Device for laser treatment of an object

This invention relates to industrial physics and, in particular, to methods of laser treatment. The laser treatment method consists of irradiation of the surface of an object by laser beams directed to treatment zones having a desired shape, wherein laser beams are subjected to spatial phase modulation dictated by the shape of the treatment zone and the prescribed distribution of intensity and are, simultaneously, rotated. A device realizing this method comprises a source of laser radiation with an optical system for delivery of laser radiation to the object, which is positioned on the optical axis of the source and includes at least one phase computer-designed element made as a reflecting or transmitting plate with a micropattern on the surface thereof, which is dependent on the shape of the treatment zone, distribution of laser radiaiton intensity, and its wavelength (.lambda.), the height (h) of the peaks of the micropattern varying, from the base (a) to the top (b), from 0 to .lambda./2 for the reflecting plate and from 0 to .lambda./(n-1) for the transmitting plate, where n is the refractive index of the transmitting plate.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to industrial physics and, in particular, to laser 
technology and machinery and, more particularly, to a method of laser 
treatment of an object and a device realizing this method. 
2. Description of the Related Art 
At present laser beams are used in many fields of science and technology, 
in industry and medicine to irradiate a specific zone on an object by a 
specific distribution of density of the laser flux in order to achieve an 
energy input for some sort of treatment. This problem is more or less 
effectively dealt with by several known methods of laser treatment using 
many different optical laser systems. But it should be admitted that 
potentialities of laser beams in treatment of various materials are far 
from being fully exploited. Since lasers are not cheap to use, each method 
and device is to be assessed on the basis of efficiency achieved in the 
application of lasers which are the basic component of such methods and 
devices. 
Laser technologies can be classified according to the shape of the 
treatment zone into three types: 
spot laser treatment--piercing blind and through holes, for example, spot 
welding; 
straight line laser treatment--welding, cutting, scribing; 
laser treatment of intricately-shaped patterns--heat treatment, lithography 
or printing, patterning. 
The last and most complicated method of treatment of patterns consists in 
that, first, the optical system produces a laser beam in accordance with 
the required shape and size of the treatment zone (optical image 
production stage), and, second, a specific energy input is applied to this 
treatment zone (transmission of optical image to the object). The shape 
and size of the treatment zone are dictated by specific requirements of a 
production operation. 
Several methods are used to produce an optical image for laser treatment of 
various objects. More popular are a contour-beam method and a mask method 
including contact and projection varieties. 
Known in the art is a contour-beam method of laser treatment of an object 
(V. P. Veiko et al. Lazernaya Obrabotka, 1973, Lenizdat Publ., Leningrad, 
p. 144), wherein an optical image of a pattern is produced within a 
specific exposure period by successively illuminating a specific profile 
or contour by a light beam focused by an objective lens. The assigned 
contour is traced either by moving the object or by scanning the light 
beam. The object is usually placed in the focal plane of the objective 
lens and scanning is performed by mechanical transportation of the optical 
system of the device. It is important in this method that the optical 
system be equipped with at least one lens focusing radiation to a point 
and with a means for relative movement of the laser beam and the object. 
This prior art method has the advantage of efficient use of laser energy. 
It is also good because it can achieve a high density of the energy flux 
in a spot area. But this method is deficient in that it is much less 
efficient in producing intricately shaped patterns because the whole 
treatment zone cannot be exposed at once. Besides, this method provides no 
optical means for producing a specific distribution of laser beam density 
in the treatment zone. These drawbacks restrict the range of production 
operations realizable by this method. If the treatment zone is not an 
outline or contour but a limited surface, this method cannot provide high 
quality of laser treatment. 
Known in the art is a mask laser treatment method (V. P. Veiko et al., 
Lazernaya Obrabotka, 1973, Lenizdat Publ., Leningrad, p. 136), in which a 
laser beam of a specific shape and size is produced by irradiating areas 
on the surface of an object through masks (stencils) installed in the 
optical system of the device realizing this method. Free spaces or slots 
in the mask correspond to the required shape of the treatment zone, while 
the size can be left unaltered, reduced or magnified to a required size by 
the optical system. Two varieties of this method, contact and projection 
methods, have become popular recently. 
The contact method consists in that a mask is pressed against the object 
prior to exposure. The advantage of this method consists in that the 
optical system of the device realizing this method is uncomplicated. But 
this method of laser treatment is deficient in that the object may be 
mechanically damaged when the mask is pressed thereto. On the other hand, 
if the mask is not intimately mated with the surface of the object, the 
quality of laser treatment is affected by diffraction distortions. 
Besides, the mask should be wear-resistant and immune to laser emission as 
compared to the material to be treated. 
