CN103529552B - LD laser mixed phase device and methods - Google Patents

Abstract

An LD laser phase-mixing device and method, used for phase-mixing the light emitted by an LD light source and collimated by a first collimating lens, wherein the LD laser phase-mixing device includes: a fixed cylindrical seat; a micro motor installed on the fixed cylindrical seat Above; the orthogonal grating is installed on the micro motor and rotates at a high speed driven by the micro motor; the second collimator lens is installed on the fixed cylindrical seat, and the orthogonal grating is located on the object focal plane of the second collimator lens In this way, the light waves emitted by each point on the light-emitting surface of the LD light source are fully mixed on the image focal plane of the second collimator lens after being diffracted by the orthogonal grating and transformed by the second collimator lens. According to the device of the present invention, the structure is simple, the cost is low, the use is convenient and reliable, and it is especially suitable for the field of high-precision laser ranging. The average effect can basically eliminate the aiming error caused by phase unevenness.

Description

LD laser phase mixing device and method

technical field

The invention relates to an LD (laser diode) laser phase mixing device and method, especially suitable for the occasion of using a semiconductor laser array (LDA) as a light source for high-precision laser pulse distance measurement.

Background technique

Aiming error refers to a ranging error caused by inconsistency in ranging results when measuring at different positions in the spot of the beam emitted by the rangefinder. A point of light does not emit light at the same time, there is a certain time delay between them. Especially in high-precision long-distance pulse laser ranging, since it is necessary to use a semiconductor laser array (LDA) integrating multiple LD emitting units to generate high peak power laser pulses, it is more likely to cause time between each LD emitting unit Delay.

The existing optical fiber phase mixing technology utilizes the mode dispersion characteristic of the optical fiber or utilizes the mode coupling characteristic of the optical fiber. The former uses the modal dispersion characteristics of the multimode fiber to perform phase compensation on the luminous tube, that is, the light wave with a phase lag propagates along a mode with a shorter optical path, and the light wave with a phase advance propagates along a mode with a longer optical path. In this way, the phase tends to be uniform on the exit end face of the optical fiber. The latter uses the mode coupling characteristics of the optical fiber to perform phase mixing on the luminous tube, that is, after the light waves emitted by each point on the luminous surface are transmitted through the optical fiber, they are fully mixed under the mode coupling of the optical fiber, that is, on the output surface of the optical fiber. , including the light waves emitted by each luminous point on the luminous surface. During distance measurement, any beam of light directed at the reflective target contains the light wave information of each point on the light-emitting surface, and the average effect of the photoelectric receiving device basically eliminates the aiming error caused by phase inhomogeneity. This also achieves the purpose of improving the phase uniformity.

However, regardless of the mode dispersion characteristics of the optical fiber or the mode coupling characteristics for phase mixing, it can only slightly improve the phase inhomogeneity of the luminous tube. Poor, especially when LDA is used, the influence of phase inhomogeneity on ranging accuracy cannot be eliminated.

Contents of the invention

In order to overcome the above-mentioned shortcomings in the prior art, the present invention proposes the use of rotating orthogonal grating diffraction and lens conversion technology to fully mix the light waves emitted by each point on the LD light-emitting surface on the image focal plane of the lens.

Specifically, on the one hand, the present invention provides an LD laser phase mixing device, which is used to mix the light emitted by the LD light source and collimated by the first collimating lens. The device includes: a fixed cylindrical seat; a micro motor, Installed on a fixed cylindrical seat; the orthogonal grating is installed on a micro motor and rotates at a high speed driven by the micro motor; the second collimator lens is installed on a fixed cylindrical seat, and the orthogonal grating is located on the second collimator On the object focal plane of the straight lens, so that the light waves emitted by each point on the light emitting surface of the LD light source are fully obtained on the image focal plane of the second collimator lens after being diffracted by the orthogonal grating and transformed by the second collimator lens. mix.

Preferably, the micro motor adopts a hollow shaft motor, the orthogonal grating can be fixed on the end surface of the hollow motor, and the LD laser light wave can pass through the shaft center of the motor to the second collimating lens.

