CN1097724C - Raster and prism combined ultraspectrum method for measuring image - Google Patents

Abstract

The invention belongs to the technical field of spectrum measurement and relates to a method for measuring hyperspectral images of objects. The invention simultaneously uses a one-dimensional grating and a prism to encode the image of the object in space and spectrum, uses a detector to collect data on the encoded image, and restores the hyperspectral image of the object through digital subtraction. The invention can measure stationary, dynamic and weak radiation objects with high spectral and spatial resolution. The corresponding instrument has the characteristics of simple structure, good stability, and easy use, and can be used for scientific research, resource survey, environmental monitoring, target identification, etc. field.

Description

Grating and prism combined ultraspectrum method for measuring image

Technical field:

The invention belongs to the spectral measurement methods field, relate to a kind of method of utilizing grating and prism multiple measurement object HYPERSPECTRAL IMAGERY.

Background technology:

HYPERSPECTRAL IMAGERY means the 3-D view of being described by the one dimension wavelength of " continuously " and two-dimensional space, and for example object is through formed picture behind the optical imaging system.

Begin to develop the method and the technology of Measuring Object HYPERSPECTRAL IMAGERY in the world from early eighties.Recent two decades comes, and used technical method mainly is the imaging spectral technology method that imaging technique is combined with spectral technique on the engineering.In imaging spectral technology, preceding optical system with object image-forming on the entrance slit of spectrometer; Spectrometer will separate by wavelength by the optical radiation that slit enters; Push away the HYPERSPECTRAL IMAGERY of sweeping Measuring Object by linear array detector sweeping or planar array detector.In order to alleviate the quality of imaging spectral instrument, the eighties art begins one's study in the world and substitutes the imaging spectral technology of spectroscopy with interferometry.Because must come the implementation space to differentiate by slit, imaging spectral technology exists two limitation: (1) photon effective rate of utilization be very low, it is very difficult to survey weak radiation; (2) the only suitable HYPERSPECTRAL IMAGERY of measuring stationary body.

Realize ultraphotic spectrometry, just must adopt full visual field optical system weak radiation and dynamic object.The early 1990s, a kind of full visual field ultraphotic spectrometry method---spectrum chromatography method that light splitting technology and tomography thought are combined has been proposed in the world.The spectrum chromatography method at first uses a kind of beam splitter (prism or grating) to produce one group of tomographic projection of HYPERSPECTRAL IMAGERY; By this tomographic projection sequence,, reconstruct the HYPERSPECTRAL IMAGERY of object then by data inversion.According to the difference that forms tomographic projection sequence mode, the spectrum tomography is divided into two kinds.First kind, adopt prism as beam splitter, by rotate whole optical system (Opt.Eng.32 around optical axis, (1993) 3133～3138) or change prism (Proc.SPIE.Vol.1843, (1991) 315～322) produce several tomographic projections, be used to measure weak radiation stationary state object, major defect is: " commentaries on classics systems approach " requires very high to rotational stabilization; It is very high to the performance requirement of prism group " to change prism method ", and uses complicated.Second kind, adopt two-dimentional transmission grating as beam splitter, two-way diffraction effect by two-dimentional transmission grating produces a plurality of tomographic projections (Opt.Lett.16 (16) simultaneously, 1277～1279 (1991), Appl.Opt.36 (16), 3694～3698 (1997)), be mainly used in and survey narrow wavestrip, dynamic object that resolution requirement is not high.The spectrum tomography, because number reason relation is complicated between tomographic projection sequence and the original HYPERSPECTRAL IMAGERY, so need just to reconstruct the HYPERSPECTRAL IMAGERY of object by repeatedly algebraically iteration or complex transformations, and the reconstruct HYPERSPECTRAL IMAGERY presents very strong " smoothly " effect, therefore, be not suitable for measuring the more careful space and the object of spectral composition are arranged.

In order to overcome existing imaging spectrum method and the existing problem of spectrum chromatography method that only adopts grating or prism, the objective of the invention is to adopt simultaneously the combination of grating and prism, a kind of method that can measure the HYPERSPECTRAL IMAGERY of stationary state object, dynamic object and weak radiation object with high spectrum and spatial resolution is provided.

Summary of the invention:

Method and step that the present invention measures HYPERSPECTRAL IMAGERY are as follows:

(1) at first, use one-dimensional grating, the picture by the object that object lens obtained is carried out space encoding, the grating constant of one-dimensional grating is by required spatial resolution decision;

(2) secondly, it is optical spectrum encoded to use prism that the space encoding image is carried out, and in order to simplify the number reason relation between space and optical spectrum encoded image and the homologue body image, regulates prism, and the dispersion direction of prism is paralleled with the groove direction of grating;

(3) with grating each other on the plane of object-image conjugate, use detector to finish data acquisition, and the view data of being gathered be sent in the computing machine by lead space and optical spectrum encoded image;

(4) computing machine concerns (see figure 2) according to the number reason between object picture and its coded image, is set out by space and optical spectrum encoded image, by the digital subtraction computing, restores the HYPERSPECTRAL IMAGERY of object.