In the projection method the mask illuminated by the laser beam features 
slots corresponding to the desired shape of the treatment zone. The 
projection lens is used to demagnify the mask image to a desired size. The 
focal plane of the lens is matched with the surface of the object to be 
treated. There are several optical configurations employed in the 
projection method and, respectively, several different devices realizing 
this method (Lazernaya i Elektronno-Luchevaya Obrabotka Materialov, 
Reference book, N. N. Rykalin et al. 1983, pp. 445-449). This reference 
book also cites parameters of lasers to be used for laser treatment and 
industrial laser installations. 
Mask laser treatment methods, both contact and projection ones, are 
deficient in that a large amount of laser energy is lost on 
non-transparent portions of the mask. Such methods cannot provide a 
desired distribution of laser radiation density over the entire zone of 
treatment. 
Commonly known are combination methods where projection and contour 
techniques are used at the same time. In this case, the projecting optical 
system produces a reduced mask image in the focal plane of the objective 
lens, while scanners produce an optical image of the desired pattern in 
the conventional successive manner. 
Known in the art is a device realizing a projection method of laser 
treatment of objects or materials (Elektronnaya Promyshlennost, Issue 1, 
1976, Moscow, V. Z. Vysotsky et al., Ustanovka s Proektsionnoi Opticheskoi 
Sistemoi dlia Podgonki Resistorov, pp. 22-23) and intended for adjustment 
of parameters of passive components of integrated circuits. This prior art 
device comprises a laser radiation source and an optical system for 
delivery of laser radiation to the object to be treated, which is arranged 
on the optical axis of the laser radiation source. The manufacturing 
process of resistor adjustment consists in removing excess portions of 
resistive film stripes by evaporation of the material to a desired size by 
laser emission. For this purpose, the optical system of the device 
produces a laser beam spot in the desired plane as a 7-10 mm long and 1 mm 
wide straight line, the radiation density being distributed uniformly both 
in length and width. The device is equipped with a laser operating in a 
Q-switched mode at a wavelength of 1.06 micrometers. The output laser beam 
is focused by a positive lens to a cylindrical lens of the optical system, 
which is placed directly before the objective lens. A mask featuring a 
slot of a desired shape is placed behind the cylindrical lens. The 
generator of the cylindrical lens is oriented perpendicular to the slot so 
that the edges thereof are reproduced without distortion by a 
high-resolution objective lens. The plane of line images oriented across 
the slot is located outside the treatment zone and, consequently, the 
distribution of the laser beam density within the slot image is relatively 
uniform, slowly declining from the center towards the edges. The cutting 
length is restricted by the area of uniform energy density distribution by 
means of a special-purpose diaphragm located near the surface being 
treated. 
This device is another striking example of the type of problems encountered 
when conventional optical elements are used to produce a desired shape of 
the treatment zone (a narrow strip, in this case) with a specific 
distribution of laser emission density (uniform, in this case) and maximum 
utilization of the radiated power. The optical system is inevitably 
overcomplicated and requires precision adjustment. Radiated power is 
inevitably lost on the mask. 
Each known method of laser treatment of objects and devices realizing these 
methods have their merits and deficiencies, and their own fields of 
application. But there is no doubt that no existing method of laser 
treatment of specific patterns on objects and no existing device realizing 
this method can provide a combination of two functional capabilities such 
as a specific distribution of density of radiated power and concentration 
of the laser beam power within a treatment zone having a specific shape. 
SUMMARY OF THE INVENTION 
It is an object of this invention to expand the range of production 
operations realized by the proposed method of laser treatment, to improve 
the utilization factor of radiated power, to achieve higher efficiency and 
improve the reliability of the laser treatment process, and to improve the 
quality of laser treatment and its accuracy. 
This object is achieved by a method of laser treatment of an object by 
irradiation of the surface thereof by at least one laser beam directed to 
treatment zones of specific shapes. According to the invention, the laser 
beam is subjected to spacial phase modulation realized in conformity with 
the desired distribution of radiation intensity in a treatment zone and 
accompanied by a simultaneous turn of the optical axis of the laser beam. 
It is advisable that in the method of laser treatment of objects, according 
to the invention, the laser beam which had been subjected to the spacial 
phase modulation should be rotated about its optical axis. 
It is also advisable that in a method of laser treatment of objects, 
wherein the object is treated by at least one beam of invisible laser 
radiation, according to the invention, the invisible laser beam should be 
directed to zones of treatment on the surface of the object by a visible 
laser beam having the same distribution of radiation intensity. 
