Abstract: A light source device includes a laser diode module, a light guide plate selectively optically coupled to the laser diode module, a light projector selectively optically coupled to the laser diode module, and a light path switch module located between the laser diode module and the light guide plate and rotatably switched between a first position and a second position to change a light path of a laser beam emitted from the diode module to a first direction and a second direction different from the first direction. Along the first direction, the laser beam is guided to move toward the light guide plate. Along the second direction, the laser beam is guided to move toward the light projector. The light guide plate has a light incident face which is an arced face recessed from a corner of the light guide plate.

Abstract: A projection-type image display apparatus includes a color separation element including a color separation surface, a light modulation element configured to receive the light divided by the color separation element, a polarizing beam splitter disposed between the color separation element and a projection optical system to separate a light path of a light modulated by the light modulation element according to a polarization direction and guide the resulting light to the projection optical system, and a phase difference plate disposed between the color separation element and the light modulation element. An optic axis of the phase difference plate and the normal of the color separation surface are substantially parallel or perpendicular to each other, in a cross section parallel to a normal of the color separation surface and a normal of the light modulation element.

Abstract: An external polarization conversion device used for a projector includes a first element which converts light from the projector to polarized light in a uniform polarization direction, and a second element which is arranged in a position subsequent to the first element in such a way that there is a space between the first element and the second element and which converts the polarized light from the first element to predetermined polarized light that is different from the polarized light from the first element.

Abstract: Provided is a light source apparatus that includes light emitting tube (21), light pipe (23) which has incident surface (23a) into which light from light emitting tube (21) enters and which has exit surface (23b) from which light that has entered incident surface (23a) is subjected to multiplex reflection to be output, lens (25) into which the light output from exit surface (23b) enters, first parabolic reflection mirror (26) that reflects a part of the light that is output from exit surface (23b) and that does not enter lens (25), and second parabolic reflection mirror (27) which makes the light reflected by first parabolic reflection mirror (26) enter incident surface (23a).

Abstract: A method for projecting a three-dimensional image, that includes providing a first light source and a second light source. A polarizing beam splitter (PBS) is disposed adjacent the first light source and the second light source. An imaging device is adjacent the PBS. A polarization flipping element is disposed adjacent the PBS opposite the imaging device, and a mirror is disposed adjacent the polarization flipping element. A first light is emitted from the first light source. The first light is polarized such that it reflects through the PBS to a polarization flipping element. The first light passes through the polarization flipping element twice such that it will reach the surface of the imaging device. The second light is emitted from the second light source after the first light is emitted. The second light is polarized such that the light passes through the PBS to the imaging device.

Abstract: A projection optical system for use in an image display apparatus having an illumination optical system applying light from a light source, and an image display device receiving the light from the illumination optical system to form a projection image includes a projector lens composed of plural lenses, a first mirror, and a second mirror formed of a concave mirror. The projection optical system is configured to project the projection image onto a projection surface. A projection luminous flux passing through the projector lens to be incident on the first mirror is a luminous flux exhibiting divergence. The projection luminous flux reflected off the second mirror after having reflected off the first mirror is converged once, and the once converged projection luminous flux is projected onto the projection surface. A lens surface of a lens located closest to the first mirror among the lenses of the projector lens is convex.

Abstract: An image projection apparatus includes a light source; a projected image outputting unit having multiple mirrors arranged in a matrix, to which radiating light emitted from the light source while controlling an angle of a light reflection face of each of the mirrors; a control unit controls the angle of light reflection face of the mirrors using the a division half-toning control based on image data of a projected image, and settings of control parameters used for the time division half-toning control; and an image capturing device to capture the projected mage. When the control unit detects a false contour in a projected test pattern image based on image data of the projected test pattern image captured by the image capturing device, the control unit corrects the control parameters for the time division half-toning control based on detection of the false contour.

Abstract: A projective optical system comprises: a lens optical system including lenses; and a transmissive optical element having an anamorphic surface and being provided in an optical path between the lens optical system and a projected surface, wherein the transmissive optical element has a curvature with respect to a direction corresponding to a long side of a display screen of the image display element, and on a cross-sectional surface being perpendicular to the long side of the display screen, and with respect to light being emitted from the lens optical system and being incident to the transmissive optical element, a light intensity of a first light flux being incident to the transmissive optical element at a first incident angle is lower than a light intensity of a second light flux being incident to the transmissive optical element at a second incident angle being larger than the first incident angle.

