Abstract: Illumination systems are disclosed, which include illumination channels of different colors and at least one image-forming device. Each illumination channel, in turn, includes a bank of light sources, and the image-forming device is disposed to receive illumination from at least one of the illumination channels. At least one of the illumination channels includes an optical element, such as an optical element having optical power or a homogenizing optical element, that is not shared with any other illumination channel and is preferentially constructed or preferentially positioned for the color of its illumination channel.

Abstract: Multi-directional optical elements are disclosed that include a body having a first side having a first curvature, a second side having a second curvature, a third side having a third curvature, and a fourth side having a fourth curvature. The second side is disposed generally opposite the first side along a first direction and a fourth side is disposed generally opposite the third side along a second direction, the second direction being different from the first direction. Also disclosed are optical systems utilizing such multi-directional optical elements.

Abstract: Illumination systems are disclosed that include a light source or a bank of light sources having a non-radially symmetrical aperture having a longer dimension and a shorter dimension, such that the light source or bank of light sources produces illumination with a non-radially symmetrical angular intensity distribution having a larger angular dimension and a smaller angular dimension. The illumination systems include an integrator having an entrance end optically connected to the bank of light sources, an exit end, and a dimension that experiences a larger increase from the entrance end to the exit end. The integrator is disposed so that the dimension experiencing the larger increase is substantially aligned with the larger angular dimension of the illumination produced at the entrance end of the integrator.

Abstract: Methods for producing photographic slides having specified transmission functions are provided in which an image on a computer screen is iteratively adjusted so that a photographic image of the screen when developed has the desired transmission function to within a user-specified criterion. Photographic slides suitable for use in determining a three dimensional configuration of an object, e.g., a patient's tooth, are also disclosed.

Abstract: Three dimensional configurations of a portion of an object (12), such as a patient's tooth, are determined using intensity patterns produced by a projection unit (20) and detected by a sensor unit (22). In some embodiments, the intensity patterns are produced using a set of slides (16A,16B,16C), e.g., a set of photographic slides, while in others they are produced using a transmissive liquid crystal device (60) or a single slide (16) which is moved by a piezoelectric translator (64). Methods and apparatus for reducing the effects of ambient light are also disclosed.

Abstract: A projection display system employs one or more color modifying aperture stops, such as apodizing aperture stops, to provide high contrast, balanced color and high throughput. One projection system includes a reflective liquid crystal-on-silicon light valve positioned with a polarizing beam splitter, such as a wire grid polarizing beam splitter, for each of the primary color component light paths to separately impart image information into each of the primary color components of light. A color combiner receives and combines the primary color components of light with imparted image information to provide light representing a polychromatic display image. At least one aperture stop is positioned along at least one of the primary color component light paths to balance relative intensities of the primary color components of light.

Abstract: A compound polarization beam splitter (33) for use with a reflective, polarization-modulating, imaging device (10), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism (20); (b) an output prism (30), and (c) a polarizer (13), which is located between the two prisms (20,30) and which may be a wire grid polarizer (13a) or a multi-layer reflective polarizer (13b). Polarized illumination light (11) enters the input prism (20) through a first surface (21) and undergoes total internal reflection at a second surface (22) before being reflected from the polarizer (13) and polarization-modulated at the imaging device (10). The polarizer's tilt angle (?) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens (74).

Abstract: High pressure mercury arc lamps are commonly used as the illumination source in many projection systems. Such lamps may be deficient in either output power or spectrum, and so it is desirable to combine the light from the lamp with light from a second light generator. The second light generator may be another mercury lamp or a solid state source, such as one or more light emitting diodes. Different ways of combining light from two light generators are described. The second light source may be an arrangement of a number of red LEDs that supplements the red light produced by the mercury light. A tunnel integrator may be used to homogenize the combined light beam and to reduce the angular separation between the light beams from the two light generators.

Abstract: An LED illumination unit uses a first reflector comprising a reflecting surface formed as a surface of revolution about a first revolution axis. The LED emits light about a first LED axis towards the reflecting surface of the first reflector. The first LED axis is non-parallel to the first revolution axis and the light emitting area of the first LED unit is positioned substantially at a focus of the reflecting surface. The reflector may also have two or more reflecting surfaces for collecting and directing light from two or more respective LEDs.

Abstract: A projection display system employs one or more color modifying aperture stops, such as apodizing aperture stops, to provide high contrast, balanced color and high throughput. One projection system includes a reflective liquid crystal-on-silicon light valve positioned with a polarizing beam splitter, such as a wire grid polarizing beam splitter, for each of the primary color component light paths to separately impart image information into each of the primary color components of light. A color combiner receives and combines the primary color components of light with imparted image information to provide light representing a polychromatic display image. At least one aperture stop is positioned along at least one of the primary color component light paths to balance relative intensities of the primary color components of light.

