WO2022209554A1 - 発光デバイス及び光源装置 - Google Patents
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/026—Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/11—Comprising a photonic bandgap structure
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- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/32—Holograms used as optical elements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
- H01S5/0425—Electrodes, e.g. characterised by the structure
- H01S5/04256—Electrodes, e.g. characterised by the structure characterised by the configuration
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- H—ELECTRICITY
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- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S2301/00—Functional characteristics
- H01S2301/18—Semiconductor lasers with special structural design for influencing the near- or far-field
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/02—Structural details or components not essential to laser action
- H01S5/028—Coatings ; Treatment of the laser facets, e.g. etching, passivation layers or reflecting layers
- H01S5/0287—Facet reflectivity
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/04—Processes or apparatus for excitation, e.g. pumping, e.g. by electron beams
- H01S5/042—Electrical excitation ; Circuits therefor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
- H01S5/185—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only horizontal cavities, e.g. horizontal cavity surface-emitting lasers [HCSEL]
Definitions
- the present disclosure relates to a light emitting device and a light source device.
- Patent Document 1 discloses a technique for removing 0th-order light contained in the output of an S-iPM (Static-integrable Phase Modulating) laser.
- the light emitting device disclosed in this document comprises an active layer and a phase modulation layer.
- the phase modulation layer includes a base region and multiple modified refractive index regions.
- the plurality of modified refractive index regions have a refractive index different from that of the basic region, and are distributed two-dimensionally in a plane perpendicular to the thickness direction of the phase modulation layer.
- the center of gravity of each modified refractive index region is arranged away from the corresponding lattice point and rotates around the lattice point according to the phase distribution according to the optical image. have an angle.
- the lattice spacing of the square lattice and the emission wavelength of the active layer satisfy the conditions for M-point oscillation.
- the in-plane wavenumber vectors in four directions each include a wavenumber spread corresponding to the angular spread of the optical image.
- the magnitude of at least one of the four in-plane wavevectors is smaller than 2 ⁇ / ⁇ .
- Patent Document 2 discloses a control device for a spatial light modulator.
- This control device includes a lens, a spatial light modulator, an imaging device, a calculation section, an analysis section, and a change section.
- a spatial light modulator has a modulation surface on which a plurality of modulation pixels are two-dimensionally arranged.
- the spatial light modulator presents a first modulation pattern on a modulation surface and outputs a first modulated light to form a first light spot and a second light spot on a pupil plane of the lens.
- An imaging device has an imaging surface in which a plurality of photoelectric conversion pixels are two-dimensionally arranged. The imaging device uses an imaging plane to capture a first fringe pattern image formed on the focal plane of the lens by the first modulated light.
- the imaging device generates first image data representing the light intensity distribution of the first fringe pattern image.
- the calculation unit calculates a first parameter of at least one of intensity amplitude, phase shift amount, and intensity average based on the first image data.
- the analysis unit obtains the relative positional deviation between the optical axis of the lens and the reference coordinates of the modulation surface based on the first parameter.
- the changing unit changes the origin position of the reference coordinates on the modulation plane so as to reduce the deviation of the relative position.
- optical components such as lenses have been used as an optical system for condensing light from the light source.
- the light source can be significantly miniaturized by using, for example, a semiconductor light emitting element.
- it is difficult to reduce the size of optical components for condensing light and this is a factor that hinders the reduction of the size of the light source device.
- An object of the present disclosure is to provide a light emitting device that can reduce the size of a light source device that collects and outputs light, and a light source device that includes the light emitting device.
- a light-emitting device includes a light-emitting portion and a phase modulation layer.
- the phase modulation layer is optically coupled with the light emitting section and includes a basic region and a plurality of modified refractive index regions.
- the plurality of modified refractive index regions have a refractive index different from that of the basic region, and are two-dimensionally distributed within a plane perpendicular to the thickness direction.
- the center of gravity of each modified refractive index region has a first arrangement form or a second arrangement form.
- the center of gravity of each modified refractive index region is arranged away from the corresponding lattice point of the virtual square lattice set in the plane, and is arranged around the lattice point according to a predetermined phase distribution. It has individual rotation angles. The rotation angles of the centers of gravity of at least two modified refractive index regions are different from each other.
- the center of gravity of each modified refractive index region is arranged on a straight line that passes through the lattice points of the square lattice and is inclined with respect to the square lattice. The tilt angles of the plurality of linear square lattices respectively corresponding to the plurality of modified refractive index regions are uniform within the phase modulation layer.
- the distance between the center of gravity of each modified refractive index region and the corresponding lattice point is individually set according to the predetermined phase distribution.
- the distances between the centers of gravity of the at least two modified refractive index regions and the lattice point are different from each other.
- the lattice spacing of the square lattice and the emission wavelength ⁇ of the light emitting portion satisfy the conditions for M-point oscillation.
- Four-direction in-plane wavenumber vectors each including a wavenumber spread corresponding to the angular spread of the emitted light from the light emitting device are formed on the reciprocal lattice space of the phase modulation layer.
- the magnitude of at least one in-plane wavevector is less than 2 ⁇ / ⁇ .
- the predetermined phase distribution includes elements for concentrating emitted light in at least one direction.
- the center of gravity of each modified refractive index region is arranged away from the corresponding lattice point of the virtual square lattice, and has individual rotation angles around the lattice point according to the predetermined phase distribution.
- the center of gravity of each modified refractive index region is arranged on a straight line that passes through a lattice point of a virtual square lattice and is inclined with respect to the square lattice, and the center of gravity of each modified refractive index region and the corresponding lattice point are arranged on the straight line.
- Distances are individually set according to a predetermined phase distribution.
- the lattice spacing of the square lattice and the emission wavelength of the light-emitting portion satisfy the conditions for M-point oscillation. Normally, in the standing wave state of M-point oscillation, light propagating in the phase modulation layer is totally reflected. Therefore, the outputs of both the signal light and the 0th order light are suppressed.
- the signal light is, for example, one or both of +1st order light and -1st order light.
- the standing wave is phase-modulated by the phase distribution on the reciprocal lattice space of the phase-modulating layer, and the in-plane wavenumber vectors in the four directions each including the wavenumber spread corresponding to the angular spread of the emitted light. to form
- the magnitude of at least one of these in-plane wave vectors is 2 ⁇ / ⁇ , that is, smaller than the light line.
- such adjustment of the in-plane wavenumber vector is possible by devising the arrangement of each modified refractive index region.
- the in-plane wave vector When the magnitude of at least one in-plane wave vector is smaller than 2 ⁇ / ⁇ , the in-plane wave vector has a component in the thickness direction of the phase modulation layer and causes total reflection at the interface with air. do not have. As a result, part of the signal light is output from the phase modulation layer. However, when the conditions for M-point oscillation are satisfied, the 0th-order light is not diffracted in the plane-perpendicular direction and is not output from the phase modulation layer into the light line. That is, according to each of the light emitting devices described above, it is possible to remove the zero-order light contained in the output of the S-iPM laser from within the light line and output only the signal light.
- the predetermined phase distribution includes elements for concentrating the emitted light. This allows the light-emitting device to collect and output light.
- the output of 0th-order light that does not contribute to condensing is suppressed, so that only signal light that can contribute to condensing can be output.
- the above element of the predetermined phase distribution may be an element for condensing the emitted light to at least two converging points.
- the above element of the predetermined phase distribution may be an element for condensing the emitted light to at least two converging points.
- the predetermined phase distribution is a combination of a first phase distribution for directing emitted light toward at least two points and a second phase distribution for concentrating the emitted light.
- such an element allows the emitted light to be focused into at least two focal points.
- At least two condensing points may be arranged in a direction intersecting the thickness direction.
- the above-described light-emitting device can be used, for example, for the purpose of interfering light from each condensing point with each other.
- the element of the predetermined phase distribution is an element for concentrating the emitted light to at least four condensing points, and the at least four condensing points may be three-dimensionally distributed.
- the above light-emitting device can be used for purposes such as creating a three-dimensional, in other words, three-dimensional optical image.
- the predetermined phase distribution includes a hologram phase distribution that forms a plurality of bright spots arranged in a first direction, and a lens phase distribution that has a light-collecting action only in a second direction that intersects with the first direction. They may be superimposed. In this case, a striped light image with little luminance unevenness can be obtained. Such an optical image can improve measurement accuracy, for example, in three-dimensional shape measurement.
- the predetermined phase distribution includes a hologram phase distribution forming a plurality of groups of bright spots arranged in a first direction, and a lens phase distribution having a light-collecting action only in a second direction intersecting the first direction. may be superimposed.
- Each luminescent spot group may include a plurality of luminescent spots, and the light intensity of at least two of the plurality of luminescent spots may be different from each other. In this case, a striped light image with little luminance unevenness can be obtained.
- Such an optical image can improve measurement accuracy, for example, in three-dimensional shape measurement.
- each bright spot group may include a first bright spot, a second bright spot, and a third bright spot whose positions in the first direction are different from each other.
- the second bright point and the third bright point are arranged at positions sandwiching the first bright point, and the light intensity of the second bright point and the third bright point is higher than the light intensity of the first bright point. may be smaller. This makes it possible to obtain a light image in which the light intensity increases and decreases sinusoidally along the first direction.
- the predetermined phase distribution may be obtained by superimposing the hologram phase distribution and the lens phase distribution.
- the hologram phase distribution forms a plurality of bright spots aligned in the first direction.
- the lens phase distribution has a focusing effect in a first direction and a second direction intersecting the first direction, and the focal length in the first direction is longer than the focal length in the second direction. In this case, a striped light image with little luminance unevenness can be obtained.
- Such an optical image can improve measurement accuracy, for example, in three-dimensional shape measurement.
- a first light source device includes the first and second light emitting devices that are any of the light emitting devices described above.
- the elements of the predetermined phase distribution of the first light emitting device focus the first outgoing light from the first light emitting device towards a first focus point.
- the elements of the predetermined phase distribution of the second light emitting device focus the second outgoing light from the second light emitting device towards a second focus point aligned with the first focus point.
- This light source device causes the first emitted light and the second emitted light to interfere with each other to generate interference fringes.
- a second light source device includes the above-described light emitting device that collects emitted light to at least two condensing points.
- the elements of the predetermined phase distribution of the light emitting device focus a first outgoing light from the light emitting device to a first focus and a second outgoing light from the light emitting device to a second focus. Concentrate to a point.
- This light source device causes the first emitted light and the second emitted light to interfere with each other to generate interference fringes.
- interference fringes are generated by the first and second emitted lights emitted toward the first and second condensing points, respectively.
- This interference fringe is a light image in which the light intensity increases and decreases sinusoidally along a certain direction.
- Such an optical image can be used, for example, for three-dimensional shape measurement.
- the light-emitting devices included in these light source apparatuses can be miniaturized as described above. Therefore, since it can be placed in an extremely small space such as the body, it becomes possible to perform three-dimensional shape measurement for a small space that has been impossible in the past.
- phase distribution for condensing the emitted light is simpler than the phase distribution for directly generating the optical image including the interference fringes, the noise generated in the optical image during calculation can be reduced. can be done. Therefore, since an optical image having light intensity that increases and decreases sinusoidally can be generated with high accuracy, measurement errors in three-dimensional shape measurement, for example, can be reduced.
- the first light source device may further comprise an optical system optically coupled with the first and second light emitting devices.
- the first light collection point is located between the first light emitting device and the optical system.
- a second light collection point is located between the second light emitting device and the optical system.
- the first emitted light and the second emitted light interfere with each other after passing through the optical system.
- the second light source device may further comprise an optical system optically coupled with the light emitting device.
- the first and second focal points are located between the light emitting device and the optical system. The first emitted light and the second emitted light interfere with each other after passing through the optical system.
- the first and second light source devices may have optical systems.
- a light emitting device capable of miniaturizing a light source device that collects and outputs light, and a light source device that includes the light emitting device.
- FIG. 1 is a partial cross-sectional perspective view showing the configuration of a light emitting device according to an embodiment of the present disclosure.
- FIG. 2 is a schematic diagram showing a laminated structure of a light emitting device.
- FIG. 3 is a plan view of the phase modulation layer.
- FIG. 4 is an enlarged view of a unit configuration area.
- FIG. 5 is a diagram schematically showing how emitted light is output from the light emitting device of one embodiment.
- Part (a) of FIG. 6 is a diagram showing how the condensing points are arranged in a direction intersecting the thickness direction of the light emitting device.
- Part (b) of FIG. 6 is a diagram showing how the condensing points are three-dimensionally distributed. Parts (a) and (b) of FIG.
- FIG. 7 are diagrams showing a comparison between the light emitting device of the embodiment and the S-iPM laser of the comparative example.
- FIG. 8 is a plan view showing an example in which a substantially periodic refractive index structure is applied within a specific region of the phase modulation layer.
- FIG. 9 is a diagram for explaining coordinate transformation from spherical coordinates to coordinates in the XYZ orthogonal coordinate system.
- FIG. 10 is a plan view showing a reciprocal lattice space for a phase modulation layer of a light emitting device that performs M-point oscillation.
