Results 141 to 150 of about 670 (184)
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Absorption measurements in optical coatings by lock-in thermography
Applied Optics, 2017We evaluate and apply lock-in thermography as a method to quantitatively evaluate absorption losses of optical coatings. The principle of the method consists of applying periodically modulated laser intensity on the coatings and to monitor the periodic surface temperature evolution with an infrared camera.
Liu, Feng, Gallais, Laurent
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3D Hot-Spot Localization by Lock-In Thermography
EDFA Technical Articles, 2019Abstract This article describes a form of lock-in thermography that achieves 3D localization of thermally active defects in stacked die packages. In this approach, phase shifts associated with thermal propagation delay are analyzed as a function of frequency.
Sebastian Brand, Frank Altmann
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Defect detectability based on square wave lock-in thermography
Applied Optics, 2022A lock-in thermography technique based on a periodical square wave is used to detect stainless steel plates with defects. Combining a neural network with lock-in thermography, an image processing technique is proposed, and the results are compared with traditional image processing methods.
Pengfei, Zhu +3 more
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Lock-in thermography for nondestructive evaluation of materials
International Journal of Thermal Sciences, 1998Abstract Photothermal radiometry allows for remote measurement of local harmonic heat transport where the phase angle (between remote optical energy deposition and resulting temperature modulation) is sensitive to subsurface features or defects.
Datong Wu, Gerd Busse
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Lock-in thermography with a focal plane array
Measurement Science and Technology, 2003A focal plane array is used in a lock-in infrared thermography set-up. Two procedures are used to verify the validity of the phase lags given by the numerical lock-in. The first one makes use of a body with a periodically modulated emission in near and middle infrared.
Horny, Nicolas, Lannoy, Bruno
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Phase-Locked Image Acquisition In Thermography
SPIE Proceedings, 1989Phase-locked detection is a very useful instrumentation technique. It can be used whenever the desired signal is phase-coherent with another reference signal. Very frequently, the reference signal is, or can be derived from, the periodic external stimulus which is responsible for the signal in the first place.
P. K. Kuo +3 more
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Infrared Physics and Technology, 2002
This paper describes several experimental investigations of newly developed thermographic NDT techniques based on the transient temperature measurements. Several experimental results of the pulse heating thermographic NDT and the lock-in thermographic NDT are shown.
Takahide Sakagami, Shiro Kubo
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This paper describes several experimental investigations of newly developed thermographic NDT techniques based on the transient temperature measurements. Several experimental results of the pulse heating thermographic NDT and the lock-in thermographic NDT are shown.
Takahide Sakagami, Shiro Kubo
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Lock-in Thermography Characterization of Photothermal Transparent Thin Films
2025 IEEE International Instrumentation and Measurement Technology Conference (I2MTC)This study evaluates the capabilities of a new Lock-in Thermography device for characterizing photothermal thin films. Lock-in Thermography, a sensitive imaging technique, is used to detect thermal variations, particle aggregation, and material inhomogeneities.
Gabriella Butler +5 more
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Parameters in lock-in thermography of CFRP laminates
Materials Testing, 2016AbstractActive thermography with lock-in excitation is a nondestructive testing method that is also feasible for testing of carbon fiber reinforced polymers (CFRP). For validating the method extensive investigations were done during a research project in order to advance a standardization process. The most important parameters of optical and ultrasonic
Philipp Myrach +3 more
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LOCK-IN THERMOGRAPHY IN DETECTION OF OSMOTIC DAMAGE
2016The lock-in thermography is a powerful NDT method capable of vizualizing osmotic processes in composite structure where conventional aproach is inaccurate.
Domazet, Željko +2 more
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