JP7281064B2 - Light irradiation device, imaging device, and laser processing device - Google Patents

Description

The present invention relates to a light irradiation device that emits phase-controlled light from a plurality of light guide paths, and an imaging device and a laser processing device incorporating the same.

As a light irradiation device, there is an optical phased array (OPA) that forms a desired light beam pattern by emitting light whose phase is controlled from light emission points arranged on equally spaced grid points. (For example, Non-Patent Document 1).

However, when the light emitting points are arranged on equally spaced grid points, the spatial frequency components derived from the light emitting points at short distances in the light beam pattern become dominant, and the number of light emitting points increases. The resolution of the beam pattern cannot be increased.

Regarding antennas for receiving radio waves, a linear array arrangement is being considered for reducing redundancy and uniforming sensitivity to spatial frequencies (Non-Patent Document 2).

"Large-scale nanophotonic phased array" J. Sun, et al., Nature, 493, 195 (2013). "Minimum-Redundancy Linear Arrays" Alan T. Moffet, IEEE Transactions on Antennas and Propagation Vol. AP-16, No. 2, (Mar. 1968).

An object of the present invention is to provide a light irradiation device capable of increasing the resolution of a light beam pattern according to the number of light emission points, and an imaging device and a laser processing device incorporating the same.

A light irradiation device for achieving the above object includes a plurality of light guide sections that allow light to pass therethrough, and a phase adjustment section that adjusts the phase of light emitted from a plurality of exit ports provided in the plurality of light guide sections. The plurality of exit ports are arranged at minimum redundant intervals, and mutual interference of light from the plurality of exit ports forms one wavefront.

In the above light irradiation device, since the plurality of exit ports provided in the plurality of light guide portions are arranged at the minimum redundant interval, the light emitted from the plurality of exit ports can be controlled while suppressing an increase in the number of exit ports. The resolution of the combined light beam pattern can be increased.

According to a specific aspect of the present invention, in the above light irradiation device, light is emitted from a plurality of emission ports simultaneously in parallel. In this case, light beam components corresponding to a plurality of combinations selected from a plurality of exit ports can be formed in parallel, and light beams of various patterns can be formed.

According to another aspect of the present invention, the pair of injection port spacings or the set of spacing vectors obtained by extracting all selectable combinations of a pair of exit ports from the plurality of injection ports have a substantially uniform overlap. is set in degrees. In this case, a substantially uniform spatial frequency distribution can be achieved for the light beams emitted from the plurality of exit ports, so the resolution can be effectively improved while suppressing an increase in the number of exit ports.

According to yet another aspect of the invention, the multiple exit port array maximizes spatial autocorrelation with a substantially uniform density for a fixed number of multiple exit ports. In this case, the light beam pattern can be formed with the largest number of achievable resolvable points while minimizing the number of exit ports.

According to yet another aspect of the invention, the plurality of exit ports are arranged in one dimension to form a Golomb ruler. The Golomb ruler arrangement minimizes spacing redundancy.

According to yet another aspect of the invention, the plurality of injection ports are arranged two-dimensionally to form a Costas array. The Costas array minimizes the redundancy of the spacing vectors.

According to yet another aspect of the present invention, the multiple light guides are multiple waveguides. In this case, it becomes easy to manufacture an integrated circuit type light irradiation device, and it is possible to reduce the size and simplify the structure of the light irradiation device.

According to still another aspect of the present invention, the invention further includes a light source section, and a light branching section that branches light from the light source section and causes the light to enter the plurality of light guide sections. In this case, the light irradiation device can be operated by a single light source.

According to still another aspect of the present invention, the apparatus further includes a control device that outputs a control signal to the phase adjustment section to control the combined state of the light emitted from the plurality of emission ports. In this case, the intensity pattern of the light beam output from the light irradiation device can be set to a desired state under the control of the control device.

According to yet another aspect of the invention, the light source section comprises a continuous wave laser or a pulsed laser. In this case, the light beam pattern output from the light irradiation device can be switched at high speed, and illumination, display, processing, and the like can be performed as a series of processes.

In order to achieve the above object, an imaging apparatus according to the present invention includes the above-described light irradiation device, a measurement sensor for detecting the intensity of measurement light from an object illuminated by the light emitted from the light irradiation device, and a measurement sensor. and an information processing unit that performs processing for extracting an image regarding the state of the object from the detection information obtained by.

The imaging apparatus uses a simple but high-resolution light irradiation device, and can perform highly accurate measurement and the like through simplified processing.

According to a specific aspect of the present invention, the imaging apparatus further includes an illumination image sensor that detects an irradiation intensity distribution of light emitted from the light irradiation device, wherein the light irradiation device detects illumination light with a random phase distribution. to inject.

In order to achieve the above object, a laser processing apparatus according to the present invention outputs a control signal to the above-described light irradiation device and a phase adjustment unit to control the combined state of light emitted from a plurality of emission ports. and a controller.

The laser processing apparatus uses a simple but high-resolution light irradiation device, and can perform processing with high accuracy through simplified processing.

According to a specific aspect of the present invention, the laser processing apparatus further includes a light source section and a light branching section that branches light from the light source section and causes the light to enter the plurality of light guide sections.

