Optical System and Planar Beam Splitting Device

Abstract

The present disclosure relates to an optical system and a planar beam splitting device. An optical system includes: a first curved mirror having an opening or a transmissive portion; a second reflecting portion including a plurality of reflecting surfaces that split a light beam from the opening or the transmissive portion and configured to reflect the light beams obtained by the splitting of the respective reflecting surfaces to respective different positions on the first curved mirror; a third reflecting portion having a plurality of reflecting surfaces that reflect the light beams obtained by the splitting of the second reflecting portion and reflected on the first curved mirror; and a fourth reflecting portion having a plurality of reflecting surfaces that reflect the light beams from the third reflecting portion. The number of reflecting surfaces of each of the third reflecting portion and the fourth reflecting portion is the same as the number of splits by which the second reflecting portion splits the light beam.

Description

Technical Field

[0001] This exemplary embodiment relates to an optical system and a planar beam splitting device. Background Art

[0002] When analyzing dynamic phenomena in detail, it is very useful to obtain information on wavelength (energy) by performing spectral dispersion on an image simultaneously and over time, and this is important in all fields involving chemical reactions. To perform spectral dispersion on two-dimensional image information simultaneously, the two-dimensional image must be converted into a one-dimensional image because general detectors support images of two dimensions or less, and thus the number of dimensions to which the wavelength information is extended increases. Therefore, a planar splitting optical system is an important element in planar spectral splitting that is performed jointly at substantially the same timing (Japanese Patent Application Laid-Open No. 2012-237647).

[0003] If the original image is split more finely, higher-resolution information can be obtained, but it is not easy to arrange the split images in one dimension in a limited space. Most conveniently, one of the means is to spread a large number of optical fibers over the image portion and perform one-dimensional rearrangement of the optical fibers by utilizing the flexibility of the optical fibers, which is a very excellent method. With this method, higher resolution is achieved by increasing the fine optical fibers. However, the transmittance of the optical fibers is not completely uniform, and since, for example, the polarization state of light changes due to curvature, it is difficult to extract the original light information in a uniform state. An optical fiber generally includes a core portion through which light passes and a cladding portion that causes total reflection, and has an optimal size depending on the wavelength to be transmitted. Therefore, there is no optical fiber that is optimal for a wide wavelength, and it is difficult in principle to perform planar spectral dispersion efficiently in a wide wavelength band. For this reason, a method is available in which the image is spatially split by a plurality of mirrors and the resulting images are rearranged in one dimension. Due to the reflection characteristics of the mirrors, the optical characteristics change slightly, but the restored information is stable and easy. However, even if the number of splits is set to about several tens in consideration of manufacturing processes such as adjustment, since the corresponding mirrors must be arranged extremely precisely in terms of position and accuracy, the structure becomes large in space, resulting in difficulty in incorporating the mirrors into a general apparatus having an equivalent number of splits. A planar splitting optical system is also effective in the case of observing an image with a one-dimensional detector, which is inexpensive and capable of performing high-speed and high-resolution readout without using a two-dimensional detector. Summary of the Invention

[0004] According to one aspect of the present invention, an optical system for splitting a light beam from the side of an object plane includes: a first curved mirror having an opening through which the light beam from the object plane passes or a transmissive portion through which the light beam is transmitted; a second reflecting portion including a plurality of reflecting surfaces for splitting the light beam from the opening or the transmissive portion of the first curved mirror and configured to reflect each light beam obtained by the splitting by the respective reflecting surfaces to different corresponding positions on the first curved mirror; a third reflecting portion having a plurality of reflecting surfaces, each reflecting surface reflecting the light beam obtained by the splitting by the second reflecting portion and reflected on the first curved mirror; and a fourth reflecting portion having a plurality of reflecting surfaces for reflecting the light beam from the third reflecting portion. The number of reflecting surfaces of each of the third reflecting portion and the fourth reflecting portion, on which the light beam from the first curved mirror is incident, is the same as the number of splits of the light beam by the second reflecting portion. The respective light beams reflected by the first curved mirror are reflected by the third reflecting portion and the fourth reflecting portion for image formation, such that a split image of the object plane is formed.

