JP2006053116A - Optics system structure for coupling plurality of laser beams - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optics system for coupling a plurality of diodes and laser beams, which can be made more compact and improved in optical axis stability. <P>SOLUTION: The plurality of diodes are coupled by a prism as shown by figure 2, whereby beams are formed and collimated by using one shared lens. Therefore, using the one shared lens makes the optics system compact and its structure difficult to cause an optical axis misalignment to occur therein. Furthermore, when coupling the plurality of diodes and laser beams having different beam characteristics to form one beam, a "lens type prism" is introduced, which has lens faces capable of preliminarily compensating each beam shape as shown by figure 3, thereby forming and collimating respective beams being coupled, in combination with the above shared lens, such that their shapes and divergent angles are identical to each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

Detailed Description of the Invention

Technical field belonging to the invention

  The present invention relates to a technique for outputting a laser beam having multiple wavelengths by combining a plurality of laser diodes and a laser beam.

  Conventionally, in order to obtain a laser having a plurality of wavelength outputs in one beam, there is a technique of combining a plurality of laser diodes or laser beams using a prism or a reflection mirror.

  It is a conventional technique that a beam is first collimated and then combined with a beam diverging type such as a laser diode. In addition, when two or more lasers are combined, the beams are combined in stages, so that the size of the entire system becomes very large.

  In addition, for the convenience of application, multiple lasers to be combined have the same shape and the same divergence angle, so the conventional method requires a collimator lens that shapes each laser beam before combining. is there. When combining a plurality of laser diodes (LDs), a collimator lens system capable of beam shaping for each LD is required.

  As described above, since the conventional method requires a large number of optical components and a long optical path, complicated optical path adjustment is also necessary for a system having a large size. Furthermore, since many optical components and mounts are used, changes over time such as optical axis misalignment of the combined beam are also unstable factors of the system.

Problems to be solved by the invention

  A more compact optical system made by a simpler method, which can combine multiple lasers, or for each laser beam with different beam properties, minimizes the number of required optical components and achieves a higher beam shaping effect. A combined optical system of a plurality of beams that shapes each beam and has a laser beam of each wavelength component included in the combined laser beam having the same shape and the same beam divergence angle is a problem to be solved by this patent.

Means to solve the problem

  In the past, diode lasers (LDs) that have only visible long wavelength red to infrared have recently been extended to emission wavelengths from ultraviolet to visible short wavelength blue with the improvement of manufacturing technology. Also, LD-pumped green lasers can be made as small products as chips. Multi-wavelength miniaturized lasers with various wavelengths from the visible range of ultraviolet, blue and green or red to near infrared are used in a wide range of applications such as biotechnology and genetics, medical diagnosis, and spectroscopic instruments. In recent years, small laser light sources having a plurality of wavelengths from ultraviolet to visible and near infrared have been demanded for these applications.

  In general, a laser diode is a light source having a large beam divergence angle and requires a collimator lens that can shape the beam before combining.

  Two beams with different polarization directions can be combined by a polarizing prism. Two beams having different wavelengths can be combined with a mirror that reflects only a single wavelength. FIG. 1 shows an example of such a two-beam combining optical system.

  The above-described optical system requires precise optical axis adjustment with a prism or mirror for combining the beams, and deviation of the beam coaxiality due to a slight deviation of the optical axis is also an unstable factor of the system.

  In the present invention, as shown in FIG. 2, two laser diodes are first combined by a prism, and collimated to a parallel beam by a common lens. The key point of the optical axis adjustment of this optical system is to match the light emitting points of the diodes LD1 and LD2 with the back fox focus of the shared lens. The diodes LD1 and LD2 passing through the beam combining prism are non-parallel light having a divergence angle of usually 10 degrees or more. Even if the prism is slightly deviated, the beam is collimated by a common lens after that, so that the optical axis is difficult to deviate.

  In such a method of collimating a plurality of laser diodes with a single common lens, the number of necessary optical components can be reduced, the optical path can be shortened, and the beam coupling can be realized with a compact structure in which the optical axis is hardly displaced.

  However, since the laser diodes of each wavelength to be coupled generally have different beam divergence angles, the beam shape and the divergence angle of each diode to be coupled may be different when collimated with one common lens.

  In order to solve this problem, the present invention introduces a “lens-type prism” capable of precorrecting the shape and divergence angle of each laser diode beam before being combined as shown in FIG. The curved surfaces 36 and 37 in FIG. 3 are of a SELFOC lens system, a spherical system, an aspherical lens system, or a cylindrical lens system, and can be designed according to each beam characteristic. By such a “lens-type prism” method, a plurality of beams having different properties can be combined to output a beam having the same shape and the same divergence angle.

  FIG. 3 shows an embodiment of the present invention, which is an optical system that introduces a “lens-type prism” and a common collimator lens. As shown in FIG. 3, a prism 33 with a lens surface preliminarily corrects the shape of the beam in accordance with the beam characteristics of each diode, and in combination with the shared lens 37, shapes the two combined beams to form a collimator. To do.