In addition, the LD laser phase mixing device according to the present invention can also include a multimode fiber, one end of the multimode fiber is connected to the fixed cylindrical seat, so that the output laser light coupled with the phase mixing of the orthogonal grating and the second collimator lens enters the transmission over multimode fiber.

In addition, the other end of the multimode optical fiber may be provided with a third collimating lens.

On the other hand, the present invention provides an LD laser phase mixing method, which is used for phase mixing the light emitted by the LD light source and collimated by the first collimating lens. In this method, the light collimated by the first collimating lens The high-speed rotated orthogonal grating is incident on the second collimator lens, wherein the orthogonal grating is located on the object focal plane of the second collimator lens, so that the light waves emitted by each point on the light emitting surface of the LD light source pass through the orthogonal The diffraction of the grating and the transformation of the second collimator lens are fully mixed on the image focal plane of the second collimator lens.

Utilize the device and/or method according to the present invention, when ranging, any beam of light waves directed at the reflecting target contains the light wave information of each point on the light-emitting surface, and the average effect of the photoelectric receiving device is basically eliminated. Pointing errors due to uniformity.

The technical solution according to the present invention has the following advantages and effects:

First of all, the present invention fully mixes the light waves emitted by each point on the LD light-emitting surface on the image focal plane of the lens through rotating orthogonal grating diffraction and lens transformation, so as to eliminate the collimation caused by phase inhomogeneity The purpose of the error can improve the measurement accuracy.

Secondly, in the technical solution of the present invention, the phase mixing effect is obvious, the structure is simple, the cost is low, and the use, maintenance and repair are simple, and it is especially suitable for eliminating the influence of the uneven phase error of the luminous tube in a high-precision laser ranging system.

Description of drawings

Fig. 1 schematically shows the structure of an LD laser phase mixing device according to an embodiment of the present invention;

Fig. 2 is the schematic diagram of the orthogonal grating used in the present invention;

Fig. 3 schematically shows the optical path structure of the LD laser phase mixing device according to the present invention;

Fig. 4 schematically shows the structure of an LD laser phase mixing device according to another embodiment of the present invention.

Detailed ways

As shown in Figure 1, the LD laser phase mixing device according to an embodiment of the present invention includes a micromotor 2, an orthogonal grating 3, a collimating lens L2, and a fixed cylindrical seat 1 for installing the micromotor 2 and the collimating lens L2 . Wherein, the micro motor 2 can be installed on one end of the fixed cylinder base 1 , and the orthogonal grating 3 is installed on the micro motor 2 . The micro motor 2 is preferably a hollow-shaft motor, and the orthogonal grating 3 can be fixed on the end face of the hollow-shaft motor. After passing through the orthogonal grating 3, the LD laser can be shot onto the collimator lens L2 through the axis of the motor. The orthogonal grating 3 can rotate at high speed driven by the micro motor 2, and the orthogonal grating 3 is located on the object focal plane of the collimator lens L2, so that the light waves emitted by each point on the light emitting surface of the LD light source pass through the orthogonal grating 3 After the diffraction of the collimator lens L2 and the conversion of the collimator lens L2, it is fully mixed on the image focal plane of the collimator lens L2, and then emerges from the other end of the fixed cylindrical seat 1.

Fig. 2 schematically shows the orthogonal grating structure used in the LD laser phase mixing device of the present invention, and Fraunhofer diffraction occurs after the LD laser passes through the orthogonal grating.

Next, the optical path structure of the LD laser phase mixing device according to the present invention will be exemplarily described with reference to FIG. 3 . The orthogonal grating 3 is placed on the object focal plane of the collimator lens L2, that is, the distance between the orthogonal grating 3 and the collimator lens L2 is the focal length f of the collimator lens L2. The light emitted by the light source LDA becomes a parallel beam after passing through the collimating lens L1. The parallel beam enters the orthogonal grating 3 and undergoes Fraunhofer diffraction. The diffracted light is focused by the collimating lens L2 and then mixed on the image focal plane. Assuming that the horizontal and vertical lines of the orthogonal grating 3 are used as reference coordinates, at this time, after the transformation of the orthogonal grating 3 and the collimator lens L2, the lateral distribution of the image focal plane of the collimator lens L2 is the longitudinal distribution on the LD light-emitting surface. structure, while the longitudinal distribution on the focal plane of the collimator lens L2 is the information of the lateral structure on the LD light-emitting surface, that is, the light wave emitted by any point on the LD light-emitting surface aligns with the light spot on the focal plane of the collimator lens L2 image Each point contributes; if the hollow shaft motor drives the orthogonal grating 3 to rotate, then the light waves emitted from each point on the LD light emitting surface can be fully mixed on the image focal plane of the collimator lens L2.

