Infrared thermography is a whole field, noncontact, and nondestructive characterization technique widely used for the investigation of subsurface features in various solid materials (conductors, semiconductors, and composites). Increased demand for greater subsurface probing in thermal nondestructive testing is often thwarted by the probing high peak power into the sample, for which narrow pulse operation is usually used. The technique of pulse compression offers a means of increasing the average power available to illuminate test specimen without any loss of the depth resolution needed for the tactical requirements. This is accomplished by transmitting a wide pulse in which the incident heat flux is frequency modulated and then, by proper signal processing methods, causing a time compression of the received signal to a much narrower pulse of high effective peak power. For the demonstration, a mild steel sample having flat bottom holes at various depths is introduced and detection capability of the proposed approach has been studied.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1063/1.2976673 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
We demonstrate a widely spaced, stabilized, and self-referenced opto-electronic oscillator driven electro-optic modulator based optical frequency comb. Using an ultra-stable Fabry-Perot etalon as a stable reference, we simultaneously stabilize a CW laser and generate a low noise and stable RF oscillation used to drive an electro-optic comb. In such a manner, the Fabry-Perot etalon pins both the carrier-envelope-offset frequency ( ) and the repetition rate of the comb in place ( ), eliminating the need for an external RF oscillator.
View Article and Find Full Text PDFThermal engineering can be used to exploit absorption in a silicon optical cavity. In this work, the steady state profile of the heat generated by absorption is shaped and used to generate a dynamic heterostructure in a weakly confined silicon optical cavity. This is demonstrated in an edge defect photonic crystal optomechanical cavity to produce phonon lasing and sub-GHz optical pulsing with photon-phonon cooperativity of 0.
View Article and Find Full Text PDFA coherent optical frequency comb (OFC) with suppressed linewidth is demonstrated based on the spectral broadening of a directly modulated semiconductor microcavity laser with self-injection locking. Due to the high electro-optical response, the directly modulated microcavity laser provides a 10-GHz-spaced seeding OFC with 9 comb teeth in a 10 dB flatness window. Besides, an optical feedback fiber loop with two sub-loops is introduced to reduce the linewidth of the microlaser and suppress the undesired longitudinal modes.
View Article and Find Full Text PDFWe demonstrate a dual-crystal Yb:YAG bulk regenerative amplifier that delivers a hundred-watt average power and millijoule-class pulse energy. The repetition rate of the presented laser is tunable from 50 kHz to 300 kHz, with the highest pulse energy and laser power of 1.9 mJ and 108.
View Article and Find Full Text PDFWe demonstrated what is believed to be the first 1.2 GHz nonlinear polarization rotation stretched-pulse mode-locked Yb:fiber laser with a compact design and innovative components. With a compact Faraday rotation angle has been used in NPR mode-locked lasers, and we find that incomplete isolation of backward-propagating light does not hinder self-starting.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!