Abstract: An illuminator includes: a light source section including a laser light source; an optical element through which a laser beam from the laser light source passes; a driving section oscillating the optical element; and a control section controlling, in a driving operation performed by the driving section, the driving operation to allow an oscillating amplitude value of the optical element in a startup period of the optical element to be equal to or less than the oscillating amplitude value of a steady-state operation period of the optical element that is subsequent to the startup period.

Abstract: A light emitting unit array including a plurality of micro-light emitting diodes (?-LEDs) is provided. The micro-light emitting diodes are arranged in an array on a substrate, and each of the micro-light emitting diodes includes a reflection layer, a light emitting structure, and a light collimation structure. The light emitting structure is disposed on the reflection layer, and includes a first type doped semiconductor layer, an active layer, and a second type doped semiconductor layer that are stacked sequentially. At least a portion of the first type doped semiconductor layer, the active layer, and the second type doped semiconductor layer are sandwiched between the reflection layer and the light collimation structure.

Abstract: A safety protection method for a laser projection apparatus is provided. The laser scanning apparatus includes a laser source, a laser source driver, a scanning mirror, and a light-outputting port. The laser source driver is configured to drive the laser source to emit a laser beam. The safety protection method includes the following steps. Firstly, after the laser projection apparatus is powered on, an optical path of the laser beam is adjusted, so that the laser beam is not ejected out from the light-outputting port. Then, the laser source driver is disabled. Then, a judging step is performed to judge whether an intensity of the laser beam is higher than a threshold level. If the intensity of the laser beam is higher than the threshold level, the laser source is turned off.

Abstract: A system for on-product projection and display of electronic content. The system includes a projector for projecting electronic content, a mirror film stack having a reflective surface facing the projector, and a product having an exterior surface facing the reflective surface of the mirror film stack. A graphic is located on a surface of the mirror film stack opposite the reflective surface. The electronic content from the projector is projected onto the exterior surface of the product via the reflective surface of the mirror film stack. The graphic can be located on a display window and hide the mirror from a viewer without completely blocking a view of the projected electronic content. The product can include a removable projection screen for displaying the electronic content, and the projection screen can include a removable label on its non-viewer side to advertise or promote the product.

Abstract: Inflatable, flexible, collapsible, linear solar concentrator and heliostat designs, made primarily of flexible and elastic sheets enclosing and separating air-tight chambers which are elongated along and parallel to a main axis, with the chambers pressurized to different pressures form a structure and control the focus and rotation of a mirror.

Abstract: The invention provides a light uniform device and a digital light processing (DLP) projection system applying the said light uniform device. The light uniform device comprises a light incident surface, a light emergent surface and a light uniform portion defined therebetween. The light incident surface and the light emergent surface have a first contour and a second contour, respectively. And a first projection image of the second contour that is projected onto a projection plane forms a rotational angle about a longitudinal axial direction corresponding to a second projection image of the first contour projected onto the projection plane. Thereby, the light sources may simply be disposed in the projection system to provide uniform light beams that entirely cover the DMD (digital micromirror device) after being uniformed by the light uniform device. Neither of the light sources need to be inclined following with the DMD, nor is additional relay lens needed in imaging.

Abstract: Provided is an optical apparatus including a polarization separation element for separating an incident light beam into a first polarization component and a second polarization component and outputting the first polarization component and the second polarization component, a polarization conversion unit including a waveplate for converting one of the first polarization component and the second polarization component into the other polarization component, the waveplate being held to a holding metal plate, and a housing for holding the polarization separation element and the polarization conversion unit.

Abstract: A device projecting images by micro electro-mechanical system (MEMS) technology mirrors includes a base, a first substrate, a first reflective mirror, a second substrate, and a second reflective mirror. The first substrate and the second substrate are adjacently positioned on the base. The first reflective mirror is formed on the first substrate by a micro electro-mechanical system (MEMS) technology and configured for receiving a light beam and rotating in two directions under control of the MEMS for reflect the received light in two directions. The second reflective mirror is formed on the rotatable second substrate to receive the image and be rotated, thus further adjusting the range of the projected images.

Abstract: An illuminating device for emitting light onto a light modulating element that forms an image in accordance with a modulation signal and irradiates a target to be illuminated with light, the illuminating device includes a substrate on which equal to or more than two phosphors that emit light with exciting light are formed in a band-like form along a predetermined direction, equal to or more than two light collecting units that are arranged for the respective equal to or more than two phosphors, and collect light components emitted from the respective equal to or more than two phosphors, and a driving unit that drives the substrate in the predetermined direction.