Fig. 4 schematically shows the structure of an optical fiber LD laser phase mixing device according to another embodiment of the present invention, which further includes a multimode optical fiber 4 on the basis of the embodiment shown in Fig. 1, one end of which can be connected to the fixed round seat 1 . The output laser light diffracted by the above-mentioned orthogonal grating 3 and phase-mixed by the collimating lens L2 is coupled into the multimode optical fiber 4 for transmission, so as to perform phase mixing on the LD light wave for the second time. The other end of the multimode fiber 4 may be provided with a collimating lens L3. In addition, the use of optical fibers can simplify the mechanical structure design of the optical path, making the mechanical structure design of the optical path flexible and volume reduced.

Claims (9)

1. a kind of LD laser mixed phase device, for LD light sources send out through the first collimation lens（L1）The light of collimation is mixed Phase, which is characterized in that including：Fixed cylinder seat（1）；Micro motor（2）, it is installed on the fixed cylinder seat（1）On；Just Hand over grating（3）, it is installed on the micro motor（2）On, and in the micro motor（2）Driving under high speed rotation；Second Collimation lens（L2）, it is installed on the fixed cylinder seat（1）On, and the orthogonal grating（3）It is saturating positioned at the described second collimation Mirror（L2）Object focal plane on so that the light wave that each point is sent out on the light-emitting surface of the LD light sources pass through the orthogonal optical Grid（3）Diffraction and second collimation lens（L2）Transformation after in second collimation lens（L2）Picture focal plane on To being sufficiently mixed.

2. LD laser mixed phase device according to claim 1, which is characterized in that the micro motor（2）Using hollow shaft Motor, the orthogonal grating（3）It is fixed on the end face of hollow motor, LD laser lights wave energy is enough mapped to described by axle center of motor Second collimation lens（L2）On.

3. LD laser mixed phase device according to claim 1 or 2, which is characterized in that further include multimode fibre（4）, this is more Mode fiber（4）One end be connected to the fixed cylinder seat（1）So that through the orthogonal grating（3）Diffraction and second standard Straight lens（L2）The output laser coupled of mixed phase enters the multimode fibre（4）In be transmitted.

4. LD laser mixed phase device according to claim 3, which is characterized in that the multimode fibre（4）The other end set It is equipped with third collimation lens（L3）.

5. LD laser mixed phase device according to claim 1 or 2, which is characterized in that the LD light sources be integrated with it is multiple The semiconductor laser array of LD transmitter units.

6. a kind of LD laser mixed phase method, for LD light sources send out through the first collimation lens（L1）The light of collimation is mixed Phase, which is characterized in that so that described through the first collimation lens（L1）The light of collimation passes through high-speed rotating orthogonal grating（3）Enter It is mapped to the second collimation lens（L2）On, wherein, the orthogonal grating（3）Positioned at second collimation lens（L2）Object focal plane On, so that the light wave that each point is sent out on the light-emitting surface of the LD light sources passes through the orthogonal grating（3）Diffraction and institute State the second collimation lens（L2）Transformation after in second collimation lens（L2）As being sufficiently mixed on focal plane.

7. LD laser mixed phase method according to claim 6, which is characterized in that so that through the orthogonal grating（3）Diffraction With second collimation lens（L2）The output laser coupled of mixed phase enters multimode fibre（4）In be transmitted.

8. LD laser mixed phase method according to claim 7, which is characterized in that in the multimode fibre（4）Middle transmission Laser is via third collimation lens（L3）It projects.

9. the LD laser mixed phase methods according to any one of claim 6-8, which is characterized in that the LD light sources are integrated The semiconductor laser arrays of multiple LD transmitter units.