CN102279460A - Optical projection system - Google Patents
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- CN102279460A CN102279460A CN 201110212622 CN201110212622A CN102279460A CN 102279460 A CN102279460 A CN 102279460A CN 201110212622 CN201110212622 CN 201110212622 CN 201110212622 A CN201110212622 A CN 201110212622A CN 102279460 A CN102279460 A CN 102279460A
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Abstract
The invention relates an optical projection system, which is used for imaging an image in an object plane to an image plane. A first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eight lens are successively arranged along an optical axis from an object side to an image side and a diaphragm is arranged between the fourth lens and the fifth lens. Besides, a back focus of a combined lens set including the first lens, the second lens, the third lens, and the fourth lens is in the center of the diaphragm; a front focus of a combined lens set including the fifth lens, the sixth lens, the seventh lens, and the eight lens is in the center of the diaphragm; therefore, a doubly telecentric structure is formed based on the above-mentioned arrangement. According to the optical projection system provided in the invention, if a technology factor is selected, wherein the technology factor is expressed as K1 being equal to 1.0 and is easily realized, a lithography resolution can completely reach 15 microns, so that a technical requirement of LDI lithography equipment of a PCB can be satisfied sufficiently; moreover, an optical material with high transmissivity is selected, so that an exposure requirement with large doses can be met.
Description
Technical field
The present invention relates to a kind of projection optical system that is used for printed circuit board (PCB) (PCB) laser direct imaging (LDI) photoetching, also can be used for the projection optical system of photomechanical production and semiconductor packages photoetching.
Background technology
At present, make the field in printed circuit board (PCB) (PCB) lithography equipment, adopt the Israel Orbotech company of laser direct imaging (LDI) photoetching technique to occupy the maximum market share, in in May, 2007 Japan's exhibition, declare to have installed about 250 equipment, declare to have installed about 350 equipment in January, 2008.The minimum feature of Orbotech company lithographic equipment is brought up to 25um by 50um, even to 15um.And other LDI lithographic equipments are mainly provided by Japanese firm, and as Pentax company, Fuji company, Dainippon Screen company, these lithographic equipment minimum feature have also reached the 15um magnitude.Therefore, these LDI lithographic equipments sharply increase the needs that minimum feature 15um projection optical system can be provided.
Yet in the prior art, as the U.S. Pat 6879383 (day for announcing: on April 12nd, 2005), it adopts the catadioptric structure, compare with the total refraction structure, disadvantage is that lateral dimension is big, cause the requirement of lens material very high, the processing of especially bigbore concave mirror, detect require all very harsh; And visual field, work also are not so good as the total refraction structure apart from aspects such as, dress school requirements, costs and have bigger advantage.Moreover this patent provides among 5 embodiment of this optical system, and its operating distance only reaches 7.5mm～11mm scope, and its optics length overall reaches more than 1150mm～1200mm.In actual projection optical system is used, this operating distance will propose very harsh size restrictions to the design of work stage etc.In addition, this patent does not provide the image quality data yet, do not mention processibility, also adopt 1 aspherical optical element to increase operating distance and arrive 1150mm to 11mm, compression optics length overall, work such as the introducing of this aspherical optical element will be processed to optics, optical detection bring very big difficulty.
Chinese patent CN98113037.2 (the day for announcing: on July 23rd, 2003) provided a kind of picture side heart double gauss far away optical system, be applicable to the image-forming objective lens of precision optical instrument.This patent has provided the objective lens design data, and has provided image quality, but image quality can not satisfy the technical requirement of printed circuit board (PCB) (PCB) lithographic equipment projection optical system, and also has 2 cemented surfaces, does not also meet the technical requirement of photoetching.
Summary of the invention
The object of the present invention is to provide a kind of projection optical system that can be used for printed circuit board (PCB) (PCB) laser direct imaging (LDI) lithography equipment, it is correcting chromatic aberration effectively, and have bigger operating distance, good image quality, to reach the requirement of actual lithography application.
