CN101813458B - Method and device for measuring optical axis and gap of lens group by differential confocal internal focusing method - Google Patents
Method and device for measuring optical axis and gap of lens group by differential confocal internal focusing method Download PDFInfo
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- CN101813458B CN101813458B CN2010101218354A CN201010121835A CN101813458B CN 101813458 B CN101813458 B CN 101813458B CN 2010101218354 A CN2010101218354 A CN 2010101218354A CN 201010121835 A CN201010121835 A CN 201010121835A CN 101813458 B CN101813458 B CN 101813458B
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Abstract
The invention relates to method and device for measuring an optical axis and a gap of a lens group by a differential confocal internal focusing method, belonging to the technical field of optical precision measurement. The method comprises the following steps of: firstly accurately regulating the optical axis of the measured lens group by combining an internal focusing objective with an autocollimation method; then realizing the high-accuracy positioning of each surface of the measured lens group by utilizing a differential confocal focus-fixing principle, and acquiring a numerical aperture angle of a differential confocal light cone positioned on each positioning point; finally sequentially calculating each gap of the measured lens group by utilizing a ray tracing recursion formula, and also leading an annular optical pupil into a measuring optical path to form a hollow measuring light cone so as to reduce the influence of astigmation on a measurement result. The invention combines a differential confocal technology with an internal focusing technology, has high measurement accuracy, high speed, simple system structure, long working distance, no need for disassembling the measured lens group in a measuring process, and the like and can be used for the non-contact high-accuracy measurement of the optical axis and the gap of the lens group.
Description
Technical field
The invention belongs to technical field of optical precision measurement, relate to a kind of differential confocal internal focusing method mirror group optical axis and gap measuring method and device, can realize under the situation of not dismantling the mirror group that the contactless high-precision in mirror group optical axis and gap is measured.
Technical background
In optical field, the measurement in mirror group optical axis and gap is significant.In the assembling process of photo-etching machine objective lens, the contour performance optical system of camera space, need carry out accurate adjustment to lens gap, radial deflection and optical axis drift angle according to optical axis, radius-of-curvature and the refractive index of lens in the camera lens.With the photo-etching machine objective lens is example, and each signal-lens inclined light shaft or gap deviation all can cause aberrations such as the spherical aberration, astigmatism, coma, distortion of lithographic objective, influences the image quality of object lens.Therefore the measurement to mirror group optical axis and gap need reach higher measuring accuracy.
At present, the gap in the mirror group between each lens mainly relies on the precision of machining and assembling to guarantee, can survey high method by contact in the assembling process, in conjunction with the gap between signal-lens THICKNESS CALCULATION lens.The Mirau interferometer can carry out hi-Fix to the single element lens outside surface in the installation process by replacing the contact method, realizes lens arrangement accurately, but can't go deep into mirror group inside a plurality of lens surfaces is carried out hi-Fix.
The method of domestic and international existing clearance measurement can be divided into contact type measurement and non-contact measurement two big classes.
Contact type measurement has two kinds usually: the one, and the distance on the last summit of the last summit of the last lens of measurement and back one lens deducts lens thickness then.The 2nd, measure the distance of sphere summit to the microscope base end face.The major defect of contact type measurement is to scratch lens surface easily.For avoiding scratching, between measuring head and measured surface, add one deck protection sheet usually, so measuring accuracy is lower.Some is coated with the surface of special rete, forbids contact type measurement.For assembling the mirror group of finishing, then need to measure after the dismounting, dismantle and ressemble process and all can introduce error, so contact type measurement is not suitable for the high-acruracy survey in gap.
The non-contact gap measurement mainly contains image measurement method, the confocal method of white light and interferometric method.
In " based on the fit-up gap Research on on-line-measuring of image measurement technology " literary composition of delivering in " sensor technology " in 2005, introduced a kind of on-line measurement scheme based on image measurement technology, the picture that the gap becomes in ccd video camera by optical system is delivered image measurement software processes and analysis, provide the result by Survey Software.In the mirror assembling part, can measure the gap between a plurality of lens in real time.But owing to be subjected to the influence of video camera imaging system, CCD resolving power, clear picture degree and calibration coefficient degree of accuracy etc., be difficult to the measuring accuracy that reaches higher, measuring error is in 0.015mm.For assembling the mirror group of finishing, need to measure after the dismounting, simultaneously so the image measurement method is not suitable for the high-acruracy survey in mirror group gap yet.
