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This research aims to solve online collision avoidance problem of two manipulators with independent controller. Since industrial robot controller is a closed commercial system, trajectory generation part of robot controlling is always proprietary or unknown. Thus, this paper proposes a collision avoidance system of two manipulators which are controlled by point-to-point (PTP) commands, in condition that the internal of robot controller is unknown and unchangeable. Based on this condition, collision avoidance is supposed to be realized by online scheduling of these PTP controlling commands. This paper proposes the collision avoidance method that assumes the three-dimensional common workspace between two manipulators can be partitioned into many subregion elements. And with managing these subregion elements, which are occupied by robot motion, PTP commands are scheduled to adjust execution timing for collision avoidance. A deadlock problem caused by the partition of the workspace is also taken into consideration in the method. And the effectiveness and efficiency of the method have been verified by simulations and experiments.

This letter reports the CW red laser radiation at 659.5 nm by intracavity frequency doubling a side pumped Nd:YAG laser with a KTP crystal (type II phase match, Θ=59.8°, Φ=0°). The thermal lens effect related to the laser crystal is analyzed and parameters of the three-mirror folded cavity are calculated. To enhancing the high gain at 1319 nm of the operating wave of Nd:YAG, the reflectivity of the mirrors is designed, and the red laser radiation at 659.5 nm is achieved by intracavity frequency-doubling. The generation of 1.2 W of the CW red laser beam is obtained with 260 W pumped power.

High-power red laser are of great interest in the fields of medical application, laser display and also as a pumping source for tunable lasers such as Cr:LiSAF. This letter reports the generation of a 12W Q-CW red laser beam by intracavity frequency-doubling of a Nd:YAG laser operating at 1.3μm with a KTP crystal. A laser module that consisting of a Nd:YAG rod side-pumped by thirty 20W LDs of a triangle radial pump geometry, a acousto-optic Q switch and a KTP crystal were used in the experiment. Because the efficiency of SHG is sensitive to the type II phase-matching angles of KTP, we calculate the value of phase-matching angles according to several of Sellemier equations of KTP, and modify the phase-matching angles to θ=59.9° and φ=0° by experiment. The maximum average power of 12W of red laser is achieved at 10KHz when the pump power of LDs is about 470W.

High power laser-diode-pumped 532nm laser sources (including continuous wave and high repetition rate operation) are directly used for precise processing of metals and plastics. Furthermore, high power green laser will be used in some fields such as ocean exploration, laser probe and underwater communication. Recently, we reported a 110W diode-side-pumped Nd:YAG intracavity frequency doubled high stability 532nm laser. In the experiment, we found that the average output power of second harmonic fluctuated acutely with the variety of pumping current. Moreover, the length of arms between the mirrors were very sensitive to this cavity. We consider that one of the reason is the focus length of thermal lens of Nd:YAG rod alter with the variational pumping current, which makes the cavity be unstable. We consider the KTP crystal as a thin lens for its short length. As thermal lensing effect of the Nd:YAG rod is quite severe, so we consider it as thermal lensing medium. By ray matrix methods, we have obtained the stable regions and beam waist radii distribution in the flat-concave cavity. In our experiment, we used a pump head consisting of 80 diode bars with pentagon pump model and employed flat-concave cavity structure in order to achieve high stability output and increase output power. The total cavity length is 505mm. By using an acousto-optic Q-switching with high diffraction loss and the KTP crystal which is type II phase matching, 110 W high stability 532nm laser is achieved. The experimental result is in good agreement with the calculation.

Disk fiber laser is a novel fiber laser. The pumping scheme of such type of fiber laser is side pumping by LD arrays and the pumping scale is large in comparison with the core pumping manner in a typical clad pumping scheme. More pumping power could be coupled into the disk and higher output power could be achieved. To optimize the system of disk fiber laser, it is necessary to analyze the parameter of each part of it. In this paper, the configuration factors that influence the pumping efficiency of disk fiber laser were analyzed and propagation of the rays in disk fiber laser was simulated using the method of BPM. In the process of simulation, the fiber was treated as cylindrical lens. The optimal position of pump resource is obtained with a fixed size of the fiber cross section.