The present invention solves the problems of the technologies described above the technical scheme that adopted as following description:
A kind of projection optical system, be used for the pattern imaging in the object plane in the picture plane, be disposed with along optical axis direction from the object side to the image side: first to the 8th lens, diaphragm is located between the 4th lens and the 5th lens, wherein, the back focus of described first to fourth combination of lenses mirror group is positioned at the center of diaphragm, and the front focus of the 5th to the 8th combination of lenses mirror group is positioned at the center of diaphragm, forms two core structures far away by said structure.
Further, preferred construction is that described diaphragm is an aperture diaphragm.
Further, preferred construction is that described first lens, the 4th lens, the 5th lens, the 7th lens, the 8th lens are the lens with positive light coke, the lens that described second lens, the 3rd lens and the 6th lens have negative power.
Further, preferred construction is that described first lens and the 4th lens are biconvex lens; Second lens are meniscus lens, and concave surface is towards the picture plane; The 3rd lens are biconcave lens.
Further, preferred construction is that described the 5th lens and the 8th lens are biconvex lens; The 6th lens are biconcave lens; The 7th lens are meniscus lens, and convex surface is towards the picture plane.
Further, preferred construction is that described first lens, second lens, the 3rd lens, the 4th lens, diaphragm, the 5th lens, the 6th lens, the 7th lens, the 8th lens are spherical lens.
Further, preferred construction is that described first lens, second lens, the 3rd lens, the 6th lens, the 7th lens, the 8th lens select for use flint glass to make.
Further, preferred construction is that described the 4th lens and the 5th lens select for use crown glass to make.
The present invention makes it compared with prior art owing to adopted above-mentioned technical scheme, has following advantage and good effect:
1, projection optical system of the present invention adopts the total refraction structure, and effectively correcting chromatic aberration improves image quality;
2, projection optical system of the present invention adopts the total refraction structure, therefore has the conjugate distance that meets the demands, long work distance, the advantage of the two hearts far away of object space and picture side;
3, only to adopt surface type be the lens of sphere to projection optical system of the present invention, do not introduce non-spherical lens, thereby reduced the difficulty in processing, detection and the dress school of lens.
Description of drawings
Below in conjunction with accompanying drawing the present invention is described in detail, so that above-mentioned advantage of the present invention is clearer and more definite.
Fig. 1 is the structure and the index path of projection optical system of the present invention;
Fig. 2 is the modulation transfer function MTF figure of projection optical system embodiment of the present invention.
Embodiment
Below will be described in further detail projection optical system of the present invention.
The object of the present invention is to provide a kind of projection optical system that can be used for printed circuit board (PCB) (PCB) laser direct imaging (LDI) lithography equipment, it is correcting chromatic aberration effectively, and have bigger operating distance, good image quality, to reach the requirement that actual exposure is used.
Usually, the applied laser direct imaging of the present invention (LDI) lithography equipment adopts the 405nm laser diode as light source, and the spectral bandwidth that requires projection optical system is 405 ± 5nm.The minimum feature of this equipment is 15um, process factor k1 select than be easier to realize 1.0, as number formulary value aperture NA be like this
This equipment requirements true field diameter is 26.53mm, is 12.28mm as square field number, and enlargement ratio is 1/2.16, and conjugate distance is 425mm, and object space work distance＞200mm is as side's work distance＞45mm.
The projection optical system constrained parameters that this lithographic equipment requires are as shown in table 1, and wherein, table 1 is being represented the projection optical system parameter of LDI lithographic equipment requirement.
The projection optical system parameter that table 1:LDI lithographic equipment requires
| The constraint project | Parameter |
| Operation wavelength | 410nm、405nm、400nm |
| Picture number formulary value aperture | 0.027 |
| The true field diameter | 26.53 |
| Enlargement ratio | |
| 1/2.16 | |
| Picture side's work distance | ＞45mm |
| Object space work distance | ＞200mm |
| Conjugate distance | 425mm |
At above-mentioned requirement restriction for projection optical system, according to one embodiment of present invention, described projection optical system, from object space S2 to being disposed with along optical axis direction as square S1: first to the 8th lens (L1～L8), diaphragm L is located between the 4th lens and the 5th lens, and wherein, the back focus of described first to fourth combination of lenses mirror group is positioned at the center of diaphragm, the front focus of the 5th to the 8th combination of lenses mirror group is positioned at the center of diaphragm, forms two core structures far away by said structure.
