WO1998024113A1 - Infrared camera - Google Patents
Infrared camera Download PDFInfo
- Publication number
- WO1998024113A1 WO1998024113A1 PCT/NL1997/000623 NL9700623W WO9824113A1 WO 1998024113 A1 WO1998024113 A1 WO 1998024113A1 NL 9700623 W NL9700623 W NL 9700623W WO 9824113 A1 WO9824113 A1 WO 9824113A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- particles
- state
- electrically charged
- charged particles
- electron
- Prior art date
Links
- 239000002245 particle Substances 0.000 claims abstract description 49
- 238000006243 chemical reaction Methods 0.000 claims abstract description 13
- 230000005284 excitation Effects 0.000 claims abstract description 6
- 238000001514 detection method Methods 0.000 claims abstract description 4
- 230000005855 radiation Effects 0.000 claims description 11
- 230000005684 electric field Effects 0.000 claims description 9
- 229910052779 Neodymium Inorganic materials 0.000 claims description 2
- 239000004411 aluminium Substances 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- 229910052792 caesium Inorganic materials 0.000 claims description 2
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 claims description 2
- 230000008020 evaporation Effects 0.000 claims description 2
- 238000001704 evaporation Methods 0.000 claims description 2
- 239000002223 garnet Substances 0.000 claims description 2
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 claims description 2
- 229910052701 rubidium Inorganic materials 0.000 claims description 2
- IGLNJRXAVVLDKE-UHFFFAOYSA-N rubidium atom Chemical compound [Rb] IGLNJRXAVVLDKE-UHFFFAOYSA-N 0.000 claims description 2
- 150000001340 alkali metals Chemical group 0.000 claims 2
- 150000002500 ions Chemical class 0.000 description 9
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- 230000003595 spectral effect Effects 0.000 description 4
- 230000003287 optical effect Effects 0.000 description 3
- 230000007704 transition Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000005281 excited state Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000001443 photoexcitation Effects 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 239000003513 alkali Substances 0.000 description 1
- 230000003321 amplification Effects 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J31/00—Cathode ray tubes; Electron beam tubes
- H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
- H01J31/49—Pick-up adapted for an input of electromagnetic radiation other than visible light and having an electric output, e.g. for an input of X-rays, for an input of infrared radiation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J31/00—Cathode ray tubes; Electron beam tubes
- H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
- H01J31/50—Image-conversion or image-amplification tubes, i.e. having optical, X-ray, or analogous input, and optical output
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J47/00—Tubes for determining the presence, intensity, density or energy of radiation or particles
Definitions
- the invention relates to an apparatus for depicting an object which emits or reflects radiation in the infrared range, for instance an infrared camera, comprising an objective for projecting the object on a focal plane upon which conversion means have been provided for converting photons in the infrared range emitted or reflected by the object into electrically charged particles as a funtion of position of the emission or respectively the reflection of the photons, and position detection means for detecting the position of the emission of the electrically charged particles .
- infrared cameras by means of which an infrared emitting or reflecting object is projected upon a projection plane which is provided with a layer of infrared sensitive material in the condensed phase, by which material photons in the infrared range are converted in an electron stream which can be detected as a function of position in order to construct an image of the original object in the visible part of the spectrum.
- the known infrared cameras have the drawback that their spectral range in the infrared region is limited, that their sensitivity is low, which means that the number of photons in order to generate a detectable signal is necessarily relatively high, that the freedom for the shutter time to be set, i.e. the time-resolution, is limited, and that the selectivity for the wavelength in the infrared range is little.
- Another object is to provide an infrared camera having a high selectivity for the wavelength of the infrared radiation emitted or reflected by the object to be depicted.
- the conversion means comprise a gaseous medium for absorbing the photon pulse to be detected and for emitting the electrically charged particles.
- the electrically charged particles are for instance electrons or ions.
- the pulse conversion means comprise a gaseous medium
- the spectral range of a photon pulse for detecting is not limited to the infrared region, but the spectral range can be extended as required to the wavelength region of the far-infrared light.
- the apparatus is provided with excitation means for bringing particles into an excited electron state and the gaseous medium contains particles for bringing into this excited electron state in order in this state to absorb the photon pulse and to emit the electrically charged particles .
- the excited electron state is for instance a Rydberg state .
- pulse conversion means are obtained for converting radiation in the infrared or far infrared region and therefore low-energy photons into a stream electrically charged particles.
- the relatively low energy of a far-infrared photon is sufficiently high to cause photo-ionization of an atom in a Rydberg state and to liberate a weakly bonded electron from that atom.
- the active cross-section for photo-ionization is high for a gas with Rydberg atoms, so that relatively few photons are required for this process.
- a gaseous medium comprising particles for bringing into an excited state is for instance admitted into the apparatus via a gas supply line .