Abstract: An optical system includes: a reflective imaging element; and a liquid crystal display panel disposed on a light-incident side of the reflective imaging element, the liquid crystal display panel having a display surface which is inclined with an angle of no less than 45° and no more than 75° relative to a plane defined by the reflective imaging element, a viewing angle dependence of a contrast ratio of the liquid crystal display panel taking a central value in a direction inclined by 10° or more in a direction of tilt of the display surface from a normal of the display surface, and causes an image displayed on the display surface of the liquid crystal display panel to form an image at a position of planar symmetry with respect to the reflective imaging element as a plane of symmetry.

Abstract: A disclosed projection optical system projects images on a surface to be projected on. The projection optical system includes a first optical system including at least one refraction optical system and having positive power as a whole, a folding mirror, and a second optical system including at least one reflection surface having power and having positive power as a whole. Further the folding mirror folds a light path from the first optical system to the second optical system, and in a plane including an optical axis of the first optical system and a normal line of the surface to be projected on, the following conditional expressions (1) through (3) are satisfied (1) 0.43?d1, (2) 0.43?d2, and (3) 0.7?d2/d1?2.0.

Abstract: A method of detecting a scanning angle range of a laser beam of a laser projector is provided. First, a photo sensor is disposed between first and second positions on a projection mirror. Then, a laser beam emitted from the laser projector scans back and forth between the first and second positions, so that the photo sensor receives the laser beam sequentially at first and second scanning time points to generate first and second sensing signals, respectively. If an actual time interval between the first and second sensing signals conforms to an expected time interval, an actual scanning angle range of the laser beam is determined as normal. If the actual time interval does not conform to the expected time interval, the actual scanning angle range of the laser beam is determined as abnormal and the laser projector stops emitting the laser beam. A laser projector is also provided.

Abstract: Embodiments of the present invention provide apparatuses and systems for providing illumination for projectors. One or more beam combiners are used to combine multiple light beams to provide a combined light beam toward to a pupil of an imaging device in a projector. Solid state light sources, such as diode lasers and light-emitting diodes (LEDs), may be used as light sources at relatively low cost and low power, and with long lifetime. In one embodiment, an optical beam combiner comprises a first reflective surface, a second reflective surface, and a transparent region disposed between the first reflector surface and the second reflective surface. In another embodiment, an optical device comprising an array of optical beam combiners is provided. In a further embodiment, light sources comprising a plurality of light-emitting devices mounted on curved surfaces are utilized in conjunction with an optical beam combiner to provide illumination for a projector.

Abstract: An image projection apparatus is provided, which includes an illumination unit which generates illumination light, a first prism which receives the illumination light from the illumination unit and performs total reflection of the illumination light, a reflection mirror which receives the illumination light from the first prism and reflects the illumination light, an image forming unit which forms an image from the illumination light that is reflected from the reflection mirror, and a second prism which performs total reflection of the image that is formed by the image forming unit toward a screen.

Abstract: An image projection apparatus includes a light source; a projected image outputting unit having multiple mirrors arranged in a matrix, to which radiating light emitted from the light source while controlling an angle of a light reflection face of each of the mirrors; a control unit controls the angle of light reflection face of the mirrors using the a division half-toning control based on image data of a projected image, and settings of control parameters used for the time division half-toning control; and an image capturing device to capture the projected mage. When the control unit detects a false contour in a projected test pattern image based on image data of the projected test pattern image captured by the image capturing device, the control unit corrects the control parameters for the time division half-toning control based on detection of the false contour.

Abstract: There is provided a projection optical system capable of projecting an image formed on an image forming unit on a projection plane, which has an extremely short projection distance and a small size.

Abstract: An illumination system and a projection device comprising the same are provided. The projection device comprises an imaging system and the illumination system. The illumination system comprises a first light source, a dichroic element, at least one condensing element, a rotary wheel and a light integrating element. The first light source provides a first wave band light, and the rotary wheel has at least one wave band transforming area and a reflecting area. After passing through the dichroic element and the at least one condensing element, the first wave band light will be focused onto the at least one wave band transforming area to be transformed into a second wave band light or be focused onto the reflecting area that will be reflected. The second wave band light and the reflected first wave band light will be focused on the light integrating element by the at least one condensing element.

