CN102313642B - High-precision focus detection device for long-focus lens - Google Patents
High-precision focus detection device for long-focus lens Download PDFInfo
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- CN102313642B CN102313642B CN 201110252061 CN201110252061A CN102313642B CN 102313642 B CN102313642 B CN 102313642B CN 201110252061 CN201110252061 CN 201110252061 CN 201110252061 A CN201110252061 A CN 201110252061A CN 102313642 B CN102313642 B CN 102313642B
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Abstract
The invention discloses a high-precision focus detection device for a long-focus lens, which comprises a laser, a microscope objective, a pin hole, a first Ronchi grating, the long-focus lens to be detected, a second Ronchi grating, ground glass and a CCD (Charge Coupled Device) camera. Light emitted by the laser passes through the microscope objective and the pin hole to form a divergent beam and the divergent beam enters the first Ronchi grating and then passes through the long-focus lens to be detected and the second Ronchi grating; the second Ronchi grating is placed at a certain talbot-order position of the first Ronchi grating, so that Moire fringes can be formed on a talbot image of the first Ronchi grating and the second Ronchi grating; and the fringes are acquired by the CCD camera and the focus of the lens to be detected can be obtained by calculating angles of the fringes. The high-precision focus detection device has a simple structure, is easy to implement, has high precision, can be used for detecting the long-focus lens and accurately measuring the focus in an optical system and particularly can be used for accurately measuring the focus of the large-caliber long-focus lens (the focus is in the range of meters and dozens of meters), so that an error caused by the scanning detection is avoided.
Description
Technical field
The invention belongs to the optic test field, relate in particular to a kind of focal length pick-up unit of high precision long-focus lens.
Background technology
In optics, astronomy and the field such as military, long-focus lens is very crucial basic components, is bringing into play more and more important effect, and required focal length is more and more longer, and bore is also increasing.In large scale system, such as national portfire, long-focus lens is crucial collective optics, and the focal length of these lens reaches 40 meters.The use of long-focus lens needs corresponding detection technique, but at present high precision detect particularly be accurate to several millimeters even the measurement of hundreds of micron still have a lot of difficulties, for example spherometer can Measurement accuracy to 2 meter, precision has ten thousand/, but along with the increase of focal length, utilize spherometer to detect with regard to indeterminacy.In addition, high-precision detection be subject to external interference particularly the impact of air turbulence and external shock be difficult to eliminate, and in detection system, the aberration of light path own also increases along with the measurement impact of the increase focusing position of focal length, is difficult to realize high-acruracy survey.Therefore the high precision Long focal length measurement method and apparatus that is easy to realize has very large application space and very important application.
Summary of the invention
The objective of the invention is for the deficiencies in the prior art, a kind of focal length pick-up unit of high precision long-focus lens is provided.
The focal length pick-up unit of high precision long-focus lens comprises laser instrument, microcobjective, pin hole, the first Ronchi grating, long-focus lens to be measured, the second Ronchi grating, frosted glass, CCD camera; The light that laser instrument sends forms divergent beams after microcobjective and pin hole, incide on the first Ronchi grating, again through long-focus lens to be measured and the second Ronchi grating, the Taibo picture of the first Ronchi grating and the second Ronchi grating can form Moire fringe so, with CCD collected by camera striped, calculate the Moire fringe angle and just can obtain the focal length of lens to be measured.
The periodicity linear gratings of described the first Ronchi grating and the second Ronchi grating even structure, the cycle is 350～500 microns.Described the second Ronchi grating is placed on the talbot distance d of the first Ronchi grating, wherein
,
Positive integer,
The grating cycle of the first Ronchi grating,
It is the light wavelength that laser instrument sends.Described the second Ronchi grating and frosted glass all are placed on the guide rail that can move along optical axis direction, guide precision 0.1mm.
