A multi-wavelength laser beam combining emission system for time-of-flight sensing

Abstract

The application provides a kind of multi-wavelength laser beam combination emission system for time-of-flight sensing, comprising first and second collimation modules, including first and second laser diodes, first and second aspherical lenses and first and second cylindrical lenses, the first and second laser diodes are used to emit first and second collimated beams, the first and second aspherical lenses are used for fast-axis collimation, and the first and second cylindrical lenses are used for slow-axis collimation;Beam combination module for combining the first and second collimated beams into a mixed collimated beam, the beam combination module includes a color combiner, and the different surfaces of the color combiner are coated with narrow-band reflective films;Beam shrinking / expanding module for adjusting the diameter of the mixed collimated beam, the beam combination module includes a front group of convex lenses and a rear group of concave lenses coated with antireflection films corresponding to the wavelengths of the collimated beams.The multi-wavelength laser beam combination emission system for time-of-flight sensing provided by the application can effectively collimate laser beams and improve the detection efficiency of the system.

Description

Technical Field

[0001] This invention relates to the field of photoelectric detection technology, and in particular to a multi-wavelength laser beam combining system for time-of-flight sensing. Background Technology

[0002] For time-of-flight sensing systems, the most commonly used light source is the laser diode (LD). Typically, an LD has different divergence angles along its fast axis (perpendicular to the junction plane) and slow axis (parallel to the junction plane). The beam output from an LD must be shaped before practical application, and existing optical systems struggle to collimate it.

[0003] Therefore, it is necessary to provide a multi-wavelength laser beam combining system for time-of-flight sensing to effectively solve the above problems. Summary of the Invention

[0004] This invention provides a multi-wavelength laser beam combining and emission system for time-of-flight sensing, which can effectively collimate the laser beam and improve the detection efficiency of the system.

[0005] This invention provides a multi-wavelength laser beam combining system for time-of-flight sensing, comprising:

[0006] The first collimation module includes a first laser diode, a first aspherical lens, and a first cylindrical lens. The first laser diode is used to emit a first collimated beam, the first aspherical lens is used for collimation of the fast axis, and the first cylindrical lens is used for collimation of the slow axis. The first surface of the first aspherical lens faces the first laser diode, and the second surface of the first aspherical lens faces the first cylindrical lens. The first surface of the first aspherical lens is planar, and the second surface of the first aspherical lens is spherical.

[0007] The second collimation module includes a second laser diode, a second aspherical lens, and a second cylindrical lens. The second laser diode is used to emit a second collimated beam, the second aspherical lens is used for collimation of the fast axis, and the second cylindrical lens is used for collimation of the slow axis. The first surface of the second aspherical lens faces the second laser diode, and the second surface of the second aspherical lens faces the second cylindrical lens. The first surface of the second aspherical lens is planar, and the second surface of the second aspherical lens is spherical.

[0008] A beam combining module is used to combine the first collimated beam and the second collimated beam into a mixed collimated beam. The beam combining module includes a color combining prism, and narrow-band reflective films are coated on different surfaces of the color combining prism.

[0009] A beam-shrinking / beam-expanding module is used to adjust the diameter of the mixed collimated beam. The beam-combining module includes a front convex lens and a rear concave lens, both of which are coated with anti-reflection films corresponding to the wavelength of the collimated beam.

[0010] Preferably, the surface profile sagitta of the first aspherical lens and the second aspherical lens is calculated using the following formula:

[0011]

[0012] Where z is the surface elevation at the corresponding position, r is the radial coordinate, c is the curvature of the surface, A is the aspherical coefficient, and i is a natural number.

[0013] Preferably, the numerical aperture (NA) of the first aspherical lens and the second aspherical lens is greater than 0.5.

[0014] Preferably, the focal lengths of the first aspherical lens and the second aspherical lens are calculated using the following formula:

[0015]

[0016] Where f is the focal length of the aspherical lens, D is the diameter of the target beam, and NA is the numerical aperture.

[0017] Preferably, the focal lengths of the first cylindrical lens and the second cylindrical lens are calculated using the following formula:

[0018]

[0019] Where f′ is the focal length of the cylindrical lens, D is the diameter of the target beam, and θ0 is the emission angle in the slow axis direction.

[0020] Preferably, the color-combining prism uses ultraviolet fused silica as the substrate.

[0021] Preferably, when the wavelengths of the first collimated beam and the second collimated beam are different, the two prism surfaces facing each other of the color combining prism are coated with narrow-band reflective films of corresponding different wavelengths.

[0022] Preferably, when the wavelengths of the first collimated beam and the second collimated beam are the same, the two orthogonal surfaces inside the color combining prism are coated with dichroic films of corresponding wavelengths.

[0023] Preferably, the front convex lens and the rear concave lens use ultraviolet fused silica as the substrate.