In " Noncontact measurement of central lens thickness " literary composition of in " GLASS SCIENCE AND TECHNOLOGY ", delivering in 2005, adopt the confocal method of white light to measure lens center thickness.The probe that this method at first utilizes behind the white light scioptics axial aberration to form positions the measured lens surface vertices, then the thickness by measured lens upper and lower surface summit spectrum of reflected light information calculations lens.The method also can be applied to measure the gap between the mirror group, and its characteristics are to realize real-time measurement, but white light is an incoherent light, focuses sensitivity and resolving power is lower, operating distance limited (3 μ m-25mm).Particularly be difficult to the refractive index of accurate known measured lens at the different wave length place, general all is by measuring the refractive index interpolation gained of certain wave strong point, because this parameter is bigger to the influence of measurement result, so this method is difficult to the measuring accuracy that reaches higher in actual applications.
Chinese patent " non-contact optical system airspace surveying work the method and apparatus " (patent No.: 01133730.3), adopt and interfere Positioning Principle, realized the non-cpntact measurement of airspace.In mirror group installation process, the method can replace the contact altimetry to guarantee the airspace between the lens in the mirror group, by mobile standard lens, can realize accurately location to the two lens upper surface summits that order is installed, the thickness of the lens of installing after deducting with the amount of movement of twice location of standard lens can obtain the airspace between two lens.This method is by the focus of standard lens location, and its bearing accuracy can reach λ/more than 20, have higher measuring accuracy.Simultaneously the method belongs to non-contact measurement, has measured lens not damaged, advantage such as easy to use.But then can't go deep into its inside and carry out clearance measurement for assembling the mirror group of finishing.
Use more polarization interference method in addition, for example: United States Patent (USP) " Optical gapmeasuring apparatus and the method " (patent No.: 5953125), propose a kind of high speed and measured the optical means and the device of two surface spacings, wherein first surface is the part of substantially transparent parts, second surface is a test object surface, earlier light beam is mapped to first surface by polarization member with an angle of inclination with lens, and measuring beam is positioned on the tested surface, utilize again that the luminous effect of closing of folded light beam makes light beam pass through the transparent component back reflection on first surface and the tested object surface, then, measure the intensity and the relative phase of the polarized component that limits by plane of incidence with polarization sensitive intensity detector and phase detector, analyze these measurement parameters, can obtain two surface gap.United States Patent (USP) " Gap measuring apparatususing interference fringes of reflected the light " (patent No.: 4932781) in addition similarly.The characteristics of polarization interference method are that measuring speed is fast, measuring accuracy is high.Measure the tested person body surface with respect to the minim gap between the parallel surfaces of transparent component but this method is mainly used at present, can't realize the high-acruracy survey in gap between the interior a plurality of lens of mirror group.
Realize that the key that mirror group internal clearance is measured has 3 points, it at first is the optical axis of determining the measured lens group, be to realize a kind of optical alignment technology then with contactless chromatography ability of high precision, big operating distance, last calculation of Gap algorithm can the inner a plurality of lens of compensating glass group to measuring the influence of light path.
At present, the optical axis deviation of lens mainly adopts the interior focusing object lens to eliminate in conjunction with autocollimation method, and this technology changes the numerical aperture angle of emergent light by regulating the axial location of the focusing group in the interior focusing object lens, in conjunction with autocollimation method, the center of correcting lens is inclined to one side well.In " inclined to one side auto testing instrument Control System Design in infrared objective center and realization " literary composition of for example in " Hunan Industrial Professional Technology Academe journal ", delivering in 2007, it adopts reflective autocollimation principle, use the CCD received signal, and with the interior focusing objective lens design full-automatic, the measured lens of focusing control system of rotation automatically, thereby realize measurement to lens axis.
