CN108169895A - Hard light path light beam flexible transmission positioning method and device - Google Patents

Abstract

The present invention proposes a method and device for flexible transmission and positioning of light beams with a hard optical path. Using the technology of flexible transmission of space beams, laser manufacturing of large-format complex patterns mainly includes: planning the beam space scanning path, performing beam space scanning, and according to the scanning results, The movement of the components in space is controlled by the transmission positioning motion platform, and the position of the spot is accurately positioned; the laser scanning speed is associated with the laser pulse, the faster the scanning speed, the more the number of laser pulses, by controlling the scanning speed and the number of laser pulses Fine manufacturing of large-format complex patterns; the beam is controlled by a four-degree-of-freedom rotating arm in space, and the control process is completed by the movement of the horizontal and vertical rotation axes. During the control process, the synchronization of the horizontal and vertical rotation axes is maintained, and the beam angle is monitored by a CMOS camera. Deviation, angle deviation passes through the reflector, and the beam deflection angle is detected by the beam position detector; the horizontal and vertical rotation axes are fine-tuned according to the deflection angle.

Description

A method and device for flexible transmission and positioning of light beams with a hard optical path

technical field

The invention belongs to the field of advanced laser manufacturing, and relates to a method and device for flexible transmission and positioning of light beams with a hard optical path. For laser fabrication of large format complex patterns.

Background technique

A new type of light source appeared in the 1960s, which has the characteristics of good monochromaticity, good directionality, good coherence, and energy concentration. Femtosecond optical pulses refer to laser pulses with a duration of 10 ^-12 s-10 ^-15 s. This laser pulse has the characteristics of extremely high peak power, wide spectral width and extremely short laser emission time. With its unique ultra-short duration and ultra-strong peak power, the femtosecond laser has created a new field of ultra-fine material, low damage and three-dimensional processing of materials, and its application is becoming more and more extensive. According to the ultra-short and ultra-intensive characteristics of femtosecond laser, the applied research field can be divided into the research of ultra-fast transient phenomena and the research of ultra-intensive phenomena. They are all deepened and developed continuously with the shortening of laser pulse width and the increase of pulse energy. The most direct application of femtosecond pulsed laser is that people use it as a light source to form a variety of time-resolved spectroscopy techniques and pump/probe techniques. Its development directly drives the research of physics, chemistry, biology, materials and information science into the field of microscopic ultrafast processes, and creates some new research fields, such as femtosecond chemistry, quantum control chemistry, semiconductor coherence spectroscopy, etc. The combination of femtosecond pulsed laser light and nanoscopy allows the study of carrier dynamics in semiconductor nanostructures (quantum wires, quantum dots, and nanocrystals). In biology, people are using the differential absorption spectrum and pumping/detection technology provided by femtosecond laser technology to study the energy transfer, energy transfer and charge separation process of the photosynthetic reaction center. Ultrashort pulse laser is also used in the transmission, processing and storage of information.

The successful operation of the first desktop terawatt laser using chirped pulse amplification technology began in 1988. This achievement marked the beginning of femtosecond ultra-intensive and ultra-high-intensity photophysics research in the laboratory. In this field of research, since the effect of the ultrashort laser field is equivalent to or greatly exceeds the bound field of electrons in atoms, the perturbation theory cannot be established, and new theoretical treatments need to be developed. Under the light intensity of 1020W/cm2, the study of simulated astrophysical phenomena can be realized. Thermal electrons (200KeV) generated by ultra-high-intensity lasers of 1019-1021W/cm2. Another important application of femtosecond laser is microfine processing. Usually, according to the laser pulse standard, the laser pulse with a duration of more than 10 picoseconds (equivalent to the heat conduction time) is a long pulse. When it is used to process materials, the surrounding materials will change due to thermal effects, thereby affecting the processing accuracy. The femtosecond laser pulse with a pulse width of only a few quadrillionths of a second has unique material processing characteristics, such as a small or no melting zone in the processing aperture; it can realize a variety of materials, such as metals, semiconductors, and transparent materials. Even micromachining and engraving of biological tissues; the processing area can be smaller than the focal size, breaking through the diffraction limit, etc. Femtosecond lasers are currently being used by some automakers and heavy equipment manufacturers to process better engine fuel injectors. Using an ultrashort-pulse laser, holes a few hundred nanometers wide can be made in metals. At the recent Optical Society of America meeting in Orlando, IBM's Hayter said that IBM has used a femtosecond laser system for photolithography of large-scale integrated circuit chips. Cutting is performed with a femtosecond laser and there is almost no heat transfer. Researchers at Lawrence Livermore National Laboratory in the US have found that this laser beam can safely cut through high explosives. "The femtosecond laser holds promise as a cold-processing tool for dismantling decommissioned rockets, artillery shells and other weapons," said the lab's Rosk.

