CN102519587B - Device for Measuring the Light Intensity Distribution of a Laser Beam - Google Patents

Abstract

The invention relates to a measurement technique for the light intensity of a laser beam, in particular to a simple device for rapidly measuring the light intensity distribution of a laser beam. The invention solves the problems that the existing laser beam light intensity measurement technology cannot quickly measure the transverse light intensity distribution of the laser beam, the measurement is inflexible, and the operation is cumbersome. The simple device for quickly measuring the light intensity distribution of the laser beam includes an electrodynamic loudspeaker, focusing lens, photodetector, BNC connecting wire, integrating circuit, and digital oscilloscope; the electrodynamic loudspeaker includes a pillar, a permanent magnet, a damping material layer, a coil, Black shading plate, top cover, and coil connecting wire; the lower end surface of the permanent magnet is fixed on the upper end surface of the pillar. The invention effectively solves the problems that the existing laser beam light intensity measurement technology cannot quickly measure the transverse light intensity distribution of the laser beam, the measurement is inflexible, and the operation is cumbersome, and is suitable for fast measurement of the cross-sectional light intensity distribution of the laser beam.

Description

Device for Measuring the Light Intensity Distribution of a Laser Beam

technical field

The invention relates to a measurement technique for the light intensity of a laser beam, in particular to a device for measuring the distribution of the light intensity of a laser beam.

Background technique

Since the birth of the laser, as a light source with high brightness, directivity, monochromaticity and coherence, the laser has been widely used in scientific research, measurement, processing, medical treatment, communication and military fields. In these applications, the lateral light intensity distribution of the laser beam (that is, the distribution of the light intensity on the cross section perpendicular to the beam propagation direction) has always been valued as an important technical performance index for evaluating the quality of the laser beam. According to the theory of confocal resonator, the beam generally output by the laser is Gaussian in the cross-section perpendicular to the propagation direction. However, due to the variety of resonant cavities used in actual lasers, the laser beams that can be output by lasers vary widely. In the history of laser development, different professionals have put forward different requirements for the spot quality of Gaussian laser beams according to their different purposes. In order to meet the needs of various aspects, it is necessary to know the light intensity distribution curve of the laser beam on the transverse section.

So far, people have developed many techniques to measure the light intensity distribution of laser beams, such as small hole probe method, CCD method and knife edge method. Among them, the small hole probe method is difficult to achieve the concentricity of the hole and the laser beam in the experiment, so it is difficult to guarantee the accuracy when measuring the beam spot size, and the light intensity distribution curve cannot be obtained directly when measuring the light intensity. Although the CCD method has high precision, it is only suitable for measuring the spot size of low-power beams, has obvious limitations, and cannot quantitatively reflect the change of light intensity. At present, the knife-edge method is widely used to measure the intensity distribution of Gaussian beams. The knife-edge method usually fixes the blade on the optical translation stage, which can cut the beam along the direction perpendicular to the beam propagation direction, but needs to slowly adjust the translation stage to measure the laser power passing through the edge of the knife edge for many times, so the laser cannot be obtained quickly. The light intensity distribution curve of the beam. Based on the above reasons, it is necessary to invent a simple device that can quickly, accurately and flexibly measure the light intensity distribution of the cross-section of the laser beam to solve the problem that the existing laser beam light intensity measurement technology cannot quickly measure the transverse light intensity distribution of the laser beam. The problem of inflexible measurement and cumbersome operation.

Contents of the invention

In order to solve the problems that the existing laser beam light intensity measurement technology cannot quickly measure the laser beam transverse light intensity distribution, the measurement is inflexible, and the operation is cumbersome, a device for measuring the laser beam light intensity distribution is provided.

The present invention is realized by adopting the following technical scheme: the device for measuring the light intensity distribution of the laser beam includes a dynamic loudspeaker, a focusing lens, a photodetector, a BNC connection line, an integrating circuit, and a digital oscilloscope; the dynamic loudspeaker includes a pillar, Permanent magnet, damping material layer, coil, black light-shielding plate, top cover, and coil connection wire; the lower end surface of the permanent magnet is fixed on the upper end surface of the pillar; the damping material layer is fixed on the upper end surface of the permanent magnet; the coil is sleeved on the permanent magnet The middle part; the black shading plate is vertically fixed on the upper end surface of the coil; the top cover is fixed on the upper end surface of the damping material layer; the coil connecting wire is connected to both ends of the coil; the photodetector is located on the rear focus of the focusing lens; the output of the photodetector is through BNC The connection line is connected with the input end of the integrating circuit; the output end of the integrating circuit is connected with the input end of the digital oscilloscope; the black shading plate is located at the front side of the focusing lens.