The object of the invention is also achieved by a device realizing the 
method of laser treatment of objects, comprising a laser radiation source 
and an optical system for delivering laser radiation to the object, which 
is arranged on the optical axis of the laser radiation source. According 
to the invention, said optical system comprises at least one phase element 
of computer optics, ensuring rotation of the laser beam, its spacial phase 
modulation, and redistribution of its power over the treatment zone having 
a desired shape, said computer-designed optical element being made as a 
reflecting or transmitting plate whose surface micropattern is dictated by 
the desired shape of the treatment zone, by the distribution of radiated 
intensity, and by the wavelength of laser radiation, the height of the 
micropattern peaks ranging, from the peak base to its top, from 0 to 
.lambda./2 for a reflecting plate and from 0 to .lambda./(n-1) for a 
transmitting plate, where n is the refractive index of the material of the 
transmitting plate. 
It is admissible that in the proposed device, according to the invention, 
the radiation source should comprise two lasers, one laser generating 
invisible radiation and the other laser generating visible radiation, a 
second optical system being provided on the optical axis of the second 
laser and comprising at least one computer-designed phase element in order 
to produce a visible image of a desired shape, which is optically matched 
with the invisible image in the treatment zone. 
It is advisable that the proposed device, according to the invention, 
should comprise a means for shifting the computer-designed phase element 
in relation to the optical axis of the laser radiation source. 
It is convenient that the proposed device, according to the invention, 
should comprise a set of computer-designed phase elements installed in the 
means for shifting and locking said elements. 
The herein disclosed invention makes it possible to expand the range of 
production operations performed by laser treatment of materials and to 
achieve a higher utilization factor of laser radiation by providing 
flexible control of geometrical characteristics of laser beams in zones of 
treatment on the surface of objects, while retaining radiated power and 
ensuring desired distribution of the laser beam density. This invention 
provides a more reliable laser treatment method characterized by high 
reproducibility when dealing with intricately shaped zones, and higher 
efficiency by cutting down the time for complex production operations. 
Moreover, parameters of production processes can be optimized more easily, 
laser treatment becomes more accurate, the number of optical elements in 
the optical system for delivery of laser radiation to the object to be 
treated is reduced, and the device becomes more reliable and compact. 
The proposed method can be easily combined with other laser treatment 
methods. The range of production operations can be broadened. The process 
of laser treatment of materials can be easily automated, making this 
treatment more reliable and efficient.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The new laser treatment method has been developed with a practical target 
in view--what is the most expedient way to make use of the potentialities 
of existing lasers in order to cope with various technological problems in 
the field of treatment of materials. 
The laser beams are usually round or rectangular in cross-section, while 
the energy input (thermal or thermochemical) is to be applied to an object 
in treatment zones having various intricate shapes and patterns. 
Distribution of radiation intensity over the laser beam cross-section is 
dictated by the laser design, while heat fields having specific 
configurations should be provided in the treatment zone in conformity with 
a particular technology. The laser beam propagates along a straight line, 
while the treatment zone may be situated in a hard-to-get location. Many 
technological problems can be solved if laser radiation with intensity 
distributed in accordance with specific requirements over the treatment 
zone having a specific shape is applied to this zone in a plane required 
for treatment. The object should desirably be placed conviniently in 
relation to the laser radiation source. It is also desirable that the 
dimensions of the optical system used to deliver laser radiation to the 
object of treatment are not too large because of the auxiliary optical 
appliances and elements provided in the system. 
The new laser treatment method is focused to achieve the main target--to 
produce, in the treatment zone, a spot of laser radiation, visible and 
invisible, as a pattern or an area having a specific distribution of 
radiation density or laser power within this spot. The method is to be 
fast, uncomplicated, reliable and economical in terms of low power losses. 
Moreover, the laser beam is to be directed to the treatment zone at a 
specific angle without resorting to additional optical elements installed 
in the system for delivery of laser radiation to the object of treatment. 
This has been achieved by providing a novel, in the field of laser 
treatment, method of producing an optical image of a treatment zone. This 
novel method may be categorized into two variations: static and dynamic. 
The static method of producing an optical image of a treatment zone uses 
spacial modulation of laser beams 1 (FIG. 1), which is dictated by the 
assigned shape of a treatment zone 2 and the assigned distribution I' of 
laser radiation intensity within this zone 2 (PCT/SU 85/00037; CA, A, 
488092). The spacial phase modulation transforms the laser beam having a 
round or rectangular cross-section S and an initial distribution I of 
laser radiation intensity over the beam cross-section so that the size of 
the beam cross-section S is reduced to S' (focusing process) and the shape 
of the cross-section 3 of the laser beam 1 is altered to become the 
assigned shape. Simultaneously, the intensity distribution over the 
cross-section S is redistributed from I to I' and, consequently, the laser 
radiation intensity distribution in a specific period of time is also 
altered. 
The spacial phase modulation of laser beams 1 is effected by 
computer-designed phase elements 3 capable of concurrently turning the 
laser beam 1 which had been propagating along an optical axis 4 to an 
angle .phi. (PCT/SU 85/00037; CA, A, 488092). 