Abstract: In a light source device, in each division of an image frame, two or more of the color lights X, Y and Z (e.g., red, green and blue) can be projected simultaneously. Each of the color lights X, Y and Z is divided into two in terms of time so that synthesized light of one group of division color lights enters a first spatial modulation element. Synthesized light of another group of division color lights enters a second spatial modulation element, whereby gradation of each color light in each of the first and second spatial modulation elements is controlled.

Abstract: This projector includes a laser beam generation portion outputting a laser beam, an image projection portion, including a scanning portion scanning the laser beam, projecting an image on a projection area, an image correction portion correcting distortion of the projected image on the basis of projection condition information, a photoreceiving portion receiving the laser beam reflected by a detection object, and a position acquisition portion acquiring the position of the detection object on the basis of photoreceiving information of the laser beam received by the photoreceiving portion and the projection condition information employed by the image correction portion for correcting the image.

Abstract: A display system that includes a projector light bulb. The system includes a light fixture with a conventional light bulb socket. A projector light bulb is provided with a socket adapter for mating electrically with the light bulb socket. A projector such as a pico projector is fit into the socket adapter or to mate with this adapter to be powered by the light bulb socket via the adapter. In lamp-type implementations, the projector is used to project onto a lamp shade-shaped rear projection screen or through a translucent shade and also upon surfaces of the ceiling or objects above the projector light bulb. A light conditioning or directing assembly may be provided that directs a portion of the projected light onto the projection screen (or shade) and another portion up onto the ceiling so as to concurrently focus on two or more surfaces at two or more focal distances.

Abstract: A system and a method for time-multiplexed autostereoscopic display are disclosed, wherein the system includes a projector, an optical relaying device and a slit array. The projector can project a plurality of rays of different directions in different time sequences respectively. The optical relaying device is optically coupled with the projector for relaying the rays. The slit array is optically coupled with the optical relaying device for being illuminated by the rays. The slit array further has a plurality of regions which are illuminated by the rays respectively; and each of the regions has a plurality of slits which are turned on sequentially for a part of the rays to pass therethrough. Therefore, the display system can reduce the light loss of the rays each time when a 3D virtual image is formed.

Abstract: A projection display satisfies formulas {(4FR?)/(W?TphR)}?0.015 and W??0.5, where: F is an F-number of a projection lens; W? is a diagonal size (inch number) of a light modulation element; ph is a pixel count in one side direction of the light modulation element; T is a throw ratio of the projection display (=a projection distance s/a distance L in the one side direction of a projected image on a projection plane); R is a radius of an exit pupil of the projection lens; I is an integrated light quantity obtained by, in a light quantity distribution in the exit pupil, radially integrating the light quantity up to the radius R; and I?(=I/2) is an integrated light quantity obtained by, in the light quantity distribution in the exit pupil, radially integrating the light quantity up to a predetermined radius R? about barycenter of the light quantity distribution.

Abstract: A floating image display device includes an object, and a light reflecting optical member for reflecting displayed light from the object to a viewer. The light reflecting optical member comprises a structure in which micro mirror units each having first and second light reflecting sides are arranged in matrix. The light reflecting optical member reflects the displayed light by the first and second light reflecting sides at two times to form a mirror image. The light reflecting optical member comprises a first assembly and a second assembly. Each of the first and second assemblies is constructed by arranging a plurality of longitudinal members each having one light reflecting side such that all of the light reflecting sides are oriented in a same direction. The first assembly and the second assembly are laminated onto each other with the light reflecting sides of the first assembly and the light reflecting surfaces of the second assembly intersecting with each other.

Abstract: Optical MEMS scanning micro-mirror comprising: —a movable scanning micro-mirror (101) pivotally connected to a MEMS body (102) substantially surrounding the lateral sides of the micro-mirror; —an transparent prism (500, 600) substantially covering the reflection side of the micro-mirror; —wherein said prism has its outer face non-parallel to the micro-mirror neutral plane N-N, thereby providing a dual anti-speckle and anti-reflection effect, namely against parasitic light. The invention also provides the corresponding micro-projection system and method for reducing speckle.

Abstract: A scanning laser projector includes a scanning mirror that moves in a sinusoidal motion on at least one axis. Pixels are displayed by modulating a laser beam that is reflected by the scanning mirror. Pixels are generated using light pulses of different duty cycles based on the position and/or angular velocity of the laser beam.

