Optical microcavities support Whispering Gallery Modes (WGMs) with a very high quality factor Q. However, WGMs typically display a far-field isotropic emission profile and modifying this far-field profile without spoiling the associated high Q remains a challenge. Using a 2D annular cavity, we present a procedure capable to achieve these two apparently conflicting goals. With the correspondence between the classical and the wave picture, properties of the classical phase space shed some light on the characteristics of the wave dynamics. Specifically, the annular cavity has a well separated mixed phase space, a characteristic that proves to be of crucial importance in the emission properties of WGMs. While the onset of directionality in the far-field may be achieved through parametric deformation [1] of the distance cavity-hole centers, d , this contribution presents a method to control the emission profile via a second parameter, the hole radius r 0 . The influence of the classical dynamics to control and predict the field emission will be demonstrated.

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This paper presents how to compute the envelope of a total focusing method (TFM) image and the benefits of using this TFM envelope as part of a code-compliant solution. The TFM envelope is obtained by computing the norm of two different TFM images; namely, a first TFM image computed using the standard acquired full matrix capture (FMC), and a second TFM image computed using the Hilbert-transformed FMC. The resulting TFM envelope image provides a better basis for the amplitude-based sizing technique, as it is more robust to amplitude variation compared with a standard oscillatory TFM image at an identical grid resolution. Therefore, with respect to the standard oscillatory TFM, a coarser grid resolution can be set for the TFM envelope, consequently reducing the total amount of computation effort and ultimately increasing the resulting acquisition rate.

Time of flight diffraction (TOFD) is considered a reliable non-destructive testing method for the inspection of welds using a pair of single-element probes. On the other hand, ultrasonic phased array imaging has been continuously developed over the last couple of decades, and now features powerful algorithms, such as the total focusing method (TFM) and its multi-view approach to rendering detailed images of inspected parts. This article focuses on a different implementation of the TFM algorithm, relying on the coherent summation of the instantaneous signal phase. This approach presents a wide range of benefits, such as removing the need for calibration, and is highly sensitive to defect tips. This study compares the sizing and localization capabilities of the proposed method with the well-known TOFD. Both instantaneous phase algorithm and TOFD do not take advantage of the signal amplitude. Experimental tests were performed on a ¾″-thick steel sample with crack-like defects at different angles. Phase-based imaging techniques showed similar characterization capabilities as the standard TOFD method. However, the proposed method adds the benefit of generating an easy-to-interpret image that can help in localizing the defect. These results pave the way for a new characterization approach, especially in the field of automated ultrasonic testing (AUT).

As seamless tube manufacturers push quality requirements for their products, automated phased array Rotating Tube Inspection Systems (RTIS) are now required to provide continuous NDE detection performances over a wide angular range of oblique flaws. One major impact of this new reality is a paradigm shift for the calibration method driven by the requirement to meet homogeneous detection over broad oblique flaw angle intervals, whereas standard practice only requires calibration at specific discrete angles. An innovative method specifically designed to obtain high productivity and homogeneous inspection measurements over an oblique flaw range extending from -45 to 45 degrees is presented. Experimental results from the application of the method on various tubes presenting multiple artificial flaws support the quantitative performance evaluation.