US20160313177A1 - Near-field terahertz imager - Google Patents
Near-field terahertz imager Download PDFInfo
- Publication number
- US20160313177A1 US20160313177A1 US14/920,373 US201514920373A US2016313177A1 US 20160313177 A1 US20160313177 A1 US 20160313177A1 US 201514920373 A US201514920373 A US 201514920373A US 2016313177 A1 US2016313177 A1 US 2016313177A1
- Authority
- US
- United States
- Prior art keywords
- oscillator
- circuit
- imager
- pixel
- transmission line
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000005540 biological transmission Effects 0.000 claims abstract description 41
- 239000011159 matrix material Substances 0.000 claims abstract description 16
- 238000003384 imaging method Methods 0.000 claims description 11
- 239000004065 semiconductor Substances 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- 239000012212 insulator Substances 0.000 claims description 2
- 230000001939 inductive effect Effects 0.000 claims 1
- 239000000463 material Substances 0.000 description 8
- 238000001514 detection method Methods 0.000 description 5
- 238000001465 metallisation Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 3
- 230000010355 oscillation Effects 0.000 description 3
- 239000002184 metal Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 230000005469 synchrotron radiation Effects 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 230000000903 blocking effect Effects 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 230000001427 coherent effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 239000003989 dielectric material Substances 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/4228—Photometry, e.g. photographic exposure meter using electric radiation detectors arrangements with two or more detectors, e.g. for sensitivity compensation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J1/00—Photometry, e.g. photographic exposure meter
- G01J1/42—Photometry, e.g. photographic exposure meter using electric radiation detectors
- G01J1/44—Electric circuits
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K3/00—Circuits for generating electric pulses; Monostable, bistable or multistable circuits
- H03K3/02—Generators characterised by the type of circuit or by the means used for producing pulses
- H03K3/027—Generators characterised by the type of circuit or by the means used for producing pulses by the use of logic circuits, with internal or external positive feedback
- H03K3/03—Astable circuits
- H03K3/0315—Ring oscillators
Definitions
- the present disclosure relates to high frequency imagers, for example terahertz imagers, formed from a pixel matrix.
- Terahertz imagers are devices adapted to capture the image of a scene based on terahertz waves, i.e., waves having a frequency that is for example comprised between 0.3 and 3 THz.
- a conventional imager such as disclosed in the U.S. Patent Application Publication No. 2014/070103 of the applicant includes a terahertz waves emitter for illuminating a scene to be imaged, and a sensor made of a pixel matrix that receives terahertz waves from the scene.
- Terahertz imagers are used in a large number of applications in which it is wished to see through some materials of a scene.
- Terahertz waves penetrate a large number of dielectric materials and non-polar liquids, are absorbed by water and are almost entirely reflected by metals.
- Terahertz imagers are in particular used in security scanners in airports to see through the clothes of a person or through luggage so as to detect metallic objects for example.
- FIG. 1 is a reproduction of FIG. 1 of U.S. Patent Application Publication No. 2014/070103.
- the sensor 1 includes a matrix 3 of pixels 5 adapted to capture terahertz waves.
- a row decoder 7 receives a row selection signal 9 that indicates which row is to be read and provides to the lines of the matrix 3 a corresponding control signal 11 .
- the pixel matrix 3 provides output signals 13 for each column of the matrix.
- the output signals 13 are coupled to an output block 15 that selects and controls each column.
- the reading of the columns is controlled by a column decoder 17 coupled to the output block 15 and, in this example, the columns are read the one after the other.
- the output block 15 provides an output signal 19 representing the value of the pixel 5 of the selected row and column.
- the output signal 19 is amplified and coupled to an analog to digital converter 21 .
- this signal is combined with a reference terahertz signal provided by an oscillator 23 .
- the oscillator 23 is disposed outside of the matrix 3 and provides a same terahertz signal to a large number of pixels or to all the pixels of the sensor 1 .
- This oscillator 23 is preferably coupled with a terahertz emitter, not shown, illuminating the scene to be analyzed.
- FIG. 2 is a reproduction of FIG. 3 of US application N°2014/070103 and illustrates an example of one pixel 5 of the sensor 1 .
- the pixel 5 comprises a detecting antenna 25 and a detection circuit 27 formed, in this example, of two N-MOS transistors 29 , the gates of which are biased at a potential V gate .
- the antenna is coupled to the oscillator 23 shown in FIG. 1 and to the detection circuit 27 .
