METHOD AND APPARATUS FOR FORMING AND IMAGING LASER BEAMS

Abstract: In one respect the invention relates to an optical method, ensuring maximum depth of field, of forming and imaging laser beams onto a scanning surface, comprising the steps of generating laser beams with diverging or converging axes and imaging each of the laser beams by means of an optical system onto a scanning surface in such a way that each of the laser beams provides a predetermined spot size on the scanning surface and the axes of adjacent laser beams intersect the scanning surface with a distance from each other, which corresponds to a predetermined raster spacing on the scanning surface. According to the invention a first crossing place of the axes of the laser beams and waists of the laser beams are formed at an input focal plane or in the vicinity of an input focal plane, of an equivalent lens corresponding to that subsystem of the optical system which forms the image of said crossing place, and the scanning surface is placed at an output focal plane, or in the vicinity of an output focal plane, of said equivalent lens. The invention on the other hand relates to an apparatus for forming and imaging laser beams, where laser beams of diverging or converging axes are provided and imaged onto a scanning surface by an optical system, which comprises an imaging element (14, 27, 34, 44, 53, 63, 71, 82, 93, 102) having its input focal plane at a crossing place of the laser beams or in the vicinity of said crossing place, said imaging element forming real waists of the laser beams onto the scanning surface (4) with a predetermined waists size and with a distance between the axes of the adjacent waists, said distance corresponding to a predetermined raster spacing on the scanning surface (4).

Description: METHOD AND APPARATUS FOR FORMING AND IMAGING LASER BEAMS Technical field This Invention relates to . method and appara¬ tus for forming and imaging laser beams, wherein spots of predetermined size of ε number of laser beams are formed on a specified scanning surface, the adjacent spots being in a predetermine:! distance from each other. Sackrround art In laser-based information input equipments, 9. g. in object contour scanners, in text-, drawing- or image digitizers and in laser-based output c ipments, e. g. in text-, drawing-, image visuclizator (display) and recording equipments - in addition to the intansity modulation and deflection of t o lrsar ar.ms - there is z need to form a spot of each laser beam on a scanning sur¬ face, where e. g. an image to be digitized or a display s or a light sensitive recording material is placed. Several type of multiple-beam systems are known in which the spot size produced by the intersection of the scanning surface and the individual laser beams, and simultaneously thθ spacing between the centre of any pair of adjacent spots (the raster spacing) can be adjust ed on a specified scanning surface. So the ratio of spot size/spot overlapping can be adjusted, as well. Such a known arrangement is shown in Fig. 1 , where the method is demonstrated with three laser beams. The axes of the laser beams diverging from a common vertex point T (or at least from a small volume) intersect one another in point K (or at least in a small volume around K) lying after lens 1 , i. e. th9 image of the vertex comes into being at point K. If t ≠ 2f, or t / 0 and so t / k, where f is the focal length,t is the object distance and k is the image distance, then lens 1 produces an angular mag- πification. The laser beam waist being at location 2, the distance of which from lens 1 is d_., is imaged by lens 1 to location 3 being at a distance d„ from it, where distan d_ j and distance d~ are measured from the principal planes H- j and !-! 