Optical module

Abstract

This optical module is provided with: a laser diode that emits laser light; a scanning unit that has a mirror that reflects the laser light, and that outputs the laser light to the outside by swinging the mirror; a protective container having a transmission window through which the laser light passes, the protective container surrounding the laser diode and the scanning unit; a control unit that performs control so that the laser light becomes a pulse wave; and an electronic temperature adjusting module for adjusting the temperature of the laser diode and the scanning part.

Description

Technical Field

[0001] The present disclosure relates to an optical module. This application claims priority based on Japanese Application No. 2022-133150 filed on August 24, 2022 and Japanese Application No. 2022-177940 filed on November 7, 2022, and all the contents described in the above Japanese Applications are hereby incorporated by reference. Background Art

[0002] A focusing optical system has been disclosed, in which an emitted laser is reflected by an object, and the reflected return light is reflected by a reflection surface around a perforated reflection mirror via a scanning mirror and received by a light receiving element (for example, see Patent Document 1). In addition, an optical module that combines lasers and outputs them has been disclosed (for example, see Patent Document 2).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2004-170965

[0006] Patent Document 2: International Publication No. 2019 / 211943 Summary of the invention

[0007] The optical module disclosed in the present invention comprises: a laser diode that emits laser light; a scanning unit that has a reflector that reflects the laser light and swings the reflector to output the laser light to the outside; a protective container that has a transmission window for the laser light to pass through and surrounds the laser diode and the scanning unit; a control unit that controls so that the laser light becomes a pulse wave; and an electronic temperature adjustment module that adjusts the temperature of the laser diode and the scanning unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a perspective view of the appearance of the optical module according to the first embodiment.

[0009] Figure 2 It is shown Figure 1 A schematic top view of the structure of the optical module is shown.

[0010] Figure 3 It is shown in Figure 1 A schematic top view of the optical module is shown with the cover removed.

[0011] Figure 4 yes Figure 1 A simplified side view of the optical module is shown.

[0012] Figure 5 It is shown Figure 1 The optical module shown is a perspective view of the appearance of the optical module with the cover removed.

[0013] Figure 6 It is a schematic top view of the mirror driving mechanism included in the optical module.

[0014] Figure 7 This is a graph showing an example of the output of pulse-driven infrared light.

[0015] Figure 8 1 is a schematic diagram showing a state in which the spot size of infrared light emitted from the first laser diode is adjusted by the first lens.

[0016] Fig. 9 : is a graph showing the relationship between the light emitting area width and the beam diameter at the lens when the angular resolution θ is set to 0.1°.

[0017] Fig.10 This is a schematic plan view showing a state where a cover of the optical module according to the second embodiment is removed.

[0018] Fig.11 This is a schematic side view of the optical module according to the second embodiment.

[0019] Fig.12 It is shown Fig.10 The optical module shown is a perspective view of the appearance of the optical module with the cover removed.

[0020] Fig.13 This is a schematic plan view of an optical module according to the third embodiment.

[0021] Fig.14 This is a schematic plan view showing a state where a cover of the optical module according to the third embodiment is removed.

[0022] Fig.15 yes Fig.14 The optical module is shown in a three-dimensional diagram.

[0023] Fig.16 This is a schematic plan view showing a state where a cover of the optical module according to the fourth embodiment is removed.

[0024] Fig.17 yes Fig.16 The optical module is shown in a three-dimensional diagram.

[0025] Fig.18 1 is a schematic perspective view showing an optical module in which a convex lens for focusing light is embedded in an incident window.

[0026] Fig.19 yes Fig.18 A simplified top view of the optical module is shown. DETAILED DESCRIPTION

[0027] [Technical Problems to be Solved by the Present Disclosure]

[0028] When a laser diode that emits laser light is used as a distance measuring sensor, the laser light emitted is controlled so as to become a pulse wave. When emitting a pulse wave, it is required that the control circuit used be easy to design and the output of the laser diode be stable.

[0029] Therefore, one of the objects is to provide an optical module that can easily realize circuit design and stabilize the output of a laser diode.

[0030] [Effects of the present disclosure]

[0031] According to such an optical module, it is possible to realize stable output of the laser diode while facilitating circuit design.

[0032] [Description of Embodiments of the Present Disclosure]

[0033] First, implementation aspects of the present disclosure are listed for description.

[0034] (1) The optical module involved in the present disclosure comprises: a laser diode that emits laser light; a scanning unit that has a reflective mirror that reflects the laser light and swings the reflective mirror to output the laser light to the outside; a protective container that has a transmission window for transmitting the laser light and surrounds the laser diode and the scanning unit; a control unit that controls so that the laser light becomes a pulse wave; and an electronic temperature adjustment module that adjusts the temperature of the laser diode and the scanning unit.

[0035] According to such an optical module, the pulse wave laser emitted from the laser diode can be used as a distance measuring sensor. That is, the distance to the object can be calculated and measured using the time of emitting the laser by pulse driving, the time from emitting the pulse wave laser from the laser diode to receiving the reflected light of the object, and the speed of the laser known in advance. In this case, the two-dimensional distance measurement can be performed by scanning the emitted laser by the scanning unit.