In recent years, the differential confocal technology fast development in micro-imaging field is both at home and abroad compared with the confocal light path of tradition and to be had better chromatography ability, higher axial location pointing accuracy, stronger environment interference.Chinese patent " differential confocal the scanning detection method " (patent No.: 200410006359.6) for example with high spatial resolution, it has proposed the ultra-discrimination differential confocal detection method, make the system axial resolving power reach nanoscale, and significantly improved environment interference, but differential confocal technology mainly is applicable to microcosmic micrometering field, and this technology is merged mutually with interior focusing object lens autocollimation method, the optical axis that is applied to lens in the mirror group detects and surface alignment, then realize the report of the high-acruracy survey in mirror group optical axis and gap, do not see as yet up to now.
Summary of the invention
The objective of the invention is to have proposed a kind of differential confocal internal focusing method mirror group optical axis and gap measuring method and device in order to solve the contactless high-precision problems of measurement of mirror group optical axis and gap under the situation of not dismantling the mirror group.The present invention realizes the high precision adjustment of mirror group optical axis in conjunction with internal focusing method; The characteristic that differential confocal light cone summit overlaps with each surface vertices of measured lens group when utilizing differential confocal response curve zero crossing, the accurate location of realizing each surface vertices of mirror group is realized the high-acruracy survey in mirror group gap then by the ray tracing algorithm.
The objective of the invention is to be achieved through the following technical solutions.
As shown in Figure 1, differential confocal internal focusing method mirror group optical axis and gap measuring method is characterized in that:
(a) at first, adjust the optical axis of measured lens group, make itself and interior focusing object lens common optical axis;
(b) then, regulate the interior focusing object lens, the differential confocal light cone summit of its outgoing is scanned along optical axis direction, determine that by the actual zero point of surveying the differential confocal response signal differential confocal light cone summit and each surface vertices of measured lens group coincide, and write down the numerical aperture angle α of each coincide point place interior focusing object lens emergent light successively
1, α
2..., α
m, wherein m is the total light transmission face number in the measured lens group;
(c) according to known parameters: the height h of interior focusing object lens outgoing light cone
0, the radius-of-curvature r of a plurality of single element lens in the measured lens group
1～r
m, refractive index n
0～n
mNumerical aperture angle α with interior focusing object lens emergent light
1～α
m, can calculate each gap of measured lens group by the ray tracing recursion formula.
Ray tracing recursion formula in differential confocal internal focusing method mirror group optical axis and the gap measuring method step (c) satisfies:
n＝1，2，…m-1
Initial parameter: α wherein
0'=α
N+1, d
0=0, l
0'=| h
0/ tan α
N+1-h
0/ tan α
1|, d is satisfied in the gap in the measured lens group between n light transmitting surface and n+1 the light transmitting surface
n=l
n'.
In differential confocal internal focusing method mirror group optical axis and the gap measuring method step (a), adjust the method for the optical axis of measured lens group, have following two kinds:
(1) uses autocollimation method to adjust the optical axis of measured lens group, at first regulate the interior focusing object lens, the differential confocal light cone summit of its outgoing is scanned along optical axis direction, the picture point when surveying each surperficial centre of sphere of light cone summit arrival measured lens group by light intensity sensor; Adjust the measured lens group simultaneously, when rotation measured lens group, till the position of a plurality of surperficial centre of sphere picture points is not moved, this moment measured lens group and interior focusing object lens common optical axis.
(2) use autocollimation method to adjust the optical axis of measured lens group, at first regulate the interior focusing object lens, the differential confocal light cone summit of its outgoing is scanned along optical axis direction, the picture point when surveying each surperficial centre of sphere of light cone summit arrival measured lens group by light intensity sensor; Adjust the measured lens group simultaneously, when a plurality of surperficial centre of sphere picture points overlap till, this moment measured lens group and interior focusing object lens common optical axis.
The method can also utilize annular pupil to block paraxial rays, forms hollow measurement light cone, cuts down the influence of aberration to measurement result.
As described in Figure 3 differential confocal internal focusing method mirror group optical axis and gap measuring apparatus comprise first spectroscope, interior focusing object lens and differential confocal system; Wherein first spectroscope, interior focusing object lens and measured lens group are successively placed on the exit direction of light, and the differential confocal system is placed on first spectroscopical reflection direction, measured lens group surface with first spectroscope with beam reflection to the differential confocal system.
