CN101576731B - Method for acquiring high-quality weak coherent light digital holographic phase reproduction image - Google Patents

Abstract

The invention discloses a method for acquiring a high-quality weak coherent light digital holographic phase reproduction image, wherein digital holographic light sources are weak coherent light sources. The method is characterized by comprising the following steps: (1) using a common shooting mode to acquire a strength image on the holographic record surface; (2) performing digital holographic record and reproduction to acquire a strength reproduction image and a phase reproduction image on the holographic record surface; (3) performing related operation on the strength image and the strength reproduction image to acquire a correlation coefficient; (4) changing the phase shift angle through a phase shifter for times, repeating the step (2) and the step (3), and acquiring a series of strength reproduction images, phase reproduction images and corresponding correlation coefficients; and (5) acquiring a phase reproduction image corresponding to the maximum correlation coefficient, namely the high-quality digital holographic phase reproduction image. The method does not need standard contrast, evaluates the quality of the phase reproduction image in real time through strength information of a detected object, acquires the high-quality phase reproduction image, and has great significance in application of digital holography.

Description

A kind of acquisition methods of high-quality weak coherent light digital holographic phase reproduction image

Technical field

The present invention relates to the Digital Holography field, particularly a kind of acquisition methods of high-quality weak coherent light digital holographic phase reproduction image.

Background technology

Digital hologram (Digital Holography) is the product that common holography, computer technology, electronic imaging technology combine.The recording process of digital holography and common holography is basic identical, and different is replaces holographic plate to come recorded hologram with electronographic devices such as ccd video camera, cmos cameras, and the holography that will the write down people's computing machine of striveing for survival; The reproduction process of digital holography is different fully with common holography, is with numerical calculation method the hologram of depositing people's computing machine to be carried out digital reproduction.Compare with common holography, following obvious advantage is arranged: (one) is owing to replace holographic plate to come recorded hologram with electronographic device, the required time shutter can be very short, the procedure for wet processing that does not have chemical silver salt dry plate, but each transients of continuous recording moving object realizes the continuous real-time online holographic recording under the video; (2) pass through digital reproduction, can reproduce the complex amplitude of thing light wave, the distributed in three dimensions that can quantitatively show object according to the phase information in the thing multiplexed optical wave amplitude, the three-dimensional distribution map that obtains object similarly is the great advantage of holograph with respect to common photograph, and quantitative distributed in three dimensions shows, be again the advantage of digital hologram with respect to common holography, the application vigor that traditional holography is shone again make new advances.

Because the high coherence of laser, make to have the parasitic interaction noise that optical element produced in laser speckle noise and the recording beam path inevitably in the laser hologram, have a strong impact on the quality of digital hologram reproduction figure.In order to suppress these noises, the weak coherent light digital holographic technology has caused people's interest, but because the spatial coherence in weak coherent light source is poor, generally only is applicable to coaxial digital hologram.For cancellation twin image and Zero-order diffractive, generally adopt the method for phase shift to come the coaxial digital hologram of digital reproduction.

In many application of digital hologram, mainly be to utilize the thing light wave position phase of reproducing, the reproduction quality of thing light wave position phase directly has influence on its effect.The factor that influences the digital holographic phase reproduction quality has a lot, and its reproduction quality of how to evaluate is a very important problem.Because the true position of thing light wave is ignorant mutually, therefore the phasor that the digital reconstruction of hologram is obtained is just estimated very difficulty, and general at present employing is carried out digital reproduction to reference material and estimated.Reference material is carried out the method that digital reproduction estimates is not real-time estimating method but adopt.In actual application, the drift of weak coherent light source peak wavelength is subjected to the influence of environment temperature, supply voltage easily, the instability of hologram recording apparatus, phase-shifter etc., the capital exerts an influence to the angle of phase displacement of phase-shifter, thereby has influence on the record of hologram and to the high-quality phase reproduction of testee.Employing is carried out the method that digital reproduction estimates to reference material and will be lost efficacy in this case.Therefore, the quality of digital holographic phase reproduction is carried out Real-Time Evaluation just seem very necessary, can optimize and the real-time digital hologram reproducing technology parameter of adjusting, obtain high-quality digital holographic phase reproduction image, this application to digital hologram has very important significance.

Summary of the invention

The objective of the invention is to provide a kind of acquisition methods of high-quality digital holographic phase reproduction image at the deficiencies in the prior art.