[0036] In a laser diode that emits a pulse wave laser, if you want to shorten the drive cycle of the laser diode while maintaining a small duty cycle in order to ensure stable driving of the laser diode, the pulse width becomes smaller. If the pulse width becomes extremely small, it becomes difficult to design a drive circuit that controls the pulse wave. If the pulse width is increased to a certain extent, the design of the drive circuit becomes easier, but the duty cycle becomes larger. In this way, the heat generated by the laser diode becomes larger, and it is difficult to output stably from the laser diode.

[0037] According to the optical module disclosed in the present invention, since it includes an electronic temperature adjustment module for adjusting the temperature of the laser diode, the electronic temperature adjustment module is driven when the optical module is in operation, so that the heat generation of the laser diode can be suppressed and the temperature can be controlled. In this way, the output from the laser diode can be stabilized while the pulse width is increased to a certain extent. In addition, since the heat generation of the laser diode can be suppressed, it is also possible to achieve a high output of the laser diode from the perspective of increasing the measurement distance, etc. Furthermore, since the electronic temperature adjustment module also adjusts the temperature of the scanning unit, the operation of the scanning unit can be stabilized regardless of the ambient temperature. Therefore, according to such an optical module, the output of the laser diode can be stabilized while the circuit design is easy to achieve.

[0038] (2) In the above (1), the duty cycle of the pulse wave may be greater than 0.1% and less than 10%. By adopting such a configuration, the pulse width can be increased while the peak value of the output value of the pulse wave is controlled within the limit of eye safety (level 1). Examples of the duty cycle of the pulse wave include 0.2% of the pulse width of 20 nanoseconds when the driving frequency of the laser diode is set to 100 kHz, or 0.5% of the pulse width of 50 nanoseconds when the driving frequency of the laser diode is set to 100 kHz.

[0039] (3) In the above (1) or (2), a plurality of laser diodes may be provided. The optical module may also include a filter for combining the laser beams emitted from the plurality of laser diodes. By adopting such a configuration, a plurality of laser diodes can be combined to achieve high output, thereby increasing the measurement distance and improving the SN ratio.

[0040] (4) In any of the above (1) to (3), at least one of the plurality of laser diodes may emit infrared light. Even if the heat generated by the laser diode emitting infrared light is large, the output from the laser diode can be stably obtained.

[0041] (5) In any of the above (1) to (4), at least one of the plurality of laser diodes may emit visible light. By adopting such a configuration, it can also be used for distance measurement in water.

[0042] (6) In any one of the above (1) to (5), a lens for adjusting the spot size of the laser light may be further provided. With such a configuration, laser light having a desired spot size can be emitted from the optical module.

[0043] (7) In any of the above (1) to (6), the width of the light emitting area of ​​the laser diode laser may be 50 μm or less. By adopting such a structure, the spot size can be reduced, the optical loss in the scanning mirror can be reduced, and the laser can be efficiently emitted. In addition, a multi-mode laser diode can be used, and high output can be achieved.

[0044] (8) In any of the above (1) to (7), the width of the light emitting region of the laser light of the laser diode may be 30 μm or less. By adopting such a configuration, the laser light can be emitted more efficiently.

[0045] (9) In any of the above (1) to (8), a photodiode may be further provided, the photodiode receiving reflected light of the laser light output to the outside of the protective container after being reflected by the object. By adopting such a configuration, the difference between the emission time of the laser light emitted by the laser diode and the reception time of the laser light received by the photodiode can be calculated.

[0046] (10) In the above (9), the photodiode may receive the reflected light from the reflector. By adopting such a structure, the device structure can be made more compact and miniaturized.

[0047] (11) In the above (9) or (10), an incident window for incident reflected light may be provided on the protective container. A convex lens for focusing reflected light so that the light receiving surface of the photodiode receives the reflected light may be embedded in the incident window. According to such a configuration, the reflected light from the object can be focused by the convex lens so that the light receiving surface of the photodiode receives the reflected light efficiently, thereby further improving the accuracy of the measured distance.

[0048] (12) In any of the above (9) to (11), the temperature of the photodiode may be adjusted by the electronic temperature adjustment module. By adopting such a configuration, it is possible to suppress the performance change of the photodiode due to temperature, and improve the accuracy of the measured distance.

[0049] (13) In any of the above (9) to (12), the control unit may also calculate the distance to the object based on the time when the laser is emitted and the time when the photodiode receives the reflected light. By adopting such a configuration, the control unit can use the difference between the time when the laser diode emits the laser and the time when the photodiode receives the reflected light, and the speed of the laser that has been known in advance to calculate the distance to the object. Therefore, the distance can be measured simply and accurately while suppressing the influence of ambient light.

[0050] [Details of the embodiments of the present disclosure]

[0051] Next, embodiments of the optical module disclosed herein will be described with reference to the accompanying drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and their description will not be repeated.

[0052] (Implementation Method 1)

[0053] The optical module in the first embodiment of the present disclosure will be described. Figure 1 This is a perspective view of the appearance of the optical module according to the first embodiment. Figure 2 It is shown Figure 1 A schematic top view of the structure of the optical module is shown. Figure 3 It is shown in Figure 1 The illustrated light module is a schematic top view of a state in which a cover to be described below is removed. Figure 4 yes Figure 1 A simplified side view of the optical module is shown. Figure 4 , the cover is shown in a state cut along an XZ plane where a transmission window to be described later is located. Figure 5 It is shown Figure 1 The optical module shown is a three-dimensional view of the appearance of the state after the cover is removed. Figure 1 In FIG. 1 , a control unit to be described below is schematically shown by a single-dot chain line. Figure 1 and will be described below Fig.18 In other drawings, illustration of the control unit is omitted.