Wherein, among the preferred embodiment, described diaphragm L is an aperture diaphragm.
Because above-mentioned two core structure far away can guarantee that enlargement ratio is along with object plane and image planes change along moving of optical axis direction.The imaging light cone of object space and image space all is symmetrical in chief ray, and promptly the chief ray of object space and image space is parallel to optical axis, just forms the projection optical system of two core structures far away.Like this, even object plane and image planes are in the position of out of focus, the height of thing and picture does not still change on perpendicular to optical axial plane, and promptly enlargement ratio does not change, and this point is extremely important for the projection lithography technology.
In addition, among this embodiment, the described first lens L1, the 4th lens L4, the 5th lens L5, the 7th lens L7, the 8th lens L8 are the lens with positive light coke, the lens that the described second lens L2, the 3rd lens L3 and the 6th lens L6 have negative power.
And described first lens L1 and the 4th lens L4 are biconvex lens; The second lens L2 is a meniscus lens, and concave surface is towards the picture plane; The 3rd lens L3 is a biconcave lens; Described the 5th lens L5 and the 8th lens L8 are biconvex lens; The 6th lens L6 is a biconcave lens; The 7th lens L7 is a meniscus lens, and convex surface is towards the picture plane.
For the convenience of optics processing, optical detection and reduce cost, the described first lens L1, the second lens L2, the 3rd lens L3, the 4th lens L4, the 5th lens L5, the 6th lens L6, the 7th lens L7, the 8th lens L8 are spherical lens.
In addition, described projection optical system, the first lens L1, the second lens L2, the 3rd lens L3, the 6th lens L6, the 7th lens L7, the 8th lens L8 select flint glass for use, the PBL26Y optical glass of preferred OHARA company, the 4th lens L4 and the 5th lens L5 select crown glass for use, the SFPL51Y optical glass of preferred OHARA company.
According to the desired projection optical system parameter of LDI lithographic equipment in the previous table 1, the design data of projection optical system provided by the invention is as shown in table 2.Table 2 has provided the specific design parameter value of each sheet lens of the projection optical system of present embodiment, wherein, and each surperficial pairing lens between " affiliated object " hurdle has been indicated from the object plane to image planes; " radius " hurdle has provided each surperficial pairing spherical radius; " thickness/at interval " hurdle has provided the axial distance between adjacent two surfaces, if this two surface belongs to same lens, and the thickness of these lens of numeric representation of " thickness/at interval " then, otherwise expression thing/image planes are to the distance of lens or the spacing of adjacent lens." optical material " hurdle promptly indicate the material of corresponding lens, " semiaperture " hurdle indicated 1/2 aperture value on corresponding surface, i.e. half height.
With lens L1 and L2 is example, the spherical radius of the front surface 1 of L1 is 66.855341mm (its sign has been represented surperficial bending direction), the front surface 1 of L1 is 200mm to the spacing of object plane, and its optical material is PBL26Y_OHARA, and the semiaperture of L1 front surface 1 is 15.682249mm; The spherical radius of the rear surface 2 of L1 is-454.345181mm, the rear surface 2 of the front surface 1 to L1 of L1, and promptly the center thickness of lens L1 is 3.133231mm, and the semiaperture of the rear surface 2 of L1 is 15.600694mm, and promptly L1 is a biconvex lens.
