CN100401974C - Method and system for realizing axial super resolution in tomography of optical coherent - Google Patents
Method and system for realizing axial super resolution in tomography of optical coherent Download PDFInfo
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- 238000005316 response function Methods 0.000 claims abstract description 18
- 210000001747 pupil Anatomy 0.000 claims abstract description 15
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Abstract
An optical coherent tomography (OCT) method with axial super-resolution and its system are disclosed. A pupil filter is inserted between the collimating lens of OCT specimen arm and the object lens to decrease the width of main lobe of axial response function to less than coherent gate, so increasing its axial resolution.
Description
Technical field
The present invention relates to optical coherent chromatographic imaging (OCT) technology and optical ultra-discrimination technology, relate in particular to a kind of method and system of utilizing iris filter to realize axial super resolution in tomography of optical coherent.
Background technology
Optical coherent chromatographic imaging (Optical Coherence Tomography, be called for short OCT) be a kind of emerging optical image technology, with respect to traditional clinical imaging means, having advantages such as resolution height, fast, the radiationless damage of image taking speed, moderate cost, compact conformation, is the important potential instrument of basic medical research and clinical diagnostic applications.
Resolution is the important indicator of OCT technical development.The axial resolution of OCT is determined jointly by the focused condition of light source bandwidth and detecting light beam.Under detecting light beam weak focus condition, the main lobe width of corresponding axial response function is far longer than relevant gate-width degree, and the axial resolution of this moment is mainly by relevant door decision.The light source bandwidth is wide more, and relevant gate-width degree is just narrow more.Relevant gate-width degree is narrow more, and axial resolution is just high more.Therefore, the main path that is used for improving the OCT axial resolution at present comprises short pulse laser technology, non-linear super continuous spectrums generating technique, combined light source spectrum synthetic technology etc.But there is following limitation in these wideband light source technology: 1) achromatism to optical elements such as imaging lens requires to improve greatly; 2) ultra broadband high efficiency single-mode fiber device is difficult for obtaining; 3) ultrashort pulse laser costs an arm and a leg, operation inconvenience, and there are certain difficulty in miniaturization and commercialization.So, adopt the wideband light source technology to improve the axial resolution of OCT, often cost an arm and a leg, system complex, and have bottleneck on the device is difficult in existing basis and goes up and continue to improve.The light spectrum reshaping technology also can be improved the axial resolution of OCT to a certain extent, as spectral component makes spectral shape be tending towards smooth in the middle of suppressing, and realizes that the spectrum on the relative meaning is widened, and then improves the axial resolution of OCT.
Under detecting light beam strong-focusing condition, the main lobe width of its axial response function is approaching with relevant door.The main lobe width of light source bandwidth and axial response function is all directly related with the axial resolution of OCT.In this case, compressional axis is another approach that improves the OCT axial resolution to the main lobe width of receptance function.
Summary of the invention
The object of the present invention is to provide a kind of method and system that realize axial super resolution in tomography of optical coherent, these method and system are by inserting the iris filter of appropriate format, the main lobe width of axial response function is narrowed down within the relevant door, thus the axial super resolution of realization OCT; Simultaneously, the secondary lobe that is caused by super-resolution pupil filter is then suppressed by relevant door, the OCT coherent imaging is not produced effectively contribution, thereby guarantees that image contrast does not descend because of axial super resolution.
The objective of the invention is to be achieved through the following technical solutions:
One, a kind of method that realizes axial super resolution in tomography of optical coherent:
At the collimating mirror of optical coherent chromatographic imaging sample arm with survey between the object lens and insert iris filter, the main lobe width of axial response function is narrowed down within the relevant door, thereby realize the axial super resolution of optical coherent chromatographic imaging; Its concrete steps are as follows:
1) light that sends from port of fiber coupler is collimated by collimating mirror earlier, and then by iris filter, by surveying object lens focusing in sample, the axial main lobe width of the lighting point spread function of this moment obtains compression because of the effect of iris filter again;
2) reflected light that returns from sample and scattered light are collected via surveying object lens, once more by iris filter and collimating mirror, return fiber coupler then, converge with reference light from reference arm and interfere; The acceptance point spread function of this moment is consistent with the lighting point spread function, by the main lobe width of the axial response function of the two common decision less than relevant gate-width degree.
Described iris filter is made of N donut, and wherein N is the natural number greater than 2, and occurrence is definite according to the resolution requirement of different optical system,
Two, a kind of system that realizes axial super resolution in tomography of optical coherent:
Comprise wideband light source, 2 * 2 fiber couplers, detector, data collecting card, computer, reference arm and the sample arm of forming by collimating mirror, detection object lens and sample successively.Insert iris filter between the collimating mirror of sample arm and the detection object lens light path, the light that comes out from collimating mirror is by behind the iris filter, by surveying object lens focusing in sample, collect via surveying object lens from reflected light and scattered light that sample returns, by iris filter and collimating mirror, return fiber coupler then once more.
Described iris filter is amplitude type iris filter or phase-type iris filter, and iris filter is made of N donut, and wherein N is the natural number greater than 2, and occurrence is determined according to the resolution requirement of different optical system.
