CN101620273A

CN101620273A - Method for detecting underwater object by relevance imaging

Info

Publication number: CN101620273A
Application number: CN200910114294A
Authority: CN
Inventors: 熊显名; 张丽娟
Original assignee: Guilin University of Electronic Technology
Current assignee: Guilin University of Electronic Technology
Priority date: 2009-08-08
Filing date: 2009-08-08
Publication date: 2010-01-06
Anticipated expiration: 2029-08-08
Also published as: CN101620273B

Abstract

The invention provides a method for detecting an underwater object by relevance imaging, which comprises the following steps: a pair of quantum entanglement two-photons are obtained by a quantum entanglement effect and respectively used as signal light and idle light; the signal light is projected to an object by an imaging lens, and reflection light carrying object information is received by a detector D1; after being freely transmitted in the certain distance, the idle light enters a scanning detector D2 made of fibers; and a combined detection image of the two detectors is recorded by the coordinate function which corresponds to the fibers when dynamically scanning at the plane of the input end so as to confirm the image information of the object, the depth of the position in which the object is located, and the like. The method can be used for measuring water depth, detecting and recognizing submerged rocks, submarines, fish school, mines and wracks, surveying and mapping submarine geomorphology, and the like; and compared with a remote sensing spectral imaging technology, the method can improves the resolution by several times.

Description

Utilize the method for relevance imaging detecting underwater object

Technical field

The present invention relates to the detection of submarine target, i.e. the two-photon that produces with the quantum entanglement effect method of removing detecting underwater object as flashlight and unused light respectively.

Background technology

The method of carrying out Underwater Target Detection at present is to utilize remote sensing light spectrum image-forming technology: radiation of light source to the water surface, is obtained submarine target image information with entering in the water through the reflected light information of object by the reflective information that compares the water surface.The intensity of reflected light of the water surface is relevant with water surface situation, but except the situation that direct reflection takes place, generally only accounts for about 3.5% of incident light; Light in the part transmission water inlet is constituted scattered light in the water by suspension bed sediment in the water and organic-biological scattering, and the part of wherein returning the water surface is called rear orientation light; Light in the part transmission water inlet arrives object (or water-bed) and reflects, constitutes object (or water-bed) reflected light, and this part light has carried the information of object (or water-bed), with the dried up reflected light of the common composition of rear orientation light; The light that remote sensor receives comprises water-reflected light, dried up reflected light and sky scattering light.Can extract water colour, the depth of water and sea-bed topography, the object information of each side such as the degree of depth and shape under water by remote sensing.But the resolution of remote sensing light spectrum image-forming technology is not very high.

Summary of the invention

The objective of the invention is to provide a kind of method of utilizing the relevance imaging detecting underwater object, this method can improve the resolution of light spectrum image-forming greatly.

Realize that the object of the invention technical scheme is:

(frequency is ω with a branch of high-frequency _t) laser removes to shine the second nonlinear crystal, high frequency photon of every annihilation will produce two low frequency photons simultaneously, with them and be used separately as flashlight and unused light.Flashlight is through imaging len directive object, and the reflected light that carries object information is detected device D ₁Receive; Unused light enters the scan detector D that is made by optical fiber after freely propagating certain distance ₂, write down two detector combined detection images with optical fiber coordinate function of correspondence when the dynamic scan of input end plane, and then the image information of definite object and the residing degree of depth of object etc.

The method of detecting underwater object of the present invention comprises the steps:

(1) will separate through beam splitter by the two-photon that tangles that nonlinear crystal produces, form two-beam, and two-beam is used separately as flashlight and unused light;

(2) allow flashlight pass through directive submarine target thing behind the imaging convex lens;

(3) photodetector D is set ₁, collect the reflected signal light that after the object reflection, has carried the information of object;

(4) scan detector D is set ₂, the unused light behind the segment distance, detector D are freely propagated in collection ₁And D ₂Be complementary;

(5) use scan detector D ₂Optic fibre input end when carrying out dynamic scan the coordinate function of correspondence write down detector D ₁And D ₂The combined detection image;

(6) the definition image distance is S _i, S _iFor from incident optical signal at the plane of incidence of imaging len through beam splitter to nonlinear crystal, and then the path from non-linear capable crystal along unused light arrives the distance on image (scanning optic fibre input end plane), the definition object distance is S _o, S _oBe the distance of submarine target thing to imaging len.Adjust image distance S _i, work as S _i, S _oSatisfy the thin lens Gauss equation with the imaging len focal distance f

\frac{1}{S_{o}} + \frac{1}{S_{i}} = \frac{1}{f}

The time can obtain image under the combined detection, at this moment, by S _i, f can calculate object distance S _o, and then obtain the underwater degree of depth of object.

This method is through the experimental verification with transmission imaging, and the result shows it is feasible, and this experimental technique is: change the reflection-type object into the transmission-type openworking template, and flashlight enters detector D through openworking template ₁, all the other devices remain unchanged.This moment object distance S _oBe the distance of openworking template to imaging len; Image distance S _iStill be from incident optical signal at the plane of incidence of imaging len through beam splitter to nonlinear crystal, and then the path from non-linear capable crystal along unused light arrives the distance on image (scanning optic fibre input end plane).When object distance S is set _o=600mm, image distance S _i=1200mm during imaging len focal distance f=400mm, has obtained amplifying the clear template image of twice just.As can be seen, S _o, S _i, f satisfies Gauss formula.

