CN201152808Y - Lens focal length measurement mechanism - Google Patents
Lens focal length measurement mechanism Download PDFInfo
- Publication number
- CN201152808Y CN201152808Y CNU2007200745575U CN200720074557U CN201152808Y CN 201152808 Y CN201152808 Y CN 201152808Y CN U2007200745575 U CNU2007200745575 U CN U2007200745575U CN 200720074557 U CN200720074557 U CN 200720074557U CN 201152808 Y CN201152808 Y CN 201152808Y
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- lens
- measured
- pointolite
- focal length
- knife
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- Length Measuring Devices By Optical Means (AREA)
Abstract
The utility model discloses a lens focal length measuring device which has the structure that a plane mirror and a lens to be measured are vertically arranged on a platform; a pointolite, a vertical knife edge, a ranging laser and a CCD detector are all fixed on an optical adjustable mount, the optical adjustable mount is arranged on a one-dimensional precisely-translational guide rail, the one-dimensional precisely-translational guide rail is arranged along the main shaft of the lens to be measured and on the lower side of the focus point thereof, the measured zero point of the pointolite, the vertical knife edge and the ranging laser are arranged on the same plane which is perpendicular to the main shaft of the lens to be measured, the divergent light of the pointolite becomes a convergent beam after the transmission and the reflection of the lens to be measured and the plane mirror, the image is received by the CCD detector near the vertical knife edge, the output end of the CCD detector is connected with a displayer, and the divergent light beam of the ranging laser points to the geometrical main surface of the lens to be measured. The device is applicable to the measurement of lens with small caliber and short focal length and lens with large caliber and long focal length.
Description
Technical field
The utility model relates to lens, particularly a kind of measurement mechanism of the focal length of lens.
Background technology
Along with developing rapidly of large laser nuclear fusion device (ICF), the space filter lens bore of using in this device is big 0.3～0.5 meter, long tens meters of focal length.And existing large-aperture long-focus lens processing and measuring accuracy only are 1～5 ‰, long-focus nominal measure error based on the rich tower effect of Ronchi grating tal fibre is 0.15%, but this method mechanism complexity, optical element is many, measurement result is subjected to the influence of calibrated error, is not suitable for heavy caliber, big F counts the demand that optical element is measured.Spatial filter is limited by the lens in-process measurement, and the adjusting mechanism complex structure is debug difficult in maintenance, therefore need the high-precision large-aperture long-focus lens measurement method of development, realize the high-acruracy survey of the focal length of lens, simplify lens adjusting mechanism and regulative mode is installed, improve mechanism stability.
Summary of the invention
The purpose of this utility model is to overcome the difficulty of above-mentioned prior art, and a kind of measurement mechanism of the focal length of lens is provided, and this device can be used for heavy caliber, the big lens (being designated hereinafter simply as lens to be measured) that the F number is high-accuracy after machining carry out the measurement of the focal length of lens.This device more can be used for the measurement and the assessment of small-bore short focal length and large-aperture long-focus lens, should have advantage directly perceived accurate, focometry precision height, and mechanism is simple, debugs measurement in the time of also can realizing in the optical instrument lens high-precision real, satisfies engineering demand.
Technical solution of the present utility model is as follows:
A kind of measurement mechanism of the focal length of lens, its formation comprises: plane mirror, lens to be measured, pointolite, the vertical edge of a knife, the accurate translation guide rail of one dimension, laser range finder, ccd detector and display, its position relation is as follows: plane mirror and lens to be measured are installed on the platform vertically, pointolite, the vertical edge of a knife, laser range finder and ccd detector all are fixed on the optical adjusting frame, this optical adjusting frame is installed in again on the accurate translation guide rail of described one dimension, the accurate translation guide rail of this one dimension is provided with along described lens main axis direction to be measured and below its focus, the moving direction of the accurate translation guide rail of this one dimension is parallel with lens main axis to be measured, described pointolite, vertically the measurement of the edge of a knife and laser range finder guarantee zero point with the perpendicular same plane of the main shaft of lens to be measured in, and the described vertical edge of a knife can be done left and right sides translation adjustment with respect to pointolite, the diverging light of this pointolite becomes convergent beam behind lens to be measured and plane mirror saturating anti-, be imaged near the vertical edge of a knife, and should receive by described ccd detector by picture, the output terminal of this ccd detector links to each other with described display, how much interareas of the described lens to be measured of emission beam-pointing of described laser range finder; Described plane mirror requires to have the bidimensional angle-adjusting mechanism.