Femtosecond lasers can be used to cut fragile polymers without altering their important biochemical properties. Biomedical experts have used it as an ultra-precision surgical scalpel for vision correction surgery, which can reduce tissue damage without leaving surgical sequelae, and can even perform precision surgery on individual cells or be used for gene therapy. People are still investigating how femtosecond lasers can be used in dental treatment. Some scientists have discovered that the use of ultrashort pulse laser can remove a small piece of tooth without affecting the surrounding substances. The UMW series ultrafast laser micromachining workbench recently launched by Clark-MXR of the United States represents the most cutting-edge commercial femtosecond laser micromachining system in this field, which includes everything needed for micromachining with ultrashort pulse laser Equipment and accessories that can be used for micromachining any material to produce sub-micron fine structures without damage to surrounding materials, without material spatter, and with extremely precise and highly repeatable results.

An immediate application of femtosecond pulses is time-resolved spectroscopy. Use femtosecond pulses to observe ultrafast processes such as physics, chemistry and biology. Femtosecond pulses can be used as light sources for confocal microscopes to make three-dimensional images of biological samples. Optical coherence tomography (OCT) using femtosecond pulses as a light source can observe three-dimensional images of living cells. At this time, it does not use the time characteristics of femtosecond pulses, but the wide spectral lines of femtosecond light sources , to produce interference similar to white light, the reflection of phonons excited by femtosecond pulses in semiconductors can be used to measure the thickness of semiconductor films in real time, to monitor the growth of semiconductor films, and use femtosecond pulses for microfabrication, and the holes made are smooth There is no glitch, because the femtosecond pulse does not rely on thermal effect to melt and then evaporate, but directly evaporates the material by a strong field. The femtosecond pulse is used as a light source for optical communication, which can increase the existing communication speed by hundreds of times. High-energy The interaction between femtosecond pulsed laser and plasma can generate high-order harmonics and X-rays, which may be used in controlled nuclear fusion. People have also tried to use the terahertz radiation generated by femtosecond pulses to detect the packaging of integrated circuits. quality, and even the fat content of meat products. In conclusion, femtosecond pulses have many applications.

With the further development and improvement of femtosecond pulsed lasers, more application prospects will be opened up. It is worth noting that whenever the research develops to a certain stage, a group of researchers from various countries will separate from the research team to transform the research results into products. Of course, the original laser companies also pay attention to absorbing new research results.

In terms of national science and technology strategy, the US approach is to support several key universities and national laboratories, such as the Ultrafast Optics Center at the University of Michigan, the Strong Field Physics Laboratory at the University of California, San Diego, Lawrence-Livermore laboratory etc. Japan started the so-called "femtosecond technology plan" in 1996 in the form of a large-scale "production (industry) official (government, ie national laboratory) (university)" research project of the Ministry of International Trade and Industry. Well-known large companies, national laboratories and universities in the United States have also attracted Bell Laboratories in the United States to carry out research on femtosecond pulse technology, with the goal of becoming the leader in terabit high-speed communication technology.

In the field of femtosecond laser manufacturing, beam transmission positioning is very important to manufacturing accuracy and quality. The domestic Xi’an Institute of Optics and Mechanics has adopted the space beam flexible transmission technology and developed laser manufacturing technology and equipment for large-format complex patterns. However, manufacturing efficiency and stability Insufficient; Xi'an Jiaotong University has developed ultra-fast laser processing equipment for metal surface micro-texture, but the efficiency and practicability need to be improved; Dalian University of Technology uses laser and micro-cutting combined processing technology, which can only realize the surface pattern manufacturing of small-sized components; 510 Institute Leading the laser manufacturing of domestic spacecraft solid-surface antenna reflectors, but currently can only rely on Russian laser manufacturing equipment (expensive, nearly 10 million) and Xi'an Institute of Optics and Mechanics engineering prototypes, and the processing format, stability, and efficiency cannot meet the requirements; The technology and equipment for the marking of engine turbine parts are completely blank in China.

