CN202815330U - Laser speckle eliminating device with dodging function - Google Patents

Abstract

The utility model discloses a laser speckle elimination device with uniform light function, which comprises a laser light source, a transmission medium, a vibration module, and the vibration module is fixedly connected with the transmission medium. There is a scatterer in the transmission medium, and the scatterer is It is formed by a material different from the transmission medium with a uniform density distribution in the transmission medium; the vibration module vibrates under the action of the power supply, and then drives the transmission medium and the scatterer to vibrate together, and the input power of the vibration module is adjusted to In this way, the vibration amplitude of the transmission medium and the scatterer is adjusted until the best speckle elimination effect is obtained.

Description

A laser speckle elimination device with uniform light function

technical field

The utility model relates to a laser speckle elimination device with a uniform light function, which belongs to the technical field of laser imaging.

Background technique

Laser has the characteristics of good directionality, high brightness, good monochromaticity, and good coherence. It is these characteristics that make lasers used in various fields. However, due to the particularly good coherence of the laser, speckle noise will be formed during imaging, which affects the imaging quality, and speckle needs to be controlled. In the typical hollow rectangular strong laser beam output by the laser, the intensity distribution of the beam is non-uniform along the direction of the flow field. The inhomogeneity of the light intensity distribution will lead to non-uniform thermal deformation of the numerous reflective mirrors in the laser transmission channel, which will distort the wavefront distribution of the final output beam of the laser system, resulting in a decrease in the quality of the output beam. So it is necessary to homogenize the laser beam. Therefore, it is a problem to make the emitted light beam uniform while eliminating the speckle.

In high-power laser systems and applications, it is hoped that the output laser beam has a large fill factor and a uniform and smooth intensity distribution. In the amplifier, the inhomogeneity of the input beam will lead to nonlinear effects, which will deteriorate the quality of the output beam and even damage the laser working object. In practical applications, it is affected by the system. The light intensity of the beam is not only modulated by the amplitude, but also has a Gaussian distribution and a phase. Distortion, so dodging is required. The so-called laser beam homogenization technology refers to changing the intensity distribution of the incident laser beam to the required intensity distribution, and at the same time adjusting the phase splitting of the beam to control the propagation path.

Figure 1 shows a schematic diagram of laser speckle formation. The concept of laser speckle: when a beam of light is irradiated on a rough surface with diffuse reflection characteristics, some light can always be seen by using the observation screen to receive the light in the reflected light space. Speckle, this is the phenomenon of laser speckle. The reason is that after the electromagnetic wave or particle beam undergoes random scattering by the medium, it will form a scattered field with random distribution. When a signal is summed by a large number of complex components with independent phases, the signal will appear speckle. These components can have random lengths and random directions, or known lengths and random directions in the complex plane. When these components add up, they constitute what is known as a "random walk". The resulting sum may be larger or smaller depending on the relative phases of the components of the summation, in particular whether constructive or destructive interference is dominant. As shown in the figure, when the laser 102 irradiates the rough material surface 101, the two beams interfere at point A in front of the screen after the similar beams are diffusely reflected by the rough surface. If constructive interference occurs, point A appears as a bright spot, and if destructive interference occurs, point A appears as a dark spot. Therefore, when the laser is directly imaged on the object without processing, speckle noise with random distribution will be displayed on the screen.

The patent publication with the publication number CN101425656A adopts the method of rapidly changing the laser cavity length or the optical path experienced by the laser by using piezoelectric effect, electro-optic effect, acousto-optic effect and etalon to make the laser output wavelength change rapidly or produce a jump to reduce the laser speckle effect. The disadvantage of this method is that the structure of the laser itself needs to be changed, and at the same time, the beam inhomogeneity of the laser beam itself has not been improved.

In view of this, it is necessary to provide a device that can eliminate laser speckle and uniform light without changing the structure of the laser itself.

Utility model content

The utility model provides a laser speckle elimination device with a uniform light function aiming at the deficiencies of the prior art. The technical solution is as follows:

A laser speckle elimination device with uniform light function, comprising a laser light source, a transmission medium, a vibration module, the vibration module is fixedly connected to the transmission medium, there is a scatterer in the transmission medium, and the scatterer is made of a different The material of the transmission medium is formed in the transmission medium with a uniform density distribution; the vibration module vibrates under the action of the power supply, and then drives the transmission medium and the scatterer to vibrate together, and the input power of the vibration module is adjusted to adjust The vibration amplitude of the transmission medium and scatterers is obtained until the best speckle reduction effect is obtained.

