CN104833486B - Multiple reflections formula laser differential confocal Long focal length measurement method and apparatus - Google Patents
Multiple reflections formula laser differential confocal Long focal length measurement method and apparatus Download PDFInfo
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Abstract
The invention belongs to technical field of optical precision measurement, is related to a kind of multiple reflections formula laser differential confocal Long focal length measurement method and apparatus.This method carries out multiple reflections by introducing optical parallel and speculum after measured lens to focus on light beam, this characteristic is accurately corresponded to convergent point using laser differential confocal Intensity response curve zero crossing, high-precision focus is carried out to the convergent point of different order of reflection after repeatedly turning back, reflector position information is accurately measured by length-measuring interferometer again, then realizes long-focus high-acruracy survey.Differential confocal proposed by the present invention focuses principle and turned back the method that principle is combined with multiple reflections formula, high degree have compressed optical path, measurement distance is greatly shortened, so as to reduce apparatus structure, anti- high environment resistant interference performance, available for long-focus lens or the high-acruracy survey of optical system focal length.
Description
Technical field
The present invention relates to a kind of multiple reflections formula laser differential confocal Long focal length measurement method and apparatus, belong to optical element
Parameter Technology of Precision Measurement field.
Technical background
Long focal length optical element is widely used in the large-scale optics such as laser fusion, Space Optical System and high-energy laser
In system research field.However, the high-acruracy survey of long focus length of lens value is always that optical testing art is still unsolved
A great problem, its measurement accuracy also directly affects the image quality and performance of Large optical system.Therefore, find a kind of
The high-precision measuring method of long-focus has critically important application value, and laser fusion, urban tour ism and high energy
The national key special subjects such as laser and technical bottleneck urgently to be resolved hurrily in the development and adjustment of national large project.
At present, for the high-acruracy survey of long-focus, many different measuring methods have been proposed in domestic and international researcher,
These measuring methods can generally be divided into two classes.
The first kind is the measuring method based on traditional geometry image-forming principle.Such as 1999《Journal of
Optical Technology》In deliver《Measuring the focal lengths of long-focus optical
systems》In one text, author proposes to insert a low-angle wedge in collimated light path, by measuring optical system focal plane
On with/without wedge when picture change in location obtain the measuring method of tested focal length value, this method is relative to 25000mm focal lengths
Measurement accuracy is 0.1%.For another example 1987《Applied optics》In deliver《Determination of the
focal length of nonparaxial lenses by moire deflectometry》In one text, author proposes to utilize
Moire effect, measured lens focometry is realized by measuring the Morie fringe anglec of rotation, its theoretical relative measurement error is less than
0.1%.These traditional measuring methods based on geometry image-forming principle are limited by diffraction limit, and its measurement accuracy is difficult into one
Step improves.
Second class is the measuring method based on Tabo effect, and this is also the most frequently used in current Long focal length measurement research field
Method.According to Tabo effect, when irradiating a grating with spherical light wave, caused periodicity Taibo picture and wave-front curvature radius
There is a corresponding relation, Moire fringe will be produced by placing a grating again in Taibo image planes position, be deflected according to Moire fringe
Angle realizes focometry with radius of curvature corresponding relation.Based on this principle, 1991《Applied optics》In deliver
's《Measurement of the focal length of a collimating lens using the Talbot
effct and the Moire technique》In one text, author instead of the colimated light system of complexity using a collimating mirror,
Limited by Moire fringe angle discrimination precision, it is only 2% to 200mm focal length value measurement accuracy.Judge to improve stripe angle
Precision, 2005《Applied optics》In deliver《Measurement of focal length with phase-
shifting Talbot interferometry》In one text, author filters out grating fringe using Fourier analysis technology and caused
Picture noise improve Morie fringe angle discrimination precision, focal length be 240mm under the conditions of, measurement error be less than 0.3%.China
Zhejiang University also has made intensive studies to the method, and in 2005 years《Optics And Lasers In Engineering》
In deliver《Novel method for testing the long focal length lens of large
aperture》, Tabo effect and scanning techniques be combined by author, and carrying out real time scan to measured lens diverse location measures
Tested focal length value, under bore 150mm, focal length value 18000mm length, relative accuracy is better than 0.13% for it.To be further
Measurement accuracy is improved, and in 2014《Optics express》In deliver《Long focal-length measurement
using divergent beam and two gratings of different periods》In one text, author proposes to adopt
With divergent beams and not etc. periodic optical grating substitution conventional collimated light beam and etc. periodic optical grating measuring method, it is in focal length
Under 13500mm length, relative error is less than 0.0018%.It is this kind of based on Tabo effect compared with first kind measuring method
Measuring method has reached higher measurement accuracy, but is all using stripe order recognition information as opinion scale, and in actually measuring
Interference fringe is highly susceptible to the such environmental effects such as air-flow, temperature and shake, constrains its popularization and application and survey in engineering
Accuracy of measurement further improves.
