WO1998002735A1 - Signal processing unit of a device for photothermally testing a surface of a test piece - Google Patents
Signal processing unit of a device for photothermally testing a surface of a test piece Download PDFInfo
- Publication number
- WO1998002735A1 WO1998002735A1 PCT/DE1997/001439 DE9701439W WO9802735A1 WO 1998002735 A1 WO1998002735 A1 WO 1998002735A1 DE 9701439 W DE9701439 W DE 9701439W WO 9802735 A1 WO9802735 A1 WO 9802735A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- detector
- processing unit
- signal processing
- speed
- test specimen
- Prior art date
Links
- 238000012360 testing method Methods 0.000 title claims abstract description 81
- 238000012545 processing Methods 0.000 title claims abstract description 16
- 230000005855 radiation Effects 0.000 claims abstract description 33
- 230000005284 excitation Effects 0.000 claims abstract description 18
- 230000003068 static effect Effects 0.000 claims abstract 2
- 238000005259 measurement Methods 0.000 claims description 17
- 238000012937 correction Methods 0.000 claims description 16
- 238000011156 evaluation Methods 0.000 claims description 11
- 230000003287 optical effect Effects 0.000 abstract description 7
- 230000000052 comparative effect Effects 0.000 abstract 1
- 230000001186 cumulative effect Effects 0.000 abstract 1
- 238000000034 method Methods 0.000 description 8
- 238000001816 cooling Methods 0.000 description 3
- 239000004922 lacquer Substances 0.000 description 3
- 230000010355 oscillation Effects 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 230000036962 time dependent Effects 0.000 description 3
- 230000004888 barrier function Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000002123 temporal effect Effects 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000006378 damage Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 238000007591 painting process Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000009897 systematic effect Effects 0.000 description 1
- 230000005919 time-dependent effect Effects 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N25/00—Investigating or analyzing materials by the use of thermal means
- G01N25/72—Investigating presence of flaws
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/171—Systems in which incident light is modified in accordance with the properties of the material investigated with calorimetric detection, e.g. with thermal lens detection
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/36—Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/64—Devices characterised by the determination of the time taken to traverse a fixed distance
- G01P3/68—Devices characterised by the determination of the time taken to traverse a fixed distance using optical means, i.e. using infrared, visible, or ultraviolet light
Definitions
- the invention relates to a signal processing unit of a device for photothermal testing of a surface of a test specimen with a detector which can be subjected to heat radiation originating from a test area and induced by excitation radiation incident on the test specimen, and to an evaluation device connected downstream of the detector, with which the time-dependent evaluation device can be used Output signal of the detector specimen properties can be determined.
- Such a signal processing unit is known from DE 38 20 862 AI, which is part of a device for photothermal testing of a surface of a test specimen.
- the photothermal testing of a surface the temporal course of the induced thermal radiation originating from a test area after pulsed exposure to excitation radiation is registered and evaluated.
- the recorded temperature-time diagram can be used, for example, to identify defects in the test specimen or, after determining the phase shift between a rectangular pulse of the excitation radiation and the onset and decay of the thermal radiation, the layer thickness of a lacquer or powder layer applied to the test specimen.
- test specimens With this method, important properties of test specimens can be determined without contact or destruction.
- this requires that the Do not move the test area and the detector intended to detect the induced thermal radiation relative to one another, since otherwise time-dependent changes in intensity occur which are not based on warm-up and cool-down processes determined by test specimen characteristics. Therefore, particularly when using this technique for quality control in continuously running painting or coating processes, the test specimen was either stopped for a short time for measurement or the detector was moved from a start to an end position during a measurement cycle in such a way that no relative speed between the detector and the transported test specimen occurs.
- DE 43 43 076 A1 proposes to provide the area exposed to the excitation radiation significantly larger than the test area detected by the detector, so that movement of the test specimen within the measuring time can be tolerated by measurement technology is than the test area detected by the detector lies within the area of the surface exposed to the excitation radiation.
- the area exposed to the excitation radiation is irradiated with an essentially homogeneous intensity in order to avoid temporal intensity variations due to warming up and cooling down processes.
- Another disadvantage of the latter procedure is that only a small zone of the area exposed to the excitation radiation is actually used for testing, so that a large part of the energy of the excitation radiation has been used uselessly.
- the invention has for its object to provide a signal processing unit of the type mentioned, with which it is possible to measure reliably even in the case of relative speeds between the detector and the test area in an energy-saving and inexpensive manner.
- the evaluation device has a speed measuring device with which the relative speed between the detector and the test area can be determined, and that by means of a correction element of the evaluation device with an output signal of the speed measuring device, the output signal of the Detector can be corrected by correcting the intensity of the detected thermal radiation to a stationary test area.
- the speed information thus obtained can then be corrected with the correction element for checking the intensity measurement for a measurement in relative rest, so that the measurement result is free from simulated time-dependent effects.
- the area of the surface exposed to the excitation radiation can essentially correspond to the size of the test area, so that relatively little excitation energy is required.
