Patent ID: 9027523
Filing Date: 2015-05-12
Classification: F02P

Abstract:
1. A laser ignition apparatus comprising: an excitation light source configured to output an excitation light; an introducing optical element configured to regulate the beam diameter of the excitation light outputted from the excitation light source to a predetermined value; a laser resonator configured to generate, upon introduction of the beam diameter-regulated excitation light thereto by the introducing optical element, a pulsed laser light and output the generated pulsed laser light; an enlarging optical element configured to enlarge the beam diameter of the pulsed laser light outputted from the laser resonator and output the beam diameter-enlarged pulsed laser light; a focusing optical element configured to focus the beam diameter-enlarged pulsed laser light outputted from the enlarging optical element to a predetermined focal point in a combustion chamber of an engine, thereby igniting an air-fuel mixture in the combustion chamber; an optical window member provided on a combustion chamber side of the focusing optical element to protect the focusing optical element; and a substantially cylindrical housing that receives therein the introducing optical element, the laser resonator, the enlarging optical element, the focusing optical element and the optical window member, wherein the housing has a male-threaded portion for fixing the housing and a hexagonal portion for tightening the male-threaded portion, between a combustion chamber-side end of the male-threaded portion and an anti-combustion chamber-side end of the hexagonal portion, there is defined a non-optical element arrangement region in which none of the introducing optical element, the enlarging optical element and the focusing optical element is arranged, and at one of a combustion chamber-side end and an anti-combustion chamber-side end of the non-optical element arrangement region, there is formed a reference surface that extends perpendicular to an axial direction of the housing, and one of the introducing optical element, the enlarging optical element and the focusing optical element is received in the housing in such a manner as to be elastically pressed against the reference surface from outside of the non-optical element arrangement region.