To sum up, it is optical testing art a great problem that the high-acruracy survey of long-focus, which is still, and its Major Difficulties is：
1) depth of focus is grown, and is influenceed by diffraction effect, it is difficult to accurately focus；
2) focal length is grown, and optical path length, is influenceed by measurement environmental disturbances and system drifting, it is difficult to precision length measurement；
3) focal length is grown, and the requirement of harshness is proposed to measurement system building and measuring environment, it would be highly desirable to capture and pass through small size
Measure to realize that long-focus high precision measures problem, to reduce equipment instrument, improve environment resistant interference performance.
Based on this, the present invention proposes a kind of multiple reflections formula laser differential confocal Long focal length measurement method and apparatus, the party
Method utilizes multiple reflections formula light path folding technology, reduces optical path and surveys over long distances, using differential confocal Detection Techniques, with
Axial intensity information is measurement opinion scale, has contained system common-mode signal interference, has improved environment interference.It is repeatedly anti-
Penetrate formula laser differential confocal Long focal length measurement method and provide a brand-new technological approaches for the high-acruracy survey of long-focus.
The content of the invention
The invention aims to solve the high-acruracy survey problem of long focus length of lens, it is proposed that a kind of repeatedly anti-
Penetrate formula laser differential confocal Long focal length measurement method and apparatus.This method after measured lens by introducing optical parallel and speculum
Multiple reflections are carried out to focus on light beam, this is accurately corresponded to tested mirror foci using laser differential confocal response curve zero crossing
Characteristic, high accuracy positioning is carried out to the focused spot of different order of reflection after repeatedly turning back, then realizes that long-focus is surveyed in high precision
Amount.
The purpose of the present invention is achieved through the following technical solutions.
A kind of multiple reflections formula laser differential confocal Long focal length measurement device of the present invention, including spot light, spectroscope, standard
Light intensity is visited before surface, the preceding surface of speculum, speculum, Jiao after straight lens, annular pupil, measured lens, optical parallel, optical parallel
Pin hole, Amici prism, defocused pin hole and defocused light intensity detector before survey device, Jiao, its optical path are：Spot light is opened, by point
The light of light source outgoing forms collimated light beam after spectroscope and collimation lens and is radiated on measured lens；Collimated light beam is through tested
Into measuring beam, the measuring beam folds after optical parallel between surface and the preceding surface of speculum for mirror and optical parallel post-concentration
Reflection；Along optical axis mobile mirror, the near surface before surface or speculum after measuring beam convergent point is located at optical parallel
When, measuring beam is reflected on surface or the preceding surface of speculum after optical parallel, and the light beam reflected is again reversely through parallel
Optical flat and the measured lens mirror that is split is reflected into differential confocal detection system, and detection system is by axial intensity information after processing
To differential confocal response curve, its zero crossing position accurately corresponds to measuring beam convergent point；
Multiple reflections formula laser differential confocal Long focal length measurement method of the present invention, can use it for long-focus lens
High precision test and optical system focal length the value detection of focal length value, specific measuring process are as follows：
Step 1: speculum is placed in the collimated light path after collimating mirror, speculum and collimation are adjusted using autocollimation method
Light beam is coaxial；
Step 2: optical parallel is placed in the collimated light path after collimating mirror, using autocollimation method adjust optical parallel with
Collimated light beam is coaxial；
Step 3: measured lens is placed in the collimated light path after collimating mirror, adjusts measured lens and collimated light beam is coaxial；
Step 4: along optical axis direction mobile mirror, measuring beam is set to pass through n=i between optical parallel and speculum
(i=0,1,2 ...) secondary reflection, when light beam focuses on after optical parallel near surface before surface or speculum, plane of motion reflection
Mirror, the confocal response curve of system differential is measured by differential confocal detection system, it is accurate using differential confocal response curve zero crossing
The convergent point of measuring beam is determined, now reflector position is z to recordi；
Step 5: continuing optical axis direction mobile mirror, measuring beam is set to pass through n=between optical parallel and speculum
J (j=0,1,2 ...) secondary reflection, when light beam is focused on after optical parallel near surface or speculum front face location, plane of motion
Speculum, the confocal response curve of system differential is measured by differential confocal detection system, utilizes differential confocal response curve zero crossing
The accurate convergent point for determining measuring beam, now reflector position is z to recordj；
Step 6: the reflector position information z according to recordiAnd zj, with reference to optical parallel thickness b, measured lens is put down with parallel
Brilliant axially spaced-apart d and optical parallel refractive index n0Calculate tested vertex focal length value；
Step 7: the measured lens thickness b further according to known certain margin of tolerance1, refractive index n1, surface curvature radius r11With
r12, by vertex focal length fBFD' conversion obtains tested focal length value f '；
Multiple reflections formula laser differential confocal Long focal length measurement method and apparatus of the present invention, can also be in the optical path
Increase annular pupil is modulated to measuring beam, forms annular beam, reduces influence of the ripple difference to measuring beam when focusing,
Improve measurement accuracy.