The invention has the beneficial effects as follows:
The present invention directly the aperture outgoing disperse light path in detect, the collimator and extender that need not to carry out in a lot of other detection systems of picture multilayer obtains the heavy caliber light beam, simple in structure being easy to realized.Utilize Tabo effect and Moire fringe technology, the technology of this diffractometry has higher precision than existing interferometry, can realize the high-acruracy survey of long-focus lens and optical system focal length
2. the present invention is 350～500 microns at two Ronchi grating cycles of using, and the cycle is large, and the coherent measurement with the conventional interference technology of comparing is insensitive for the factors such as disturbance of outside air;
3. the present invention can be for detection of the focal range of several meters to tens meters, the second Ronchi grating can be accurate mobile along optical axis, when measuring the different focal lens, only need mobile the second Ronchi grating to reach suitable position, focal length measurement and high repeatability precision is arranged accurately just, light path simply is easy to realize.
Description of drawings
Fig. 1 is the focal length structure of the detecting device schematic diagram of high precision long-focus lens.
Embodiment
Principle of work of the present invention: the light that laser instrument sends forms divergent beams after microcobjective and pin hole, incide on the first Ronchi grating, again through long-focus lens to be measured and the second Ronchi grating, the second Ronchi grating is placed on a certain Taibo level time position of the first Ronchi grating, the Taibo picture of the first Ronchi grating and the second Ronchi grating can form Moire fringe so, with CCD collected by camera striped, calculate the Moire fringe angle and just can obtain the focal length of lens to be measured.Before putting into measured lens, first first and second Ronchi grating is placed in place, measure the focal length value f of the divergent beams that incide the first Ronchi grating place this moment according to the Moire fringe of this moment
1Put into measured lens, suitable movement the second Ronchi grating records focal length value f
2, f
2Be the combined focal length value of divergent beams and lens to be measured in fact, just can obtain like this focal length value f of lens to be measured according to compound lens focal length reduction formula.
As shown in Figure 1, the focal length pick-up unit of a kind of high precision long-focus lens of the present invention comprises laser instrument 1, microcobjective 2, pin hole 3, the first Ronchi grating 4, long-focus lens to be measured 5, the second Ronchi grating 6, frosted glass 7, CCD camera 8; The light that laser instrument 1 sends forms divergent beams after microcobjective 2 and pin hole 3, incide on the first Ronchi grating 4, again through long-focus lens 5 to be measured and the second Ronchi grating 6, the second Ronchi grating 6 is placed on a certain Taibo level time position of the first Ronchi grating 4, the Taibo picture of the first Ronchi grating 4 and 6 of the second Ronchi gratings can form Moire fringe so, gather striped with CCD camera 8, calculate the Moire fringe angle and just can obtain the focal length of lens to be measured.
The periodicity linear gratings of above-mentioned the first Ronchi grating 4 and the second Ronchi grating 6 even structure, the cycle is 350～500 microns.Described the second Ronchi grating 6 is placed on the talbot distance d of the first Ronchi grating 4, wherein
,
Positive integer,
The grating cycle of the first Ronchi grating 4,
It is the light wavelength that laser instrument 1 sends.Described the second Ronchi grating 6, frosted glass 7 and CCD camera 8 all are placed on the guide rail that can move along optical axis direction, guide precision 0.1mm.
