CN106908445A - Spatial frequency domain imaging device and method based on EO-1 hyperion - Google Patents

Abstract

The invention discloses a space frequency domain imaging device and method based on hyperspectrum. Including the projection part and the imaging part in the box and the installation box, the sample is placed on the sample stage, the projection device of the projection part and the imaging device of the imaging part are all facing the sample; the spatially modulated structured light is irradiated on the sample to be tested, and the hyperspectral The camera scans the reflected light of the sample to obtain a hyperspectral image, adjusts the phase and frequency parameters of the structured light to scan and collect different hyperspectral images, and demodulates the image into a diffuse emission image of the sample to be detected, and then extracts it from the diffuse emission image Obtain the optical characteristic parameter information of the detected sample at continuous wavelengths. The invention can realize the visible-near-infrared hyperspectral detection of the optical characteristic parameters of biological samples, and has the advantages of large imaging area and multiple wavelength information.

Description

Spatial frequency domain imaging device and method based on hyperspectral

technical field

The invention relates to a method and device for detecting optical characteristics of biological tissue, in particular to a hyperspectral-based spatial frequency domain imaging device and method for detecting optical characteristic parameters of biological tissue.

Background technique

The history of human research on light can be traced back to more than 2,000 years ago. Light is not only a carrier of energy and information, but also an effective tool for scientific research. By obtaining and analyzing the optical characteristic parameters of the tested sample, its relevant properties can be obtained and based on this, practical applications such as quality assessment, classification and grading can be carried out. Absorption spectroscopy analysis technology is a typical optical analysis method that is often used, such as visible/near-infrared spectroscopy analysis technology. This type of technology is based on Lambert-Beer's law of absorption, and does not fully consider the scattering of light and biological tissues and the light in tissues. However, biological tissues are often complex and non-uniform high-scattering media. Therefore, traditional absorption spectroscopy analysis techniques are insufficient in detecting quality indicators related to tissue structure, and cannot effectively explain the interaction between light and biological tissues. effect. Therefore, obtaining the light transmission characteristic parameters of biological tissues (such as absorption coefficient, reduced scattering coefficient, etc.) is a key scientific problem that must be solved to expand the depth of the optical properties of the study object.

In recent years, techniques for separating absorption from scattering have attracted considerable attention in the field of biomedical photonics. As emerging methods, space-resolved spectroscopy (SRS) and time-resolved spectroscopy (TRS) combine a variety of traditional visible/near-infrared spectroscopy methods to separate absorption information from scattering information through light propagation models. SRS is to obtain the diffuse reflectance spectrum of the detection point at different distances from the light source, and use the corresponding diffusion model to fit the absorption coefficient and the reduced scattering coefficient. TRS is to measure the flight time of the photon by pulsed laser irradiation, using the corresponding Diffuse model to fit the absorption coefficient and reduced scattering coefficient. According to the different instruments used, SRS can be divided into SRS based on array fiber optic probe, SRS based on monochromatic imaging, hyperspectral spatially resolved imaging (HISR) and spatial frequency domain imaging (SFDI). Among them, compared with SRS of fiber optic probe, SRS based on monochromatic imaging has a larger detection area, while HISR can obtain information of more wavelengths compared with it. The detection range of SRS and HISR based on monochromatic imaging is limited by the diffusion area of point light sources, and the height of the contour cannot be detected synchronously to reduce the influence of the contour on the detection results. SFDI uses spatially modulated illumination sources to study the optical properties of samples in the spatial frequency domain. Since the irradiation light is modulated, the optical characteristic parameter information of samples at different depths can be obtained by changing the spatial frequency of the modulated light. The disadvantage is that the number of detection wavelengths selected by the filter wheel is limited and the adjustment is inconvenient. Although filters can improve this problem, there are still shortcomings if continuous wave spectrum analysis is to be carried out. Therefore, it is meaningful to invent a biological tissue optical characteristic detection device that can not only perform wide-field imaging, but also has certain tomographic detection functions and continuous wavelength information.