The degree of depth of this method detecting underwater object can reach about 80m.

The advantage of this detection method is: can sound the depth of the water, survey identification submerged reef, submarine, the shoal of fish, submarine mine, wrack, and the mapping sea-bed topography etc., to compare with remote sensing light spectrum image-forming technology in the past, resolution can improve several times.

Description of drawings

The invention will be further elaborated below in conjunction with the drawings and specific embodiments.

Fig. 1 is for utilizing relevance imaging detecting underwater object synoptic diagram;

Fig. 2 is the stretch-out view of Fig. 1 light path part on straight line.

Embodiment

The instrument and equipment that this detection method needs comprises high-frequency LASER Light Source, nonlinear crystal, beam splitter, imaging len, light filter, photodetector, two-dimensional scan fiber-optical probe and combined detection device.Its detection method is: (frequency is ω with a branch of high-frequency _t) laser removes to shine the second nonlinear crystal, high frequency photon of every annihilation will produce two low frequency photons simultaneously, forms the two-photon light source; With beam splitter the two-photon light source is divided into two different directions, (frequency is ω to make flashlight respectively _s) and unused light (frequency is ω _i); Flashlight by imaging convex lens (focal length is f) and light filter after directive under water through object, the reflected light on object is by photodetector D ₁Receive; After unused light is freely propagated a segment distance, enter the scan detector D that forms by optical fiber ₂Use scan detector D ₂Optic fibre input end when carrying out dynamic scan the coordinate function of correspondence write down detector D ₁And D ₂The combined detection image; When meeting some requirements, (below will be described), can get the combined detection image.

The definition image distance is S _i, S _iFor from incident optical signal at the plane of incidence of imaging len through beam splitter to nonlinear crystal, and then the path from non-linear capable crystal along unused light arrives the distance of image, the definition object distance is S _o, S _oFor the distance of submarine target thing, work as S to imaging len _i, S _oSatisfy the thin lens Gauss equation with the imaging len focal distance f

\frac{1}{S_{o}} + \frac{1}{S_{i}} = \frac{1}{f}

The time can obtain image under the combined detection.

In detection process, object distance S _oBe unknown, image distance S _iRelevant with the relative position between imaging len, beam splitter, nonlinear crystal, the scanning optical fiber.According to Gauss's imaging formula, by adjusting image distance S _i, can obtain the combined detection image.By S _i, f can determine object distance S _o, and then can obtain the underwater degree of depth of object.

In the direction of propagation of not considering light, just according to the Gauss's imaging equation in the optical imagery, the light path part of system design can be simplified on the straight line and describe, as shown in Figure 2.

If imaging len just is placed on the water surface, its focal distance f is 72m, image distance S _iBe 180m, promptly from incident optical signal at the plane of incidence of imaging len through beam splitter to nonlinear crystal, and then the distance that the path from nonlinear crystal along unused light arrives image (scanning optic fibre input end plane) is 180m, then according to thin lens Gauss equation, object distance S _oBe 120m, consider that (the seawater refractive index is different in zones of different for the influence of seawater refractive index, refractive index can be determined according to the actual measurement zone), submarine target is about about 80m to the geometric distance of imaging len, and promptly the underwater degree of depth of object is about about 80m.

Claims

1, utilize the method for relevance imaging detecting underwater object, contain and have the following steps:

(1) will be divided into two-beam through beam splitter by the two-photon that tangles that nonlinear crystal produces, and two-beam will be used separately as flashlight and unused light;

(2) with flashlight by imaging convex lens and light filter after directive submarine target thing;

(3) photodetector D is set ₁, collect the reflected signal light that after the object reflection, has carried object information; Scan detector D is set ₂, the unused light behind the segment distance, detector D are freely propagated in collection ₁And D ₂Be complementary;

(4) use scan detector D ₂Optic fibre input end when carrying out dynamic scan the coordinate function of correspondence write down detector D ₁And D ₂The combined detection image;

(5) definition submarine target thing is S to the distance of imaging len _o, the image at place, scanning optic fibre input end plane is S to the distance of lens _i, S _iComprising from the imaging len back side through beam splitter to nonlinear crystal, and then the path from non-linear capable crystal along unused light arrives the distance of the image on scanning optic fibre input end plane, work as S _o, S _iSatisfy the thin lens Gauss equation with the imaging len focal distance f

\frac{1}{S_{o}} + \frac{1}{S_{i}} = \frac{1}{f}

The time can obtain image under the combined detection, this moment is by S _i, f just can calculate object distance S _o, obtain the underwater degree of depth of object.

2, detection method according to claim 1 is characterized in that: in detection process, and object distance S _oBe unknown, image distance S _iRelevant with the relative position between imaging len, beam splitter, nonlinear crystal, the scanning optical fiber, according to Gauss's imaging formula, by adjusting image distance S _i, can obtain the combined detection image, by S _i, f can determine object distance S _o, and then can obtain the underwater degree of depth of object.