Abstract: A compound polarization beam splitter (33) for use with a reflective, polarization-modulating, imaging device (10), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism (20); (b) an output prism (30), and (c) a polarizer (13), which is located between the two prisms (20,30) and which may be a wire grid polarizer (13a) or a multi-layer reflective polarizer (13b). Polarized illumination light (11) enters the input prism (20) through a first surface (21) and undergoes total internal reflection at a second surface (22) before being reflected from the polarizer (13) and polarization-modulated at the imaging device (10). The polarizer'stilt angle (&bgr;) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens (74).

Abstract: A tilted polarization splitter (13) for use with a projection lens (15) and a light modulating panel (11) is provided. The polarization splitter has an ultra thin substrate (14) whose thickness is chosen so that the depth of focus of the projection lens in imager space is greater than the astigmatism produced by the splitter at its tilted angle. The polarization splitter can be a wire grid polarizer, polarization coating, or birefringence film carried by or formed on the ultra thin, plane parallel plate substrate.

Abstract: Methods are provided for optimizing the spectrum of a light source used in a projection display system in order to reduce the light loss associated with color splitting/recombination in the system. Projection systems designed in accordance with such methods are also disclosed.

Abstract: A compound polarization beam splitter (33) for use with a reflective, polarization-modulating, imaging device (10), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism (20); (b) an output prism (30), and (c) a polarizer (13), which is located between the two prisms (20,30) and which may be a wire grid polarizer (13a) or a multi-layer reflective polarizer (13b). Polarized illumination light (11) enters the input prism (20) through a first surface (21) and undergoes total internal reflection at a second surface (22) before being reflected from the polarizer (13) and polarization-modulated at the imaging device (10). The polarizer's tilt angle (&bgr;) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens (74).

Abstract: Illumination systems (11) are disclosed which provide scrolling progressive color change on a liquid crystal panel (21), such as a LCoS panel. The systems use transmissive color filters (30, 31, 33) which form an assembly (13) which is rotated about a rotation axis (37). Incident light from a light source (15, 17) passes through the filters and reflects from a reflecting surface (39). As a result of this reflection, the system's optical axis (41, 43) is turned from an orientation substantially perpendicular to the rotation axis to an orientation which does not intersect a filter. Such turning of the optical axis allows colored light to be easily removed from the assembly and avoids problems with color mixing at boundaries between filters as occurs for systems in which light passes through two filters.

Abstract: A compound polarization beam splitter (33) for use with a reflective, polarization-modulating, imaging device (10), e.g., a LCoS device, is provided. The compound PBS has: (a) an input prism (20); (b) an output prism (30), and (c) a polarizer (13), which is located between the two prisms (20,30) and which may be a wire grid polarizer (13a) or a multi-layer reflective polarizer (13b). Polarized illumination light (11) enters the input prism (20) through a first surface (21) and undergoes total internal reflection at a second surface (22) before being reflected from the polarizer (13) and polarization-modulated at the imaging device (10). The polarizer's tilt angle (&bgr;) is less than 45°, which reduces astigmatism and the required back working distance of the system's projection lens (74).

Abstract: An optical assembly (11) is formed by individually positioning a plurality of prisms (15) using mechanical reference surfaces (19) which are associated with the prism's diagonal (13) and are preferably formed by extensions of a first sub-prism (17A) beyond a second sub-prism (17B). The mechanical references surfaces and a first side of the prism engage fixed mechanical references (23) associated with a housing. A locking element (21) engages a second side of the prism and forces the mechanical reference surfaces and the first side of the prism against the fixed mechanical references to achieve accurate positioning of the prism's diagonal (13).

Abstract: A projection display system employs one or more color modifying aperture stops, such as apodizing aperture stops, to provide high contrast, balanced color and high throughput. One projection system includes a reflective liquid crystal-on-silicon light valve positioned with a polarizing beam splitter, such as a wire grid polarizing beam splitter, for each of the primary color component light paths to separately impart image information into each of the primary color components of light. A color combiner receives and combines the primary color components of light with imparted image information to provide light representing a polychromatic display image. At least one aperture stop is positioned along at least one of the primary color component light paths to balance relative intensities of the primary color components of light.

Abstract: A tilted polarization splitter (13) for use with a projection lens (15) and a light modulating panel (11) is provided. The polarization splitter has an ultra thin substrate (14) whose thickness is chosen so that the depth of focus of the projection lens in imager space is greater than the astigmatism produced by the splitter at its tilted angle. The polarization splitter can be a wire grid polarizer, polarization coating, or birefringence film carried by or formed on the ultra thin, plane parallel plate substrate.

Abstract: A tilted polarization splitter (13) for use with a projection lens (15) and a light modulating panel (11) is provided. The polarization splitter has an ultra thin substrate (14) whose thickness is chosen so that the depth of focus of the projection lens in imager space is greater than the astigmatism produced by the splitter at its tilted angle. The polarization splitter can be a wire grid polarizer, polarization coating, or birefringence film carried by or formed on the ultra thin, plane parallel plate substrate.