CN201156109Y - Apparatus for breaking laser coherence - Google Patents

Abstract

The utility model relates to a device used to destroy the laser coherence, which is characterized by simple structure and low cost. The device comprises a reflecting device (13), a firm mounting structure (14) and a fast rotating motor (15). The fast rotating motor is mounted on the firm mounting structure, the reflecting device is mounted on a rotary motor shaft, and the fast rotating motor rotates at a high speed to drive the reflecting device to rotate at a high speed. Consequently, the device can destroy the laser coherence by continuously changing the optical length of a laser beam. The device is mainly applicable to cases in which the laser coherence needs to be destroyed.

Description

A kind of device that is used to destroy laser coherence

Technical field

The present invention relates to a kind of a kind of device that can change laser coherence, more precisely is to utilize scanister to destroy the coherence of laser.

Background technology

It is good that laser has direction, and monochromaticity is good, and the coherence is good, plurality of advantages such as concentration of energy.Since laser occurred, laser technology was applied to industry-by-industry and field widely at present.But is different for different application to the requirement of laser, the application that has is these characteristics of utilizing its concentration of energy, as laser bonding, have plenty of these characteristics of its coherence of utilizing, as various interference instruments, the monochromaticity of utilizing its laser that has, as utilize specific optical maser wavelength to carry out material and detect, have plenty of and utilize its directivity, as laser lighting.Because due difference needs to utilize certain specific character of laser sometimes, but does not wish another characteristic again, utilizes its monochromaticity as need, but does not need its coherence.If this demand is arranged, just need to destroy the coherence of laser.As laser some demands in illumination, owing to can producing interference ring, the interference of laser has a strong impact on image quality, therefore, in the occasion that this class is used, need to destroy the coherence who produces in the illumination.

According to the optics ultimate principle, light wave is relevant should to satisfy following 3 points: frequency is identical, and constant phase difference, optical path difference satisfy half integral multiple of optical wavelength.Therefore the coherence to be destroyed and one that destroys three links must be able to finished.Obviously, for laser, the wavelength of light wave can't change, and the phase differential of light wave also can't change, the optical path difference that also just only changes that can change.

The method that changes optical path difference has a lot, as allows laser export by optical fiber, because light repeatedly reflection in optical fiber just can effectively destroy the coherence, thereby eliminate interference fringe.But adopt this mode, need the optical interface of optical fiber, for LONG WAVE INFRARED laser, as carbon dioxide laser, the cost of optical fiber is very high, and optical fiber attenuation is serious, because the optical fiber of this wave band adopts the silver halide material life-span short more.The optical material of the employing different refractivity that has coincides together, thereby allow laser pass through to change optical path difference through repeatedly reflecting reflection, but this kind mode manufactures and designs also comparatively complicated, can't realize this scheme for carbon dioxide laser because the material of available different refractivity is few simultaneously.In order to destroy the coherence of laser, can also adopt the mode that allows laser radiation arrive diffuse reflector, but there is the uncontrollable requirement that can not satisfy the illumination directivity of light beam shooting angle in this mode.The somebody proposes, and changes the reflection case of irradiation object, makes its surface diffuse reflectance, but this mode is infeasible under many circumstances.Therefore for some technique of laser imaging, as the BAGI technology, the lighting system that technical needs such as laser Active Imaging are sought a kind of high performance-price ratio is very necessary.The present invention proposes a kind of simple in structurely, be easy to realize to satisfy that general illumination uses, destroy the method for laser coherence.

Summary of the invention

In order to solve the needs of illumination, being easy to of the present invention proposes realized, the efficient height, be easy to control, laser coherence breaking plant simple in structure.The ultimate principle that the present invention adopts is the method realization by the optical path difference that changes laser.Implementation of the present invention is to utilize the device of high-speed rotation to be reflected into irradiating light beam to realize, variation for the optical path difference that realizes emergent ray, need shine the different position of catoptron at difference moment incident ray, said high-speed rotation can 360 high speed rotating in the degree, also can be the swing rotation in the certain angle, can also be the vibration around kinematic axis.More than these modes can think incident beam is scanned.