This method permits instantaneous production of an image of the treatment 
zone 2 having a specific shape and a specific radiation intensity 
distribution I' in the focal plane of the computer-designed phase element 
3 at a distance f (FIG. 2) from this element 3. This image may be located 
outside (FIG. 13) or on (FIG. 2) the optical axis 4 of the initial laser 
beam 1. The surface of an object 5 is made to agree with the focal plane 
of the computer-designed phase element 3. Then the object 5 is irradiated 
by the laser beam. The image is transmitted to the object 5 by the process 
of power input of the laser beam 1 to the material of the object 5. 
In some cases, to improve the quality of the image and, consequently, of 
the laser treatment, the laser beam 1 has to be broadened by a telescope 6 
(FIG. 2). The laser beam spread after the telescope 6 is negligible. This 
is particularly important when the laser beam 1 is focused into a narrow 
cylinder arranged along the optical axis 4 thereof, whose length is equal 
to the length "1" of the caustic of the computer-designed phase element 3. 
This method is extremely effective when the treatment zone 2 has dimensions 
comparable with the size of the laser beam 1. When treatment zones 2 are 
especially small, the image produced by the computer-designed phase 
element 3 can be demagnified by a projection lens. 
When dimensions of the treatment zones 2 are significantly larger than the 
size of the laser beam 1, the other, dynamic, variation of the method for 
producing an optical image of the treatment zone 2 should be used. 
The dynamic variation of the method consists in that a complete optical 
image of the treatment zone 2 (FIGS. 4 and 5) is synthesized within the 
exposure period of successive irradiation of the treatment zone 2 having a 
specific shape and size by the laser beam 1 spacially modified, in 
advance, by a computer-designed phase element 3. To this end, the object 5 
and the spacially-modified laser beam 1 should be displaced in relation to 
each other. This is achieved by altering the position in space of either 
the computer-designed phase element 3 (FIGS. 4 and 5) as proposed in this 
invention, or the object 5 of treatment. FIGS. 4 and 5 show variations of 
the method, wherein the computer-designed phase element 3 is transported 
along the optical axis 4 of the laser beam 1 at a velocity V or is rotated 
about its own axis at a speed .omega., respectively. 
This method provides for successive composition of an image of the 
treatment zone 2 having desired shape and size from individual components 
7 of this zone 2, the shape of such components 7 being the basis for 
desiging phase elements 3. This laser treatment method has a much broader 
field of application. The radiation intensity distribution I' can be 
controlled within each individual component 7 of the treatment zone 2, as 
well as the shape of this zone 2, and the speed V of linear travel or the 
speed .omega. of rotation of the computer-designed phase element 3 and/or 
the object can be varied in time V=V(t) and .omega.=.omega.(t). These 
capabilities offer the advantage of performing technological operations 
over a wide surface which are impossible or very complicated to realize by 
any other laser treatment methods. 
The laser treatment method will now be described with reference to a 
simpliest possible device realizing this method. This device is equipped 
with a laser radiation source 8 (FIG. 6) comprising a laser 9, a power 
supply unit 9.sup.I, a beam shutter 10 with an electrical control unit 
10.sup.I, and a laser radiation chopper 11 with a control unit II.sup.I. 
An optical system 12 for delivering laser radiation to the object 5 is 
arranged on the optical axis 4 of the source 8. The optical system 12 
comprises at least one computer-designed phase element 3. In case the 
laser beam is to be spread, the optical system 12 should comprise a 
collimating telescope 6. The object 5 of treatment is placed on a work 
table 13. 
The computer-designed phase element 3 (FIGS. 7 and 8) is a plate reflecting 
or transmitting laser radiation. The microrelief pattern of the plate 
surface is dictated by the shape of the treatment zone 2 (FIG. 6), 
distribution I' of laser radiation intensity within this zone 2, and the 
laser radiation wavelength .lambda.. Each peak 14 (FIG. 7) of the 
micropattern is, in its cross-section, a tooth with one vertical side. The 
other side of the peak 14 is smoothly varying within the height h from the 
base with a width a to the top b. The arrangement of the peaks 14 above 
the surface of the plate with a thickness H is computer-designed in an 
extremely intricate configuration (FIG. 8). The device may be provided 
with computer-designed phase optical elements 3 of two types--reflecting 
and transmitting laser radiation. A reflecting plate is either an 
all-metal plate or a metal plate with a reflective coating applied over 
the micropattern. In both types peaks 14 of the micropattern have the 
height h changing from the base "a" to the top "b" within the range from 0 
to .lambda./2. A transmitting plate is made from a material transparent 
for laser radiation and the peaks 14 of the micropattern have the height h 
ranging from the base "a" to its top "b" within the range from 0 to 
.lambda./(n-1), where n is the index of refraction of the material of the 
plate. The computer-designed optical phase element 3 diverts the laser 
beam 1 to an angle .phi. (FIG. 3) and subjects it to spacial phase 
modulation so that in the treatment zone 2 the cross-section of the beam 1 
has a desired shape and desired distribution of radiation intensity within 
this treatment zone 2. In practical terms, almost all power of the laser 
beam is directed to the treatment zone 2 in this case. 
