CN106556340A - The finding method of the zero order fringe that the wide spectrum based on modulation degree is interfered - Google Patents
The finding method of the zero order fringe that the wide spectrum based on modulation degree is interfered Download PDFInfo
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- CN106556340A CN106556340A CN201611108732.8A CN201611108732A CN106556340A CN 106556340 A CN106556340 A CN 106556340A CN 201611108732 A CN201611108732 A CN 201611108732A CN 106556340 A CN106556340 A CN 106556340A
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- interference
- fringe
- zero order
- modulation degree
- wide spectrum
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B9/00—Measuring instruments characterised by the use of optical techniques
- G01B9/02—Interferometers
- G01B9/02083—Interferometers characterised by particular signal processing and presentation
- G01B9/02084—Processing in the Fourier or frequency domain when not imaged in the frequency domain
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
Abstract
The invention discloses a kind of finding method of the zero order fringe of the wide spectrum interference based on modulation degree, in interference fringe, using two-dimensional Fourier transform, obtain the spectrum information of interference pattern, then fundamental frequency information extraction, and then inverse Fourier transform again are carried out, and the information transfer system of single pixel point in single frames bar graph are obtained by correlation computations, it is last to be directed to single pixel point location maximum modulation angle value along scanning direction, so that it is determined that zero order fringe.This method can eliminate the impact that light strong nonstability is brought to measurement result, eliminate the interference of high frequency and background information, improve accuracy and sensitivity that traditional wide spectrum interferes topography measurement method, it is possible to differentiate automatically the fluctuations of object or crest.
Description
Technical field
The present invention relates to the technical field of optical detection three-dimensional appearance, more particularly to a kind of wide spectrum based on modulation degree is done
The finding method of the zero order fringe for relating to.
Background technology
It is to find the position of zero order fringe that wide spectrum interferes the key of shape recovery.Extremum method is by the light intensity of certain pixel
Value is extracted, and it is zero order fringe position to find the corresponding position of light intensity maximum, and the method is simple, but requires sampling frequency
Rate is higher, and the disturbing factor such as light source fluctuation affects big to measurement result.With regard to gravity model appoach, interference fringe is with zero level bar in theory
The position of line is symmetrical, then interference signal position of centre of gravity is exactly zero order fringe position, but the method requires higher light
Strong curve symmetry.So it is proposed that a kind of method analyzed with simple Fourier spectrum is solving these problems, this side
Method improves accuracy and sensitivity, eliminates light strong nonstability, it is suppressed that the interference of high-frequency signal, can also differentiate automatically
The fluctuations of object or crest.
Chinese patent CN101324422A disclosed a kind of white light interference sample surface shapes in 2008 and finely divides
The method and its device of cloth, obtains amplitude-modulated signal and light source by being input into a series of white-light fringe signals of computer
The related cosine function of spatial distribution envelope distribution, some amplitudes are collected by unequal interval time sampling method and are adjusted
The centrifugal pump of signal processed, recycles interpolation algorithm to determine the center i.e. zero order fringe position of envelope, and the method effectively subtracts
The sampling time is lacked and has improved sampling efficiency, but the impact that light strong nonstability and background information are brought can not have been eliminated.
The content of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the invention provides the zero of a kind of wide spectrum interference based on modulation degree
The finding method of level striped, can eliminate the unstable impact brought to measurement result of light intensity.
The technical solution adopted in the present invention is：
The finding method of the zero order fringe that a kind of wide spectrum based on modulation degree is interfered, in interference fringe, using two dimension
Fourier transformation, obtains the spectrum information of interference pattern, then carries out fundamental frequency information extraction, and then inverse Fourier transform again, pass through
Correlation computations obtain the information transfer system of single pixel point in single frames bar graph, finally fixed for single pixel point along scanning direction
Position maximum modulation angle value, so that it is determined that zero order fringe.This method can eliminate what light strong nonstability was brought to measurement result
Affect, eliminate the interference of high frequency and background information, improve accuracy and sensitivity that traditional wide spectrum interferes topography measurement method,
And the fluctuations of object or crest can be differentiated automatically.
Further, the interference system that the method is utilized adopts white light source, is produced using Mirau interference microscopes dry
Relate to, scanned by Piezoelectric Ceramic, interference image is gathered by CCD.When optical path difference is zero, the zero order fringe of each wavelength is weighed completely
Close, with the increase of optical path difference and interference fringe series, interference fringe brightness is gradually reduced.