[0024] Preferably, the reflective bandwidth of the narrowband reflective film is ±10nm of the center wavelength.

[0025] Compared with the prior art, the technical solution of the embodiments of the present invention has the following beneficial effects:

[0026] This invention provides a multi-wavelength laser beam combining system for time-of-flight sensing, comprising a first collimation module including a first laser diode, a first aspherical lens, and a first cylindrical lens. The first laser diode emits a first collimated beam, the first aspherical lens collimates the fast axis, and the first cylindrical lens collimates the slow axis. A first surface of the first aspherical lens faces the first laser diode, and a second surface of the first aspherical lens faces the first cylindrical lens. The first surface of the first aspherical lens is planar, and the second surface of the first aspherical lens is spherical. A second collimation module includes a second laser diode, a second aspherical lens, and a second cylindrical lens. The second laser diode emits a second collimated beam, and the second aspherical lens... The first collimated beam is used for fast-axis collimation, and the second cylindrical lens is used for slow-axis collimation. The first surface of the second aspherical lens faces the second laser diode, and the second surface of the second aspherical lens faces the second cylindrical lens. The first surface of the second aspherical lens is planar, and the second surface of the second aspherical lens is spherical. A beam combining module is used to combine the first collimated beam and the second collimated beam into a mixed collimated beam. The beam combining module includes a color-combining prism, and narrow-band reflective films are coated on different surfaces of the color-combining prism. A beam shrinking / expanding module is used to adjust the diameter of the mixed collimated beam. The beam combining module includes a front convex lens and a rear concave lens, and the front convex lens and the rear concave lens are coated with anti-reflective films corresponding to the wavelength of the collimated beam, thereby effectively collimating the laser beam.

[0027] Furthermore, by setting the surface profile, numerical aperture, and focal length of the first and second aspherical lenses, as well as the focal lengths of the first and second cylindrical lenses, the laser beam can be collimated more effectively, thereby improving the detection efficiency of the system. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention, but not all embodiments. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A schematic diagram of a multi-wavelength laser beam combining system for time-of-flight sensing provided as an embodiment of the present invention;

[0030] Figure 2A schematic diagram of the optical path of the light source in a multi-wavelength laser beam combining emission system for time-of-flight sensing, provided as an embodiment of the present invention, on the fast and slow axes.

[0031] Figure 3 A schematic diagram of the collimated optical path of a multi-wavelength laser beam combining and transmitting system for time-of-flight sensing is provided as an embodiment of the present invention.

[0032] Figure 4 A schematic diagram of the beam combining optical path of a multi-wavelength laser beam combining emission system for time-of-flight sensing provided as an embodiment of the present invention;

[0033] Figure 5 A schematic diagram of another beam combining optical path for a multi-wavelength laser beam combining emission system for time-of-flight sensing, provided as an embodiment of the present invention;

[0034] Figure 6 A schematic diagram of the beam shrinking / expanding optical path of a multi-wavelength laser beam combining and transmitting system for time-of-flight sensing, provided as an embodiment of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0037] To address the problems existing in the prior art, this invention provides a multi-wavelength laser beam combining and emission system for time-of-flight sensing, which can effectively collimate the laser beam and improve the system's detection efficiency.

[0038] Figure 1 A schematic diagram of a multi-wavelength laser beam combining system for time-of-flight sensing provided as an embodiment of the present invention; Figure 2 A schematic diagram of the optical path of the light source in a multi-wavelength laser beam combining emission system for time-of-flight sensing, provided as an embodiment of the present invention, on the fast and slow axes. Figure 3 A schematic diagram of the collimated optical path of a multi-wavelength laser beam combining and transmitting system for time-of-flight sensing is provided as an embodiment of the present invention. Figure 4A schematic diagram of the beam combining optical path of a multi-wavelength laser beam combining emission system for time-of-flight sensing provided as an embodiment of the present invention; Figure 5 A schematic diagram of another beam combining optical path for a multi-wavelength laser beam combining emission system for time-of-flight sensing, provided as an embodiment of the present invention; Figure 6 A schematic diagram of the beam shrinking / expanding optical path of a multi-wavelength laser beam combining and transmitting system for time-of-flight sensing, provided as an embodiment of the present invention.

[0039] Now see Figures 1 to 6 This invention provides a multi-wavelength laser beam combining system for time-of-flight sensing, comprising:

[0040] The first collimation module includes a first laser diode, a first aspheric lens (ASPL), and a first cylindrical lens (CYL). The first laser diode is used to emit a first collimated beam, the first aspheric lens is used for collimation of the fast axis, and the first cylindrical lens is used for collimation of the slow axis. The first surface of the first aspheric lens faces the first laser diode, and the second surface of the first aspheric lens faces the first cylindrical lens. The first surface of the first aspheric lens is planar, and the second surface of the first aspheric lens is spherical.

