CN203561335U

CN203561335U - Flash frequency laser speckle three-dimensional target acquisition system

Info

Publication number: CN203561335U
Application number: CN201320646067.3U
Authority: CN
Inventors: 贺正权; 孔德鹏; 屈恩世; 李育林; 张敏睿; 胡宝文
Original assignee: XiAn Institute of Optics and Precision Mechanics of CAS
Current assignee: XiAn Institute of Optics and Precision Mechanics of CAS
Priority date: 2013-10-18
Filing date: 2013-10-18
Publication date: 2014-04-23
Anticipated expiration: 2023-10-18

Abstract

The utility model relates to a flash laser speckle three-dimensional target acquisition system. The device comprises a synchronous control unit, a speckle generation unit, an image acquisition unit and an image processing unit; the speckle generating unit comprises a pulse light source and a diffraction element and is used for generating a speckle pattern which is randomly distributed and projecting the speckle pattern on a measured object; the synchronous control unit controls the speckle generation unit and the image acquisition unit to work synchronously; the image acquisition unit transmits acquired image data to the image processing unit. The utility model provides a can eliminate the ambient light composition that the information collection is invariable relatively to improve the flicker laser speckle three-dimensional target acquisition system of the SNR of signal.

Description

A kind of frequency laser speckle objective that dodges obtains system

Technical field

The utility model belongs to laser intelligence process field, relates to a kind of target acquisition system, relates in particular to a kind of frequency laser speckle objective that dodges and obtains system.

Background technology

Objective object can be modulated light under illumination condition, and objective obtains technology exactly by light signal is processed, and demodulates the three-dimensional information of object.The method of optical 3-dimensional Target Acquisition is non-cpntact measurement, has speed fast, and the advantage that precision is high can be applicable to the fields such as machine vision, industrial manufacture, three-dimensional modeling and human body attitude tracking.The method that three-dimensional information obtains has initiatively two kinds of light methods and passive smooth method.Initiatively light method is by measured target projective structure light (being the light field that light distribution has certain rule), and passive smooth method is to utilize measured target to natural reflection of light and scattering.Initiatively light method can, by the light of projection specific wavelength and ad hoc structure, be different from mixed and disorderly random surround lighting, therefore, can eliminate the interference of surround lighting.Initiatively light method can be worked under multiple environment light condition, as indoor, at night etc., has reliable operation, adaptable advantage.

Initiatively in optical measurement techniques, light source projects various patterns through optical system, has two kinds of one dimension pattern (as striped, one-dimensional lattice) and two-dimensional patterns (as gridiron pattern and two-dimensional lattice etc.), these patterns normally rule, periodically, pattern be distributed with regularity and repeatability.The mechanism of production of this class pattern is fairly simple, can utilize computer software pattern generation, then by projecting cell, projects away.But the shortcoming of this method is the complex structure of projection system, need to have pattern generation unit (as computing machine) and projecting cell (as projector) two parts, and periodically (on one dimension or two-dimensional directional) pattern can produce parcel problem at solution timing.Therefore, people had proposed again to utilize random speckle pattern afterwards.Random speckle is to project light onto diffractive-optical element (as grating, holographic plate) above by light source (being generally coherent source), and then the far field after diffraction element forms.Hot spot in these speckle pattern is that completely random distributes on locus, therefore, there will not be parcel problem when such speckle pattern is carried out to image processing.And projecting unit only has diffraction optical element, can be integrated together with light source, make structure very simple, can realize miniaturization, blocking.

Existing laser speckle objective obtains technology, can normally work, but in the more intense scene of some natural lightings, surround lighting can produce and disturb active light, and equipment cannot normally be worked under indoor light condition.

Utility model content

In order to solve existing technical matters in background technology, the utility model proposes a kind of frequency laser speckle objective that dodges and obtain system, can effectively raise the signal to noise ratio (S/N ratio) of signal.

The technical solution of the utility model is:

A kind of frequency laser speckle objective that dodges obtains system, and its special character is: comprise synchronous control unit, speckle generation unit, image acquisition units and graphics processing unit;

Above-mentioned speckle generation unit comprises light-pulse generator and diffraction element, in order to produce the speckle pattern of stochastic distribution and to project on testee;

Above-mentioned synchronous control unit control speckle generation unit is synchronoused working with image acquisition units;

Above-mentioned image acquisition units will collect to such an extent that view data passes to graphics processing unit;

The pulse that above-mentioned light-pulse generator is sent is periodic optical pulse;

Above-mentioned image acquisition units comprises CCD camera and attenuator.