The device is to perform various technological operations based on thermal 
effect of infrared laser emission, such as piercing of intricately shaped 
holes, piercing of plurality of holes, marking, application of decorative 
patterns on different materials, e.g. acrylic plastic, rubber. 
The device realizing the laser treatment method proposed herein operates as 
follows. 
A computer-designed phase element 3 is placed into an optical system 12 
(FIG. 6). The phase element 3 is a reflecting plate and is adjusted so 
that an image of the treatment zone 2 having a desired shape is produced 
in the working position. The object 5 of treatment (workpiece) is secured 
on the work table 13 in the work position in which the surface of the 
object 5 is made to agree with the surface of the image of the treatment 
zone 2. The chopper 11 is switched on by means of the control unit 
11.sup.I to operate in a desired mode. The control unit 10.sup.I is used 
to open the laser beam shutter 10, and the treatment zone 2 on the surface 
of the object 5 is irradiated for a desired period of time. The device may 
not be equipped with the beam chopper 11. In this case the duration of 
exposure is regulated by the shutter 10 provided with a time relay 
(timer). 
EXAMPLE 1 
The source 8 (FIG. 6) is a CO.sub.2 continuous laser 9 with an output power 
of 100 W, operating on the wavelength .lambda.=10.6 micrometers. Laser 
power and exposure were controlled by the chopper 11 and the 
electromechanical shutter 10. The laser beam 1 had a round cross-section S 
with Gaussian distribution of radiation intensity over this cross-section. 
The laser beam 1 was spread by the telescope 6 and directed to the 
computer-designed phase optical element 3 made as a copper 2 mm thick 
plate with a microrelief pattern provided on its surface as described 
above. The height of micropattern peaks 14 was h.sub.max =.lambda./2=5.3 
micrometers. Individual computer-designed optical elements 3 were selected 
for each operation in particular. 
Some conclusions drawn from the operation of this device are listed below. 
Piercing of multiple holes in non-metallic thin sheets. The best effect is 
achieved by a computer-desingned optical element 3 which transforms the 
laser beam 1 so that it is separated into four portions, each being 
focused into a spot in the treatment zone 2. The holes thus made were 
identical in shape, the distance between holes was extremely precise. In 
this manner, the efficiency of treatment, its quality and accuracy were 
improved. 
Scribing of slots in thin absorbing plates. The best effect was achieved by 
a computer-designed optical phase element 3 which transforms the laser 
beam 1 so that in the treatment zone 2 the laser beam is focused into a 
portion of a straight line, 8 mm long and 0.4 mm thick, with uniform 
distribution I' throughout the length of the line. The plate was split 
along the irradiated line during one exposure. High level of 
reproducibility of this operation practically eliminated spoilage of the 
products. 
Application of ornamental patterns. The computer-designed optical phase 
element 3 focused the laser beam 1 to a spot of a complex shape. This is 
an example of how a complex pattern can be transmitted to the object 5 by 
one pulse without any loss of laser power. Besides, latters and digits 
were applied on products as markings. 
The laser treatment method can also be realized by a device comprising a 
laser radiation source 8 (FIG. 9) and an optical system 12 for delivery of 
laser radiation to the object 5 of treatment, which is arranged on the 
optical axis 4 of the source 8 and comprises at least one 
computer-designed optical phase element 3. The device also comprises a 
control unit 13.sup.I of the work table 13 and a means 15 with a control 
unit 15.sup.I which is to control the position of the phase element 3 in 
relation to the optical axis 4 thereof during exposure. In particular, for 
treatment of large-size workpieces, the work table 13 may be made as a 
two-axis positioning table with mounting attachments, which is used in 
laser NC machines (N. N. Rykalin et al., Lazernaya i Elektronno-Luchevaya 
Obrabotka Materialov, Reference book, 1985, p. 469). 
The means 15 is used to position the computer-designed optical phase 
element 3 which can travel either along the optical axis 4 of the laser 
beam 1 at a velocity V or rotate about its axis at a speed .omega. (FIG. 
9). The means 15 may be a standard detachable head with fixturings and a 
motor to rotate this head during exposure (not shown in the drawing). In 
this case, the weight of movable units is minimized to provide easier 
control of the computer-designed optical phase element 3 and improve the 
accuracy of treatment. 