Differential confocal system in the device comprises second spectroscope, first light intensity sensor and second light intensity sensor; The light that is reflected by first spectroscope enters the differential confocal system, and by second spectroscope light is divided into two-way, and one the tunnel is radiated at and is positioned on the first defocused light intensity sensor, and another road is radiated on second light intensity sensor that is positioned at before burnt.
Differential confocal system in the device also comprises second spectroscope, burnt preceding pin hole, defocused pin hole, first light intensity sensor and second light intensity sensor; The light that is reflected by first spectroscope enters the differential confocal system, and by second spectroscope light is divided into two-way, leads up to be radiated on first light intensity sensor behind the defocused pin hole, and another road is radiated on second light intensity sensor after by pin hole before burnt.
Differential confocal system in the device also comprises second spectroscope, burnt preceding microcobjective, defocused microcobjective, first light intensity sensor and second light intensity sensor; Wherein the object plane of defocused microcobjective is positioned at defocusedly, places first light intensity sensor at it as the plane, before the object plane of microcobjective is positioned at Jiao before burnt, places second light intensity sensor at it as the plane; The light that is reflected by first spectroscope enters the differential confocal system, and light is divided into two-way by second spectroscope, lead up to and be imaged on first light intensity sensor behind the defocused microcobjective, another road is imaged on second light intensity sensor after by microcobjective before burnt.
Also comprise main control computer and electromechanical controlling device in the device; Main control computer obtains the differential confocal response signal by light intensity sensor; Main control computer is regulated the numerical aperture angle of interior focusing object lens emergent light by the controller controller for electric consumption, realizes that differential confocal light cone summit moves along the scanning of optical axis direction.
Beneficial effect:
The present invention contrasts prior art and has following innovative point:
1. this mirror group optical axis and gap measuring method utilize differential confocal to focus principle the contactless high-precision location are realized on each surface of measured lens group, need not to dismantle the measured lens group in the measuring process, and to lens not damaged in the measured lens group, measuring speed is fast.
2. the present invention is merged differential confocal technology mutually with interior focusing object lens autocollimation method, can realize the accurate adjustment of measured lens group optical axis, has reduced the measuring error in gap.
3. in light path, use the interior focusing object lens, adopt each the surface vertices position of method scanning measured lens group that changes emergent light numerical aperture angle, not only dwindle the range ability of mechanism, and strengthened the operating distance of device, increased the degree of depth that light cone enters mirror group inside.
4. in measuring light path, introduce annular pupil, block paraxial rays, form hollow measurement light cone, cut down the influence of aberration measurement result.
The present invention contrasts prior art and has following remarkable advantage:
1. utilize the good chromatography ability of differential confocal system to realize the accurate location of lens surface in the mirror group.
2. utilize the high axial resolution of differential confocal system to significantly improve measuring accuracy.
3. utilize the interior focusing object lens can realize accurate adjustment and location fast to measured lens group optical axis in conjunction with autocollimation method.
4. differential working method can be cut down the influence of environmental interference such as air turbulence to measuring accuracy.
Description of drawings
Fig. 1 is differential confocal internal focusing method mirror group optical axis of the present invention and gap measuring method synoptic diagram;
Fig. 2 adjusts the optical axis synoptic diagram for autocollimation method of the present invention;
Fig. 3 is differential confocal internal focusing method mirror group optical axis of the present invention and gap measuring apparatus synoptic diagram;
Fig. 4 is a differential confocal system schematic of the present invention;
Fig. 5 is a differential confocal system schematic of the present invention;
Fig. 6 is a differential confocal system schematic of the present invention;
Fig. 7 is differential confocal internal focusing method mirror group optical axis of the present invention and clearance measurement embodiment synoptic diagram;
Wherein: the 1-pointolite, 2-first spectroscope, 3-interior focusing object lens, 4-annular pupil, 5-measured lens group, 6-differential confocal light cone summit, the 7-adjustment rack, 8-differential confocal system, 9-first light intensity sensor, 10-second light intensity sensor, 11-second spectroscope, the defocused pin hole of 12-, pin hole before Jiao 13-, the defocused microcobjective of 14-, microcobjective before Jiao 15-, the 16-electromechanical controlling device, the 17-main control computer, the fixing group of 18-interior focusing object lens, 19-interior focusing object lens focusing group, the fixing group of 20-interior focusing object lens, the three-dimensional platform of adjusting of 21-, the 22-panoramic table, 23-measured lens group first surface, 24-measured lens group second surface.