Multiple reflections formula laser differential confocal Long focal length measurement method and apparatus of the present invention, can also be to spot light
The light sent carries out intensity modulation, is detected to obtain the differential confocal of modulated system by the light intensity sensor in differential confocal measurement system
Response signal, differential confocal response curve is obtained after the modulated signal is demodulated, that improves system focuses sensitivity.
Beneficial effect
Present invention contrast prior art has following innovative point：
A kind of multiple reflections formula laser differential confocal Long focal length measurement method and apparatus is proposed, by drawing after measured lens
Enter optical parallel and speculum to convergence measurement light beam carry out multiple reflections, using laser differential confocal response curve zero crossing with
Tested mirror foci accurately corresponds to this characteristic, and high accuracy positioning is carried out to the focused spot of different order of reflection after repeatedly turning back,
Then long-focus high-acruracy survey is realized.
Present invention contrast prior art has following remarkable advantage：
1) present invention carries out multiple folding mirror to convergence measurement light beam, and optical path has been greatly shortened, has reduced survey
Over long distances, so as to shorten rail length, reduce equipment instrument, systematic survey speed and efficiency are improved, more suitable for reality
In the engineering of border.
2) in this measuring method, technology is focused with reference to differential confocal precision, evaluation is used as using the Intensity response signal of axial direction
Yardstick, measured lens depth of focus is compressed using multiple folding mirror technology, reduces the width of differential confocal response curve, had
Have and higher focus sensitivity and Focus accuracy；
3) employ non-interfering differential confocal and focus technology, it is suppressed that common-mode signal is disturbed, and has cut down air agitation etc.
Influence of the environmental disturbances to measurement accuracy, significantly improves system environment resistant interference performance and system reliability.
Brief description of the drawings
Fig. 1 is the schematic diagram of multiple reflections formula laser differential confocal Long focal length measurement system of the present invention；
Fig. 2 is the schematic diagram of multiple reflections formula laser differential confocal Long focal length measurement system embodiment of the present invention；
Fig. 3 is the schematic diagram of multiple reflections formula laser differential confocal Long focal length measurement system embodiment of the present invention；
Fig. 4 is the differential confocal response curve that the present invention is detected to obtain by differential confocal measurement system；
Wherein：1- spot lights, 2- spectroscopes, 3- collimation lenses, 4- annular pupils, 5- measured lens, 6- optical parallels, 7- are put down
Light intensity detector before surface, the preceding surface of 8- speculums, 9- speculums, 10- differential confocals detection system, Jiao 11- after optical parallel,
Pin hole, 13- Amici prisms, the defocused pin holes of 14-, the defocused light intensity detectors of 15-, 16- measuring beams, 17- spot lights hair before Jiao 12-
Image pick-up card, the defocused image pick-up cards of 22-, 23- before generating apparatus, 18- lasers, 19- optical fiber, 20- master control systems, Jiao 21-
Electromechanical controlling device, 24- rectilinear translations guide rail, 25- reflector alignments frame, 26- optical parallels adjustment frame, the adjustment of 27- measured lens
Frame.
Embodiment
The invention will be further described with reference to the accompanying drawings and examples.
