July 5, 2011

Projection system using high-frequency drive modulation to reduce perceived
speckle

Abstract

An image producing system (1400) delivers images (1414) having reduced speckle
by employing one or more drive circuits (1404, 1405, 1406) that deliver both a
direct current drive signal (205) and an alternating current drive signal (405)
to one or more lasers (1401, 1402, 1403). Specifically, an alternating current
drive circuit (403) is used in conjunction with a direct current drive circuit
(203) to modulate a drive signal. The modulation can be at a frequency of
between 400 MHz and 600 MHz. When lasers, such as the red laser (1401) or the
blue laser (1403) of a multi-laser system are modulated in such a fashion, their
emitted spectral widths (407) greatly expand, thereby reducing speckle in
projected images (1414).

Click here for complete description...