- the apparatus according to the invention comprises an evaporation oven for bringing into a gaseous state the particles for bringing into an excited electron state .
- Atoms for bringing into an excited electron state which are suitable for use in an apparatus according to the invention are for instance alkali atoms, in particular the elements Rb (rubidium) or Cs (caesium) .
- the atoms are brought into an excited electron state for instance by excitation using a laser light source.
- a laser light source for use in an apparatus according to the invention is for instance a dye laser pumped with an Nd:YAG(neodymium:yttrium-aluminium garnet) laser.
- the second harmonic of the light of an NdrYAG laser is particularly suitable for pumping the dye laser in such an apparatus .
- the apparatus comprises a diode laser.
- the light of the laser light source is projected into the focal plane of the object to be depicted according to a method known per se by means of for instance a cylindrical lens, in such a way that at the site of said focal plane in the gaseaous medium a plane comes into being in which particles are to be brought into an excited electron state, and particles outside said plane are not to be brought into said excited electron state.
- the apparatus comrises field generating means for generating an electric field in order to cause ionisation of a particle having an excited electron brought in a Rydberg state.
- Photo-excitation is said to be there when the bonding energy of an electron in a Rydberg state is greater than the enery of in incoming photon in the infrared region, so no photo-ionization can occur, but the electron is driven by the infrared photon to a Rydberg state which has a higher energy level.
- the conversion means in this preferred embodiment are only sensitive to infrared radiation having wavelenghts which give rise to photo-ionization of the Rydberg particle.
- the excited state should have an energy sufficiently high in order to give rise in the static electric field to be generated to the formation of a positive ion and an electron.
- the electric field in this preferred embodiment can be chosen in such a way that the conversion means are only sensitive to particular wavelengths in the infrared region, and therefore only sensitive to objects which emit or reflect light having said particular wavelength.
- Photo-de-excitation is said to be there when an incident photon in the infrared region drives an electron which is in an initial Rydberg state, whereby field ionization can occur, to another, de-excited Rydberg state with a lower enery level, having a greater bonding energy.
- the electric field in this preferred embodiment can be chosen in such a way that the conversion means are only sensitive to wavelengths in the infrared region which bring the particles in the conversion means into a de-excited Rydberg state, whereas particles in the de-excited state which have not absorbed a photon by field ionization do give rise to the formation of a positive ion and an electron.
- the electric field in this preferred embodiment can be chosen such that the conversion means are just insensitive to certain wavelengths in the infrared region, and therefore give rise to creation of a negative xmage .
- the apparatus comprises field generating means for generating a magnetic field in order to tune the energy level of an electron in the Rydberg state. Because the energy level of an electron in a Rydberg state is tunable by means of a magnetic field (just as it is by means of an electric field) , the transition of an electron to this state can be made selective for a photon to be absorbed in the infrared region, in such a way that only photons having an energy which corresponds to said transition are absorbed and the apparatus is insenstive to photons having a different energy.
- a camera for the infrared region objects emitting or reflecting infrared radiation with a wavelength up to for instance about 100 micrometers can be observed with a high resolution, for instance 10 micrometers, with a very fast shutter times, for instance 1 nanosecond.
- FIG. 1 shows a schematic view of an embodiment of an infrared camera according to the invention. Shown are an infrared camera 1 for making by means of an optical element 7 a picture of an object 6 which emits or reflects infrared radiation, with gastight casing 2, which comprises voltage grids 3, 4 (connection and supply of which are not shown) , channel plates 8, 9 with high-voltage feed- throughs 16, 17 respectively, phosphor screen 9, oven 10 and window 11.
- the infrared camera 1 further comprises a CCD camera 14 coupled to a computer 13 and a diode laser 15.
- the object 6 emitting or reflecting infrared light is projected by means of the optical element 7 upon the plane 21.
- De infrared radiation passes a grid 3 and is absorbed by gas present in the casing 2, which gas is excited by laser light (represented by arrow 22) from diode laser 15 via window 11 and is in a Rydberg state. Because of photo-emission a gas particle disintegrates into an electron and a positively charged ion.
- a single incident electrically charged particle on the channel plates 8 , 9 results in 10 7 electrons which strike the phosphor screen 19, where the electrons are converted into photons at an amplification factor of 10.
- the multiplication factor 10 7 will only be attained if the voltage difference over the sides of the channel plates 8, 9 which are directed away from each other is sufficiently high (typically 2 kV) .
- This voltage difference is applied by means of the electrical feed-througs 16, 17.
- an image 20 of the object 6 is made on the phosphor screen 19.
- This image 20 is read using CCD camera 14 and processed using computer 13.
- optics can be placed between the focal plane 21 and the first channel plate 8, in order to make the image of the charged particles on the first channel plate 8 as sharp as possible.