Accompanying drawing 1 is the multiple reflections formula laser differential confocal Long focal length measurement system schematic of the present invention, and it includes：Point light
Table before surface 7, speculum after source 1, spectroscope 2, collimation lens 3, annular pupil 4, measured lens 5, optical parallel 6, optical parallel
Face 8, speculum 9, it is burnt before light intensity detector 11, it is burnt before pin hole 12, Amici prism 13, defocused pin hole 14 and defocused light intensity detector
15。
Embodiment 1
As shown in Fig. 2 the embodiment of the present invention is based on the multiple reflections formula laser differential confocal Long focal length measurement system shown in Fig. 1
System schematic diagram, it can also include：Image is adopted before spot light generating means 17, laser 18, optical fiber 19, master control system 20, Jiao
Truck 21, defocused image pick-up card 22, electromechanical controlling device 23, rectilinear translation guide rail 24, reflector alignment frame 25, optical parallel
Adjustment frame 26, measured lens adjustment frame 27；Wherein, spot light 1 can be made up of laser 18 and optical fiber 19；Differential confocal detection system
System 10 can be by pin hole 12, Amici prism 13, defocused pin hole 14 and defocused light intensity detector 15 before light intensity detector before Jiao 11, Jiao
Form；
As shown in Fig. 2 realize long focus length of lens using multiple reflections formula laser differential confocal Long focal length measurement method
The process of value high-acruracy survey is：The light that spot light 1 is emitted forms collimated light beam and irradiated after spectroscope 2 and collimation lens 3
On measured lens 5.The collimated light beam is being put down through measured lens 5 with the post-concentration of optical parallel 6 into measuring beam 16, measuring beam 16
After optical parallel 67, surface after optical parallel 6 is focused between the preceding surface 8 of the speculum of surface 7 and speculum 9 after folding mirror
Put or the front face location of speculum 9.The light returned by surface 7 after optical parallel 6 or the front surface reflection of speculum 9 is again
It is reflected in through optical parallel 6 and measured lens 5 mirror 2 that is split on Amici prism 13.Light path is divided into two-way by Amici prism 13, and one
The road prism 13 that is split reflects, and the position of pin hole 12 is received by light intensity sensor 11 before focusing on Jiao, and another way passes through Amici prism
13 are focused at the defocused position of pin hole 14 is received by light intensity sensor 15.Straight line is controlled by electromechanical controlling device 23 by master control system
Translating rails 24 drive speculum 9 to be moved along optical axis direction, when convergent beam 16 reflects n=i by optical parallel 6 and speculum 9
When (i=0,1,2 ...) is secondary, the light intensity signal that image pick-up card 21 and defocused image pick-up card 22 collect camera before Jiao transmits
The confocal response curve of system differential is formed to the normalized of master control system 20, its zero crossing position accurately corresponds to order of reflection n
The position z of=i speculums 9i.Continue translatable mirror 9, when convergent beam 16 reflects n=j by optical parallel 6 and speculum 9
When secondary, the differential confocal response curve zero crossing that measuring system detects accurately corresponds to the institute of order of reflection n=j speculums 9 in place
Put zj.Utilize the position z of speculum 9 during the n=i secondary reflections measurediWith n=j (j=0,1,2 ...) it is secondary when speculum 9 where
Position zjTry to achieve tested focal length value.
Exemplified by measuring n=3 secondary reflections and n=4 secondary reflections successively：
When measured lens 5 use planoconvex spotlight of the bore for D=150mm, its convex radius r=4998.8608mm,
The thickness b=10mm of optical parallel 6 used, refractive index n=1.5146mm, d=is spaced between measured lens 5 and optical parallel 6
During 319.62mm, and plane is used towards collimation light direction, multiple reflections formula laser differential confocal Long focal length measurement device such as Fig. 2 institutes
Show, its measuring process is：
Step 1: speculum 9 is placed in the collimated light path after collimating mirror 3, reflector alignment is adjusted using autocollimation method
Frame 25 makes speculum 9 and collimated light beam coaxial；
Step 2: optical parallel 6 is placed in the collimated light path after collimating mirror 3, optical parallel is adjusted using autocollimation method
Adjustment frame 26 makes optical parallel 6 and collimated light beam coaxial；
Step 3: measured lens 5 is placed in the collimated light path after collimating mirror 3, adjustment measured lens adjustment frame 27 makes measured lens 5
It is coaxial with collimated light beam；
Step 4: controlling speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make measurement light
Beam (16) passes through n=3 secondary reflections between optical parallel (6) and speculum (9), and light beam focuses on optical parallel (6) surface afterwards
(7) opening position.Plane of motion speculum (9), gathered respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information before Jiao, after master control system (20) differential processing such as
Scheme the confocal response curve of system differential shown in (4), accurately determined using the differential confocal response curve zero crossing shown in figure (4)
Light beam convergent point, now the position of speculum 9 is z to record3=-1.2105mm；
Step 5: continuing to control speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make survey
Amount light beam (16) passes through n=4 secondary reflections between optical parallel (6) and speculum (9), and light beam focuses on table before speculum (9)
Face (8) opening position.Plane of motion speculum (9), adopted respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information before collection is burnt, after master control system (20) differential processing
The confocal response curve of system differential as shown in figure (4), it is accurately true using the differential confocal response curve zero crossing shown in figure (4)
Determine light beam convergent point, now the position of speculum 9 is z to record4=470.2507mm；
Step 6: the reflector position information z according to record3And z4, calculate the focal length value of measured lens 5.