Embodiment
The invention will be further described below in conjunction with drawings and Examples.
The present invention is merged differential confocal technology mutually with the interior focusing technology, and its basic thought is: utilize the interior focusing object lens in conjunction with autocollimation method, measured lens group optical axis is accurately adjusted; Utilize differential confocal technology that each surface of measured lens group is accurately located, realized that the contactless high-precision in mirror group optical axis and gap is measured.In measuring light path, introduce annular pupil simultaneously, block paraxial rays, form hollow measurement light cone, cut down the influence of aberration measurement result.
Adopt two separation object lens as measured lens group 5 among the embodiment, known its parameter satisfies the correctness that is used to check the described method of this patent, and wherein the radius-of-curvature of each lens is followed successively by r as shown in Figure 2 from left to right in the mirror group
1=195.426mm, r
2=-140.270mm, r
3=-140.258mm, r
4=-400.906mm; Refractive index is followed successively by from left to right: n
0=1, n
1=1.5143, n
2=1, n
3=1.668615, the thickness of known lens and be d at interval
0=12mm, d
0=0.323mm, d
0=10mm.
Embodiment 1
As Fig. 4 and shown in Figure 7, differential confocal internal focusing method mirror group optical axis and gap measuring apparatus, comprise pointolite 1, be successively placed on first spectroscope 2, interior focusing object lens 3 and the annular pupil 4 of pointolite 1 emergent light direction, also comprise the differential confocal system 8 that is placed on first spectroscope, 2 reflection directions; Measured lens group 5 surface with first spectroscope 2 with beam reflection to differential confocal system 8, second spectroscope 11 in the differential confocal system 8 is divided into two-way with light, indirect lighting is positioned at the first defocused light intensity sensor 9, and transillumination is positioned at the burnt second preceding light intensity sensor 10.
Also comprise adjustment rack 7, main control computer 17 and electromechanical controlling device 16 in the device.Adjustment rack 7 is used for fixing measured lens group 5 and adjusts measured lens group 5; Main control computer 17 obtains the differential confocal response signal by light intensity sensor; Main control computer 17 is connected with electromechanical controlling device 16, makes it drive moving of interior focusing object lens focusing group 19, thereby move in the scanning of optical axis direction on realization differential confocal light cone summit 6.
As Fig. 4 and shown in Figure 7, differential confocal internal focusing method mirror group optical axis and gap measuring method, its measuring process is:
At first, measured lens group 5 is positioned on the adjustment rack 7, and adjustment rack 7 is adjusted platform 21 by three-dimensional and is constituted with panoramic table 22, starts the Survey Software in the main control computer 17, import the correlation parameter of measured lens group 5, comprise the refractive index of measured lens group 5 interior each surperficial radius-of-curvature and each medium.
Then, open pointolite 1, its light that sends forms hollow measurement light cone behind first spectroscope 2, interior focusing object lens 3 and annular pupil 4; Measure light cone and after reflecting through annular pupil 4, interior focusing object lens 3 and first spectroscope 2 once more after 5 surface reflections of measured lens group, enter differential confocal system 8; As shown in Figure 4, second spectroscope 11 in the differential confocal system 8 is divided into two-way with light, and indirect lighting is positioned at the first defocused light intensity sensor 9, and transillumination is positioned at second light intensity sensor 10 before burnt.
