Smooth surface is carried out the method and the device of light etching micrometer structure
Technical field
The present invention relates to the processing of hard smooth surface, especially adopt the method for laser ablation at smooth surface formation micron order raster image, and the high-rate laser photoengraving device of realizing this method.
Background technology
Be the industrialization that adapts to the 21 century new and high technology, the needs that satisfy the microcosmic manufacturing, the advanced laser processing technology of research and development high-performance is imperative.As a branch of Laser Processing, Laser Micro-Machining in the past 10 years by extensive concern, as one of unit micro-processing technology in the microelectronics integrated technique, now formed fixed mode and dropped in the large-scale production.The very broadband scope of optical maser wavelength from the far infrared to the X ray is mainly used in microelectronics, micromechanics and micro-optic processing three big fields at present.Because the efficient laser source continues to bring out more, such as having the very appearance of high-peak power and ultrashort pulse Solid State Laser, add numerical control operating platform more accurate, at a high speed, the Laser Micro-Machining size can reach several to the hundreds of microns, the width of laser pulse at femtosecond (fs) between nanosecond (ns).
Along with the development and the maturation of laser micro-machining technology, its application constantly enlarges.In microelectronics processing, laser micro-machining technology is all used in the perforation of semiconductor layer, the shearing of register and circuit reparation, in laser image material application, needs the image of the large format diffraction grating composition of micron and submicrometer structure.In addition, the field that can highlight its advantage also has the manufacturing of precision optical instrument, the medical treatment that writes storage, tissue of biological cells of high density information etc.
At present, in field of laser processing, adopt the diode pumped solid state laser device (DPSSL) of high power density, high light beam quality, as Nd:YAG laser instrument (output wavelength 1060nm morely, repetition pulse frequency 50kHz), Nd:YFL laser instrument (output wavelength 1053nm, repetition pulse frequency 15kHz), this class laser instrument average power all can reach 50W, light beam pulsewidth~20ns, through after the process of frequency multiplication, average power can reach 25W, mainly carries out the processing such as delineation, punching, mark of laser.
Existing laser processing mode is: adopt single beam laser to focus on and form machining beams, its hot spot is many transverse mode structures, (~20kHz) mode adopts the vector quantization mode to form repeated laser pulse on same Working position and processes pulsed operation by high repetition frequency during scanning.
The problem that this processing mode exists is:
(1) in order to obtain the high-energy-density luminous point, main focusing by single beam forms high-energy-density, wavelength 1060nm, 532nm pulse laser are to material (as metal) surface working the time, material is low to the absorptivity of light, thermal effect is very obvious, adding man-hour by coming ablator at part generation high temperature, a large amount of luminous energy are transformed into heat energy, form the meteorite crater effect; Thus, general smallest spot can not be focused into thinner light beam about 30-50 μ m, and machining precision is limited.
(2) in order to obtain the laser output of high-average power, the laser beam of employing is many transverse modes hot spot, the poor (M of optical quality
2<10), the light beam coherent length is extremely short, can not form beam interference, therefore, and multi-mode laser Shu Buneng gets high-quality micron order lines (striped).
(3) in order to obtain darker processing effect, (~20kHz) mode adopts the vector quantization mode during scanning, (luminous point place) forms repeated laser pulse processing on same Working position to adopt high repetitive frequency pulsed work.The general Nd:YAG that adopts, the Nd:YOV4 laser instrument, repetition frequency can reach 50kHz, and frequency of operation can reach 5kHz~30kHz.This processing mode, material is low to the absorptivity of first pulse laser, but the energy absorption of follow-up pulse is increased, and helps carrying out darker processing.But shortcoming is to form the meteorite crater effect easily.
We know that the making of micron and sub-micron fine structure must be adopted photoetching process usually, carry out photosensitive record as adopting the photoresist (photo-resist) in the production of integrated circuits.On the one hand, after the employing photoetching process, also to shift processing usually, increase the technology cost with modes such as metal molds; On the other hand, on many commercial Application, photoetching process is unaccommodated.If can directly process the micron order grating fringe in the metal surface, will play an important role in many industrial applications, for example, the processing of micron order image metal die.In fact, if can directly form micron-sized structure, be a very significant job on the surface of material.