2 , respectively. Generally speaking d ≠ k even if d_ j = t. The laser beam waist is defined as the location of the narrowest b cross-section. The waist size w is defined as the radius of the waist cross-section. In th3 case of Gauss-beams, according to a generally accepted convantion, the spot radius is defined as a distance from the axis of the Gauss-beam, where the intensity of light 2 foils to a fraction 1/e (13.5 ~ j ) of the maximum intensity in the given cross-section. At o given wavelength , the angle of divergence of a lcsar eam is also determined by the waist radius: 8* = -. _ , wh ars θ is the h r- lf of the f ar- f ield dive rgence coπs- £• • — _— * . a Gy a proper choice of system parameters both the spot size and and spacing of adjacent beam axes can be adjusted on the scanning surface, the latter being a plane in the crse of Fig. 1. Parameters of the system: foc l length f, input dat * ?nc * output date. Input data: input waist size w- , input waist distance d , vertex objec distance d , angle {? (1) between axes of adjacent input beams. Output data: output waist size , output waist distance d 2 , vertex image distance k, angle $? (2) between axes of adjacent output beams, distance z of scanning surface 4 from the back principal plain of lens 1 , raster spacing r, what is the spacing of adjacent spot centres created on the scanning surface 4. The first drawback of the aforementioned solution is the shortness of depth of field of the spots, partly because the waist is not coincidental with the scanning surface, partly because the output waist size is bound to be choosen smaller than the required spot size, so the angle of beam divergence increases. Another drawback is the shortness of depth of field of the raster spacing, because of the steep output angle 0 (2) between adjacent beam axes. Disclosure of the Invention The object of the present invention is to provide a method and apparatus for forming laser spots of pre¬ determined size and predetermined raster spacings with maximum depth of field for both the spots and the spacings. In one respect the present invention is a method according to which in a multi-beam image forming system a first crossing place of the axes of the laser beams and waists of the laser beams are formed at an input focal plane or in the vicinity of an input focal plane, of an equivalent lens corresponding to that subsystem of the optical system which forms the image of said crossing place, and the scanning surface is placed at an output focal plane, or in the vicinity of an output focal plane, of said equivalent lens. The input focal plane is located, in the case of a converging equivalent lens in front of, in the case of a diverging equivalent lens behind the first principal plane of the lens at the distance of the focal length. If the optical system is made up of an afocal first subsystem and a subsequent, non-afocal second subsystem, then the equivalent lens corresponds to the^acond subsystem,only. In this case the first crossing place of axes of the laser beams after the afocal system is regarded as the first crossing place for the equivalent lens, and the beam waists are formed in this place by the afocal system. According to the invention, the image of the vertex is formed in a great distance, preferably in in¬ finity, so we can increase the parallelism of the beam axes, e, g, the depth of field of raster spacing. Preferab the laser beams entering the optical subsystem correspond¬ ing to the equivalent lens are formed so, that the angle between the adjacent axes of the laser beams multiplied by the focal length of the equivalent lens gives at least approximately the raster spacing. This is also true for th last imaging element: we have to adjust the angles between axes of adjacent beams entering the last imaging element So suchivalue, that this angle multiplied by the focal length of the said last imaging element gives the raster spacing. In a given case it can be practical to set this (these) angle(s) of axes by the use of an intermediate angle-reducing element. According to a further preferred embodiment of the present invention, the waist radius of the laser beams entering the optical subsystem corresponding to the equi- valeπt lens is to be adjusted to such a value, that the beam divergence half angle, determined by said waist radiu multiplied by the focal length of the equivalent lens should give at least approximately the spot radius pre¬ determined on the scanning surface. So on the one hand the waist size is higher than in the prior art solution recited previously and by this the far-field divergence angle of the output laser beam can be reduced to a minimum i. e, the depth of field for a given output spot size can be increased to a maximum, on the other hand at the place - 5 - of the output waist and in its immediate vicinity the divergence angle of the output laser beam is minimal, this is the reason of having a maximum depth of field for a given spot size. In the case of the present invention the follow¬ ing considerations are valid for the depth of field of raster spacing. If a given application requires for the raster spacing a maximum relative error +_ Δ v/v, then - in the case of small angle?