Contents of the invention

The object of the present invention is to solve the problems in the above-mentioned background technology and provide a hyperspectral-based spatial frequency domain imaging device and method. By combining spatial frequency domain imaging technology and hyperspectral imaging technology to detect the optical characteristic parameters of biological tissue, it can It satisfies the wide-field detection of optical characteristic parameters of biological samples at visible-near-infrared continuous wavelengths.

The technical scheme that the present invention adopts is as follows:

1. A hyperspectral-based spatial frequency domain imaging device:

The device includes a box and a projection part installed in the box, an imaging part support, a projection part support, an imaging part, a sample stage, a first electric translation stage, a second electric translation stage, a controller and a computer. The bottom of the box is installed with a second Two electric translation stage, sample stage and projection part, the sample is placed on the sample stage, the first electric translation stage is vertically installed on the second electric translation stage, the imaging part support is installed on the first electric translation stage, and the imaging part support is installed There is an imaging part, and the projection part is installed on the support of the projection part. The projection device of the projection part and the imaging device of the imaging part are both facing the sample; a controller and a computer are arranged outside the box, and both the projection part and the imaging part are connected to the computer. The electric translation platform and the second electric translation platform are connected through the controller and the computer.

Both the first electric translation stage and the second electric translation stage can use a combination of an electric cylinder and a slider or a combination of an electric motor, a lead screw and a lead screw nut.

The first electric translation stage and the second electric translation stage are connected to the controller outside the box through a serial port line, and the projection part, imaging part, and controller are respectively connected to the computer outside the box through a video line, a network cable, and a serial port line .

The projection part includes a projector, a projection part installation box and a projection polarizer, the projector installation box is fixedly installed on the top of the projection part bracket, the projector is placed in the projector installation box, and the projection polarizer is installed on the front of the projector lens. In the cylinder of the projector installation box, the included angle between the orientation of the lens of the projector and the vertical direction is less than 5°.

The imaging part includes a visible band spectrum camera, a near-infrared band spectrum camera and two imaging polarizers. The two cameras are fixedly installed on the top of the bracket of the imaging part. The two cameras are located directly above the sample with the lens end facing down. The two camera lenses Imaging polarizers are arranged directly in front of the end, and the polarization directions of the imaging polarizers and the projection polarizers are perpendicular to each other.

The visible band spectrum camera, near-infrared band spectrum camera and two imaging polarizers of the present invention constitute a hyperspectral camera.

The projector projects spatially modulated structured light onto the sample, switches the visible band spectrum camera or the near-infrared band spectrum camera through the first motorized translation stage, and drives the imaging part to move above the sample through the second motorized translation stage to realize the accurate detection of the sample. Scanning imaging of the surface to obtain a hyperspectral image of the sample surface.

Spatially modulated structured light refers to sinusoidal grayscale spatially structured light.

Both sides of the projector installation box are provided with horizontal parallel long grooves, and both sides of the projection part support are provided with vertical parallel long grooves, and the projector installation box and the parallel long grooves of the projection part support are connected by threads .

The top side wall of the bracket of the imaging part is provided with four vertical parallel long slots, which are used to facilitate the adjustment of the installation height of the visible band spectrum camera and the near infrared band spectrum camera.

2. A hyperspectral-based spatial frequency domain imaging method:

The spatially modulated structured light is irradiated on the tested sample to produce reflection, the hyperspectral camera scans the reflected light of the tested sample to obtain a hyperspectral image, and adjusts the phase and frequency parameters of the structured light to perform a series of scanning acquisitions to obtain the continuous wavelength corresponding Different from the hyperspectral image, the hyperspectral image is demodulated into the diffuse emission image of the detected sample, and then the optical characteristic parameter information of the detected sample at continuous wavelengths (absorption coefficient μ _a and reduced scattering Coefficient μ' _s ).