At above-mentioned background, the inventor considers that the mode that the interfere type optical head is produced the striped luminous point is incorporated in the Laser Micro-Machining, earlier laser beam splitter is become two-beam, make two bundle laser beam that certain included angle (as about 20 degree) be arranged, again two light beams are closed bundle, focus on the surface of rapidoprint, like this, on the rapidoprint surface, intersect light field and form interference fringe, about about 1 micron of fringe period when beam energy surpasses the material damage threshold value, will form the photetching effect of micron order lines (grating) at material surface.
But, when carrying out the photoengraving of micron order grating, run into following difficult point:
1, interferes the generation of luminous point.In order to guarantee that two-beam can form interference effect, need provide the laser beam that satisfies following requirement: single transverse mode (TEM
00), optical quality M
2<1.1, linear polarization (100:1) and need the control bundle pulsed frequency is adjusted the control bundle energy by electric current.The laser beam that is used for Laser Micro-Machining at present can't satisfy above-mentioned requirements.
2, the homogeneity of light intensity in the luminous point.One side TEM
00Mould can improve the interference of light characteristic, and still, single transverse mode light beam is a Gaussian, and central light intensity height, edge light intensity are low, are unfavorable for very much obtaining even photoengraving in luminous point.For the interference fringe in 1 micron cycle, only 0.5 micron of the width of lines adds man-hour, and the etching depth that needs is between the 0.15-0.20 micron, and like this, according to processing request, the light distribution of the interference fringe in the luminous point must be very even.
Thermal effect during 3, owing to Laser Processing, the continuous laser processing mode of multiple-pulse that generally adopts can produce " meteorite crater " effect at present, can't adapt to the requirement of micron order grid photo-etching erosion.
Summary of the invention
The object of the invention provides a kind of method that can carry out the Laser Processing of micron order striped, and being used on the smooth surface of workpiece directly, photetching goes out the micron order raster image.
Another object of the present invention provides a kind of device that carries out photoengraving that adopts said method.
For achieving the above object, the technical solution used in the present invention is: a kind of method of smooth surface being carried out photoengraving, adopt high power laser as light source, laser beam datum is become directional light, behind diaphragm and lens, produce the branch light beams by beam splitting element, converge to material surface again, form even interference fringe light field, the photetching that surpasses the material damage threshold value on the smooth surface material is realized image making, the frequency tripling or the quadruple of the solid-state laser (DPSSL) of the heavy-duty diode pumping of described light source employing ultraviolet light output, described diaphragm is adjustable rectangular aperture, described interference fringe light field is positioned at the rectangle luminous point of material surface, adopt the output of computing machine output TTL signal controlling laser pulse, carry out single pulse processing at same position, the power of control laser instrument, make in the light intensity phase strong point material generating gasification of interference fringe, form striated structure at material surface.
In the technique scheme, for the reflection-type material, the power of control laser instrument makes etching depth h between 0.1-0.25 micron.
For the transmission-type material, the power of control laser instrument makes etching depth h between 0.4-0.6 micron.
A kind of device that smooth surface is carried out photoengraving, comprise the interfere type optical head, motion platform and control system, described interfere type optical head is by light source, beam shaping system and interference system constitute, the laser that light source sends carries out spectral interference by interference system after the shaping of beam shaping system, interfere type optical head and motion platform can be made X, the relative motion of Y bidimensional, described light source is by the Ultra-Violet Laser light source, the collimating mirror group is formed with the power supply of accepting the TTL signal, wherein, the frequency tripling or the quadruple of the solid-state laser of the heavy-duty diode pumping of Ultra-Violet Laser light source employing ultraviolet light output, described beam shaping system comprises adjustable rectangular aperture and lens combination, described interference system comprises beam splitting element, imaging lens group includes the TTL signal generation apparatus in the described control system.