The spherical radius and the semiaperture of the front surface 3 of L2 are respectively 18.376666mm and 7.525775mm, the spacing of the rear surface 2 of the front surface 3 to L1 of L2 is 51.418255mm, the optical material of lens L2 is PBL26Y_OHARA, the spherical radius and the semiaperture of the rear surface 4 of L2 are respectively 15.426309mm and 6.647455mm, the thickness of lens L2 is 3.510412mm, and promptly L2 is the bent moon negative lens of concave surface towards picture plane one side.Except representing half height of visual field, picture side the semiaperture of image planes (surperficial Image) that all the other each surperficial parameter value implications are analogized according to L1, L2.
Except these 8 lens of L1～L8, also be provided with aperture diaphragm STOP between lens L4 and the L5, the change of its aperture size will influence the imaging effect of this projection optical system.
Table 2: the design parameter of projection optical system of the present invention
Fig. 2 has shown the modulation transfer function MTF of the projection optical system of present embodiment, and it has reflected the image quality of projection optical system of the present invention.Under parameter conditions such as operation wavelength in table 1, numerical aperture, visual field, according to the analytical calculation of professional optical design software CODE_V as can be known, its aberration correction degree is as shown in table 3 below.
Table 3: projection optical system design image quality of the present invention
Adopt projection optical system of the present invention, satisfy the technical requirement that is used for printed circuit board (PCB) (PCB) laser direct imaging (LDI) lithography equipment fully, image quality is good, and reaches the requirement that actual exposure is used.
The present invention makes it compared with prior art owing to adopted above-mentioned technical scheme, has following advantage and good effect:
1, projection optical system of the present invention adopts the total refraction structure, and effectively correcting chromatic aberration improves image quality;
2, projection optical system of the present invention adopts the total refraction structure, therefore has the conjugate distance that meets the demands, long work distance, the advantage of the two hearts far away of object space and picture side;
3, only to adopt surface type be the lens of sphere to projection optical system of the present invention, do not introduce non-spherical lens, thereby reduced the difficulty in processing, detection and the dress school of lens.
It should be noted that; above-mentioned specific embodiment only is exemplary; under above-mentioned instruction of the present invention, those skilled in the art can carry out various improvement and distortion on the basis of the foregoing description, and these improvement or distortion drop in protection scope of the present invention.
It will be understood by those skilled in the art that top specific descriptions just in order to explain purpose of the present invention, are not to be used to limit the present invention.Protection scope of the present invention is limited by claim and equivalent thereof.
Claims (8)
1. projection optical system, be used for the pattern imaging in the object plane in the picture plane, it is characterized in that, be disposed with along optical axis direction from the object side to the image side: first to the 8th lens, diaphragm is located between the 4th lens and the 5th lens, and wherein, the back focus of described first to fourth combination of lenses mirror group is positioned at the center of diaphragm, the front focus of the 5th to the 8th combination of lenses mirror group is positioned at the center of diaphragm, forms two core structures far away by said structure.
2. according to the described projection optical system of claim, it is characterized in that, described first lens, the 4th lens, the 5th lens, the 7th lens, the 8th lens are the lens with positive light coke, the lens that described second lens, the 3rd lens and the 6th lens have negative power.
3. projection optical system according to claim 1 is characterized in that, described first lens and the 4th lens are biconvex lens; Second lens are meniscus lens, and concave surface is towards the picture plane; The 3rd lens are biconcave lens.
4. projection optical system according to claim 3 is characterized in that, described the 5th lens and the 8th lens are biconvex lens; The 6th lens are biconcave lens; The 7th lens are meniscus lens, and convex surface is towards the picture plane.
5. according to the arbitrary described projection optical system of claim 1～4, it is characterized in that described first lens, second lens, the 3rd lens, the 4th lens, diaphragm, the 5th lens, the 6th lens, the 7th lens, the 8th lens are spherical lens.
6. according to the arbitrary described projection optical system of claim 1～4, it is characterized in that described first lens, second lens, the 3rd lens, the 6th lens, the 7th lens, the 8th lens select for use flint glass to make.
7. as the arbitrary described projection optical system of claim 1～4, it is characterized in that described the 4th lens and the 5th lens select for use crown glass to make.
