Abstract: A laser apparatus which has a laser resonator 2 for emitting a laser beam 8, an optical fiber 23, on which the laser beam 8 transmitted from the laser resonator 2 through a beam transmission optical path is made incident, for transmitting the laser beam 8 to a workpiece, a measurement and adjustment jig 44 for measuring laser beam output of an annular pattern occurring in the periphery of a beam pattern of the laser beam 8 emitted from the optical fiber 23, and a fiber incidence section 22 for adjusting incidence of the laser beam 8 on the optical fiber 23 based on output from the measurement and adjustment jig 44.

Abstract: An ink jet printer serves to solve a problem that ink is not normally discharged when bubbles are present in ink contained in a ink chamber of a print head. The ink jet printer performs normal discharge of ink by detecting bubbles contained in ink and carrying out an optimum head recovery operation, so that stable and high-quality printed matter can be obtained. According to a bubble detecting circuit and method employed in this ink jet printer, the impedance of the piezoelectric element of the head is first measured at given frequencies. Then, impedance versus frequency characteristics are obtained. Subsequently, it is determined, based on the impedance versus frequency characteristics, whether or not a bubble adheres to the piezoelectric element.

Abstract: When bubbles affecting the performance of spitting ink are generated in an ink reservoir, the bubbles are completely removed to attain a state full of ink without bubbles of the ink reservoir. An inkjet head comprising an ink tank, an ink reservoir having a nozzle array, and an ink supply path for introducing ink from the ink tank into the ink reservoir is characterized in that, with the ink supply path being closed and with a vent hole for making the ink reservoir in communication with the external being open, an ink suction device introduces the outside air via the vent hole into the ink reservoir to which negative pressure is applied by the suction of ink, while ink in the ink reservoir is sucked out to the external via a suction path.