[0054] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The optical module 10a includes a base 11, a cover 12 as a protective container, a control unit 20, a laser diode 41a (first laser diode 41a), a lens 42a (first lens 42a), a filter 43a (first filter 43a), and a mirror drive mechanism 50 as a scanning unit including a scanning mirror 52 for scanning light. In this embodiment, the base 11 includes a flat support plate 13, a flat bottom plate 14, an electronic cooling module 30 as an electronic temperature adjustment module, a block portion (first block portion 17a), a mounting portion (first mounting portion 18a), and a base 65 to be described below. The thickness direction of the support plate 13 is represented by the Z direction.

[0055] The cover 12 is a cover portion welded to the support plate 13. The components arranged on the support plate 13 are surrounded and sealed by the support plate 13 and the cover 12. That is, the cover 12 as a protective container surrounds the first laser diode 41a, the first lens 42a, the first filter 43a, and the mirror drive mechanism 50.

[0056] The support plate 13 is rectangular in shape with rounded corners when viewed from the Z direction. Specifically, the support plate 13 is configured such that the length in the X direction is longer than the length in the Y direction.

[0057] The support plate 13 includes a first surface 13a orthogonal to the thickness direction, and a second surface 13b located opposite to the first surface 13a in the thickness direction. The first surface 13a and the second surface 13b are respectively surfaces perpendicular to the Z direction, that is, surfaces parallel to the XY plane. The cover 12 is configured to contact the first surface 13a. A light transmission window 15 is provided on the cover 12. The first laser diode 41a, the first lens 42a, the first filter 43a and the mirror drive mechanism 50 arranged on the support plate 13 are hermetically sealed by the cover 12. The light transmission window 15 is provided on the upper side of the cover 12, that is, at a position opposite to the first surface 13a when the cover 12 is mounted on the support plate 13. A plurality of lead pins 16 are provided on the support plate 13 in a manner that penetrates the support plate 13 and protrudes from the first surface 13a and the second surface 13b.

[0058] The bottom plate 14 includes a first main surface 14a and a second main surface 14b of two main surfaces in the thickness direction. The first main surface 14a and the second main surface 14b are surfaces perpendicular to the Z direction, that is, surfaces parallel to the XY plane.

[0059] The electronic cooling module 30 adjusts the temperature of each component on the electronic cooling module 30. The electronic cooling module 30 is also called TEC (Thermo-Electric Cooler), and includes a heat sink 31, a heat absorbing plate 32, and a plurality of semiconductor columns 33. The electronic cooling module 30 is arranged on the support plate 13, specifically, on the first surface 13a of the support plate 13. The above-mentioned base plate 14 is arranged on the electronic cooling module 30. That is, the electronic cooling module 30 is arranged in a manner to be sandwiched between the support plate 13 and the base plate 14 in the Z direction. In the electronic cooling module 30, the heat sink 31 is arranged in a manner to contact the first surface 13a of the support plate 13. The heat absorbing plate 32 is arranged in a manner to contact the second main surface 14b of the base plate 14. The support plate 13 and the heat sink 31, and the base plate 14 and the heat absorbing plate 32 are respectively bonded by bonding materials not shown. The plurality of semiconductor columns 33 are composed of Peltier elements and are arranged at intervals in the X direction and the Y direction between the heat sink 31 and the heat absorbing plate 32. The plurality of semiconductor columns 33 are connected to the heat sink 31 and the heat absorbing plate 32, respectively. By energizing the electronic cooling module 30, the temperature of each component on the electronic cooling module 30 can be adjusted. By adjusting the current supplied to the electronic cooling module 30, it is easy to keep each component on the electronic cooling module 30 at a certain temperature for a long time, specifically, for example, 35°C.

[0060] The first block 17a is in a rectangular parallelepiped shape. The first block 17a is disposed on the first main surface 14a of the bottom plate 14. The first block 17a is configured so that the length in the X direction is shorter than the length in the Y direction when viewed in the Z direction. The first mounting portion 18a included in the base portion 11 is disposed in contact with the first block 17a. The first mounting portion 18a is disposed on the first block 17a.

[0061] The first laser diode 41a emits a first laser L1. The first laser L1 is, for example, infrared light. Regarding the wavelength emitted from the first laser diode 41a, for example, it can be a wavelength in a range of 700nm or more and less than 1100nm (first range), or a wavelength in a range of 1100nm or more and 1800nm ​​or less (second range). The longer the wavelength, that is, the laser light in the second range compared to the second range, the greater the acceptable emission limit of the laser light allowed by the eye, and therefore the greater the output can be set. Regarding the wavelength in the first range, typically, wavelengths of 830nm, 850nm, 905nm, and 940nm can be selected. Regarding the wavelength in the second range, typically, wavelengths of 1310nm and 1550nm can be selected.

[0062] The first laser diode 41a is placed on the first mounting portion 18a. The first laser diode 41a emits the first laser L1 in the Y direction (the direction of the arrow Y). The first laser diode 41a is a so-called multi-mode laser diode. The first laser diode 41a has a light emitting area on the emission end face, and the light emitting area has a long width in the X direction, and the first laser L1 is emitted from the light emitting area. The width of the light emitting area of ​​the first laser diode 41a is less than 50 μm. Specifically, the width of the light emitting area of ​​the first laser diode 41a is 30 μm. Here, the light emitting area width is the distance in the X direction of the current injection area defined by the shape of the electrode and the processing of the semiconductor constituting the first laser diode 41a.