Claims (1)
1. the focal length pick-up unit of a high precision long-focus lens, is characterized in that being included in laser instrument (1), microcobjective (2), pin hole (3), the first Ronchi grating (4), long-focus lens to be measured (5), the second Ronchi grating (6), frosted glass (7), the CCD camera (8) placed in turn on same optical axis; The light that laser instrument (1) sends forms divergent beams after microcobjective (2) and pin hole (3), incide on the first Ronchi grating (4), again through long-focus lens to be measured (5) and the second Ronchi grating (6), the Taibo picture of the first Ronchi grating (4) and the second Ronchi grating (6) can form Moire fringe so, gather striped with CCD camera (8), calculate the Moire fringe angle and just can obtain the focal length of lens to be measured;
Described the first Ronchi grating (4) and the second Ronchi grating (6) structure are uniform periodically linear gratings, and the grating cycle is 350～500 microns;
Described the second Ronchi grating (6) is placed on the talbot distance d of the first Ronchi grating (4), wherein
,
Positive integer,
The grating cycle of the first Ronchi grating (4),
It is the light wavelength that laser instrument (1) sends;
Described the second Ronchi grating (6), frosted glass (7) and CCD camera (8) all are placed on the guide rail that can move along same optical axis direction, guide precision 0.1mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201110252061 CN102313642B (en) | 2011-08-30 | 2011-08-30 | High-precision focus detection device for long-focus lens |
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| Application Number | Priority Date | Filing Date | Title |
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| CN 201110252061 CN102313642B (en) | 2011-08-30 | 2011-08-30 | High-precision focus detection device for long-focus lens |
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| CN102313642A CN102313642A (en) | 2012-01-11 |
| CN102313642B true CN102313642B (en) | 2013-06-05 |
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Cited By (1)
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| WO2016181206A1 (en) * | 2015-05-08 | 2016-11-17 | Uniwersytet Warszawski | The measurement setup for determining position of focal plane and effective focal length of an optical system and the method of determining position of focal plane and effective focal length of an optical system |
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| CN102788683B (en) * | 2012-08-31 | 2015-04-22 | 中国科学院光电技术研究所 | Measuring method for micro-lens array focal length based on Newton method and Talbot effect |
| CN103033344B (en) * | 2012-12-14 | 2015-02-18 | 中国科学院长春光学精密机械与物理研究所 | Optical system focal distance detection method |
| CN103063414B (en) * | 2012-12-24 | 2015-06-24 | 南京理工大学 | Focal length measuring device adopting symmetrical grating |
| CN103063413B (en) * | 2012-12-24 | 2015-06-24 | 南京理工大学 | Integrated long-focus measuring device based on Talbot-moire technology |
| CN103063415B (en) * | 2013-01-05 | 2015-09-02 | 浙江大学 | A kind of long focus length of lens measuring method based on Moire fringe coupling |
| CN104515671B (en) * | 2014-12-17 | 2017-02-22 | 中国科学院长春光学精密机械与物理研究所 | Method for precisely measuring focal distance of superlong-focal-distance space camera |
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| CN107515103B (en) * | 2016-06-17 | 2019-06-21 | 南京理工大学 | A kind of focal length detection device and method using circular grating |
| CN107121095B (en) * | 2017-06-08 | 2019-10-18 | 杭州电子科技大学 | A kind of method and device of precise measurement super-large curvature radius |
| CN107588741B (en) * | 2017-09-19 | 2020-01-21 | 深圳大学 | Method and system for measuring camera depth change based on moire fringes |
| CN107782535A (en) * | 2017-10-25 | 2018-03-09 | 福建师范大学 | A kind of focal length of convex lens measurement apparatus and its method |
| CN107941473A (en) * | 2017-12-06 | 2018-04-20 | 西南技术物理研究所 | A kind of Long focal length measurement device with fringe contrast automatic regulation function |
| CN110646171B (en) * | 2019-10-31 | 2021-11-02 | 中国科学院长春光学精密机械与物理研究所 | Method for measuring parallelism of light source |
| CN114061910B (en) * | 2021-11-12 | 2023-06-20 | 西安交通大学 | Device and method for measuring focal length of convex-concave lens |
| US11821755B1 (en) * | 2023-07-19 | 2023-11-21 | Mloptic Corp. | Moiré-based distance measurement method |
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| JPH0276132A (en) * | 1988-09-12 | 1990-03-15 | Minolta Camera Co Ltd | Automatic focusing device |
| US7230722B2 (en) * | 2005-10-19 | 2007-06-12 | University Of Maryland | Shadow moire using non-zero talbot distance |
| CN101403650B (en) * | 2008-11-21 | 2010-06-23 | 北京理工大学 | Differential confocal combination ultra-long focal length measuring method and apparatus |
| US8876290B2 (en) * | 2009-07-06 | 2014-11-04 | Wavetec Vision Systems, Inc. | Objective quality metric for ocular wavefront measurements |
| CN101995230A (en) * | 2010-10-29 | 2011-03-30 | 浙江大学 | Talbot effect-based aspheric surface detection system |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2016181206A1 (en) * | 2015-05-08 | 2016-11-17 | Uniwersytet Warszawski | The measurement setup for determining position of focal plane and effective focal length of an optical system and the method of determining position of focal plane and effective focal length of an optical system |
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