The diffuse emission image acquisition process of the detected sample is specifically:

1) First use a reference whiteboard instead of the tested sample to place on the sample stage, and sequentially project structured light with sinusoidal grayscale patterns of different spatial frequencies to the reference whiteboard through the projector, and after each projection, pass through the visible band spectrum camera or The near-infrared band spectral camera scans the reference whiteboard to collect visible light images or near-infrared images of the reference whiteboard;

2) Place the sample to be tested on the sample stage, and then sequentially project structured light with sinusoidal grayscale patterns of different spatial frequencies to the reference whiteboard through the projector. The camera scans the sample to be tested, and collects visible light images or near-infrared images of the sample to be tested;

3) Turn off the projector, and scan the detected sample through a visible band spectral camera or a near-infrared spectral camera to collect dark field images;

4) Select the region of interest in the image, and demodulate the image obtained from the tested sample according to the image obtained from the reference whiteboard to obtain the diffuse emission image of the tested sample.

The innovation of the present invention is to improve the hyperspectral imaging technology to realize spatial frequency domain imaging, replace the line light source with the spatially structured light projected by the projector, realize the wide-field detection of the sample surface by moving the camera, and realize the optical characteristics of the sample through the spatial frequency imaging technology Detection of parameters at continuous wavelengths in the visible and near infrared.

The beneficial effects of the present invention are:

The device of the present invention combines spatial frequency domain imaging technology with hyperspectral imaging technology, can realize wide-field detection of optical characteristic parameters (large imaging area) of biological samples at visible-near-infrared continuous wavelengths, and has a certain tomographic detection function , capable of obtaining rich spectral information at continuous wavelengths. Compared with the existing spatial frequency domain imaging technology, its wavelength information is richer and the cost is lower.

Description of drawings

Fig. 1 is a schematic diagram of the device of the present invention;

Fig. 2 is a sectional view of the installation box 102 of the projection part;

FIG. 3 is a schematic diagram of the bracket 6 of the imaging part.

In the figure: 0, cabinet, 1, projection part, 2, imaging part, 3, sample stage, 4, projection part support, 5, sample, 6, imaging part support, 7, first electric translation stage, 8, second 2. Electric translation platform, 9. Controller, 10. Computer, 101. Projector, 102. Installation box for projection part, 103. Projection polarizer, 201. Visible band spectrum camera, 202. Near infrared band spectrum camera, 203. Imaging polarizer.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

As shown in Figure 1, the present invention includes a box body 0 and a projection part 1 installed in the box, an imaging part support 6, a projection part support 4, an imaging part 2, a sample stage 3, a first electric translation stage 7, a second electric translation Stage 8, controller 9 and computer 10, second electric translation platform 8, sample stage 3 and projection part 1 are installed on the bottom of box body 0, sample 5 is placed on sample stage 3, first electric translation stage 7 is vertically installed on On the second electric translation stage 8, the imaging part support 6 is installed on the first electric translation stage 7, the imaging part 2 through hyperspectral image collection is installed on the imaging part support 6, and the projection part 1 is installed on the projection part support 4 , the projection device of the projection part 1 and the imaging device of the imaging part 2 are all facing the sample 5; a controller 9 and a computer 10 are arranged outside the cabinet 0, and the first electric translation stage 7 and the second electric translation stage 8 are connected to the outside of the cabinet 0 The controller 9 is connected to each other through a serial cable, and the projection part 1, the imaging part 2, and the controller 9 are connected to the computer 10 outside the cabinet 0 through a video cable, a network cable, and a serial cable, respectively.

As shown in Figure 1, the projection part 1 comprises a projector 101, a projection part installation box 102 and a projection polarizer 103, the projector installation box 102 is fixedly installed on the top of the projection part support 4, and the projector 101 is placed in the projector installation box 102 , ensure that the projector lens faces the cylinder outlet of the projector installation box 102 and faces the sample 5, and the projection polarizer 103 is installed in the cylinder of the projector installation box 102 directly in front of the lens of the projector 101, and is screwed through the sleeve connecting thread , the angle between the orientation of the lens of the projector 101 and the vertical direction is less than 5°, so as to ensure that the projected pattern is irradiated onto the sample stage 3 .