Contents of the invention

The traditional manufacturing of large-scale component surfaces relies on a five-axis platform to realize component movement, and there are problems such as mechanism interference, large space occupation, and low precision/efficiency. Efficiency, while developing precise beam pointing technology. The beam space high-speed flexible transmission positioning and precise pointing technology solves the problems of large space occupation and low precision/efficiency of laser manufacturing equipment on the surface of large components. It involves a hard optical path beam flexible transmission positioning method and device. Angle: -100°~+100°, beam horizontal swing angle: 0~360°; angle deviation between the horizontal rotation center axis and the vertical rotation center axis: ≤5″, repeat positioning accuracy ≤2μrad; maximum beam transmission scanning speed 1m /s.

The method mainly includes: planning the spatial scanning path of the beam, scanning the beam space, and according to the scanning result, the transmission and positioning motion platform controls the component to move in space, and accurately locates the position of the spot; the laser scanning speed is associated with the laser pulse, and the scanning speed is faster. Faster, the more the number of laser pulses, the fine manufacturing of large-format complex patterns by controlling the scanning speed and the number of laser pulses; the beam is controlled by the four-degree-of-freedom rotating arm in space, and the control process is completed by the movement of the horizontal and vertical rotation axes. During the control process, the synchronization of the horizontal and vertical rotation axes is maintained, and the angle deviation of the beam is monitored by a CMOS camera. The angle deviation passes through the mirror, and the beam deflection angle is detected by the beam position detector; the horizontal and vertical rotation axes are fine-tuned according to the deflection angle. An adjustable reflector is installed on the horizontal and vertical rotation axes, and the adjustable reflector includes a first drive mechanism that drives the reflector to rotate along the horizontal axis, and a second drive mechanism that drives the reflector to rotate along the vertical axis. The first drive mechanism includes a piezoelectric ceramic motor for fine adjustment and a servo motor for coarse adjustment. The transmission positioning motion platform controls the component to move along the XYZ axis, and the translation of the component relative to the beam is realized by moving in the XYZ axis direction; the beam is driven by a four-degree-of-freedom rotating arm to rotate in the horizontal and vertical directions, The rotation in the vertical direction realizes the rotational movement of the component relative to the light beam.

The device mainly includes a beam angle deviation detection system, a beam transmission system, a signal control system, and a rotation axis system; wherein, the rotation axis system includes an adjustable reflector. It also includes three separate systems: beam four-degree-of-freedom space high-speed scanning transmission technology system, space rotation synchronization precision control system and beam pointing detection and correction system. Beam four-degree-of-freedom space high-speed scanning transmission technology system studies the correlation between laser scanning speed and laser pulses to achieve fine manufacturing of complex patterns; the space rotation synchronization precision control system enables beam space four-degree-of-freedom transmission, relying on high-speed movement of horizontal and vertical rotation axes If the synchronization accuracy is low, it will cause the angle deviation of the beam pointing, which will cause a large deviation of the processing position after being amplified by the optical reflection component. Therefore, it is necessary to study the synchronization accuracy control technology of the horizontal and vertical rotation axes. The beam pointing detection and correction system is used to adjust the beam pointing. During the transmission of the laser beam, there will be a certain system deviation, which will significantly affect the laser manufacturing accuracy. Therefore, based on the high-speed and high-precision scanning galvanometer processing head, the real-time detection and correction technology of beam pointing is studied, the dynamic error of beam scanning is corrected, and the accuracy error of beam space transmission and positioning system is compensated.

In order to realize the flexible transmission of the beam space in the hard optical path of the laser and ensure the precise pointing of the beam, firstly, through the research of the full closed-loop control technology of the beam path planning and the beam transmission positioning, the scanning positioning and positioning of the beam space pointing based on the coupling of the horizontal rotation and the vertical rotation of the beam are solved. Synchronous control technology; secondly, through technical research such as weight reduction design, precise assembly and adjustment design, anti-collision interference mechanism design, system calibration and compensation, temperature compensation, etc., overcome cantilever compensation, precise detection, assembly and manufacturing of the verticality of the beam horizontal axis and vertical axis Technology; Finally, based on the high-speed scanning galvanometer processing head, the beam pointing detection and correction system is developed by integrating the accurate control design of the processing position, the conjugate design of the processing position and the system calibration. Through the full closed-loop control of beam space transmission, high-speed scanning processing head and beam pointing detection and correction, the spatial high-speed flexible transmission positioning and precise pointing of the beam are realized. The transmission positioning motion platform controls the component to move along the XYZ axis, and the translation of the component relative to the beam is realized by moving in the direction of the XYZ axis; the beam is driven by a four-degree-of-freedom rotating arm in space to rotate in the horizontal and vertical directions. The rotation in the direction realizes the rotational movement of the component relative to the beam.