This embodiment is realized by a series of measure and the focal length value of long-focus measured lens 5 is measured.In measurement process
In, the focused spot of measured lens 5 is accurately focused using differential confocal measurement method, measurement accuracy is high, and environment resistant is done
It is strong to disturb ability.
Embodiment 2
As shown in Fig. 2 exemplified by measuring n=4 secondary reflections and n=3 secondary reflections successively：
When measured lens 5 use planoconvex spotlight of the bore for D=150mm, its convex radius r=4998.8608mm,
The thickness b=10mm of optical parallel 6 used, refractive index n=1.5146mm, d=is spaced between measured lens 5 and optical parallel 6
During 319.62mm, and plane is used towards collimation light direction, multiple reflections formula laser differential confocal Long focal length measurement device such as Fig. 2 institutes
Show, its measuring process is：
Step 1: speculum 9 is placed in the collimated light path after collimating mirror 3, made using autocollimation method adjustment adjustment frame 25
Speculum 9 and collimated light beam are coaxial；
Step 2: optical parallel 6 is placed in the collimated light path after collimating mirror 3, adjustment frame 26 is adjusted using autocollimation method
Make optical parallel 6 and collimated light beam coaxial；
Step 3: measured lens 5 is placed in the collimated light path after collimating mirror 3, adjustment adjustment frame 27 makes measured lens 5 and collimation
Light beam is coaxial；
Step 4: controlling speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make measurement light
Beam (16) passes through n=4 secondary reflections between optical parallel (6) and speculum (9), and light beam focuses on speculum (9) preceding surface (8)
Opening position.Plane of motion speculum (9), before gathering Jiao respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information, as schemed after master control system (20) differential processing
(4) the confocal response curve of system differential shown in, light is accurately determined using the differential confocal response curve zero crossing shown in figure (4)
Beam convergent point, now the position of speculum 9 is z to record4=470.2197mm；
Step 5: continuing to control speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make survey
Amount light beam (16) passes through n=3 secondary reflections between optical parallel (6) and speculum (9), after light beam focuses on optical parallel (6)
Surface (7) opening position.Plane of motion speculum (9), by image pick-up card before Jiao (21) and defocused image pick-up card (22) difference
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information before collection is burnt, through master control system (20) differential processing
The confocal response curve of system differential as shown in figure (4) afterwards, it is accurate using the differential confocal response curve zero crossing shown in figure (4)
Light beam convergent point is determined, now the position of speculum 9 is z to record3=-1.4623mm；
Step 6: the reflector position information z according to record4And z3, calculate the focal length value of measured lens 5.
Embodiment 3
As shown in figure 3, exemplified by measuring n=5 secondary reflections and n=6 secondary reflections successively：
When measured lens 5 use planoconvex spotlight of the bore for D=150mm, its convex radius r=4998.8608mm,
The thickness b=10mm of optical parallel 6 used, refractive index n=1.5146mm, d=is spaced between measured lens 5 and optical parallel 6
During 319.62mm, and plane is used towards collimation light direction, multiple reflections formula laser differential confocal Long focal length measurement device such as Fig. 3 institutes
Show, its measuring process is：
Step 1: speculum 9 is placed in the collimated light path after collimating mirror 3, made using autocollimation method adjustment adjustment frame 25
Speculum 9 and collimated light beam are coaxial；
Step 2: optical parallel 6 is placed in the collimated light path after collimating mirror 3, adjustment frame 26 is adjusted using autocollimation method
Make optical parallel 6 and collimated light beam coaxial；
Step 3: measured lens 5 is placed in the collimated light path after collimating mirror 3, adjustment adjustment frame 27 makes measured lens 5 and collimation
Light beam is coaxial；
Step 4: controlling speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make measurement light
Beam (16) passes through n=5 secondary reflections between optical parallel (6) and speculum (9), and light beam focuses on optical parallel (6) surface afterwards
(7) opening position.Plane of motion speculum (9), gathered respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information before Jiao, after master control system (20) differential processing such as
Scheme the confocal response curve of system differential shown in (4), accurately determined using the differential confocal response curve zero crossing shown in figure (4)
Light beam convergent point, now the position of speculum 9 is z to record5=1.3035mm；
Step 5: continuing to control speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make survey
Amount light beam (16) passes through n=6 secondary reflections between optical parallel (6) and speculum (9), and light beam focuses on table before speculum (9)
Face (8) opening position.Plane of motion speculum (9), adopted respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information before collection is burnt, after master control system (20) differential processing
The confocal response curve of system differential as shown in figure (4), it is accurately true using the differential confocal response curve zero crossing shown in figure (4)
Determine light beam convergent point, now the position of speculum 9 is z to record6=225.8134mm；
Step 6: the reflector position information z according to record3And z4, calculate the focal length value of measured lens 5.