As shown in Figure 1, the imaging part 2 includes a visible band spectrum camera 201, a near-infrared band spectrum camera 202 and two imaging polarizers 203, and the two cameras are fixedly installed on the top of the imaging part support 4, and the two cameras are located directly above the sample 5 And the lens end faces down, and the front of the two camera lens ends is equipped with imaging polarizer 203, and two imaging polarizers 203 are fixedly installed in the through holes of the two fixing plates of the imaging part support 6, and the imaging polarizer 203 and the projection polarizer The polarization direction of the plate 103 is perpendicular to eliminate specular reflection light.

The projector 101 projects spatially modulated structured light onto the sample 5, switches the visible band spectrum camera 201 or the near-infrared band spectrum camera 202 through the first electric translation stage 7, and drives the imaging part 2 on the sample 5 through the second electric translation stage 8 Move upward to realize the scanning imaging of the surface of the sample 5, and obtain the hyperspectral image of the surface of the sample 5.

As shown in Figure 2, both sides of the projector installation box 102 are provided with horizontal parallel long grooves, and both sides of the projection part support 4 are provided with vertical parallel long grooves, and the parallel surfaces of the projector installation box 102 and the projection part support 4 The long grooves are connected by threads to conveniently adjust the installation angle and height of the projection part 1 .

As shown in FIG. 3 , there are four vertical parallel long slots on the top side wall of the imaging part support 6 , and the four parallel long slots are used for conveniently adjusting the installation heights of the visible band spectrum camera 201 and the near infrared band spectrum camera 202 .

The specific implementation imaging process of the present invention is:

1) Firstly, a reference whiteboard is used instead of the sample to be tested and placed on the sample stage 3, and the projector 101 sequentially projects structured light with sinusoidal grayscale patterns of different spatial frequencies to the reference whiteboard, and passes through the visible band spectrum after each projection. The camera 201 or the near-infrared band spectrum camera 202 scans the reference whiteboard and collects a visible light image or a near-infrared image of the reference whiteboard;

2) Place the sample to be tested on the sample stage 3, and then sequentially project structured light with sinusoidal grayscale patterns of different spatial frequencies to the reference whiteboard through the projector 101, and after each projection, pass through the visible band spectrum camera 201 or near The infrared band spectrum camera 202 scans the sample to be tested, and collects a visible light image or a near-infrared image of the sample to be tested;

3) Turn off the projector 101, and scan the detected sample through the visible band spectrum camera 201 or the near-infrared band spectrum camera 202 to collect dark field images;

4) Select the region of interest in the image, and demodulate the image obtained from the tested sample according to the image obtained from the reference whiteboard to obtain the diffuse emission image of the tested sample.

5) Extract the information of the optical characteristic parameters of the detected sample at continuous wavelengths from the diffuse emission image, including the absorption coefficient μ _a and the reduced scattering coefficient μ' _s .

Claims (7)

1. a kind of spatial frequency domain imaging device based on EO-1 hyperion, it is characterised in that：Including in casing (0) and installation casing It is projection section (1), imaging moiety support (6), projection section support (4), imaging moiety (2), sample stage (3), first electronic flat Moving stage (7), the second motorized precision translation stage (8), controller (9) and computer (10), it is electronic that the bottom in casing (0) is provided with second Translation stage (8), sample stage (3) and projection section (1), place sample (5) on sample stage (3), the first motorized precision translation stage (7) is vertical On the second motorized precision translation stage (8), imaging moiety support (6), imaging moiety are installed on the first motorized precision translation stage (7) Imaging moiety (2) is installed on support (6), projection section (1), the throwing of projection section (1) are installed on projection section support (4) The imaging device of shadow equipment and imaging moiety (2) is towards sample (5)；Casing (0) is externally provided with controller (9) and computer (10), projection section (1) and imaging moiety (2) are all connected to computer (10), the first motorized precision translation stage (7) and second electronic flat Moving stage (8) via controller (9) and computer (10) are connected.

