Abstract: A zoom lens includes an optical path extending between object and image ends, two or more zoom lens groups, an intermediate real image plane in optical path, and all zoom lens groups on an image side or an object side of intermediate real image plane. Zoom lens may include at least one optical path fold in optical path. Field optics in the vicinity of and associated with intermediate real image plane may be in optical path. Zoom lens may include a fixed rear optical group nearest to image end in optical path and a fixed aperture stop in fixed rear optical group wherein aperture stop remains stationary during zooming. Zoom lens may have a magnification with an absolute value greater than 0.4 between intermediate and final real image planes located at image end. Zoom lens may be entirely within a housing of a digital camera or cellphone during its operation.

Abstract: A zoom lens includes an optical path extending between object and image ends, two or more zoom lens groups, an intermediate real image plane in optical path, and all zoom lens groups on an image side or an object side of intermediate real image plane. Zoom lens may include at least one optical path fold in optical path. Field optics in the vicinity of and associated with intermediate real image plane may be in optical path. Zoom lens may include a fixed rear optical group nearest to image end in optical path and a fixed aperture stop in fixed rear optical group wherein aperture stop remains stationary during zooming. Zoom lens may have a magnification with an absolute value greater than 0.4 between intermediate and final real image planes located at image end. Zoom lens may be entirely within a housing of a digital camera or cellphone during its operation.

Abstract: A light is provided having a base unit, an arm extending from the base unit, and a lamp head coupled to the arm. The lamp head includes an LED configured to provide light based on an input drive current, an optical mixing element configured to collect the light produced by the LED and a zoom lens configured to adjust an output size of a spot generated by the light collected in the mixing element. A controller receives DC power from the base unit through the arm. The controller is configured to set the input drive current for the LED to control an output light density of the spot in response to an operator selected input and configured to adjust the output light density of the spot in response to a change in the size of the spot.

Abstract: A light is provided having a base unit, an arm extending from the base unit, and a lamp head coupled to the arm. The lamp head includes an LED configured to provide light based on an input drive current, an optical mixing element configured to collect the light produced by the LED and a zoom lens configured to adjust an output size of a spot generated by the light collected in the mixing element. A controller receives DC power from the base unit through the arm. The controller is configured to set the input drive current for the LED to control an output light density of the spot in response to an operator selected input and configured to adjust the output light density of the spot in response to a change in the size of the spot.

Abstract: Projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a first unit (U1) separated from a positive second unit (U2). The lenses are telecentric on the short conjugate side, have a large field of view in the direction of the long conjugate, have low aberration levels, and include a space between two of the lens elements making up the lens which is sufficient to accept a reflective surface (RS) for folding the lens' optical axis. The second or rear lens unit (U2) includes at least a first color-correcting lens subunit (SU2/CC1) which has a positive-followed-by-negative form and contributes to the correction of the chromatic aberrations of the projection lens, including the correction of lateral color.

Abstract: Projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a first unit (U1) separated from a positive second unit (U2) by a distance sufficient to accept a reflective surface (RS) for folding the lens' optical axis. The lenses are telecentric on the short conjugate side, have a large field of view in the direction of the long conjugate, and have low aberration levels. By using negative lens elements (LU1/N1 and LU1/N2) composed of plastic materials having large positive Q-values at the long conjugate side of the first lens unit (U1), the lenses can achieve low levels of lateral color, including low levels of secondary lateral color, with reduced cost compared to lenses which employ anomalous dispersion glasses in the first lens unit.

Abstract: Projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a negative first unit (U1) separated from a positive second unit (U2) by a reflective surface (RS) which folds the lens' optical axis. The lenses are telecentric on the short conjugate side, have a large field of view in the direction of the long conjugate, and have low aberration levels, including, in particular, low levels of lateral color.

Abstract: Projection lenses for use with pixelized panels (PP) are provided. The projection lenses have a negative first unit (U1) separated from a positive second unit (U2) by a reflective surface (RS) which folds the lens' optical axis. The lenses are telecentric on the short conjugate side, have a large field of view in the direction of the long conjugate, and have low aberration levels, including, in particular, low levels of lateral color.

Abstract: A projection television system (10) is provided which has a CRT (16) and a projection lens system (13) for forming an image on a screen (14). The projection lens system (13) is characterized by a diffractive optical surface (DOS) which provides color correction for the lens system. The diffractive optical surface (DOS) can be formed as part of a diffractive optical element (DOE) or as part of an existing lens element of the lens system. The diffractive optical surface (DOS) is located between the object side (S2) of the lens' first lens unit (U1) and the image side (S11) of the lens' third lens unit (U3). The distance between the diffractive optical surface (DOS) and the lens' aperture stop (AS) is less than 0.1·f0, where f0 is the focal length of the projection lens (13).

Abstract: Projection lenses (13) for use with pixelized panels (PP) are provided. The projection lenses have a negative first unit (U1) which has at least one aspheric surface and a positive second unit (U2) which has three subunits (US1, US2, US3) which have a positive/negative/positive configuration. The lens' aperture stop (AS) is located at the short conjugate end of the lens and is either in the third subunit (US3) or close to that subunit. The lenses are particularly well-suited for use in the manufacture of compact projection systems which employ side illumination of a reflective pixelized panel.

Abstract: Projection lens systems (13) for use in CRT projection televisions (10) are provided. From the screen side, the systems have three lens units (U1, U2, U3), the first two units (U1, U2) forming a retrofocus lens and the third unit (U3) being associated with the CRT during use and serving to correct field curvature. At its screen end, the first lens unit (U1) has a negative element (E1) which has a screen surface (S1) which is concave to the screen. The second lens unit (U2) has two positive subunits (US1, US2), the first subunit (US1) being a color correcting doublet composed of glass and the second subunit having a positive lens element (E2) at its screen end. The projection lens systems are fully color corrected, have f/#'s of 1.0 for an infinite conjugate, have half fields of view of at least 25°, and are economical to manufacture.