(A) is a conceptual block diagram for explaining the light irradiation device of the first embodiment, and (B) is a conceptual plane for explaining a light phased array incorporated in the light irradiation device shown in (A). It is a diagram. (A) is a conceptual diagram explaining the arrangement of exit ports of the optical phased array shown in FIG. 1 (B), and (B) is a diagram explaining the autocorrelation of the arrangement shown in (A). (C) is a diagram for explaining the arrangement of the injection ports of the comparative example, and (D) is a diagram for explaining the autocorrelation of the arrangement of the injection ports of the comparative example. FIG. 4 is a conceptual diagram for explaining a minimum redundant interval regarding the arrangement of injection ports; (A) is a diagram illustrating exit ports that are one-dimensionally arranged to form a Golomb ruler array that achieves the minimum redundant spacing; (B) is a two-dimensional array to form a Costas array; It is a figure explaining the injection port which is set. FIG. 10 is a plan view illustrating a specific one-dimensional arrangement of exit ports, which is an implementation example of a phased array. FIG. 10 is a plan view illustrating a specific two-dimensional arrangement of exit ports, which is an implementation example of a phased array. (A) shows the autocorrelation function of the light irradiation device in a specific embodiment (when the number of exit ports M=12) in which the exit ports are one-dimensionally arranged at the minimum redundant interval of the Golomb rule, and (B) is The autocorrelation function for the equidistant arrangement is shown, and (C) the autocorrelation function for the random arrangement. (A) is a diagram for explaining the formation of a one-dimensional light beam according to a specific embodiment (when M=27), and (B) is a diagram for explaining the achievement of the number of resolution points according to the specific embodiment. be. (A) shows the autocorrelation function of the light irradiation device of the specific embodiment (when M=16) in which the exit ports are two-dimensionally arranged with the first type of minimum redundant spacing, and (B) shows the exit port shows the autocorrelation function of the light irradiation device of the specific embodiment (in the case of M=16) in which is arranged two-dimensionally at the second type of minimum redundant interval, 4 shows the autocorrelation function of the light irradiation device of the comparative example (in the case of M=16). (A) is a diagram for explaining the formation of a light beam according to a specific embodiment (in the case of M=16) in which the exit ports are two-dimensionally arranged with the first type of minimum redundant spacing; FIG. 4C is a diagram for explaining the formation of a light beam according to a specific embodiment (in the case of M=16) in which the ports are two-dimensionally arranged at the second type of minimum redundant interval; =16) is a diagram for explaining the formation of a light beam. It is a conceptual block diagram explaining the phased array etc. which are incorporated in the light irradiation apparatus of 2nd Embodiment. It is a conceptual block diagram explaining the phased array etc. which are incorporated in the light irradiation apparatus of 3rd Embodiment. It is a conceptual block diagram explaining the light irradiation apparatus of 4th Embodiment. It is a conceptual block diagram explaining the light irradiation apparatus of 5th Embodiment. (A) is a diagram for explaining a random injection pattern according to a specific embodiment (when M=16) in which injection ports are arranged one-dimensionally at minimum redundant intervals; It is a figure explaining image reconstruction. (A) is a diagram for explaining the formation of a random pattern according to a specific embodiment (M=16) in which the injection ports are arranged two-dimensionally with the first type of minimum redundant spacing; FIG. 4C is a diagram for explaining the formation of a random pattern according to a specific embodiment (in the case of M=16) in which ports are two-dimensionally arranged at the second type of minimum redundant interval; FIG. 10 is a diagram for explaining the formation of a random pattern in the case of ). It is a conceptual block diagram explaining the light irradiation apparatus of 6th Embodiment.

[First embodiment]
A light irradiation device and the like according to a first embodiment of the present invention will be described in detail below with reference to the drawings.

The light irradiation device 100 of the first embodiment shown in FIG. 1A includes a light source unit 20 that generates laser light B1, and receives the laser light B1 from the light source unit 20 to form irradiation light B2 having a desired wavefront state. and a control device 70 for controlling the operations of the light source unit 20 and the light beam forming unit 30 . The light irradiation device 100 shown in FIG. 1A can be used, for example, as a projector that projects a desired light pattern, and can also be used as a laser processing device that processes an object with an irradiation light pattern.

A light source unit 20 is composed of a coherent light source 21 such as a semiconductor laser, and is accompanied by a light source driving unit 22 which is a light source driving circuit. Laser light B1 set in various wavelength ranges such as an infrared range and a visible range is emitted from the light source unit 20 as, for example, a pulse wave or a continuous wave. When the coherent light source 21 is a pulsed laser, the pulsed laser beam B1 can be emitted from the light source unit 20 with precise timing.

The optical beam forming section 30 has an optical phased array (OPA) 31 and an OPA driving section 32 .

As shown in FIG. 1B, the optical phased array 31 is an optical waveguide type integrated circuit, and includes an optical splitter 31a and a phase adjuster 31b on a substrate 31s. A light input portion 31c for receiving the light and a light output portion 31d for outputting the irradiation light B2 are provided. The optical phased array 31 is capable of switching outputs in a short time of, for example, several tens of microseconds or less, enabling high-speed illumination and processing.

In the optical phased array 31, the optical splitter 31a splits the laser light B1 into M channels and guides them to M waveguides 36, which are M light guides. Although M=8 as an example in FIG. 1B, the value M can be set to any natural number of 3 or more. The waveguides (light guide portions) 36 extend in the Z direction, which is parallel to the XZ plane along which the substrate 31s extends, and are arranged in the X direction orthogonal to the Z direction. As the optical splitter 31a, for example, a star coupler having a slab waveguide, a combination of multistage directional couplers, or the like can be used.

The phase adjustment unit 31b is composed of M electrodes 37a that apply an electric field to waveguides (light guide portions) 36 of M channels, and wiring 37b that enables voltage supply to each electrode 37a. . The electrode 37 a is formed over a predetermined width along the M waveguides 36 . That is, M electrodes 37a are arranged in the X direction. The supply voltage to the wiring 37b is regulated by the OPA driving section 32 shown in FIG. 1A, and can be switched at high speed. By adjusting the voltage applied to each wiring 37b, the phase state of the laser light B1 passing through each waveguide 36 can be individually controlled. Elemental lights whose phase states have been adjusted are emitted simultaneously in parallel from the respective exit ports 38 of the optical phased array 31 that have passed through the phase adjustment section 31b, and illumination synthesized from the individual elemental lights is emitted from the light output section 31d. Light B2 is emitted. That is, the illumination light B2 is a light beam having a desired phase distribution or wavefront distribution in the ±X directions. By controlling the operation of the phase adjustment section 31b via the OPA drive section 32, the illumination light B2 is made into a light beam traveling in a direction forming a desired angle with respect to the Z axis, for example, and the light beam with respect to the Z axis. Scanning within the XZ plane is also possible by increasing or decreasing the angle.