- FIG. 11 is a conceptual diagram illustrating a state in which a diffraction vector is added to an in-plane wave vector.
- FIG. 12 is a diagram for schematically explaining the peripheral structure of the light line.
- FIG. 13 is a diagram conceptually showing an example of phase distribution.
- FIG. 14 is a conceptual diagram for explaining a state in which diffraction vectors are added to in-plane wavenumber vectors in four directions from which wavenumber spread is removed.
- FIG. FIG. 17 is a diagram showing an example of the lens phase distribution.
- FIG. 18 is a diagram showing a partially enlarged lens phase distribution.
- FIG. 19 is a diagram showing the results of an experiment in which a light-emitting device according to an embodiment was fabricated and a near-field image was captured while moving the objective lens in the Z direction.
- FIG. 20 is a diagram showing the results of an experiment in which a light-emitting device according to an embodiment was prototyped and a near-field image was captured while moving the objective lens in the Z direction.
- FIG. 21 is a diagram showing the result of similarly imaging a near-field image of a normal light-emitting device (LED) that does not have a phase modulation layer.
- FIG. 22 is a diagram showing how +1st-order light and -1st-order light are emitted from a phase modulation layer of a light-emitting device.
- FIG. 23 is a diagram showing an example of a phase distribution including a lens phase distribution and components corresponding to non-zero vectors.
- FIG. 24 is a conceptual diagram of a method of dividing the hologram phase distribution and the lens phase distribution into a real part and an imaginary part, and performing phase synthesis on each of the real part and the imaginary part.
- Parts (a) and (b) of FIG. 25 are diagrams showing examples of random patterns.
- Parts (a) and (b) of FIG. 26 are diagrams showing positions of condensing points.
- FIG. 27 is a diagram showing a near-field image of the light-emitting device fabricated in the experiment.
- FIG. 28 is a diagram showing a near-field image of the light-emitting device fabricated in the experiment.
- FIG. 29 is a diagram showing a near-field image of the light-emitting device fabricated in the experiment. Parts (a) and (b) of FIG. 30 are diagrams showing positions of condensing points.
- FIG. 31 is a diagram showing a near-field image of the light-emitting device fabricated in the experiment.
- FIG. 32 is a diagram showing a near-field image of the light-emitting device fabricated in the experiment.
- FIG. 33 is a diagram showing a near-field image of the light-emitting device fabricated in the experiment.
- FIG. 34 is a schematic diagram showing the configuration of a three-dimensional measurement system according to the second embodiment.
- FIG. 35 is a diagram schematically showing a light source device as an example of the configuration of the light source device.
- FIG. 35 is a diagram schematically showing a light source device as an example of the configuration of the light source device.
- FIG. 36 is a diagram schematically showing a light source device as another example of the configuration of the light source device.
- FIG. 37 is a diagram showing an interference light image on the imaging plane, that is, a pattern of measurement light.
- FIG. 38 is a schematic diagram partially showing the configuration of a light source device according to a comparative example.
- FIG. 39 is a diagram schematically showing a configuration when the angle ⁇ a of the emission direction is made small.
- FIG. 40 is a schematic diagram partially showing the configuration of a light source device according to a modification. Parts (a) and (b) of FIG. 41 are diagrams for explaining the effect of providing a mask.
- FIG. 42 is a diagram showing an example of a lens phase distribution for condensing light only in one direction. Part (a) of FIG.
- FIG. 43 is a diagram schematically showing an example of a light image formed on one imaginary plane only by the hologram phase distribution.
- Part (b) of FIG. 43 is a diagram schematically showing an optical image obtained by superimposing the lens phase distribution shown in FIG. 42 on the hologram phase distribution forming the optical image shown in part (a).
- FIG. 44 is a far-field image of a striped light image emitted from the prototype light-emitting device.
- FIG. 45 shows a far-field image when a striped optical image is formed only by the hologram phase distribution without using the lens phase distribution.
- Parts (a) and (b) of FIG. 46 conceptually show the operation of forming a striped light image different from that of FIG. Parts (a) and (b) of FIG.
- FIG. 47 are diagrams showing aspects similar to those shown in FIG. FIG. 48 is a far-field image of a striped light image emitted from the prototype light-emitting device.
- Parts (a) and (b) of FIG. 49 show another aspect similar to the aspect shown in FIG.
- FIG. 50 is a far-field image of a striped light image emitted from the prototype light-emitting device.
- FIG. 51 is a diagram showing an example of a lens phase distribution in which the focal length in the X direction is longer than the focal length in the Y direction.
- Part (a) of FIG. 52 is a diagram schematically showing an example of an optical image formed only by the hologram phase distribution, and shows the same optical image as part (a) of FIG. 43 .
- FIG. 52 is a diagram schematically showing an optical image obtained by superimposing the lens phase distribution shown in FIG. 51 on the hologram phase distribution forming the optical image shown in part (a).
- FIG. 53 is a far-field image of a striped light image emitted from the prototype light-emitting device.
- FIG. 1 is a partially cutaway perspective view showing the configuration of a light emitting device 1 according to an embodiment of the present disclosure.
- FIG. 2 is a schematic diagram showing the laminated structure of the light-emitting device 1. As shown in FIG. 1 and 2 define an XYZ orthogonal coordinate system in which the axis extending in the thickness direction of the light emitting device 1 at the center of the light emitting device 1 is the Z axis.
- the light emitting device 1 is a laser light source that forms a standing wave in the XY in-plane direction and outputs a phase-controlled plane wave in a direction intersecting the thickness direction.
- the light-emitting device 1 is an S-iPM laser, and has an arbitrary shape in a direction perpendicular to the main surface 10a of the semiconductor substrate 10, that is, in the Z direction, or in a direction inclined with respect to the Z direction, or in a direction including both. A light image can be output.
- the light emitting device 1 includes an active layer 12 as a light emitting portion provided on a semiconductor substrate 10, a pair of clad layers 11 and 13 sandwiching the active layer 12, and a clad layer 13. and a contact layer 14 provided thereon.
- the semiconductor substrate 10, the clad layers 11 and 13, and the contact layer 14 are composed of compound semiconductors such as GaAs semiconductors, InP semiconductors, or nitride semiconductors.
- the energy bandgap of the clad layer 11 and the energy bandgap of the clad layer 13 are larger than the energy bandgap of the active layer 12 .
- the thickness directions of the semiconductor substrate 10, the clad layer 11, the active layer 12, the clad layer 13, and the contact layer 14 match the Z-axis direction.
- the light-emitting device 1 further comprises a phase-modulating layer 15 optically coupled with the active layer 12 .
- the phase modulation layer 15 is provided between the active layer 12 and the clad layer 13 .
- the thickness direction of the phase modulation layer 15 coincides with the Z-axis direction.
- Phase modulation layer 15 may be provided between cladding layer 11 and active layer 12 .
- An optical guide layer may be provided between the active layer 12 and the clad layer 13 and between the active layer 12 and the clad layer 11, or both, if necessary.
- the optical guiding layers may include carrier barrier layers for effectively confining carriers to the active layer 12 .
- the phase modulation layer 15 includes a basic region 15a and a plurality of modified refractive index regions 15b.
- the basic region 15a consists of a first refractive index medium.
- the plurality of modified refractive index regions 15b are made of a second refractive index medium having a refractive index different from that of the first refractive index medium, and exist within the basic region 15a.
- This wavelength ⁇ 0 is included within the emission wavelength range of the active layer 12 .
- the phase modulation layer 15 can select a band edge wavelength near the wavelength ⁇ 0 from the emission wavelengths of the active layer 12 and output it to the outside.
- the light that has entered the phase modulation layer 15 forms a predetermined mode according to the arrangement of the modified refractive index regions 15b in the phase modulation layer 15, and is emitted from the surface of the light emitting device 1 to the outside as laser light.
- the light-emitting device 1 further includes an electrode 16 provided on the contact layer 14 and an electrode 17 provided on the back surface 10b of the semiconductor substrate 10 .
- Electrode 16 makes ohmic contact with contact layer 14 .
- the electrode 17 makes ohmic contact with the semiconductor substrate 10 .
- the electrode 17 has an opening 17a in the central region of the back surface 10b.
- Electrode 16 is provided in the central region of the surface of contact layer 14 .
- a portion of the contact layer 14 other than the electrode 16 is covered with a protective film 18 (see FIG. 2). Portions of the contact layer 14 that are not in contact with the electrode 16 may be removed to limit the current range.
- a region of the back surface 10b of the semiconductor substrate 10 other than the region where the electrode 17 is provided is covered with an antireflection film 19 including the inside of the opening 17a.
- the anti-reflection film 19 in other regions than the opening 17a may be removed.
- the active layer 12 when a drive current is supplied between the electrodes 16 and 17, recombination of electrons and holes occurs in the active layer 12, causing the active layer 12 to emit light. Electrons and holes that contribute to this light emission and light generated in the active layer 12 are efficiently confined between the clad layers 11 and 13 .
- the light emitted from the active layer 12 enters the phase modulation layer 15 and forms a predetermined mode according to the lattice structure inside the phase modulation layer 15 .
- a part of the laser light emitted from the phase modulation layer 15 is directly output to the outside of the light emitting device 1 through the opening 17a from the rear surface 10b.
- the rest of the laser light emitted from the phase modulation layer 15 is reflected by the electrode 16 and then emitted from the back surface 10b to the outside of the light emitting device 1 through the opening 17a.
- the signal light contained in the laser light is emitted in an arbitrary direction including a direction perpendicular to the main surface 10a and a direction inclined with respect to the direction perpendicular to the main surface 10a.
- the light emitted from the light emitting device 1 is signal light.
- the signal light is mainly 1st-order diffracted light or ⁇ 1st-order diffracted light of laser light, or both.
- the 1st-order diffracted light will be referred to as 1st-order light
- the ⁇ 1st-order diffracted light will be referred to as ⁇ 1st-order light.
- the phase modulation layer 15 of this embodiment suppresses the output of the 0th order light of the laser light.
- the phase modulation layer 15 includes a basic region 15a and a plurality of modified refractive index regions 15b.
- the basic region 15a consists of a first refractive index medium.
- the plurality of modified refractive index regions 15b are made of a second refractive index medium having a refractive index different from that of the first refractive index medium.
- a virtual square lattice is set in the XY plane for the phase modulation layer 15 . One side of the square lattice is parallel to the X-axis and the other side is parallel to the Y-axis.
- Square-shaped unit constituent regions R centered on lattice points O of the square lattice are arranged two-dimensionally over a plurality of columns along the X-axis and a plurality of rows along the Y-axis.
- the XY coordinates of each unit structural region R are defined by the position of the center of gravity of each unit structural region R. These center-of-gravity positions coincide with lattice points O of a virtual square lattice.
- one modified refractive index region 15b is provided in each unit constituent region R. As shown in FIG.
- the planar shape of the modified refractive index region 15b is, for example, circular.
- the lattice point O may be located outside the modified refractive index region 15b, or may be included inside the modified refractive index region 15b.
- FIG. 4 is an enlarged view of the unit configuration region R.
- each of the modified refractive index regions 15b has a center G of gravity.
- ⁇ (x, y) be the angle between the vector from the grid point O to the center of gravity G and the X axis.
- the angle ⁇ (x, y) is the rotation angle around the lattice point O of the center of gravity G of the modified refractive index region 15b.
- x indicates the position of the x-th grid point on the X-axis
- y indicates the position of the y-th grid point on the Y-axis.
- the direction of the vector connecting the lattice point O and the center of gravity G coincides with the positive direction of the X axis.
- the length of the vector connecting the lattice point O and the center of gravity G be r(x, y). In one example, r(x, y) is constant over the entire phase modulation layer 15 regardless of x and y.
- the direction of the vector connecting the lattice point O and the center of gravity G that is, the rotation angle ⁇ is determined for each lattice point O according to the phase distribution ⁇ (x, y) corresponding to the desired shape of the emitted light.
- the rotation angles ⁇ of the centers of gravity G of at least two modified refractive index regions 15b are different from each other.
- such an arrangement form of the center of gravity G is referred to as a first arrangement form.
- the phase distribution ⁇ (x, y) has a specific value for each position determined by the values of x, y, but is not necessarily represented by a specific function.
- the distribution of the rotation angle ⁇ (x, y) is determined by extracting the phase distribution ⁇ (x, y) from the complex amplitude distribution obtained by Fourier transforming the desired shape of the emitted light.
- an iterative algorithm such as the Gerchberg-Saxton (GS) method, which is commonly used in calculations for generating holograms. In this case, it is possible to improve the reproducibility of the beam pattern.
- Parts (a) to (c) of FIG. 5 are diagrams schematically showing how the emitted light Lout is output from the light emitting device 1 of the present embodiment.
- the light-emitting device 1 of the present embodiment performs a self-condensing operation in which the emitted light Lout is emitted in a desired shape while being condensed.
- the number of condensing points U of the emitted light Lout may be one, two, or three or more. good too.
- each condensing point U is arranged in a direction intersecting or orthogonal to the thickness direction of the light emitting device 1, that is, the Z direction, as shown in part (a) of FIG. may be distributed on a plane W that intersects or is perpendicular to the Z direction.