8. projection optical system according to claim 1 is characterized in that described diaphragm is an aperture diaphragm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110212622 CN102279460B (en) | 2011-07-27 | 2011-07-27 | Optical projection system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201110212622 CN102279460B (en) | 2011-07-27 | 2011-07-27 | Optical projection system |
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| CN102279460A true CN102279460A (en) | 2011-12-14 |
| CN102279460B CN102279460B (en) | 2013-01-23 |
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| CN 201110212622 Expired - Fee Related CN102279460B (en) | 2011-07-27 | 2011-07-27 | Optical projection system |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103472574A (en) * | 2013-09-16 | 2013-12-25 | 中国科学院上海光学精密机械研究所 | Photoetching projection objective with variable conjugate distance and photoetching method |
| CN106483642A (en) * | 2016-12-14 | 2017-03-08 | 舜宇光学(中山)有限公司 | A kind of doubly telecentric camera lens based on machine vision |
| CN107219616A (en) * | 2017-07-25 | 2017-09-29 | 埃卫达智能电子科技（苏州）有限公司 | A kind of image bilateral telecentric optical system of ultra-large vision field |
Citations (5)
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| SU1647492A1 (en) * | 1989-05-15 | 1991-05-07 | Предприятие П/Я А-7309 | Reproduction objective |
| JPH0961711A (en) * | 1995-08-21 | 1997-03-07 | Ricoh Opt Ind Co Ltd | Projecting lens |
| JPH1144844A (en) * | 1997-07-25 | 1999-02-16 | Fuji Xerox Co Ltd | Enlarging and projecting optical system |
| CN101021607A (en) * | 2007-03-27 | 2007-08-22 | 上海微电子装备有限公司 | Symmetrical double-telecentric projection optical system |
| CN101101365A (en) * | 2006-06-22 | 2008-01-09 | Bci财务公司 | Projection objective with fixed focal length for digital projection |
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2011
- 2011-07-27 CN CN 201110212622 patent/CN102279460B/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SU1647492A1 (en) * | 1989-05-15 | 1991-05-07 | Предприятие П/Я А-7309 | Reproduction objective |
| JPH0961711A (en) * | 1995-08-21 | 1997-03-07 | Ricoh Opt Ind Co Ltd | Projecting lens |
| JPH1144844A (en) * | 1997-07-25 | 1999-02-16 | Fuji Xerox Co Ltd | Enlarging and projecting optical system |
| CN101101365A (en) * | 2006-06-22 | 2008-01-09 | Bci财务公司 | Projection objective with fixed focal length for digital projection |
| CN101021607A (en) * | 2007-03-27 | 2007-08-22 | 上海微电子装备有限公司 | Symmetrical double-telecentric projection optical system |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103472574A (en) * | 2013-09-16 | 2013-12-25 | 中国科学院上海光学精密机械研究所 | Photoetching projection objective with variable conjugate distance and photoetching method |
| CN104991423A (en) * | 2013-09-16 | 2015-10-21 | 中国科学院上海光学精密机械研究所 | Lithography method of LDI lithography equipment in printed circuit board (PCB) lithography field |
| CN103472574B (en) * | 2013-09-16 | 2016-04-13 | 中国科学院上海光学精密机械研究所 | The photoetching projection objective lens that conjugate distance is variable |
| CN104991423B (en) * | 2013-09-16 | 2017-04-12 | 中国科学院上海光学精密机械研究所 | Lithography method of LDI lithography equipment in printed circuit board (PCB) lithography field |
| CN106483642A (en) * | 2016-12-14 | 2017-03-08 | 舜宇光学(中山)有限公司 | A kind of doubly telecentric camera lens based on machine vision |
| CN107219616A (en) * | 2017-07-25 | 2017-09-29 | 埃卫达智能电子科技（苏州）有限公司 | A kind of image bilateral telecentric optical system of ultra-large vision field |
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| CN102279460B (en) | 2013-01-23 |
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