Thermal measuring and testing – Thermal testing of a nonthermal quantity
Patent
1996-05-08
1998-09-08
Gutierrez, Diego F. F.
Thermal measuring and testing
Thermal testing of a nonthermal quantity
374 5, 374130, 374161, 374 7, G01N 2500
Patent
active
058036067
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a device for photothermic testing of a surface, and more particularly to photothermic testing of a moving test specimen. The present invention includes an illuminating device capable of generating an intensity-modulated excitation radiation and an optical system for applying the excitation radiation to a surface of a moving test specimen. The system is capable of passing thermal radiation given off by a measuring area to a detector, which thermal radiation is captured in an angular area enlarged relative to the direct field of view of the detector. The optical system features a reflection device having a reflection surface which allows coaxial alignment of the excitation radiation emitted from the illuminating device with the thermal radiation passed to the detector. The present invention features an imaging device disposed between the surface of the test specimen and the detector. The imaging device collects that portion of the thermal radiation emitted from the test area situated in the focal area of the imaging device.
A device of the general category of the present invention is previously known from DE 39 13 474 A1. DE 39 13 474 A1 discloses a neodym/YAG laser illuminating device which allows focusing an intensity-modulated excitation radiation in a parallel beam. The optical system comprises a first and second deflection mirror and an imaging lens, which direct the excitation radiation to a surface of a test specimen within a test area. The first deflection mirror deflects the excitation radiation exiting from the neodym/YAG laser onto the second deflection mirror. Thermal radiation in the infrared spectral range between about 2 .mu.m and 5 .mu.m is given off by the surface of the test specimen and such radiation is of a longer wavelength than the excitation radiation. Some of thermal radiation emitted from the test specimen can be transmitted from the measuring area to the imaging lens and further transmitted as a parallel beam. The portion of the thermal radiation passing through the imaging lens is deflected by the second deflecting mirror, which reflects both the excitation radiation and the thermal radiation, and then passes through the first deflecting mirror, which is partially translucent for the spectral range of the thermal radiation. The thermal energy then falls on a third deflecting mirror of the optical system, which third mirror is optimized for the spectral range of the thermal radiation. The part of the thermal radiation deflected by the third deflecting mirror falls via a focusing detector lens on a detector.
In this device, the second deflecting mirror is fashioned as a movable scanner, so that the excitation radiation can sweep the surface along a predetermined, or "meandering," measuring path. Because the thermal radiation transmitted by the imaging lens and the excitation radiation are coaxially aligned, the measuring area substantially matches the test area. The imaging lens is traversed by both the excitation radiation and the thermal radiation and is able to transmit both the excitation radiation and the thermal radiation. The imaging lens preferably has a coating on the side of the lens surface which faces the test surface. This coating acts as a window for a spectral range of about 2 .mu.m to 5 .mu.m, but is not able to transmit smaller wavelengths, such as the 1 .mu.m wavelength of the excitation radiation. The first deflecting mirror is maximally reflective for the spectral range of the excitation radiation and at the same time, maximally able to transmit the spectral range of the thermal radiation.
While DE 39 13 474 A1 discloses an imaging lens which functions as a double lens for the excitation radiation and the thermal radiation and therefore captures a large part of the thermal radiation reflected by the surface, the fabrication expense for such an imaging lens is relatively high. Furthermore, using a semipermeable dielectric, or dichroic mirror as the first deflection mirror causes inevitable losses both o
REFERENCES:
patent: 3142755 (1964-07-01), Leroux
patent: 4075493 (1978-02-01), Wickersheim
patent: 4647220 (1987-03-01), Adams et al.
patent: 4679946 (1987-07-01), Rosencwaig et al.
patent: 4729668 (1988-03-01), Angel et al.
patent: 4874251 (1989-10-01), Thomas et al.
patent: 4908835 (1990-03-01), Nishiuchi et al.
patent: 5036194 (1991-07-01), Hazel
patent: 5052816 (1991-10-01), Nakamura et al.
patent: 5131758 (1992-07-01), Heyman et al.
patent: 5350236 (1994-09-01), Thakur et al.
patent: 5358333 (1994-10-01), Schmidt et al.
patent: 5374122 (1994-12-01), Devitt et al.
patent: 5433106 (1995-07-01), Matsumura et al.
Petry Harald
Prekel Helmut
Gutierrez Diego F. F.
Phototherm Dr. Petry GmbH
LandOfFree
Surface photothermic testing device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Surface photothermic testing device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface photothermic testing device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1275874