- the output of the detection circuit 27 is coupled to a row and column selection circuit 31 .
- the selection circuit 31 is controlled by a signal R SEL provided by the row decoder 7 of the sensor 1 and by a signal C SEL provided by the column decoder 17 of the sensor 1 .
- the analog output signal 19 representing the value of the pixel 5 is available at a node COL OUT that is coupled to the converter 21 ( FIG. 1 ) of the sensor 1 .
- FIG. 3 is a reproduction of FIG. 5 of US application N°2014/070103 representing an example of a frequency oscillation circuit 33 of a terahertz imager.
- the circuit 33 comprises a ring oscillator made of an odd number N of inverters, three in this example.
- Each inverter includes a NMOS transistor 35 the drain of which is coupled to a node 37 and the source of which is coupled to ground.
- Each node 37 is coupled through an inductor 39 to the gate of the next transistor 35 , the inductors 39 having a same inductance value.
- Each node 37 is further coupled to a summation node 41 through an inductor 43 , the inductors 43 all having the same inductance value.
- the summation node 41 is coupled to a DC voltage source 45 via an inductor 47 and to an output node 49 of emitter 33 via an inductor 51 . As shown, the output node 49 can be grounded, for example through a resistor 53 .
- the signal generated by the ring oscillator has a fundamental sinusoidal component of frequency F and harmonic sinusoidal components one of which has a frequency N*F.
- the value of each inductor 43 is selected to implement a band-pass filter centered on the frequency N*F, and an output signal having a frequency f L0 equal to N*F is available at the output node 49 of the emitter 33 that is coupled to a terahertz emission antenna.
- FIG. 4 is a partial reproduction of FIG. 8 of US application N°2014/070103 and schematically illustrates an example implementation of the frequency oscillation circuit 33 as disclosed in connection with FIG. 3 , but with five inverters instead of three.
- each inductor 39 , 43 , 51 is implemented as a transmission line.
- the terahertz imager disclosed in connection with FIGS. 1-4 is a far-field imager provided for seeing through some materials of voluminous objects, seen at a far distance from the object, having sizes greater than 10 cm, preferably greater than 1 meter.
- the resolution of an image obtained with a far-field imager is at best of about the operating wavelength of the imager, i.e., 1 mm at a frequency of 300 GHz and 0.1 nm at a frequency of 3 THz.
- To improve the spatial resolution of a far-field imager it is possible to increase the operating frequency of the imager. However, this raises various problems.
- a far-field terahertz imager is not adapted to obtaining an image having a resolution in the order of tenths of a micrometer.
- Near-field terahertz imagers provide an image of an object to be analyzed with a resolution in the order of tenths of a micrometer.
- these imagers are complex to implement, in particular due to the fact that they use terahertz emission sources such as coherent synchrotron radiations, and optical systems such as elliptical mirrors.
- terahertz emission sources such as coherent synchrotron radiations, and optical systems such as elliptical mirrors.
- An example of such a near-field imager is disclosed in the article “THz near-field imaging of biological tissues employing synchrotron radiation” of Shade et al., published in 2005 in Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX, 46.
- an embodiment provides a high frequency imager comprising a pixel matrix, each pixel comprising: a high frequency oscillator; a transmission line positioned at a distance from an active surface of the imager smaller than the operating wavelength of the oscillator, a first end of the line being coupled to the oscillator; and a read circuit coupled to a second end of the line.
- the read circuit of each pixel provides a signal representative of the impedance of the transmission line.
- the oscillator of each pixel comprises second transmission lines.
- a layer adapted to block the propagation of the high frequency waves covers at least the second lines.
- the read circuit of a pixel provides a signal representative of the frequency of the oscillator of the pixel.
- the transmission lines are of the microstrip type.
- the imager is adapted to operate at a frequency selected in a range of 0.3 to 3 THz.
- FIG. 1 is a reproduction of FIG. 1 of US patent application N°2014/070103 schematically representing an example of a terahertz imager sensor;
- FIG. 2 is a reproduction of FIG. 3 of US patent application N°2014/070103 schematically representing an example of a pixel of the sensor of FIG. 1 ;
- FIG. 3 is a reproduction of FIG. 5 of US patent application N°2014/070103 schematically illustrating an example of terahertz frequency oscillation circuit
- FIG. 4 is a reproduction of FIG. 8 of US patent application N°2014/070103 schematically representing an example of implementation of the circuit of FIG. 3 ;
- FIG. 5 is a schematic plan view representing a portion of the pixels of a terahertz imager according to an embodiment of the present disclosure
- FIG. 6 is a cross-sectional view in a plane AA of FIG. 5 and represents a transmission line of the imager;
- FIG. 7 is a cross-sectional view in a plane BB of FIG. 5 and represents a shielded transmission line of the imager.