Technical scheme of the present invention is as follows:

A kind of acquisition methods of high-quality weak coherent light digital holographic phase reproduction image, the light source of digital hologram is the weak coherent light source, it is characterized in that may further comprise the steps:

(1) obtains the intensity map of holographic record surface with common photographic means;

(2) carry out digital hologram record and reproduction, obtain the intensity reproduction figure and the phase reproduction image of holographic record surface;

(3) intensity map and intensity reproduction figure are carried out related operation, obtain related coefficient;

(4) repeatedly change angle of phase displacement, repeating step (2)～(3) by phase-shifter; Obtain a series of intensity reproduction figure, phase reproduction image and corresponding related coefficient;

(5) phase reproduction image of Zui Da related coefficient correspondence is high-quality digital holographic phase reproduction image.

The intensity map of the holographic record surface that obtains with common photographic means, be: close the reference light in the digital hologram pen recorder, only allow the thing light wave enter video camera, with video camera the intensity of the thing light wave of holographic record surface is noted with common photographic means, transferred to computing machine and also store with the image file form.

Carry out digital hologram record and reproduction, obtain the intensity reproduction figure and the phase reproduction image of holographic record surface, be: guaranteeing under the situation that the thing light wave is constant and video camera is motionless, open reference light and carry out the digital hologram record with video camera, with camera record to digital hologram transfer to computing machine, computing machine carries out thing light wave digital reproduction with the digital hologram that records, and the intensity that obtains holographic record surface is reproduced figure and phase reproduction image.

Further, the described phase-shifter of step (4) is the piezoelectric ceramics phase-shifter, changes angle of phase displacement by the driving voltage that changes the piezoelectric ceramics phase-shifter.

Principle of work of the present invention is as follows:

At first close reference light in the digital hologram pen recorder with photoswitch, only allow the thing light wave enter video camera, with video camera the thing light wave intensity of holographic record surface is noted with common photographic means, transferred to computing machine and also store with the form of image file.Guaranteeing under the situation that the thing light wave is constant, video camera is motionless, open reference light and carry out holographic recording with video camera, with camera record to hologram transfer to computing machine, computing machine carries out digital hologram with the digital hologram that records and reproduces, and the intensity that obtains holographic record surface is reproduced figure and phase reproduction image.The intensity map that above-mentioned video camera is photographed with common photographic means and reproduce the intensity reproduction figure that obtains by digital hologram and carry out related operation obtains related coefficient again.Repeatedly change angle of phase displacement, repeat above-mentioned steps.Related coefficient is big more, it is good more that explanation is reproduced the intensity reproduction figure reproduction quality that obtains by digital hologram, again because intensity reproduction figure is related with phase reproduction image, so intensity map that common photographic means photographs and the related coefficient of reproducing between the intensity reproduction figure that obtains by digital hologram are big more, it is also good more to illustrate that the phase reproduction image that obtains by the digital hologram reproduction reproduces quality.

Digital hologram reproduces can obtain intensity reproduction figure and phase reproduction image simultaneously.Because intensity reproduction figure compares with the intensity map that obtains with common photographic means, aspect picture quality, do not have advantage and seldom be utilized; Position phasor with common photographic means can't obtain owing to reflected the three-dimensional information of testee, and receives much attention.The present invention has utilized intensity map that common photographic means obtains and the association between the digital hologram intensity reproduction figure, digital hologram intensity is reproduced the related of figure and phase reproduction image, do not need the standard control thing, the quality of the strength information Real-Time Evaluation phase reproduction image by measured object itself.

The present invention does not need to contrast evaluation with reference material, but according to the digital hologram digital reproduction result to measured object itself, can provide the evaluation of phase reproduction quality immediately, obtains optimum digital holographic phase reproduction image.

Description of drawings

Fig. 1 is a digital hologram pen recorder synoptic diagram.

Fig. 2 is the experimental provision synoptic diagram of embodiment.Among the figure, the 1-LED light source; 2-beam-expanding collimation mirror; The 3-beam splitter; The 4-object beam; The 5-object under test; The 6-photoswitch; The 7-reference beam; The 8-catoptron; The 9-video camera; The 10-computing machine; The 11-phase shift driver; The 12-phase-shifter.

Fig. 3 is the intensity map that video camera photographs among the embodiment.

Fig. 4 is the intensity reproduction figure that obtains under the phase shift driving voltage of 6.0V among the embodiment.

Fig. 5 is the intensity reproduction figure that obtains under the phase shift driving voltage of 6.6V among the embodiment.

