Defect formation is a common problem in selective laser melting (SLM). This paper provides a review of defect formation mechanisms in SLM. It summarizes the recent research outcomes on defect findings and classification, analyzes formation mechanisms of the common defects, such as porosities, incomplete fusion holes, and cracks. The paper discusses the effect of the process parameters on defect...

The field-of-view (FOV) of a simple imaging system can be dramatically improved using a liquid crystal spatial light modulator (SLM). A SLM can be used to correct the off-axis aberrations that often limit the useful FOV of an imaging system giving near diffraction-limited performance at much larger field angles than would otherwise be possible. Foveated imaging refers to the variation in spatia...

We demonstrate the adverse influence of temporal fluctuations of the phase modulation of a spatial light modulator (SLM) display device on nanosecond laser micromachining. We show that active cooling of the display reduces the amplitude of these fluctuations, and we demonstrate a process synchronization technique developed to compensate for these fluctuations when applying the SLM to laser mate...

We present an approach capable of high-NA imaging in a lensless digital in-line holographic microscopy layout even outside the Gabor's regime. The method is based on spatial multiplexing at the sample plane, allowing a common-path interferometric architecture, where two interferometric beams are generated by a spatial light modulator (SLM) prior to illuminating the sample. The SLM allows phase-...

We demonstrate pulse shaping via arbitrary phase modulation with a reflective, 1×4096 element, liquid crystal spatial light modulator (SLM). The unique construction of this device provides a very high efficiency when the device is used for phase modulation only in a prism based pulse shaper, namely 85%. We also present a single shot characterization of the SLM in the spatial domain and a single...

This paper contains the Hadamard Transform in the SLM for the reduction of high peak to average power ratio (PAPR) in MIMOOFDM systems. In this technique, the input sequence is multiplied by a set of phase rotation vectors respectively and then applies the Hadamard Transform to the each resulting sequence based on SFBC. After that perform the Inverse Fast Fourier Transform in order to get the t...

To replace the film recording aspect of performing optical correlation, conventional real-time joint-transform correlation (JTC) optical systems make use of a spatial light modulator (SLM) located in the Fourier plane to record the joint-transform power spectrum (JPS) to achieve real-time processing. The use of an SLM in the Fourier plane, however, is a major drawback in these systems because S...

A spatial light modulator (SLM) and a pair of galvanometer-mounted mirrors (GMM) were combined into an optical tweezers setup. This provides great flexibility as the SLM creates an array of traps, which can be moved smoothly and quickly with the GMM. To optimize performance, the effect of the incidence angle on the SLM with respect to phase and intensity response was investigated. Although it i...

Communication is a key for facilitating multi-agent coordination on cooperative problems. In our previous work, we proposed Signal Learning (SL) and Signal Learning with Messages (SLM) by which agents learn local policies of communication and action simultaneously in MultiAgent Reinforcement Learning (MARL) framework. Our experimental results showed that both SL and SLM can improve the performa...