- the maximum output angle betw axes of adjacent beams 0 (2) is allowed to be where _+ A z is the depth of field. On the other hand (t-f).0(1) jjf ( 2 ) = j (2) where (? (1) is the input angle between axes of adjacent laser beams entering the equivalent lens, f is the equiva focal length and t is the object distance between the cross place of beam axes and the first principal plane of the equ valent lens. If t = f, i. e. the crossing place is at the input focal plane, than p (2) = 0, that is according to the equation (1) the depth of field Az is infinite in principl In the case of a deviation, i. e, if At = t - f (3 is not zero, then following from equations(1) and (2) Az . • < At. pf (1 ) Furthermore 0 (1) = -— . (5 Substituting equation (5) into equation (4) we get Λ Δr f 2 A "- - - ■ _- • — . (6 It is to be seen that if the relative error of the raster spacing is given, the depth of field z is inversely proportional to the deviationAt and is in direct proportion to the focal length f squared. If the tolerance of displacement of the scanning surface from the output foca plane (from the location of the output waist) +_ Az is given then the tolerance of t, that is _+ Δt can be determined from equation (6), The present invention, on the other hand, relates to an apparatus for forming and imaging laser beams, compri ing means for providing laser beams of diverging or converg¬ ing axes aπα^foptical system for imaging the laser beams ont a scanning surface. This optical system comprises an imaging element having its input focal plane at a crossing place of the laser beams or in the vicinity of the crossing place, said imaging element forming real waists of the laser beams onto the scanning surface with a predetermined waist size and with a distance between the axes of the adjacent waists, said distance corresponding to a predetermined raster spaci on the scanning surface. The method and apparatus according to the invent¬ ion have the advantage of compensating inaccurate setting of vertex points, i. e. if the input beam axes do not meet in a single point. The second advantage of the present inve ion is the extrem compactness of the bundle of laser beams throughout the whole optical system, so - in spite of having numerous laser beams - the imaging elements, e. g. lenses can have a small relative apperture, the size of deflector facets and that of other pri-3ms and mirrors can be small. This is why the invention allowes the use of less expensive, not so highly specificated imaging elements and dinamical deflector devices of small size and low inertia. Brief Description of Drawings Hereinafter, preferred embodiments of the invent ion depicted in the drawings will be presented conforming to the drawings, wherein Fig. 1 shows a schematic optical arrangement of a prior art solution, Fig. 2 illustrates a schematic optical arrangeme of an embodiment of the apparatus according to the inventi and ■ • Figs. 3 to 11 show schematic optical arrangement of further embodiments of the apparatus according to the indention. Modes for carrying out the Invention Identical elements or elements of identical func ion are referred to by identical reference signs in the drawings. Fig, 2 shows a preferred embodiment of the inven ion with two laser beams but it is suitable for a greater number of laser beams, too. The embodiment comprises a las 5, e, g.a He-Ne laser, emitting a laser beam, the waist of which with the required waist size is formed by a convergi lens 11_.