What is claimed is:
1. A device for fabricating a polarization insensitive long-period fiber grating, comprising:
a ultraviolet laser for irradiating a ultraviolet laser beam;
a ultraviolet polarizer for converting a polarization status of the ultraviolet laser beam into a linear polarization status in parallel along longitudinal direction of a fiber;
a lens for directing the ultraviolet laser beam passing through the ultraviolet polarizer into the fiber;
an amplitude mask for selectively passing the ultraviolet laser beam outputted from the lens onto the fiber; and,
a mount for holding both ends of the fiber, so that the outer circumferential surface of the fiber can be exposed to the ultraviolet laser beam outputted from the amplitude mask.
2. The device according to claim 1, wherein the mount comprises a pair of fixing units for holding both ends of the fiber.
3. The device according to claim 1, wherein the mount comprises a fixing unit for fixing one end of the fiber and a twisting unit for twisting the other end of the fiber.
4. The device according to claim 1, wherein the mount comprises a pair of rotating units for rotating both ends of the fiber in a predetermined direction.
5. A device for fabricating a polarization insensitive long period fiber grating, comprising:
a ultraviolet laser for irradiating a ultraviolet laser beam;
a ultraviolet polarizer for converting a polarization status of the ultraviolet laser beam into a linear polarization status in parallel along the longitudinal direction of a fiber;
a lens for directing the ultraviolet laser beam outputted from the ultraviolet polarizer into the fiber;
an amplitude mask for selectively passing the ultraviolet laser beam outputted from the lens and into the fiber;
a mount for holding both ends of the fiber, so that the outer circumferential surface of the fiber can be exposed to the ultraviolet laser beam outputted from the amplitude mask; and,
a mirror for reflecting the ultraviolet laser beam outputted from the amplitude mask back to the outer circumferential surface of the fiber.
6. The device according to claim 5, wherein the mount comprises a pair of fixing units for respectively fixing both ends of the fiber.
7. The device according to claim 5, wherein the mount comprises a fixing unit for fixing one end of the fiber and a twisting unit for twisting the other end of the fiber.
8. The device according to claim 5, wherein the mount comprises a pair of rotating units for rotating both ends of the fiber in a predetermined direction.
9. A method for passing light through an amplitude mask to create interference pattern into a fiber, the method comprising the steps of:
generating a ultraviolet laser beam;
converting a polarization of the ultraviolet laser beam into a linear polarization in a parallel relationship with the fiber;
directing the converted ultraviolet laser beam through an amplitude mask and into the fiber, such that when the converted ultraviolet laser beam is transmitted through the amplitude mask and exposed to along the fiber, an interference is formed which extends through the fiber.
10. The method of claim 9, wherein the positioning and orientation of the fiber is stationery when the converted ultraviolet laser beam is transmitted through the amplitude mask.
11. The method of claim 9, further comprising the step of rotating one of the fiber at a predetermined rate when the converted ultraviolet laser beam is transmitted trough the amplitude mask.
12. The method of claim 9, further comprising the step of rotating both ends of the fiber in a predetermined direction when the converted ultraviolet laser beam is transmitted trough the amplitude mask.
13. The method of claim 9, further comprising the step of placing a reflective unit for reflecting the converted ultraviolet laser beam outputted from the amplitude mask back to the unexposed surface of the fiber.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A metal wire rod for forming slide fastener coupling elements, having a substantially Y-shaped section, which has a head part and a pair of leg parts extending from the head part through a crotch part, wherein the crotch part is formed with a flat face; and three or more bent portions, which an inner surface of each of the leg parts is bent inward, are formed successively in an extending direction of the leg parts from the crotch part to a pawl part at a front end of each of the leg parts.
2. The metal wire rod for forming slide fastener coupling elements according to claim 1, wherein a gap between inner faces of the pawl parts narrows gradually from proximal end portions of the pawl parts toward front end portions thereof.
3. The metal wire rod for forming slide fastener coupling elements according to claim 1, wherein a bent portion located between an inner face of the leg part and an inner face at the proximal end portion of the pawl part exists outside a straight line which is parallel to a straight line connecting a middle point on a straight line connecting front ends of the right and left pawl parts with a center of a section of the head part and which passes through the front end of the pawl part.
4. The metal wire rod for forming slide fastener coupling elements according to claim 1, wherein an opening angle between the pair of leg parts is 75\xb0 to 85\xb0.
5. The metal wire rod for forming slide fastener coupling elements according to claim 1, wherein an outer side face of a joint portion of the head part and the leg part has a bulging portion which bulges outward from the outer side face.
6. The metal wire rod for forming slide fastener coupling elements according to claim 1, wherein hardness of at least a coupling protrusion forming region of the head part is smaller than that of the leg part.