According to the principle general introduction of front to invention, the present invention needs, motor that reflection unit can be rotated of a reflection unit.Can learn that according to principle adopting this device to realize inventing not needs controls accurately to rotating speed, get final product and only need have certain high rotating speed, thereby reduce cost, the cost of motor and the complexity of control of control greatly, and reached cost-effective effect.Reflection unit can adopt catoptron, be wedge shape mirror, scanning galvanometer or rotary drum.These reflection units are easy to processing and obtain, and adopt the said device of invention that every requirements such as right alignment of assembling are reduced, thereby have reduced the cost of each side such as artificial.

Description of drawings

Fig. 1, laser coherence breaking plant schematic diagram

Fig. 2, the laser coherence breaking plant is installed schematic diagram

Fig. 3, a kind of wedge reflector that is used for

Fig. 4, a kind of schematic diagram of device that adopts rotary drum scanning

Fig. 5, a kind of schematic diagram of device that adopts vibrating mirror scanning

Specific embodiment

One embodiment of the present of invention as shown in Figure 1, in order to finish a such purpose, allow the normal direction of catoptron with there being a small angle between the rotation axis of catoptron, and the size of angle depends on laser beam divergence.Like this since the shooting angle that the existence of angle will make light in a swing circle in continuous variation, the path of laser can constantly change, light path also can change thereupon, thereby destroys the coherence of laser.The 13rd, plane mirror, 14 motor assembly structures, 15 high-speed electric expreess locomotives, 11 incident raies, 12 emergent raies.High-speed electric expreess locomotive 15 is assembled on the motor assembly structure 14, and catoptron 13 is assembled on the axle of high-speed electric expreess locomotive 15, and incident ray incides on the plane of catoptron.Through outgoing after the flat mirror reflects.As shown in Figure 2, catoptron normal 21 is with having certain included angle between the high-speed electric expreess locomotive turning axle 22.Because catoptron normal 21 is with existing certain included angle between the turning axle 22, normal 21 will carry out high speed rotating around turning axle 22 when rotating like this, and the track of normal will be a circular cone.According to the ultimate principle angle of incidence of light of optics be incident ray with the angle between the catoptron normal, therefore when incident ray is with the turning axle fixed angle, emergent ray also will form cone shape outgoing.So also just caused the variation of light path.Based on as a same reason, said catoptron 13 also can be the wedge shape mirror, as shown in Figure 3.The bottom faces part of wedge shape mirror is perpendicular to high-speed rotating shaft.Because the normal direction of wedge reflector is with existing certain included angle therefore also can reach the effect of destroying the coherence between the turning axle.Wedge shape mirror itself just can guarantee normal with angle small between the Plane of rotation in addition, has reduced the difficulty of assembling.In order to guarantee quality of illumination, the size of angle need be according to the pattern of laser, and the angle of divergence of laser is calculated, hot spot constantly can partially overlap continuously, the coincidence degree of hot spot has determined the output uniformity of light, for the light beam that meets Gaussian distribution and approximate Gaussian distribution, this little angle should be less than or equal to the angle of divergence of laser beam.

As second embodiment of the present invention, as shown in Figure 4, reflection unit adopts rotary drum 43, is similar to usually said rotary drum scanister, the rotary drum high-speed rotation, thus change optical path difference.Laser beam 41 incides rotary drum 43 reflectings surface, is emergent ray 42,44th through reflection back, the axle of motor, and vertical with the normal of rotary drum reflecting surface from the rotating shaft of scheming motor as can be seen, the driven by motor rotary drum carries out high speed rotating.According to the characteristic of rotary drum as can be known,, optical path difference is constantly changed, thereby change the coherence of emergent light in continuous variation for the incident angle of a reflecting surface incident light of rotary drum.The face number of rotary drum and installation need be according to the angles of divergence of laser, and the requirement with a tight waist and lighting device of light beam is calculated to satisfy the demand of illumination.