Fig. 6 is the intensity reproduction figure that obtains under the phase shift driving voltage of 7.2V among the embodiment.

Fig. 7 is the related coefficient under different phase shift driving voltages among the embodiment.

Fig. 8 is the phase reproduction image that obtains under the phase shift driving voltage of 6.0V among the embodiment.

Fig. 9 is the phase reproduction image that obtains under the phase shift driving voltage of 6.6V among the embodiment.

Figure 10 is the phase reproduction image that obtains under the phase shift driving voltage of 7.2V among the embodiment.

Figure 11 is that Fig. 8, the Fig. 9 that obtains under different related coefficients among the embodiment, the digital hologram of Figure 10 dotted line row reproduce position value mutually.

Embodiment

With digital hologram recording beam path as shown in Figure 1 is example, but is not limited thereto recording beam path.Open light source 1, close photoswitch 6, the light beam that light source 1 sends shines object under test 4 through beam-expanding collimation mirror 2, beam splitter 3, light beam is formed object beam 5 by object under test 4 reflection backs, object beam 5 is injected in the video camera 9 through beam splitter 3, intensity map with common photographic means shooting thing light wave transfers to this intensity image computing machine 10 and storage again.In assurance device under the motionless situation of parts relevant with the thing light wave, open photoswitch 6, allow reference light 7 interfere through spectroscope 3 and object beam 6, carrying out hologram with video camera 9 takes, the hologram that video camera 9 is recorded transfers to computing machine 10, computing machine 10 carries out thing light wave digital reproduction with the digital hologram that records again, and the thing light wave intensity that obtains holographic record surface is reproduced figure and phase reproduction image.The intensity map that the common photographic means of above-mentioned video camera 10 usefulness is photographed and carry out related operation by the intensity reproduction figure that digital hologram reproduce to obtain again, carry out related operation and can adopt following formula:

${\mathrm{\ρ}}_{\mathrm{AB}}=\left|\frac{\mathrm{C\; O\; V}(A,B)}{\sqrt{D_A{D}_B}}\right|,---\left(1\right)$

$D_A=\frac{1}{\mathrm{mn}}\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{(A_{\mathrm{ij}}-\stackrel{\‾}{A})}^2,---\left(2\right)$

$D_B=\frac{1}{\mathrm{mn}}\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{(B_{\mathrm{ij}}-\stackrel{\‾}{B})}^2,---\left(3\right)$

$\mathrm{COV}(A,B)=\frac{1}{\mathrm{mn}}\underset{i=1}{\overset{m}{\mathrm{\Σ}}}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}(A_{\mathrm{ij}}-\stackrel{\‾}{A})(B_{\mathrm{ij}}-\stackrel{\‾}{B}),---\left(4\right)$

Wherein A, B represent to carry out the matrix of two width of cloth images of related operation; ρ _ABBe the related coefficient that to calculate, 0≤ρ _AB≤ 1; M, n be the total line number of presentation video matrix and total columns respectively; A _Ij, B _IjThe matrix element of representing two width of cloth image arrays respectively; A, B represent the matrix element mean value of two width of cloth image arrays respectively.

Related operation ρ _ABBig more, it is good more to illustrate that the phase reproduction image that obtains by the digital hologram reproduction reproduces quality.

Embodiment

In the weak coherent light phase shift digital holographic phase reproduction that with LED is light source, owing to often occur unsettled phase displacement error easily, phase displacement error is bigger to the phase reproduction quality influence again, the technical program can be applicable to its phase reproduction quality Real-Time Evaluation, and in real time calibration phase displacement error, preferred reproduced image.

Fig. 2 is the experimental provision synoptic diagram of present embodiment.Phase-shifter 12 is to make of piezoelectric ceramics (PZT), and to its calibration, when driving voltage was 6.3V, corresponding angle of phase displacement was with helium-neon laser (wavelength 632.8nm)

When using LED as light source, because the peak wavelength of LED can be along with temperature and injection current drift, and the peak wavelength diversity of LED is bigger, even the same model of same manufacturer production, the peak wavelength of each LED is also slightly different, this makes the demarcation of phase-shifter encounter difficulties, and in addition, also there is non-linear and stochastic error in the piezoelectric ceramics phase-shifter.We apply different driving voltages to continuously change the angle of phase displacement of phase-shifter to phase-shifter near 6.3V, carry out phase shift digital hologram record and reproduction according to following steps.Open led light source 1, close photoswitch 6, the intensity map (as shown in Figure 3) with video camera 9 shooting thing light waves transfers to this intensity image computing machine 10 and storage again.In assurance device under the motionless situation of parts relevant with the thing light wave, open photoswitch 6, carry out four step phase shift holograms with video camera 9 and take, the hologram that video camera 9 is recorded transfers to computing machine 10, and computing machine 10 carries out thing light wave digital reproduction with the digital hologram that records again.Fig. 4, Fig. 5, Fig. 6 are respectively under the situation of 6.0V, 6.6V, 7.2V phase shift driving voltage, four step phase shift digital hologram remember strength figure of acquisition.