Principle of the present invention is: collimated beam is behind iris filter, and by surveying object lens focusing, near the light its focus distributes because of iris filter changes, and corresponding axial response function also changes thereupon.Adopt the iris filter of appropriate format, the main lobe width of OCT axial response function can be narrowed down within the relevant door.This moment, the axial resolution of OCT was no longer determined by the light source bandwidth, but was determined by the main lobe width of axial response function.Realized the raising of OCT axial resolution in this way.Simultaneously, the secondary lobe of axial response function is then suppressed by relevant door, does not participate in coherent imaging, thereby has guaranteed that image contrast does not descend because of axial super resolution.
Compare with background technology, the present invention has following advantage:
1) this method is simple, and is with low cost.Only need at the collimating mirror of conventional OCT sample arm and survey between the object lens and insert iris filter, the main lobe width of axial response function is narrowed down within the relevant door get final product.Adopt sophisticated binary optical technique and thin film technique to make iris filter, can reach very high precision and lower cost.This method that improves the OCT axial resolution has cheaply avoided the existing cost costliness of employing wideband light source technology, system complex, device to select defectives such as difficulty.
2) secondary lobe that is produced by super-resolution pupil filter tends to cause the decline of picture contrast, and this is a biggest obstacle of implementing the optical ultra-discrimination art in the conventional optical systems.But secondary lobe can be eliminated the influence of imaging in OCT, utilizes the inherent relevant door of OCT institute suppressed sidelobes participation coherent imaging fully, and this is a considerable advantage of implementing optical ultra-discrimination in OCT.
3) preliminary experiment shows, the axial resolution of OCT can be improved 10% at least by said method.
The present invention is the easy super-resolution technology of a kind of economy, can promote to realize the miniaturization and the commercialization of OCT system.
Description of drawings
Fig. 1 is the sample arm structural representation of OCT axial super resolution;
Fig. 2 is the amplitude type iris filter sketch map (is example with N=3) of optical shaft orientation super-resolution;
Fig. 3 is the phase-type iris filter sketch map (is example with N=3) of optical shaft orientation super-resolution;
Fig. 4 is the system schematic of OCT axial super resolution method.
Among the figure: 1, collimating mirror, 2, iris filter, 3, survey object lens, 4, sample, 5, wideband light source, 6,2 * 2 fiber couplers, 7, detector, 8, data collecting card, 9, computer, 10, reference arm.
The specific embodiment
The present invention is further illustrated below in conjunction with drawings and Examples:
Figure 1 shows that the sample arm structural representation of implementing the OCT axial super resolution, 1 is collimating mirror among the figure, and 2 is iris filter, and 3 for surveying object lens, and 4 is sample.Sample 4 is near the focus of surveying object lens 3.Collimating mirror 1, iris filter 2 and the 3 coaxial placements of detection object lens.The effective aperture of iris filter 2 equates with detection the unified of object lens 3, and is normalized to 1.Marginal portion outside iris filter 2 effective apertures can be used for the fixing of iris filter 2 because of the restriction of surveying object lens 3 bores does not participate in imaging.
As shown in Figure 1, the light from port of 2 * 2 fiber couplers sends earlier by collimating mirror 1 collimation, then by iris filter 2, focuses on the sample 4 by surveying object lens 3 again.Reflected light that returns from sample 4 and scattered light are collected via surveying object lens 3, once more by iris filter 2 and collimating mirror 1, converge with reference light from reference arm at the fiber coupler place then and interfere.In view of the concordance of illumination path in the feeler arm and receiving light path, corresponding lighting point spread function h
InWith acceptance point spread function h
OutAlso consistent, and determine by following formula:
I＝|h
in×h
out|
2 (2)
The pupil function of iris filter 2 is got when multi-form, and the axial response function changes thereupon.When taking the pupil function of appropriate format, the main lobe width of axial response function is retracted within the relevant door Δ l of OCT, thereby realizes the raising of OCT axial resolution.
The present invention for the raising of OCT axial resolution by relatively weighing between axial response function main lobe width and the relevant gate-width degree.For the OCT light source of Gaussian spectral distribution, its relevant gate-width degree is:
Wherein, λ is the centre wavelength of light source, and Δ λ is the light source bandwidth.
Iris filter 2 among the present invention is made up of N district circulus, its normalization pupil function
Expression formula be:
K wherein
iThe amplitude transmittance of representing i annulus, 0≤k
i≤ 1.