As the 3rd embodiment of the present invention, as shown in Figure 5, reflection unit adopts level crossing 53, catoptron is around 54 high speed swinging rotations of motor, the normal on mirror reflects plane is perpendicular to rotating shaft, just catoptron 53 normals are made high-frequency low-angle perpendicular to the rotation axis catoptron and are rotatablely moved, and also can be called vibration, and vibration angle depends on the angle of divergence of laser.The incident angle of incident ray 51 will constantly change like this, and the shooting angle of emergent ray 52 also changes thereupon.In order to destroy the coherence preferably, vibration frequency should be high as much as possible, and vibration frequency should not be less than 20Hz, and vibration frequency is high more, and decoherence is good more.Because of purpose is just to destroying the coherence, to the linearity of vibration, repeatability does not have too high requirement.Therefore also reduced requirement to vibrating motor and controller.

High-speed electric expreess locomotive of the present invention can be cost low the brush direct current generator arranged, brshless DC motor, voice coil motor can also adopt the high-speed electric expreess locomotive of other types.The rotating speed of rotary electric machine should be more than per minute 2000 changes, and rotating speed can influence too slowly and destroy the effect of interfering, and the too fast meeting of rotating speed proposes high requirement to motor and structure assembling, changes at per minute 5000 as a preferred embodiment of the present invention motor speed.Vibration if desired, motor should satisfy vibration frequency more than 20 hertz.To the requirement of these motors only be need provide needed rotating speed can and to the velocity accuracy and the no requirement (NR) of its control.

Each embodiment among the present invention all adopts the mode of scanning reflection to destroy the coherence, from the technological level of present Laser Devices, adopts the components and parts of this mode to be easy to processing, and laser is had higher transfer efficiency.As catoptron the reflectivity of carbon dioxide laser is easy to reach 99% level, better can reaches 99.9% level, and the substrate of catoptron can adopt various materials, as glass, pottery, metal material.The substrate skilled worker technology that adopts in this method is simple, can satisfy the laser of dissimilar laser, different spot sizes.

Technology of the present invention can be the part of laser optical system, and its effect mainly is the coherence who destroys laser, if also need to finish other functions then this part must cooperatively interact with other optical elements.As need turning back of light path, then need other optical mirror cooperation can finish functional requirement.

Practice shows, adopts device of the present invention effectively to destroy the coherence, improves the lighting quality of laser image forming apparatus, and with low cost, flexible.

Claims (8)

1, a kind of device that is used to destroy laser coherence comprises reflection unit, high-speed electric expreess locomotive, and incident beam forms emergent ray through reflection unit reflection back, it is characterized in that reflection unit is installed on the high-speed electric expreess locomotive axle, driven by motor reflection unit high-speed rotation.

2, a kind of device that is used to destroy laser coherence according to claim 1, it is characterized in that described reflection unit is a level crossing, the normal direction of level crossing is with existing a little angle between the electric machine rotational axis line, the driven by motor level crossing is around the motor shaft high speed rotating.

3, a kind of device that is used to destroy laser coherence according to claim 1, it is characterized in that described reflection unit is the wedge shape mirror with a little angle, the bottom surface of wedge shape mirror is perpendicular to motor shaft, driven by motor wedge shape mirror high speed rotating, and light beam incides on the inclined-plane of wedge shape mirror.

4, a kind of device that is used to destroy laser coherence according to claim 1 is characterized in that described reflection unit is a rotary drum, and the reflecting surface normal of rotary drum is vertical with motor shaft, driven by motor rotary drum high speed rotating.

5, a kind of device that is used to destroy laser coherence according to claim 1 is characterized in that described reflection unit is the plane galvanometer, and the reflecting surface normal of plane galvanometer is vertical with motor shaft, the high-frequency vibration of driven by motor plane galvanometer.

6,, it is characterized in that more than said motor rotation speed per minute 2000 commentaries on classics according to claim 2,3 or 4 described a kind of devices that are used to destroy laser coherence.

7, a kind of device that is used to destroy laser coherence according to claim 5, the vibration frequency that it is characterized in that the plane galvanometer is more than 20 hertz.

8, according to claim 2 or 3 described a kind of devices that are used to destroy laser coherence, it is characterized in that said little angle is not more than the angle of divergence of laser beam.

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