EXAMPLE 2 
The device of FIG. 9 was used for heat treatment of metal workpieces, 
including hardening, annealing, welding, cutting and the like. The source 
8 was a CO.sub.2 continuous multimode laser with an output power of 0.9 kW 
operating at a wavelength .lambda.=10.6 micrometers. The intensity I was 
non-uniformly distributed over the cross-section S of the laser beam 1 
having a diameter of 45 mm. The optical system 12 for delivering laser 
radiation to the object or workpiece 5 comprises a reflecting 
computer-designed optical phase element 3 made as a copper plate provided 
with a micropattern on the side facing the workpiece 5 and a heat 
exchanger on the opposite side thereof. The phase element 3 can be rotated 
about an axis perpendicular to the plane thereof by a means 15 at a speed 
.omega.=5 rad/min. The workpiece 5 can be transported at a velocity 
V.about.1 mm/min on a coordinate table 13 controlled by a unit 13.sup.I 
provided therefor. 
Let us now deal with an operation of local softening of a workpiece (sheet 
material) by intense heating prior to the further operation of bending. 
The treatment object, a sheet workpiece made of an aluminum alloy, 0.8 mm 
thick. The computer-designed optical phase element 3 has a focal distance 
of f=800 mm and transforms the initial laser beam 1 so that a spot is 
produced on the surface of the workpiece 5 shaped as a narrow rectangle, 8 
by 2 mm, which is used as an individual component 7 of the treatment zone 
2. When the phase element 3 is rotated this spot moves over the surface of 
the workpiece 5 successively covering the entire treatment zone 2 having a 
round shape during the exposure period. In case the treatment zone 2 is a 
long strip, the workpiece 5 is transported so that the zone is exposed to 
the laser beam 1 which had been subjected to spacial phase modulation. In 
this case a strip of the desired length and width is softened on the 
workpiece. 
When the flat workpiece which had been softened by the laser beam was bent, 
an L-shaped section was obtained with dimensions 40.times.60.times.200 mm 
and a radius of curvature of approximately 0.8 mm, increasing to about 3 
mm to the ends of the workpiece. Local softening permits a two- or even 
three-fold reduction of the bending force, higher formability of the 
material, a 50 percent lower labor input due to elimination of finishing 
operations, lesser power consumption due to using low-power fast-speed 
pressing equipment, lower cost of stamping attachments due to elimination 
of adjustment operations, and more accurate bending. 
The laser treatment method can be realized in a plurality of treatment 
zones 2 (FIG. 10). In this case, each zone 2 is irradiated successively by 
laser beams 1. Each treatment zone 2 is irradiated by means of a 
particular spacial phase modulation of the laser beam, effected in 
conformity with the desired distribution I' of laser intensity. The shape 
of the treatment zone 2 may vary. This is achieved by the device realizing 
this embodiment of the proposed method which comprises a set of 
computer-designed optical phase elements 3, each such element being 
secured in a device 16 intended for replacement (transportation) and 
positioning of elements 3. 
Successive change of computer-designed optical phase elements 3 can be 
realized by different embodiments of the device 16, whose alteration and 
fixing is controlled by a unit 16.sup.I. This device 16 may be made as a 
drum or turret head of a conveyer type. The simpliest variant of the 
device 16 is a disk with fixturings, six phase elements 3 being secured in 
the plane of this disk. These computer-designed optical phase elements 3 
are reflecting plates. The disk is set into rotation by a bi-directional 
low-speed motor. When a particular phase element 3 is placed into a work 
position, it is clamped in this position. 
The use of such device 16 ensures higher efficiency of laser treatment by 
cutting down the time for installing and replacing each phase element 3. 
This is particularly true when the laser treatment process is automated. 
The laser treatment method can also be realized by a device comprising a 
laser radiation source 8 (FIG. 11) composed of two lasers 9 and 17 
featuring power supply units 9.sup.I and 17.sup.I respectively. A first 
optical system 12 is placed on the optical axis 4 of the first laser 9 
emitting invisible laser beams 1 intended for power input to the treatment 
object 5. A second optical system 18 is placed on an optical axis 19 of 
the second laser 17 emitting visible radiation. 
The optical (power) system 12 produces, by means of a computer-designed 
optical phase element 3, an invisible image of a treatment zone 2 having a 
desired shape and with a desired distribution I' of laser radiation 
intensity over this zone 2. The guiding optical system 18 produces, by 
means of a computer-designed optical phase element 3 of its own, a visible 
image of the treatment zone, having the same shape and size. These images 
are matched at the stage of preliminary adjustment before the laser 
treatment process is started. The surface of the workpiece 5 is placed in 
the plane of the integrated images, when only the visible low-power 
radiation is available in this plane to visualize the treatment zone 2. 
After that the shutter 10 of the first laser 9 is opened and the treatment 
zone 2 is irradiated. In this manner, invisible laser beams 1 performing 
the treatment are guided to the treatment zones 2 on the surface of the 
workpiece 3 with the aid of visible laser beams having the same intensity 
distribution. 