In the technique scheme, described beam splitting element is used for laser is divided into two-beam, and the scheme that can adopt comprises:
Described beam splitting element adopts two groups of right-angle prism gummeds to form, and wherein one side is plated semi-transparent semi-reflecting multilayer dielectric film, adopts two right-angle prisms as the total internal reflection element, forms directional light, through the lens combination imaging, forms interference fringe on the recording materials surface.By adjusting the distance between prism, can realize zero optical path difference.Adjust the distance between prism synchronously, can change the angle of the interference light that forms after the lens focus, reach the purpose that changes luminous point internal interference fringe spacing.The above-mentioned beam splitting element efficiency of light energy utilization is about 80%.
Perhaps, described beam splitting element is made of the phase grating group, and the variation range in grating cycle is 1 micron one 10 microns, substrate is a fused quartz, and the grating flute profile is a rectangular distribution, and the grooved degree of depth is controlled at λ/[2 (n-1)]), the ultraviolet wavelength of λ for using, n is the light refractive index of substrate.A grade light gross energy can reach 81% like this, ± 1.
Adopt the single beam mode different with common Laser Micro-Machining, the present invention adopts the two-beam interference mode, selects for use the frequency tripling of solid-state laser of heavy-duty diode pumping of ultraviolet light output or quadruple as light source, and light beam satisfies the requirement that produces interference effect.
Simultaneously, adopt the mode of only carrying out single pulse processing in same position, laser pulse is by computing machine TTL signal controlling, and when computing machine sent the pulse signal instruction, laser instrument sent pulse laser beam, guaranteed not form twice processing at same position.On the one hand, single pulse processing will reduce the thermal effect of Laser Processing, avoid " meteorite crater " effect.More chief reason is, interference fringe for 1 micron cycle, only 0.5 micron of the width of lines is if adopt multiple-pulse processing in same position, because the vibration of environment far surpasses 0.5 micrometer range, position of interference fringe in any multiple pulses time is unduplicated, therefore, the processing of any repeatedly continuous impulse can not guarantee that interference fringe is constant or aim at, if adding man-hour, the displacement of bright concealed wire bar just equals d/2, then can not form the processing of striped on material fully.Finally will make serious the decline or smoothing of quality of interference fringe.
The dark (〉 0.1mm of common Laser Processing (mark, delineation, the punching) degree of depth).Such working depth can not be carried out the processing of micron order interference fringe, and dark excessively Laser Processing reduces the diffracting effect of micron order striped on the contrary.The actual grade of the etching of the micron order interference fringe that the present invention requires is controlled at about 1/4th of visible wavelength, and promptly between the 0.1-0.25 micron, finished surface should be smooth surface or minute surface.Therefore, the micron order Laser Processing should realize the damage of material surface, the energy density of gating pulse laser again simultaneously, makes the degree of depth of processing meet above-mentioned requirements.
The advantage of monopulse processing mode is that thermal effect is lower, helps the processing of micron order striped.In order to obtain the diffraction efficiency (brightness) of best interference fringe on the material of final production, etching depth h generally should satisfy, the reflection-type material: and h=λ/4 (, λ is for using light wavelength), general h is controlled between the 0.1-0.25 micron; The transmission-type material: h=λ/[2 (n-1)]) (n is the refractive index of material), general h is controlled at about 0.5 micron.Than the degree of depth of common laser processing, the degree of depth of above-mentioned etching is very low.
Among the present invention, adopt the laser shaping light path that constitutes by the beam shaping system, obtain to compare light intensity and interfere luminous point uniformly, help the processing of high-quality micron order striped.
" raster image " is meant the image by the unit optical grating constitution, the synoptic diagram of raster image as shown in Figure 1, and the unit grating of same orientation and empty frequency is arranged in one or more squares, and entire image is combined by a plurality of such squares.When changing the observation place, can observe square frame line generation telescopic variation.