散射粒子。In the laser speckle elimination device with uniform light function, the transmission medium can be polymethyl methacrylate, and the scatterer can be 0.3wt% polymethyl methacrylate.

Scattering particles.

In the laser speckle elimination device with uniform light function, the vibration frequency of the vibration module is higher than 80 Hz.

Advantages and positive effects:

This method can combine speckle elimination and laser beam homogenization to achieve the advantage of solving two problems at the same time. In the transmission process, because the transmission medium with scatterers is used, the scatterers refer to objects that can make the light soft and have no obvious projection, so the scatterers can make the transmitted laser beam uniform. The vibration scatterer and the transmission medium are meant to destroy the coherence of the laser in transmission, and the strong coherence of the laser is the main cause of speckle. Among them, the vibration adopts the vibration module, and the corresponding voltage is given to the vibration module to make the transmission medium and the scattering body vibrate together. Different voltages have different vibration frequencies, and the effect of eliminating speckle is also different. The voltage can be adjusted conveniently to obtain the imaging image with the best speckle elimination effect. The utility model adopts the above-mentioned technical scheme, and discloses a method that can effectively eliminate speckles and uniform light. At the same time, compared with other speckle elimination methods, this method does not need to change the structure of the laser itself, and the structure is simple. It is also useful in the field of laser imaging. Great advantage.

Description of drawings

Figure 1 is a schematic diagram of the principle of speckle formation by laser;

Fig. 2 is a frame diagram of the utility model;

Fig. 3 is the structural representation of the utility model embodiment;

Explanation of symbols of main components: rough plane 101, laser light source 102, transmission module 201, vibration module 202, imaging object 203, laser beam 301, scatterer 302, transmission medium 303, vibration module 304, power supply 305.

Detailed ways

Below in conjunction with specific embodiment, the utility model is described in detail.

Fig. 2 is a schematic structural diagram of a laser speckle elimination device with uniform light function of the present invention, including a laser light source, a transmission medium, a vibration module, and the vibration module is fixedly connected to the transmission medium.

散射粒子。在传输介质外部加振动模组304，振动模组在电源305作用下振动，进而带动传输介质303及散射体302一起振动，调节振动模块的输入功率以此来调节传输介质303及散射体302的振动幅度，直到获得最佳的散斑消除效果。振动频率一般要求大于人眼的临界闪烁频率，当频率高于80Hz时，相对能幅已经非常接近0，人眼已经基本感觉不到闪烁，因此振动频率要高于80Hz。激光通过具有振动的传输介质传输后投影在成像物体306上。Fig. 3 has shown the internal structure diagram and optical path principle diagram of the present utility model, wherein the laser beam 301 that laser light source sends is transmitted through the transmission medium 303 that has scatterer 302 in it, and scatterer 302 is by the material that is different from transmission medium 303 with uniform The density is distributed in the transmission medium. Generally speaking, the transmission medium 303 can use polymethyl methacrylate, and the scatterer 302 mostly adopts polymethyl methacrylate with a mass fraction of 0.3wt%.

Scattering particles. A vibration module 304 is added outside the transmission medium. The vibration module vibrates under the action of the power supply 305, and then drives the transmission medium 303 and the scatterer 302 to vibrate together. Adjust the input power of the vibration module to adjust the vibration of the transmission medium 303 and the scatterer 302. Vibrate the amplitude until the best speckle reduction effect is obtained. The vibration frequency is generally required to be greater than the critical flicker frequency of the human eye. When the frequency is higher than 80Hz, the relative energy amplitude is very close to 0, and the human eye can hardly feel the flicker, so the vibration frequency should be higher than 80Hz. The laser light is transmitted through the vibrating transmission medium and then projected on the imaging object 306 .

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present utility model.

Claims (1)

1. A laser speckle elimination device with uniform light function, characterized in that it includes a laser light source, a transmission medium, and a vibration module, the vibration module is fixedly connected to the transmission medium, and there is scattering in the transmission medium body; the vibration module is used to vibrate under the action of a power source, driving the transmission medium and the scattering body to vibrate together.

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