This method permits precision laser treatment of many varieties of 
workpieces 5, e.g. biological. The laser installation (FIG. 12) described 
below is designed for microsurgery of eyes, particularly for dissection of 
the eye cornea in the shape of a ring, cross, or arc. 
In this case the device is similar to that shown in FIG. 11. Here the 
optical systems 12 and 18 (FIG. 12) comprise telescopes 6 installed at the 
input thereof. Besides, a partially transparent beam splitter plate 20, 
tilting mirrors 21 and 22, and an ophtalmoscope 23 are installed in the 
optical system 18 after the phase element 3 made as a transmitting plate. 
The device of FIG. 12 operates as follows. At first, preliminary adjustment 
of the optical systems 12 and 18 is performed to achieve complete 
agreement of the visible and invisible images of the treatment zone 2 in 
the work position. With the shutter 10 being left closed to intercept the 
invisible beam of the CO.sub.2 laser 9, the workpiece is placed in the 
work position which is visualized by the spacially modulated beam 1 of 
visible laser radiation of the helium-neon laser 17. The accuracy of 
adjustment can be controlled by the physician through the ophtalmoscope 
23. Then the shutter 10 is opened to expose briefly the object 5 which is 
the eye cornea of a patient. A computer-designed optical phase element 3 
producing a cross-shaped spot of the laser beam 1 is used to correct 
myopia, while a phase element 3 producing an arc-shaped spot is used to 
remove a cataract. 
This device can also be used for postoperative(laser therapy whereby 
dissected portions of the eye cornea are exposed to a laser beam 1 of the 
laser 17, which is spatially modulated by a respective optical phase 
element 3 in order to achieve faster healing process. 
Apart from medical applications, the device may be used in industry, 
particularly when the treatment zone 2 is to be visually identified, for 
accuracy sake, by a light spot having a desired shape, e.g. for marking 
products. 
EXAMPLE 3 
One more industrial application of the laser treatment device shown in FIG. 
11 is simultaneous piercing of shaped holes, e.g. square holes or groups 
of holes in ceramic boards for electronic microcircuits, where 
high-quality perforations are required. Multiple perforations in a ceramic 
workpiece 5 have to be made for several reasons: optical break-down of 
gases and evaporated material, hydrodynamic processes in the melt, effects 
of the cavity formed by the laser beam, and many other features of the 
material of the ceramic workpiece 5. The workpiece 5 in this case was a 
ceramic board, 1 mm thick. The zone of treatment was concentrated on the 
vertexes of a square. 
The laser 9 generating invisible radiation was a CO.sub.2 pulsed laser with 
a wavelength of 10.6 micrometers, a pulse duration .tau..about.10.sup.-4 
s, and the energy of each pulse E=2 J. The laser 17 generating visible 
radiation was a ruby laser with a wavelength .lambda.=0.69 micrometers, a 
pulse duration .tau..about.10.sup.-3 s, a pulse energy E=2 J. The optical 
systems 12 and 18 were equipped with computer-designed optical phase 
elements 3 similarly focused to four points arranged in the vertexes of a 
square. At first, the treatment zone 2 was exposed to a pulse of the ruby 
laser 17 with a radiation density of 10.sup.8 J/m.sup.2. This laser 
radiation produced a melt having a uniform depth in the treatment zone 2. 
Then the treatment zone 2 was exposed to a pulse of the CO.sub.2 laser 9 
ensuring evaporation and removal of the melt. In this manner, only two 
pulses were required to perforate four high-precision holes accurately 
spaced apart. 
The device realizing this method of laser treatment can be made automatic. 
In this case, the device (FIG. 13) should comprise a computer 24 to 
control, in accordance with a desired program, the operation of basic 
units and mechanisms of the device. The source 8 comprises a laser 9 with 
a power supply unit 9.sup.I and a shutter 10 equipped with an electrical 
control unit 10.sup.I intended to control the exposure during laser 
treatment. The optical system 12 for delivering laser radiation to the 
workpiece 5 comprises a tilting mirror 21 and a computer-designed optical 
phase element 3 installed in a device 15 with a control unit 15.sup.I. In 
addition, the device also comprises a system 25 for supplying 
technological media to the treatment zone 2, and an observation system 26 
intended for preliminary adjustment of the optical system 12 and 
monitoring the production process. The workpiece 5 is secured on a movable 
work table 13 equipped with a control unit 13.sup.I to control its 
position. A temperature-sensitive transducer is secured to the workpiece 5 
and connected to an instrument 27. The workpiece 5 can be placed on the 
work table by an operator or by a positioner-robot (not shown). The 
computer 24 is electrically connected to the power supply unit 9.sup.I of 
the laser 9, to the control unit 10.sup.I of the shutter 10, to the 
control unit 15.sup.I of the positioning device 15 of the phase element 3, 
to the positioning unit 13.sup.I of the work table 13, and to the 
manufacturing media supply system 25. In this manner the production 
process of laser treatment can be realized according to a program 
available in the computer 24. 