- FIG. 5 is a schematic top view of an embodiment of a terahertz imager, only a portion of the imager being shown in this figure.
- the imager comprises a matrix 61 of pixels 63 , three pixels of a column of the matrix 61 being shown in FIG. 5 .
- Each pixel comprises an oscillator, for example such as disclosed in connection with FIGS. 3 and 4 , a read circuit 65 and a transmission line 67 .
- An end of the transmission line 67 is coupled to the node 41 of oscillator 33 and the other end is coupled to the read circuit 65 .
- the read circuit of each pixel is adapted to provide a signal representative of the impedance value of line 67 .
- the read circuit of each pixel is coupled to a line and column selection circuit (not shown) controlled by a line decoder and a column decoder (not shown).
- the oscillator 33 and in some embodiments the detection circuit 65 of each pixel 63 are shielded by a shielding layer 71 , for example a metal layer, blocking the propagation of high frequency waves.
- the oscillator 33 of each pixel is biased by a DC voltage source coupled to the transmission line 67 , for example through the detection circuit 65 of the pixel.
- the oscillator 33 thus provides a terahertz signal having a frequency f and a wavelength ⁇ to the transmission line 67 .
- FIGS. 6 and 7 are respectively a cross-sectional view in a plane AA of FIG. 5 and a cross-sectional view in a plane BB of FIG. 5 .
- FIG. 6 shows three transmission lines 67 of three pixels 63 of the imager of FIG. 5 .
- the transmission lines 67 are formed in metallization levels buried in an insulating layer 73 laying on a semiconductor support 75 .
- Each transmission line comprises a microstrip 77 above a conductive band 79 forming a ground plane.
- the microstrip 77 of each transmission line 67 is covered by an insulating layer having a thickness smaller than A and preferably smaller than 0.1 ⁇ , where ⁇ is the wavelength of the signal of the oscillator coupled to the line.
- An object 81 to be analyzed is arranged against the upper face or active face of the pixel matrix of the imager.
- the object may include a plurality of materials having different dielectric constants and present inhomogeneities of effective dielectric constant.
- terahertz fields radiate from the microstrip 77 to the ground plane 79 , as shown by dotted lines for the right-hand pixel of FIG. 6 , and a part of the fields leaks outside of the imager elements.
- These terahertz fields penetrate a superficial layer of the object 81 to be analyzed.
- analysis depth designates the thickness of the superficial layer of the object in which these terahertz waves penetrate.
- the analysis depth is in the order of several wave lengths ⁇ , for example in the range to 3 ⁇ , i.e., 0.1 to 0.3 mm if the frequency f is equal to 3 THz, and from 1 to 3 mm if the frequency f is equal to 300 GHz.
- the impedance of a transmission line 67 depends upon the effective dielectric constant of the imager elements and of the material of object 81 that is positioned over this line and thus will be different for the two pixels arranged on the right in FIG. 6 , which are positioned under an inhomogeneity 83 , and for the pixel arranged on the left of FIG. 6 .
- An image of the dielectric constants of the material of the upper layer of the object 81 is thus obtained from the set of output signals of the pixels of the imager.
- the resolution of the imager thus corresponds to the dimensions of its pixels. For example, in the case of an oscillator 33 with five inverters providing a signal at 600 GHz, each pixel can have lateral dimensions of 20 to 50 ⁇ m.
- a characteristic of the above disclosed pixels is that the transmission line 67 of each pixel serves as an emitter of terahertz waves for illuminating a portion of an object to be analyzed and is also used as a detector to capture a signal associated with the effective dielectric constant of this portion.
- the semiconductor support 75 is a bulk silicon substrate or a SOI type (“Silicon On Insulator”) substrate in which are formed the electronic components of the imager, in particular the transistors of the pixels.
- This support is covered with metallization levels of an interconnection structure of the electronic components formed in the semiconductive support.
- the microstrip 77 and the ground planes 79 of the transmission lines 67 are formed in these metallization levels.
- the object 81 analyzed by the imager of FIG. 5 is the skin of a person in which one wishes to localize cancerous cells. If for example, the cancerous cells comprise more water than the healthy cells, their dielectric constant is not the same as that of healthy cells and this inhomogeneity of the dielectric constant can be detected and located.