The beam shaping system, usually can form by diaphragm, quartzy object lens, catoptron and quartzy imaging len, wherein quartzy object lens and imaging lens group constitute the 4F system, and the focal length of object lens finally forms the reduced image of diaphragm greater than the focal length of lens combination on surface of the work.
By the light beam integer, the diaphragm shelves fall the part edge light beam, and the beam intensity ratio in the luminous point of surface of the work is more even, help the even photoengraving of micron order interference fringe.
Micron order grating laser photetching system realizes the image etching by the motion of laser interference optics head on platform, and directions X is the interferometric optical head, and the motion of Y direction can be platform or cylinder mode.Also can adopt high-speed vibrating mirror and F-theta mirror, in a useful area, realize the raster image etching, then,, reach the purpose that realizes the large tracts of land photetching by the X-Y two-dimensional motion by beam flying.
To carry out photoengraving on the crome metal surface is example, is described as follows.The characteristics of chromium are: hardness height, wear-resistant, be processed into minute surface easily, and still, the laser damage threshold of chromium is higher, and the energy force density of the laser beam that needs is higher.Consider the energy loss of light path and the adjustment of hot spot, laser beam (as pulse width 20ns or lower) is answered in the energy density of metal material surface〉2J/cm
2, usually, the output of the average power of laser instrument (351nm-355nm)〉3W@1kHz, with the processing effect of bonding subpulse.Simultaneously, the thermal effect of Ultra-Violet Laser wavelength processing is little, helps realizing on the higher material of absorptivity the processing of micron order striped.
1, the energy requirement of laser beam: about 20%, actual reflectance is less than 15% to the reflectivity of crome metal under 355nm in theory, and therefore, directly the thermal effect of photetching processing is very low on Cr.Experiment shows that the energy of laser beam reaches〉during 0.5mJ, pulse width 20ns focuses on 160 microns luminous points, but etching Cr, at this moment, the about 1.95J/cm of energy density on material C d surface
2Consider the energy loss of light path and the adjustment of hot spot, laser beam (as pulse width 20ns or lower) is answered in the energy density of material surface〉2J/cm
2
2, travelling speed and laser pulse width require: for supporting the high-speed light etching: The faster the better for pulse width, the about 20ns of pulse output as DPSSL, during the processing of monopulse photoengraving, with move distance with criterion as striped light stable etching less than 1/8 fringe period, workpiece is to move less than 6m/s speed, and then the diffraction efficiency of photetching interference fringe is not subjected to the influence of mode of motion.Like this, system carries out the pulse exposure with the mode of the lining by line scan operation that do not stop continuously by computing machine output data control signal, and each etching light spot position is not overlapping.The output frequency of gating pulse can be controlled the distance between the photoengraving interference fringe luminous point.
We can judge the process velocity that such scheme can be supported.If the striped orientation of interfering luminous point is perpendicular to direction of motion, laser pulse width is p, the speed of related movement of luminous point and material is v, in theory, luminous point internal interference striped is the bright concealed wire bar that one group of spacing equates, a bright fringes and a dark fringe are formed a fringe period d, if adding man-hour, the displacement of bright concealed wire bar just equals d/2, then can not form the processing of striped on material fully.Usually, the interference fringe displacement should satisfy<requirement in 1/8 cycle, like this, v should for,
v≤d/(8p)
If d=1 μ is m, p=20ns, then v≤6.25m/s.Since in DPSSL, adopted Q modulation switch and TTL interface, by the TTL control signal that computing machine sends, the output of control laser pulse.Like this, system moves continuously, the photetching control mode of monopulse input continuously, the corresponding light pulse of each etching point, the size s of luminous point, pulsed frequency f and systematically travelling speed v mate mutually, not overlapping between the luminous point, promptly satisfied,
f=v/s
In the above described manner, we calculate under different resolution, different travelling speed, the time of the raster image that system's photoengraving is directly write: as spot definition is 80 μ m (image resolution ratios that are equivalent to 317dpi), rotate (girth 610mm * 800mm) for cylinder, velocity of rotation 0.5r/s, the 317dpi optical pulse frequency is 3.8kHz, about 5.6h of photoengraving speed time.For platform motion, consider that the interferometric optical head has constant weight, adopt straightforward motor (linear motor), its travelling speed can be accomplished〉0.25m/s, like this, photoengraving is directly write about 7 hours of the time of 610mm * 800mm area, guarantees that the flirtatious nonoverlapping pulsed frequency of light is 3kHz.Work under said frequencies, the pulse energy of laser does not have obvious decline.