Further, the light distribution formula of the speckle pattern interferometry image pixel for collecting is become with Euler's formula
Two-dimensional Fourier transform is carried out after changing.
Further, in order to preferably extract information transfer system, and background information contained by zero level frequency spectrum and modulation degree without
Close, also for elimination impact of the high-frequency signal to measurement result, so the spectrogram obtained after Fourier transformation is filtered,
Extract fundamental frequency spectrum information, it is only necessary to retain any one in two one-level frequency spectrums comprising spectral information.
Further, inverse Fourier transform is carried out to fundamental frequency, single pixel point in single frames bar graph is obtained by calculating
Information transfer system, is finally directed to single pixel point location maximum modulation angle value along scanning direction, so that it is determined that zero order fringe.
The present invention principle be：
The light distribution of the speckle pattern interferometry image for collecting is represented by：
G (x, y)=a (x, y)+b (x, y) cos [φ (x, y)]
In formula, a (x, y) is background intensity, and b (x, y) is fringe contrast, and φ (x, y) is phase place.
For ease of Fourier transformation above formula Jing after Euler's formula conversion it is：
Wherein, * represents that c (x, y) and c* (x, y) is a pair of conjugate complex numbers, whereinTo upper
Formula carries out the two-dimensional Fourier transform with regard to x with Fast Fourier Transform (FFT) FFT, obtains G (f, y)=A (f, y)+C (f-f0, y)+C*
(f+f0, y), in formula, capitalization represents Fourier spectrum, and f is spatial frequency.Due to space variable a (x, y), b (x, y) and
φ (x, y) is than spatial frequency f0What is changed is slow, so frequency spectrum is by carrier frequency f0Separate.
In order to preferably extract information transfer system, and background information contained by zero level frequency spectrum is unrelated with modulation degree, also for disappearing
Except impact of the high frequency to result, so being filtered to frequency spectrum, it is only necessary to retain in two one-level frequency spectrums containing spectral information
Any one.
Arbitrary C (f-f in one-level frequency spectrum0, inverse Fourier transform is carried out y), c (x, y) is obtained, contrast can be calculated
Degree,
Information transfer system is can be calculated, modulation degree maximum position is the position of zero order fringe.
Compared with prior art, the invention has the beneficial effects as follows：
The method of the present invention eliminates light strong nonstability, eliminates the impact of background information and high frequency to result, improves
Accuracy and sensitivity, it is possible to differentiate automatically the fluctuations of object or crest.
Description of the drawings
Fig. 1 is the flow chart of the finding method of the zero order fringe that a kind of wide spectrum based on modulation degree of the present invention is interfered；
Fig. 2 is modulation degree transition diagram and its scanning process.
Specific embodiment
The present invention is further described below in conjunction with the accompanying drawings.
The zero order fringe finding method flow chart that a kind of wide spectrum based on modulation degree of the present invention is interfered is as shown in figure 1, tool
Body step is as follows：
Step (1), longitudinal scanning obtain multiframe interference fringe picture；
The a certain pixel light distribution formula of the speckle pattern interferometry image for collecting is：
G (x, y)=a (x, y)+b (x, y) cos [φ (x, y)]
In formula, a (x, y) is background intensity, and b (x, y) is fringe contrast, and φ (x, y) is phase place.
Step (2), the multiframe interference fringe picture that step (1) is obtained is carried out Two-dimensional FFT conversion obtain Fourier spectrum figure
Information；
To carry out Fourier transformation, by above formula Jing after Euler's formula conversion it is：
Wherein, * represents that c (x, y) and c* (x, y) is a pair of conjugate complex numbers, whereinTo upper
Formula carries out the two-dimensional Fourier transform with regard to x with Fast Fourier Transform (FFT) FFT, obtains G (f, y)=A (f, y)+C (f-f0, y)+C*
(f+f0, y), capitalization represents Fourier spectrum, and f is spatial frequency.
Step (3), step (2) is obtained Fourier spectrum figure information carry out fundamental frequency frequency spectrum extract obtain fundamental frequency information；
In order to preferably reappear the details of determinand, and background information contained by zero level frequency spectrum is unrelated with modulation degree, also for
Impact of the high frequency to result is eliminated, so extraction fundamental frequency information is filtered to frequency spectrum, it is only necessary to retain in two one-level frequency spectrums
Any one.
Step (4), background light intensity elimination is carried out to the fundamental frequency information that step (3) is obtained, obtain phase-modulation degree information；
Step (5), normalization modulation degree numerical value, to one-level frequency spectrum in arbitrary C (f-f0, inverse Fourier transform is carried out y),
C (x, y) is obtained, contrast can be calculated,
Can be calculated information transfer system.