2. a kind of spatial frequency domain imaging device based on EO-1 hyperion according to claim 1, it is characterised in that：The projection Partly (1) installs case (102) and projection polarization piece (103) including projecting apparatus (101), projection section, and projecting apparatus installs case (102) Projection section support (4) top is fixedly mounted on, projecting apparatus (101) is placed on projecting apparatus and installs in case (102), projection polarization piece (103) projecting apparatus immediately ahead of projecting apparatus (101) camera lens is installed in the cylinder of case (102), the camera lens of projecting apparatus (101) Angle between direction and vertical direction is less than 5 °；

The imaging moiety (2) including visible waveband spectrum camera (201), near infrared band spectrum camera (202) and two pieces into As polarizer (203), two cameras are fixedly mounted on imaging moiety support (4) top, and two cameras are located at directly over sample (5) And camera end is down, be equipped with imaging polarization piece (203) immediately ahead of two camera lens ends, imaging polarization piece (203) with The polarization direction of projection polarization piece (103) is perpendicular.

3. a kind of spatial frequency domain imaging device based on EO-1 hyperion according to claim 2, it is characterised in that：The projection Instrument (101) projects the structure light of spatial modulation to sample (5), and visible waveband light is switched by the first motorized precision translation stage (7) Spectrum camera (201) or near infrared band spectrum camera (202), imaging moiety (2) is driven in sample by the second motorized precision translation stage (8) Product (5) top is mobile, realizes the scanning imagery to sample (5) surface, obtains the high spectrum image on sample (5) surface.

4. a kind of spatial frequency domain imaging device based on EO-1 hyperion according to claim 1, it is characterised in that：Described throwing Shadow instrument installs case (102) both sides and is provided with horizontal parallel elongated slot, and the both sides of projection section support (4) are provided with vertical parallel long Groove, projecting apparatus is installed and is connected through a screw thread between case (102) and the parallel elongated slot of projection section support (4).

5. a kind of spatial frequency domain imaging device based on EO-1 hyperion according to claim 1, it is characterised in that：It is described into As portion support (6) top sidewall is provided with four vertical parallel elongated slots, four parallel elongated slots are used for convenient regulation visible waveband The setting height(from bottom) of spectrum camera (201) and near infrared band spectrum camera (202).

6. a kind of spatial frequency domain imaging method based on EO-1 hyperion of any methods describeds of claim 1-5, its feature are applied to It is：Structure light after spatial modulation is irradiated to and reflection is produced on detected sample, and EO-1 hyperion camera scanning is detected sample Reflected light obtains a panel height spectrum picture, and adjusting the phase and frequency parameter of structure light carries out a series of scanning collections acquisitions continuously The corresponding different high spectrum images of wavelength, by high spectrum image through the unrestrained transmitting image that image demodulation is detected sample, then from Extract to obtain in unrestrained transmitting image and be detected optical property parameter information of the sample under continuous wavelength.

7. a kind of spatial frequency domain imaging method based on EO-1 hyperion according to claim 6, it is characterised in that：It is described tested The unrestrained transmitting image acquisition process of test sample product is specially：

1) first replaced with reference blank being detected sample and be placed on sample stage (3), by projecting apparatus (101) to reference blank according to The secondary structure light with sinusoidal greyscale pattern for projecting different space frequency, passes through visible waveband spectrum camera after projection every time Or near infrared band spectrum camera (202) scanning reference blank collects the visible images of reference blank or near (201) Infrared image；

2) detected sample is placed on sample stage (3), then difference is projected by projecting apparatus (101) successively to reference blank The structure light with sinusoidal greyscale pattern of spatial frequency, every time by visible waveband spectrum camera (201) or near after projection Infrared band spectrum camera (202) scanning is detected sample, collects the visible images or near-infrared figure of detected sample Picture；

3) projecting apparatus (101) is closed, is swept by visible waveband spectrum camera (201) or near infrared band spectrum camera (202) Retouch detected sample collection darkfield image；

4) interesting image regions are chosen, the image obtained by being detected sample is carried out according to the image obtained by reference blank Demodulation obtains the unrestrained transmitting image for being detected sample.