The bit phase delay of representing i annulus,
r
I-1And r
iRepresent outer radius in the normalization of i ring.When having only parameter k
iPerhaps
During variation, this expression formula corresponds respectively to amplitude type iris filter and phase-type iris filter.As embodiment, Fig. 2 has illustrated three district's amplitude type iris filters, and the distribution of amplitudes of its pupil function is:
Fig. 3 has illustrated three position facies pattern iris filters, and the position of its pupil function is distributed as mutually:
Shown in Figure 4 is the system schematic of implementing OCT axial super resolution method.Comprise wideband light source 5 (B﹠amp; WTek, Inc. the BWC-SLD of company, centre wavelength 1310nm, bandwidth 65nm), 2 * 2 fiber couplers 6 (the WBC type of clear and company of Futong, centre wavelength 1310nm, bandwidth 80nm), detector 7, data collecting card 8, computer 9, reference arm 10 and successively by collimating mirror 1, iris filter 2, survey the sample arm that object lens 3 and sample 4 are formed.Insert iris filter 2 between the collimating mirror 1 of sample arm and detection object lens 3 light paths.Theoretical and preliminary experiment shows: adopt pupil function suc as formula the iris filter shown in (5) and (6), the axial resolution of OCT can be improved 10% at least.
Claims (4)
1. method that realizes axial super resolution in tomography of optical coherent, it is characterized in that: at the collimating mirror of optical coherent chromatographic imaging sample arm with survey between the object lens and insert iris filter, the main lobe width of axial response function is narrowed down within the relevant door, thereby realize the axial super resolution of optical coherent chromatographic imaging; Its concrete steps are as follows:
1) light that sends from port of fiber coupler is collimated by collimating mirror earlier, and then by iris filter, by surveying object lens focusing in sample, the axial main lobe width of the lighting point spread function of this moment obtains compression because of the effect of iris filter again;
2) reflected light that returns from sample and scattered light are collected via surveying object lens, once more by iris filter and collimating mirror, return fiber coupler then, converge with reference light from reference arm and interfere; The acceptance point spread function of this moment is consistent with the lighting point spread function, by the main lobe width of the axial response function of the two common decision less than relevant gate-width degree.
2. a kind of method that realizes axial super resolution in tomography of optical coherent according to claim 1, it is characterized in that: described iris filter is made of N donut, wherein N is the natural number greater than 2, and occurrence is determined according to the resolution requirement of different optical system
Be the pupil function of iris filter,
Polar coordinate for pupil function; K wherein
iThe amplitude transmittance of representing i annulus, 0≤k
i≤ 1;
The bit phase delay of representing i annulus,
r
I-1And r
iRepresent outer radius in the normalization of i ring; When having only parameter k
iDuring variation, this expression formula is corresponding to the amplitude type iris filter; When having only parameter
During variation, this expression formula is corresponding to the phase-type iris filter; As parameter k
iWith
When all changing, this expression formula is corresponding to complex amplitude type iris filter.
3. a system that realizes axial super resolution in tomography of optical coherent comprises wideband light source (5), 2 * 2 fiber couplers (6), detector (7), data collecting card (8), computer (9), reference arm (10) and the sample arm of being made up of collimating mirror (1), detection object lens (3) and sample (4) successively; It is characterized in that: insert iris filter (2) between collimating mirror of sample arm (1) and detection object lens (3) light path, the light that comes out from collimating mirror (1) is by behind the iris filter (2), focus on sample (4) by surveying object lens (3), collect via surveying object lens (3) from reflected light and scattered light that sample (4) returns, by iris filter (2) and collimating mirror (1), return fiber coupler (6) then once more.
4. a kind of system that realizes axial super resolution in tomography of optical coherent according to claim 3, it is characterized in that: described iris filter (2) is amplitude type iris filter or phase-type iris filter, iris filter is made of N donut, wherein N is the natural number greater than 2, and occurrence is determined according to the resolution requirement of different optical system.
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Cited By (3)
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|---|---|---|---|---|
| CN101732035B (en) * | 2009-11-26 | 2011-11-09 | 浙江大学 | Method for optical super resolution based on optical path encoding and coherent synthesis |
| EP3067657A1 (en) * | 2015-03-11 | 2016-09-14 | Hitachi-LG Data Storage, Inc. | Optical measurement apparatus and optical measurement method |
| CN109596529A (en) * | 2018-12-28 | 2019-04-09 | 浙江大学 | A kind of Optical coherence tomography and method based on fiber array parallel detecting |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109115804B (en) * | 2017-06-22 | 2021-03-26 | 南京理工大学 | Device and method for quantitatively detecting subsurface defects of glass |
| CN108514404B (en) * | 2018-03-28 | 2021-08-10 | 深圳市太赫兹科技创新研究院 | Optical coherence tomography system |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101732035B (en) * | 2009-11-26 | 2011-11-09 | 浙江大学 | Method for optical super resolution based on optical path encoding and coherent synthesis |
| EP3067657A1 (en) * | 2015-03-11 | 2016-09-14 | Hitachi-LG Data Storage, Inc. | Optical measurement apparatus and optical measurement method |
| US10006755B2 (en) | 2015-03-11 | 2018-06-26 | Hitachi-Lg Data Storage, Inc. | Optical measurement apparatus and optical measurement method |
| CN109596529A (en) * | 2018-12-28 | 2019-04-09 | 浙江大学 | A kind of Optical coherence tomography and method based on fiber array parallel detecting |
| CN109596529B (en) * | 2018-12-28 | 2020-05-22 | 浙江大学 | Optical coherence tomography system and method based on optical fiber array parallel detection |
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