- the object to be analyzed is a liquid, for example blood, in which one wishes to know the concentration and/or the movement of suspended solid elements having a dielectric constant different from that of the liquid.
- FIG. 7 is a cross-sectional view in the plane BB of FIG. 5 and shows a shielded transmission line, for example a line 39 .
- the transmission line 39 and the shielding layer 71 are formed in metallization levels. The presence of the shielding layer 71 means that the functioning of the line is not dependent on the material of the superficial layer of the object to be analyzed.
- lines 39 and 43 are not shielded.
- the impedance of lines 39 , 43 of each pixel then depends on the object seen by this pixel and the frequency f of the oscillator varies as a consequence. It is possible to measure the frequencies f and or the varying output voltage or current of the pixels of the imager to reconstitute an image of the materials of the superficial layer of the object to be analyzed. In fact, it is possible to tailor the design of the transmission lines and the oscillators to be sensitive to specific dielectric constant ranges, or to be broadband.
- transmission lines different from those disclosed above can be used, for example coplanar transmission lines.
- each pixel can be replaced by any other oscillator, for example the oscillator disclosed in the article “A 283-to-296 GHz VCO with 0.76 mW Peak Output Power in 65 nm CMOS”, by Y. M. Tousi et al., published in Solid-state Circuits Conference Digest of Technical Papers (ISSCC), 2012 IEEE International, pages 258 to 260.
- ISSCC Solid-state Circuits Conference Digest of Technical Papers
- the pixels 63 of the imager are not read simultaneously.
- the pixels are read sequentially one by one. It is then possible to turn off the pixels that are not being read, for example by not biasing the oscillator of these pixels.
- the imager matrix 61 analyzes the superficial layer at a plurality of analysis depths.
- the lines of some groups of pixels 63 are coated with an insulating layer thicker than the lines of other groups of pixels.
- the oscillators of some groups of pixels operate at frequency different from those of other groups of pixels.
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
- Solid State Image Pick-Up Elements (AREA)
- Transforming Light Signals Into Electric Signals (AREA)
Abstract
Description
- 1. Technical Field
- The present disclosure relates to high frequency imagers, for example terahertz imagers, formed from a pixel matrix.
- 2. Description of the Related Art
- Terahertz imagers are devices adapted to capture the image of a scene based on terahertz waves, i.e., waves having a frequency that is for example comprised between 0.3 and 3 THz. A conventional imager such as disclosed in the U.S. Patent Application Publication No. 2014/070103 of the applicant includes a terahertz waves emitter for illuminating a scene to be imaged, and a sensor made of a pixel matrix that receives terahertz waves from the scene. Terahertz imagers are used in a large number of applications in which it is wished to see through some materials of a scene. Indeed, terahertz waves penetrate a large number of dielectric materials and non-polar liquids, are absorbed by water and are almost entirely reflected by metals. Terahertz imagers are in particular used in security scanners in airports to see through the clothes of a person or through luggage so as to detect metallic objects for example.
-
FIG. 1 is a reproduction of FIG. 1 of U.S. Patent Application Publication No. 2014/070103. Thesensor 1 includes a matrix 3 ofpixels 5 adapted to capture terahertz waves. A row decoder 7 receives a row selection signal 9 that indicates which row is to be read and provides to the lines of the matrix 3 acorresponding control signal 11. The pixel matrix 3 providesoutput signals 13 for each column of the matrix. Theoutput signals 13 are coupled to anoutput block 15 that selects and controls each column. The reading of the columns is controlled by acolumn decoder 17 coupled to theoutput block 15 and, in this example, the columns are read the one after the other. Theoutput block 15 provides anoutput signal 19 representing the value of thepixel 5 of the selected row and column. Theoutput signal 19 is amplified and coupled to an analog todigital converter 21. - To analyze the received signal, this signal is combined with a reference terahertz signal provided by an
oscillator 23. Theoscillator 23 is disposed outside of the matrix 3 and provides a same terahertz signal to a large number of pixels or to all the pixels of thesensor 1. Thisoscillator 23 is preferably coupled with a terahertz emitter, not shown, illuminating the scene to be analyzed. -