* j t a required place, preferably in the middle of a modulator 6, Instead of lens 11 any other suitable imaging element, e, g. a telescopic system comprising two lenses or a setup of reflecting elements can be used. The modulat 6 can be e. g. a multi-beam acousto-optical modulator as disclosed in U. S, Patent 4,201,455. The modulator 6 gener a multiple number of individually modulated laser beams from a single input laser beam. The laser beams have their origin, the so called object-vertex in the interior of the modulator 5. Consequently, the modulator 5 performs beam-splitting, as well. By means of a converging lens 12 a real image of the vertex is formed at an image distance 2 » measured from the second principal plain of the lens 12, and also a real beam waist is formed at a distance d(2,2) from the second principal plane of the lens 12, The image vertex is further imaged by a diverging lens 13 to an image distance k 3 from the lens 13, so the image vertex is shifted to the object-side focal plane of the final converging lens 14, that is the axes of beams meet at or at the vicinity of the input focal plane of the lens 14. in such a way that the axes of adjacent beams intersect the principal plane of the lens 14 in a raster spacing r. By this means the axes of beams emerging from the lens 14 are practically parallel with one another (i. e. k 4 _ > f ^ ) , in ideal case they are really parallel ( k * x>). At the same time, the equivalent lens of the lenses 12, 13 and 14 images the input beam waist of size w(2,1) of the optical system, which is generated in the interior of modulator 6 by the lens 11, at a required distance z = d(4,2) measured from the second principal plane of the lens 14, and with the predetermined waist size w(4,2). In this case the input waist of size w(2,1) is placed in the input focal plane of the equivalent lens, forming an image waist size w(4,2) in its own output focal plane. By properly choosing the focal length and the place of the di¬ verging lens 13, the waist produced by the lens 12 is imaged by the lens 13 in such a way that the lens 14 should form an output waist at a specified place, i. e, on the scanning surface 4, and with a predetermined waist size. In accordanc with the present invention , the optical system comprising lenses 12, 13 and 14 has the advantageous adjustability of the building length of the optical system (distance between the lens 12 and the scanning surface 4) by changing focal length and placement of the lens 13, For scanning of the scanning surface 4 by laser beams, it is needed to set a dina ic deflector device (not illustrated in Fig, 2) into the path of the optical system. This can be e, g, a rotating mirror, a galvaπometric vibrat ing mirror, an acousto- or electro-optical deflector placed preferably in front of or behind the last imaging lens 14. Parameters of the optical system: focal length f 2 , f,, 4 of the lenses 12, 13 and 14, respectively and distances e 2 , and e, . between the lenses 12, 13 and 14, respectively. Input parameters for the optical system: waist size w(2,1), waist distance d(2,1), furthermore angle $2(2,1 of adjacent laser beam axes, object distance t 2 of the vertex, where and further on the first index in parenthesis designates the serial number of the imaging element, the second index in parenthesis represents whether the paramete is an input or output parameter, its value is 1 or 2 in the case of input or output parameter, respectively. An index without parenthesis designates the serial number of the imaging element. The lenses 11, 12, 13 and 14 is arranged according to the travelling direction of the laser beams an represents the 1st, 2nd, 3rd and 4th imaging element, res¬ pectively. For example, (j,1) designates the input angle of adjacent laser beam axes entering the jth imaging ele¬ ment, (j,2) designates the output angle of the adjacent laser beam axes leaving the jth imaging element. Output parameters for the optical system: waist size w(4,2) after the last imaging lens 14, waist distance d(4,2) after the last imaging lens 14, final image vertex distance k., angle (4,2) of adjacent laser beam axes after the last imaging lens 14, distance z between the back principal plane of the last imaging lens 14 and the scannin surface 4, and raster spacing r on the scanning surface 4, According to a preferred embodiment, the input waist for the last imaging lens 14 is formed by the means of lenses 12 and 13 at a distance of approximately double focal length, that is (4,1)^ 2f 4 , and so z = d(4,2) Λ 2f In this case the lens 14 has a magnification of nearly unity concerning the weist size, i. e, w(4,2) p_ w(4,1), simultaneously the angular magnification for the laser beam axes is nearly zero, 5 If f 4 ^ f F (4,1)^f F (4,2), where £ " . 