- each condensing point U may be distributed three-dimensionally (stereoscopically) as shown in part (b) of FIG.
- the distribution of the phase distribution ⁇ (x, y) and the rotation angle ⁇ (x, y) is determined according to the distribution of the condensing point U of the emitted light Lout.
- FIG. 7 is a diagram showing a comparison between the light emitting device 1 of this embodiment and the S-iPM laser of the comparative example. As shown in part (a) of FIG. 7, the light emitting device 1 of the present embodiment emits the emitted light Lout while condensing it. On the other hand, the S-iPM laser 100 of the comparative example, as shown in FIG. to form
- FIG. 8 is a plan view showing an example in which a substantially periodic refractive index structure is applied within a specific region of the phase modulation layer 15.
- a substantially periodic structure for emitting a desired light image for example, the structure shown in FIG. 3, is formed inside the square inner region RIN.
- a perfect circular modified refractive index region 15b is arranged in which the lattice point position of the square lattice coincides with the center of gravity position.
- the virtually set grid spacing a of the square grid is the same.
- a substantially periodic structure for emitting a desired optical image for example, the structure shown in FIG.
- the rotation angle ⁇ (x, y) of the modified refractive index region 15b in the phase modulation layer 15 is adjusted by the following procedure. Determine distribution.
- An XYZ orthogonal coordinate system is defined by a Z axis that coincides with the normal direction and an XY plane that coincides with one surface of the phase modulation layer 15 including the multiple modified refractive index regions 15b.
- a virtual square lattice composed of M 1 ⁇ N 1 square-shaped unit structural regions R is set on the XY plane.
- M 1 and N 1 are integers of 1 or more.
- spherical coordinates defined by the length r of the radius vector, the tilt angle ⁇ tilt from the Z axis, and the rotation angle ⁇ rot from the X axis specified on the XY plane Define (r, ⁇ rot , ⁇ tilt ).
- the coordinates ( ⁇ , ⁇ , ⁇ ) in the XYZ orthogonal coordinate system are expressed by the following equations (1) to (3) with respect to the spherical coordinates (r, ⁇ rot , ⁇ tilt ). It is assumed that the specified relationship is satisfied.
- FIG. 9 is a diagram for explaining coordinate transformation from spherical coordinates (r, ⁇ rot , ⁇ tilt ) to coordinates ( ⁇ , ⁇ , ⁇ ) in the XYZ orthogonal coordinate system.
- the coordinates (.xi., .eta., .zeta.) represent a designed optical image on a predetermined plane set in the XYZ orthogonal coordinate system that is the real space.
- the coordinate value kx is a normalized wave number defined by the following equation (4) and is a coordinate value on the K x -axis corresponding to the X-axis.
- the coordinate value ky is a normalized wavenumber defined by the following equation (5), and is a coordinate value on the Ky axis that corresponds to the Y axis and is orthogonal to the Kx axis.
- the normalized wavenumber means a wavenumber normalized by setting the wavenumber 2 ⁇ /a, which corresponds to the lattice spacing of a virtual square lattice, to 1.0.
- the specific wavenumber range including the beam pattern corresponding to the optical image is M 2 ⁇ N 2 image areas FR each having a square shape.
- M 2 and N 2 are integers of 1 or more. Integer M2 need not match integer M1. Integer N2 need not match integer N1. Equations (4) and (5) are, for example, Y.
- the image region FR(kx, ky) is specified by the coordinate component kx in the Kx - axis direction and the coordinate component ky in the Ky-axis direction.
- the coordinate component kx is an integer from 0 to M 2 ⁇ 1.
- the coordinate component ky is an integer from 0 to N 2 ⁇ 1.
- a unit constituent region R(x, y) on the XY plane is specified by a coordinate component x in the X-axis direction and a coordinate component y in the Y-axis direction.
- the coordinate component x is an integer from 0 to M 1 -1.
- the coordinate component y is an integer from 0 to N 1 -1.
- the complex amplitude F(x, y) obtained by performing a two-dimensional inverse discrete Fourier transform on each of the image regions FR (kx, ky) to the unit component region R(x, y) is given by
- the imaginary unit is given by the following equation (6).
- the complex amplitude F(x,y) is defined by equation (7) below, where A(x,y) is the amplitude term and ⁇ (x,y) is the phase term.
- the unit constituent area R(x, y) is defined by the s-axis and the t-axis.
- the s-axis and the t-axis are parallel to the X-axis and the Y-axis, respectively, and are orthogonal to each other at the lattice point O(x, y) that is the center of the unit structural region R(x, y).
- the phase modulation layer 15 is configured to satisfy the following fifth and sixth conditions.
- the fifth condition is that the center of gravity G is separated from the grid point O(x, y) within the unit configuration region R(x, y).
- the sixth condition is that the line segment length r 2 (x, y) from the lattice point O(x, y) to the corresponding center of gravity G is set to a common value in each of the M 1 ⁇ N 1 unit constituent regions R. It is being done.
- the sixth condition is that the angle ⁇ (x, y) formed between the line segment connecting the lattice point O(x, y) and the corresponding center of gravity G and the s-axis satisfies the following relationship: be.
- ⁇ (x,y) C ⁇ (x,y)+B C: constant of proportionality, for example 180°/ ⁇ B: Any constant, for example 0
- FIG. 10 is a plan view showing a reciprocal lattice space for a phase modulation layer of a light emitting device that performs M-point oscillation.
- a point P in the figure represents a reciprocal lattice point.
- the arrow B1 in the figure represents the fundamental reciprocal lattice vector, and the arrows K1, K2, K3, and K4 represent the four in-plane wavevectors.
- the in-plane wavenumber vectors K1 to K4 each have a wavenumber spread SP due to the distribution of the rotation angle ⁇ (x, y).
- the magnitude of the in-plane wavenumber vectors K1 to K4 that is, the magnitude of the standing wave in the in-plane direction is smaller than the magnitude of the fundamental reciprocal lattice vector B1. Therefore, the vector sum of the in-plane wavenumber vectors K1 to K4 and the fundamental reciprocal lattice vector B1 does not become zero. Since the wave number in the in-plane direction cannot be 0 due to diffraction, no diffraction occurs in the plane-perpendicular direction, that is, in the Z-axis direction.
- the phase modulation layer 15 of the M-point oscillation light emitting device 1 is devised as follows to output part of +1st order light and -1st order light without outputting 0th order light.
- a diffraction vector V1 having a certain magnitude and direction is added to the in-plane wavenumber vectors K1 to K4.
- the magnitude of at least one of the in-plane wavevectors K1 to K4 is made smaller than 2 ⁇ / ⁇ .
- ⁇ is the wavelength of light output from the active layer 12 .
- the light line LL is a circular area with a radius of 2 ⁇ / ⁇ .
- the in-plane wavenumber vectors K1 to K4 indicated by dashed lines in FIG. 11 represent before addition of the diffraction vector V1.
- the in-plane wavenumber vectors K1 to K4 indicated by solid lines in FIG. 11 represent after addition of the diffraction vector V1.
- Light line LL corresponds to the total internal reflection condition.
- a wave vector having a magnitude within the light line LL has a component in the direction perpendicular to the plane, that is, in the Z-axis direction.
- the direction of the diffraction vector V1 is along the ⁇ -M1 axis or the ⁇ -M2 axis.
- the magnitude of diffraction vector V1 is in the range from 2 ⁇ /( ⁇ 2)a ⁇ 2 ⁇ / ⁇ to 2 ⁇ /( ⁇ 2)a+2 ⁇ / ⁇ , and in one example is 2 ⁇ /( ⁇ 2)a.
- Equations (8)-(11) below represent the in-plane wavevectors K1-K4 before the diffraction vector V1 is added.
- Spreads ⁇ kx and ⁇ ky of the in-plane wavevectors satisfy the following equations (12) and (13), respectively.
- the maximum x-axis spread ⁇ kx max and the maximum y-axis spread ⁇ ky max of the in-plane wave vector are defined by the angular spread of the designed optical image.
- a diffraction vector V1 is represented by the following formula (14).
- the in-plane wavenumber vectors K1 to K4 to which the diffraction vector V1 is added are given by the following equations (15) to (18).
- Equation (19) Considering that any one of the in-plane wavevectors K1 to K4 falls within the light line LL in the equations (15) to (18), the relationship of the following equation (19) holds. That is, by adding the diffraction vector V1 that satisfies Equation (19), any one of the in-plane wavenumber vectors K1 to K4 fits within the light line LL, and a part of the +1st order light and -1st order light is output.
- FIG. 12 is a diagram for schematically explaining the peripheral structure of the light line LL.
- the figure shows the boundary between the device and air in the Z direction.
- the magnitude of the wave vector of light in a vacuum is 2 ⁇ / ⁇ , but when light propagates through a device medium as shown in FIG. becomes.
- wavenumber conservation law in order for light to propagate through the boundary between the device and air, wavenumber components parallel to the boundary must be continuous.
- the length of the wave vector projected into the plane that is, the in-plane wave vector Kb is (2 ⁇ n/ ⁇ ) sin ⁇ . Since the refractive index n of a medium is generally greater than 1, the law of conservation of wavenumbers does not hold at an angle ⁇ at which the in-plane wavenumber vector Kb in the medium is greater than 2 ⁇ / ⁇ . At this time, the light is totally reflected and cannot be taken out to the air side.
- the magnitude of the wave vector corresponding to this total reflection condition is the magnitude of the light line LL, ie, 2 ⁇ / ⁇ .
- phase distribution ⁇ 1 (x, y) corresponding to the desired shape of emitted light
- ⁇ 2 (x, y) A method of superimposing the phase distribution ⁇ 2 (x, y) is conceivable.
- ⁇ 1 (x, y) corresponds to the phase of the complex amplitude when the desired shape of the output light is Fourier transformed as described above.
- ⁇ 2 (x, y) is the phase distribution for adding the diffraction vector V1 that satisfies Equation (19) above.
- FIG. 13 is a diagram conceptually showing an example of the phase distribution ⁇ 2 (x, y).
- the first phase value ⁇ A and the second phase value ⁇ B different from the first phase value ⁇ A are arranged in a checkered pattern.
- the phase value ⁇ A is 0 (rad) and the phase value ⁇ B is ⁇ (rad).
- the difference between the first phase value ⁇ A and the second phase value ⁇ B is ⁇ .
- Such an arrangement of phase values can suitably realize a diffraction vector V1 along the ⁇ -M1 axis or the ⁇ -M2 axis.
- V1 ( ⁇ /a, ⁇ /a), so that the diffraction vector V1 and any one of the in-plane wavevectors K1 to K4 shown in FIG. canceled out. Therefore, the axis of symmetry between the +1st order light and the ⁇ 1st order light coincides with the Z direction, that is, the direction perpendicular to the in-plane direction of the phase modulation layer 15 .
- the angular distribution ⁇ 2 (x, y) corresponding to the phase distribution ⁇ 2 (x, y) of the diffraction vector V is expressed by the inner product of the diffraction vector V (Vx, Vy) and the position vector r (x, y).
- the wavenumber spread based on the angular spread of emitted light is included in a circle with a radius ⁇ k centered at a certain point on the wavenumber space, it can be simply considered as follows.
- the magnitude of at least one of the in-plane wave vectors K1 to K4 in the four directions is made smaller than 2 ⁇ / ⁇ , ie, the light line LL.
- the magnitude of at least one of the in-plane wavevectors K1-K4 in the four directions is smaller than the value ⁇ (2 ⁇ / ⁇ ) ⁇ k ⁇ obtained by subtracting the wavenumber spread ⁇ k from 2 ⁇ / ⁇ .
- FIG. 14 is a diagram conceptually showing the above concept.
- the magnitude of at least one of the in-plane wavenumber vectors K1 to K4 is ⁇ (2 ⁇ / ⁇ ) ⁇ k ⁇ .
- the area LL2 is a circular area with a radius of ⁇ (2 ⁇ / ⁇ ) ⁇ k ⁇ .
- the in-plane wavenumber vectors K1 to K4 indicated by dashed lines represent before addition of the diffraction vector V1.
- FIG. 14 the in-plane wavenumber vectors K1 to K4 indicated by dashed lines represent before addition of the diffraction vector V1.
- the in-plane wavenumber vectors K1 to K4 indicated by solid lines represent after addition of the diffraction vector V1.
- the region LL2 corresponds to the total reflection condition considering the wave number spread ⁇ k.
- a wave vector having a magnitude within the region LL2 also propagates in the plane-perpendicular direction, that is, in the Z-axis direction.
- Equations (20)-(23) below represent the in-plane wavevectors K1-K4 before the diffraction vector V1 is added.
- the in-plane wavenumber vectors K1 to K4 after the addition of the diffraction vector V1 are given by the following formulas (24) to (27). .
- Equation (28) considering that any one of the in-plane wave vectors K1 to K4 falls within the region LL2, the relationship of the following equation (28) holds. That is, by adding the diffraction vector V1 that satisfies Equation (28), any one of the in-plane wavenumber vectors K1 to K4 excluding the wavenumber spread ⁇ k falls within the region LL2. Even in such a case, it is possible to output part of the +1st order light and -1st order light without outputting the 0th order light.
