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公开(公告)号：BR8606399A
公开(公告)日：1987-10-13
申请号：BR8606399
申请日：1986-12-23
Applicant: IBM
Inventor： FAN BUNSEN , TIBBETTS RAYMOND EUGENE , WILCZYNSKI JANUSZ STANISLAW , WHITMAN DAVID FRANCIS
IPC: H01S3/101 , G02B5/02 , G02B5/08 , G02B27/09 , G03F7/20 , H01L21/027 , H01L21/30 , H01S3/10 , G02F1/29
Abstract: A coherent laser beam (12) having a possibly non-uniform spatial intensity distribution is transformed into an incoherent light beam having a substantially uniform spatial intensity distribution by homogenizing the laser beam with a light tunnel (22) (a transparent light passageway having flat internally reflective side surfaces).When the cross-section of the tunnel is a polygon (as preferred) and the sides of the tunnel are all parallel to the axis of the tunnel (as preferred), the laser light at the exit of the light tunnel (or alternatively at any image plane with respect thereto) will have a substantially uniform intensity distribution and will be incoherent only when the aspect ratio R of the tunnel (length divided by width) equals or exceeds the cotangent of the input beam divergence angle ϑ and whenW min = L coh (R + (1 + R²) 1/2 ) > 2RL coh, where W min is the minimum required width for the light tunnel, and L coh is the effective coherence length of the laser light being homogenized.
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公开(公告)号：DE3778387D1
公开(公告)日：1992-05-27
申请号：DE3778387
申请日：1987-01-16
Applicant: IBM
Inventor： FAN BUNSEN , TIBBETTS RAYMOND EUGENE , WILCZYNSKI JANUSZ STANISLAW , WHITMAN DAVID FRANCIS
Abstract: A coherent laser beam (12) having a possibly non-uniform spatial intensity distribution is transformed into an incoherent light beam having a substantially uniform spatial intensity distribution by homogenizing the laser beam with a light tunnel (22) (a transparent light passageway having flat internally reflective side surfaces).When the cross-section of the tunnel is a polygon (as preferred) and the sides of the tunnel are all parallel to the axis of the tunnel (as preferred), the laser light at the exit of the light tunnel (or alternatively at any image plane with respect thereto) will have a substantially uniform intensity distribution and will be incoherent only when the aspect ratio R of the tunnel (length divided by width) equals or exceeds the cotangent of the input beam divergence angle ϑ and whenW min = L coh (R + (1 + R²) 1/2 ) > 2RL coh, where W min is the minimum required width for the light tunnel, and L coh is the effective coherence length of the laser light being homogenized.
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