By above example, laser differential confocal Long focal length measurement method and apparatus of the invention are by multiple reflections
Formula light path folding technology and laser differential confocal focus technology and are combined, and optical path has been greatly shortened, reduce measurement away from
From there is the advantages that measurement accuracy is high, and system architecture is compact, be particularly suitable for the popularization and application in engineering.
The embodiment of the present invention is described above in association with accompanying drawing, but these explanations can not be understood to limit
The scope of the present invention, protection scope of the present invention are limited by appended claims, any in the claims in the present invention base
Change on plinth is all protection scope of the present invention.
Claims (5)
1. multiple reflections formula laser differential confocal Long focal length measurement device, it is characterised in that：Including spot light (1), spectroscope
(2), after collimation lens (3), annular pupil (4), measured lens (5), optical parallel (6), optical parallel before surface (7), speculum
Surface (8), speculum (9), differential confocal detection system (10), wherein differential confocal detection system (10) include light intensity spy before Jiao
Pin hole (12), Amici prism (13), defocused pin hole (14) and defocused light intensity detector (15) before survey device (11), Jiao, it measures light
Lu Wei：Spot light (1) is opened, the light being emitted by spot light (1) forms collimated light beam after spectroscope (2) and collimation lens (3)
And it is radiated on measured lens (5)；Collimated light beam, into measuring beam (16), is somebody's turn to do through measured lens (5) and optical parallel (6) post-concentration
Measuring beam (16) folding mirror between the rear surface (7) of optical parallel (6) and speculum (9) preceding surface (8)；Moved along optical axis
Dynamic speculum (9), when measuring beam (16) convergent point is located at after surface (7) or speculum (9) preceding surface of optical parallel (6)
(8) when nearby, measuring beam (16) is reflected on the rear surface (7) or speculum (9) preceding surface (8) of optical parallel (6), reflection
The light beam returned reversely is reflected into differential confocal detection system through optical parallel (6) and measured lens (5) mirror (2) that is split again
(10), differential confocal detection system (10) will obtain differential confocal Intensity response curve, its zero passage after axial intensity information processing
Point position accurately corresponds to measuring beam (16) convergent point.
2. multiple reflections formula laser differential confocal Long focal length measurement method, it is characterised in that specific measuring process is as follows：
Step 1: speculum (9) is placed in the collimated light path after collimating mirror (3), adjusting speculum (9) using autocollimation method makes
It is coaxial with collimated light beam；
Step 2: optical parallel (6) is placed in the collimated light path after collimating mirror (3), optical parallel is adjusted using autocollimation method
(6) make it coaxial with collimated light beam；
Step 3: measured lens (5) is placed in the collimated light path after collimating mirror (3), adjustment measured lens (5) makes itself and collimated light beam
Coaxially；
Step 4: along optical axis direction mobile mirror (9), make measuring beam (16) between optical parallel (6) and speculum (9)
By n=i secondary reflections, i=0,1,2 ..., light beam focuses on optical parallel (6) surface (7) or speculum (9) preceding surface (8) afterwards
When neighbouring, mobile mirror (9), the confocal Intensity response curve of system differential is measured by differential confocal detection system (10), utilized
Differential confocal response curve zero crossing accurately determines the convergent point of measuring beam (16), and now speculum (9) position is z to recordi；
Step 5: continue optical axis direction mobile mirror (9), make measuring beam (16) optical parallel (6) and speculum (9) it
Between pass through n=j secondary reflections, j=0,1,2 ..., light beam focuses on optical parallel (6) surface (7) or speculum (9) preceding surface afterwards
(8) when near position, mobile mirror (9), it is bent that the confocal Intensity response of system differential is measured by differential confocal detection system (10)