The phase adjustment section 31b is not limited to electro-optic effect type modulation that adjusts the phase by the electric field strength applied to the waveguide 36, but also carrier effect type modulation that adjusts the phase by current injection into the waveguide section. A thermo-optic effect type modulation or the like that adjusts the phase by heating may be used. By utilizing the electro-optical effect, carrier effect, thermo-optical effect, etc., the phase adjustment unit 31b can be made small and inexpensive, reliability can be improved, and phase switching can be speeded up.

In the illustrated example, a lens 100c is arranged to face the optical output section 31d of the optical phased array 31 . The lens 100c has a predetermined focal length. For example, if the light output unit 31d is arranged at the front focal position of the lens 100c, the rear focal position of the lens 100c becomes the Fourier transform plane, and this rear focal point A far-field illumination pattern corresponding to the far-field wavefront pattern of the illumination light B2 emitted from the light output unit 31d can be formed on this illumination surface by using the position as an illumination surface.

The control device 70 has an information processing section 71 , an interface section 72 and a storage section 73 . The information processing unit 71 operates the optical phased array 31 and the like via the interface unit 72, the OPA driving unit 32, and the light source driving unit 22 based on the data including the drive information, the control information, etc., stored in the storage unit 73. illuminating light B2 having a predetermined phase distribution is emitted in a predetermined pattern. Under the control of the control device 70 , the input/output unit 91 presents the operator with various information regarding the operating conditions and operating states of the light irradiation device 100 . An operator inputs an instruction to the control device 70 via the input/output unit 91 . The control device 70 cooperates with the OPA drive section 32 to output a control signal to the phase adjustment section 31b of the optical phased array 31, thereby controlling the combined state of the light emitted from the plurality of emission ports 38. In addition, the composite pattern can be changed at high speed.

By operating the light irradiation device 100 under the control of the control device 70, it is possible to irradiate the object with a laser beam in a desired irradiation pattern and perform laser processing on the surface of the object. Further, by operating the light irradiation device 100 under the control of the control device 70, the surface of the object or the like can be illuminated with a desired irradiation pattern.

The light output portion 31d shown in FIG. 2A is a partial extraction of the light output portion 31d shown in FIG. 1B. The light output unit 31d has a port array 131d composed of, for example, M=8 exit ports 38, and the total array width W of the port array 131d corresponds to the interval between the pair of exit ports 38 on the upper side (+X side) of the drawing. It is larger than M times the minimum width d1. In this case, the original port array 131d on the left side of the drawing and the port array 131d on the right side of the drawing translated by a distance Δx in the −X direction parallel to the arrangement direction form a pair of waveguides at a distance Δx=d1, for example. are aligned coincidentally, but elsewhere the waveguides are not coincident. When the distance Δx is gradually changed, the state in which only a pair of waveguides are aligned is repeated M(M−1)/2 times. As a result, as shown in FIG. 2B, the minimum redundant spacing port array 131d shown in FIG. It has become. In other words, the vertical correlation values are substantially the same over the entire area regardless of the horizontal positional deviation. More specifically, the autocorrelation values are the same except for the peak at Δx=0, which is the most spread state. In the chart of FIG. 2(B), the horizontal axis indicates the distance Δx corresponding to the displacement amount of the parallel movement, and the vertical axis indicates the autocorrelation value.

FIG. 2C is a diagram for explaining the optical output section 31d of the optical phased array 231 of the comparative example. The light output unit 31d of the comparative example is of a conventional uniform arrangement type, and has a port array 231d composed of, for example, M=8 emission ports 38 arranged at regular intervals. The total array width W of the port array 231d is equal to M times the width d2 (=d1) corresponding to the interval between the exit ports 38. As shown in FIG. In this case, the original port array 231d on the left side of the drawing and the port array 231d on the right side of the drawing translated by a distance Δx in the −X direction parallel to the arrangement direction are, for example, M−1 ports at a distance Δx=d. of waveguides are aligned in unison. Gradually changing the distance Δx gradually reduces the number of places where the waveguides are aligned. As a result, as shown in FIG. 2D, the evenly arranged port array 231d shown in FIG. , the autocorrelation is narrow and biased.

FIG. 3 is a diagram illustrating the arrangement of the minimum redundant intervals realized in the optical output section 31d of the optical phased array 31 shown in FIG. 1B from another aspect. The intensity distribution P1 of the near-field output I _NFP (x), which corresponds to the pattern of the illumination light B2 emitted from the plurality of exit ports 38 provided in the light output section 31d, reflects the arrangement of the exit ports 38, resulting in the minimum redundant interval is equivalent to an array of The intensity distribution P2 of the far-sighted output I _FFP (x′) reflects the exit angle of the illumination light B2 from the exit port 38 on the irradiation surface of the rear focal position of the lens 100c. A distribution shape P3 of the spatial spectrum S _FFP (k) obtained by Fourier transforming the intensity distribution P2 of the hyperopia output I _FFP (x′) corresponds to the autocorrelation of FIG. 2(C). In other words, by arranging the exit ports 38 at the minimum redundant intervals, the spatial spectrum distribution shape P3 can be spread over the widest possible band with a uniform density. As a result, the light beam pattern can be shaped to maximize the number of achievable resolution points in situations where the number of exit ports 38 is limited. For example, when the number of exit ports 38 and the free spectral range (FSR) are fixed, finer patterns can be imaged and the spatial resolution can be efficiently improved.

Arranging the plurality of exit ports 38 constituting the light output portion 31d one-dimensionally at the minimum redundant interval is achieved by extracting all combinations of a pair of exit ports 38, 38 that can be selected from the plurality of exit ports 38. A set of obtained intervals of the pair of injection ports 38, 38 (corresponding to a combination realizing discrete distances Δx constituting the horizontal axis of FIG. 2(B)) is set to a substantially uniform degree of overlap. correspond to In this case, the light beams formed by the illumination light B2 emitted from the plurality of exit ports 38 can achieve a one-dimensionally substantially uniform spatial frequency distribution. can be significantly increased.