The beneficial effects of the utility model are:

The utility model is by modulating active light, makes it with the illumination of glimmering of certain frequency, in photodetector part, also with same frequency, surveys, thereby can remove metastable ambient light interference.Sudden strain of a muscle of the present utility model frequently measuring technique is that light source is modulated, become periodic light pulse signal, at probe portion, also with same frequency, carry out signals collecting, so just can eliminate relatively constant surround lighting composition, thereby the signal to noise ratio (S/N ratio) that improves signal can normally be worked system under various illumination conditions.

Accompanying drawing explanation

Fig. 1 is the utility model system architecture schematic diagram;

Fig. 2 is the utility model speckle generation unit structural representation;

Fig. 3 is the utility model synchronous control signal sequential schematic diagram;

The total trigger pip schematic diagram of Fig. 3 (a) system;

Fig. 3 (b) image acquisition units control signal schematic diagram;

Fig. 3 (c) CCD camera control signal schematic diagram;

Fig. 3 (d) light source control signal schematic diagram;

Fig. 4 surround lighting is removed principle schematic.

Embodiment

Referring to Fig. 1-4, in the system shown in Fig. 1, synchronous control unit ordered pair system by shown in Fig. 3 time is controlled.The total trigger pip of system (Fig. 3 (a)) is that one-period is the pulse train of T.When system is started working, first total trigger pip starts, and starts image acquisition units control signal (Fig. 3 (b)), after time delay τ simultaneously, start CCD camera control signal (Fig. 3 (c)), light source control signal (Fig. 3 (d)) is also started working simultaneously.For the CCD camera itself with synchronizing signal interface, do not need image acquisition units control signal, can be directly with the work of synchronizing signal control CCD camera.

Because CCD camera synchronization control signal and light source control signal start work simultaneously, and their cycle is also identical, so under this working method, the appearance of speckle and image acquisition are synchronously to carry out.The image collecting by filtering, can be removed surround lighting in time domain.

When image acquisition units is carried out imaging to target object, the light field Io on target object is formed by two parts optical superposition, i.e. surround lighting Ie and speckle light Is, as shown in Figure 4.Surround lighting determines by the residing environment light field of target object, and speckle only has speckle generation unit to produce, and then projects on measured target.The intensity I e of environment light field is normally metastable, and speckle light Is is periodically variable after debugging.As previously mentioned, image acquisition units is also to carry out image acquisition with the cycle synchronisation identical with light source.Like this, by the mode of filtering, can remove the composition of surround lighting, and only retain the signal of speckle light.

In actual system, the sensitization dynamic range of CCD camera is limited, when surround lighting in the residing environment of target is too strong, there will be sensitization saturated phenomenon, and in this case, camera cannot be surveyed other light.So under high light environment, needing increases attenuator, surround lighting is decayed, or camera is operated under the state of automatic gain control (AGC).

Because the employing speed of CCD camera is limited, particularly high resolution camera, proportion often only had for tens frame/seconds, and the modulating frequency of light source can reach several KHz.So,, by modulating frequency sampling, be directly unrealistic sometimes.For this problem, can adopt and owe Sampling techniques, be that we can sample by the harmonic frequency of modulating frequency, if modulating frequency is fs, we can be by fs/2, fs/3, fs/4, ... equifrequent is sampled, and that is to say, we sample according to the time cycle integral multiple of modulation of source frequency.

Claims

1. dodge frequency laser speckle objective and obtain a system, it is characterized in that: comprise synchronous control unit, speckle generation unit, image acquisition units and graphics processing unit;

Described speckle generation unit comprises light-pulse generator and diffraction element, in order to produce the speckle pattern of stochastic distribution and to project on testee;

Described synchronous control unit control speckle generation unit is synchronoused working with image acquisition units;

Described image acquisition units will collect to such an extent that view data passes to graphics processing unit.

2. a kind of frequency laser speckle objective that dodges according to claim 1 obtains system, it is characterized in that: the pulse that described light-pulse generator is sent is periodic optical pulse.

3. a kind of frequency laser speckle objective that dodges according to claim 2 obtains system, it is characterized in that: described image acquisition units comprises CCD camera and attenuator.