FIG. 2 is a reproduction of FIG. 3 of US application N°2014/070103 and illustrates an example of onepixel 5 of thesensor 1. Thepixel 5 comprises a detectingantenna 25 and adetection circuit 27 formed, in this example, of two N-MOS transistors 29, the gates of which are biased at a potential Vgate. The antenna is coupled to theoscillator 23 shown inFIG. 1 and to thedetection circuit 27. The output of thedetection circuit 27 is coupled to a row andcolumn selection circuit 31. Theselection circuit 31 is controlled by a signal RSEL provided by the row decoder 7 of thesensor 1 and by a signal CSEL provided by thecolumn decoder 17 of thesensor 1. Theanalog output signal 19 representing the value of thepixel 5 is available at a node COLOUT that is coupled to the converter 21 (FIG. 1 ) of thesensor 1. -
FIG. 3 is a reproduction of FIG. 5 of US application N°2014/070103 representing an example of afrequency oscillation circuit 33 of a terahertz imager. Thecircuit 33 comprises a ring oscillator made of an odd number N of inverters, three in this example. Each inverter includes aNMOS transistor 35 the drain of which is coupled to anode 37 and the source of which is coupled to ground. Eachnode 37 is coupled through aninductor 39 to the gate of thenext transistor 35, theinductors 39 having a same inductance value. Eachnode 37 is further coupled to asummation node 41 through aninductor 43, theinductors 43 all having the same inductance value. Thesummation node 41 is coupled to aDC voltage source 45 via aninductor 47 and to anoutput node 49 ofemitter 33 via aninductor 51. As shown, theoutput node 49 can be grounded, for example through aresistor 53. - In operation, the signal generated by the ring oscillator has a fundamental sinusoidal component of frequency F and harmonic sinusoidal components one of which has a frequency N*F. The value of each
inductor 43 is selected to implement a band-pass filter centered on the frequency N*F, and an output signal having a frequency fL0 equal to N*F is available at theoutput node 49 of theemitter 33 that is coupled to a terahertz emission antenna. -
FIG. 4 is a partial reproduction of FIG. 8 of US application N°2014/070103 and schematically illustrates an example implementation of thefrequency oscillation circuit 33 as disclosed in connection withFIG. 3 , but with five inverters instead of three. In this example, eachinductor - The terahertz imager disclosed in connection with
FIGS. 1-4 is a far-field imager provided for seeing through some materials of voluminous objects, seen at a far distance from the object, having sizes greater than 10 cm, preferably greater than 1 meter. The resolution of an image obtained with a far-field imager is at best of about the operating wavelength of the imager, i.e., 1 mm at a frequency of 300 GHz and 0.1 nm at a frequency of 3 THz. To improve the spatial resolution of a far-field imager it is possible to increase the operating frequency of the imager. However, this raises various problems. Thus, a far-field terahertz imager is not adapted to obtaining an image having a resolution in the order of tenths of a micrometer. - Near-field terahertz imagers provide an image of an object to be analyzed with a resolution in the order of tenths of a micrometer. However, these imagers are complex to implement, in particular due to the fact that they use terahertz emission sources such as coherent synchrotron radiations, and optical systems such as elliptical mirrors. An example of such a near-field imager is disclosed in the article “THz near-field imaging of biological tissues employing synchrotron radiation” of Shade et al., published in 2005 in Ultrafast Phenomena in Semiconductors and Nanostructure Materials IX, 46.
- Thus, it would be desirable to provide a near-field terahertz imager that is as simple as possible and that provides an image having a resolution in the order of tenths of a micrometer.
- Thus, an embodiment provides a high frequency imager comprising a pixel matrix, each pixel comprising: a high frequency oscillator; a transmission line positioned at a distance from an active surface of the imager smaller than the operating wavelength of the oscillator, a first end of the line being coupled to the oscillator; and a read circuit coupled to a second end of the line.
- According to an embodiment, the read circuit of each pixel provides a signal representative of the impedance of the transmission line.
- According to an embodiment, the oscillator of each pixel comprises second transmission lines.
- According to an embodiment, a layer adapted to block the propagation of the high frequency waves covers at least the second lines.
- According to an embodiment, the read circuit of a pixel provides a signal representative of the frequency of the oscillator of the pixel.
- According to an embodiment, the transmission lines are of the microstrip type.
- According to an embodiment, the imager is adapted to operate at a frequency selected in a range of 0.3 to 3 THz.