[0063] The first lens 42a is placed above the heat absorbing plate 32, specifically, placed on the first main surface 14a of the bottom plate 14. The first lens 42a converts the spot size of the light emitted from the first laser diode 41a. Specifically, the first lens 42a is arranged in the emission direction of the first laser L1, and converts the first laser L1 into collimated light. In this way, the first lens 42a adjusts the spot size of the first laser L1 emitted from the first laser diode 41a.

[0064] The first filter 43a is placed above the heat absorbing plate 32, specifically, on the first main surface 14a of the bottom plate 14. The first filter 43a is arranged in the emission direction of the light emitted from the first laser diode 41a. The first filter 43a reflects the first laser L1 ( Figure 3 , Figure 4 L X ).

[0065] The optical module 10a includes a thermistor 21. The thermistor 21 is disposed on the first block 17a. The thermistor 21 is disposed near the first laser diode 41a. The thermistor 21 can be used to detect the temperature of the first block 17a and the area on the heat absorbing plate 32. The temperature detected by the thermistor 21 is used for temperature regulation by the electronic cooling module 30. It should be noted that the thermistor 21 can also be disposed on the base 65, and the mirror driving mechanism 50 described below is disposed on the base 65. In the case of a method for emphasizing the temperature adjustment of the mirror driving mechanism 50 by the electronic cooling module 30, the thermistor 21 can be disposed on the base 65. In addition, the thermistor 21 can also be disposed on the electronic cooling module 30, specifically, on the heat absorbing plate 32, and the first laser diode 41a and the mirror driving mechanism 50 are adjusted to appropriate temperatures by the electronic cooling module 30.

[0066] The mirror driving mechanism 50 included in the optical module 10 a is disposed on the electronic cooling module 30 , specifically, on the heat absorbing plate 32 . Figure 6 FIG. 1 is a schematic top view of the mirror drive mechanism 50 included in the optical module 10a. Figure 6 In other figures, the mirror driving mechanism 50 is simplified in illustration.

[0067] like Figure 6 As shown in FIG. 1 , the mirror driving mechanism 50 includes a frame 51, a disk-shaped scanning mirror 52 having a reflecting surface 55, and a support portion 53 for supporting the scanning mirror 52. The scanning mirror 52 is configured to be able to swing around a first swing axis 59a and a second swing axis 59b, each indicated by a single-dot chain line. The first swing axis 59a is a first swing axis 59a extending along a first axis 59b. Figure 6 The second swing axis 59b is an imaginary axis extending in the direction D2 of Figure 6 The imaginary axis extending in the direction D1 in FIG. The direction D1 is orthogonal to the direction D2. It should be noted that when assembling the optical module 10a, regarding the direction in which the mirror drive mechanism 50 is installed, the direction indicated by the arrow D1 is taken as Figure 1 The direction indicated by the arrow X shown in the above description is taken as the direction indicated by the arrow D2. Figure 1 The direction indicated by arrow Y shown in etc.

[0068] The frame 51 is provided with a first through hole 57a, and a support portion 53 for supporting the scanning mirror 52 is provided in the first through hole 57a. A second through hole 57b is provided in the support portion 53. The scanning mirror 52 is supported by a pair of thin rod-shaped shaft portions 54a and 54b so as to be able to swing around a second swing axis 59b indicated by a single-dot chain line in the second through hole 57b. When the scanning mirror 52 swings around the second swing axis 59b, four piezoelectric elements 56a, 56b, 56c, and 56d attached to the support portion 53 are used.

[0069] The support portion 53 is plate-shaped. The support portion 53 includes a plurality of first portions 61a, 61b, 61c, 61d, 61e, 61f, 61g, and 61h extending in the D1 direction, respectively. The support portion 53 also includes a plurality of second portions 62a, 62b, 62c, 62d, 62e, and 62f connecting adjacent first portions 61a to 61h, respectively. The support portion 53 also includes connecting portions 63a and 63b connecting the support portion 53 and the frame portion 51. The support portion 53 also includes a mounting portion 58, and the scanning mirror 52 is mounted on the mounting portion 58 via shaft portions 54a and 54b. The support portion 53 also includes connecting portions 63c and 63d connecting the first portions 61d and 61h and the mounting portion 58. The second portions 62a to 62f alternately connect the first ends of the two ends in the length direction of the adjacent first portions 61a to 61h to each other and the second ends to each other. Piezoelectric elements 64a, 64b, 64c, 64d, 64e, 64f, 64g, and 64h are attached to the first portions 61a to 61h, respectively. When the scanning mirror 52 swings around the first swing axis 59a, the piezoelectric elements 64a to 64h are used. As the piezoelectric elements 56a to 56d and 64a to 64h, for example, piezoelectric elements are used. The support portion 53 has a so-called zigzag structure.

[0070] The mirror driving mechanism 50 adjusts the voltage supplied to the piezoelectric elements 56a to 56d and 64a to 64h, and causes the scanning mirror 52 to swing around the first swing axis 59a and the second swing axis 59b as the center axis of the swing. Figure 6 The diameter R is represented by .

[0071] The mirror drive mechanism 50 is disposed on a base 65. The base 65 is composed of a triangular prism-shaped member. In this case, the mounting surface on which the mirror drive mechanism 50 is mounted is inclined relative to the first surface 13a. That is, the reflection surface of the scanning mirror 52 is inclined relative to the optical axis of the first laser L1 emitted from the first laser diode 41a.