- FIG. 15 is a plan view showing another form of the phase modulation layer 15.
- FIG. FIG. 16 is a diagram showing the arrangement of the modified refractive index regions 15b in the phase modulation layer 15 shown in FIG.
- the centers of gravity G of the plurality of modified refractive index regions 15b of the phase modulation layer 15 may be arranged on the plurality of straight lines D, respectively.
- a straight line D is a straight line that passes through the lattice point O corresponding to each unit constituent region R and is inclined with respect to each side of the square lattice. That is, the straight line D is a straight line that is inclined with respect to both the X-axis and the Y-axis.
- One side of the square lattice, in other words, the inclination angle of the straight line D with respect to the X axis is ⁇ .
- the tilt angle ⁇ is uniform within the phase modulation layer 15 .
- the distance between the grid point O and the center of gravity G be r(x, y).
- x is the position of the x-th grid point on the X-axis
- y is the position of the y-th grid point on the Y-axis. If the distance r(x,y) is a positive value, the center of gravity G is located in the first quadrant or the second quadrant. If the distance r(x,y) is a negative value, the center of gravity G is located in the 3rd or 4th quadrant. When the distance r(x, y) is 0, the lattice point O and the center of gravity G coincide with each other.
- the inclination angle ⁇ is preferably 45°, 135°, 225° and 275°.
- the distance r (x, y) between the center of gravity G of each modified refractive index region and the lattice point O corresponding to each unit constituent region R is a modified refractive index according to the phase distribution ⁇ (x, y) according to the desired shape of emitted light. It is set individually for each rate area 15b.
- the distance r(x, y) between the center of gravity G of at least two modified refractive index regions 15b and the lattice point O is different from each other.
- such an arrangement form of the center of gravity G is referred to as a second arrangement form.
- the phase distribution ⁇ (x, y) and the distribution of the distance r(x, y) have specific values for each position determined by the values of x, y, but are not necessarily represented by specific functions.
- the distribution of the distance r(x, y) is determined by extracting the phase distribution ⁇ (x, y) from the complex amplitude distribution obtained by inverse Fourier transforming the desired emitted light shape.
- the distance r(x, y) is set to 0 when the phase ⁇ (x, y) at a certain coordinate (x, y) is ⁇ 0 . If the phase ⁇ (x,y) is ⁇ + ⁇ 0 , then set the distance r(x,y) to the maximum value R 0 . If the phase ⁇ (x, y) is - ⁇ + ⁇ 0 , set the distance r(x, y) to the minimum value -R 0 . Then, for the intermediate phase ⁇ ( x , y), the distance r( x , y ).
- the initial phase ⁇ 0 can be set arbitrarily.
- the maximum value R 0 of r(x, y) falls within the range of the following formula (29), for example.
- the distribution of the distance r(x, y) of the modified refractive index region 15b of the phase modulation layer 15 is determined to obtain the desired light emission shape with respect to the number and position of the condensing points. Obtainable.
- the phase modulation layer 15 is configured to satisfy the following conditions. That is, the corresponding modified refractive index region 15b is a unit configuration so that the distance r (x, y) from the lattice point O (x, y) to the center of gravity G of the corresponding modified refractive index region 15b satisfies the following relationship: It is placed in the region R(x,y).
- r(x,y) C ⁇ ( ⁇ (x,y) ⁇ 0 )
- C constant of proportionality, such as R 0 / ⁇ ⁇ 0 : Any constant, for example 0
- the light emission shape is subjected to an inverse Fourier transform, and the distribution of the distance r(x, y) corresponding to the phase ⁇ (x, y) of the complex amplitude is converted to a plurality of different refractive indices. It may be applied to region 15b.
- the phase ⁇ (x,y) and the distance r(x,y) may be proportional to each other.
- the lattice spacing a of the virtual square lattice and the emission wavelength ⁇ of the active layer 12 satisfy the conditions for M-point oscillation, as in the first arrangement form described above. Furthermore, when considering a reciprocal lattice space in the phase modulation layer 15, the magnitude of at least one of the four in-plane wavevectors K1 to K4 including the wavenumber spread due to the distribution of the distance r(x, y) is 2 ⁇ / ⁇ , which is smaller than the light line LL.
- the phase modulation layer 15 is devised as follows to prevent the 0th-order light from being output into the light line LL, and the +1st-order light and the +1st-order light Output a part of the ⁇ 1st order light. Specifically, as shown in FIG. 11, a diffraction vector V1 having a certain magnitude and direction is added to the in-plane wavenumber vectors K1 to K4. This makes the magnitude of at least one of the in-plane wavevectors K1 to K4 smaller than 2 ⁇ / ⁇ .
- At least one of the in-plane wavevectors K1 to K4 to which the diffraction vector V1 is added is contained within the light line LL, which is a circular area with a radius of 2 ⁇ / ⁇ .
- the light line LL which is a circular area with a radius of 2 ⁇ / ⁇ .
- the in-plane wavenumber vectors K1 to K4 in the four directions excluding the wavenumber spread ⁇ k that is, the in-plane wavenumber vectors in the four directions in the square lattice PCSEL with M-point oscillation are obtained by obtaining diffraction vectors V1 may be added.
- the magnitude of at least one of the four in-plane wavevectors K1 to K4 may be smaller than ⁇ (2 ⁇ / ⁇ ) ⁇ k ⁇ , which is obtained by subtracting the wavenumber spread ⁇ k from 2 ⁇ / ⁇ .
- any one of the in-plane wavenumber vectors K1 to K4 falls within the region LL2, and a part of the +1st order light and -1st order light is output. .
- phase modulation layer 15 for condensing and emitting light from the light emitting device 1 will be described in detail.
- phase modulation layer 15 for forming a single condensing point U by the light emitting device 1 itself will be described.
- the phase distribution ⁇ 1 (x, y) for obtaining the desired emitted light shape the phase distribution including the lens elements for condensing the emitted light, that is, the lens phase distribution ⁇ L (x, y) set.
- FIG. 17 is a diagram showing an example of the lens phase distribution ⁇ L (x, y).
- the magnitude of the phase is represented by the shade of color, and the darker the color, the closer to 0 (rad), and the lighter the color, the closer to 2 ⁇ (rad).
- This lens phase distribution ⁇ L (x, y) can act as a convex lens element for outgoing light.
- This lens phase distribution ⁇ L (x, y) is expressed by Equation (30). is the wavelength in the medium in the phase modulation layer 15, (x, y) is the in-plane lattice point position, and f is the focal length.
- the sign of the focal length f may be either + or -. When the sign of the focal length f is +, it becomes a concave lens, and when it is ⁇ , it becomes a convex lens.
- FIG. 18 is a partially enlarged view of the lens phase distribution ⁇ L (x, y).
- this lens phase distribution ⁇ L (x, y) is viewed locally, similar to FIG. are arranged in a checkered pattern.
- a lens phase distribution ⁇ L (x,y) allows the aforementioned diffraction vector V1 to be added to the in-plane wavevectors K1 to K4.
- the phase value of each portion of the phase modulation layer 15 is obtained as the sum of the average values of the first and second phase values included in each portion.
- 19 and 20 are diagrams showing the results of the experiment.
- the light-emitting device 1 of the present embodiment was prototyped, and a near-field image was taken while moving the objective lens in the Z direction.
- the emission wavelength ⁇ of the prototype light emitting device 1 was set to 940 nm
- the lattice spacing a was set to 202 nm
- the length r of the vector connecting the lattice point O and the center of gravity G was set to 0.08 a
- the focal length f was set to 0.32 mm.
- FIG. 19 shows a case where the lens phase distribution ⁇ L (x, y) is a convex lens.
- FIG. 20 shows a case where the lens phase distribution ⁇ L (x, y) is a concave lens.
- FIG. 21 shows the result of similarly taking a near-field image of a normal light-emitting device (LED) without the phase modulation layer 15. As shown in FIG. In FIGS. 19 to 21, the light intensity is represented by color gradation, and the lighter the color, the higher the light intensity.
- the emitted light converges at a position 0.3 mm from the light emitting surface.
- light can be emitted while being condensed.
- the emitted light converged even at a position of ⁇ 0.3 mm from the light emitting surface.
- the position ⁇ 0.3 mm from the light emitting surface is the opposite side of the light emitting device 1 from the light emitting surface.
- the reason is considered as follows. That is, as shown in FIG. 22, +1st order light La and ⁇ 1st order light Lb are emitted from the phase modulation layer 15 of the light emitting device 1 in mutually symmetrical directions.
- the +1st order light La converges at a condensing point U at a certain distance from the phase modulation layer 15 and at a certain point on the opposite side from the phase modulation layer 15 .
- -1st-order light Lb as a virtual image converges at the condensing point UD of the distance.
- +1st-order light La converges at a condensing point U 0.3 mm from the phase modulation layer 15, and -1st-order light as a virtual image at a condensing point UD -0.3 mm from the phase modulation layer 15.
- Lb is converging.
- the lens phase distribution ⁇ L (x, y) is a concave lens
- the ⁇ 1st-order light Lb converges at a condensing point U at a certain distance from the phase modulation layer 15 and reverses from the phase modulation layer 15 .
- +1st-order light La converges at a condensing point UD at a certain distance on the side.
- ⁇ 1st order light Lb converges at a condensing point U 0.3 mm from the phase modulation layer 15, and +1st order light La converges at a convergence point UD ⁇ 0.3 mm from the phase modulation layer 15. is doing.
- any one of the in-plane wavenumber vectors K1 to K4 becomes a zero vector, and the axis of symmetry between the +1st-order light and the ⁇ 1st-order light is the Z direction, that is, the direction perpendicular to the in-plane direction of the phase modulation layer 15. matches
- the length of the in-plane wavevectors K1-K4 are all made greater than zero by modifying the diffraction vector V1. That is, the in-plane wavenumber vectors K1 to K4 are assumed to be non-zero vectors. As a result, the axis of symmetry between the +1st order light and the ⁇ 1st order light is tilted from the Z direction. In other words, the center position of the light image output from the light emitting device 1 is separated from the axis extending in the Z direction through the center of the light emitting surface of the light emitting device 1 .
- the phase distribution ⁇ (x, y) including the lens phase distribution ⁇ L (x, y) is expressed as follows.
- the component of the phase distribution corresponding to the non-zero vector (dVx, dVy) converges the emitted light to one converging point U in the phase distribution ⁇ (x, y) together with the lens phase distribution ⁇ L (x, y).
- FIG. 23 is a diagram showing an example of the phase distribution ⁇ (x, y) including the lens phase distribution ⁇ L (x, y) and the component corresponding to the non-zero vector (dVx, dVy).
- the magnitude of the phase is represented by the shade of color, and the darker the color, the closer to 0 (rad), and the lighter the color, the closer to 2 ⁇ (rad).
- phase modulation layer 15 for forming a plurality of condensing points U by the single light emitting device 1 itself
- phase distribution ⁇ 1 (x, y) may consist only of a phase distribution obtained by synthesizing the hologram phase distribution ⁇ H (x, y) and the lens phase distribution ⁇ L (x, y). Note that the hologram phase distribution ⁇ H (x, y) corresponds to the first phase distribution in the present disclosure, and the lens phase distribution ⁇ L (x, y) corresponds to the second phase distribution in the present disclosure.
- the hologram phase distribution ⁇ H (x,y) forms the at least two points at positions away from an axis passing through the center of the light exit surface of the light emitting device 1 and extending in the Z direction.
- the hologram phase distribution ⁇ H (x, y) is a phase distribution in which the in-plane wavenumber vectors K1 to K4 are non-zero vectors, and is a hologram for emitting light toward two or more points different from each other.
- methods for synthesizing the hologram phase distribution ⁇ H (x, y) and the lens phase distribution ⁇ L (x, y) include, for example, the following methods.
- the synthesized phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) are calculated for each imaginary plane.
- n is the number of imaginary planes.
- the synthesized phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) are synthesized with each other.
- the synthesized phase distribution is included in the phase distribution ⁇ 1 (x, y) as an element for condensing the emitted light to at least two condensing points U.
- One method is to divide each of the synthetic phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) into a real part and an imaginary part, and perform phase synthesis on each of the real part and the imaginary part.
- This method is hereinafter referred to as the first method.
- each of the synthesized phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) is divided into a real part and an imaginary part (processes B1 and B2 in the figure).
- Another method is to use the average value of the composite phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) as the phase distribution ⁇ 1 (x, y).
- This method is hereinafter referred to as the second method.
- the phase distribution ⁇ 1 (x, y) at coordinates (x, y) is calculated as ( ⁇ s 1 + ⁇ s 2 + . . . + ⁇ s n )/n.
- Still another method is to randomly select phase values two-dimensionally from each of the combined phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) and superimpose the selected phase values.
- This method is hereinafter referred to as the third method.
- this third method at each coordinate (x, y), two or more The phase values of the composite phase distributions ⁇ s 1 (x, y) to ⁇ s n (x, y) of .
