the laser light R forms an image. In this manner, the pupil diameter 11c of the laser light R at the intermediate imaging position Py also has a linear shape extending in the X direction. Since an optical magnification of the optical system <NUM> is larger in the Y direction than in the X direction, a pupil diameter 11d of the laser light R exiting from the exit surface 15d is formed in a circular shape as illustrated in <FIG>.

A relationship between a first exit pupil diameter ϕx1 in the X direction and a second exit pupil diameter cpy1 in the Y direction of the light emitted from the laser element <NUM>, and a first projection pupil diameter ϕx2 in the X direction and a second projection pupil diameter ϕy2 in the Y direction of the light passing through the exit surface 15d of the prism <NUM> and reaching the projection surface <NUM> is as follows: <MAT> By satisfying this relationship, spot sizes at the intermediate imaging positions Px and Py increase, and an influence of dust or scratch inside the prism <NUM> can be effectively reduced.

Next, with reference to <FIG>, it will be described that the optical system <NUM> of the first embodiment reduces chromatic aberration that occurs by the incident surface 15a of the prism <NUM>. <FIG> is a diagram illustrating an intermediate imaging position Pxb of a blue laser light Rb, and <FIG> is a diagram illustrating an intermediate imaging position Pxr of a red laser light Rr. Note that, in <FIG>, the incident surface 15a and the exit surface 15d are illustrated as lenses for simple description.

When the lights of R, G, and B having different wavelengths are made incident from the incident surface 15a having the convex shape, a refractive power varies depending on the wavelength, so that the focal lengths of the lights of the respective wavelengths are different. Hereinafter, the blue laser light Rb and the red laser light Rr having a large wavelength difference will be described. The blue laser light Rb made incident from the incident surface 15a forms the intermediate imaging position Pxb at a position of a focal length fb1. A distance between the intermediate imaging position Pxb and the exit surface 15d is a focal length fb2. In addition, the red laser light Rr made incident from the incident surface 15a forms the intermediate imaging position Pxr at a position of a focal length fr1. A distance between the intermediate imaging position Pxr and the exit surface 15d is a focal length fr2.

The focal lengths fb1 and fr1 determine angles of the light after passing through the incident surface 15a, respectively. Since the refractive power becomes stronger as the wavelength of the light is shorter, the focal length fb1 of the blue laser light Rb is shorter than the focal length fr1 of the red laser light Ra. As a result, chromatic aberration of magnification is likely to occur due to a difference in color. Therefore, the intermediate imaging position Pxb of the blue laser light Rb is located closer to the incident surface 15a than the red intermediate imaging position Pxr.

In the case of an optical system that does not form an intermediate imaging position in the optical path between the first scanning element and the second scanning element, a difference between the focal lengths fb1 and fr1 results in a shift in an angle of incidence on the projection surface <NUM>. As a result, chromatic aberration of magnification occurs. Therefore, the larger the difference between the focal lengths fb1 and fr1, the larger the chromatic aberration of magnification. However, when the intermediate imaging positions Pxb and Pxr are formed in the optical path between the first scanning element <NUM> and the second scanning element <NUM> as in the first embodiment, the chromatic aberration of magnification that occurs on the exit surface 15d acts to correct the chromatic aberration of magnification that occurs on the incident surface 15a. An angle of view on the exit side is determined by a ratio between the focal lengths fb1 and fr1 and the focal lengths fb2 and fr2.

Since the incident surface 15a and the exit surface 15d are the same prism and the same material, a difference between fb1/fb2 and fr1/fr2, which is a difference in the ratio of the focal lengths, is smaller than the difference between fb1 and fr1. As a result, the chromatic aberration of magnification of the light incident on the projection surface <NUM> is reduced, compared with the optical system that does not form the intermediate image in the optical path between the first scanning element and the second scanning element. When the focal length from the incident surface 15a to the intermediate imaging position is equal to the focal length from the intermediate imaging position to the exit surface 15d (fb1 = fb2, fr1 = fr2), the chromatic aberration of magnification is reduced to zero.

In addition, as illustrated in <FIG>, by using the reflecting surfaces 15b and 15c in which chromatic aberration does not occur inside the prism <NUM>, it is possible to correct an influence of other aberrations, such as axial chromatic aberration and field curvature aberration, caused by the difference in refractive power on the incident surface 15a. The laser light R made incident from the incident surface 15a is dispersed into a light of each color due to a difference in refractive power. For example, the blue laser light Rb is refracted more inward than the red laser light Rr. Therefore, the blue laser light Rb and the red laser light Rr are reflected at different positions on reflecting surfaces 15b, 15c. Since the red laser light Rr is reflected at a higher position on the reflecting surfaces 15b and 15c, the red laser light Rr has a larger bending action than the blue laser light Rb. As a result, an angle difference generated on the incident surface 15a can be reduced, and an angle difference of each color of light exiting from the exit surface 15d can be suppressed.

