Abstract: A method for producing a polytetrafluoroethylene particle, which includes subjecting tetrafluoroethylene to suspension polymerization in an aqueous medium to prepare a suspension-polymerized particle of polytetrafluoroethylene, washing and then crushing the suspension-polymerized particle or crushing the suspension-polymerized particle with washing to prepare a crushed particle, dehydrating the crushed particle to prepare a crushed particle having a water content of 40% by mass or less, and subjecting the dehydrated crushed particle to heat treatment to produce a polytetrafluoroethylene particle.

Abstract: A method for producing a polytetrafluoroethylene powder, which includes subjecting tetrafluoroethylene to suspension polymerization in an aqueous medium to prepare a suspension-polymerized particle of non melt-processible polytetrafluoroethylene, drying the suspension-polymerized particle to prepare a dry particle, subjecting the dry particle to fluorine radical treatment to prepare a fluorine radical-treated particle, and crushing the fluorine radical-treated particle to produce a polytetrafluoroethylene powder. Also disclosed is a polytetrafluoroethylene formed article obtained by forming the polytetrafluoroethylene powder, as well as a polytetrafluoroethylene compression-molded article obtained by compression molding the polytetrafluoroethylene powder.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method having a displacement acquiring step of acquiring a displacement between a point on the cutting line and one end of the cutting line in the object while irradiating the object with a second laser beam, converged by a lens, for measuring the displacement of a main surface of the object; and a position setting step of setting an initial position for holding the lens with respect to the main surface of the object according to the acquired displacement, and holding the lens at thus set initial position.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam is provided. This laser processing method comprises a displacement acquiring step (S07 to S11) of irradiating an object to be processed with a rangefinding laser beam for measuring a displacement of a main surface of the object while converging the laser beam with a lens and acquiring the displacement of the main surface along a line to cut while detecting reflected light reflected by the main surface in response to the irradiation; and moves the processing objective lens and the object relative to each other along the main surface, while adjusting the gap between the processing objective lens and the surface according to the displacement acquired by the displacement acquiring step, thereby forming the modified region along the line to cut.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A shutter unit capable of preventing the scattering of the laser beam upon closing the optical path of the laser beam and capable of being miniaturized, and a laser processing device employing such a shutter unit. In a shutter unit 1, when the optical path of the laser beam L is opened, a rotating member 57 is rotated around an axis line ?, and an opening 61 is positioned on an optical axis ? so as to pass the laser beam L therethrough. Meanwhile, when the optical path of the laser beam L is closed, the rotating member 57 is rotated and a reflective surface 62 is positioned on the optical axis ? so as to reflect the laser beam L. Here, since the reflected laser beam L is absorbed by an optical absorption member 63, it is possible to prevent the scattering of the laser beam L when the optical path of the laser beam L is closed.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided. This laser processing method comprises a displacement acquiring step (S06 and S07) of acquiring a displacement between a point on the line to cut and one end of the line to cut in the object while irradiating the object with a second laser beam, converged by a lens, for measuring the displacement of a main surface of the object; and a position setting step (S08 and S09) of setting an initial position for holding the lens with respect to the main surface of the object according to the acquired displacement, and holding the lens at thus set initial position.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam in end parts of an object to be processed is provided.

Abstract: A laser processing method which can efficiently perform laser processing while minimizing the deviation of the converging point of a laser beam is provided. This laser processing method comprises a displacement acquiring step (S07 to S11) of irradiating an object to be processed with a rangefinding laser beam for measuring a displacement of a main surface of the object while converging the laser beam with a lens and acquiring the displacement of the main surface along a line to cut while detecting reflected light reflected by the main surface in response to the irradiation; and moves the processing objective lens and the object relative to each other along the main surface, while adjusting the gap between the processing objective lens and the surface according to the displacement acquired by the displacement acquiring step, thereby forming the modified region along the line to cut.

Abstract: A shutter unit capable of preventing the scattering of the laser beam upon closing the optical path of the laser beam and capable of being miniaturized, and a laser processing device employing such a shutter unit. In a shutter unit 1, when the optical path of the laser beam L is opened, a rotating member 57 is rotated around an axis line ?, and an opening 61 is positioned on an optical axis ? so as to pass the laser beam L therethrough. Meanwhile, when the optical path of the laser beam L is closed, the rotating member 57 is rotated and a reflective surface 62 is positioned on the optical axis ? so as to reflect the laser beam L. Here, since the reflected laser beam L is absorbed by an optical absorption member 63, it is possible to prevent the scattering of the laser beam L when the optical path of the laser beam L is closed.