I propose to use as a window the dark core of an optical vortex to examine a weak background signal hidden in the glare of a bright coherent source. Applications such as the detection of an astronomical object, forward-scattered radiation, and incoherent light are described whereby signal enhancements of at least 7 orders of magnitude may be achieved.
© 2001 Optical Society of America
(050.1970) Diffraction and gratings : Diffractive optics
(100.5090) Image processing : Phase-only filters
(120.1880) Instrumentation, measurement, and metrology : Detection
(290.0290) Scattering : Scattering
(350.1260) Other areas of optics : Astronomical optics
Grover A. Swartzlander, Jr., "Peering into darkness with a vortex spatial filter," Opt. Lett. 26, 497-499 (2001)