In the above description, the light output portion 31d constituting the optical phased array 31 is one-dimensional in the X direction, and illumination light B2 having a desired one-dimensional array phase distribution or pattern is emitted from the light output portion 31d. For example, an optical phased array having a structure similar to that of the optical phased array 31 shown in FIG. 1B can be stacked in the Y direction. With such a laminated optical phased array, illumination light B2 having a two-dimensional phase distribution in the XY directions can be formed and emitted. Alternatively, by changing the structure of the waveguide and two-dimensionally arranging the emission port on the XZ plane on the substrate 31s, a structure in which the phase-controlled laser beam is emitted in the direction perpendicular to the main surface of the substrate 31s. can do. Note that even when the light output section 31d includes a plurality of exit ports 38 arranged two-dimensionally in the XY directions (in the XZ direction when taken out in the direction perpendicular to the main surface of the substrate 38), the light output section 31d are two-dimensionally arranged at minimum redundant intervals. When a plurality of two-dimensionally arranged exit ports 38 are arranged at the minimum redundant interval, the light output section 31d or the port array 131d is arranged at a distance of . The positional autocorrelation of the port array 131d before and after the movement is arranged to have a uniform density and a wide band as much as possible when the port array 131d is moved in parallel by Δy.

Strictly two-dimensionally arranging the plurality of exit ports 38 constituting the light output portion 31d at the minimum redundant interval extracts all combinations of selectable pairs of exit ports 38, 38 from the plurality of exit ports 38. A set of interval vectors of the pair of injection ports 38, 38 obtained by this corresponds to being set to a substantially uniform degree of overlap. In this case, the light beams formed by the illumination light B2 emitted from the plurality of exit ports 38 can achieve a two-dimensionally substantially uniform spatial frequency distribution. can be significantly increased.

FIG. 4A is a diagram for explaining a specific technique for one-dimensionally arranging the plurality of exit ports 38 constituting the light output section 31d with the minimum redundant interval. In this case, the set of distances between the pair of injection ports 38, 38 obtained by extracting all the combinations of the pair of injection ports 38, 38 that can be selected from the plurality of injection ports 38 arranged one-dimensionally is the shortest distance , and includes a sequence of increasing elements, 1, 2, 3, 4, 5, and 6, to achieve the minimum redundancy spacing arrangement. The number of injection ports 38 is M=4, but is not limited to this. The arrangement shown in FIG. 4(A) corresponds to the arrangement of the Golomb ruler. That is, the plurality of exit ports 38 forming the light output section 31d are arranged one-dimensionally so as to form a Golomb rule with minimum spacing redundancy. The arrangement at the minimum redundant interval is not limited to a strict Golomb ruler arrangement, and may be an arrangement with some overlap or lack of space between the pair of injection ports 38 . Furthermore, the set of intervals of the injection ports 38 may be not based on a single numerical sequence, but may consist of two or more numerical sequences in which the same values are evenly repeated. are also included in the array at the minimum redundancy interval. Similarly, with respect to the shortest interval as a reference, not only the injection ports 38 are arranged at the exact integer multiple positions, but also the injection ports 38 slightly shifted from the integer multiple positions are arranged at the minimum redundant intervals. include.

FIG. 4B is a diagram for explaining a specific example of two-dimensionally arranging a plurality of exit ports 38 constituting the light output section 31d with a minimum redundant interval. In this case, the sets of spacing vectors of the pair of injection ports 38, 38 obtained by extracting all combinations of the pair of injection ports 38, 38 selectable from the plurality of injection ports 38 arranged two-dimensionally are different from each other. It is a thing. More specifically, the light output unit 31d has M (M=63 in the illustrated example) points arranged on an M×M two-dimensional grid, and one point is arranged in each row. and one point is placed in every column, and considering a set of point-to-point interval vectors (total M×(M−1)/2), all interval vectors are different from each other. It's becoming The arrangement of the exit ports 38 to provide such a set of spacing vectors provides a minimum redundant spacing arrangement. The sequence shown in FIG. 4(B) corresponds to the Costas sequence. That is, the plurality of exit ports 38 forming the light output section 31d are arranged two-dimensionally so as to form a Costas arrangement that minimizes the redundancy of the interval vector. The arrangement at the minimum redundant interval is not limited to a strict Costas rule arrangement, but may be an arrangement in which the spacing vectors of the pair of exit ports 38 are slightly overlapped or the like. It may consist of the above sequence.

FIG. 5 is a plan view illustrating a specific implementation example of the optical phased array 31 having a plurality of exit ports 38 one-dimensionally arranged at minimum redundant intervals. In this case, M=64 waveguides 36 are formed on the substrate 31s, and an optical output section 31d composed of M exit ports 38 arranged at small redundant intervals is formed. The illustration of the optical splitter 31a and the phase adjuster 31b is omitted. FIG. 6 is a plan view illustrating a specific implementation example of the optical phased array 31 having a plurality of exit ports 38 arranged two-dimensionally at minimum redundant intervals.

FIG. 7A is a chart showing the autocorrelation function when M=12 injection ports 38 are arranged one-dimensionally with a minimum redundant interval. In this case, except for the position where the distance Δx corresponding to the positional deviation amount is zero, the density is substantially uniform or the density is as uniform as possible (that is, the substantially uniform density that can be realized, which is recognized as conforming to the uniform density) ) achieves a wide range of autocorrelation distributions. FIG. 7B is a chart showing the autocorrelation function when M=12 injection ports 38 are arranged one-dimensionally at equal intervals. In this case, it can be seen that an uneven and narrow autocorrelation distribution is formed around the position where the distance Δx corresponding to the amount of positional deviation is zero. FIG. 7C is a chart showing the autocorrelation function when M=12 injection ports 38 are randomly arranged one-dimensionally. Here, the distance Δx is randomly arranged in the range of 0.5 to 1.5. Also in this case, it can be seen that an uneven and narrow autocorrelation distribution is formed around the position where the distance Δx corresponding to the positional deviation amount is zero.

