Lock-in common-mode rejection demodulation: Measurement technique and applications to thermal-wave detection. Experimental

2000 ◽  
Vol 71 (6) ◽  
pp. 2445-2451 ◽  
Author(s):  
Stefano Paoloni ◽  
Lena Nicolaides ◽  
Andreas Mandelis
Keyword(s):  
Measurement Technique ◽  
Thermal Wave ◽  
Common Mode ◽  
Wave Detection ◽  
Lock In

scholarly journals Nonlinearity Measurements Using Alternating Current

1978 ◽  
Vol 5 (2) ◽  
pp. 91-98 ◽  
Author(s):  
Vladimír Ryšánek ◽  
Carlo Corsi ◽  
Arnaldo d'Amico
Keyword(s):  
Frequency Band ◽  
Measurement Technique ◽  
Alternating Current ◽  
Noise Measurement ◽  
Wide Frequency Band ◽  
Semiconductor Structures ◽  
Different Types ◽  
Homogeneous Structures ◽  
Lock In

The nonlinearity measurement technique described uses an adapted conventional lock-in-amplifier. This technique enables us to measure small nonlinearities over a wide frequency band and is more sensitive than the 1/f noise measurement used to detect non-homogeneous structures in conductors, resistors and semiconductor components. Results illustrating uses of this method are presented for different types of resistor and semiconductor structures.

High-Resolution Quadrature Photopyroelectric Spectroscopy of a-Si:H Thin Films Deposited on Silicon Wafers

1995 ◽  
Vol 49 (6) ◽  
pp. 819-824 ◽  
Author(s):  
Jun Shen ◽  
Andreas Mandelis ◽  
Andreas Othonos ◽  
Joseph Vanniasinkam
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thermal Wave ◽  
Incident Radiation ◽  
Surface Films ◽  
Si Substrates ◽  
Wafer Substrate ◽  
Ir Transmission ◽  
Ft Ir ◽  
Lock In

The recently developed photothermal technique of quadrature photopyroelectric spectroscopy (Q-PPES) has been applied to measurements of amorphous Si thin films deposited on crystalline Si substrates. Direct, meaningful comparisons have been made between purely optical transmission in-phase (IP-PPES) spectra, and purely thermal-wave sub-gap spectra with the use of a novel noncontacting PPES instrument to record lock-in in-phase and quadrature spectra, respectively. FT-IR transmission spectra have also been obtained for a comparison with this IP-PPES optical method. The results of the present work showed that the FT-IR method performs the worst in terms of spectral resolution of thin films and sub-bandgap defect/impurity absorptions inherent in the Si wafer substrate. The optical IP-PPES channel, however, albeit more sensitive than the FT-IR technique, fails to resolve spectra from surface films thinner than 2100 Å, but is sensitive to sub-bandgap absorptions. The thermal-wave Q-PPES channel is capable of resolving thin-film spectra well below 500 Å thick and exhibits strong signal levels from the crystalline Si sub-bandgap absorptions. Depending on the surface thin-film orientation toward, or away from, the direction of the incident radiation, the estimated minimum mean film thickness resolvable spectroscopically by Q-PPES is either 40 Å or 100 Å, respectively.

Lock‐in rate‐window thermomodulation (thermal wave) and photomodulation spectrometry

1992 ◽  
Vol 63 (5) ◽  
pp. 2977-2988 ◽  
Author(s):  
Andreas Mandelis ◽  
Zhuohui Chen
Keyword(s):  
Thermal Wave ◽  
Lock In ◽  
Rate Window

Recent advances in thermal wave detection and ranging for non-destructive testing and evaluation of materials

2013 ◽  
Author(s):  
Ravibabu Mulaveesala ◽  
V. S. Ghali ◽  
Vanita Arora ◽  
Juned A. Siddiqui ◽  
Amarnath Muniyappa ◽  
...  
Keyword(s):  
Thermal Wave ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Wave Detection ◽  
Recent Advances ◽  
Non Destructive ◽  
Testing And Evaluation
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