The operator is to place and secure the workpiece 5 on the work table 13, 
start the device, and monitor the production process with the aid of the 
system 26 and the temperature with the aid of the instrument 27. The 
operator may also activate the system 25 for supply of a manufacturing 
medium, e.g. chemically active or inert gas, in accordance with the 
production process peculiarities. 
EXAMPLE 4 
The object 5 of treatment was a hollow cylinder with a 0.3 mm thick wall 
and an absorbing coating applied on the surface thereof. The treatment 
zone 2 was a straight line segment, not more than 2 mm wide. The laser 9 
was a CO.sub.2 continuous laser with a wavelength .lambda.=10.6 
micrometers and output power of 0.9 kW. The laser beam 1 with a diameter 
of 40 mm had non-uniform distribution of intensity over the cross-section 
thereof. The optical system 12 was equipped with a reflecting 
computer-designed optical phase element 3 made as a 2 mm thick copper 
plate. This optical phase element 3 focused the laser beam to a straight 
line segment with a length of 10 mm. Simultaneously with the activation of 
the source 8, a flow of oxygen-containing gas mixture was supplied at a 
rate of 2 m.sup.3 /min. One exposure to the laser beam 1 with a density of 
10.sup.8 W/m.sup.2 was sufficient to perforate a slot measuring 1 by 10 
mm. Then the workpiece 5 was turned with the work table 13 to a desired 
angle and exposed again. This slot piercing operation was repeated with 
each turn of the workpiece 5 along its circumference. Then the optical 
phase element 3 was shifted to a desired distance and slots were 
perforated along the next belt of the workpiece 5 and so on. 
Slots were perforated in a checker-board order over the entire surface of 
the workpiece 5 so that its mechanical strength and rigidity was not 
affected. This operation was employed to manufacture tubular filters. 
The laser treatment method proposed in this invention and the device 
realizing this method provide a combination of possible applications: 
treatment of the surface of a workpiece 5 in zones 2 having desired 
shapes; producing, in the zone 2, a desired distribution of laser power 
intensity during treatment of the workpiece 5; concentration of the laser 
beam power directed to the treatment zone 2; and delivery of the laser 
beam 1 to the workpiece 5 at a desired angle .phi. in conformity with the 
manufacturing requirements of the process of treatment of the workpiece 5. 
Higher efficiency of laser treatment by the proposed method is achieved by 
employing a multiple-zone treatment process, reducing the length of the 
production process due to elimination of auxiliary operations, and 
utilizing high-speed production equipment. 
The quality of the workpieces 5 has also been improved since it acquires a 
combination of manufacturing and operational properties characterized by 
high specific and fatigue strength and durability after this type of laser 
treatment by the device according to the invention. 
The proposed method of laser treatment of objects and a device realizing 
this method may find extensive use in many fields of industry, for 
example, in metal treatment for local thermal hardening of workpiece 
surfaces, including hardening and doping, and for thermal weakening of 
workpiece surfaces followed by mechanical treatment (for example, bending 
and stamping of intricately shaped workpieces), for piercing group holes, 
welding, cutting of sheet materials, pipes and rods, for marking of 
workpieces made of fragile and high-strength materials. 
This method can also be used for treatment of non-metal materials and 
manufacturing of products from plastic and other polymer materials for 
stamping of intricately shaped workpieces and for finishing of holes to a 
specific shape and in the prescribed arrangement. 
This method can be used in microelectronics and instrument making for 
treatment (cutting) of the surface layer of printed circuit boards and 
other elements of microcircuits to a specific depth and along a prescribed 
contour, for sintering of microoptic elements for fiber optical 
communication lines, for treatment of thin films for integrated circuits, 
for cutting and patterning of ceramic substrates of intricate shapes, for 
marking of products made of silicon, ceramic, and other hard and fragile 
materials, for finishing of groups of holes of specific shapes and 
arrangements. 
In light industry, this method can be used for pattern cutting of leather 
materials, natural wooven fabrics and artificial ones, and, also, for 
manufacturing of punched cards. 
This method can be used for manufacturing construction materials from 
ceramics, tufa, glass, and other hard and fragile materials, for 
treatment, by glass founding, of surfaces in accordance with specific 
patterns, for marking, for finishing of groups of holes of specific shape 
and arrangement. 
In lithography, for manufacturing photographic masks. 
Besides, the herein disclosed method and device can be used in medicine for 
surgical operations, for example, ophthalmological ones, and for 
therapeutical treatment.