- Infrared camera 1 is not sensitive to infrared radiation before diode laser 15 has excited the gas particles to a Rydberg state. This excitation process is comparable with the opening of a shutter in a prior art camera . As soon as the voltage difference between the feed-throughs 16, 17 has dropped below a certain critical value (for instance 1500 V) , incident ions or electrons will no longer be detected. The camera is in that case not sensitive to Rydberg particles which are ionized after the voltage difference between the feed-throughs 16, 17 has been dropped, taking into account the transit time of the electrons or ions from the photosensitive focal plane 21 and the front channel plate 8. This process is comparable to the closing of a shutter in a prior art camera .
- a certain critical value for instance 1500 V
- a diode laser can be turned on within a time period of 10 "9 sec, and the voltage across the channel plates 8, 9 can drop within a similar time period, shutter times shorter than 1 nanosecond can be realized, so that the so called dark current of the infrared camera according to the invention is very little.
- the infrared camera 1 is only sensitive to infrared radiation the wavelength of which matches with the transition from the initial Rydberg state to the other Rydberg state, and besides time- and position-resolving performances there is also a matter of wavelength- selectivity.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP52456098A JP2001509301A (en) | 1996-11-27 | 1997-11-14 | Infrared camera |
AU49706/97A AU4970697A (en) | 1996-11-27 | 1997-11-14 | Infrared camera |
EP97912576A EP0988644A1 (en) | 1996-11-27 | 1997-11-14 | Infrared camera |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL1004620 | 1996-11-27 | ||
NL1004620A NL1004620C2 (en) | 1996-11-27 | 1996-11-27 | Infrared camera. |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998024113A1 true WO1998024113A1 (en) | 1998-06-04 |
Family
ID=19763935
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/NL1997/000623 WO1998024113A1 (en) | 1996-11-27 | 1997-11-14 | Infrared camera |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0988644A1 (en) |
JP (1) | JP2001509301A (en) |
AU (1) | AU4970697A (en) |
NL (1) | NL1004620C2 (en) |
WO (1) | WO1998024113A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL1011916C2 (en) * | 1999-04-28 | 2000-10-31 | Stichting Fund Ond Material | Infrared color camera. |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4714607B2 (en) * | 2006-03-14 | 2011-06-29 | 新日本製鐵株式会社 | Blast furnace outflow measurement system, blast furnace outflow measurement method, and computer program |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4914296A (en) * | 1988-04-21 | 1990-04-03 | The Boeing Company | Infrared converter |
WO1996033508A1 (en) * | 1995-04-21 | 1996-10-24 | Stichting Voor Fundamenteel Onderzoek Der Materie | Apparatus for detecting a photon pulse |
-
1996
- 1996-11-27 NL NL1004620A patent/NL1004620C2/en not_active IP Right Cessation
-
1997
- 1997-11-14 AU AU49706/97A patent/AU4970697A/en not_active Abandoned
- 1997-11-14 WO PCT/NL1997/000623 patent/WO1998024113A1/en not_active Application Discontinuation
- 1997-11-14 EP EP97912576A patent/EP0988644A1/en not_active Withdrawn
- 1997-11-14 JP JP52456098A patent/JP2001509301A/en active Pending
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4914296A (en) * | 1988-04-21 | 1990-04-03 | The Boeing Company | Infrared converter |
WO1996033508A1 (en) * | 1995-04-21 | 1996-10-24 | Stichting Voor Fundamenteel Onderzoek Der Materie | Apparatus for detecting a photon pulse |
Non-Patent Citations (1)
Title |
---|
CORKUM P B ET AL: "Measuring subfemtosecond pulses", IQEC '94. SUMMARIES OF PAPERS PRESENTED AT THE INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE. VOL.9. 1994 TECHNICAL DIGEST SERIES CONFERENCE EDITION (CAT. NO.94CH3462-9), IQEC'94. INTERNATIONAL QUANTUM ELECTRONICS CONFERENCE, ANAHEIM, CA, USA, 8-13 MA, ISBN 0-7803-1973-7, 1994, WASHINGTON, DC, USA, OPT. SOC. AMERICA, USA, pages 159, XP002036371 * |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL1011916C2 (en) * | 1999-04-28 | 2000-10-31 | Stichting Fund Ond Material | Infrared color camera. |
WO2000067292A1 (en) * | 1999-04-28 | 2000-11-09 | Stichting Voor Fundamenteel Onderzoek Der Materie | Infrared colour camera |
Also Published As
Publication number | Publication date |
---|---|
NL1004620C2 (en) | 1998-05-28 |
EP0988644A1 (en) | 2000-03-29 |
AU4970697A (en) | 1998-06-22 |
JP2001509301A (en) | 2001-07-10 |
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