# US 4,391,519 A · Axis-monitoring apparatus for a laser beam > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,519 A - Document ID: US4391519A - Status: Granted - Kind: A - Application number: 06/186,731 - Filed: 1980-09-12 - Granted: 1983-07-05 - Earliest claimed: 1979-09-12 - Assignees: Hitachi, Ltd. - Inventors: Kouji Kuwabara; Hiroyuki Sugawara; Toshiharu Shirakura; Kouji Sasaki; Satoshi Takemori - Web page: https://patentgrep.com/patent/US4391519A ## CPC - B23K 26/02: Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam - B23K 26/035: Aligning the laser beam (automatically B23K26/042) - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM ## Abstract A laser beam axis monitoring apparatus which includes a laser oscillator generating a laser beam and a light generator for generating a light for monitoring an axis of the laser. The light from the light generator is split into ring-shaped light and reflected or lead into the laser oscillator. The light in the laser oscillator is reflected by a total reflection mirror and passes out of the oscillator so that the axis of the laser beam and axis of the light coincide with each other. ## Claims ### Claim 1 A laser beam axis-monitoring apparatus, the apparatus comprising a laser oscillating means for generating a laser beam, and a light generator means for generating a light for monitoring an axis of the laser beam, characterized in that directing means are arranged between the laser oscillator means and the light generator means for directing the light from the generator means into the laser oscillator means, said directing means includes a ring-shaped mirror having an opening at a center thereof, and concave mirror means are disposed in the laser oscillator means for reflecting the light from the ring-shaped mirror out of the laser oscillator means in such a manner that the axis of the laser beam and axis of the light are coincident with both the light and said laser beam from said laser oscillator means passing through said opening of said ring-shaped mirror. ### Claim 2 (depends on 1) The apparatus according to claim 1, characterized in that a beam splitter means is arranged between the light generator means and the directing means for transforming the light into a ring-shaped light. ### Claim 3 (depends on 2) The apparatus according to claim 2, characterized in that the hole has a 45.degree. elliptical shape. ### Claim 4 (depends on 1) The apparatus according to claim 1, characterized in that focusing means are provided for focusing the light and laser beam. ### Claim 5 A laser beam axis-monitoring apparatus comprising a laser oscillator means for generating a laser beam, a mirror disposed at one end of the oscillator means, a light generator means for generating a light for monitoring an axis of the laser beam, a beam splitter means for transforming the light into ring-shaped light, and a ring-shaped mirror arranged between the laser oscillator means and the light generator means, the ring-shaped mirror having a hole in a center thereof, the ring-shaped light from the beam splitter means being reflected by the ring-shaped mirror into the laser oscillator means from an opposite end of the laser oscillator means and being reflected by the mirror disposed therein such that the reflected light and the laser beam pass from the laser oscillator means through the hole in the ring-shaped mirror. ### Claim 6 (depends on 5) An apparatus according to claim 5, wherein the hole of the ring-shaped mirror has a 45.degree. elliptical shape. ### Claim 7 (depends on 6) An apparatus according to claim 6, wherein said light generator means is a He-Ne laser. ### Claim 8 (depends on 5) An apparatus according to claim 5, wherein focusing means are provided for focusing the light and laser beam passing through the hole of the ring-shaped mirror. ### Claim 9 (depends on 1) An apparatus according to one of claims 1, or 5, wherein said light generator means is a He-Ne laser. ### Claim 10 (depends on 1) An apparatus according to claim 1, characterized in that means are arranged between the light generator means and the laser oscillator means for splitting the light from the light generator means. ### Claim 11 A laser beam axis-monitoring apparatus, the apparatus comprising a laser oscillating means for generating a laser beam, and a light generator means for generating a light for monitoring an axis of the laser beam, characterized in that means are arranged between the laser oscillator means and the light generator means for directing the light from the generator means into the laser oscillator means, mirror means are disposed in the laser oscillator means for reflecting the light from the generator means out of the laser oscillator means with the axis of laser beam and axis of the light being coincident, means are arranged between the light generator means and the laser oscillator means for splitting the light from the light generator means, said directing means includes a ring-shaped mirror having a hole at a center thereof such that the light from the light splitting means is reflected by the ring-shaped mirror and directed into the laser oscillator means, both the light and laser beam pass from the laser oscillator means through the hole of the ring-shaped mirror, the light splitting means is a ring converter which includes a rotary drum and a pair of reflection mirrors arranged in the rotary drum at a predetermined angle with respect to each other, and in that light from the light generator means is reflected by the reflection mirrors and becomes a light rotating about a center axis of the rotary drum.