Step (6), modulation degree maximum of finding longitudinal to the modulation degree numerical value after normalization are worth to zero order fringe, modulation degree
Transition diagram and its scanning process are as shown in Figure 2.
Claims (5)
1. a kind of finding method of the zero order fringe that wide spectrum based on modulation degree is interfered, is characterized in that：In interference fringe, profit
With two-dimensional Fourier transform, the spectrum information of interference pattern is obtained, then carry out fundamental frequency information extraction, and then another mistake Fourier becomes
Change, the information transfer system of single pixel point in single frames bar graph is obtained by correlation computations, finally along scanning direction for single
Pixel point location maximum percentage modulation value, so that it is determined that zero order fringe.
2. the finding method of the zero order fringe that a kind of wide spectrum based on modulation degree according to claim 1 is interfered, which is special
Levying is：The interference system that the method is utilized adopts white light source, produces interference using Mirau interference microscopes, by piezoelectric ceramics
Scanning is driven, interference image is gathered by CCD, when optical path difference is zero, the zero order fringe of each wavelength is completely superposed, with optical path difference
And the increase of interference fringe series, interference fringe brightness is gradually reduced.
3. the finding method of the zero order fringe that a kind of wide spectrum based on modulation degree according to claim 1 is interfered, which is special
Levying is：The light distribution formula of the speckle pattern interferometry image pixel for collecting is entered with Euler's formula
In leaf transformation.
4. the finding method of the zero order fringe that a kind of wide spectrum based on modulation degree according to claim 1 is interfered, which is special
Levying is：In order to preferably extract information transfer system, and background information contained by zero level frequency spectrum is unrelated with modulation degree, high also for eliminating
Impact of the frequency signal to measurement result, so the spectrogram obtained after Fourier transformation is filtered, extracts fundamental frequency frequency spectrum letter
Breath, it is only necessary to retain any one in two one-level frequency spectrums comprising spectral information.
5. the finding method of the zero order fringe that a kind of wide spectrum based on modulation degree according to claim 1 is interfered, which is special
Levying is：Inverse Fourier transform is carried out to fundamental frequency, the information transfer system of single pixel point in single frames bar graph is obtained by calculating, finally
Single pixel point location maximum modulation angle value is directed to along scanning direction, so that it is determined that zero order fringe.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107388958A (en) * | 2017-07-11 | 2017-11-24 | 中国科学院光电技术研究所 | Micro-nano structure two-dimensional super-resolution detection method based on structure light |
| CN108709494A (en) * | 2018-03-26 | 2018-10-26 | 中国民航大学 | A kind of white light interference signal background light intensity real-time separation method |
| CN115307746A (en) * | 2022-08-10 | 2022-11-08 | 苏州科技大学 | Interferometric phase calculation method for monochromatic light |
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| JP2005345246A (en) * | 2004-06-02 | 2005-12-15 | Nikon Corp | Interference fringe analysis method, interference fringe analysis program and interference measuring device |
| CN101324422A (en) * | 2007-06-12 | 2008-12-17 | 西安普瑞光学仪器有限公司 | Method and apparatus of fine distribution of white light interference sample surface shapes |
| CN101755187A (en) * | 2007-07-19 | 2010-06-23 | 齐戈股份有限公司 | Generating model signals for interferometry |
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| JP2005345246A (en) * | 2004-06-02 | 2005-12-15 | Nikon Corp | Interference fringe analysis method, interference fringe analysis program and interference measuring device |
| CN101324422A (en) * | 2007-06-12 | 2008-12-17 | 西安普瑞光学仪器有限公司 | Method and apparatus of fine distribution of white light interference sample surface shapes |
| CN101755187A (en) * | 2007-07-19 | 2010-06-23 | 齐戈股份有限公司 | Generating model signals for interferometry |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107388958A (en) * | 2017-07-11 | 2017-11-24 | 中国科学院光电技术研究所 | Micro-nano structure two-dimensional super-resolution detection method based on structure light |
| CN108709494A (en) * | 2018-03-26 | 2018-10-26 | 中国民航大学 | A kind of white light interference signal background light intensity real-time separation method |
| CN115307746A (en) * | 2022-08-10 | 2022-11-08 | 苏州科技大学 | Interferometric phase calculation method for monochromatic light |
| CN115307746B (en) * | 2022-08-10 | 2023-08-18 | 苏州科技大学 | Interferometry phase calculation method for monochromatic light |
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