Being positioned near the focus of the described lens to be measured pointolite and the distance of saturating anti-convergent beam is 2mm～10mm.
Utilize the measurement mechanism of the described focal length of lens to carry out the measuring method of the focal length of lens, it is characterized in that comprising the following steps:
1. at first lens to be measured and plane mirror are installed on the optical table vertically point of adjustment light source and lens autocollimation to be measured;
2. regulating plane mirror makes the convergent beam that reflects through this plane mirror enter described ccd detector;
3. measure the depth of focus of lens to be measured:
Move described optical adjusting frame along the major axes orientation of lens to be measured on the accurate translation guide rail of one dimension, i.e. transfer point light source, the vertically edge of a knife and laser range finder, and observe hot spot in display move pointolite and opposite from burnt forward direction is defocused again,
When pointolite is before burnt, through beam divergence behind the lens to be measured, after the plane reflection mirror reflection, point-sourcre imaging is at the rear of the vertical edge of a knife, the vertical edge of a knife of move left and right, it is opposite with vertical edge of a knife moving direction to observe hot spot deepening direction by ccd detector in display, is burnt preceding the variation, before this moment, the pointolite and the vertical edge of a knife were positioned at focus, should move backward;
When pointolite when defocused, through beam convergence behind the lens to be measured, by point-sourcre imaging after the plane reflection mirror reflection in vertical edge of a knife the place ahead, the vertical edge of a knife of move left and right, in display, observe hot spot deepening direction and vertically edge of a knife moving direction is identical by ccd detector, be defocused variation, after this moment, the pointolite and the edge of a knife were positioned at focus, should move forward.
When pointolite during at focal depth range, the vertical edge of a knife of move left and right is observed the instantaneous deepening of hot spot by ccd detector in display, do not have gradual process to be focal plane and change.
In display, observe pointolite and vertical edge of a knife front and back distance between two points that focal plane changes, be depth of focus z;
4. the pointolite and the vertical edge of a knife are moved to the midpoint of depth of focus, with the distance L of laser range finder measurement point light source to how much interareas of lens to be measured;
5. calculated the focal length of lens to be measured according to lens how much interareas and optics principal plane by following formula apart from d again: f=L+d, this d are determined by optical design, or use other optical method for measuring.
Utilize the measurement mechanism of said lens focal length to carry out the method for optics of lens quality qualitative evaluation, comprise the following steps:
1. the filtering hole of three times of diffraction limits alternatively is set in the position of the described vertical edge of a knife, moving described adjustment rack on the accurate translation guide rail of one dimension makes pointolite and described opening diffracting arrive the focal plane of lens to be measured, finely tune described plane mirror and make reflecting light beam, and between described filtering hole and ccd detector, insert second lens by described filtering hole;
2. use the described filtering of light illumination hole at the rear side edge in described filtering hole, the focal spot that makes lens to be measured through filtering hole and second lens imaging on the ccd detector face, observe the far-field focus shape at display, assess the optics crudy of lens to be measured according to focal spot qualitatively:
When the lens spherical aberration correction was not enough, burnt preceding different with defocused focal spot diffraction image: the diffraction image before burnt had the ring of light bright and sharp, clear-cut, all blurs at defocused all rings of light, and the focused spot diameter on focal plane is greater than ideal value;
Astigmatism is that the place is cruciform at depth of focus because optical element causes that the focal spot diffraction image is ovalize before and after focus when inaccurate or element surface has irregular face shape error to inclined light shaft, in fixed;
Coma is owing to cause from axle, focal spot diffraction image luminous energy skewness, and the brightness and the width of same diffraction ring are inhomogeneous, and luminous energy distributes and bright head occurs, at the diffraction ring of the residual fracture of a side.
Technique effect of the present utility model is as follows:
1, the utility model can the precision measurement focal length of lens and depth of focus.The ideal point light source is positioned near lens theoretical focal point and the same plane vertical with the lens main shaft with the edge of a knife, the diverging light of pointolite is imaged near the edge of a knife through lens and catoptron are counter thoroughly, the pointolite and the edge of a knife are jointly along the lens main axle moving, edge of a knife cutting folded light beam, determine focal plane position and depth of focus by observing burnt preceding defocused variation, accurately measure the distance of how much interareas of focal plane and lens, converse focal length.