By adjusting adjustment rack 7, adjust optical axis by adopting autocollimation method, make measured lens group 5 and interior focusing object lens 3 common optical axis, avoid the measuring error that causes because of light shaft offset, set-up procedure comprises following four steps:
One, main control computer 17 drives moving of interior focusing object lens focusing group 19 by controller controller for electric consumption 16, and the differential confocal light cone of its outgoing is scanned along optical axis direction;
Two, as shown in Figure 2, when differential confocal light cone summit 6 is scanned up near the centre of sphere of measured lens group first surface 23, the light that returns by measured lens group first surface 23 autocollimations by interior focusing object lens 3 after, reflexed to differential confocal system 8 by first spectroscope 2, and imaging on first light intensity sensor 9, be designated as the picture point A of measured lens group first surface 23.When picture point A is the most clear, the position coordinates of main control computer 17 record picture point A;
Three, continue moving of control interior focusing object lens focusing group 19, adopt and identical method during the 2nd goes on foot, determine the picture point B of measured lens group second surface 24;
Four, adjust the three-dimensional platform 21 of adjusting and overlap to picture point A and picture point B, this moment, measured lens group first surface 23 centre ofs sphere and measured lens group second surface 24 centre ofs sphere all were positioned on the optical axis of interior focusing object lens 3, i.e. measured lens group 5 and interior focusing object lens 3 common optical axis.
Carry out the measurement in gap then, main control computer 17 is regulated interior focusing object lens focusing group 19 by controller controller for electric consumption 16, and differential confocal light cone summit 6 is moved along optical axis direction scanning once more; Main control computer 17 determines that with the absolute zero point value of the differential response signal of second light intensity sensor 10 differential confocal light cone summit 6 overlaps with measured lens group 5 each surface vertices by surveying first light intensity sensor 9, and the numerical aperture angle of writing down each coincide point place interior focusing object lens 3 emergent light successively, wherein α
1=16.646 °, α
2=12.047 °, α
3=11.906 °, α
4=9.782 °; M=4 is the total light transmission face number of measured lens group.
Numerical aperture angle α with interior focusing object lens 3 emergent lights
1～α
4, sending main control computer 17 to, the Survey Software in the main control computer 17 is calculated each gap in the measured lens group 5 in conjunction with the parameter of measured lens group 5 successively by following ray tracing recursion formula:
n＝1，2，…m-1
Known parameters comprises the height h of interior focusing object lens 3 outgoing light cones in the formula
0The radius-of-curvature r of a plurality of single element lens in=6mm, the measured lens group 5
1=195.426mm, r
2=-140.270mm, r
3=-140.258mm, r
4=-400.906mm, refractive index n
0=1, n
1=1.5143, n
2=1, n
3=1.668615 and the numerical aperture angle α of interior focusing object lens 3 emergent lights
1=16.646 °, α
2=12.047 °, α
3=11.906 °, α
4=9.782 °.Iteration result is the gap d between measured lens group 5 light transmitting surfaces
1=12.005mm, d
2=0.321mm, d
3=9.994mm.
But be no more than 0.006mm by the result in present embodiment confirmatory measurement gap and the maximum deviation of known numeric value, the precision of the method is compared with the error of classic method dozens of micron, has quite high precision.In the measuring process of present embodiment, because the interior focusing object lens are unique moving components, so measuring process is very rapid, can finish the axial scanning of overall optical in half a minute, the data processing in later stage is then finished by the Survey Software in the main control computer 17, and the time of software processes is in 1 second.
Owing to before measuring beginning, adopt autocollimation method to adjust optical axis in the present embodiment, make measured lens group 5 and interior focusing object lens 3 common optical axis, avoid the measuring error that causes because of light shaft offset.Suppose optical axis deviation greater than 1 °, cause that the clearance measurement error of measured lens group 5 is respectively 0.050mm, 0.001mm, 0.040mm, therefore, embodiment proofreaies and correct by optical axis, and the clearance measurement precision is obviously improved.
As Fig. 5 and shown in Figure 7, the differential confocal system 8 with the differential confocal system 8 among embodiment 1 Fig. 7 replaces with Fig. 5 can constitute embodiment 2.Different is with embodiment 1, and after light entered differential confocal system 8, second spectroscope 11 was divided into two-way with light, and reflected light is through defocused pin hole 12 back lightings first light intensity sensor 9, and transmitted light is pin hole 13 back lightings second light intensity sensor 10 before overfocus.All the other measuring methods are identical with embodiment 1 with device.
