In order to shape a laser beam having a central lobe, the side lobes of which are suppressed, one embodiment of the present invention provides a laser beam shaping device 10 provided with: an annular phase element 100 which imparts, to a laser beam having a prescribed wavelength, a phase distribution which increases and decreases symmetrically around an axis; and a transmitting optical element 200 which has, on at least a portion of the surface, a projecting surface formed into an approximately conical lateral surface, and which is made from a material having a refractive index in a prescribed wavelength that is higher than that of the surrounding area. The annular phase element is used, for example, as a beam parameter product (BPP), and the transmitting optical element is used, for example, as an axicon. An embodiment of the present invention also provides an annular phase element for the laser beam shaping device.

Laser beam shaping device, removal machining device, and annular phase element

PURPOSE:To restrain subsidiary maximum while keeping a small spot diameter and a large depth characteristic by superposing Bessel beams having subsidiary maximum in different positions in amplitude so as to interfere with each other. CONSTITUTION:A laser beam L as a parallel light irradiates a concentric double ring opening 1, and the laser beam outgoing from the double ring opening 1 becomes two ring-like lights and pass through a lens 2, and they are superposed on the focal plane on the image side of the lens 2. The two ring-like lights become Bessel beams having mutually different diameters and distributions, and they interfere with each other to form a double Bessel beam due to being coherent. In this case, the parameter (6) is the ratio of diameters of two rings, and namely the parameter (f) is equal to the ratio of systems of two Bessel beams. This device is constituted so that the ratio (epsilon) of the two Bessel beams satisfy the relation; 0.3<=(epsilon)0.7.

Suzuki Masayuki

Papers

Double bessel generating method and device therefor