The corresponding relation of table 1 phase shift driving voltage and related coefficient

Voltage (V)	Related coefficient	Voltage (V)	Related coefficient	Voltage (V)	Related coefficient
						?4	0.6665	?6.0	0.8194	?8.0	0.7503
?4.2	0.6886	?6.2	0.8439	?8.2	0.7336
						?4.4	0.7125	?6.4	0.8208	?8.4	0.6909
?4.6	0.7096	?6.6	0.8700
						?4.8	0.6849	?6.8	0.8546
?5.0	0.7332	?7.0	0.8061
						?5.2	0.7517	?7.2	0.8294
?5.4	0.8070	?7.4	0.7712
						?5.6	0.7819	?7.6	0.7845
?5.8	0.8332	?7.8

Table 1 is under the situation of different phase shift driving voltages, the four step phase shift digital hologram remember strength figure that obtain and Fig. 3 carry out the related coefficient that obtains behind the related operation, Fig. 7 is the figure of data correspondence in the table 1, as can be seen from Figure 7, related coefficient maximum under the situation of 6.6V phase shift driving voltage, this is explanation just, phase displacement error minimum when 6.6V, and the position phase images that digital hologram reproduces is best in quality.Fig. 8, Fig. 9, Figure 10 are respectively under the situation of 6.0V, 6.6V, 7.2V phase shift driving voltage, and four step phase shift digital holograms of acquisition reproduce the position phasor.Figure 11 is that the digital hologram of dotted line column among Fig. 8, Fig. 9, Figure 10 reproduces position value mutually, and among Figure 11, it is the pairing position of 7.2V, 6.6V, 6.0V value mutually that 3 curves from top to bottom are respectively the phase shift driving voltage.

Claims (4)

1. the acquisition methods of a high-quality weak coherent light digital holographic phase reproduction image, the light source of digital hologram is the weak coherent light source, it is characterized in that may further comprise the steps:

(1) obtains the intensity map of holographic record surface with common photographic means;

(2) carry out digital hologram record and reproduction, obtain the intensity reproduction figure and the phase reproduction image of holographic record surface;

(3) intensity map and intensity reproduction figure are carried out related operation, obtain related coefficient;

(4) repeatedly change angle of phase displacement, repeating step (2)～(3) by phase-shifter; Obtain a series of intensity reproduction figure, phase reproduction image and corresponding related coefficient;

(5) phase reproduction image of Zui Da related coefficient correspondence is high-quality digital holographic phase reproduction image.

2. the acquisition methods of high-quality weak coherent light digital holographic phase reproduction image according to claim 1, it is characterized in that: the intensity map of the holographic record surface that obtains with common photographic means, be: close the reference light in the digital hologram pen recorder, only allow the thing light wave enter video camera, with video camera the intensity of the thing light wave of holographic record surface is noted with common photographic means, transferred to computing machine and also store with the image file form.

3. the acquisition methods of high-quality weak coherent light digital holographic phase reproduction image according to claim 2 is characterized in that:

Carry out digital hologram record and reproduction, obtain the intensity reproduction figure and the phase reproduction image of holographic record surface, be: guaranteeing under the situation that the thing light wave is constant and video camera is motionless, open reference light, reference light is interfered through spectroscope and thing light wave, carry out the digital hologram record with video camera, with camera record to digital hologram transfer to computing machine, computing machine carries out thing light wave digital reproduction with the digital hologram that records, and the intensity that obtains holographic record surface is reproduced figure and phase reproduction image.

4. according to the acquisition methods of each described high-quality weak coherent light digital holographic phase reproduction image of claim 1 to 3, it is characterized in that: the described phase-shifter of step (4) is the piezoelectric ceramics phase-shifter, changes angle of phase displacement by the driving voltage that changes the piezoelectric ceramics phase-shifter.

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