Apparatus for focus beam analysis of high power lasers

An apparatus for focus beam analysis of a high power laser, comprising:

• a dove prism positioned between a laser beam light source and a process focusing lens;
• said dove prism having an entry surface and an exit surface;
• said process focusing lens having an entry surface and an exit surface;
• a first pixelated detector positioned to receive light reflected from said dove prism entry surface, said first pixelated detector adapted to measure a raw laser beam diameter;
• a second pixelated detector positioned to receive light from said dove prism exit surface;
• a majority of said laser beam light passing through said dove prism, said process focusing lens, and impinging upon a workpiece;
• said laser beam light reflected from said exit surface of said process focusing lens being reflected back towards said laser beam source;
• said back-reflected light being focused at about one-half the focal length of said process focusing lens because said light travels through said process focusing lens twice and is then reflected to said second pixelated detector via said exit surface of said dove prism;
• whereby light reflected from said exit surface of said process focusing lens is focused on said second pixelated detector, thereby enabling early indication of a dirty or contaminated process focusing lens and avoiding the need for periodic examination of said process focusing lens;
• said dove prism permitting on-axis processing where a slight angle to prevent back-reflections to said laser beam source is not desired.

An apparatus for focus beam analysis of a high power laser, comprising:

• a laser beam light source having an optical axis;
• a pair of matched Risley prisms, each of which has a first and second surface, disposed in light-collecting relation to said laser beam light;
• a workpiece;
• a process focusing lens disposed between said pair of matched Risley prisms and said workpiece, said process focusing lens having a first and second surface;
• said pair of matched Risley prisms including a first prism and a second prism, said first prism being closer to said source of laser beam light than said second prism;
• said first and second prisms arranged so that their respective angles are one hundred eighty degrees (180°) out of phase so that there is no angular deviation from said optical axis and so that light reflected from respective first surfaces of said first and second prisms does not interfere with light reflected from respective second surfaces of said first and second prisms;
• a first pixelated detector disposed radially outwardly of said first surface of said first prism in light-receiving relation thereto;
• back-reflected light from said first surface of said first prism being focused on said first pixelated detector and enabling a raw laser beam to be reflected to said pixelated detector;
• and
• a second pixelated detector disposed radially outwardly of said second surface of said second prism in light-receiving relation thereto;
• whereby light reflected from said exit surface of said process focusing lens is focused on said second pixelated detector, thereby enabling early indication of a dirty or contaminated process focusing lens and avoiding the need for periodic examination of said process focusing lens.

An apparatus for focus beam analysis of a high power laser having an optical axis, comprising:

• a dove lens positioned between a laser beam light source and a process focusing lens;
• said dove lens having an entry surface and an exit surface;
• said process focusing lens having an entry surface and an exit surface;
• a first pixelated detector disposed normal to said optical axis in alignment with said entry surface of said dove prism;
• a second pixelated detector disposed normal to said optical axis in alignment with said exit surface of said dove prism;
• a negative power lens positioned between said exit surface and said second pixelated detector;
• said negative power lens changing the focus of light directed to said second pixelated detector so that said negative power lens has a focal length equivalent to said focus processing lens;
• whereby light back-reflecting from said second surface of said process focusing lens travels backwards through said process focusing lens, its effective focal length decreasing by nearly a factor of two;
• whereby said negative power lens changes the effective focal length back to the original focal length so that said second pixelated detector measures the focus of the apparatus at the same effective focal length;
• and
• whereby light reflected from said exit surface of said process focusing lens is focused on said second pixelated detector, thereby enabling early indication of a dirty or contaminated process focusing lens and avoiding the need for periodic examination of said process focusing lens.