- FIG. 25 shows a random pattern 50B applied to the synthesized phase distribution ⁇ s 2 (x, y).
- These random patterns 50A and 50B have a plurality of regions 51 arranged two-dimensionally along the x-direction and the y-direction. These regions 51 are in one-to-one correspondence with each phase value of the phase distribution.
- a plurality of regions 51 are colored black and white.
- the white area is the area 52 where the phase value is selected
- the black area is the area 53 where the phase value is not selected.
- the region 52 will be referred to as a selected region
- the region 53 will be referred to as a non - selected region.
- the coordinates (x, y) is selected from the combined phase distribution ⁇ s 2 (x, y), the phase value of coordinates (x, y) corresponding to the selected region 52 of the random pattern 50B is selected.
- the selected areas 52 of the random pattern 50A and the selected areas 52 of the random pattern 50B are complementarily distributed. is always the non-selected region 53.
- the non-selected region 53 in the random pattern 50A is always the selected region 52 in the random pattern 50B, and the selected region 52 is two-dimensionally randomly distributed in the xy plane.
- the number of selected regions 52 in random pattern 50A may be equal to or slightly different from the number of selected regions 52 in random pattern 50B.
- the number of phase values obtained may be equal to or slightly different from the number of phase values selected from the composite phase distribution ⁇ s 2 (x,y).
- a value is assigned to each region from a random number of 0 to 1, the region where the value is 0 or more and less than 1/2 is defined as the selection region 52 of the random pattern 50A, and the region where the value is 1/2 or more and 1 or less , as the selected area 52 of the random pattern 50B.
- the Rand function of MATLAB registered trademark
- MATLAB registered trademark
- n may be 3 or more.
- the selected region 52 of the random pattern corresponding to the combined phase distribution ⁇ s 1 (x, y), the selected region 52 of the random pattern corresponding to the combined phase distribution ⁇ s 2 (x, y), and the combined phase Random pattern selection regions 52 corresponding to the distribution ⁇ s 3 (x, y) are distributed complementarily. That is, the selected region 52 in the random pattern corresponding to the synthesized phase distribution ⁇ s 1 ( x , y) is It is always the non-selected area 53 .
- the selected region 52 in the random pattern corresponding to the composite phase distribution ⁇ s 2 (x, y) is always non-uniform in each random pattern corresponding to the other composite phase distributions ⁇ s 1 (x, y) and ⁇ s 3 (x, y). This is the selection area 53 .
- the selected region 52 in the random pattern corresponding to the composite phase distribution ⁇ s 3 (x, y) is always non-uniform in each random pattern corresponding to the other composite phase distributions ⁇ s 1 (x, y) and ⁇ s 2 (x, y). This is the selection area 53 .
- An example of a method for creating such a random pattern will be given.
- a value is assigned to each region from a random number of 0 to 1, and the region where the value is 0 or more and less than 1/3 is defined as the random pattern selection region 52 corresponding to the synthetic phase distribution ⁇ s 1 (x, y). Then, a region of 1/3 or more and less than 2/3 is defined as a random pattern selection region 52 corresponding to the synthesized phase distribution ⁇ s 2 (x, y), and a region of 2/3 or more and 1 or less is defined as a synthetic There is a method of defining as a random pattern selected region 52 corresponding to the phase distribution ⁇ s 3 (x, y). Also when n is 4 or more, random patterns can be created by the same method as the above method.
- +1st-order light can be emitted toward at least two points according to the hologram phase distribution ⁇ H (x, y). Therefore, at least two focal points U can be formed using only the +1st order light.
- FIG. 26 is a diagram showing the position of the condensing point U.
- one condensing point U was separated by a predetermined distance in the +Y direction from an axis extending in the Z direction through the center of the light emitting surface of the light emitting device 1. formed in the same position.
- a distance z in the Z direction from the light exit surface to this condensing point U is 1 mm.
- another condensing point U is set in the ⁇ Y direction from the axis passing through the center of the light emitting surface of the light emitting device 1 and extending in the Z direction. formed at a distance.
- a distance z in the Z direction from the light exit surface to this condensing point U is 2 mm.
- the emission wavelength ⁇ , the lattice spacing a, and the length r of the vector connecting the lattice point O and the center of gravity G of the prototype light emitting device 1 were the same as in FIGS.
- FIGS. 27 to 29 show near-field images of the light-emitting device 1 fabricated in this experiment.
- FIG. 27 shows a near-field image of the light-emitting device 1 produced by the second method described above.
- FIG. 28 shows a near-field image of the light-emitting device 1 produced by the first method described above (see FIG. 24).
- FIG. 29 shows a near-field image of the light-emitting device 1 produced by the third method described above.
- the light intensity is represented by color gradation, and the lighter the color, the higher the light intensity.
- approximately square noise is confirmed near the center.
- the magnitude of this substantially square noise does not change significantly even if the defocus distance z is changed within the range shown in FIG. Therefore, it is considered to be a defocused image, which is a near-field image to which the condensing action of the lens phase does not reach.
- the spread of the defocused image shown in FIG. 27 is smaller than the spread of the defocused image of the light emitting element (LED) shown in FIG. This is due to laser oscillation in a relatively large area with respect to the wavelength.
- the substantially square noise is the light diffracted in the direction perpendicular to the plane by the action of the diffraction vector V1 from the in-plane resonating standing wave, that is, the light that has not been phase-modulated by the combined phase of the hologram phase and the lens phase. considered an ingredient. Therefore, it is more preferable to fabricate the light emitting device 1 by either the first method or the third method.
- FIG. 30 is a diagram showing the position of the condensing point U.
- FIG. 30 In this experiment, as shown in part (a) of FIG. 30, a large number of condensing points U were arranged along the X direction across an axis passing through the center of the light emitting surface of the light emitting device 1 and extending in the Z direction. arranged. The distance z in the Z direction from the light exit surface to these condensing points U is 1 mm.
- a large number of other converging points U are arranged in the Y direction across the axis passing through the center of the light emitting surface of the light emitting device 1 and extending in the Z direction. arranged along.
- the distance z in the Z direction from the light exit surface to these condensing points U is 2 mm.
- the emission wavelength ⁇ , the lattice spacing a, and the length r of the vector connecting the lattice point O and the center of gravity G of the prototype light emitting device 1 were the same as in FIGS.
- FIGS. 31 to 33 show near-field images of the light-emitting device 1 fabricated in this experiment.
- FIG. 31 shows a near-field image of the light-emitting device 1 produced by the second method described above.
- FIG. 32 shows a near-field image of the light-emitting device 1 produced by the first method (see FIG. 24) described above.
- FIG. 33 shows a near-field image of the light-emitting device 1 produced by the third method described above.
- the light intensity is represented by the shade of color, and the lighter the color, the higher the light intensity.
- approximately square noise is confirmed near the center. This substantially square noise is considered to have the same effect as the substantially square noise shown in FIG. 27 described above. Therefore, it is more preferable to fabricate the light emitting device 1 by either the first method or the third method.
- each modified refractive index region 15b is arranged away from the corresponding lattice point O of the virtual square lattice, and the predetermined phase distribution ⁇ (x, y) around the lattice point O has an individual rotation angle ⁇ according to .
- each modified refractive index region 15b is arranged on a straight line D that passes through the lattice point O of the virtual square lattice and is inclined with respect to the square lattice, and the center of gravity G of each modified refractive index region 15b and each A distance r from the lattice point O corresponding to the modified refractive index region 15b is individually set according to a predetermined phase distribution ⁇ (x, y).
- the S-iPM laser can generate an optical image of arbitrary shape.
- the lattice spacing a of the square lattice and the emission wavelength ⁇ of the active layer 12 satisfy the conditions for M-point oscillation.
- the signal light is, for example, one or both of +1st order light and -1st order light.
- the standing wave is phase-modulated by the phase distribution ⁇ (x, y) on the reciprocal lattice space of the phase modulation layer 15, and the wave number spread corresponding to the angular spread of the emitted light is changed to In-plane wavevectors K1 to K4 are formed in the four directions including.
- the magnitude of at least one of these in-plane wavevectors K1 to K4 is 2 ⁇ / ⁇ , ie smaller than the light line LL.
- such adjustment of the in-plane wavenumber vectors K1 to K4 is possible by devising the arrangement of the modified refractive index regions 15b.
- the in-plane wave vector When the magnitude of at least one in-plane wave vector is smaller than 2 ⁇ / ⁇ , the in-plane wave vector has a component in the thickness direction of the phase modulation layer 15, that is, in the Z direction, and at the interface with the air Does not produce total internal reflection. As a result, part of the signal light is output from the phase modulation layer 15 . However, when the conditions for the M-point oscillation are satisfied, the zero-order light is totally reflected at the interface with the air and is not output from the phase modulation layer 15 into the light line LL. That is, according to the light emitting device 1 of the present embodiment, the 0th order light contained in the output of the S-iPM laser can be removed from the light line LL, and only the signal light can be output.
- the phase distribution ⁇ (x, y) includes elements for condensing the emitted light Lout.
- the light-emitting device 1 can output light while concentrating it.
- the light-emitting device 1 suppresses the output of 0th-order light that does not contribute to condensing, so that only signal light that can contribute to condensing can be output.
- the number of optical components for collecting light can be reduced, and the size of the light source device can be reduced.
- the element for condensing the emitted light Lout included in the phase distribution ⁇ (x, y) may be an element for condensing the emitted light Lout to at least two condensing points U.
- the light-emitting device 1 by appropriately designing the light-collecting elements included in the phase distribution ⁇ (x, y), one light-emitting device 1 can emit light to at least two light-concentrating points U. It is also possible to collect the emitted light Lout. Therefore, at least two optical parts for condensing light can be eliminated, and the light source device can be further miniaturized.
- Elements for condensing the output light Lout included in the phase distribution ⁇ (x, y) are such that the magnitudes of the in-plane wave vectors K1 to K4 in the four directions are all greater than 0, that is, the in-plane wave vector K1 ⁇ K4 may be a non-zero vector.
- such an element can converge the emitted light Lout to a single converging point U.
- the phase distribution ⁇ (x, y) consists of a hologram phase distribution ⁇ H (x, y) for emitting the emitted light Lout toward at least two points, and a lens phase distribution ⁇
- a phase distribution obtained by synthesizing L (x, y) may be included as the element.
- such an element can converge the emitted light Lout to at least two converging points U.
- At least two condensing points U may be arranged in the direction intersecting the thickness direction, that is, the Z direction.
- the light emitting device 1 can be used for applications such as causing the light from at least two condensing points U to interfere with each other.
- the elements of the phase distribution ⁇ (x, y) are elements for condensing the emitted light Lout to at least four condensing points U.
- the light spots U may be three-dimensionally distributed.
- the light-emitting device 1 can be used for purposes such as creating a three-dimensional, in other words, three-dimensional optical image.
- FIG. 34 is a schematic diagram showing the configuration of the three-dimensional measurement system 101 according to the second embodiment.
- the three-dimensional measurement system 101 includes a light source device 102 , a plurality of imaging units 103 and a measurement unit 104 .
- the multiple imaging units 103 are, for example, a pair of imaging units 103 .
- the light source device 102 includes one or a plurality of light emitting devices 1 of the first embodiment.
- the measurement light 105 emitted from the light source device 102 irradiates a certain area on the surface of the object to be measured SA placed on the stage 106 .
- Stage 106 may be a scanning stage capable of scanning in two or three dimensions. If the irradiation range of the measurement light 105 is sufficiently wide with respect to the measurement target range of the object to be measured SA, the arrangement of the stage 106 may be omitted.
- FIG. 35 is a diagram schematically showing a light source device 102A as an example of the configuration of the light source device 102.
- this light source device 102A includes one light emitting device 1A and an optical system 110.
- the optical system 110 is optically coupled with the light exit surface of the light emitting device 1A.
- the optical axis of optical system 110 coincides with axis AX1.
- the axis AX1 passes through the center of the light emitting surface of the light emitting device 1A and extends along the Z direction (see FIG. 1).
- the optical system 110 is a lens having a light converging function, such as a convex lens.
- the light-emitting device 1A is the light-emitting device 1 of the first embodiment, and forms two condensing points U1 and U2 located between the light-emitting device 1 and the optical system 110.
- This element converges the emitted light Lout1 output from the light emitting device 1A to the condensing point U1, and at the same time converges the emitted light Lout2 output from the light emitting device 1A to the condensing point U2.
- the condensing points U1 and U2 are formed side by side in a direction that intersects, for example, perpendicularly to the axis AX1.
- the distance from the axis AX1 to the focal point U1 is equal to the distance from the axis AX1 to the focal point U2.
- the focal points U1 and U2 are formed at symmetrical positions with respect to the axis AX1.
- the emitted light Lout1 is an example of the first emitted light in the present disclosure.
- the emitted light Lout2 is an example of the second emitted light in the present disclosure.
- Condensing point U1 is an example of a first condensing point in the present disclosure.
- Condensing point U2 is an example of a second condensing point in the present disclosure.