[0072] The control unit 20 controls the pulse driving of the first laser diode 41a, controls the electronic cooling module 30, and controls the mirror driving mechanism 50. In other words, the control unit 20 controls the first laser diode 41a so that the first laser light L1 emitted from the first laser diode 41a becomes a pulse wave. Figure 7 : is a graph showing an example of the output of the first laser L1 driven by pulse. Figure 7 In the figure, the vertical axis represents the light output of the laser and the horizontal axis represents time. Figure 7 The control unit 20 periodically sends a signal to control the operation of the first laser diode 41a so that a pulse wave with a certain pulse width is emitted from the first laser diode 41a. It should be noted that the duty cycle is a value obtained by dividing the pulse width by the driving period. In this embodiment, the duty cycle is greater than 0.1% and less than 10%. Specifically, the duty cycle is 0.5%.

[0073] The scanning light L reflected by the swinging scanning mirror 52 R , L S , L T It is emitted through the window 15. Figure 4 The first laser L1 is reflected by the object and becomes reflected light. The control unit 20 can use the time of emitting the first laser L1, the time until the reflected light is received, and the speed of the first laser L1 (infrared light) known in advance to measure the distance to the object. In this case, by scanning the first laser L1 with the mirror drive mechanism 50, two-dimensional distance measurement can be performed.

[0074] According to the optical module 10a disclosed in the present invention, since it includes an electronic cooling module 30 for adjusting the temperature of the first laser diode 41a, the electronic cooling module 30 is driven when the optical module 10a is in operation, and the heat generation of the first laser diode 41a can be suppressed to control the temperature. In this way, the output from the first laser diode 41a can be stabilized while increasing the pulse width to a certain extent. In addition, since the heat generation of the first laser diode 41a can be suppressed, the high output of the first laser diode 41a can also be achieved from the perspective of increasing the measurement distance. Furthermore, since the electronic cooling module 30 also adjusts the temperature of the mirror drive mechanism 50, the operation of the mirror drive mechanism 50 can be stabilized regardless of the ambient temperature. For example, the deflection angle of the scanning mirror 52 can be stabilized. Therefore, according to such an optical module 10a, the output of the first laser diode 41a can be stabilized while the circuit design is easy to achieve.

[0075] In the present embodiment, the first lens 42a for adjusting the spot size of the first laser light L1 emitted from the first laser diode 41a is provided. Therefore, the first laser light L1 having a desired spot size can be emitted from the optical module 10a.

[0076] In this embodiment, the light emitting area width of the first laser L1 of the first laser diode 41a is 50 μm or less. Therefore, the spot size can be reduced, the optical loss in the scanning mirror 52 can be reduced, and the first laser L1 can be efficiently emitted. In addition, a multi-mode laser diode can be used to achieve high output.

[0077] Figure 8 Schematic diagram showing a state in which the spot size of the first laser light L1 emitted from the first laser diode 41a is adjusted by the first lens 42a. Figure 8 , the first laser 44 emitted from the first laser diode 41a is diffused light and reaches the first lens 42a at a distance S1 from the focal length of the lens. If the beam diameter falling within the effective diameter of the first lens 42a and the spot size is adjusted is set to diameter W1, the first laser 45 passing through the first lens 42a becomes a beam diameter W2 corresponding to the beam diameter W1 at the first lens 42a at a distance S2. As the measurable distance S2, for example, within 100m is selected for industrial use, and 200m or more and 300m or less is selected for vehicle use.

[0078] If the beam diameter at the scanning mirror 52 is set to diameter W3, the optical loss in the scanning mirror 52 can be reduced when the diameter W3 is less than the diameter R of the scanning mirror 52. The beam diameter W3 at the scanning mirror 52 is approximately equal to the beam diameter W1 at the first lens 42a, and this value is expressed by the following approximate formula.

[0079] Scanning mirror diameter R≈beam diameter at lens W1≈2×light emitting area width×tan(θ h / 2) / tanθ

[0080] Angle θ h The emission angle of the outgoing light beam in the width direction of the light emitting area of ​​the first laser diode 41a is shown in Figure 8 The angle θ represents the angular resolution. It should be noted that the actual diameter R of the scanning mirror 52 may be less than 10 mm.

[0081] Fig. 9 is a graph showing the relationship between the width of the light emitting area and the beam diameter at the lens when the angular resolution θ is set to 0.1°. Fig. 9 In the figure, the vertical axis represents the beam diameter at the lens, and the horizontal axis represents the width of the light-emitting area. Fig. 9, when the width of the light emitting area is 70 μm, the beam diameter at the lens is 12 mm. Thus, for example, when 10 mm is selected as the diameter R of the scanning mirror 52, the beam diameter W2 cannot fall within the diameter R of the scanning mirror 52. This is a particularly significant problem when the first lens 42a and the mirror drive mechanism 50 are housed in a protective container as in the optical module 10a of the present disclosure, and a configuration is required to reduce optical loss while miniaturizing components directly related to the miniaturization of the optical module.

[0082] By setting the light emission area width of the first laser L1 of the first laser diode 41a to 50 μm or less, the beam diameter at the lens can be set to 10 mm or less, and the optical loss in the scanning mirror 52 can be reduced. Therefore, the first laser L1 can be emitted efficiently.