2 (j,k) fp . jΛ) = --K-- is the so called Rayleigh-raπge (or Fresπel-focus) , then this optical setup is insensitive to changes of input waist " • o distance d(4,1) and vertex object distance t 4 » So a loose tolerance of adjustment is acceptable, that is why the changes d(4,1) and 4 due to a deflection can be tolerated, when a deflection element, e, g, a rotating pαligσn mirror, is inserted before the last imaging lens 15 i # At the same time the effective (illuminated) relative apperture is as follows: 3 . 4 ^ — ~ T where the waist size w. measured on the principal planes 20 of imaging lens 14 is suitably small. Another preferred embodiment is shown in Fig, 3 with two laser beams, but it is also suitable for more lase beams. In this case the task of thelens 11 of Fig, 2 is fulfilled by a converging lens 21 and a diverging lens 22, 25 the task of the lens 12 is fulfilled by a diverging lens 23, a converging lens 24 and a converging lens 25, the task of the lens 13 is fulfilled by a diverging lens 26 and the task of the lens 14 is fulfilled by a converging lens 27. 30 The existence of thessction between lenses 24 and 25, where the axes of the laser beams are parallel and the individual laser beams are well collimatβd, makes the subsystem being made up of the lenses 25, 26 and 27 freely shiftable along the optical axis. The shiftability has great importance in equipments accomplishing the scanning function by this shift along one of the scanning directions. E, g, drum plotters usually have a translation stage carrying the focusing optics. For putting into pract it is necessary to place a non-dynamic deflecting element ( a mirror or a priSm) between the lenses 24 and 25 and another deflecting element in the translation stage. For the modulator 6 the laser beam waist of required size and required placement (favourably in the interior of the modulator 6) is created from the laser beam emerging from laser 5 by the beam narrower telescop being made up of the converging lens 21 and the diverging lens 22. The other telescopic system being made up of the diverging lens 23 and the converging lens 24 has two funct It renders parallel the axes of the laser beams, i. e. k, _ f,, and it colli ates the individual laser beams, i. e d(4,2) ^> f 4 and w(4,2)> w(3,1 ). This can be realized by putting the input focal plane of the equivalent lens of the subsystem comprising lenses 23 and 24 close to the obj vertex emerging in the multi-beam modulator 6, The lens 23 transforms the laser beam parameters by reducing the size of the laser beam waist, so helping the lens 24 to become able to collimate the individual laser beams to a higher extent and to shift the waist of size w(4,2) into the distance. This is so, because a lens is able to collimate a laser beam properly if the parameter p, defined as follo is small, £. w 2 (j,1) P = Λ.. . where w(j,1) is the input waist size of a laser beam entering the jth imaging element, _ , is the wavelength, f. is the focal length of the jth imaging element. The subsystem being after the lens 24 can be made up according to the subsystem of Fig, 2 comprising the lenses 12, 13 and 14. A further embodiment of the invention can be realized by replacing the multi-beam modulator 6 being used in embodiments demonstrated in Figs,2 and 3 by a device, which comprises at least one beam splitter generating a multitude of laser beams and light intensity modulators inserted in the path of the individual laser beams. The modulators can be individual modulators of acousto-optical, electro-optical or other type, or monolithically formed bulk or thin layer integrated optical modulators driven indepen- dently. All of these can be single-beam or multi-beam modu¬ lators. Fig. 4 shows an embodiment of the invention om¬ prising a beam splitter 30 constructed of mirrors 30A, 30B and 30C, and individual electro-optical modulators 36A, 363 and 360. ^ig. 4 shows three laser beams, but the number of the laser beams can be increased by applying further beam splitter mirrors. The beam splitter 30 comprises the mirrors 30C and 30B being partially transparent and the mirror 30A being a total one. The position of the object vertex is set by adjustment of the angles of the mirrors 30A, 30B and 30C, Converging lenses 31A, 31B and 3 C are used to form the first, second and third laser beams (to adjust the size and location of the laser beam waists). The task of the lenses 12, 