Method Liquefaction of Starchcontaining Material

• US 20080278692A1
• Filed: 08/25/2005
• Published: 11/13/2008
• Est. Priority Date: 08/30/2004
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Weekamp, Johannus Wilhelmus, Sanders, Renatus Hendricus Maria
• Granted Patent: US 7,775,670 B2
• Time in Patent Office: Days
• US Class Current: 353/38
• CPC Class Codes: G02B 26/005 based on electrowetting
• CPC Class Codes: G02B 26/06 for controlling the phase of light G02B26/08 takes precedence , measuring optical phase difference G01J9/00
• CPC Class Codes: G02B 27/48 Laser speckle optics
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: G03F 7/70583 Speckle reduction, e.g. coherence control or amplitude/wavefront splitting
• CPC Class Codes: H04N 5/74 Projection arrangements for image reproduction, e.g. using eidophor
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161

Abstract

The present invention relates to a laser projection system (1) having means for reducing the coherence of a generated laser beam (3) in order to reduce the occurrence of annoying speckle artefacts in images produced by the system. Coherence is reduced by letting the laser beam (3) pass through a transparent cell (6) comprising first (A) and second (B) immiscible fluids having different refractive indices. The fluids are displaced in the cell, preferably using an electrowetting technique. The cell (6) may thus be realised as an electrowetting lens, which is driven with a pseudo random driving signal.

Claims

1. A laser projection system, comprising a laser light source (2) for generating a laser beam (3), means (4) for projecting the laser beam (3) onto a surface, and speckle reduction means for reducing speckle artefacts, wherein said speckle reduction means (6, 7) comprises a transparent cell (6), arranged in the path of the laser beam (3), said cell (6) comprising first (A) and second (B) immiscible fluids, having different refractive indices, and control means (7) for controlling the positions of the first (A) and second (B) fluids in the cell (6) in order to vary the optical path length of the laser beam (3) when propagating through the cell (6).

2. A laser projection system according to claim 1, wherein the control means (7) controls the positions of the first (A) and second (B) fluids based on an electrowetting effect.

3. A laser projection system according to claim 2, wherein the speckle reduction means comprises an electrowetting lens.

4. A laser projection system according to claim 3, wherein the electrowetting lens is provided with a pseudo random control signal.

5. A laser projection system according to claim 1, wherein said optical path length varies more than λ

/4 where λ

is the wavelength of the light produced by the light source (2).