Apparatus for focus beam analysis of high power lasers

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.