  FIG. 4 is an effective optical path diagram of the optical system for the 31st laser diode LD1 of FIG. The prism 33 having 35 lens surfaces is actually seen as one lens that can preliminarily correct the beam shape of the LD1. The LD1 beam is shaped and collimated by a combination of the correction lens and the 37 lens.

  FIG. 5 is an effective optical path diagram of the optical system for the 32nd laser diode LD2 based on the same principle as FIG. The LD2 beam is shaped and collimated by a combination of 33 lenses and 35 lenses having 36 lens surfaces.

  In this way, the beams of LD1 and LD2 are shaped by separate collimator lenses and can be designed to have the same shape and the same divergence angle for the two combined.

  Even with three or more laser beams, the beams can be combined by combining the optical system of the same principle, the “lens-type prism”, and a common collimator lens.

  FIG. 6 shows an embodiment in which three laser beams are combined. Reference numeral 41 in FIG. 6 denotes a chip type laser having a green wavelength of 532 nm. Reference numeral 42 denotes a laser diode having a wavelength of 808 nm for excitation, 43 denotes a YVO4 laser crystal having an oscillation wavelength of 1064 nm, and 44 denotes a second harmonic SHG (Second Harmonics Generation) nonlinear optical crystal. 47 and 50 are laser diodes. For these three lasers, 45 “lens-type prisms” are preliminarily shaped and combined with the beam, and the beam is shaped and collimated with the 53 shared lens. In this way, a plurality of laser beams can be combined with a compact optical system.

The invention's effect

  In the present invention, a plurality of laser beams can be combined by combining a “lens-type prism” and a common collimator lens. Introduction of “lens-type prism” and shared collimator lens system minimizes the number of optical components, miniaturizes the system, or collimates multiple beams previously connected by a prism with a shared lens Thus, the optical axis is less likely to be displaced, and the stability of the optical system is improved.

Combined optics of two collimated laser diode beams. Optical system structure diagram combining two laser diode beams with one common collimator lens. The actual block diagram of the coupling optical system of two laser diode beams using a “lens-type prism” with a beam diameter preliminary correction lens surface. FIG. 4 is an effective optical path diagram of the optical system for the # 31 laser diode LD1 in the optical system shown in FIG. 3; FIG. 4 is an effective optical path diagram of the optical system with respect to the 32nd laser diode LD2 in the optical system shown in FIG. 3; An embodiment of a combined optical system of three laser beams having a beam correction function.

Explanation of symbols

(11) A laser diode (LD1) having a wavelength λ1.
(12) A laser diode (LD2) having a wavelength λ2.
(13) Laser beam shaping and collimator lens.
(14) A prism that combines two beams.
(15) Wavelength λ1 beam transmission, wavelength λ2 beam 45 ° total reflection coding surface.
(16) Beam shape after combination.
(21) A laser diode (LD1) having a wavelength λ1.
(22) A laser diode (LD2) having a wavelength λ2.
(23) A prism that combines two beams.
(24) Wavelength λ1 beam transmission, wavelength λ2 beam 45 ° total reflection coding surface.
(25) LD1 and LD2 both beam shaping and collimator shared lens.
(26) Laser beam shape of LD1 wavelength component after coupling.
(27) Laser beam shape of LD2 wavelength component after coupling.
(31) A laser diode (LD1) having a wavelength λ1.
(32) A laser diode (LD2) having a wavelength λ2.
(33) A “lens-type prism” that combines two beams.
(34) Wavelength λ1 beam transmission, wavelength λ2 beam 45 ° total reflection coding surface.
(35) LD1 laser beam shape corrected spherical surface, aspherical surface, or cylindrical curved surface.
(36) LD2 laser beam shape corrected spherical surface, aspherical surface, or cylindrical curved surface.
(37) LD1 and LD2 both beam shaping and collimator shared lens.
(38) Laser beam shape of LD1 wavelength component after coupling.
(39) Laser beam shape of LD2 wavelength component after coupling.
(41) Diode-pumped 532 nm wavelength chip type laser.
(42) A laser diode (LD1) as an excitation light source.
(43) YVO4 laser crystal.
(44) KTP double wave nonlinear optical crystal.
(45) “Lens-type prism” that combines three beams.
(46) A 532 nm laser beam shape-corrected spherical lens surface.
(47) A laser diode (LD2) having a wavelength λ2.
(48) LD2 laser beam shape corrected spherical surface, aspherical surface, or cylindrical surface.
(49) 532 nm wavelength transmission, λ2 wavelength 45 ° total reflection coding surface.
(50) A laser diode (LD3) having a wavelength λ3.
(51) LD3 laser beam shape corrected spherical surface, aspherical surface, or cylindrical curved surface.
(52) 532 nm, λ2 wavelength transmission, λ3 wavelength 45 ° total reflection coding surface.
(53) A common lens for shaping and collimating three combined laser beams.
(54) Laser beam shape after combination.

Claims (2)

Compact optical system structure that combines multiple laser diodes and laser beams using one common beam collimator lens. The combination of a “lens prism” and a common beam collimator lens according to claim 1, wherein when combining a plurality of laser diodes having different beam shapes and divergence angles and laser beams into one beam, the shape of each beam can be corrected in advance. An optical system structure in which each wavelength component included in the combined beam has the same beam shape and the same beam divergence angle.

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