- FIG. 36 is a diagram schematically showing a light source device 102B as another example of the configuration of the light source device 102. As shown in FIG. As shown in the figure, this light source device 102B includes two light emitting devices 1B and 1C and an optical system 110. As shown in FIG. The normals of the light exit surfaces of the light emitting devices 1B, 1C are parallel to each other and lie in a common plane. Light emitting device 1B is an example of the first light emitting device in the present disclosure. Light emitting device 1C is an example of a second light emitting device in the present disclosure.
- the optical system 110 is provided in common for the two light emitting devices 1B and 1C, and is optically coupled to the light exit surfaces of the light emitting devices 1B and 1C.
- the optical axis of optical system 110 coincides with axis AX2.
- An axis AX2 passes through the midpoint of the light emitting devices 1B and 1C and extends along the Z direction (see FIG. 1).
- the optical system 110 is a lens having a light converging function, such as a convex lens.
- the light emitting devices 1B and 1C are the light emitting device 1 of the first embodiment.
- the element for condensing the emitted light included in the phase distribution ⁇ (x, y) of the phase modulation layer 15 of the light emitting devices 1B and 1C has the single converging point configuration described in the first embodiment. have.
- the element of the light emitting device 1B converges the emitted light Lout1 output from the light emitting device 1B to a condensing point U1 located between the light emitting device 1B and the optical system 110.
- the element of the light emitting device 1C converges the emitted light Lout2 output from the light emitting device 1C to the condensing point U2 located between the light emitting device 1C and the optical system 110.
- the formation positions of the condensing points U1 and U2 are the same as in the example shown in FIG.
- the emitted light Lout1 that has passed through the condensing point U1 and the emitted light Lout2 that has passed through the condensing point U2 pass through the optical system 110.
- FIG. The optical system 110 forms an image of the emitted light beams Lout1 and Lout2 on the imaging plane 115 and causes the emitted light beams Lout1 and Lout2 to interfere with each other on the imaging plane 115 .
- the interference light thus generated is irradiated onto the surface of the object to be measured SA as measurement light 105 shown in FIG.
- each figure shows a single lens as the optical system 110, the optical system 110 may be configured by combining a plurality of lenses.
- FIG. 37 is a diagram showing an interference light image on the imaging plane 115, that is, an intensity change pattern of the measurement light 105.
- the intensity change pattern of the measurement light 105 is a stripe pattern W1 in which the light intensity periodically changes in a sinusoidal shape along a certain direction A.
- the imaging unit 103 is configured by a device that is sensitive to the measurement light 105 emitted from the light source device 102 .
- a CCD (Charge Coupled Device) camera, a CMOS (Complementary MOS) camera, or other two-dimensional image sensor can be used.
- the imaging unit 103 images the object to be measured SA irradiated with the measurement light 105 and outputs an output signal indicating the imaging result to the measuring unit 104 .
- the measurement unit 104 is configured by a computer system including, for example, a processor, memory, and the like.
- the measurement unit 104 executes various control functions using a processor. Examples of computer systems include personal computers, microcomputers, cloud servers, and smart devices such as smartphones and tablet terminals.
- the measurement unit 104 may be configured by a PLC (programmable logic controller), or may be configured by an integrated circuit such as an FPGA (Field-programmable gate array).
- the measurement unit 104 is communicably connected to the imaging unit 103 .
- the measurement unit 104 performs three-dimensional shape measurement of the object SA based on the signal input from the imaging unit 103 .
- the measurement unit 104 measures the three-dimensional shape of the object SA based on the phase shift method using the sinusoidal stripe pattern W1. That is, the period T of the sinusoidal wave is equally divided into N, and the measurement is performed using a plurality of sinusoidal stripe patterns W1 whose phases are shifted by T/N. N is an integer. In other words, the phases of the plurality of sinusoidal stripe patterns W1 are shifted by 2 ⁇ /N.
- Such a phase shift can be realized, for example, by gradually moving the positions of the focal points U1 and U2 in the direction intersecting the axis AX.
- the light intensities of the measurement light 105 having the four sinusoidal stripe patterns W1 are I0 to I3, respectively, and the coordinates of the pixels of the imaging unit 103 are (x, y).
- the light intensities I0 to I3 on the surface of the object to be measured SA are represented by the following formulas (32) to (35).
- Ia(x,y) is the grid pattern amplitude
- Ib(x,y) is the background intensity
- ⁇ (x,y) is the initial phase.
- the initial phase ⁇ can be obtained by the following equation (36).
- the measured phase is converted to the height of the object to be measured SA.
- the height of the object to be measured SA can be measured at intervals smaller than the pitch of the sinusoidal stripe pattern W1.
- interference fringes are generated by the two outgoing light beams Lout1 and Lout2 respectively emitted toward the condensing points U1 and U2. be done.
- This interference fringe is a light image in which the light intensity increases and decreases sinusoidally along a certain direction, that is, a stripe pattern W1.
- a stripe pattern W1 can be suitably used in the three-dimensional measurement system 101.
- the light emitting devices 1A to 1C included in the light source device 102A or 102B can be made significantly smaller than conventional light sources. Therefore, the light source device 102A or 102B can be arranged even in a very small space.
- the light source device 102A or 102B can be inserted into small spaces that were impossible in the past, such as inside the body such as the oral cavity or the body cavity, the inside of a tube, the gap between walls, or the gap between furniture, equipment, etc. and the floor. can be Therefore, diagnostic imaging and examination in these small spaces can be facilitated.
- the light source devices 102A and 102B may include an optical system 110 optically coupled to the light emitting devices 1A to 1C.
- the condensing points U1 and U2 are located between the light emitting devices 1A to 1C and the optical system 110, and the emitted lights Lout1 and Lout2 may interfere with each other after passing through the optical system 110.
- FIG. In this case, the size Ja of the area irradiated with the stripe pattern W1 depends on the focal length of the light emitting devices 1A to 1C, the optical axis position of the optical system 110, and the focal point of the optical system 110. determined primarily by distance.
- the irradiation surface of the stripe pattern W1 is the angle between the optical axis of the emitted light Lout1, Lout2 and the axis AX1 or AX2.
- the interval between stripes of the stripe pattern W1 that is, the period of intensity change, can be changed arbitrarily, so that an appropriate interval between stripes can be realized according to the size of the object to be measured SA.
- FIG. 38 is a schematic diagram showing the configuration of a light source device 102C according to a comparative example. Unlike the light source device 102B shown in FIG. 36, this light source device 102C does not include an element for collecting light in the phase distribution ⁇ (x, y) of the light emitting devices 1B and 1C, and emits light as a plane wave. Output LoutA and LoutB, respectively. In addition, light source device 102C does not include optical system 110 . Emitted light LoutA from the light emitting device 1B is emitted in a direction Aa inclined by an angle ⁇ a with respect to the axis AX2.
- Emitted light LoutB from the light emitting device 1C is emitted in a direction Ab inclined by an angle - ⁇ a with respect to the axis AX2.
- the emitted light beams LoutA and LoutB interfere with each other to form interference fringes on the imaging plane 115, that is, the stripe pattern W1 shown in FIG.
- the size Ja of the area irradiated with the stripe pattern W1 is mainly determined by the size of the light emitting surface of each of the light emitting devices 1B and 1C. Moreover, it is difficult to make the size Ja of the region irradiated with the stripe pattern W1 larger than the light emitting surface of each of the light emitting devices 1B and 1C. Therefore, the size of the object to be measured SA that can be measured is limited.
- FIG. 39 schematically shows how the angle ⁇ a is increased.
- the angle ⁇ a is increased, the irradiation surface of the stripe pattern W1, that is, the imaging surface 115 approaches the light emitting devices 1B and 1C. Therefore, in order to change the stripe interval of the stripe pattern W1, it is necessary to change the arrangement of the light-emitting devices 1B and 1C, and there is a problem that the control freedom of the stripe interval is low.
- the light source device 102B of the present embodiment it is sufficient to change the interval between the condensing points U1 and U2 and the focal length of the optical system 110 in order to change the stripe interval of the stripe pattern W1.
- 1C need not be changed. Therefore, the stripe interval of the stripe pattern W1 can be easily changed.
- the light source device 102 of the present embodiment converges and emits the emitted light Lout1 and Lout2 by devising the phase distribution ⁇ (x, y) of the S-iPM laser, and causes them to interfere with each other.
- Mutual interference between two lights is not limited to the S-iPM laser, but can also be realized by spatially modulating the phase of light using, for example, a phase modulation type spatial light modulator (SLM).
- SLM phase modulation type spatial light modulator
- the technical concept of the method using the SLM and the method of the present embodiment using the iPM laser are significantly different.
- the SLM originally outputs modulated light in a direction that intersects the light modulating surface.
- signal light such as +1st-order light and -1st-order light corresponds to the modulated light of the SLM.
- ⁇ -point oscillation S-iPM lasers have been studied.
- zero-order light is emitted in a direction perpendicular to the light emitting surface. Since the 0th-order light is not affected by the phase distribution ⁇ (x, y), it becomes unnecessary light, that is, noise when the light is emitted while being condensed as in this embodiment.
- the S-iPM laser when the S-iPM laser is oscillated at M points, it is possible to suppress the zero-order light from being emitted in the direction perpendicular to the light emitting surface. However, if the S-iPM laser is simply oscillated at M points, the signal light such as +1st order light and -1st order light is not emitted in the direction intersecting the light emission surface.
- the diffraction vector V1 is added to the in-plane wave vectors K1 to K4, and the magnitude of at least one of the in-plane wave vectors K1 to K4 is set to 2 ⁇ / ⁇ , that is, the light line LL. Make smaller. This enables signal light to be emitted in a direction intersecting with the light emitting surface. Such a device cannot be easily conceived from the method using the SLM.
- the formation of a two-dimensional hologram in the plane perpendicular to the light emission direction, that is, the Z direction, has been demonstrated.
- the light-emitting device 1 of this embodiment can also realize a three-dimensional hologram by differentiating the positions of a plurality of condensing points in the Z direction. Formation of 3D holograms using S-iPM lasers has not been demonstrated so far.
- FIG. 40 is a schematic diagram partially showing the configuration of a light source device 102D according to the first modified example.
- a light source device 102D further includes a mask 112 for a mode filter in addition to the configuration of the light source device 102A of the second embodiment shown in FIG.
- the mask 112 has two optical apertures 113 and 114 that allow the emitted light beams Lout1 and Lout2 to pass therethrough.
- the position of the optical aperture 113 in the direction along the axis AX1, that is, in the Z direction overlaps with the focal point U1.
- the position of the optical aperture 114 in the same direction overlaps with the focal point U2.
- the inner diameter of the optical aperture 113 is larger than the light diameter of the emitted light Lout1 at the condensing point U1, that is, the beam waist diameter.
- the inner diameter of the optical aperture 114 is larger than the light diameter of the emitted light Lout2 at the condensing point U2, that is, the beam waist diameter.
- the configuration of the light source device 102D other than the mask 112 is the same as that of the light source device 102A of the second embodiment.
- the light source device 102B of the second embodiment may also further include a mask 112 as in the present modification.
- FIG. 41 is a diagram for explaining the effect of providing the mask 112.
- FIG. 41 When the emitted lights Lout1 and Lout2 are emitted from the light emitting device 1A, the -1st order light and/or the ghost light LG due to the rear surface reflection is emitted from the light emitting device 1A while being diffused at the same time as the emitted lights Lout1 and Lout2.
- the emitted light Lout1 is emitted from the light emitting device 1B and the emitted light Lout2 is emitted from the light emitting device 1C
- the -1st order light and/or the ghost light LG due to the back surface reflection is emitted from the light emitting device at the same time as the emitted light Lout1 and Lout2.
- the ghost light LG is, for example, light having a diffraction order code different from that of the emitted lights Lout1 and Lout2, and is, for example, ⁇ 1st order light.
- the mask 112 is not provided as shown in part (a) of FIG. 41, the ghost light LG overlaps the emitted lights Lout1 and Lout2, causing the spatial modes of the emitted lights Lout1 and Lout2 to be disturbed.
- a mask 112 is provided as shown in part (b) of FIG. 41, only the emitted lights Lout1 and Lout2 pass through the optical apertures 113 and 114, respectively, and the ghost light LG is blocked by the mask 112.
- FIG. Therefore, the ghost light LG can be removed from the emitted lights Lout1 and Lout2.
- the mode cleaning of the emitted light beams Lout1 and Lout2 can be easily performed.
- FIG. 42 is a diagram showing an example of the lens phase distribution ⁇ L (x, y) for condensing light only in one direction.
- the magnitude of the phase is represented by the shade of color, and the darker the color, the closer to 0 (rad), and the lighter the color, the closer to 2 ⁇ (rad).
- the X direction is the first direction in this embodiment, and the Y direction is the second direction in this embodiment.
- This lens phase distribution ⁇ L (x, y) can act as a one-dimensional concave lens element only in the Y direction with respect to emitted light.
- a lens phase distribution ⁇ L (x, y) as a one-dimensional lens element is represented by Equation (37). is the wavelength in the medium in the phase modulation layer 15, (x, y) is the in-plane lattice point position, and f is the focal length.