- the detector can be installed in a fixed position, so that the outlay on equipment is considerably reduced.
- a light barrier is suitable as the speed measuring device, in which the movement of an edge of the test specimen can be detected with several detectors. Knowing the location of the speed measurement, the geometry of the test specimen and the position of the test area, the speed in the test area can then be calculated and output and its influence on the output signal of the detector can be eliminated.
- the speed is already due to the different intensity ratios of the registered heat rays. development between individual segments can be determined directly in the test area without the need for additional measuring devices. In addition to considerably less equipment, this has the great advantage that the relative speed can be determined directly and independently of the test specimen geometry.
- the figure shows a signal processing unit with a two-segment detector for the direct detection of the relative speed of the test specimen in the test area.
- the figure shows a schematic representation of an optical part 1 known per se of a device for photothermal testing of a surface of a test specimen.
- the optical part 1 has a light source 2, for example a laser in the infrared spectral range, the output light of which falls as an excitation radiation 3 in rectangular pulses via an excitation lens 4 and deflected onto a test specimen 6 by a dichroic mirror 5.
- the excitation radiation 3 acting on the test specimen 6 induces heat radiation 8 in a test area 7, the part of which extends collinearly in a superimposition section 9 after passing through the dichroic mirror 5 and an imaging optical system 10 acts on a segment detector 11 of a signal processing unit 12.
- the test area 7 detectable by the detector 11 corresponds to essentially the area acted upon by the excitation radiation 3 or is slightly larger.
- the figure shows a case that is frequently encountered in the production of coated test specimens 6, in which the test specimen 6 is slidably attached to a running rail 15 via suspensions 13, 14.
- the test specimen 6 is displaced transversely to the overlay section 9, for example in a direction represented by an arrow 16.
- an oscillation of the test specimen 6 indicated by an arrow 17 can occur in particular even if the relative speed changes abruptly.
- these processes also influence the time course of the intensity of the thermal radiation 8 impinging on the segment detector 11.
- the segment detector 11 is equipped with a first segment 18 and a second segment 19 which are flush with one another in the form of semicircularly framed disks with their circular diameters.
- the circle diameters of the segments 18, 19 are oriented transversely to the direction of displacement and oscillation.
- Each segment 18, 19 is connected via an amplifier 20, 21 to an analog / digital converter 22, 23.
- the intensities of the heat radiation 8 detected by the segments 18, 19 of the segment detector 11 are controlled by a clock generator 24 and can be converted into digital output signals.
- the output signals of the analog / digital converter 22, 23 can be fed to a summing element 25, with which the sum of the output signals can be formed as a value for the total intensity of the heat radiation 8 falling on the segment detector 11. Furthermore, the output signals of the analog / digital converters 22, 23 can be fed to a division element 26, with which a relative value can be determined from the ratio of the output signal of one segment 18, 19 to the output signal of the other segment 19, 18. The output signal of the division element 26 assigned to this relative value can be fed to a drift correction element 27. The output signal of the clock generator 24 can also be fed to the summing element 25 and the drift correction element 27 as measuring clock signals.
- each intensity ratio is a relative speed of the test specimen 6 with respect to the segment detector 11 fixedly arranged to the optical part 1 assignable.
- the relative position of the detector 11 in relation to the test area 7 is important.
- each segment 18, 19 is exposed to the same intensity of heat radiation 8. If, on the other hand, the test specimen 6 moves at a constant speed in the direction of the arrow 16, the greater part of the intensity of that detected by the segment detector 11 shifts in the cooling phase Heat radiation 8 on the segment 19 arranged in the direction of arrow 16.
- the detector 11 Even during the heating phase, when the detector 11 is centered in position, there is an uneven distribution of the intensity of the heat radiation 8 over the segments 18, 19 via the segment detector 11 if the test specimen 6 moves relative to the detector 11. In this case, the different intensity distribution is due to the fact that the different zones of the test area 7 have been exposed to the excitation radiation 3 for different lengths of time at the moment of the measurement.
- the output signal of the drift correction element 27 corresponds to a correction factor which is dependent on the relative speed and is read from the calibration value table and is fed into an intensity correction element 28.
- the output signal of the summing element 25, which is likewise fed to the intensity correction element 28, from the added individual intensities of the segments 18, 19 of the segment detector 11 for a stationary test region 7 Can be corrected by compensating for the decrease in the total intensity detected by the segment detector 11 caused by the relative speed, which would simulate, for example, a smaller layer thickness of a lacquer or powder layer.
- the speeds determined with the drift correction element 27 are expediently fed in for control purposes in a storage and output part (not shown).
- the output signal of the intensity correction element 28 can be read by the clock generator 24 into a memory 29 under assignment to the measurement time.
- the corrected time-dependent intensity curve is, for example, to determine the layer thickness of a lacquer or powder layer applied to the test specimen 6 of measurement errors due to the relative speed of the test specimen 6 in relation to the optical part 1 and the segment detector by means of a test curve analyzer 30 connected downstream of the memory 29 11 corrected determinable.