In the present embodiment, the optical system <NUM> has the intermediate imaging position Py in the Y direction. However, as illustrated in <FIG>, the optical system <NUM> may be configured not to have an intermediate imaging action in the Y direction and there is no intermediate imaging position Py. In this case, a curvature of the first reflecting surface 15b may be designed such that the Y component Ry of the laser light R reflected by the first reflecting surface 15b gradually increases.

The present embodiment is configured with a combination of the first scanning element <NUM> that is a scanner in the vertical direction and the second scanning element <NUM> that is a scanner in the horizontal direction. However the present embodiment may be configured with the first scanning element <NUM> that is a scanner in the horizontal direction and the second scanning element <NUM> that is a scanner in the vertical direction. As a result, the size of the incident surface 15a can be reduced.

In the present embodiment, the prism <NUM> has two reflecting surfaces that are the first reflecting surface 15b and the second reflecting surface 15c. However, the prism <NUM> may have only the first reflecting surface 15b or at least two or more reflecting surfaces.

In the present embodiment, the optical system <NUM> includes the laser element <NUM>, the first scanning element <NUM>, the prism <NUM>, and the second scanning element <NUM>, but an optical element having refractive power may be added.

In the present embodiment, the intermediate imaging position Px is formed in the prism <NUM>, but an optical element having a refractive power may be added in an optical path from the laser element <NUM> to the prism <NUM> to form the intermediate imaging position Px outside the prism <NUM>.

As illustrated in <FIG>, an optical path length L1 from the incident surface 15a to the first reflecting surface 15b and an optical path length L2 from the first reflecting surface 15b to the second reflecting surface 15c satisfy a relationship of L1 < L2. According to this configuration, since the optical path length from the first reflecting surface 15b to the second reflecting surface 15c is longer than the optical path length from the incident surface 15a to the first reflecting surface 15b, as illustrated in <FIG>, the incident surface 15a can be disposed closer to the first reflecting surface 15b side (+ Z direction side) than the second reflecting surface 15c, so that the first scanning element <NUM> can also be disposed closer to the first reflecting surface 15b side (+ Z direction side). As a result, the size of the entire optical system <NUM> can be reduced.

The optical system <NUM> according to the first embodiment includes the prism <NUM> having the incident surface 15a, the exit surface 15d, and one or more reflecting surfaces 15b and 15c. In addition, the optical system <NUM> includes the first scanning element <NUM> that scans the incident light in the first direction and reflects the light in the direction of the incident surface 15a of the prism <NUM>, and the second scanning element <NUM> that scans the laser light R exiting from the exit surface 15d of the prism <NUM> in the Y direction orthogonal to the X direction. The incident surface 15a of the prism <NUM> has a convex shape with respect to the first scanning element <NUM>. With such a configuration, when the laser light R scanned in the X direction by the first scanning element <NUM> is incident on the incident surface 15a of the prism <NUM>, the laser light R scanned and diffused is refracted so as to become close to parallel by the incident surface 15a. Therefore, it is possible to suppress spreading of the optical path of the laser light R traveling in the prism <NUM>. As a result, the prism <NUM> can be downsized. In addition, by passing the laser light R through the prism <NUM>, the optical path length can be shortened by the index of the prism <NUM> to downsize the optical system <NUM>.

The optical system <NUM> according to the first embodiment includes the prism <NUM> having the incident surface 15a, the exit surface 15d, and one or more reflecting surfaces 15b and 15c. In addition, the optical system <NUM> includes the first scanning element <NUM> that scans the incident light in the first direction and reflects the light in the direction of the incident surface 15a of the prism <NUM>, and the second scanning element <NUM> that scans the laser light R exiting from the exit surface 15d of the prism <NUM> in the Y direction orthogonal to the X direction. The exit surface 15d of the prism <NUM> has the convex shape with respect to the second scanning element <NUM>. As described above, even when only the exit surface 15d has the convex shape, the light incident on the exit surface 15d from the reflecting surface 15c of the prism <NUM> can converge on the second scanning element <NUM> while being nearly parallel. As a result, the prism <NUM> can be downsized. In addition, by passing the laser light R through the prism <NUM>, the optical path length can be shortened by the index (refractive index) of the prism <NUM> to downsize the optical system <NUM>.

Next, the second embodiment will be described with reference to <FIG>.

<FIG> is a diagram illustrating a configuration of an optical system 1A according to the second embodiment. As illustrated in <FIG>, in the optical system 1A of the present embodiment, the optical system <NUM> of the first embodiment further includes a controller <NUM> that controls the laser element <NUM> to shift a light emission timing of the light of each wavelength for each wavelength in synchronization with scanning by the first scanning element <NUM> and the second scanning element <NUM>. The configuration other than these differences is common between the optical system <NUM> according to the first embodiment and the optical system 1A of the present embodiment.

For example, the laser element <NUM> sequentially emits laser lights Rr, Rg, and Rb of light fluxes of R, G, and B having different wavelengths at different timings. The controller <NUM> controls emission timings of the laser lights Rr, Rg, and Rb of respective colors in synchronization with scanning timings of the first scanning element <NUM> and the second scanning element <NUM>. As a result, it is possible to further reduce deviation of an image projected on the projection surface <NUM> due to chromatic aberration.