Line, the convergent point of measuring beam (16) is accurately determined using differential confocal response curve zero crossing, record now speculum (9) position
It is set to zj；
Step 6: the reflector position information z according to recordiAnd zj, with reference to optical parallel thickness b, measured lens and optical parallel axle
To interval d and optical parallel refractive index n0Calculate measured lens (5) vertex focal length value；
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<mo>+</mo>
<mi>d</mi>
<mo>+</mo>
<mfrac>
<mn>1</mn>
<msub>
<mi>n</mi>
<mn>0</mn>
</msub>
</mfrac>
<mi>b</mi>
</mrow>
Step 7: the measured lens thickness b further according to known certain margin of tolerance1, refractive index n1, surface curvature radius r11And r12,
By vertex focal length fBFD' conversion obtains tested focal length value f '；
<mrow>
<msup>
<mi>f</mi>
<mo>&prime;</mo>
</msup>
<mo>=</mo>
<msubsup>
<mi>f</mi>
<mrow>
<mi>B</mi>
<mi>F</mi>
<mi>D</mi>
</mrow>
<mo>&prime;</mo>
</msubsup>
<mo>+</mo>
<mfrac>
<mrow>
<msub>
<mi>r</mi>
<mn>12</mn>
</msub>
<msub>
<mi>b</mi>
<mn>1</mn>
</msub>
</mrow>
<mrow>
<msub>
<mi>n</mi>
<mn>1</mn>
</msub>
<mrow>
<mo>(</mo>
<msub>
<mi>r</mi>
<mn>12</mn>
</msub>
<mo>-</mo>
<msub>
<mi>r</mi>
<mn>11</mn>
</msub>
<mo>)</mo>
</mrow>
<mo>+</mo>
<mrow>
<mo>(</mo>
<msub>
<mi>n</mi>
<mn>1</mn>
</msub>
<mo>-</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<msub>
<mi>b</mi>
<mn>1</mn>
</msub>
</mrow>
</mfrac>
<mo>.</mo>
</mrow>
3. multiple reflections formula laser differential confocal Long focal length measurement device according to claim 1, it is characterised in that：Also wrap
Include spot light generating means (17), laser (18), optical fiber (19), master control system (20), it is burnt before image pick-up card (21), defocused
Image pick-up card (22), electromechanical controlling device (23), rectilinear translation guide rail (24), reflector alignment frame (25), optical parallel are adjusted
Whole frame (26), measured lens adjustment frame (27)；Its relation is：The light beam that spot light generating means (17) is sent by laser (18) passes through
Optical fiber (19) output is formed；Image pick-up card (21) and defocused image pick-up card (22) are respectively used to light intensity detection before Jiao before Jiao
The intensity signal that device (11) and defocused light intensity detector (15) collect is transferred to master control system (20) processing and obtains system differential
Confocal Intensity response curve；Reflector alignment frame (25) is located on rectilinear translation guide rail (24), for adjusting speculum (9), puts down
Optical parallel adjustment frame (26) and measured lens adjustment frame (27) are respectively used to adjust optical parallel (6) and measured lens (5).
4. multiple reflections formula laser differential confocal Long focal length measurement device according to claim 3, it is characterised in that：By its
High precision test and optical system focal length value for long focus length of lens value detect, and specific measuring process is as follows：
Step 1: speculum (9) is placed in the collimated light path after collimating mirror (3), reflector alignment is adjusted using autocollimation method
Frame (25) makes speculum (9) and collimated light beam coaxial；
Step 2: optical parallel (6) is placed in the collimated light path after collimating mirror (3), optical parallel is adjusted using autocollimation method
Adjustment frame (26) makes optical parallel (6) and collimated light beam coaxial；
Step 3: measured lens (5) is placed in the collimated light path after collimating mirror (3), adjustment measured lens adjustment frame (27) makes to be tested
Mirror (5) and collimated light beam are coaxial；
Step 4: controlling speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make measuring beam
(16) n=i secondary reflections are passed through between optical parallel (6) and speculum (9), light beam focuses on optical parallel (6) surface (7) afterwards
Opening position, plane of motion speculum (9), before gathering Jiao respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information, obtained through the differential processing of master control system (20) differential
Confocal response curve, light beam convergent point is accurately determined using differential confocal response curve zero crossing, records now speculum (9) position