The advantage and the good effect of grating provided by the invention and prism combined ultraspectrum method for measuring image are as follows:

(1) the invention provides a kind of grating and prism of using simultaneously HYPERSPECTRAL IMAGERY is carried out Methods for Coding.It to the result of HYPERSPECTRAL IMAGERY coding as shown in Figure 2.In Fig. 2, the light signal that is collected along each pixel of x directional detector in the interval 1 is the stack of the different spectrum of same matter-element, therefore, via the algebraically subtraction, just can try to achieve the spectrogram of corresponding matter-element; Though interval 2 and interval 1 partially overlaps, because interval 1 spectroscopic data is known, so, still can obtain the spectrogram of corresponding matter-element by the algebraically subtraction; Below analogize.By said process as seen, the inventive method makes by a width of cloth coded image, through the algebraically subtraction, just can accurately restore the HYPERSPECTRAL IMAGERY of object, thus the spectrum of HYPERSPECTRAL IMAGERY and palinspastic reconstruction precision height.

Fig. 3 is used for a tomographic projection of reconstruct HYPERSPECTRAL IMAGERY in the spectrum tomography.Apparent by Fig. 3, the light signal that the detector pixel is collected, it is the stack of the different spectral radiance of adjacent matter-element, this makes between its corresponding HYPERSPECTRAL IMAGERY of tomographic projection sequence that number reason relation is complicated, needs just can be reconstructed through repeatedly algebraically iteration or complex transformations by the some width of cloth tomographic projections HYPERSPECTRAL IMAGERY of object.So, spectrum tomography restructuring procedure complexity, time-consuming, precision is not high.

Therefore, the present invention has overcome spectrum chromatography spectrum and the not high problem of spatial resolution.

(2) because the present invention adopts the combined type of grating and prism, make that the HYPERSPECTRAL IMAGERY measuring system is full visual field, so photon effective rate of utilization height, can measure weak radiation object with high spectrum and spatial resolution, thereby overcome the problem that imaging spectrum method and spectrum chromatography method can not be measured weak radiation object with high spectrum and spatial resolution.

(3) can obtain simultaneously to be used to restore object HYPERSPECTRAL IMAGERY required whole spaces and spectral information owing to the present invention, thus the HYPERSPECTRAL IMAGERY of energy measurement dynamic object, thus overcome the not problem of energy measurement dynamic object HYPERSPECTRAL IMAGERY of imaging spectrum method.

(4) the inventive method both can have been measured the HYPERSPECTRAL IMAGERY of weak radiation object, can measure the HYPERSPECTRAL IMAGERY of dynamic object again, had overcome the problem that a kind of structure of spectrum chromatography can only be measured a type objects HYPERSPECTRAL IMAGERY.

(5) compare with the imaging spectrum spectrum tomographic system of unifying, have simple in structure, good stability, characteristic such as easy to use by the HYPERSPECTRAL IMAGERY measuring instrument of manufacturing of the present invention.

Description of drawings: Fig. 1 is a kind of embodiment principle schematic of the present invention.Fig. 2 is the synoptic diagram that the technology of the present invention is encoded to HYPERSPECTRAL IMAGERY.Fig. 3 is the synoptic diagram that the spectrum chromatographic technique is encoded to HYPERSPECTRAL IMAGERY.

Embodiment:

A kind of embodiment of the present invention:

Utilize a kind of HYPERSPECTRAL IMAGERY measurement mechanism that the inventive method makes as shown in Figure 1.This device partly is made of object lens 1, one-dimensional grating 2, lens 3, prism 4, lens 5, detector 6 and computing machine 7 etc.Wherein, one-dimensional grating 2 adopts amplitude grating; Lens 3 adopt the collimation camera lens; Prism 4 adopts dispersing prism, and also available one-dimensional grating substitutes dispersing prism; Lens 5 adopt collective lens; Detector 6 adopts planar array detector.One-dimensional grating 2 is positioned on the image planes of object lens 1: the front focal plane of lens 3 and one-dimensional grating 2 coincide; Place prism 4 between lens 3 and lens 5, the dispersion direction of prism is parallel with the groove direction of grating; The test surface of detector 6 overlaps with the back focal plane of lens 5; Detector 6 links to each other with computing machine 7 through lead.The grating constant of one-dimensional grating 2 is determined according to sampling thheorem by required spatial resolution.

Object lens 1 on one-dimensional grating 2, form the HYPERSPECTRAL IMAGERY that a width of cloth is described by continuous one dimension wavelength and two-dimensional space with object image-forming.One-dimensional grating 2 carries out space encoding to this HYPERSPECTRAL IMAGERY.Lens 3 will be directional light through the HYPERSPECTRAL IMAGERY collimation of one-dimensional grating 2 space encodings.The character that prism 4 becomes with optical wavelength according to its refractive index is carried out optical spectrum encoded to each directional light.Lens 5 converge at directional light on the test surface of detector 6, form a width of cloth space and the optical spectrum encoded image of object HYPERSPECTRAL IMAGERY.6 pairs of spaces of detector and optical spectrum encoded image carry out data acquisition, and pass to computing machine 7 by lead.Computing machine 7 carries out digital inverting according to the spectrum and the space encoding rule of coded image, restores the HYPERSPECTRAL IMAGERY of object.

Claims (1)

1. the method for grating and prism combined Measuring Object HYPERSPECTRAL IMAGERY, its content and measuring process are as follows:

(1) at first, use one-dimensional grating, the picture by the object that object lens obtained is carried out space encoding;

(2) secondly, it is optical spectrum encoded to use prism that the space encoding image is carried out, and regulates prism, and the dispersion direction of prism is paralleled with the groove direction of grating;

(3) with grating each other on the plane of object-image conjugate, use detector to finish data acquisition, and the view data of being gathered be sent in the computing machine by lead space and optical spectrum encoded image;

(4) computing machine is set out by space and optical spectrum encoded image according to the number reason relation between object picture and its coded image, after the digital subtracting computing, restores the HYPERSPECTRAL IMAGERY of object.

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