DETECTION OF DENSE, OVERLAPPING, GEOMETRIC OBJECTS.

Using a unique data collection, we are able to study the detection of dense geometric objects in image data where object density, clarity, and size vary. The data is a large set of black and white images of scatterplots, taken from journals reporting thermophysical property data of metal systems, whose plot points are represented primarily by circles, triangles, and squares. We built a highly accurate single class U-Net convolutional neural network model to identify 97 % of image objects in a defined set of test images, locating the centers of the objects to within a few pixels of the correct locations.

Time-Resolved Absorptance and Melt Pool Dynamics during Intense Laser Irradiation of a Metal.

High-irradiance lasers incident on metal surfaces create a complex, dynamic process through which the metal can rapidly change from highly reflective to strongly absorbing. Absolute knowledge of this process underpins important industrial laser processes such as laser welding, cutting, and metal additive manufacturing. Determining the time-dependent absorptance of the laser light by a material is important, not only for gaining a fundamental understanding of the light-matter interaction but also for improving process design in manufacturing.

Experimental observation of extremely weak optical scattering from an interlocking carbon nanotube array.

We experimentally demonstrate a nearly wavelength-independent optical reflection from an extremely rough carbon nanotube sample. The sample is made of a vertically aligned nanotube array, is a super dark material, and exhibits a near-perfect blackbody emission at T=450 K-600 K. No other material exhibits such optical properties, i.

Very black infrared detector from vertically aligned carbon nanotubes and electric-field poling of lithium tantalate.

Vertically aligned multiwall carbon nanotubes were grown by water-assisted chemical vapor deposition on a large-area lithium tantalate pyroelectric detector. The processing parameters are nominally identical to those by which others have achieved the "world's darkest substance" on a silicon substrate. The pyroelectric detector material, though a good candidate for such a coating, presents additional challenges and outcomes.