- the lens phase distribution ⁇ L (x, y) becomes a one-dimensional concave lens element, and the ⁇ 1st order light is condensed in the region where z>0.
- the lens phase distribution ⁇ L (x, y) becomes a one-dimensional convex lens element, and primary light is condensed in the region of z>0.
- a focal length f is, for example, 100 ⁇ m.
- FIG. 43 is a diagram conceptually showing the operation of forming a striped optical image.
- Part (a) of FIG. 43 schematically shows an example of a light image formed on one imaginary plane only by the hologram phase distribution ⁇ H (x, y).
- This optical image includes a plurality of bright spots E1 arranged in a line and at equal intervals on the X axis.
- Part (b) of FIG. 43 shows the hologram phase distribution ⁇ H (x, y) forming the optical image shown in part (a) of FIG. ) is schematically shown.
- a plurality of bright spots E1 formed by the hologram phase distribution ⁇ H (x, y) are extended in the Y direction by the lens phase distribution ⁇ L (x, y), as shown in part (b) of FIG. resulting in a plurality of bright lines L1.
- This is the result of each luminescent spot E1 once condensed in the Y direction and then expanded in the same direction.
- a one-dimensional lens that focuses light in a direction perpendicular to the alignment direction of the hologram phase distribution ⁇ H (x, y) forming a plurality of bright spots E1 arranged in a row on the X axis at regular intervals.
- a striped optical image can be obtained by superimposing the lens phase distribution ⁇ L (x, y) as an element.
- a striped optical image can be suitably used, for example, in the three-dimensional measurement system of the second embodiment.
- the inventor made a prototype of such a light-emitting device.
- FIG. 44 is a far-field image of a striped light image emitted from the prototype light-emitting device.
- FIG. 45 shows a far-field image when a striped optical image is formed only by the hologram phase distribution ⁇ H (x, y) without using the lens phase distribution ⁇ L (x, y). .
- a clear striped optical image contributes to improvement of measurement accuracy in a three-dimensional measurement system.
- light can be focused to a very short focal length of, for example, 100 ⁇ m compared to the case where a lens component such as a cylindrical lens is provided separately. Therefore, the striped pattern can be extended longer.
- FIG. 46 is a diagram conceptually showing an operation for forming a striped optical image different from the above.
- the aspect shown in FIG. 46 differs from the aspect shown in FIG. 43 in the shape of the optical image formed by the hologram phase distribution ⁇ H (x, y). That is, the optical image shown in part (a) of FIG. 46 includes a plurality of groups of bright spots EA1 arranged in a line on the X-axis at regular intervals.
- Each bright spot group EA1 includes four bright spots E1, E2, E3, and E4.
- the light intensities of the bright spots E2 and E3 are smaller than the light intensity of the bright spot E1 and equal to each other.
- the light intensity of the bright spot E4 is smaller than the light intensity of the bright spots E2 and E3.
- the light intensity of each bright spot is represented by the shade of color. The darker the color, the higher the light intensity, and the lighter the color, the lower the light intensity.
- the bright points E2 and E3 are arranged on both sides of the bright point E1 in the X direction.
- the bright spot E4 is arranged in the X direction between the bright spot E2 of the bright spot group EA1 to which the bright spot E4 belongs and the bright spot E3 of the bright spot group EA1 adjacent to the bright spot group EA1.
- the bright point E4 is arranged in the X direction between the bright point E3 of the bright point group EA1 to which the bright point E4 belongs and the bright point E2 of the bright point group EA1 adjacent to the bright point group EA1. good too.
- the bright points E1 to E4 are shifted in the Y direction, but some or all of them may be aligned in the Y direction.
- Part (b) of FIG. 46 shows the hologram phase distribution ⁇ H (x, y) forming the optical image shown in part (a) of FIG. ) is schematically shown.
- a plurality of bright spot groups EA1 formed by the hologram phase distribution ⁇ H (x, y) are extended in the Y direction by the lens phase distribution ⁇ L (x, y), as shown in part (b) of FIG. They are stretched to form a plurality of bright line groups LA1.
- each bright spot group EA1 is once condensed in the Y direction and then expanded in the same direction.
- a substantially sinusoidal intensity distribution is obtained in the X direction due to the difference in the light intensity of each bright line included in the bright line group LA1.
- the striped optical image thus obtained can also be suitably used in the three-dimensional measurement system of the second embodiment.
- FIG. 47 shows an aspect similar to the aspect shown in FIG.
- the aspect shown in FIG. 47 differs from the aspect shown in FIG. 46 in the shape of the optical image formed by the hologram phase distribution ⁇ H (x, y). That is, the optical image shown in part (a) of FIG. 47 includes a plurality of groups of bright spots EA2 arranged in a line on the X-axis at regular intervals.
- the multiple bright spot groups EA2 are arranged apart from each other in the X direction.
- Each bright spot group EA2 includes five bright spots E1, E2, E3, E4, and E5.
- the light intensities of the bright spots E2 and E3 are smaller than the light intensity of the bright spot E1 and equal to each other.
- the light intensities of the bright points E4 and E5 are smaller than the light intensities of the bright points E2 and E3 and equal to each other.
- the bright points E2 and E3 are arranged on both sides of the bright point E1 in the X direction.
- the bright points E4 and E5 are arranged on both sides of the bright points E1 to E3 in the X direction.
- the positions of the bright spots E1 to E5 in the Y direction match each other, but some or all of them may be shifted in the Y direction.
- Part (a) of FIG. 47 shows, as an example, a graph of the relative values of the light intensities of the bright points E1 to E5. In this example, when the light intensity of the bright point E1 is 1.0, the light intensity of the bright points E2 and E3 is 0.50, and the light intensity of the bright points E4 and E5 is 0.25.
- Part (b) of FIG. 47 shows the hologram phase distribution ⁇ H (x, y) forming the optical image shown in part (a) of FIG. ) is schematically shown.
- a plurality of bright spot groups EA2 formed by the hologram phase distribution ⁇ H (x, y) are extended in the Y direction by the lens phase distribution ⁇ L (x, y), as shown in part (b) of FIG. They are stretched to form a plurality of bright line groups LA2. This is the result that each bright spot group EA2 is once condensed in the Y direction and then expanded in the same direction.
- FIG. 48 is a far-field image of a striped light image emitted from the prototype light-emitting device. Compared with FIG. 45, it can be seen that even in the far-field image shown in FIG. 48, the noise included in the optical image, that is, uneven brightness is significantly reduced, and a clear striped pattern is obtained.
- FIG. 49 shows another aspect similar to the aspect shown in FIG.
- the aspect shown in FIG. 49 differs from the aspect shown in FIG. 46 in the shape of the optical image formed by the hologram phase distribution ⁇ H (x, y). That is, the optical image shown in part (a) of FIG. 49 includes a plurality of groups of bright spots EA3 arranged in a line on the X-axis at regular intervals.
- the multiple bright spot groups EA3 are arranged apart from each other in the X direction.
- Each bright spot group EA3 includes five bright spots E6, E7, E8, E9, and E10.
- the light intensities of the bright points E6 to E10 are equal to each other, but the light intensities of the bright points E7 and E9 are smaller than the light intensity of the bright point E8 as shown in part (a) of FIG. , the light intensity of the bright spots E6 and E10 may be smaller than the light intensity of the bright spots E7 and E9.
- the bright points E6 to E10 are arranged in this order in the X direction, and when projected onto the X axis, the bright points E6 to E10 are continuous without gaps.
- the bright points E6 to E10 are shifted in the Y direction, but some or all of them may be aligned in the Y direction.
- Part (b) of FIG. 49 shows the hologram phase distribution ⁇ H (x, y) forming the optical image shown in part (a) of FIG. ) is schematically shown.
- a plurality of bright spot groups EA3 formed by the hologram phase distribution ⁇ H (x, y) are extended in the Y direction by the lens phase distribution ⁇ L (x, y), as shown in part (b) of FIG. They are stretched to form a plurality of bright line groups LA3. This is the result that each bright spot group EA3 is once condensed in the Y direction and then expanded in the same direction.
- the bright lines L6 to L10 are also adjacent to each other in the X direction.
- FIG. 50 is a far-field image of a striped light image emitted from the prototype light-emitting device. As compared with FIG. 45, the far-field image shown in FIG. 50 also shows that the noise included in the optical image, that is, the luminance unevenness is significantly reduced, and the striped pattern is made clearer.
- FIG. 51 is a diagram showing an example of such a lens phase distribution ⁇ L (x, y).
- the magnitude of the phase is represented by the shade of color, and the darker the color, the closer to 0 (rad), and the lighter the color, the closer to 2 ⁇ (rad).
- This lens phase distribution ⁇ L (x,y) can act as an asymmetric concave lens element for the emitted light.
- a lens phase distribution ⁇ L (x, y) as an asymmetric lens element is represented by Equation (38).
- ⁇ is the wavelength in the medium in the phase modulation layer 15
- (x, y) is the in-plane lattice point position
- fx is the focal length in the X direction
- fy is the focal length in the Y direction. is.
- the lens phase distribution ⁇ L (x, y) becomes an asymmetric concave lens element, and the primary light is focused in the region of z>0.
- the lens phase distribution ⁇ L (x, y) becomes an asymmetrical convex lens element, and the ⁇ 1st order light is condensed in the region of z>0.
- the focal length fx in the X direction is, for example, 10 mm.
- the focal length fy in the Y direction is, for example, 100 ⁇ m.
- FIG. 52 is a diagram conceptually showing the operation of forming a striped optical image.
- Part (a) of FIG. 52 is a diagram schematically showing an example of an optical image formed only by the hologram phase distribution ⁇ H (x, y). show.
- Part (b) of FIG. 52 shows the hologram phase distribution ⁇ H (x, y) forming the optical image shown in part (a) of FIG. ) is schematically shown.
- the plurality of bright lines L1 are extended in the Y direction by the lens phase distribution ⁇ L (x, y) as shown in part (b) of FIG. 52 .
- the plurality of bright lines L1 are also slightly stretched in the X direction by the lens phase distribution ⁇ L (x, y).
- a striped optical image can be obtained.
- Such a striped optical image can also be suitably used, for example, in the three-dimensional measurement system of the second embodiment.
- FIG. 53 is a far-field image of a striped light image emitted from the prototype light-emitting device.
- the far field of the prototype light-emitting device when using the one-dimensional lens phase distribution ⁇ L (x,y) shown in FIG. 42 instead of the asymmetric lens phase distribution ⁇ L (x,y)
- the image is shown in FIG. Comparing FIG. 53 and FIG. 44, according to the asymmetric lens phase distribution ⁇ L (x, y) according to this modification, the fringe width can be adjusted widely, which is required for a three-dimensional measurement system. It can be used for suitable width adjustment.
- the light-emitting device and light source device are not limited to the above-described embodiments, and various modifications are possible.
- laser elements made of GaAs-based, InP-based, and nitride-based (especially GaN-based) compound semiconductors are exemplified.
- the present disclosure can be applied to laser elements made of various semiconductor materials other than these.
- the active layer provided on the semiconductor substrate common to the phase modulation layer is used as the light emitting portion has been described.
- the light emitting section may be provided separately from the semiconductor substrate. As long as the light-emitting section is optically coupled to the phase modulation layer and supplies light to the phase modulation layer, even with such a configuration, the same effects as those of the above embodiments can be favorably achieved.
- the embodiments can be used as a light emitting device that can reduce the size of a light source device that collects and outputs light, and a light source device that includes the light emitting device.
- SYMBOLS 1, 1A-1C Light emitting device, 10... Semiconductor substrate, 10a... Main surface, 10b... Back surface, 11... Clad layer, 12... Active layer, 13... Clad layer, 14... Contact layer, 15... Phase modulation layer, 15a Basic area 15b Modified refractive index area 16, 17 Electrode 17a Opening 18 Protective film 19 Antireflection film 50A, 50B Random pattern 51 Area 52 Selected area 53 Non-selected area 100 S-iPM laser 101 three-dimensional measurement system 102, 102A to 102D light source device 103 imaging unit 104 measurement unit 105 measurement light 106 stage 110 optical system , 112... mask, 113, 114... optical aperture, 115... imaging plane, A...
- Aa Ab... emission direction, AX, AX1, AX2... axis line
- B1 basic reciprocal lattice vector, D... straight line, E1 ⁇ E10... Bright point, EA1 to EA3... Bright point group, FR... Image area, G... Centroid, K1 to K4, Ka, Kb... In-plane wavenumber vector, L1, L6 to L10... Bright line, LA1 to LA3... Bright line group, La... first-order light, Lb...-first-order light, LG... ghost light, LL... light line, LL2... area, LM... light image, Lout, Lout1, Lout2, LoutA, LoutB... emitted light, O... grid point, PM... Projection plane, R...
- Unit constituent area RIN... Inner area, ROUT... Outer area, SA... Object to be measured, U, U1, U2, UD... Condensing point, V1... Diffraction vector, W1... Stripe pattern, ⁇ a . . . angle, .theta.p .. irradiation angle.