Controller <NUM> can be implemented by a semiconductor element or the like. The controller <NUM> can be configured with, for example, a microcomputer, a CPU, an MPU, a GPU, a DSP, an FPGA, or an ASIC. A function of the controller <NUM> may be configured only by hardware, or may be realized by combining hardware and software. The controller <NUM> includes a storage such as a hard disk (HDD), an SSD, and a memory, and realizes a predetermined function by reading data and programs stored in the storage to perform various arithmetic processing.

Since the optical system 1A including the controller <NUM> controls the emission timings of the laser lights Rr, Rg, and Rb of the respective colors according to the scanning timings of the first scanning element <NUM> and the second scanning element <NUM>, it is possible to correct deviation of an image projected on the projection surface <NUM> due to chromatic aberration.

As described above, the first and second embodiments have been described as examples of the technique disclosed in the present disclosure. However, the technique in the present disclosure is not limited thereto, and can also be applied to embodiments in which changes, replacements, additions, omissions, and the like are made. In addition, it is also possible to combine the components described in the first and second embodiments to form a new embodiment.

In the first and second embodiments, the exit surface 15d of the prism <NUM> also has the convex shape, but the present invention is not limited thereto. The exit surface 15d of the prism <NUM> may have a non-convex shape, for example, a flat plate shape as illustrated in <FIG>. As described above, only the incident surface 15a of the prism <NUM> may have the convex shape with respect to the scanning direction of the first scanning element <NUM>. In this case, the second reflecting surface 15c and the exit surface 15d are designed such that the light reflected by the second reflecting surface 15c passes through the exit surface 15d and is condensed on the second scanning element <NUM>.

Furthermore, the size of the prism <NUM> can be adjusted according to the inclination direction of the first reflecting surface 15b with respect to the incident laser light R. <FIG> illustrates a peripheral portion of the first reflecting surface 15b of the prism <NUM>. As illustrated in <FIG>, on a plane including a scanning axis of the first scanning element <NUM> and the laser light R incident on the first reflecting surface 15b, when the first reflecting surface 15b is not inclined with respect to the incident laser light R, the size of the prism <NUM> in the Y direction decreases. For example, when an incident angle θ of the laser light R incident on the first reflecting surface 15b on a YZ plane is <NUM> ° or close to <NUM> °, the size of the prism <NUM> in the Y direction decreases. On the other hand, in this case, as illustrated in <FIG>, on an XZ plane that is a plane orthogonal to the scanning axis of the first scanning element <NUM>, an incident angle Φ on the first reflecting surface <NUM> increases in the scanning direction (X direction) of the first scanning element <NUM>, and thus, the size of the prism <NUM> in the X direction increases.

On the other hand, as illustrated in <FIG>, in the case where the first reflecting surface 15b is inclined with respect to the incident laser light R on a plane including the scanning axis of the first scanning element <NUM> and the laser light R incident on the first reflecting surface 15b, an incident angle θ can be made smaller than the incident angle Φ in <FIG>, so that the size of the prism <NUM> in the Y direction can be suppressed from increasing. For example, as illustrated in <FIG>, when the first reflecting surface 15b is inclined with respect to the incident laser light R on the YZ plane, that is, when the laser light R is reflected at the incident angle θ with respect to the first reflecting surface <NUM> on the YZ plane, an increase in the size of the prism <NUM> in the Y direction can be suppressed. Furthermore, as illustrated in <FIG>, the incident angle Φ on the first reflecting surface <NUM> in the scanning direction (X direction) of the first scanning element <NUM> can be set to <NUM> ° on the XZ plane to reduce the size in the X direction.

In this manner, the first reflecting surface 15b reflects the incident laser light R in a direction orthogonal to the scanning direction (X direction) of the first scanning element <NUM>. By scanning the first scanning element <NUM> in a direction perpendicular to the reflecting direction of the laser light R on the first reflecting surface 15b, the optical system <NUM> can be downsized.

As described above, the embodiments have been described as examples of the technique in the present disclosure. For this purpose, the accompanying drawings and the detailed description have been provided. Therefore, the components described in the accompanying drawings and the detailed description may include not only components essential for solving the problem but also components that are not essential for solving the problem in order to illustrate the above technique. Therefore, it should not be immediately recognized that these non-essential components are essential based on the fact that these non-essential components are described in the accompanying drawings and the detailed description.

Claim 1:
An optical system configured to scan a laser light comprising:
a prism having an incident surface, an exit surface, and one or more reflecting surfaces;
a first scanning element configured to scan the laser light in a first direction, which is a diameter direction of a pupil diameter of the laser light, and reflect the laser light in a direction of the incident surface of the prism; and
a second scanning element configured to scan in a second direction the laser light that exits from the exit surface of the prism, the second direction being orthogonal to the first direction, wherein
the first scanning element, the incident surface, the one or more reflecting surfaces, the exit surface, and the second scanning element are arranged in order of the optical path of the laser light, and
characterized in that
the incident surface of the prism has a convex shape with respect to the first scanning element.