- The foregoing and other features, aspects and advantages of the present disclosure will become apparent from the following detailed description of embodiments, given by way of illustration and not limitation with reference to the accompanying drawings in which:
-
FIG. 1 , described above, is a reproduction of FIG. 1 of US patent application N°2014/070103 schematically representing an example of a terahertz imager sensor; -
FIG. 2 , described above, is a reproduction of FIG. 3 of US patent application N°2014/070103 schematically representing an example of a pixel of the sensor ofFIG. 1 ; -
FIG. 3 , described above, is a reproduction of FIG. 5 of US patent application N°2014/070103 schematically illustrating an example of terahertz frequency oscillation circuit; -
FIG. 4 , described above, is a reproduction of FIG. 8 of US patent application N°2014/070103 schematically representing an example of implementation of the circuit ofFIG. 3 ; -
FIG. 5 is a schematic plan view representing a portion of the pixels of a terahertz imager according to an embodiment of the present disclosure; -
FIG. 6 is a cross-sectional view in a plane AA ofFIG. 5 and represents a transmission line of the imager; and -
FIG. 7 is a cross-sectional view in a plane BB ofFIG. 5 and represents a shielded transmission line of the imager. - The same elements have been designated by same references in the various figures and additionally the figures are not drawn to scale. In the following description, the terms “over” and “higher” refer to the orientations of the related elements in the corresponding figures. Unless stated otherwise, the expressions “about” and “in the order of” mean within 10%, or preferentially within 5%, of the stated value.
-
FIG. 5 is a schematic top view of an embodiment of a terahertz imager, only a portion of the imager being shown in this figure. The imager comprises amatrix 61 ofpixels 63, three pixels of a column of thematrix 61 being shown inFIG. 5 . Each pixel comprises an oscillator, for example such as disclosed in connection withFIGS. 3 and 4 , aread circuit 65 and atransmission line 67. An end of thetransmission line 67 is coupled to thenode 41 ofoscillator 33 and the other end is coupled to theread circuit 65. The read circuit of each pixel is adapted to provide a signal representative of the impedance value ofline 67. The read circuit of each pixel is coupled to a line and column selection circuit (not shown) controlled by a line decoder and a column decoder (not shown). In this embodiment, theoscillator 33 and in some embodiments thedetection circuit 65 of eachpixel 63 are shielded by ashielding layer 71, for example a metal layer, blocking the propagation of high frequency waves. - In operation, the
oscillator 33 of each pixel is biased by a DC voltage source coupled to thetransmission line 67, for example through thedetection circuit 65 of the pixel. Theoscillator 33 thus provides a terahertz signal having a frequency f and a wavelength λ to thetransmission line 67. -
FIGS. 6 and 7 are respectively a cross-sectional view in a plane AA ofFIG. 5 and a cross-sectional view in a plane BB ofFIG. 5 . -
FIG. 6 shows threetransmission lines 67 of threepixels 63 of the imager ofFIG. 5 . Thetransmission lines 67 are formed in metallization levels buried in an insulatinglayer 73 laying on asemiconductor support 75. Each transmission line comprises amicrostrip 77 above aconductive band 79 forming a ground plane. Themicrostrip 77 of eachtransmission line 67 is covered by an insulating layer having a thickness smaller than A and preferably smaller than 0.1λ, where λ is the wavelength of the signal of the oscillator coupled to the line. - An
object 81 to be analyzed is arranged against the upper face or active face of the pixel matrix of the imager. The object may include a plurality of materials having different dielectric constants and present inhomogeneities of effective dielectric constant. - When a terahertz signal of frequency f and wavelength λ is applied to a
line 67, terahertz fields radiate from themicrostrip 77 to theground plane 79, as shown by dotted lines for the right-hand pixel ofFIG. 6 , and a part of the fields leaks outside of the imager elements. These terahertz fields penetrate a superficial layer of theobject 81 to be analyzed. The term “analysis depth” designates the thickness of the superficial layer of the object in which these terahertz waves penetrate. The analysis depth is in the order of several wave lengths λ, for example in the range to 3λ, i.e., 0.1 to 0.3 mm if the frequency f is equal to 3 THz, and from 1 to 3 mm if the frequency f is equal to 300 GHz. - The impedance of a
transmission line 67 depends upon the effective dielectric constant of the imager elements and of the material ofobject 81 that is positioned over this line and thus will be different for the two pixels arranged on the right inFIG. 6 , which are positioned under aninhomogeneity 83, and for the pixel arranged on the left ofFIG. 6 . An image of the dielectric constants of the material of the upper layer of theobject 81 is thus obtained from the set of output signals of the pixels of the imager. The resolution of the imager thus corresponds to the dimensions of its pixels. For example, in the case of anoscillator 33 with five inverters providing a signal at 600 GHz, each pixel can have lateral dimensions of 20 to 50 μm. - A characteristic of the above disclosed pixels is that the
transmission line 67 of each pixel serves as an emitter of terahertz waves for illuminating a portion of an object to be analyzed and is also used as a detector to capture a signal associated with the effective dielectric constant of this portion. - As an example, the
semiconductor support 75 is a bulk silicon substrate or a SOI type (“Silicon On Insulator”) substrate in which are formed the electronic components of the imager, in particular the transistors of the pixels. This support is covered with metallization levels of an interconnection structure of the electronic components formed in the semiconductive support. Themicrostrip 77 and the ground planes 79 of thetransmission lines 67 are formed in these metallization levels. - In an example application, the
object 81 analyzed by the imager ofFIG. 5 is the skin of a person in which one wishes to localize cancerous cells. If for example, the cancerous cells comprise more water than the healthy cells, their dielectric constant is not the same as that of healthy cells and this inhomogeneity of the dielectric constant can be detected and located. - In another example, the object to be analyzed is a liquid, for example blood, in which one wishes to know the concentration and/or the movement of suspended solid elements having a dielectric constant different from that of the liquid.