[0005] Other features of the present invention will become clear from the following description of exemplary embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a view illustrating an optical system according to a first exemplary embodiment.

[0007] Figures 2A to 2C are views each illustrating the configuration of the second reflecting portion.

[0008] Figure 3 is a view of the optical system according to the first exemplary embodiment as observed from the side of the first reflecting portion.

[0009] Figure 4 is a bird's-eye view of the optical system according to the first exemplary embodiment.

[0010] Figure 5 is a view illustrating the configuration of the third reflecting portion.

[0011] Figure 6 is a view illustrating an optical system according to a second exemplary embodiment.

[0012] Figure 7 is a schematic diagram of a planar beam splitter device. DETAILED DESCRIPTION

[0013] Hereinafter, preferred exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014] First, a first exemplary embodiment of the present invention will be described. Figure 1A view showing the field splitting optical system 100 of the first exemplary embodiment is illustrated. The field splitting optical system 100 is an optical system that splits a light beam from the side of the object plane. As Figure 1 illustrated, the field splitting optical system 100 generally includes four sets of mirrors in sequence from the incident direction of the incident light beam to be split. The field splitting optical system 100 includes a first reflection part 1, a second reflection part 2, a third reflection part 3, and a fourth reflection part 4.

[0015] The first reflection part 1 is a curved mirror having a curved reflecting surface, and is provided with an opening through which the light beam from the object plane passes or a transmission part 1a through which the light beam is transmitted. For example, the opening is a cavity, and the transmission part 1a is formed of a transparent optical member. The first reflection part 1 is, for example, a rotationally symmetric concave mirror.

[0016] The second reflection part 2 has a plurality of reflecting surfaces (mirrors) 2a that reflect the light beam passing through the opening or the transmission part 1a of the first reflection part 1 in different directions depending on the position. In other words, the reflecting surfaces 2a split the incident light into light beams by reflecting the incident light to different positions on the reflecting surface of the first reflection part 1. Each of the reflecting surfaces of the second reflection part 2 is a mirror having a rectangular outer shape and is arranged without a gap on the plane on which the incident light forms an image.

[0017] Figures 2A to 2C Each shows the configuration of the second reflection part. As Figure 2A illustrated, the second reflection part 2 is supported by a support frame. Figure 2B is a front view of the second reflection part 2, and as viewed from the front, the plurality of reflecting surfaces 2a are integral. Figure 2C is a view of the second reflection part 2 when viewed obliquely, and each of the plurality of reflecting surfaces 2a faces a different direction.

[0018] All of the incident light beams to be split are reflected by the corresponding reflecting surfaces 2a of the second reflection part 2 in different directions, and then are reflected by the first reflection part 1. At this time, since each rectangular reflecting surface 2a distributes the split light isotropically, the isotropically split reflected light is incident on the reflecting surface of the first reflection part 1, as Figure 3 illustrated. In the first reflection part 1, the light is incident on Figure 3 the positions indicated by the circles in. In other words, the light beams obtained by the splitting of the second reflection part 2 are incident on each of the regions into which the reflecting surface of the first reflection part 1 is divided by two axes 1b and 1c perpendicular to the rotational symmetry axis of the first reflection part 1.

[0019] The second reflection part 2 is arranged such that its center lies on the optical axis passing through the opening or the transmission part 1a of the first reflection part 1. A plurality of mirrors (reflective surfaces) of the third reflection part 3 and the fourth reflection part 4 are arranged around the central axis, where the optical axis of the first reflection part 1 serves as this central axis. In other words, the central axes of the first reflection part 1, the second reflection part 2, the third reflection part 3, and the fourth reflection part 4 are coaxially arranged. With this configuration of the optical system 100, the isotropic space with the incident light beam as the axis can be utilized spatially, and a reduced size can be achieved.