13 and 14 of Fig, 2 is fulfilled by a converging lens 32, a diverging lens 33 and a con¬ verging lens 34 of Fig, 4. The beam splitter 30 can be re¬ placed by other type of beam splitters, e. g, optical fibres priS s or other devices can be used. A further embodiment of the invention can be created if further imaging elements according to the lenses 23 and 24 of the collimator setup of Fig, 3 are inserted into the embodiment of Fig, 4, so the subsystems on either side of the collimated interval are shiftable along the optical axis. Fig. 5 shows an embodiment where the role of the diverging lens 13 of Fig, 2 is taken over by a converging lens 43. This setup permits the use of longer building leng In the embodiment shown in Fig, 6 the task of the lenses 12 and 13 of Fig. 2 is fulfilled by a converging lens 52, This reduces the angle between axes of adjacent laser beams, forms the image of vertex or the images of the vertexes at the vicinity of the input (in this case frontal focal plane of the last imaging lens 53 and forms the laser beam waist of required size and location for the last imagi lens 53. In the embodiment shown in Fig. 7 the task of the laser 5 and the multi-beam modulator δ of Fig. 6 is ful- filled by three lasers 65.., 65B and G5C, if they are inter¬ nally modulated, then in themselves, if not, then they have serially connected individual light intensity modulato (not shown in Fig. 7), and converging lenses 51A, 613 and 61G take part in forming of the waists of the first, second and third laser beams, respectively. A converging lens 62 fulfills the task of the lens 52 of Fig. 6. Another embodiment of the invention can be creat¬ ed by omitting the lenses 61A, 61 B and 610, This can be done if the original sizes of waists of the laser beams emerging from lasers 65A, 65B and 650 are suitable to form the required spot size (waist size) on the scanning surface 4 without the imaging lenses 61A, 61B and 61C, In the embodiment shown in Fig, 8 lasers 75A, 75B and 75C are shaped and placed in such a wςy, that the place of the object vertex and the- location of the beam waists, the angle of axes of the adjacent laser beams and waist size are appropriate for the converging lens 7 , without the use of an angle reducing optics, A further embodiment of the invention can be created by replacing the lenses 32 and 33 of Fig. 4 by a single converging or diverging imaging element, which one fulfills the task of the lens 52 of Fig, 5, In the embodiment according to Fig, 9 a diverg¬ ing lens 82 is used instead of the converging lens 63 of Fig, 7. in such a way, that the diverging lens 82 is placed in front of the input vertex approximately at a distance of its focal length, and the waists of size of w(1,2) = w(2, are formed by converging lenses 81A and 813 so that the lens 82 forms the real waists of size of w(2,2) at the scanning surface 4 with quasi parallel laser beam axes. Therefore the lens 62 of Fig, 7 ' can be omitted. The embodiment shown in Fig. 10 corresponds to the embodiment of Fig. 9 with the difference that instead of converging laser beams diverging modulated laser beams are produced by a single laser 5 and a single multi-beam acousto-optical modulator 6, and instead of the single imaging lens 82 two imaging lenses 92 and 93 are used. The converging lens 92 has three tasks: on the one part it forms a beam waist of required size and required location for the diverging lens 93 (behind the lens 93), on the other part it forms an image of the object vertex emerging from the interior of modulator 6 at the vicinity of the input focal plane (in this case at the back focal plane) of the lens 93, on the third part it produces the proper angles of axes of the adjacent laser beams entering the lens 93 for the predetermined raster spacing in the scanning surface 4. In the embodiment shown in Fig. 11 the input waist w(2,1) for the modulator 6 and for a converging lens 102 is formed by a converging lens 101, The lens 102 forms the output waists on the scanning surface 4, whilst collimates the axes of laser beams in such a way, that they intersect the scanning surface 4 with the predetermined raster spacing