2, the utility model can be differentiated the optics of lens crudy, after adopting anti-method to determine focal plane position, the light that ideal point light source in the focal plane sends forms the profusely desirable directional light in footpath behind lens, the whole machined surface shape information that has comprised lens in the far-field spot through plane reflection mirror reflection post-concentration can be judged lens crudy level according to the information of focal spot.
Description of drawings
Fig. 1 is the structural representation of the utility model focal length of lens measurement mechanism
Fig. 2 is the structural scheme of mechanism of the utility model optics of lens quality discrimination
Embodiment
See also Fig. 1 earlier, Fig. 1 is the structural representation of focal length of lens measurement mechanism of the present utility model, as seen from the figure, the measurement mechanism of the utility model focal length of lens, characteristics are that its formation comprises: plane mirror 5, lens 4 to be measured, pointolite 1, the vertical edge of a knife 2, the accurate translation guide rail 3 of one dimension, laser range finder 6, ccd detector 7 and display 8, its position relation is as follows: plane mirror 5 and lens to be measured 4 are installed on the platform vertically, pointolite 1, the vertical edge of a knife 2, laser range finder 6 and ccd detector 7 all are fixed on the optical adjusting frame, this optical adjusting frame is installed in again on the accurate translation guide rail 3 of described one dimension, the accurate translation guide rail 3 of this one dimension is provided with along described lens 4 main axis directions to be measured and below its focus, the moving direction of the accurate translation guide rail 3 of this one dimension is parallel with lens 4 main axiss to be measured, described pointolite 1, vertically the measurement of the edge of a knife 2 and laser range finder 6 guarantee zero point with the perpendicular same plane of the main shaft of lens 4 to be measured in, and the described vertical edge of a knife 2 can be done left and right sides translation adjustment with respect to pointolite 1, the diverging light of this pointolite 1 becomes convergent beam behind lens 4 to be measured and plane mirror 5 saturating anti-, be imaged near the vertical edge of a knife 2, and should receive by described ccd detector 7 by picture, the output terminal of this ccd detector 7 links to each other with described display 8, how much interareas of the described lens 4 to be measured of emission beam-pointing of described laser range finder 6; Described plane mirror 5 requires to have the bidimensional angle-adjusting mechanism.
Near the focus of described lens to be measured 4 the pointolite 1 and the distance of saturating anti-convergent beam should be as far as possible little, be as the criterion not produce serious off-axis astigmatism, with the distance of saturating anti-convergent beam be 2mm～10mm.
Utilize the measurement mechanism of the described focal length of lens to carry out the measuring method of the focal length of lens, comprise the following steps:
1. at first lens 4 to be measured and plane mirror 5 are installed on the optical table vertically point of adjustment light source 1 and lens 4 autocollimations to be measured;
2. regulating plane mirror 5 makes the convergent beam that reflects through plane mirror 5 enter described ccd detector 7;
3. measure the depth of focus of lens 4 to be measured:
Major axes orientation along lens 4 to be measured moves described optical adjusting frame on the accurate translation guide rail 3 of one dimension, be transfer point light source 1, the vertical edge of a knife 2 and laser range finder 6, and in display 8, observe hot spot, again that pointolite 1 is defocused mobile from burnt forward direction, in display 8, observe pointolite 1 and the vertical edge of a knife 2 front and back distance between two points that focal plane changes, be depth of focus z;
4. the pointolite 1 and the vertical edge of a knife 2 are moved to the midpoint of depth of focus, with the distance L of laser range finder 6 measurement point light sources 1 to how much interareas of lens 4 to be measured;
5. calculated the focal length of lens 4 to be measured according to lens how much interareas and optics principal plane by following formula apart from d again: f=L+d, this d are determined by optical design, or use other optical method for measuring.