-
FIG. 7 is a cross-sectional view in the plane BB ofFIG. 5 and shows a shielded transmission line, for example aline 39. Thetransmission line 39 and theshielding layer 71 are formed in metallization levels. The presence of theshielding layer 71 means that the functioning of the line is not dependent on the material of the superficial layer of the object to be analyzed. - In a variant,
lines lines - Specific embodiments have been disclosed. Variants and modifications will appear to those skilled in the art. In particular, transmission lines different from those disclosed above can be used, for example coplanar transmission lines.
- The oscillator contained in each pixel can be replaced by any other oscillator, for example the oscillator disclosed in the article “A 283-to-296 GHz VCO with 0.76 mW Peak Output Power in 65 nm CMOS”, by Y. M. Tousi et al., published in Solid-state Circuits Conference Digest of Technical Papers (ISSCC), 2012 IEEE International, pages 258 to 260.
- In practice, the
pixels 63 of the imager are not read simultaneously. For example, the pixels are read sequentially one by one. It is then possible to turn off the pixels that are not being read, for example by not biasing the oscillator of these pixels. - In some embodiments, the
imager matrix 61 analyzes the superficial layer at a plurality of analysis depths. For example, the lines of some groups ofpixels 63 are coated with an insulating layer thicker than the lines of other groups of pixels. Additionally or alternatively, the oscillators of some groups of pixels operate at frequency different from those of other groups of pixels. - While terahertz imagers have been disclosed above, it will be noted that the description applies to any near-field high frequency imager, where high frequency means a frequency of 10 GHz or more.
- Various embodiments and variants have been disclosed. It will be apparent to those skilled in the art that the various elements in the various embodiments can be combined in any combination without inventive step.
- The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments.
- These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.
Claims (18)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1553569 | 2015-04-21 | ||
FR1553569A FR3035499A1 (en) | 2015-04-21 | 2015-04-21 | IMAGEUR TERAHERTZ IN NEAR FIELD |
Publications (2)
Publication Number | Publication Date |
---|---|
US9464933B1 US9464933B1 (en) | 2016-10-11 |
US20160313177A1 true US20160313177A1 (en) | 2016-10-27 |
Family
ID=54366255
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US14/920,373 Active US9464933B1 (en) | 2015-04-21 | 2015-10-22 | Near-field terahertz imager |
Country Status (4)
Country | Link |
---|---|
US (1) | US9464933B1 (en) |
EP (1) | EP3086101B1 (en) |
CN (2) | CN106067950B (en) |
FR (1) | FR3035499A1 (en) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR3035499A1 (en) * | 2015-04-21 | 2016-10-28 | St Microelectronics Sa | IMAGEUR TERAHERTZ IN NEAR FIELD |
FR3079665A1 (en) * | 2018-03-28 | 2019-10-04 | Hani Sherry | IMAGEUR TERAHERTZ WITH CLOSE FIELD |
CN112557762B (en) * | 2019-09-25 | 2022-09-02 | 天津大学 | High-precision terahertz near field imaging array unit |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN101526464B (en) * | 2008-03-05 | 2011-05-11 | 清华大学 | Phase contrast imaging method and device |
EP2408361A1 (en) * | 2009-03-20 | 2012-01-25 | Solianis Holding AG | Device for electrically measuring at least one parameter of a mammal's tissue |
JP5606061B2 (en) * | 2009-12-25 | 2014-10-15 | キヤノン株式会社 | Oscillating element |
FR2995449A1 (en) * | 2012-09-12 | 2014-03-14 | St Microelectronics Sa | IMAGEUR TERAHERTZ |
