| 摘要 |
<p>A device is disclosed which, using destructive interference, stops coherent light from lasers but lets through incoherent light. The device comprises four identical gratings (G1, G2, G3, G4). A part of a parallel laser light beam at an entering position (A) is diffracted by the gratings. Another part of the beam passes right through the gratings and interferes with the diffracted beam at an exiting position (B). Regardless of the laser light wavelength, symmetry will make the undiffracted and the diffracted beams meet at the fourth grating (G4) under the same angle as they left the first grating (G1). Thus destructive interference can occur at the fourth grating (G4) across the entire beam width.</p> |