Consult Fig. 2, Fig. 2 is the structural scheme of mechanism of the utility model optics of lens quality discrimination.The method of the utility model optics of lens quality qualitative evaluation comprises the following steps:
1. the filtering hole 9 of three times of diffraction limits is set in the position of the described vertical edge of a knife 2, moving described adjustment rack on the accurate translation guide rail 3 of one dimension makes pointolite 1 and described opening diffracting 9 arrive the focal plane of lens 4 to be measured, finely tune described plane mirror 5 and make reflecting light beam, and between described filtering hole 9 and ccd detector 7, insert second lens 11 by described filtering hole 9;
2. use the described filtering of light source 10 illuminations hole 9 at the rear side edge in described filtering hole 9, the focal spot that makes lens 4 to be measured is on filtering hole 9 and second lens 11 are imaged on 7 of ccd detectors, observe the far-field focus shape at display 8, assess the optics crudy of lens 4 to be measured according to focal spot qualitatively:
When the lens spherical aberration correction was not enough, burnt preceding different with defocused focal spot diffraction image: the diffraction image before burnt had the ring of light bright and sharp, clear-cut, all blurs at defocused all rings of light, and the focused spot diameter on focal plane is greater than ideal value;
Astigmatism is that the place is cruciform at depth of focus because optical element causes that the focal spot diffraction image is ovalize before and after focus when inaccurate or element surface has irregular face shape error to inclined light shaft, in fixed;
Coma is owing to cause from axle, focal spot diffraction image luminous energy skewness, and the brightness and the width of same diffraction ring are inhomogeneous, and luminous energy distributes and bright head occurs, at the diffraction ring of the residual fracture of a side.
The output lens that the utility model is used for refreshing light II superlaser (the nine tunnel) spatial filter SF8 is measured.
The design focal length of lens to be measured is 9328mm, and the clear aperture of lens to be measured is φ 300mm in the measuring process, and the ideal point light source adopts the single transverse mode fiber optic point source of wavelength X=1.053 μ m.The divergent beams of pointolite are Gauss's focused beam after saturating anti-, and the burnt spot radius of convergence is:
W
0＝λf′/D＝1.053×10
-6×9.328/0.3＝3.2×10
-5m
Theoretical depth of focus:
Actual measured results is: can obviously differentiate discharge of the coke preceding and defocused variation in the 3mm scope, very approaching with theoretical depth of focus 2.8mm, the focal plane position degree of regulation is less than 0.5mm.The distance of focal plane and lens interarea is measured with the high-precision laser range-finding instrument, measuring error is equal to the precision of laser range finder, adopt Switzerland's Lycra precision distance measurement instrument, ranging 0.2m to 200m, precision reaches ± 1.5mm, resolution is 1mm, and the measurement focal plane is 9317mm to the distance of lens interarea, concerns that according to focal length and intercept conversing focal distance f is 9315mm.
In sum, saturating anti-method focometry precision 3.5mm.At the experiment in SF8 output lens focometry precision less than 3.5/9315=0.37 ‰.And convergent beam is at the depth of focus place, be collimated light beam at Rayleigh scope inner light beam promptly, the filtering aperture can be realized filter function in focal depth range, and saturating anti-method determines that depth of focus length is greater than 2.5mm, the site error of filtering aperture is 1mm in the engineering construction, satisfies requirement of engineering.
The measurement of the utility model focal length of lens has accurate advantage directly perceived, is applicable to simultaneously small-bore Short focal length and large-aperture long-focus lens, focometry can reach 3/10000ths magnitudes, and regulates smart Degree is high, and the depth of focus error is little, and is simple in structure. The optical element that the utility model patent is used only has height Precision reference speculum, surface figure accuracy are the sixth of He-Ne optical maser wavelength. When spot light inclined to one side During the out of focus plane, the reflex of plane mirror makes the relative moving speed of the vertical edge of a knife and picture point Double, certainty of measurement is the twice of common knife. Determine to pass through to observe focal spot behind the focal plane Shape can be judged the face shape error of lens. The utility model patent principle is simple, practical, has Very high use value.
Claims (2)
1, a kind of measurement mechanism of the focal length of lens, be characterised in that its formation comprises: plane mirror (5), lens to be measured (4), pointolite (1), the vertical edge of a knife (2), the accurate translation guide rail (3) of one dimension, laser range finder (6), ccd detector (7) and display (8), its position relation is as follows: plane mirror (5) and lens to be measured (4) are installed on the platform vertically, pointolite (1), the vertical edge of a knife (2), laser range finder (6) and ccd detector (7) all are fixed on the optical adjusting frame, this adjustment rack is installed on the accurate translation guide rail of described one dimension (3), the accurate translation guide rail of this one dimension (3) is provided with along described lens to be measured (4) main axis direction and below its focus, the moving direction of the accurate translation guide rail of this one dimension (3) is parallel with lens to be measured (4) main axis, described pointolite (1), vertically the measurement of the edge of a knife (2) and laser range finder (6) guarantee zero point with the perpendicular same plane of the main shaft of lens to be measured (4) in, and the described vertical edge of a knife (2) can be done left and right sides translation adjustment with respect to pointolite (1), the output terminal of this ccd detector (7) links to each other with described display (8), how much interareas of the described lens to be measured of the emission beam-pointing of described laser range finder (6) (4); Described plane mirror (5) requires to have the bidimensional angle-adjusting mechanism.