Abstract: A mirror actuator system is provided for aligning images projected onto a curved screen by dual projectors. According to a preferred embodiment, a unique screw mechanism is provided for selectively slightly warping the mirror. The screw mechanism includes a load spreader in contact with the mirror, having a groove for receiving an screw actuator for applying positive or negative pressure to the load spreader and thereby to a local area (i.e. zone) of the mirror. The actuator system of the present invention provides low cost static pressure adjustment to the mirror for maintaining the focus quality while locally modifying the geometric ‘aim’ of the mirror. The groove in the load spreader provides tolerance to prevent thermal coefficient of expansion (TCE) distortion.

Abstract: A projection optical system comprises an image forming unit that forms an image; a refractive optical system including a plurality of lenses that enlarges and projects the image on a screen; and a reflecting surface, wherein an intermediate image is formed between the refractive optical system and the reflecting surface, and the projection optical system satisfies conditions of “0.6<D/Did<0.8” and “2.5<Did/F<6”, where “Did” represents a maximum paraxial image height of the intermediate image in a focusing state in which a projection image is maximum, “D” represents a maximum value of a distance between an optical axis and an intersection of a paraxial image surface and a light beam passing center of an aperture stop of the refractive optical system, and “F” represents a focal length of the refractive optical system in a focusing state in which the projection image is maximum.

Abstract: A light source unit includes a first reflector having a reflection face; a second reflector having a reflection face; a plurality of light sources; and a light condensing optical system disposed between the first reflector and the second reflector. Light beams emitted from the plurality of light sources are reflected at a first reflection position on the reflection face of the first reflector, and then reflected at a second reflection position on the reflection face of the second reflector. The second reflection position is close to an optical axis of the light condensing optical system compared to the first reflection position. The light condensing optical system is configured such that the light beam passes through the light condensing optical system at least two times when the light beams reflect between the first reflector and the second reflector.

Abstract: A red image is displayed on liquid crystal panel (111) by lighting red light source (101) for a predetermined period. A green image is displayed on liquid crystal panel (112) by lighting green light source (102) for the predetermined period. A green image is displayed on liquid crystal panel (113) by lighting green light source (103) for the first of first and second periods provided by dividing the predetermined period with a predetermined ratio. A blue image is displayed on liquid crystal panel (113) by lighting blue light source (104) for the second period.

Abstract: An optical unit includes a light source that emits light to be projected onto a screen, one or a plurality of optical elements that controls a spread of a beam of light from the light source to the screen, a combining element that combines the light emitted from the light source, and a scanning element. The light source outputs an optical beam that will generate an elliptically shaped beam spot on the screen, the beam spot having a major axis substantially perpendicular to a scanning direction, and the light source is driven with pulse width modulation (PWM) so that one driven pulse corresponds to one beam spot on the screen.

Abstract: A projection display device includes: a light source unit including light sources emitting light in a plurality of colors, condenser lenses and a color combining optical element; a total reflection prism that totally reflects a combined light flux from the color combining optical element so as to be guided to an image forming unit; and a projection lens. At least one of; an entry surface of the color combining optical element through which substantially parallel light fluxes from the condenser lenses enter, an exit surface of the color combining optical element through which the combined light flux exists, and an entry surface of the total reflection prism through which the combined light flux enters, is formed as a free curved surface where a shape of a section of the combined light flux is altered so as to be matched with a shape of an outline of the display area.

Abstract: An optical polarization state modulator assembly for use in a stereoscopic three-dimensional image projection system includes a spatial light modulator, a light source emitting multiple wavelength components of light for incidence on the spatial light modulator, and a projection lens. A polarization converter system cooperates with the spatial light modulator to produce in alternating sequence polarized light carrying first and second perspective view images of a scene in different ones of first and second subframes. A polarization modulator, in response to first and second drive signals, imparts to, respectively, the image-carrying polarized light a first output polarization state during the first subframe and to the image-carrying polarized light a second output polarization state during the second subframe. The image-carrying polarized light in the first and second output polarization states propagates through the projection lens for transmission to an observer.

Abstract: An electronic device having a 3-D image projection mechanism is provided. The electronic device comprises a display panel, a processing module, a projection screen and at least two micro projectors. The display panel is formed on a main body of the electronic device to display a 2-D display frame. The processing module determines whether a 3-D display request is received and generates a 3-D display command when the 3-D display request is received. The projection screen is formed according to the 3-D display command and is substantially vertical to the display panel, in which a light refractive rate of the projection screen is different from that of the air around the projection screen. The micro projectors are disposed in a circumference of the display panel and project image on the projection screen according to the 3-D display command such that a 3-D display frame is formed thereon.