FIG. 8A shows the results of a simulation of forming a light beam as the illumination light B2 emitted from the light irradiation device 100 shown in FIG. 1A. In order to form the light beam, the phase adjuster 31b is linearly driven. The horizontal axis indicates the pixel position, and the vertical axis indicates the intensity. The solid line shows the synthesized beam when M=27 exit ports 38 are arranged one-dimensionally with the minimum redundant spacing corresponding to the Golomb ruler, and the dashed line shows the M=27 exit ports 38 arranged on the solid line Golomb ruler. 2 shows the synthesized beams when arranged in one dimension with equal spacing equal to the minimum spacing of . It can be seen that arranging the exit ports 38 at the minimum redundant interval as shown by the solid line can make the beam width extremely narrow and improve the resolution. However, it can be recognized that the noise level becomes high when they are arranged at the minimum redundant interval indicated by the solid line.

FIG. 8B is a diagram for explaining the relationship between the number of exit ports and the number of resolution points. The solid line indicates the number of resolution points that can be formed when the injection ports are one-dimensionally arranged with the minimum redundant interval corresponding to the Golomb ruler, and the dashed line indicates the number of resolution points that can be formed when the injection ports are one-dimensionally arranged at equal intervals. Indicates the number of resolution points. The number of resolution points indicated by the solid line increases in proportion to ^M2 , and the number of resolution points indicated by the dashed line increases in proportion to M2. In other words, it can be said that arranging the injection ports at the minimum redundant interval is overwhelmingly more advantageous than arranging the injection ports at equal intervals. For example, if M = 27 waveguides or exit ports are used and arranged at the minimum redundant spacing, the same number of resolution points can be achieved as if M = 4096 waveguides or exit ports are arranged at equal intervals. It is understood that

FIG. 9A shows the autocorrelation function when M=16 injection ports 38 are two-dimensionally arranged at the first type minimum redundant interval, specifically when two-dimensionally arranged in the Costas arrangement. is a 3D display of the autocorrelation function of . It can be seen that a substantially uniform autocorrelation distribution over a wide range is achieved except for the positions where the distances Δx and Δy corresponding to the amount of positional deviation are zero. FIG. 9B shows the autocorrelation function when M=16 injection ports 38 are two-dimensionally arranged at the second type minimum redundant interval, specifically, the injection ports 38 are arranged in the X direction according to the Golomb ruler. FIG. 11 is a chart showing a 3D display of an autocorrelation function when the arrayed one-dimensional arrays are arranged in a 4×4 (=16) array at intervals of Golomb's rule in the Y direction as well. In the simulation of FIG. 9(B), the irradiation pattern range (FSR) is made equal by matching the minimum arrangement interval of the injection ports 38 with that of FIG. 9(A). In this case, it can be seen that a relatively uniform autocorrelation distribution over a wide range is achieved except for the positions where the distances Δx and Δy corresponding to the amount of positional deviation are zero. However, it can also be seen that regions with regularity are formed in the autocorrelation distribution. FIG. 9C is a chart showing a 3D representation of the autocorrelation function when M=16 injection ports 38 are arranged at regular intervals in a 4×4 two-dimensional array. It can be seen that a nonuniform and narrow autocorrelation distribution concentrated at and near the position where the distances Δx and Δy corresponding to the amount of positional deviation are zero is formed.

FIG. 10A shows the formation of a combined beam when M=16 exit ports 38 are arranged two-dimensionally with the first type of minimum redundancy interval corresponding to the Costas arrangement. In this case, a spot-shaped small-diameter light beam that is repeated at FSR intervals is formed, and it can be seen that high-resolution beam scanning is possible. FIG. 10(B) shows the formation of a composite beam when M=16 exit ports 38 are arranged in a 4×4 two-dimensional array with the second type of minimum redundant spacing that repeats the Golomb rule vertically and horizontally. . In this case, a spot-shaped small-diameter light beam that is repeated at FSR intervals is formed, and it can be seen that high-resolution beam scanning is possible. However, there is a sidelobe-like noise distribution extending vertically and horizontally from the small-diameter light beam. FIG. 10(C) shows the formation of a composite beam when M=16 exit ports 38 are arranged in a 4×4 two-dimensional array at equal intervals. In this case, a blurred thick light beam is formed that is repeated at FSR intervals, and it can be seen that beam scanning cannot be performed with high resolution.

In the light irradiation device 100 of the first embodiment described above, the plurality of exit ports 38 provided in the plurality of waveguides (light guide portions) 36 are arranged at minimum redundant intervals, so the number of exit ports 38 is While suppressing the increase, the resolution of the light beam pattern combining the light emitted from the plurality of exit ports 38 can be improved, and the number of resolution points of the light beam pattern can be increased.

[Second embodiment]
A light irradiation device and the like according to the second embodiment will be described below. The light irradiation device according to the second embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those of the first embodiment.

As shown in FIG. 11, the light beam forming section 30 or the light phased array 231 incorporated in the light irradiation device of the second embodiment has a body portion 230a having the same structure as the light phased array 31 shown in FIG. 1(B). , an optical coupling portion 230b arranged close to the optical output portion 31d of the main body portion 230a, and a multicore bundle fiber 230c arranged close to the optical output portion of the optical coupling portion 230b. The optical coupler 230b is a three-dimensional optical circuit, and can use, for example, a photonic lantern. The optical coupling portion 230b receives, at its light incident portion, illumination light B21, which is a one-dimensional optical signal emitted from the light output portion 31d of the main body portion 230a, and converts the one-dimensional optical signal to illumination light, which is a two-dimensional optical signal. It is converted to B22 and emitted from the optical output section. The multicore bundle fiber 230c receives, at its incident end 3a, the illumination light B22, which is a two-dimensional optical signal emitted from the emitting portion of the optical coupling portion 230b, and a plurality of incident ports formed at the incident end 3a extend from the plurality of incident ports. , and an illumination light B2, which is a two-dimensional optical signal, is emitted from the emission end 3c. The plurality of injection ports 238 formed at the injection end 3c are two-dimensionally arranged at minimum redundant intervals, for example, two-dimensionally arranged at minimum redundant intervals of a second type in which Golomb rulers are repeated vertically and horizontally. there is In the case of this embodiment, the exit ports 38 in the light output portion 31d of the main body portion 230a do not have to be arranged at the minimum redundant interval, and are arranged at regular intervals.

[Third embodiment]
A light irradiation device and the like according to the third embodiment will be described below. Note that the light irradiation device according to the third embodiment is a modification of the first embodiment, and parts that are not particularly described are the same as those in the first embodiment.

