Patent ID: 9181921
Filing Date: 2015-11-10
Classification: F02P,H01T

Abstract:
1. A laser ignition apparatus comprising: an excitation light source configured to output an excitation light; a regulating optical element configured to regulate the excitation light outputted from the excitation light source; a laser resonator configured to generate, upon introduction of the regulated excitation light from the regulating optical element thereinto, 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; and an optical window member arranged on a combustion chamber side of the focusing optical element so as to separate the focusing optical element from the combustion chamber, the optical window member having a combustion chamber-side end surface that faces the combustion chamber and is thus directly exposed to the air-fuel mixture in the combustion chamber, wherein a catoptric-light focal point, at which a catoptric light is to be focused, is positioned on an anti-combustion chamber side of the combustion chamber-side end surface of the optical window member, the catoptric light resulting from reflection of the pulsed laser light outputted from the focusing optical element by a pseudo mirror that is formed by the optical window member when the combustion chamber-side end surface of the optical window member is fouled with contaminants existing in the combustion chamber, and the catoptric-light focal point falls in a region where no solid material forming either the focusing optical element or the optical window member exists.