Abstract: A projection apparatus with locking structure includes an apparatus case including a main casing, a lid and at least one locking structure at the main casing and the lid, a light source, a light valve and a lens. The structure includes a slot having two opposite ends at the casing, at-least one elastic arm in the slot and at-least one positioning pillar at the lid. When the lid covers the main casing and the pillar extends into the first end, by rotating the lid relatively to the main casing, the pillar moves along the slot to the second end; when the pillar is at the second end, the elastic arm limits the pillar at the second end. The light source is for providing an illumination beam. The light valve and lens are for respectively converting the illumination beam into an image beam and the image beam into a projection beam.

Abstract: A portable image projection device has a housing with first and second members pivotable between device folded and unfolded positions. First lens optics mounted within the first member are configured for projecting light modulated by a spatial light modulator along an optical axis through a first aperture with a first throw ratio with the device in the folded position. A second lens optics element movably mounted within the first member is configured for selective movement between positions of non-intersection and intersection with the optical axis. The second lens optics element is configured for cooperating with at least part of the first lens optics for projecting the light modulated by the spatial light modulator along the optical axis through a second aperture with a second throw ratio less than the first throw ratio with the device in the unfolded position.

Abstract: The polarization beam splitting element is configured to reflect or transmit an entering beam according to its polarization direction. The element includes, in order from a beam entrance side, a base member having a light transmissive property, a first one-dimensional grating structure formed of a dielectric material and having, in a first direction, a first grating period smaller than a wavelength of the entering beam, and a second one-dimensional grating structure formed of a metal and having, in a second direction orthogonal to the first direction, a second grating period smaller than the wavelength of the entering beam.

Abstract: An image projection method includes: reflecting, by a concave mirror, light having transmitted through one or more lenses after forming an intermediate-focused image of the light; and projecting an image onto a projection plane through reflecting the light reflected by the concave mirror by a plane mirror that has an aspect ratio of 1.9 or more.

Abstract: A light emitting device includes a laminated body having an active layer, a first cladding layer, and a second cladding layer, the active layer constitutes an optical waveguide, the optical waveguide includes a first portion connecting a first exit section and a first reflecting section to each other, a second portion connecting the first reflecting section and a second reflecting section to each other, and a third portion connecting the second reflecting section and a second exit section to each other, and a current density in the first portion and a current density in the third portion are higher than a current density in the second portion.

Abstract: A projection unit projects the optical image formed by the optical image formation unit toward a projection target. A temperature detection unit detects a temperature of each type of the semiconductor light emitting elements during light emission. A measurement unit measures an intensity of light from each type of the semiconductor light emitting elements during light emission. A light emission control unit (a) corrects a measurement result from the measurement unit using a detection result from the temperature detection unit and (b) controls the light emission intensity for each of the semiconductor light emitting elements based on the corrected measurement result.

Abstract: A light emitting device includes: an active layer; and a first cladding layer and a second cladding layer that sandwich the active layer, wherein the active layer forms an optical waveguide that guides light, a traveling direction of the light guided in the optical waveguide changes at a first reflection part provided on a first side surface of the active layer, and the first reflection part is located outside of a region in which the first cladding layer and the second cladding layer are provided in a plan view.

Abstract: A projection optical system includes first and second optical systems. The first optical system includes a transmissive-refractive element and the second optical system includes a reflective-refractive element. An image formed by a spatial light modulator is projected by the projection optical system on a projection surface. A light beam that travels along an optical path that leads from the second optical system to the projection surface in an optical path between a center of the image formed by the spatial light modulator and the projection surface is projected at an angle with respect to a normal to the projection surface. An optical axis of the first optical system is folded to a folded position by an optical path deflecting unit in an area of the first optical system where the light beam entering the optical path deflecting unit is a converging light beam or a substantially parallel light beam.

Abstract: In a projection optical system for use in an image projection apparatus illuminating an image display panel forming an image in accordance with a modulating signal with illumination light from a light source, the projection optical system includes first and second optical systems arranged along an optical path defining an upstream-downstream direction in the order described from upstream to downstream on the downstream side of the image display panel. The first optical system includes at least one dioptric system and has positive power. The second optical system includes at least one reflecting surface having power and has positive power. The image formed by the image display panel is formed as an intermediate image in the optical path, and the intermediate image is magnified and projected.