As shown in Figure 6 and Figure 7, the differential confocal system 8 with the differential confocal system 8 among embodiment 1 Fig. 7 replaces with Fig. 6 can constitute embodiment 3.Different is with embodiment 1, after light enters differential confocal system 8, second spectroscope 11 is divided into two-way with light, reflected light through defocused microcobjective 14 backs at first light intensity sensor, 9 surface imagings, transmitted light before overfocus behind the microcobjective 15 at second light intensity sensor, 10 surface imagings; The object plane of wherein defocused microcobjective 14 is positioned at defocused, places first light intensity sensor 9 at it as the plane, before the object plane of burnt preceding microcobjective 15 is positioned at Jiao, places second light intensity sensor 10 at it as the plane.All the other measuring methods are identical with embodiment 1 with device.
This embodiment has realized the contactless high-precision measurement in mirror group optical axis and gap by a series of measure, realized differential confocal internal focusing method mirror group optical axis and gap measuring method and device, had measured lens group not damaged, measuring accuracy height, operating distance is long, system architecture is simple, advantage such as easy to use.
Below in conjunction with the accompanying drawings the specific embodiment of the present invention is described; but these explanations can not be understood that to have limited scope of the present invention; protection scope of the present invention is limited by the claims of enclosing, and any change on claim of the present invention basis all is protection scope of the present invention.
Claims (2)
1. differential confocal internal focusing method mirror group optical axis and gap measuring method is characterized in that:
(a) at first, utilize the interior focusing object lens to adjust the optical axis of measured lens group in conjunction with autocollimation method, make itself and interior focusing object lens common optical axis, its method of adjustment has following two kinds:
(1) uses autocollimation method to adjust the optical axis of measured lens group, at first regulate the interior focusing object lens, the differential confocal light cone summit of its outgoing is scanned along optical axis direction, the picture point when surveying each surperficial centre of sphere of light cone summit arrival measured lens group by light intensity sensor; Adjust the measured lens group simultaneously, when rotation measured lens group, till the position of a plurality of surperficial centre of sphere picture points is not moved, this moment measured lens group and interior focusing object lens common optical axis;
(2) use autocollimation method to adjust the optical axis of measured lens group, at first regulate the interior focusing object lens, the differential confocal light cone summit of its outgoing is scanned along optical axis direction, the picture point when surveying each surperficial centre of sphere of light cone summit arrival measured lens group by light intensity sensor; Adjust the measured lens group simultaneously, when a plurality of surperficial centre of sphere picture points overlap till, this moment measured lens group and interior focusing object lens common optical axis;
(b) then, regulate the interior focusing object lens, the differential confocal light cone summit of its outgoing is scanned along optical axis direction, determine that by the actual zero point of surveying the differential confocal response signal differential confocal light cone summit and each surface vertices of measured lens group coincide, and write down the numerical aperture angle α of each coincide point place interior focusing object lens emergent light successively
1, α
2..., α
m, wherein m is the total light transmission face number in the measured lens group;
(c) according to known parameters: the height h of interior focusing object lens outgoing light cone
0, the radius-of-curvature r of a plurality of single element lens in the measured lens group
1～r
m, refractive index n
0～n
mNumerical aperture angle α with interior focusing object lens emergent light
1～α
m, can calculate each gap of measured lens group by the ray tracing recursion formula, its described ray tracing recursion formula satisfies:
n＝1，2，…m-1
Initial parameter: α wherein
0'=α
N+1, d
0=0, l
0'=| h
0/ tan α
N+1-h
0/ tan α
1|, d is satisfied in the gap in the measured lens group between n light transmitting surface and n+1 the light transmitting surface
n=l
n'.
2. differential confocal internal focusing method mirror group optical axis according to claim 1 and gap measuring method is characterized in that: utilize annular pupil to block paraxial rays, form hollow measurement light cone, cut down the influence of aberration to measurement result.
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| CN102589853B (en) * | 2012-01-16 | 2014-01-08 | 北京理工大学 | Focal length measuring method of auto-collimating differential confocal lens |
| CN102589852B (en) * | 2012-01-16 | 2014-01-08 | 北京理工大学 | Autocollimating type confocal method for measuring focal length of lens |
| CN108801178B (en) * | 2017-05-04 | 2020-07-10 | 北京理工大学 | Differential confocal auto-collimation center deviation and curvature radius measuring method and device |
| CN107765425B (en) * | 2017-06-30 | 2019-11-19 | 长春理工大学 | Self-focusing laser scanning projection method based on symmetrical defocus double detector |
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