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Abstract
Description
図1は、本開示の一実施形態に係る発光デバイス1の構成を示す一部切欠き斜視図である。図2は、発光デバイス1の積層構造を示す模式図である。図1及び図2では、発光デバイス1の中心において発光デバイス1の厚さ方向に延びる軸をZ軸とするXYZ直交座標系を定義している。
λ:発光デバイス1の発振波長
α(x,y)=C×φ(x,y)+B
C:比例定数であって例えば180°/π
B:任意の定数であって例えば0
θ2(x,y)=V・r=Vx・x+Vy・y
そのため、V=V1の場合、位置ベクトルをr(xa、ya)とすると位相値は0(rad)及びπ(rad)となる。x,yはともに整数である。一方、前述のように、回折ベクトルV1は、面内波数ベクトルK1~K4のうち少なくとも1つがライトラインLLに入る範囲内であれば、(±π/a、±π/a)からシフトしていてもよい。
r(x,y)=C×(φ(x,y)-φ0)
C:比例定数で例えばR0/π
φ0:任意の定数であって例えば0
所望の光出射形状を得たい場合、当該光出射形状を逆フーリエ変換して、その複素振幅の位相φ(x,y)に応じた距離r(x,y)の分布を複数の異屈折率領域15bに与えるとよい。位相φ(x,y)と距離r(x,y)とは、互いに比例してもよい。
まず、発光デバイス1自身により単一の集光点Uを形成するための位相変調層15の設計について説明する。この場合、所望の出射光形状を得る為の位相分布φ1(x,y)として、出射光を集光するためのレンズ要素を含む位相分布、すなわちレンズ位相分布φL(x,y)を設定する。図17は、レンズ位相分布φL(x,y)の例を示す図である。同図において、位相の大きさは色の濃淡によって表現されており、色が濃いほど0(rad)に近く、色が淡いほど2π(rad)に近い。この例では、位相変調層15の中心から離れるほど位相が小さくなっている。このレンズ位相分布φL(x,y)は、出射光に対して凸レンズ要素として作用することができる。このレンズ位相分布φL(x,y)は、数式(30)により表される。但し、λは位相変調層15における媒質中の波長であり、(x,y)は面内の格子点位置であり、fは焦点距離である。焦点距離fの符号は+及び-のいずれであってもよい。焦点距離fの符号が+である場合に凹レンズとなり、-である場合に凸レンズとなる。
次に、単一の発光デバイス1自身により単一の集光点Uを形成するための位相変調層15の設計の他の一つについて説明する。上述したように、図13に示した市松模様の位相分布φ2(x,y)によれば、回折ベクトルV1がV1=(±π/a,±π/a)となるので、回折ベクトルV1と、図10に示された面内波数ベクトルK1~K4のいずれか一つとが、丁度相殺される。したがって、面内波数ベクトルK1~K4のいずれか一つが零ベクトルとなり、+1次光と-1次光との対称軸が、Z方向、すなわち位相変調層15の面内方向に対して垂直な方向に一致する。
続いて、単一の発光デバイス1自身により複数の集光点Uを形成するための位相変調層15の設計の一つについて説明する。この設計では、出射光Loutを少なくとも2つの点に向けて出射するためのホログラム位相分布φH(x,y)と、出射光Loutを集光するためのレンズ位相分布φL(x,y)とを合成する。そして、合成して得られた位相分布を、出射光を少なくとも2つの集光点Uに集光するための要素として位相分布φ1(x,y)に含める。その後、この位相分布φ1(x,y)と、回折ベクトルV1のための位相分布φ2(x,y)との和を算出して最終的な位相分布φ(x,y)とする。位相分布φ1(x,y)は、ホログラム位相分布φH(x,y)とレンズ位相分布φL(x,y)とを合成して得られた位相分布のみから成ってもよい。なお、ホログラム位相分布φH(x,y)は本開示における第1の位相分布に対応し、レンズ位相分布φL(x,y)は本開示における第2の位相分布に対応する。
exp(j・φs1)=cos(φs1)+j・sin(φs1)
exp(j・φs2)=cos(φs2)+j・sin(φs2)
・
・
・
exp(j・φsn)=cos(φsn)+j・sin(φsn)
次に、合成位相分布φs1(x,y)~φsn(x,y)の実部同士、及び虚部同士を、下記のようにそれぞれ加算する(図中の処理B3,B4)。
実部Re=cos(φs1)+cos(φs2)+…+cos(φsn)
虚部Im=sin(φs1)+sin(φs2)+…+sin(φsn)
そして、これらの実部Re及び虚部Imを、下記のように極形式にて記述する(図中の処理B5)。
Re+j・Im=A・exp(j・φ1)
但し、Aは振幅であり、φ1は偏角である。
以上の計算により、各座標(x,y)における合成位相φ1、すなわち少なくとも2つの集光点Uに集光するための位相分布φ1(x,y)が得られる(図中の処理B6)。
図34は、第2実施形態に係る三次元計測システム101の構成を示す模式図である。同図に示すように、三次元計測システム101は、光源装置102と、複数の撮像部103と、計測部104とを含んで構成されている。複数の撮像部103は、例えば一対の撮像部103である。光源装置102は、第1実施形態の発光デバイス1を一個又は複数個含んで構成されている。光源装置102から出射される計測光105は、ステージ106上に載置された被計測物SAの表面の一定の領域に照射される。ステージ106は、2次元方向又は3次元方向に走査可能な走査ステージであってもよい。計測光105の照射範囲が被計測物SAの測定対象範囲に対して十分に広い場合、ステージ106の配置を省略してもよい。
図40は、第1変形例に係る光源装置102Dの構成を部分的に示す模式図である。光源装置102Dは、図35に示される第2実施形態の光源装置102Aの構成に加えて、モードフィルタのためのマスク112を更に備える。マスク112は、出射光Lout1,Lout2をそれぞれ通過させる2つの光学開口113,114を有する。軸線AX1に沿った方向すなわちZ方向における光学開口113の位置は、集光点U1と重なる。同方向における光学開口114の位置は、集光点U2と重なる。光学開口113の内径は、集光点U1における出射光Lout1の光径すなわちビームウエスト径よりも大きい。光学開口114の内径は、集光点U2における出射光Lout2の光径すなわちビームウエスト径よりも大きい。マスク112を除く他の光源装置102Dの構成は、第2実施形態の光源装置102Aと同じである。第2実施形態の光源装置102Bも本変形例と同様に、マスク112を更に備えてもよい。
続いて、第3実施形態について説明する。前述した各実施形態では、光を点状に集光する場合について説明した。本実施形態では、光を一方向においてのみ集光する場合について説明する。
ここで、第3実施形態の変形例として、Y方向だけでなくX方向にも僅かに集光作用を持たせることを考える。すなわち、X方向の焦点距離がY方向の焦点距離よりも長いレンズ位相分布φL(x,y)を設定する。図51は、そのようなレンズ位相分布φL(x,y)の例を示す図である。同図において、位相の大きさは色の濃淡によって表現されており、色が濃いほど0(rad)に近く、色が淡いほど2π(rad)に近い。このレンズ位相分布φL(x,y)は、出射光に対して非対称の凹レンズ要素として作用することができる。非対称のレンズ要素としてのレンズ位相分布φL(x,y)は、数式(38)により表される。但し、λは位相変調層15における媒質中の波長であり、(x,y)は面内の格子点位置であり、fxはX方向の焦点距離であり、fyはY方向の焦点距離である。右辺の符号が正である場合に、レンズ位相分布φL(x,y)は非対称の凹レンズ要素となり、1次光がz>0の領域に集光される。右辺の符号が負である場合に、レンズ位相分布φL(x,y)は非対称の凸レンズ要素となり、-1次光がz>0の領域に集光される。X方向の焦点距離fxは例えば10mmである。Y方向の焦点距離fyは例えば100μmである。
Claims (13)
- 発光部と、
前記発光部と光学的に結合され、基本領域と複数の異屈折率領域とを含み、前記複数の異屈折率領域が前記基本領域とは異なる屈折率を有し厚さ方向に垂直な面内において二次元状に分布する位相変調層と、
を備え、
各異屈折率領域の重心が第1の配置形態又は第2の配置形態を有し、
前記第1の配置形態では、各異屈折率領域の重心が、前記面内において設定された仮想的な正方格子の対応する格子点から離れて配置され、前記格子点周りに所定の位相分布に応じた個別の回転角度を有し、少なくとも2つの前記異屈折率領域の重心の前記回転角度が互いに異なり、
前記第2の配置形態では、各異屈折率領域の重心が、前記正方格子の格子点を通り前記正方格子に対して傾斜する直線上に配置され、前記複数の異屈折率領域にそれぞれ対応する複数の前記直線の前記正方格子に対する傾斜角が前記位相変調層内で均一であり、各異屈折率領域の重心と、各異屈折率領域に対応する格子点との距離が、前記所定の位相分布に応じて個別に設定され、少なくとも2つの前記異屈折率領域の重心の格子点との距離が互いに異なり、
前記正方格子の格子間隔と前記発光部の発光波長λとがM点発振の条件を満たし、
当該発光デバイスからの出射光の角度広がりに対応した波数拡がりをそれぞれ含む4方向の面内波数ベクトルが前記位相変調層の逆格子空間上において形成され、少なくとも1つの前記面内波数ベクトルの大きさが2π/λよりも小さく、
前記所定の位相分布は、前記出射光を少なくとも一方向において集光するための要素を含む、発光デバイス。 - 前記所定の位相分布の前記要素は、前記出射光を少なくとも2つの集光点に集光するための要素である、請求項1に記載の発光デバイス。
- 前記所定の位相分布は、前記出射光を少なくとも2つの点に向けて出射するための第1の位相分布と、前記出射光を集光するための第2の位相分布とを合成して得られる位相分布を前記要素として含む、請求項2に記載の発光デバイス。
- 前記少なくとも2つの集光点は、前記厚さ方向と交差する方向に並ぶ、請求項2又は3に記載の発光デバイス。
- 前記所定の位相分布の前記要素は、前記出射光を少なくとも4つの集光点に集光するための要素であり、
前記少なくとも4つの集光点は3次元的に分布する、請求項2又は3に記載の発光デバイス。 - 前記所定の位相分布は、第1方向に並ぶ複数の輝点を形成するホログラム位相分布と、前記第1方向と交差する第2方向においてのみ集光作用を有するレンズ位相分布とを重畳してなる、請求項1に記載の発光デバイス。
- 前記所定の位相分布は、第1方向に並ぶ複数の輝点群を形成するホログラム位相分布と、前記第1方向と交差する第2方向においてのみ集光作用を有するレンズ位相分布とを重畳してなり、
各輝点群は複数の輝点を含み、前記複数の輝点のうち少なくとも2つの輝点の光強度が互いに異なる、請求項1に記載の発光デバイス。 - 前記各輝点群は、前記第1方向における位置が互いに異なる第1の輝点、第2の輝点、及び第3の輝点を含み、
前記第2の輝点及び前記第3の輝点は前記第1の輝点を挟む位置に配置され、
前記第2の輝点及び前記第3の輝点の光強度は前記第1の輝点の光強度よりも小さい、請求項7に記載の発光デバイス。 - 前記所定の位相分布は、第1方向に並ぶ複数の輝点を形成するホログラム位相分布と、前記第1方向及び前記第1方向と交差する第2方向において集光作用を有し、前記第1方向における焦点距離が前記第2方向における焦点距離よりも長いレンズ位相分布とを重畳してなる、請求項1に記載の発光デバイス。
- 請求項1に記載の発光デバイスである第1及び第2の発光デバイスを備え、
前記第1の発光デバイスの前記所定の位相分布の前記要素は、前記第1の発光デバイスからの第1の出射光を第1の集光点に向けて集光し、
前記第2の発光デバイスの前記所定の位相分布の前記要素は、前記第2の発光デバイスからの第2の出射光を前記第1の集光点と並ぶ第2の集光点に向けて集光し、
前記第1の出射光と前記第2の出射光とを相互に干渉させて干渉縞を生成する、光源装置。 - 前記第1及び第2の発光デバイスと光学的に結合された光学系を更に備え、
前記第1の集光点は、前記第1の発光デバイスと前記光学系との間に位置し、
前記第2の集光点は、前記第2の発光デバイスと前記光学系との間に位置し、
前記第1の出射光と前記第2の出射光とは、前記光学系を通過した後に相互に干渉する、請求項10に記載の光源装置。 - 請求項2~4のいずれか1項に記載の発光デバイスを備え、
前記発光デバイスの前記所定の位相分布の前記要素は、前記発光デバイスからの第1の出射光を第1の集光点に向けて集光し、前記発光デバイスからの第2の出射光を第2の集光点に向けて集光し、
前記第1の出射光と前記第2の出射光とを相互に干渉させて干渉縞を生成する、光源装置。 - 前記発光デバイスと光学的に結合された光学系を更に備え、
前記第1及び第2の集光点は、前記発光デバイスと前記光学系との間に位置し、
前記第1の出射光と前記第2の出射光とは、前記光学系を通過した後に相互に干渉する、請求項12に記載の光源装置。
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