It is set to zi；
Step 5: continuing to control speculum (9) mobile along rectilinear translation guide rail (24) by electromechanical controlling device (23), make measurement light
Beam (16) passes through n=j secondary reflections between optical parallel (6) and speculum (9), and light beam focuses on optical parallel (6) surface afterwards
(7) opening position, plane of motion speculum (9), gathered respectively by image pick-up card before Jiao (21) and defocused image pick-up card (22)
Light intensity detector (11) and defocused light intensity detector (15) axial intensity information before Jiao, obtained through the differential processing of master control system (20)
The confocal response curve of system differential, light beam convergent point is accurately determined using differential confocal response curve zero crossing, is recorded now anti-
It is z to penetrate mirror (9) positionj；
Step 6: the reflector position information z according to recordiAnd zj, with reference to optical parallel thickness b, measured lens and optical parallel axle
To interval d and optical parallel refractive index n0Calculate measured lens (5) vertex focal length value；
<mrow>
<msubsup>
<mi>f</mi>
<mrow>
<mi>B</mi>
<mi>F</mi>
<mi>D</mi>
</mrow>
<mo>&prime;</mo>
</msubsup>
<mo>=</mo>
<mfrac>
<mrow>
<mo>(</mo>
<mi>i</mi>
<mo>+</mo>
<mn>1</mn>
<mo>)</mo>
<mo>(</mo>
<mi>j</mi>
<mo>+</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<mrow>
<mi>j</mi>
<mo>-</mo>
<mi>i</mi>
</mrow>
</mfrac>
<mrow>
<mo>(</mo>
<msub>
<mi>z</mi>
<mi>j</mi>
</msub>
<mo>-</mo>
<msub>
<mi>z</mi>
<mi>i</mi>
</msub>
<mo>)</mo>
</mrow>
<mo>+</mo>
<mi>d</mi>
<mo>+</mo>
<mfrac>
<mn>1</mn>
<msub>
<mi>n</mi>
<mn>0</mn>
</msub>
</mfrac>
<mi>b</mi>
</mrow>
Step 7: the measured lens thickness b further according to known certain margin of tolerance1, refractive index n1, surface curvature radius r11And r12,
By vertex focal length fBFD' conversion obtains tested focal length value f '；
<mrow>
<msup>
<mi>f</mi>
<mo>&prime;</mo>
</msup>
<mo>=</mo>
<msubsup>
<mi>f</mi>
<mrow>
<mi>B</mi>
<mi>F</mi>
<mi>D</mi>
</mrow>
<mo>&prime;</mo>
</msubsup>
<mo>+</mo>
<mfrac>
<mrow>
<msub>
<mi>r</mi>
<mn>12</mn>
</msub>
<msub>
<mi>b</mi>
<mn>1</mn>
</msub>
</mrow>
<mrow>
<msub>
<mi>n</mi>
<mn>1</mn>
</msub>
<mrow>
<mo>(</mo>
<msub>
<mi>r</mi>
<mn>12</mn>
</msub>
<mo>-</mo>
<msub>
<mi>r</mi>
<mn>11</mn>
</msub>
<mo>)</mo>
</mrow>
<mo>+</mo>
<mrow>
<mo>(</mo>
<msub>
<mi>n</mi>
<mn>1</mn>
</msub>
<mo>-</mo>
<mn>1</mn>
<mo>)</mo>
</mrow>
<msub>
<mi>b</mi>
<mn>1</mn>
</msub>
</mrow>
</mfrac>
<mo>.</mo>
</mrow>
5. multiple reflections formula laser differential confocal Long focal length measurement method according to claim 2, it is characterised in that：In light
Increase annular pupil in road to be modulated measuring beam, form annular beam, wave aberration is to measuring beam when reduction focuses
Influence, improve measurement accuracy.
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| CN107584337A (en) * | 2017-10-23 | 2018-01-16 | 北京理工大学 | Based on the spherical optics element of confocal laser interferometry without model processing method |
| CN109540474B (en) * | 2018-11-13 | 2020-06-05 | 北京理工大学 | Rear-mounted pupil laser differential confocal focal length measuring method and device |
| CN110044415B (en) * | 2019-04-19 | 2020-12-11 | 北京理工大学 | Multi-parameter measuring method and device for dislocation differential confocal interference element |
| CN110044414B (en) * | 2019-04-19 | 2020-12-11 | 北京理工大学 | Transverse subtraction differential confocal interference element multi-parameter measurement method and device |
| CN109990984B (en) * | 2019-04-19 | 2021-02-26 | 北京理工大学 | Transverse subtraction differential confocal super-long focal length measuring method |
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| CN101408478B (en) * | 2008-11-21 | 2010-07-07 | 北京理工大学 | Method and apparatus for measuring cofocal combined ultra-long focal distance |
| CN102589853B (en) * | 2012-01-16 | 2014-01-08 | 北京理工大学 | Focal length measuring method of auto-collimating differential confocal lens |
| CN102589851B (en) * | 2012-01-16 | 2014-01-08 | 北京理工大学 | Method for measuring focal length of reflection type confocal lens |
| CN102589854B (en) * | 2012-01-16 | 2014-01-08 | 北京理工大学 | Method for measuring focal length of reflection type differential confocal lens |
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