In the light irradiation device of the third embodiment, a one-dimensional optical phased array (OPA) is used to form illumination light B2 having a two-dimensional phase distribution.

As shown in FIG. 12, the light beam forming section 30 or the light phased array 331 incorporated in the light irradiation device of the third embodiment has a body portion 330a having the same structure as the light phased array 31 shown in FIG. 1(B). and a prism 330b which is a branching portion arranged on the side of the light output portion 31d of the main body portion 330a and extending along the arrangement direction of the light output portions 31d. The illumination light B2 emitted from the light output section 31d through the waveguide 36 has a phase distribution with respect to the arrangement direction of the light output sections 31d. The illumination light B2 passes through the prism 330b and is deflected in a direction orthogonal to the arrangement direction of the light output portions 31d. At this time, the deflection angle differs depending on the wavelength component of the illumination light B2. Therefore, by sweeping the wavelength of the light source light B12, while scanning the beam in the direction orthogonal to the arrangement direction of the light emitting sections 31d, the desired beam is emitted by the optical phased array 331 in the arrangement direction of the light emitting sections 31d. can be formed. Alternatively, by using a broadband light source, illumination light B2 having a two-dimensional phase distribution divided into wavelength components can be formed.

Instead of using prism 330b, a diffraction grating can also be used. Furthermore, the same effect can be obtained by integrating a diffraction grating type coupler at the location of the light output section 31d and extracting the light in the direction perpendicular to the substrate 31s. Further, instead of using a broadband light source as the light source unit 20, a wavelength tunable light source may be used to sweep the wavelength over time.

[Fourth embodiment]
An imaging apparatus and the like according to the fourth embodiment will be described below. An imaging apparatus according to the fourth embodiment incorporates the light irradiation apparatus according to the first embodiment, and parts that are not particularly described are the same as those in the first embodiment.

As shown in FIG. 13, the imaging apparatus 200 of the fourth embodiment includes an observation optical system 40 for illumination and measurement, and illumination light B2 in addition to the light irradiation apparatus 100 having the structure shown in FIG. and a light receiving element 60 for detecting the intensity of the measurement light B3 from the target OB.

The observation optical system 40 includes a branch mirror 43 and a plurality of lenses L1 and L2. The splitting mirror 43 is a half mirror having uniform transmittance or reflectance. The branching mirror 43 partially transmits the illumination light B2 from the optical phased array 31 to enter the target OB, and reflects the measurement light B3, which is the return light reflected by scattering on the surface OBa of the target OB. to the light receiving element 60. Here, the lens L1 enables illumination in the far-field state while preventing the illumination light B2 emitted from the optical phased array 31 from diverging. Further, the lens L2 forms an image of the measurement light B3 reflected by the target OB on the photosensitive portion 61 of the light receiving element 60. FIG. The light receiving element 60 is a measurement sensor that detects the intensity of measurement light from an illuminated object. The light receiving element 60 has sensitivity to the wavelength of the light source section 20 and can be accompanied by a wavelength selection filter. The light-receiving element 60 is driven by the light-receiving element driving section 82 to operate, and outputs an intensity signal of the measurement light B3 incident on the photosensitive section 61 . Although FIG. 13 shows an example of a system for measuring the reflected light from the target OB, imaging can be similarly performed by measuring the light transmitted through the target OB.

The light irradiation device 100 can operate the light beam forming unit 30 under the control of the control device 70 to two-dimensionally scan, for example, a spot-shaped light beam on the surface OBa of the target OB. The light-receiving element 60 is driven by the light-receiving element driving section 82 under the control of the control device 70 to measure changes over time in the pattern signal of the measurement light B3. The light irradiation device 100 can measure the three-dimensional shape of the target OB from the scanning position and scanning timing of the spot-shaped light beam.

[Fifth embodiment]
An imaging apparatus and the like according to the fifth embodiment will be described below. The imaging apparatus according to the fifth embodiment incorporates the light irradiation apparatus according to the first embodiment, and is a partial modification of the imaging apparatus according to the fourth embodiment. is the same as in the first or fourth embodiment.

As shown in FIG. 14, the imaging apparatus 200 of the fifth embodiment includes, in addition to the light irradiation device 100 having the structure shown in FIG. and a light receiving element 560 for detecting the intensity of the measurement light B3 from the object OB illuminated by the illumination light B2.

From the light output portion 31d of the light phased array 31 of the light irradiation device 100, the illumination light B2 controlled to have a phase state having a random phase distribution is emitted. Furthermore, the illumination light B2 changes in time series at high speed, and the illumination light B2 itself having a random phase distribution is emitted from the light output unit 31d as N different patterns. In other words, these N patterns or N types of illumination light B2 all have random phase distributions and change randomly in time series. In each pattern, the distribution range of random phases is ±180°, and there is no bias.

When the phase adjustment unit 31b constituting the optical phased array 31 is one-dimensional in the X direction, the illumination light B2 having a random phase distribution or pattern in a one-dimensional arrangement is emitted from the light output unit 31d. When the phase adjustment unit 31b is two-dimensional in the XY directions, the illumination light B2 having a random phase distribution or pattern in a two-dimensional array can be emitted from the light output unit 31d.

The observation optical system 40 includes a branch mirror 43 and a plurality of lenses L1, L22, L3. The splitting mirror 43 splits the illumination light B2 from the optical phased array 31 so that part of it enters the target OB and the rest enters the illumination image sensor 50 . Further, the branching mirror 43 reflects and guides the measurement light B3, which is the return light reflected by scattering on the surface OBa of the target OB, to the light receiving element 560. FIG. Here, the lens L1 enables illumination in the far-field state while preventing the illumination light B2 emitted from the optical phased array 31 from diverging. Further, the lens L22 narrows down the beam diameter of the measurement light B3 reflected by the target OB and makes it enter the photosensitive portion 561 of the light receiving element 560 all at once. The lens L3 cooperates with the lens L1 to form a pattern of the illumination light B2 on the photosensitive surface 51 of the illumination image sensor 50 as a far-field image. In the above, the light receiving element 560 collectively detects the intensity of the measurement light reflected by the target OB, and the illumination image sensor 50 detects the far-field image of the illumination light emitted from the optical phased array 31 . Although FIG. 14 shows an example of a system for measuring the reflected light from the target OB, imaging can be similarly performed by measuring the light transmitted through the target OB.