[0083] (Implementation Method 2)

[0084] Embodiment 2 as another embodiment will be described. Fig.10 This is a schematic plan view showing a state where a cover of the optical module according to the second embodiment is removed. Fig.11 This is a schematic side view of the optical module according to the second embodiment. Fig.12 It is shown Fig.10 The optical module shown is a stereoscopic view of the appearance of the optical module with the cover removed. The optical module in Embodiment 2 basically has the same structure as that in Embodiment 1 and has the same effect. However, the optical module in Embodiment 2 is different from that in Embodiment 1 in that the number of laser diodes, lenses, and filters is increased.

[0085] Reference Fig.10 , Fig.11 and Fig.12 The optical module 10b of embodiment 2 includes a laser diode 41b (a second laser diode 41b), a lens 42b (a second lens 42b) and a filter 43b (a second filter 43b). The second lens 42b adjusts the spot size of the second laser L2 emitted from the second laser diode 41b. The second filter 43b reflects the second laser L2 emitted from the second laser diode 41b. The second laser diode 41b emits the second laser L2 by pulse driving. The second laser diode 41b emits the second laser L2 in the Y direction (the direction of the arrow Y). The second laser L2 is, for example, infrared light. Here, the wavelength of the second laser L2 may also be different from the wavelength of the first laser L1. For example, the wavelength of the first laser L1 may be set to 830nm, and the wavelength of the second laser L2 may be set to 940nm.

[0086] The control unit 20 controls so that the pulse drive of the first laser L1 is the same as the pulse drive of the second laser L2. That is, pulse waves are emitted from both the first laser diode 41a and the second laser diode 41b at the same timing. The first filter 43a is a wavelength selective filter that reflects the first laser L1 and transmits the second laser L2. That is, it reflects the first laser L1 with a wavelength of 830nm and transmits the second laser L2 with a wavelength of 940nm. In this way, the first filter 43a combines the first laser L1 and the second laser L2 to form a combined light L Y The combined light L Y It travels in the Y direction and is incident on the scanning mirror 52 .

[0087] According to the present embodiment, a plurality of laser diodes can be combined to realize high output, thereby achieving an increase in the measuring distance and an improvement in the SN ratio.

[0088] It should be noted that, in the above embodiment, the wavelength of the first laser L1 may be set to 1310 nm, and the wavelength of the second laser L2 may be set to 1550 nm. In addition, the wavelength of the first laser L1 may be set to 905 nm, and the wavelength of the second laser L2 may be set to 1550 nm. That is, the wavelengths of the lasers emitted from the laser diodes may be different to perform the multiplexing.

[0089] In addition, in the above-mentioned embodiment, the polarization direction of the first laser L1 and the polarization direction of the second laser L2 can also be configured to be orthogonal. In this case, a 1 / 2 wavelength plate is prepared and arranged before or after the second lens 42b. It is also possible to combine the polarization directions by rotating the polarization directions by 90 degrees in this way by the first filter 43a. In addition, a cube-shaped polarization beam splitter, for example, can be configured instead of the first filter 43a. With this configuration, even when the wavelength of the first laser L1 is the same as the wavelength of the second laser L2, it is possible to combine the first filter 43a to achieve high output.

[0090] Again, refer to the above Fig. 9 In order to make the beam diameter at the lens less than 10 mm, it is best to set the light emitting area width to less than 50 μm, but increasing the diameter of the scanning mirror 52 is difficult from the perspective of deflection angle and durability. That is, the beam diameter at the lens can be, for example, less than 6 mm. In this way, the light emitting area width can be less than 30 μm. The shorter the light emitting area width, the lower the output of the laser diode, and the shorter the distance that can be measured.

[0091] However, in this embodiment, two laser diodes are combined to achieve an increase in output, that is, high output. In this case, for example, a plurality of single-mode laser diodes whose light emission area width of the laser diodes is 5 μm or less can be mounted and used.

[0092] It should be noted that, in the above embodiment, the number of laser diodes is set to two, but it is not limited thereto, and the number of laser diodes may be set to three or more. Here, the light emitting area width of the laser diode laser may be 10 μm or more. By adopting such a configuration, it is possible to ensure an output effective for distance measurement without excessively increasing the number of laser diodes.

[0093] (Implementation method 3)

[0094] Embodiment 3 as another embodiment will be described. Fig.13 This is a schematic plan view of an optical module according to the third embodiment. Fig.14 This is a schematic plan view showing a state where a cover of the optical module according to the third embodiment is removed. Fig.15 yes Fig.14 The optical module in Embodiment 3 basically has the same structure as Embodiment 2 and has the same effect. However, the optical module in Embodiment 3 is different from Embodiment 2 in that it has a photodiode for receiving reflected light.

[0095] Reference Fig.13 , Fig.14 and Fig.15 The optical module 10c of the third embodiment includes a photodiode 22 for receiving reflected light. The photodiode 22 has a light receiving surface 23, and the light receiving surface 23 is arranged to face the Z direction, that is, the surface provided with the transmission window 15. As the material of the photodiode 22, when the wavelength of the first laser L1 is 830nm and the wavelength of the second laser L2 is 940nm, for example, Si (silicon) is selected. Since the material of such a photodiode 22 is silicon, the characteristics as a photodiode are good. The photodiode 22 receives the reflected light after the laser emitted to the outside of the cover 12 as a protective container is reflected by the object.