[0041] The second collimation module includes a second laser diode, a second aspherical lens, and a second cylindrical lens. The second laser diode is used to emit a second collimated beam, the second aspherical lens is used for collimation of the fast axis, and the second cylindrical lens is used for collimation of the slow axis. The first surface of the second aspherical lens faces the second laser diode, and the second surface of the second aspherical lens faces the second cylindrical lens. The first surface of the second aspherical lens is planar, and the second surface of the second aspherical lens is spherical.

[0042] A beam combining module is used to combine the first collimated beam and the second collimated beam into a mixed collimated beam. The beam combining module includes a color combining prism, and narrow-band reflective films are coated on different surfaces of the color combining prism.

[0043] A beam-shrinking / beam-expanding module is used to adjust the diameter of the mixed collimated beam. The beam-combining module includes a front convex lens and a rear concave lens, both of which are coated with anti-reflection films corresponding to the wavelength of the collimated beam.

[0044] The aforementioned system can integrate multiple wavelength light sources into a single emission system, possessing similar beam characteristics. The beam combiner module can combine multiple light sources of the same wavelength onto the same optical axis, increasing the overall output power. The beam shrinking / expanding module can adjust the diameter of the mixed collimated beam, thereby reducing the system's detection blind zone.

[0045] In specific implementation, the surface profile sag of the first aspherical lens and the second aspherical lens is calculated using the following formula:

[0046]

[0047] Where z is the surface elevation at the corresponding position, r is the radial coordinate, c is the curvature of the surface, A is the aspherical coefficient, and i is a natural number.

[0048] In specific implementations, the numerical aperture (NA) of the first and second aspherical lenses is greater than 0.5. Because the laser diode has a large divergence angle on the fast axis, a larger numerical aperture is required for collimation.

[0049] In specific implementation, the focal lengths of the first aspherical lens and the second aspherical lens are calculated using the following formula:

[0050]

[0051] Where f is the focal length of the aspherical lens, D is the diameter of the target beam, and NA is the numerical aperture. The focal length f of the first and second aspherical lenses is determined by the diameter D of the target beam.

[0052] In specific implementation, the focal lengths of the first cylindrical lens and the second cylindrical lens are calculated using the following formula:

[0053]

[0054] Where f′ is the focal length of the cylindrical lens, D is the diameter of the target beam, and θ0 is the emission angle in the slow axis direction.

[0055] In practice, after collimation by aspherical and cylindrical lenses, the collimation system can output a collimated beam with a divergence angle of less than 0.1 mrad.

[0056] In practical implementation, a color-combining prism is required to combine the first and second collimated beams into a single beam. Since the light source requiring beam combining is a laser source, the color-combining prism uses ultraviolet fused silica as its substrate and has narrow-band reflective films coated on different surfaces to combine beams of different wavelengths.

[0057] In specific implementations, when the wavelengths of the first collimated beam and the second collimated beam are different, the two prism surfaces facing the color combining prism are coated with corresponding narrowband reflective films of different wavelengths. For example, if the wavelength of the first collimated beam is 632nm and the wavelength of the second collimated beam is 905nm, the two prism surfaces facing the color combining prism are coated with a 632nm narrowband reflective film and a 905nm narrowband reflective film, respectively, so that the 632nm first collimated beam and the 905nm second collimated beam become a 632nm / 905nm mixed collimated beam.

[0058] In specific implementations, when the wavelengths of the first and second collimated beams are the same, the two orthogonal surfaces inside the color-combining prism are coated with dichroic films of corresponding wavelengths. For example, if the wavelengths of both the first and second collimated beams are 905 nm, and the two orthogonal surfaces inside the color-combining prism are coated with 905 nm dichroic films, it ensures that one of the first and second collimated beams is reflected while the other is projected, allowing the first and second collimated beams to be integrated into the same optical path to form a mixed collimated beam.

[0059] In specific implementations, the front convex lens and the rear concave lens use ultraviolet fused silica as the substrate. The beam contraction / expansion module uses a Kepler architecture, and the front convex lens and the rear concave lens are coated with antireflective films corresponding to the collimated beam wavelength to avoid direct ablation of the wafer by the laser.

[0060] In a specific implementation, the reflective band width of the narrowband reflective film is ±10nm of the center wavelength.