FR2995475A1 (en) * | 2012-09-12 | 2014-03-14 | St Microelectronics Sa | HIGH FREQUENCY OSCILLATOR |
US8895913B2 (en) * | 2012-12-17 | 2014-11-25 | Wave Works, Inc. | Traveling wave based THz signal generation system and method thereof |
FR3035499A1 (en) * | 2015-04-21 | 2016-10-28 | St Microelectronics Sa | IMAGEUR TERAHERTZ IN NEAR FIELD |
-
2015
- 2015-04-21 FR FR1553569A patent/FR3035499A1/en active Pending
- 2015-10-22 US US14/920,373 patent/US9464933B1/en active Active
- 2015-10-22 EP EP15191131.0A patent/EP3086101B1/en active Active
- 2015-11-20 CN CN201510813139.2A patent/CN106067950B/en active Active
- 2015-11-20 CN CN201520935000.0U patent/CN205249361U/en active Active
Also Published As
Publication number | Publication date |
---|---|
CN106067950A (en) | 2016-11-02 |
CN205249361U (en) | 2016-05-18 |
EP3086101A1 (en) | 2016-10-26 |
EP3086101B1 (en) | 2022-05-18 |
CN106067950B (en) | 2019-04-26 |
US9464933B1 (en) | 2016-10-11 |
FR3035499A1 (en) | 2016-10-28 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
Lisauskas et al. | Exploration of terahertz imaging with silicon MOSFETs | |
US8058618B2 (en) | High sensitivity THz signal detector and camera | |
EP2047294B1 (en) | A detector for and a method of detecting electromagnetic radiation | |
Zdanevičius et al. | Camera for high-speed THz imaging | |
CN108007566B (en) | Terahertz detector | |
US9464933B1 (en) | Near-field terahertz imager | |
Lisauskas et al. | Terahertz imaging with Si MOSFET focal-plane arrays | |
US20120038507A1 (en) | Portable radiometric imaging device and a corresponding imaging method | |
CN111971548B (en) | Terahertz reflection imaging system | |
US20130161514A1 (en) | High-speed giga-terahertz imaging device and method | |
US9726548B2 (en) | Terahertz imager | |
Lisauskas et al. | Detectors for terahertz multi-pixel coherent imaging and demonstration of real-time imaging with a 12x12-pixel CMOS array | |
JP7333083B2 (en) | Near-field terahertz imaging device | |
Palma et al. | A model of high-frequency self-mixing in double-barrier rectifier | |
Lisauskas et al. | Terahertz detection and coherent imaging from 0.2 to 4.3 THz with silicon CMOS field-effect transistors | |
Boppel et al. | Towards monolithically integrated CMOS cameras for active imaging with 600 GHz radiation | |
CN110657887B (en) | Terahertz detector based on cross-coupling structure | |
Liu et al. | CMOS Integrated FET-based Detectors for Radiation from 0.7-3.6 THz | |
Liu et al. | Exploration of high-speed 3.0 THz imaging with a 65 nm CMOS process | |
Villani et al. | OVERMOS—CMOS Hi-Res MAPS detectors for HEP applications | |
Trichopoulos et al. | Imaging performance of a THz focal plane array | |
Coppa et al. | Active electric near field imaging of electronic devices | |
Ortolani et al. | Imaging the coupling of terahertz radiation to a high electron mobility transistor in the near-field | |
Schuster et al. | THz imaging with low-cost 130 nm CMOS transistors | |
Lisauskas et al. | Terahertz sensing and imaging with silicon field-effect transistors up to 9 THz |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: STMICROELECTRONICS SA, FRANCE Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SHERRY, HANI;REEL/FRAME:038603/0395 Effective date: 20151022 |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 4 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 8TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1552); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Year of fee payment: 8 |
|
AS | Assignment |
Owner name: STMICROELECTRONICS FRANCE, FRANCE Free format text: CHANGE OF NAME;ASSIGNOR:STMICROELECTRONICS SA;REEL/FRAME:067055/0481 Effective date: 20230126 |