[0020] The third reflection part 3 is a mirror group including a plurality of mirrors (reflective surfaces) 3a, and reflects the light reflected by the second reflection part 2 and the first reflection part 1. The number of mirrors 3a of the third reflection part 3 onto which the light from the first reflection part 1 is incident is the same as the number of divisions of the light beam by the second reflection part 2.

[0021] The fourth reflection part 4 is a mirror group including a plurality of mirrors (reflective surfaces) 4a, and reflects the light from the third reflection part 3. The number of mirrors 4a of the fourth reflection part 4 onto which the light from the first reflection part 1 is incident is the same as the number of mirrors 3a of the third reflection part 3. Each mirror 4a of the fourth reflection part 4 is a curved mirror. An image converged and one-dimensionally (linearly) arranged by the mirrors 4a of the fourth reflection part 4 is formed in the image reformation region. In other words, the light beam reflected by the first reflection part 1 is reflected by the third reflection part 3 and the fourth reflection part 4 for image formation, such that a divided image of the object plane is formed at the image reformation position 5 on a predetermined plane.

[0022] Each mirror of the third reflection part 3 has a flat surface, and each mirror of the fourth reflection part 4 has a spherical surface, but it can be reversed. In other words, either the plurality of mirrors of the third reflection part or the plurality of mirrors of the fourth reflection part has a flat surface, while the other has a curved surface.

[0023] The mirror surfaces of each of the second reflection part 2, the third reflection part 3, and the fourth reflection part 4 face different directions.

[0024] Figure 4 A bird's-eye view of the optical system 100 is illustrated, and the optical paths reflected by the respective reflection parts are illustrated. The first reflection part 1 has an opening in the central part, and the mirrors are arranged such that the light divided by the second reflection part 2 does not overlap with the mirrors of each of the third reflection part 3 and the fourth reflection part 4. The second reflection part 2 is integrally formed to fill the image plane part of the incident light.

[0025] Figure 5Illustrated is the configuration of the third reflection part. The mirrors 3a of the third reflection part 3 are each formed on a physically integrated structure, but openings 3b are provided in the part through which the light beam passes. Similarly, the mirrors 4a of the fourth reflection part 4 are formed on a physically integrated structure, but openings are provided in the part through which the light beam passes.

[0026] The first reflection part 1, the second reflection part 2, the third reflection part 3, and the fourth reflection part 4 have an isotropic structure centered on the incident light beam axis, and by simply arranging these reflection parts at a desired interval, a planar beam splitting optical system can be easily assembled without any adjustment mechanism.

[0027] As is clear from Figure 1 the light beam flight cross-sectional view of, the space is used as densely as possible to rearrange the image, and also the flight distance and mirror configuration in the space are controlled, thereby achieving reduced size and very efficient planar splitting while providing high resolution.

[0028] Next, a second exemplary embodiment of the present invention will be described. In this exemplary embodiment, the relative positions of the second reflection part 2 and the fourth reflection part 4 are different from those in the first exemplary embodiment. Figure 6 Illustrated is an optical system 200 according to this exemplary embodiment. As Figure 6 illustrated in, the fourth reflection part 4 is arranged on the front side (the side closer to the first reflection part) of the second reflection part 2. Therefore, the fourth reflection part 4 is arranged in front of and near the rear of the second reflection part 2, and thus, the second reflection part 2 and the fourth reflection part 4 can be formed on an integrated structure.

[0029] Next, a planar beam splitting device using the optical system according to the above exemplary embodiment will be described.

[0030] Figure 7 Illustrated is a schematic diagram of a planar beam splitting device 500. The planar beam splitting device 500 causes a light beam to be spectrally dispersed to be incident on an optical system 501 according to the above exemplary embodiment, performs one-dimensional rearrangement of the light beam by planar splitting, and then performs planar spectral dispersion via an image forming mirror 502, a beam splitting element 503, and a detection unit 504. The light to be spectrally dispersed is, for example, infrared light.