3, mechanical precision requires: the vibration perpendicular to interfering beam will cause the overlapping region of two light beams to descend.Usually, the not lap of permission two single beam points when interfering can not be greater than 30%, like this, as beam splitting element beam splitting angle of cut under 351nm is 20 degree, the 351nm ultraviolet light allows amplitude ± 34 micron of mechanical vibration, and similarly, it is ± 39 microns that 263nm allows the mechanical vibration amplitude.Shorter ultraviolet wavelength more helps the high-speed cruising of back-up system.
For photetching on the small breadth material, can adopt fixedly interferometric optical head scheme, for photetching on the large format material, first of LASER Light Source and interferometric optical are as motion in one dimension (directions X), another dimension platform or cylinder (Y direction).As adopting in the cylinder mode, when cylinder rotated, the interferometric optical head was along the axially-movable of cylinder, if cylinder surface is coated with thin layer (metal level), when the power density of interference fringe is higher than the damage threshold of metal surface, will form micron-sized optical grating construction at cylinder surface.As adopt platform structure, and various flat work pieces place on the platform, and when laser power density was higher than the damage thresholding on workpiece material surface, surface of the work formed optical grating construction.
4, high-energy threshold materials: the laser beam that interference beam splitter that the employing quartz material is made and lens help using bigger average power.
5, the average length of working life of DPSSL〉10,000 hours, have the very high ratio of performance to price.
6, the output of the energy of DPSSL can be adjusted, and the photetching amount is to regulate by the size of electric current, and the pulse width of laser remains unchanged, and helps accurate control etch amount, does not influence the quality of interference fringe and the travelling speed of system simultaneously.The volume of DPSSL light source is less, and system adopts optical head and platform to move separate mode, has reduced the area of motion platform in the overall optical etching system, helps the manufacturing of high-precision motion control platform.
As seen from the above description, but DPSSL photetching system high-speed cruising not only, and realized the making of micron order structure fringe image.The invention provides a kind of better, the method for making of raster image easily, be the major technological breakthrough of laser fine manufacture field.
Because the technique scheme utilization, the present invention compared with prior art has following advantage:
1. the present invention has adopted the solid-state laser of the heavy-duty diode pumping of ultraviolet light output, can guarantee that two-beam forms interference effect, and can pass through TTL signal controlling light beam pulse frequency, and adjust the control bundle energy by electric current, make micron-sized photoengraving become possibility.
2. the present invention particularly is provided with adjustable rectangular aperture by the setting of optical shaping system, makes that the beam intensity ratio in the luminous point is more even, can satisfy the requirement of micron order processing.
3. the present invention has guaranteed only to carry out a photoetching at same position by the control of control system to the TTL signal, thereby has avoided the generation of " meteorite crater " effect.
Description of drawings
Accompanying drawing 1 is the raster image synoptic diagram by the rectangle luminous point etching behind the beam shaping in the embodiment of the invention one.