Claims: Claims 1. Λ method for forming and imaging laser beams, comprising generating laser beams with diverging or con¬ verging axes and imaging each of the laser beams by means 5 of an optical system onto a scanning surface in such α way that each of the laser beams provides a predetermined spot size on the scanning surface and the axes of adjacent laser beams intersect the scanning surface v/ith a distance from aach other, whir.'n corresponds to ε predetermined 0 rαs or spacing on the scanning surface, c h c r a c t e - r i z e d in that a first crossing place of the axes of the laser beams and waists of the laser beams are formed at an input focal plane, or ir, the vicinity of an input focal plane, of an equivalent lans corresponding to that 5 subsystem of the optical system w ich forms the image of said crossing place, and the scanning surface is placed at an output focal plans, or in the vicinity of an output focal plane of said equivalent Ions, 2. The method as claimed in claim 1 , c h a - C r r c t s r i z e c' by generating the laser beams enter¬ i n g the optical subsystem corresponding to the ecuivrle t lens in such a wry that the angle between adjacent axes of the laser beams multiplied by the focal length of the equivalent lens gives at lssst approximately the raster 5 spacing. 3. The method as claimed in claim 1 or claim 2, c h a r a c t e r i z e d by adjusting the waist radius of the laser beams entering the optical subsystem corres¬ ponding to the equivalent lens to such a value that the C beam divergence half angle, determined by said waist radius, mult iplied by the focal length of the equivalent lens givesαt least approximately the spot radius pre¬ determined on the scanning surface. 6 b,, T τhne° aappppaarrrrttuuss aass ccirinac: in claim , c n a - r s c t e r i z e d in that said optical system comprises 2 further imagi g element (12, 13; 25; 32, 33; 42, 43; 52; "2; £2) rec2c'i g said imaging element (1 , 27, 3^, - , 53, S3, 71 , C2, S3, 1C2), s~id further imagi-g element red ci ^ : ;o COT.'SΓ 03 or !i 3 r en c 3 "-la e t e e n a jacent 1 r s 2 r arms. 7. τ lιs apparrtus as claimed in claim 6, c h a - r a c t a r i z e d in that said further imaging element (12, 13; 25; 32, 33; i"≥, 3; 52; S2; 92) consists of at la-st a diverging or converging la ""s or a combi ation th_rso 3. The apparatus as claimed in any of claims _ * -^__ 4 to 7, c h a r a c t e r i z e d in that said means for providing laser beans comprise several lasers (65Λ, *_5C, 55C; 75-, 75G, 75C ; S5A, 85G) emitting laser beams meeting at least approximately at a point, 9, The apparatus as in claim S, c h a r a c ¬ t e r i z a d by comprising intensity modulators (85A, 86B) placed after the lasers (35., 853). 10. The apparatus as claimed in any of claims 4 to 7, c h a r a c t e r i z e d in that said means for providing laser beams comprise a laser (5) and a beam splitter (30) for generating several laser beams from a single laser beam of said laser (5), and after the beam splitter (30) modulators (36A, 36B, 36C) are placed for providing independent Intensity modulation of the laser beams. 11, The apparatus as claimed in any of claims 4 to 7, c h a r a c t s r i z e d in that said means for providing laser beams comprise a laser (5) and means for generating several laser beams from a singls laser beam of said laser (5), said generating means are constructed as a modulator (5) for indspendent intensity modulation of the laser beams. LIST OF THE REFERENCE SIGNS CF THE DRAWINGS 1 lens 2 location 3 location 4 scanning surface 5 laser 5 modulator 1 lens 2 lens 3 lens 4 lens 1 lens 2 lens 3 lens 4 lens 5 lens 5 Isns 7 lens 0 beam splitter CΛ, G, 3 mirror 1A, G, C Isns 2 lens 3 lens 4 lens 6Λ, G, C modulator 1 lsns 2 lens 3 lens 4 lens 1 lsns 2 lens 3 lsns 1Λ, G, C lens - 2 - 62 lsns 63 lens , 3 , C laser 71 lens 75A, laser ©j- J. . I , — ___ •- lens 82 lens 85A, laser ) θ.-\ modulator 91 l3.,S 22 lens 93 lens 101 1-..S 102 lens J 1 distance distance 2, distance dist ance f focal lengt k image distance I point r raster spacing t object distance T point /vertex/ w.« waist size w 2 waist size z distance 7 (1) angle 7 (2) angle

Inventors: CSIPKA LASZLO, HORVATH GYOEZOE, OETVOES LASZLO, PLOSZ BELA, TOEKES SZABOLCS, VERMES PETER, CSIPKA, LASZLO, HORVATH, GYOEZOE, OETVOES, LASZLO, PLOSZ, BELA, TOEKES, SZABOLCS, VERMES, PETER
Applicants: ITEX KUTATO FEJLESZTOE TERMELO, ITEX KUTATO-FEJLESZTOE-TERMELOE EGYESUELES
Application year: 1986
Main classification: G11B7
IPC codes: G02B27