Abstract: A projection lens for use with LCD or DMD panels is provided. The lens has three lens units, the first unit having a weak power and at least one aspheric surface, the second unit having a positive power, a high dispersion negative lens element, and a low dispersion positive lens element, and the third unit having a negative power, a positive meniscus lens element and a negative lens element. The projection lens satisfies the following relationships: f0/|f1|<0.6; and BFL/f0>0.3 where (i) f0 is the effective focal length of the combination of the first, second, and third lens units; (ii) f1 is the effective focal length of the first lens unit; and (iii) BFL is the back focal length of the combination of the first, second, and third lens units for an object located at infinity along the long conjugate side of the projection lens.

Abstract: Projection lens for use with pixelized panels are provided which consist of a first lens unit which has a negative power and a second lens unit which has a positive power. The V-values and Q-values of the lens elements of the first and second lens units are selected so that the projection lenses can simultaneously have: (1) a high level of lateral color correction, including correction of secondary lateral color; (2) low distortion; (3) a large field of view in the direction of the image (screen); (4) a telecentric entrance pupil; and (5) a relatively long back focal length.

Abstract: A zoom projection lens for use with pixelized panels is provided. The projection lens has a negative/positive (retrofocus) form, with the positive lens unit (U2) having two positive subunits (U2S1, U2S2). The image (screen) side subunit (U2S1) serves as focus corrector for the lens, i.e., after zooming, this subunit is moved to adjust the focus of the lens. Compared to moving the negative unit (U1), this approach achieves better aberration correction and involves moving less mass through smaller distances.

Abstract: Focusable, color corrected, high performance projection lens systems are provided which include three lens units (U1, U2, U3), the first lens unit being composed of two subunits (U.sub.S1, U.sub.S2). The lens systems can have f/190 's less than 1.0, total fields of as much as 90.degree., low vignetting losses, and MTF values greater than 0.5 at 10 cycles/mm through 0.85 of the full field. By varying the space between the first and second lens units, these performance levels can be maintained as the lens system is focused over a range of conjugates of approximately .+-.7.5% from a center value of about 4 meters. The lens systems can be used in such demanding applications as flight simulators.

Abstract: A lens system for an electronic system has two lenses. The first lens (S1/S2) has a negative power, and the second lens (S4/S5 or S5/S6) has a positive power and is spaced from the first lens (S1/S2) by a distance of at least a quarter of the focal length of the lens system. In one embodiment (FIG. 3), the second lens (S4/S5) is a refractive-diffractive hybrid lens; in which case both the first and the second lenses (S1/S2 and S4/S5) can be composed of acrylic, and can have only spherical and conic surfaces. In other embodiments (FIG. 1, 2, 4), the first lens (S1/S2) has a higher dispersion than the than the second lens (S4/S5 or S5/S6); for example, the first lens (S1/S2) is composed of styrene, and the second lens (S4/S5 or S5/S6) is composed of acrylic. In this case, the first lens (S1/S2) can have a spherical surface and a general aspherical surface, and the second lens (S5/S6) can have conic surfaces (FIG.

Abstract: A projection lens for use with LCD panels is provided. The lens has a first lens unit which has a positive power and a second lens unit which has a negative power. The first lens unit contains at least four lens elements, namely, a positive first lens element, a negative second lens element which is composed of a high dispersion material, a third lens element of weak optical power, and a positive fourth lens element of strong optical power. The projection lens achieves a correction of chromatic aberration on the order of about a quarter of pixel for large LCD panels having pixels on the order of 200 microns.

Abstract: Projection lens having long focal lengths for use with LCD panels are provided. The lenses have a first lens unit which has a positive power and a second lens unit which has a negative power. The first lens unit contains at least three lens elements organized into two subunits, namely, a positive first lens subunit having a positive lens element and a negative lens element and a positive second lens subunit having a positive lens element. The second lens unit contains at least two lens elements, namely, a positive lens element and a negative lens element. The projection lens preferably employs only five lens elements arranged in a positive, negative, positive, positive, negative configuration.

Abstract: A projection lens for use with LCD or DMD panels is provided. The lens has three lens units, the first unit having a negative power and at least one plastic lens element having two aspheric surfaces, a second lens unit having a negative power or a weak positive power and at least one color correcting doublet, and a third lens unit having a positive power and an aspheric surface either on a glass element or on a weak plastic element. The projection lens has a back focal length to focal length ratio of at least 3.0, the ratio being achieved by arranging the first, second, and third lens units so that:D.sub.12 /f.sub.0 >1.0,D.sub.23 /f.sub.0 >0.7,and1.5<(D.sub.12 +D.sub.23 +BFL)/BFL<4.0where: f.sub.0 is the effective focal length of the combination of the first, second, and third lens units; BFL is the back focal length of the combination of the first, second, and third lens units; D.sub.12 is the distance between the first and second lens units; and D.sub.

Abstract: A four element, athermalized projection lens for use in forming an enlarged color image of a LCD panel is disclosed. The powers of the elements from the screen to the LCD are negative/positive/negative/positive and the dispersions are low dispersion/low dispersion/high dispersion/low dispersion. The first three elements are composed of plastic and the last element is composed of glass. The projection lens exhibits a high level of aberration correction over magnifications ranging from about 5.times. to about 12.times.. The four element design comprises the minimum number of elements capable of achieving a relatively long back focal length, athermalization, and lateral color correction of less than about half a pixel.