Laser Speckle Reduction Due to Angular Diversity Introduced by 2D Laser Diode Array

1.2: Speckle suppression method using high‐frequency driving current to semiconductor laser diode

“…All methods fall into two main categories: one is to reduce the coherence of the laser source; the other is the superposition of uncorrelated independent dynamic speckle patterns. Laser coherence can be classified into temporal and spatial coherence, and the temporal coherence of the laser light is usually reduced by using a broadband source or multiple laser sources [8][9][10][11] ; the spatial coherence of the laser is reduced by using a diversity of angles achieved by using decorrelated laser beams from different angles [12][13][14][15][16] . By generating multiple independent uncorrelated dynamic speckle patterns superimposed within the response integration time of the human eye, the perceived speckle is suppressed because of the visual averaging effect [17][18][19][20] .…”