When working, the laser beam output by the laser is converged into a very thin point beam through the focusing lens, and the point beam is completely collected by the photodetector located at the focal point on the rear side of the focusing lens. The photodetector converts the detected optical signal into an electrical signal, and the electrical signal is connected to the integration circuit through the BNC connection line for integration processing, and the integrated electrical signal is connected to a digital oscilloscope for display. During specific work, a current in a suitable direction is passed to the coil of the electrodynamic speaker. According to Faraday's law of electromagnetic induction, the coil will vibrate rapidly up and down. At the same time, the black light shield is driven by the coil to quickly cut the laser beam upwards. The intensity of the laser beam changes rapidly as the black shutter moves. The laser beam with varying light intensity is collected by a photodetector after being converged by a focusing lens and converted into an electrical signal. The electrical signal output by the photodetector is a fast-changing curve of light intensity at different positions on the beam cross section, and the electrical signal processed by the integrating circuit is a distribution curve of light intensity. Therefore, the device for measuring the light intensity distribution of the laser beam in the present invention realizes fast, accurate and flexible measurement of the light intensity distribution in the cross-section of the laser beam. During the above process, the top cover plays a role in restricting the upward movement of the coil. The damping material layer can reduce the influence of coil vibration on the measurement process, and increase the service efficiency and life of the electrodynamic loudspeaker. Based on the above process, compared with the existing laser beam light intensity measurement technology, the device for measuring the laser beam light intensity distribution according to the present invention can quickly measure the transverse light intensity distribution of the laser beam, and at the same time, its measurement is more flexible and the operation is more efficient. Simple.

Further, it also includes a cavity; the cavity is provided with a through hole facing the front side of the focusing lens; the dynamic speaker, focusing lens, photodetector, BNC connecting line, integrating circuit, and digital oscilloscope are all located in the cavity; The black gobo is located between the through hole and the front side of the focusing lens. When working, the laser beam output by the laser passes through the through hole on the cavity to reach the focusing lens for convergence, and finally is collected and detected by the photodetector located at the focus of the focusing lens.

The invention effectively solves the problems that the existing laser beam light intensity measurement technology cannot quickly measure the transverse light intensity distribution of the laser beam, the measurement is inflexible, and the operation is cumbersome, and is suitable for fast measurement of the cross-sectional light intensity distribution of the laser beam.

Description of drawings

Fig. 1 is a schematic structural view of the present invention.

In the figure: 1-focusing lens, 2-photodetector, 3-BNC connecting wire, 4-integrating circuit, 5-digital oscilloscope, 6-pillar, 7-permanent magnet, 8-damping material layer, 9-coil, 10 -Black shading plate, 11-top cover, 12-coil connecting wire, 13-cavity, 14-through hole.

Detailed ways

A device for measuring the light intensity distribution of a laser beam, including a dynamic speaker, a focusing lens 1, a photodetector 2, a BNC connection line 3, an integrating circuit 4, and a digital oscilloscope 5;

Described electrodynamic loudspeaker comprises pillar 6, permanent magnet 7, damping material layer 8, coil 9, black light-shielding plate 10, top cover 11, and coil connecting wire 12; The lower end surface of permanent magnet 7 is fixed on pillar 6 upper end surface; Damping The material layer 8 is fixed on the upper end surface of the permanent magnet 7; the coil 9 is sleeved in the middle of the permanent magnet 7; the black light-shielding plate 10 is vertically fixed on the upper end surface of the coil 9; the top cover 11 is fixed on the upper end surface of the damping material layer 8; the coil connecting wire 12 is connected to the two ends of the coil 9;

The photodetector 2 is located at the rear focal point of the focusing lens 1; the output terminal of the photodetector 2 is connected to the input terminal of the integrating circuit 4 through the BNC connecting line 3; the output terminal of the integrating circuit 4 is connected to the input terminal of the digital oscilloscope 5; black The shading plate 10 is located on the front side of the focusing lens 1;

Also includes a cavity 13; the cavity 13 is provided with a through hole 14 facing the front side of the focusing lens 1; a dynamic speaker, a focusing lens 1, a photodetector 2, a BNC connecting line 3, an integrating circuit 4, and a digital oscilloscope 5 are located in the cavity 13; the black shading plate 10 is located between the through hole 14 and the front side of the focusing lens 1.

Claims (2)

1. A device for measuring the light intensity distribution of a laser beam, characterized in that: it includes a dynamic speaker, a focusing lens (1), a photodetector (2), a BNC connection line (3), an integrating circuit (4), and a digital oscilloscope(5); The electrodynamic loudspeaker includes a pillar (6), a permanent magnet (7), a damping material layer (8), a coil (9), a black light-shielding plate (10), a top cover (11), and a coil connecting wire (12); The lower end surface of the permanent magnet (7) is fixed on the upper end surface of the pillar (6); the damping material layer (8) is fixed on the upper end surface of the permanent magnet (7); the coil (9) is sleeved in the middle of the permanent magnet (7); black The shading plate (10) is vertically fixed on the upper end surface of the coil (9); the top cover (11) is fixed on the upper end surface of the damping material layer (8); the coil connecting wire (12) is connected to both ends of the coil (9); The photodetector (2) is located at the rear focal point of the focusing lens (1); the output end of the photodetector (2) is connected to the input end of the integrating circuit (4) through a BNC connection line (3); the integrating circuit (4) The output terminal is connected with the input terminal of the digital oscilloscope (5); the black light shielding plate (10) is located on the front side of the focusing lens (1). 2. The device for measuring the light intensity distribution of laser beams according to claim 1, characterized in that: it also includes a cavity (13); the cavity (13) is provided with a lens facing the front side of the focusing lens (1). The through hole (14); the electric speaker, the focusing lens (1), the photodetector (2), the BNC connection line (3), the integrating circuit (4), and the digital oscilloscope (5) are all located in the cavity (13); The black shading plate (10) is located between the through hole (14) and the front side of the focusing lens (1).