[0031] In the planar beam splitting device 500, an image forming mirror 502 that is an off-axis parabolic mirror is used to reflect the light beam from the planar splitting optical system 501 to a beam splitting element 503 that is, for example, a diffraction grating. The light beam spectrally dispersed and spread on a plane by the beam splitting element 503 is incident on the parabolic mirror again through diffraction, and an image is formed on a detection unit 504 having a two-dimensional detector. Thus, a result of a spectrally dispersed image plane can be obtained.

[0032] In order to obtain the original image for each wavelength, the spectral image in the form of the original image can be obtained by rearranging the one-dimensional image of the desired wavelength on the two-dimensional detector according to the segmentation rule.

[0033] Although the preferred exemplary embodiments of the present invention have been described above, the present invention is not limited to these exemplary embodiments, and various modifications and changes can be made within the scope of the gist of the present invention.

[0034] According to the above exemplary embodiments, a planar spectroscopic device advantageous for size reduction, high resolution, or high efficiency can be provided.

[0035] Although the present invention has been described with reference to the exemplary embodiments, it is to be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims should be given the broadest interpretation so as to cover all such modifications as well as equivalent structures and functions.

Claims

1. An optical system, characterized in that, the optical system divides a light beam from an object plane, and the optical system includes: a first curved mirror having an opening through which the light beam from the object plane passes or a transmissive portion through which the light beam is transmitted; a second reflective portion including a plurality of reflecting surfaces that divide the light beam from the opening or the transmissive portion of the first curved mirror and configured to reflect each light beam obtained by the division by the respective reflecting surfaces to respective different positions on the first curved mirror; a third reflective portion having a plurality of reflecting surfaces, each of the plurality of reflecting surfaces reflecting the light beam obtained by the division by the second reflective portion and reflected on the first curved mirror; and a fourth reflective portion having a plurality of reflecting surfaces that reflect the light beam from the third reflective portion, wherein the number of reflecting surfaces on each of the third reflective portion and the fourth reflective portion onto which the light beam from the first curved mirror is incident is the same as the number of divisions by which the second reflective portion divides the light beam, wherein the respective light beams reflected by the first curved mirror are reflected by the third reflective portion and the fourth reflective portion for image formation such that a divided image of the object plane is formed, and wherein the fourth reflective portion is disposed near the front and the rear of the second reflective portion.

2. The optical system according to claim 1, wherein, the central axes of the first curved mirror, the second reflective portion, the third reflective portion, and the fourth reflective portion are coaxially arranged.

3. The optical system according to claim 1, wherein, each reflecting surface of the second reflective portion has a rectangular shape.

4. The optical system according to claim 1, wherein, the first curved mirror is a rotationally symmetric concave mirror, and in the first curved mirror, the light beam obtained by the division by the second reflective portion is incident on each of the regions into which the first curved mirror is divided by two axes perpendicular to the rotation axis.

5. The optical system according to claim 1, wherein, one of the plurality of reflecting surfaces of the third reflective portion and the plurality of reflecting surfaces of the fourth reflective portion is a flat surface and the other is a curved surface.

6. The optical system according to claim 1, wherein, at least one of the second reflective portion, the third reflective portion, and the fourth reflective portion integrally forms each reflecting surface.

7. The optical system according to claim 1, wherein, each light beam reflected by the first curved mirror is reflected by the third reflective portion and the fourth reflective portion to form an image in which the divided images are linearly arranged in a predetermined direction.

8. A planar beam splitting device, characterized in that, the planar beam splitting device includes: the optical system according to claim 1; a beam splitting element configured to spectroscopically disperse the light from the optical system; and a detection unit configured to detect the light spectroscopically dispersed by the beam splitting element.

9. The planar optical splitting device according to claim 8, wherein, the infrared light is spectrally dispersed.

Images