[0096] It should be noted that the cover 12 is provided with an incident window 19 for receiving reflected light. In addition, the photodiode 22 is arranged on the electronic cooling module 30 and the temperature is adjusted. The control unit 20 calculates the distance to the object based on the time when the first laser L1 and the second laser L2 are emitted and the time when the reflected light is received by the photodiode 22.

[0097] According to this embodiment, in the control unit 20, the difference between the time of emitting the first laser L1 and the second laser L2 and the time of receiving the reflected light by the photodiode 22, and the speed of the laser (infrared light in this case) that has been known in advance can be used to calculate the distance to the object. Therefore, the device structure can be made compact and miniaturization can be easily achieved. In addition, since the temperature of the photodiode 22 is adjusted by the electronic cooling module 30, the performance change of the photodiode 22 due to the temperature can be suppressed, and the accuracy of the measured distance can be improved.

[0098] In the above embodiment, a lens for focusing light may be provided at any of the incident window 19 itself, the inside of the incident window 19, and the outside of the incident window 19. With such a configuration, reflected light can be efficiently incident on the light receiving surface 23 of the photodiode 22.

[0099] Fig.18 1 is a schematic perspective view showing an optical module 10 e in which a convex lens for focusing light is embedded in an incident window. Fig.19 yes Fig.18 A schematic top view of the optical module 10e is shown. Fig.18 and Fig.19 The cover 12 as a protective container of the optical module 10e according to the present embodiment is provided with a transmission window 15 and an incident window 19 for incident reflected light which is circular when viewed in the Z direction. A convex lens 71 is embedded in the incident window 19 to focus the reflected light so that the light receiving surface 23 of the photodiode 22 receives the reflected light. The reflected light reflected by the object and reaching the convex lens 71 is focused by the convex lens 71 and reaches the light receiving surface 23 of the photodiode 22. That is, the light receiving surface 23 of the photodiode 22 receives the reflected light focused by the convex lens 71.

[0100] According to such a configuration, the reflected light from the object can be condensed by the convex lens 71 and efficiently received by the light receiving surface 23 of the photodiode 22 , so that the accuracy of the measured distance can be further improved.

[0101] In the above embodiment, the transmission window 15 and the incident window 19 are provided separately, but the present invention is not limited thereto, and a single integrated window may be provided.

[0102] In the above embodiment, when the wavelength of the first laser L1 is set to 1310 nm and the wavelength of the second laser L2 is set to 1550 nm, InGaAs (indium gallium arsenide) may be used as the material of the photodiode 22. In addition, when the wavelength of the first laser L1 is set to 905 nm and the wavelength of the second laser L2 is set to 1550 nm, both the photodiode 22 made of Si and the photodiode 22 made of InGaAs may be mounted.

[0103] (Implementation 4)

[0104] Embodiment 4 as another embodiment will be described. Fig.16 This is a schematic plan view showing a state where a cover of the optical module according to the fourth embodiment is removed. Fig.17 yes Fig.16 The optical module in the fourth embodiment basically has the same structure as the third embodiment and has the same effect. However, the optical module in the fourth embodiment is different from the third embodiment in that the reflected light is incident from the transmission window and the photodiode receives the reflected light after being reflected by the scanning mirror.

[0105] Reference Fig.16 and Fig.17 The optical module 10d of the fourth embodiment includes a reflector 24 having a through hole 25, a lens 26, and a photodiode 27 having a light receiving surface 28. The reflector 24 is arranged at the position of the multiplexed light L Y Specifically, the reflector 24 is disposed between the first filter 43a and the scanning mirror 52. The combined light L Y The reflected light L passes through the through hole 25, is emitted from the optical module 10d, and is reflected by the object. Z The combined light L Y The reflected light L passes through the reflector 24. Z The light reaches the light receiving surface 28 of the photodiode 27. The photodiode 27 is arranged so that the light receiving surface 28 faces the reflector 24 in the Y direction. In this embodiment, the incident window 19 described in Embodiment 3 is not provided.

[0106] Combined Wavelength L Y The reflected light L emitted from the transmission window 15 and reflected by the object reaches the scanning mirror 52 through the through hole 25. Z The incident light enters from the transmission window 15. Then, it is reflected by the scanning mirror 52 and further reflected by the reflecting mirror 24. In this case, since the scanning mirror 52 swings, most of it is reflected toward the area of ​​the reflecting mirror 24 where the through hole 25 is not provided, so that the reflected light L Z The reflected light L reaches the light receiving surface 28 of the photodiode 27 via the lens 26. In this way, the photodiode 27 receives the reflected light L Z The control unit 20 generates the first laser beam L1 and the second laser beam L2 according to the timing of emitting the first laser beam L1 and the second laser beam L2 and the timing of receiving the reflected light L Z time to calculate the distance to the object.

[0107] According to this embodiment, the device configuration can be further miniaturized. Furthermore, since the disturbance light reaching the light receiving surface 28 of the photodiode 27 is reduced, the SN ratio can be improved.

[0108] (Other embodiments)

[0109] In the above-mentioned embodiment, the distance is calculated by the control unit, but the present invention is not limited to this. The control unit may control the pulse drive, and the distance calculation may be performed outside the control unit.