2, the measurement mechanism of the focal length of lens according to claim 1, the distance that it is characterized in that being positioned at described pointolite (1) and saturating anti-convergent beam is 2mm～10mm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200745575U CN201152808Y (en) | 2007-09-11 | 2007-09-11 | Lens focal length measurement mechanism |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200745575U CN201152808Y (en) | 2007-09-11 | 2007-09-11 | Lens focal length measurement mechanism |
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| CN201152808Y true CN201152808Y (en) | 2008-11-19 |
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| CNU2007200745575U Expired - Fee Related CN201152808Y (en) | 2007-09-11 | 2007-09-11 | Lens focal length measurement mechanism |
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Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102564736A (en) * | 2011-09-15 | 2012-07-11 | 北京国科世纪激光技术有限公司 | Device and method for measuring focal length of lens |
| CN102608771A (en) * | 2012-03-16 | 2012-07-25 | 中国科学院上海光学精密机械研究所 | Simulated light-spot light source for high-power laser system |
| CN102998096A (en) * | 2012-12-17 | 2013-03-27 | 吉林大学 | Method for measuring focal distance of convex lens |
| CN103439088A (en) * | 2013-08-19 | 2013-12-11 | 江苏大学 | Method and device for using convex lens to generate collimated light |
| CN104165758A (en) * | 2014-08-29 | 2014-11-26 | 南京理工大学 | Lens focal length measuring device and method based on Fizeau interferomenter |
| CN106556461A (en) * | 2016-12-08 | 2017-04-05 | 中国科学院光电技术研究所 | A kind of optical spectrum imaging device based on adaptive optics |
| CN109459214A (en) * | 2018-11-08 | 2019-03-12 | 中国航空制造技术研究院 | A kind of focal length of convex lens measurement method and device |
| CN114486186A (en) * | 2021-12-27 | 2022-05-13 | 歌尔股份有限公司 | Detection device and method for effective focal length of lens |
-
2007
- 2007-09-11 CN CNU2007200745575U patent/CN201152808Y/en not_active Expired - Fee Related
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102564736A (en) * | 2011-09-15 | 2012-07-11 | 北京国科世纪激光技术有限公司 | Device and method for measuring focal length of lens |
| CN102608771A (en) * | 2012-03-16 | 2012-07-25 | 中国科学院上海光学精密机械研究所 | Simulated light-spot light source for high-power laser system |
| CN102608771B (en) * | 2012-03-16 | 2013-12-25 | 中国科学院上海光学精密机械研究所 | Simulated light-spot light source for high-power laser system |
| CN102998096A (en) * | 2012-12-17 | 2013-03-27 | 吉林大学 | Method for measuring focal distance of convex lens |
| CN102998096B (en) * | 2012-12-17 | 2016-03-30 | 吉林大学 | The measuring method of focal length of convex lens |
| CN103439088A (en) * | 2013-08-19 | 2013-12-11 | 江苏大学 | Method and device for using convex lens to generate collimated light |
| CN103439088B (en) * | 2013-08-19 | 2015-09-30 | 江苏大学 | The method and apparatus of directional light is produced with convex lens |
| CN104165758A (en) * | 2014-08-29 | 2014-11-26 | 南京理工大学 | Lens focal length measuring device and method based on Fizeau interferomenter |
| CN106556461A (en) * | 2016-12-08 | 2017-04-05 | 中国科学院光电技术研究所 | A kind of optical spectrum imaging device based on adaptive optics |
| CN106556461B (en) * | 2016-12-08 | 2018-04-06 | 中国科学院光电技术研究所 | A kind of optical spectrum imaging device based on adaptive optics |
| CN109459214A (en) * | 2018-11-08 | 2019-03-12 | 中国航空制造技术研究院 | A kind of focal length of convex lens measurement method and device |
| CN114486186A (en) * | 2021-12-27 | 2022-05-13 | 歌尔股份有限公司 | Detection device and method for effective focal length of lens |
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Legal Events
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| C17 | Cessation of patent right | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20081119 |