Description of drawings

Fig. 1 Schematic diagram of the components of the flexible transmission and positioning method for hard light path light beams.

Figure 2. Step diagram of the beam space flexible transmission positioning and precise pointing system.

Detailed ways

The hard light path beam flexible transmission positioning method adopts the space beam flexible transmission technology to carry out laser manufacturing of large-format complex patterns, mainly including: planning the beam space scanning path, performing beam space scanning, and according to the scanning results, the transmission and positioning motion platform controls the components in the Move in space to accurately locate the position of the spot; associate the laser scanning speed with the laser pulse, the faster the scanning speed, the more the number of laser pulses, and finely manufacture large-format complex patterns by controlling the scanning speed and the number of laser pulses; through The beam is controlled by the four-degree-of-freedom rotating arm in space. The control process is completed by the movement of the horizontal and vertical rotation axes. During the control process, the synchronization of the horizontal and vertical rotation axes is maintained. The angle deviation of the beam is monitored by a CMOS camera, and the angle deviation passes through the mirror. The beam deflection angle is detected by the beam position detector; the horizontal and vertical rotation axes are fine-tuned according to the deflection angle. The transmission positioning motion platform controls the component to move along the XYZ axis, and the translation of the component relative to the beam is realized by moving in the XYZ axis direction; the beam is driven by a four-degree-of-freedom rotating arm to rotate in the horizontal and vertical directions, The rotation in the vertical direction realizes the rotational movement of the component relative to the light beam. An adjustable reflector is installed on the horizontal and vertical rotation axes, and the adjustable reflector includes a first drive mechanism that drives the reflector to rotate along the horizontal axis, and a second drive mechanism that drives the reflector to rotate along the vertical axis. The first driving mechanism includes a piezoelectric ceramic motor for fine adjustment and a servo motor for coarse adjustment, wherein the beam vertical swing angle is -100° to +100°, the beam horizontal swing angle is 0° to 360°, and the horizontal rotation The orthogonal angle deviation between the central axis and the vertical rotation central axis is not greater than 5", and the repeat positioning accuracy is not greater than 2μrad.

The transmission positioning device using the hard optical beam flexible transmission positioning method includes a beam angle deviation detection system, a beam transmission system, a signal control system, and a rotation axis system; wherein the rotation axis system includes an adjustable mirror.

The adjustable mirror is used to reflect the laser beam propagating along the Z-axis direction to propagate along the A-axis. In order to facilitate the adjustment of the reflection direction of the laser beam, a three-point orthogonal method is used to realize the two-dimensional small-angle adjustment of the laser mirror group. The used fine-tuning screw adopts a precision fine thread of 0.25 mm, and the angular resolution required for adjustment can be met by using an inner hexagonal wrench. The disc spring is used to press the laser reflector group to the connecting base of the pendulum shaft. The disc spring has good rigidity, and the pressing force can be adjusted by the locking screw. After the fine-tuning screw is adjusted in place, the laser reflector group can be well maintained. The angle is conducive to the stability of the position and angle in the vibration environment such as transportation, where the X-axis drives the worktable to move longitudinally, the Y-axis drives the laser and the optical transmission system on the gantry beam to move laterally, and the Z-axis drives the Y-axis skateboard to move For lateral movement, the C-axis and A-axis are installed at the lower end of the Z-axis for vertical movement. In addition to adjustable mirrors, rotary axis systems also have the option of fixed mirrors.

The structural design basis of the fixed mirror: According to the technical requirements of optical design, the mirror needs to be fine-tuned two-dimensionally along the X and Y horizontal planes. Structural design scheme of the fixed mirror: waist-shaped holes are designed on the base, which can be adjusted along the X-axis; adjustable fixing blocks are designed at both ends of the connecting plate, which can be finely adjusted along the Y-axis by the top wire. The fixed mirror structure is a relatively mature structural design, which has been tested by multiple systems. The overall structural design meets the requirements of the optical design and can meet the design requirements.

