APPARATUS FOR CONDENSING LIGHT FROM MULTIPLE SOURCES USING BRAGG GRATINGS

• US 20140185286A1
• Filed: 12/19/2013
• Published: 07/03/2014
• Est. Priority Date: 11/11/2005
• Status: Active Grant

• Current Assignee: DigiLens Inc
• Original Assignee: SBG Labs Inc.
• Inventors: POPOVICH, Milan Momcilo, WALDERN, Jonathan David
• Granted Patent: US 9,464,779 B2
• Time in Patent Office: Days
• US Class Current: 362/235
• CPC Class Codes: F21K 9/64 using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: G02B 27/102 for generating a colour image from monochromatic image signal sources
• CPC Class Codes: G02B 27/1086 operating by diffraction only
• CPC Class Codes: G02B 27/42 Diffraction optics , i.e. systems including a diffractive element being designed for providing a diffractive effectG02B27/60 takes precedence
• CPC Class Codes: G02B 5/32 Holograms used as optical elements
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133613 characterized by the sequence of light sources
• CPC Class Codes: G02F 2203/62 Switchable arrangements whereby the element being usually not switchable
• CPC Class Codes: H04N 9/3152 for shaping the light beam beam shaping per se G02B27/09
• CPC Class Codes: H04N 9/3164 using multiple light sources

Abstract

There is provided a colour sequential illumination device comprising in series: first and second light sources; a condenser lens; and a grating device. The grating device comprises at least one Bragg grating. The condenser lens directs light from the first and second sources into the grating device at first and second incidence angles respectively. The grating device diffracts light from the first and second sources into a common direction. Desirably, the Bragg gratings are Electrically Switchable Bragg Gratings. In one embodiment of the invention the light sources are Light Emitting Diodes. Alternatively lasers may be used.

Claims

1-25. -25. (canceled)

26. An illumination device comprising:

a first light source characterized by a first wavelength;

a second light source characterized by said first wavelength;

a collimating lens; and

a first Bragg grating formed by means of a first recording beam incident normal to said grating and a second recording beam incident at an angle to said grating;

wherein said lens collimates and directs light from said second light source towards said grating at a second angle;

wherein said lens collimates and directs light from said second light source towards said grating at a second angle;

wherein said second angle is substantially equal the incidence angle of said second recording beam;

wherein said grating has a maximum acceptance angle for light beams whose average direction corresponds to that of said first recording beam, wherein said maximum acceptance angle is defined by the angle at which the diffraction efficiency of said grating falls to a predetermined value.

wherein said first angle is greater than said maximum acceptance angle,

wherein the normal to said grating defines an illumination axis, and

wherein first grating diffracts said second angle light along said illumination axis.

27. The illumination device of claim 26 further comprising:

a holographic optical element into which superimposed third and fourth Bragg gratings have been recorded;

a third light source emitting light of a second wavelength; and

a fourth light source emitting light of a third wavelength;

wherein said lens collimates and directs said second wavelength light at a third angle with respect to aid holographic optical element, wherein said lens collimates and directs said third wavelength light at a fourth angle with respect to said holographic optical element, and wherein said holographic optical element diffracts said second and third wavelength light along said illumination axis.

28. The apparatus of claim 26 wherein said Bragg grating is an Electrically Switchable Bragg Grating (ESBG).

29. The apparatus of claim 27 wherein said first Bragg grating is a first ESBG and said holographic optical element is a second ESBG.

30. The apparatus of claim 27 further comprising in series a half wave plate;

a third ESBG and a fourth ESBG, wherein said third ESBG is identical to said first ESBG and said fourth ESBG is identical to said second ESBG.

31. The illumination device of claim 27 wherein said first and second light sources are LEDs.

32. The illumination device of claim 28 wherein said third and fourth light sources are LEDs.