Accompanying drawing 2 is the structural representation of photetching system in the embodiment of the invention one;
Accompanying drawing 3 is the structural representation of photetching system in the embodiment of the invention two;
Accompanying drawing 4 is the synoptic diagram of the method for operation (dot matrix rainbow grating) of photoengraving system in the embodiment of the invention one, the example two;
Accompanying drawing 5 is the synoptic diagram of the method for operation (light beam effect) of the change striped orientation of photoengraving system in the embodiment of the invention one, the example two;
Accompanying drawing 6 is the structural representation of the embodiment of the invention three intermediate roll formula photoengraving systems;
Accompanying drawing 7 is the structural representation that adopts galvanometer system in the embodiment of the invention seven;
Wherein: the LASER Light Source of [1], band TTL signal Processing; [2], beam-expanding collimation mirror; [3], iris; [4], quartz lens; [5], catoptron; [6], semi-transparent semi-reflecting beam splitter; [7], prism mirror; [8], quartz lens group; [9], high speed turntable; [10], high-speed motion system; [11], recording materials; [12], workbench; [13], the power supply that comprises the control of TTL and power; [14], [15], high-speed motion control system; [16], computing machine and related software; [17], quartz lens; [18], quartzy phase grating; [19], cylinder; [20], high-speed vibrating mirror; [21], F-theta lens.
Embodiment
Below in conjunction with drawings and Examples the present invention is further described:
Embodiment one: shown in accompanying drawing 2, a kind of method for making of raster image, convert image distribution to pulse control signal, according to the orientation of unit grating wherein and frequently empty, carry out interferometric optical head, platform motion, grating high-speed rotation and light pulse input, the continuous exposure on recording materials that makes a circulation line by line simultaneously, platform, optical head, beam splitting element need not to suspend during exposure, until the making of finishing entire image.The method of operation is referring to accompanying drawing 4.
Realize the laser lithography straight-writing system of said method, comprise by DPSSL LASER Light Source 1, beam-expanding collimation mirror 2, iris 3, quartz lens 4 (object lens), catoptron 5 and the quartz lens group 8 of ultraviolet light output and form the 4F system jointly, rectangular aperture is become a reduced image on recording materials 11 surfaces with TTL signaling interface.Because the position of beam splitting element is irrelevant with the shape of final luminous point, so beam splitting element is as far as possible near lens 4, so that the optical beam ratio on semi-transparent semi-reflecting beam splitter 6 is bigger.By 7 reflections of two prisms catoptron,, the directional light after the beam splitting is focused on the recording materials 11 after the beam splitting through imaging lens group 8.
The above-mentioned interfere type optical head that constitutes by LASER Light Source, beam splitting element, imaging system, be assemblied in the high-speed motion system 10 of tangential movement (directions X), recording materials 11 are placed on the workbench 12 (motion of Y direction), also are provided with the power supply 13, kinematic system control system 14,15 and computing machine and the related software 16 that comprise TTL and power control.Described iris can become rectangle with light beam, and described beam splitting element (6,7 constitute) is placed on the high speed turntable 9, and high speed turntable 9 can rotate, described recording materials 11 be placed on the workbench 12 and be positioned at beam splitting after on the focal plane of imaging system;
In the present embodiment, intersecting the big I of luminous point changes between 5-160 microns, the shape that intersects luminous point can be round dot, rectangle, intersecting the light angle can change between 10 ° to 25 °, recording materials 11 are metal or the polymeric materials that ultraviolet light had stronger absorption spectra, and the output energy of adjusting light makes final beam energy density on material be higher than the damage threshold of material.
Embodiment two: shown in accompanying drawing 3, a kind of photetching system that is used to make raster image, comprise by LASER Light Source 1, beam expander and collimating mirror 2, variable rectangular diaphragm 3, beam shaping system 4,5,17 (lens f1, f2 and diaphragm constitute the 4F system of miniature function), divided beam system (comprises the quartzy phase grating 18 of beam splitting element, imaging lens group 8, high speed turntable 9), above-mentioned by light source, the beam shaping system, the interfere type optical head that divided beam system constitutes, be assemblied in the system 10 of tangential movement (directions X) being placed on workbench 12 (motion of Y direction) and comprising TTL and the power supply 13 of power control of recording materials 11, kinematic system control system 14,15 and computing machine 16.