The illumination image sensor 50 is a semiconductor image sensor such as CMOS or CCD. The illumination image sensor 50 is sensitive to the wavelength of the light source section 20 and can be associated with a wavelength selective filter. The illumination image sensor 50 detects the pattern of the illumination light B2 formed on the photosensitive surface 51 and captures it as a detected image. At this time, the intensity value of the illumination light B2 is detected for each pixel position. As described above, since the illumination light B2 is emitted in N patterns by the light phased array 31, N detection images of the illumination light B2 are also obtained.

The control device 70 operates the optical phased array 31 and the like via the interface section 72 and the OPA driving section 32 to emit illumination light B2 having random phase distribution in a plurality of patterns. The information processing section 71 receives the detection image captured by the illumination image sensor 50 through the interface section 72 together with the timing information. The control device 70 receives the intensity of the measurement light B3 detected by the light receiving element 560 together with the timing information via the interface section 72 . The information processing unit 71 temporarily stores the detection image of the illumination light B2 acquired from the illumination image sensor 50 and the intensity value of the measurement light B3 acquired from the light receiving element 560 in the storage unit 73, and stores these detection images and intensity values. The state of the target OB obtained from the values is stored as a measurement result or a reconstructed image. At this time, the information processing unit 71 obtains position information on the illumination image sensor 50 (specifically, coordinates corresponding to the X or XY coordinates on the target OB shown in the drawing and the coordinates corresponding to the Z axis on the illumination image sensor 50). X, etc.), a reconstructed image is calculated from the detection information of the illumination image sensor 50 and the detection information of the light receiving element 560 . This reconstructed image represents the state of the object OB, such as the reflectance of the object OB.

Specifically, the information processing unit 71 changes the phase distribution of the illumination light B2 in the one-dimensional arrangement from the optical phased array 31 in the one-dimensional structure, for example, N times, the total signal intensity detected by the light receiving element 560, A reconstructed image O(x) is calculated from the signal intensity at the target position on the illumination image sensor 50 . This reconstructed image O(x) is most simply
O(x)
=(1/N)×Σ{(S _r −<S>)·I _r (x)} (1)
is given by Here, the value x corresponds to the X-axis on the target OB in the apparatus configuration of FIG. 1, but corresponds to the Z-axis on the illumination image sensor 50. The value x on the illumination image sensor 50 is a discrete value corresponding to a pixel. Also, the value N indicates the number (natural number) of random patterns formed and output by the optical phased array 31 . The value _Sr indicates the measured value of the light receiving element 60, that is, the intensity value of the measurement light B3. The value <S> indicates the average value of N values S _r obtained by N measurements with different random patterns. I _r (x) represents the relationship between the coordinate value x on the illumination image sensor 50 and the intensity value, ie, the detected brightness, at the pixel corresponding to this coordinate value x. Furthermore, Σ means adding (S _r −<S>)·I _r (x) while varying the variable r of the values S _r and I _r (x) from 1 to N. This reconstructed image O(x) gives the luminance value of the reconstructed image for each coordinate value x.

The above equation (1) determines the reconstructed image O(x) with respect to a one-dimensional pixel row in the illumination image sensor 50. The optical phased array 31 has a two-dimensional structure and the illumination image sensor 50 is When acquiring a two-dimensional image, processing is performed to determine a reconstructed image O(x,y) with respect to a two-dimensional pixel array. In this case, the reconstructed image O(x,y) is
O(x, y)
=(1/N)×Σ{(S _r −<S>)·I _r (x, y)} (2)
is given by Here, the value y corresponds to the Y-axis on the object OB and also to the Y-axis on the illumination image sensor 50 .

The above equation (1) or (2) is an example of a technique (ghost imaging) for obtaining a reconstructed image of the target OB from a random illumination pattern, and statistical processing, optimization processing, etc. may be added. Alternatively, another algorithm can obtain the reconstructed image of the object OB.

15A and 15B are charts showing simulation results using the imaging apparatus 200 of the embodiment. In FIG. 15A, the solid line indicates a one-dimensional random illumination pattern obtained by one-dimensionally arranging M=16 exit ports 38 with a minimum redundant interval corresponding to a Golomb ruler. The horizontal axis indicates pixel positions, and the vertical axis indicates irradiation intensity. Note that the dashed line indicates a one-dimensional random illumination pattern achieved by a conventional uniform array, and the waveform is blunted. It can be seen that the optical phased array 31 of the embodiment can form a one-dimensional random illumination pattern very precisely. In FIG. 15B, the solid line corresponds to the solid line in FIG. 15A, and represents a one-dimensional random illumination pattern obtained by arranging M=16 exit ports 38 at the minimum redundant interval of the Golomb ruler. 2 shows a reconstructed image obtained using; The dotted line indicates the original waveform to be restored, and it can be seen that the optical phased array 31 of the embodiment enables extremely precise image reconstruction. The dashed line corresponds to the dashed line in FIG. 15(B) and shows the reconstructed image obtained using random illumination achieved by conventional uniform arrays.

FIG. 16A shows generation of a random pattern when M=16 injection ports 38 are two-dimensionally arranged at the first type minimum redundancy interval corresponding to the Costas arrangement. In this case, a fine random pattern is formed, and it can be seen that image reconstruction with high resolution is possible. FIG. 16(B) shows the formation of a random pattern when M=16 injection ports 38 are arranged in a 4×4 two-dimensional array with the second type of minimum redundant spacing in which the Golomb ruler is repeated vertically and horizontally. . In this case, although coarser than in FIG. 16A, fine random patterns are formed, and it can be seen that image reconstruction with relatively high resolution is possible. FIG. 16(C) shows the formation of a random pattern when M=16 injection ports 38 are arranged at equal intervals in a 4×4 two-dimensional array. In this case, only a rough pattern can be formed, and it can be seen that high-resolution image reconstruction is not easy.