The light beam path is switched by the light path switching mechanism. The design basis of the optical path switching structure: According to the technical requirements of optical design, the spectroscopic mirror group needs to play the role of switching the optical path at two positions. Structural design scheme of optical path switching: the spectroscopic mirror group is driven by the cylinder to switch between point-to-point positions; there is a gap between the threaded light hole on the bottom plate and the threaded hole on the marble, which can be fine-tuned around the Z-axis, and the buffer on the positioning block can be adjusted along the incident Fine-tuning of light direction. The overall point-to-point positioning structure is adopted, the guidance is guided by the linear guide rail, the positioning block is a fixed structure, and the buffer can be regarded as a fixed structure when compressed to the end. Since the moving direction of the mirror is reversed along the mirror surface, the direction of the cylinder pushing has no effect on the reflection angle. , The linear guide rail adopts Shangyin MGNR9R60PM, which is a precision-grade guide rail, and the gap between the slider and the guide rail is 2μm after preloading.

The fine-tuning of the rotation of the prism in the Z-axis direction is through the wave plate adjustment mechanism, and the design basis of the wave plate adjustment structure: According to the technical requirements of optical design, the prism needs to be rotated and fine-tuned along the Z-axis, and the wave plate can be rotated. The design basis of the wave plate adjustment structure: There is a gap between the light hole on the prism connector and the thread on the marble mounting plate, which can be adjusted by micro-rotation along the Z axis. The wave plate is fixed on the wave plate rotating frame, rotated to a suitable position, and fixed with fastening screws.

Since the rotating arm needs to rotate, the circuit wires are arranged in the A-axis and C-axis of the rotating arm. Clockwise around the center of the hose circle.

For those skilled in the art, the above-mentioned embodiments are only preferred embodiments of the present invention, and should not be understood as limiting the patent scope of the present invention. Under the premise of not departing from the concept of the present invention, some improvements and substitutions made belong to this invention. protection scope of the invention.

Claims (5)

1. A positioning method for flexible transmission of light beams with a hard optical path, which adopts the technology of flexible transmission of light beams in space to perform laser manufacturing of large-format complex patterns, mainly including: Plan the beam space scanning path, scan the beam space, and according to the scanning results, the transmission and positioning motion platform controls the movement of the components in space, and accurately locates the position of the spot; The laser scanning speed is associated with the laser pulse. The faster the scanning speed, the more the number of laser pulses. By controlling the scanning speed and the number of laser pulses, the large-format complex patterns are finely manufactured; The beam is controlled by a four-degree-of-freedom rotating arm in space, and the control process is completed by the movement of the horizontal and vertical rotation axes. During the control process, the synchronization of the horizontal and vertical rotation axes is maintained, and the angle deviation of the beam is monitored by a CMOS camera. The angle deviation passes through the mirror. , the beam deflection angle is detected by the beam position detector; Fine-tune the horizontal and vertical rotation axes according to the deflection angle. 2. The transmission and positioning motion platform controls the component to move along the XYZ axis, and the translation of the component relative to the beam is realized through the movement in the XYZ axis direction; the beam is driven by a space four-degree-of-freedom rotating arm to rotate in the horizontal and vertical directions, through The rotation in the horizontal and vertical directions realizes the rotational movement of the component relative to the light beam. 3. The femtosecond laser complex component surface processing and manufacturing method according to claim 1, an adjustable mirror is installed on the horizontal and vertical rotation shafts, and the adjustable mirror includes a first drive for driving the mirror to rotate along the horizontal axis mechanism, and a second drive mechanism that drives the reflector to rotate along a vertical axis. 4. The femtosecond laser complex component surface processing and manufacturing method according to claim 1, the first drive mechanism includes a piezoelectric ceramic motor for fine adjustment, and a servo motor for rough adjustment, wherein the beam vertical swing angle is -100 ° to +100°, the horizontal swing angle of the beam is 0° to 360°, the orthogonal angle deviation between the horizontal rotation center axis and the vertical rotation center axis is not more than 5″, and the repeat positioning accuracy is not more than 2μrad. 5. A transmission and positioning device using the flexible transmission and positioning method of the hard optical path light beam as claimed in claim 1, comprising a beam angle deviation detection system, a beam transmission system, a signal control system, and a rotation axis system; wherein, the rotation axis system includes Adjust the reflector.