[0110] In the above-mentioned embodiment, the base on which the mirror driving mechanism is arranged adopts a configuration in which the mirror driving mechanism is arranged on an inclined surface provided on the base, but the present invention is not limited thereto, and the base may also have a surface parallel to the first surface of the support plate, and the mirror driving mechanism may be arranged on the parallel surface. In this case, other reflecting mirrors may also be arranged at appropriate positions so that the laser is incident on the scanning mirror of the mirror driving mechanism.

[0111] In the above embodiment, the laser diode and the mirror drive mechanism are arranged on the electronic cooling module, but the present invention is not limited thereto, and the following structure may be adopted: that is, a plurality of electronic cooling modules are provided, and the electronic cooling module on which the laser diode is arranged and the electronic cooling module on which the mirror drive mechanism is arranged may be separately included. By adopting such a structure, the temperature of each component can be strictly adjusted, and the distance measurement with higher accuracy can be performed.

[0112] In the above-mentioned embodiment, the laser diode uses a multi-mode laser diode, but it is not limited to this, and a single-mode laser diode may also be used. In particular, in the case shown in Embodiment 2, by using a plurality of single-mode laser diodes, it is possible to increase the output. In addition, by using a single-mode laser diode, it is possible to reduce the beam diameter and achieve higher resolution.

[0113] In the above embodiment, a laser diode emitting infrared light is used, but it is not limited thereto, and all or part of the plurality of laser diodes may also use laser diodes emitting visible light. For example, for distance measurement in water, a laser diode emitting green light with a wavelength of 515 nm to 530 nm that is not easily absorbed by water, or a laser diode emitting blue light with a wavelength of 430 nm to 460 nm may be used.

[0114] It should be understood that the embodiments disclosed herein are examples in all points and are not restrictive in any respect. The scope of the present invention is defined by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0115] Description of Reference Numerals

[0116] 10a, 10b, 10c, 10d, 10e optical module; 11 base; 12 cover (protective container); 13 support plate; 13a first surface; 13b second surface; 14 bottom plate; 14a first main surface; 14b second main surface; 15 transmission window; 16 lead pin; 17a block (first block); 17b block (second block); 18a mounting portion (first mounting portion); 18b mounting portion (second mounting portion); 19 incident window; 20 control portion; 21 thermistor; 22, 27 photodiode; 23, 28 light receiving surface; 24 reflector; 25 through hole; 26 lens; 30 electronic cooling module (electronic temperature adjustment module); 31 heat sink; 32 heat absorbing plate; 33 semiconductor column; 41a laser diode (first laser diode); 41b laser diode (second laser diode); 42a lens (first lens); 42b lens (second 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 54, 55, 56, 56, 56, 56, 56, 56, 56, 54, 54, 55, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 111, 112, 113, 114, 115, 116, 117, 118, 119, 119, 120, 121 through hole; 57b second through hole; 58 mounting portion; 59a first swing axis; 59b second swing axis; 61a, 61b, 61c, 61d, 61e, 61f, 61g, 61h first portion; 62a, 62b, 62c, 62d, 62e, 62f second portion; 63a, 63b connecting portion; 63c, 63d connecting portion; 65 base; 71 convex lens; D1, D2, X, Y, Z arrows; θ h Angle; L1 first laser; L2 second laser; L X First laser; L Y Combined wave light; L R , L S , L T Scanning light; L Z Reflected light; R, W1, W2, W3 diameters; S1, S2 distances; θ angle (angular resolution).

Claims

1. An optical module, comprising: Laser diode, emitting laser light; a scanning unit having a reflection mirror for reflecting the laser light, and outputting the laser light to the outside by swinging the reflection mirror; A protective container having a transmission window for the laser to transmit and surrounding the laser diode and the scanning unit; A control unit that controls so that the laser light becomes a pulse wave; as well as The electronic temperature adjustment module adjusts the temperature of the laser diode and the scanning unit.

2. The optical module according to claim 1, wherein: The duty ratio of the pulse wave is greater than 0.1% and less than 10%.

3. The optical module according to claim 1 or 2, wherein: The optical module includes a plurality of the laser diodes. The optical module further includes a filter for combining the laser beams emitted from the plurality of laser diodes.

4. The optical module according to any one of claims 1 to 3, wherein: At least one of the plurality of laser diodes emits infrared light.

5. The optical module according to any one of claims 1 to 4, wherein: At least one of the plurality of laser diodes emits visible light.

6. The optical module according to any one of claims 1 to 5, wherein: The optical module further includes a lens for adjusting a spot size of the laser light.

7. The optical module according to any one of claims 1 to 6, wherein: The width of the light emitting area of ​​the laser is less than 50 μm.

8. The optical module according to any one of claims 1 to 7, wherein: The width of the light emitting area of ​​the laser is less than 30 μm.

9. The optical module according to any one of claims 1 to 8, wherein: The optical module further includes a photodiode configured to receive reflected light of the laser light output to the outside of the protective container after being reflected by an object.

10. The optical module according to claim 9, wherein: The photodiode receives reflected light from the reflector.

11. The optical module according to claim 9 or 10, wherein: The protective container is provided with an incident window for the reflected light to be incident on. A convex lens is embedded in the incident window to collect the reflected light so that the reflected light is received by the light receiving surface of the photodiode.

12. The optical module according to any one of claims 9 to 11, wherein: The temperature of the photodiode is adjusted by the electronic temperature adjustment module.

13. The optical module according to any one of claims 9 to 12, wherein: The control unit calculates the distance to the object based on the time when the laser light is emitted and the time when the photodiode receives the reflected light.

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