[Sixth embodiment]
An imaging apparatus and the like according to the sixth embodiment will be described below. Note that the imaging apparatus according to the sixth embodiment is a modification of the fifth embodiment, and parts that are not particularly described are the same as those of the fifth embodiment.

In the imaging apparatus of the sixth embodiment, electrodes for operating the optical phased array (OPA) are simplified.

As shown in FIG. 17, an optical phased array 631 used in the imaging apparatus of the sixth embodiment operates M waveguides 36, which are a plurality of optical paths, with fewer electrodes 33e to 33h. In the illustrated example, seven waveguides 36 are operated by four electrodes 33e to 33h. In this case, the values of the voltages V1 to V4 applied to the electrodes 33e to 33h are changed randomly. Thereby, illumination light B2 having a random phase distribution can be emitted from the light output portion 31d.

In the imaging apparatus of the sixth embodiment, the optical phased array 631 is provided with a plurality of electrodes 33e to 33h for phase adjustment that are arranged over the plurality of waveguides 36 and have different random shape patterns. Illumination light B2 with a random phase distribution is emitted depending on how the electrodes 33e to 33h are combined. As a result, the number of electrodes can be greatly reduced without lowering the spatial resolution, the size of the optical phased array 631 can be reduced, and the driving method of the optical phased array 631 can be simplified.

〔others〕
Although the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. For example, the illustrated arrangement of exit ports 38 is merely exemplary, and various arrangements that result in minimal redundant spacing are possible.

The waveguide 36 can be replaced with an optical waveguide such as an optical fiber, and the phase adjustment section 31b can be replaced with an optical phase modulator connected to the optical fiber.

Of the imaging devices 200 of the embodiment, those that acquire three-dimensional images can be used, for example, in the field of LIDAR (Light Detection and Ranging), and can be used to discriminate objects existing in front. Furthermore, the imaging device 200 of the embodiment can also be used in fields such as barcode readers, biological imaging, and microscopes.

3a... Incident end 3c... Ejection end 20... Light source unit 21... Coherent light source 22... Light source drive circuit 30... Light beam forming unit 31... Optical phased array 31a... Optical branching unit 31b... Phase adjusting unit 31c... Optical input section 31d... Optical output section 32... Driving section 36... Waveguide 36... Each waveguide 36... Waveguide 37a... Electrode 37a... Each electrode 37a... Electrode 37b... Wiring , 37b... each wiring, 31s... substrate, 38... exit port, 40... observation optical system, 43... branching mirror, 44... th, 50... illumination image sensor, 51... photosensitive surface, 60... light receiving element, 61... photosensitive section 70... Control device 71... Information processing unit 72... Interface unit 73... Storage unit 81... Driving unit 82... Light receiving element driving unit 91... Input/output unit 100... Light irradiation device 100c... Lens, 131d Port array 200 Imaging device B2 Illumination light B21 Illumination light B22 Illumination light B3 Measurement light L1, 22, L3 Lens OB Object OBa Surface

Claims (17)

a plurality of light guides each passing light;
a phase adjustment unit that adjusts the phase of light emitted from the plurality of emission ports provided in the plurality of light guides;
The plurality of injection ports are arranged at minimum redundant intervals ,
A light irradiation device that forms one wavefront by mutual interference of light from the plurality of exit ports . 2. The light irradiation device according to claim 1, comprising an optical system that forms a far-field image facing said plurality of exit ports . 2. The light irradiation device according to claim 1, wherein a spot beam is formed by mutual interference of light from said plurality of exit ports. 4. The light irradiation device according to any one of claims 1 to 3 , wherein light is emitted from the plurality of emission ports simultaneously in parallel. The interval between the pair of injection ports or a set of interval vectors obtained by extracting all the combinations of the pair of injection ports that can be selected from the plurality of injection ports is set to a substantially uniform degree of redundancy. Item 5. The light irradiation device according to any one of Items 1 to 4 . 6. The arrangement of the plurality of injection ports according to any one of claims 1 to 5 , wherein the spatial autocorrelation is maximized with a substantially uniform density when the number of the plurality of injection ports is fixed. light irradiation device. 6. The light irradiation device according to any one of claims 4 and 5 , wherein the plurality of exit ports are arranged one-dimensionally to form a Golomb ruler. The light irradiation device according to any one of claims 4 and 5 , wherein the plurality of exit ports are two-dimensionally arranged to form a Costas array. The light irradiation device according to any one of claims 1 to 8 , wherein the plurality of light guide portions are a plurality of waveguides. 10. The light irradiation device according to any one of claims 1 to 9 , further comprising: a light source section; and a light branching section for branching the light from the light source section to enter the plurality of light guide sections. 11. The light irradiation device according to claim 10 , further comprising a control device that controls a combined state of the light emitted from the plurality of emission ports by outputting a control signal to the phase adjustment section. 12. The light irradiation device according to any one of claims 10 and 11 , wherein said light source unit has a continuous wave laser or a pulse laser. A light irradiation device according to any one of claims 1 to 12 ,
a measurement sensor that detects the intensity of measurement light from an object illuminated by the light emitted from the light irradiation device;
An imaging apparatus comprising an information processing unit that performs processing for extracting an image regarding the state of a target from detection information obtained by the measurement sensor. The light irradiation device sequentially forms a spot-shaped beam by switching the combination of the plurality of exit ports,
14. The imaging apparatus according to claim 13, wherein said measurement sensor detects the intensity of measurement light from said object according to switching of a combination of said plurality of exit ports.. 14. The imaging apparatus according to claim 13 , further comprising an illumination image sensor for detecting an irradiation intensity distribution of light emitted from said light irradiation device, wherein said light irradiation device emits illumination light having a random phase distribution. A light irradiation device according to any one of claims 1 to 12 ,
and a control device for controlling a combined state of the light emitted from the plurality of emission ports by outputting a control signal to the phase adjustment unit. 17. The laser processing apparatus according to claim 16 , further comprising: a light source section; and a light branching section for branching light from the light source section and causing the light to enter the plurality of light guide sections.

Images