- the segment detector 11 has a multiplicity of adjoining segments, the output signals of which summing elements and division elements can be fed in with a corresponding number of inputs.
- a larger range of relative speeds can now be determined by evaluating various intensity relationships formed in pairs, and a more complex movement path of the test specimen 6, such as, for example, in the case of a pendulum movement with horizontal and vertical components, can be evaluated.
- the use of the thermal radiation 8 generated directly in the test area 7 to determine the relative speed of the test body 6 ensures that the relative speeds in the test area 7 itself are also exactly detected.
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- General Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Power Engineering (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
Description
Claims
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
EP97931716A EP0912887A1 (en) | 1996-07-13 | 1997-07-04 | Signal processing unit of a device for photothermally testing a surface of a test piece |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19628391.4 | 1996-07-13 | ||
DE1996128391 DE19628391C1 (en) | 1996-07-13 | 1996-07-13 | Signal processing unit for photothermal surface testing device |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998002735A1 true WO1998002735A1 (en) | 1998-01-22 |
Family
ID=7799815
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/DE1997/001439 WO1998002735A1 (en) | 1996-07-13 | 1997-07-04 | Signal processing unit of a device for photothermally testing a surface of a test piece |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0912887A1 (en) |
DE (1) | DE19628391C1 (en) |
WO (1) | WO1998002735A1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3086087B1 (en) | 2015-04-20 | 2021-07-07 | OptiSense GmbH & Co. KG | Photo thermal measuring device and method for photo thermal measuring |
WO2021181375A1 (en) * | 2020-03-12 | 2021-09-16 | Elbit Systems Ltd. | System and method for determining a relative motion between two or more objects |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19747784A1 (en) * | 1997-10-29 | 1999-05-06 | Rothe Lutz Dr Ing Habil | Object identifying using thermal signature analysis and infrared sensor system |
DE19846995C2 (en) * | 1998-10-13 | 2000-11-30 | Fraunhofer Ges Forschung | Device for the contactless detection of test specimens |
DE102018108887A1 (en) * | 2018-04-13 | 2019-10-17 | ASCONA Gesellschaft für optische Messtechnik mbH | Anodization quality prediction system and method for such an arrangement |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4559819A (en) * | 1983-05-17 | 1985-12-24 | Mannesmann Aktiengesellschaft | Selecting the cut-off end portion of rolled sheet stock |
DE3820862A1 (en) * | 1988-06-21 | 1989-12-28 | Soelter Hans Joachim Dipl Phys | METHOD AND DEVICE FOR CONTACTLESS EXAMINATION OF SURFACES AND INTERNAL STRUCTURES OF A FIXED TEST BODY |
DE4343076A1 (en) * | 1993-12-16 | 1995-06-22 | Phototherm Dr Petry Gmbh | Device for photothermal testing of a surface |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3451254A (en) * | 1965-07-26 | 1969-06-24 | Automation Ind Inc | Nondestructive tester |
US4679946A (en) * | 1984-05-21 | 1987-07-14 | Therma-Wave, Inc. | Evaluating both thickness and compositional variables in a thin film sample |
-
1996
- 1996-07-13 DE DE1996128391 patent/DE19628391C1/en not_active Expired - Fee Related
-
1997
- 1997-07-04 EP EP97931716A patent/EP0912887A1/en not_active Ceased
- 1997-07-04 WO PCT/DE1997/001439 patent/WO1998002735A1/en not_active Application Discontinuation
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4559819A (en) * | 1983-05-17 | 1985-12-24 | Mannesmann Aktiengesellschaft | Selecting the cut-off end portion of rolled sheet stock |
DE3820862A1 (en) * | 1988-06-21 | 1989-12-28 | Soelter Hans Joachim Dipl Phys | METHOD AND DEVICE FOR CONTACTLESS EXAMINATION OF SURFACES AND INTERNAL STRUCTURES OF A FIXED TEST BODY |
DE4343076A1 (en) * | 1993-12-16 | 1995-06-22 | Phototherm Dr Petry Gmbh | Device for photothermal testing of a surface |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3086087B1 (en) | 2015-04-20 | 2021-07-07 | OptiSense GmbH & Co. KG | Photo thermal measuring device and method for photo thermal measuring |
WO2021181375A1 (en) * | 2020-03-12 | 2021-09-16 | Elbit Systems Ltd. | System and method for determining a relative motion between two or more objects |
IL273288B1 (en) * | 2020-03-12 | 2023-06-01 | Elbit Systems Ltd | System and method for determining a relative motion between two or more objects |
EP4118457A4 (en) * | 2020-03-12 | 2023-08-16 | Elbit Systems Ltd. | System and method for determining a relative motion between two or more objects |
Also Published As
Publication number | Publication date |
---|---|
EP0912887A1 (en) | 1999-05-06 |
DE19628391C1 (en) | 1997-09-11 |
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