Described light source 1 can be a ultraviolet output pulsed laser light source; Described rectangular aperture can be regulated.Described beam splitter is placed on the turntable, and turntable can rotate the phase grating of selecting different fringe period, thereby changes the interference of light angle; Described recording materials 11 are placed on the workbench 12 and are positioned on the focal plane of interfering beam; Described beam shaping system comprises adjustable rectangular aperture 3, lens 4, catoptron 5 and lens 6, and described beam splitting interference system is focused at the diffraction light of phase grating on the recording materials 11.In the present embodiment, intersect 20-160 microns of spot definitions.
Embodiment three: a kind of method for making of raster image, earlier image is resolved into different subimages by the orientation of interference fringe, respectively each subimage is moved exposure continuously, between the subimage exposure period, beam splitting element in the optical head need not rotation, only carrying out rotating beam splitting element when subimage switches, this production method has been avoided the rotation of wide-angle between continuous operating period, has improved the continuity of photoengraving operation and the fabricating quality of raster image.Referring to accompanying drawing 5.
The photoengraving system of present embodiment, general structure is identical with embodiment one.
Embodiment four: shown in accompanying drawing 6, a kind of photetching system that is used to make raster image, comprise by LASER Light Source 1, beam expander and collimating mirror 2, beam shaping system 3,4,5,17 (lens f1, f2 and iris constitute the 4F system of miniature function), the light path system that is beamed into picture system composition (comprises beam splitting element 18, imaging lens group 8, rotating mechanism 9), above-mentioned by light source, the beam shaping system, the interference capability optical head that the beam splitting imaging system constitutes, be assemblied in the system 10 of tangential movement (directions X) cylinder 19 (motion of Y direction) and comprise TTL and the power supply 12 of power control, kinematic system control system 13 computing machines 14.
Described light source 1 can be a ultraviolet output pulsed laser light source; Described beam splitter 7 is placed on the turntable 9, and turntable 9 can rotate selects different phase gratings, thereby changes the interference of light angle; Described cylinder 19 surfaces are positioned on the focal plane of interference capability optical head; Described beam shaping system comprises diaphragm 3, lens 4, catoptron 5 and lens 6, and described interference capability optical head is focused at diffraction light on cylinder 19 surfaces.In the present embodiment, at the about 10-160 micron of crossing luminous point size.
The photoengraving system of present embodiment, general structure is identical with embodiment two.
Embodiment five: on the basis of embodiment two, iris is reached minimum, beam splitting element rotates to blank space, not beam split of laser beam directly sees through imaging lens group, and the luminous point on the recording materials is focused on about the 1-5 micron, improve the repetition frequency of pulse laser, system can carry out the two-dimensional vector figure directly to be write, and said system becomes the precise laser straight-writing system of single beam, can carry out the photoengraving of precision circuit plate, mask.The photetching system of present embodiment, general structure is identical with embodiment one, and quartz lens f3 adopts shorter focal length (microcobjective of high-NA).
Embodiment six: a kind of photetching method for making of improved raster image, insert high-speed vibrating mirror in the middle of the lens combination 8 in accompanying drawing 3, shown in accompanying drawing 7, the sweep velocity of high-speed vibrating mirror can reach 1-7m/s, scanning by galvanometer, form the grating etching at regional area, after etching is finished a regional area, run to next regional area by platform, the effect of platform mainly is regional area to be formed raster image link together, and like this, reduces greatly for the requirement of the high speed performance of platform, can improve the cost performance of system, reduce the working time of system.If adopt 80 microns interference luminous point, consider the required time of rotation of beam splitting element, the time of the raster image of actual light etching 610mm * 800mm is about 3-12 hour.
In the present embodiment, intersecting the big I of luminous point changes between the 5-160 micron, the shape that intersects luminous point can be round dot, rectangle, and intersecting the light angle can change between 10 ° to 20 °, and material 11 can be metal level or the polymeric material that near ultraviolet is had stronger absorption spectra.