[0061] In summary, the present invention provides a multi-wavelength laser beam combining and emission system for time-of-flight sensing, comprising a first collimation module including a first laser diode, a first aspherical lens, and a first cylindrical lens. The first laser diode is used to emit a first collimated beam, the first aspherical lens is used for collimation along the fast axis, and the first cylindrical lens is used for collimation along the slow axis. The first surface of the first aspherical lens faces the first laser diode, and the second surface of the first aspherical lens faces the first cylindrical lens. The first surface of the first aspherical lens is planar, and the second surface of the first aspherical lens is spherical. The second collimation module includes a second laser diode, a second aspherical lens, and a second cylindrical lens. The second laser diode is used to emit a second collimated beam, the second aspherical lens is planar, and the second surface of the first aspherical lens is spherical. A planar lens is used for collimation along the fast axis, and a second cylindrical lens is used for collimation along the slow axis. The first surface of the second aspherical lens faces the second laser diode, and the second surface of the second aspherical lens faces the second cylindrical lens. The first surface of the second aspherical lens is planar, and the second surface of the second aspherical lens is spherical. A beam combining module is used to combine the first collimated beam and the second collimated beam into a mixed collimated beam. The beam combining module includes a color combining prism, and narrow-band reflective films are coated on different surfaces of the color combining prism. A beam shrinking / expanding module is used to adjust the diameter of the mixed collimated beam. The beam combining module includes a front convex lens and a rear concave lens, and the front convex lens and the rear concave lens are coated with anti-reflective films corresponding to the wavelength of the collimated beam, thereby effectively collimating the laser beam.

[0062] Furthermore, by setting the surface profile, numerical aperture, and focal length of the first and second aspherical lenses, as well as the focal lengths of the first and second cylindrical lenses, the laser beam can be collimated more effectively, thereby improving the detection efficiency of the system.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-wavelength laser beam combining and emission system for time-of-flight sensing, characterized in that, include: The first collimation module includes a first laser diode, a first aspherical lens, and a first cylindrical lens. The first laser diode is used to emit a first collimated beam, the first aspherical lens is used for collimation of the fast axis, and the first cylindrical lens is used for collimation of the slow axis. The first surface of the first aspherical lens faces the first laser diode, and the second surface of the first aspherical lens faces the first cylindrical lens. The first surface of the first aspherical lens is planar, and the second surface of the first aspherical lens is spherical. The second collimation module includes a second laser diode, a second aspherical lens, and a second cylindrical lens. The second laser diode is used to emit a second collimated beam, the second aspherical lens is used for collimation of the fast axis, and the second cylindrical lens is used for collimation of the slow axis. The first surface of the second aspherical lens faces the second laser diode, and the second surface of the second aspherical lens faces the second cylindrical lens. The first surface of the second aspherical lens is planar, and the second surface of the second aspherical lens is spherical. A beam combining module is used to combine the first collimated beam and the second collimated beam into a mixed collimated beam. The beam combining module includes a color combining prism, and narrow-band reflective films are coated on different surfaces of the color combining prism. A beam-shrinking / beam-expanding module is used to adjust the diameter of the mixed collimated beam. The beam-combining module includes a front convex lens and a rear concave lens, and the front convex lens and the rear concave lens are coated with anti-reflection films corresponding to the wavelength of the collimated beam. The surface profile sag of the first and second aspherical lenses is calculated using the following formula: Where z is the surface elevation at the corresponding position, r is the radial coordinate, c is the curvature of the surface, A is the aspherical coefficient, and i is a natural number; When the wavelengths of the first collimated beam and the second collimated beam are different, the two prism surfaces facing each other of the color combining prism are coated with narrow-band reflective films of corresponding different wavelengths. When the wavelengths of the first collimated beam and the second collimated beam are the same, the two orthogonal surfaces inside the color combining prism are coated with dichroic films of corresponding wavelengths.

2. The multi-wavelength laser beam combining and emission system for time-of-flight sensing according to claim 1, characterized in that, The numerical aperture (NA) of the first aspherical lens and the second aspherical lens is greater than 0.

5.

3. The multi-wavelength laser beam combining and emission system for time-of-flight sensing according to claim 2, characterized in that, The focal lengths of the first and second aspherical lenses are calculated using the following formula: Where f is the focal length of the aspherical lens, D is the diameter of the target beam, and NA is the numerical aperture.

4. The multi-wavelength laser beam combining and emission system for time-of-flight sensing according to claim 1, characterized in that, The focal lengths of the first cylindrical lens and the second cylindrical lens are calculated using the following formula: Where f′ is the focal length of the cylindrical lens, D is the diameter of the target beam, and θ0 is the emission angle in the slow axis direction.

5. The multi-wavelength laser beam combining system for time-of-flight sensing according to claim 1, characterized in that, The color-combining prism uses ultraviolet fused silica as its substrate.

6. The multi-wavelength laser beam combining system for time-of-flight sensing according to claim 1, characterized in that, The front convex lens and the rear concave lens use ultraviolet fused silica as the substrate.

7. The multi-wavelength laser beam combining system for time-of-flight sensing according to claim 1, characterized in that, The narrowband reflective film has a reflective bandwidth of ±10nm from the center wavelength.

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