Abstract: A projector comprises: a cooling fan for sucking ambient air through a filter; switching means for switching the operational mode of the cooling fan between a lowland mode and a highland mode; and control means adapted to obtain current fan voltage to determine the normal rpm value for that current fan voltage in reference to a highland voltage-rpm characteristic when the switching means is in the highland mode, obtain current fan rpm, and enables alarming means to issue a filter clogging alarm in the event that the current fan rpm is larger than the normal rpm value plus a predetermined value. Thus, filter clogging can be detected with precision in highlands.

Abstract: An image display device of the present invention comprises projectors, a reflecting mirror, a screen, an image signal processor which performs a distortion correction, and a base for supporting the projectors, the reflecting mirror, and the screen. The projectors, reflecting mirror, and screen are assembled in one to constitute a single moving unit, and the image display device further comprises a lifting device capable of moving the moving unit in a vertical direction with respect to the base.

Abstract: A light engine has a light source front surface that emits non-collimated light. A collection lens collects the non-collimated light and provides incompletely collimated light. A collimating lens receives the incompletely collimated light and provides a collimated image. A non-orthogonal polarizing filter receives the collimated image and passes a polarized portion of the collimated image as a direct component of the polarized light engine image. The non-orthogonal polarizing filter reflects a recycled image back to the front surface. The non-orthogonal shape of the polarizing filter is selected according to the pattern of light on the light source front surface.

Abstract: Light emitted from a lamp enters a color wheel having a region for allowing a predetermined color to pass therethrough, is reflected on a mirror, and enters a DMD. After this, the light is reflected by the DMD and enters a color sensor, which then detects the color of the transmitting light. A projection apparatus automatically synchronizes the control on the rotation of the color wheel and the control on the proceeding direction of the transmitting light by the DMD, based on a color time-division pattern of the transmitting light detected by the color sensor.

Abstract: A light modulator assembly includes first, second, and third light modulators, with first and second dichroic mirrors. The first dichroic mirror is located at an optical pupil of said assembly and is configured to split a beam of light into a first component beam and an intermediate beam. The first dichroic mirror then transmits the first component beam to the first light modulator and reflects the intermediate beam to the second dichroic mirror. The second dichroic mirror is configured to split the intermediate beam into second and third component beams and to direct the second component beam to the second modulator and the third component beam to the third modulator. A third dichroic mirror is configured to receive the output of the first, second, and third modulators and to pass the output from the first, second, and third modulators to display optics.

Abstract: A digital image projector includes a light assembly configured to project light along a light path from at least one laser array light source, the projected light having an overlapping far field illumination in a far field illumination portion of the light path; a temporally varying optical phase shifting device configured to be in the light path; an optical integrator configured to be in the light path; a spatial light modulator located downstream of the temporally varying optical phase shifting device and the optical integrator in the light path, the spatial light modulator configured to be located in the far field illumination portion of the light path; and projection optics located downstream of the spatial light modulator in the light path, the projection optics configured to direct substantially speckle free light from the spatial light modulator toward a display surface.

Abstract: An illuminating optical system propagates a coherent light flux from at least one light source into a predetermined optical path to guide the light flux to a screen. A light bulb forms an image to be displayed on the screen on an illumination area illuminated with the light flux that is guided by the illuminating optical system. A projecting optical unit projects the image that is formed on the illumination area onto the screen in a magnifying manner. The illuminating optical system includes a diffusing unit that diffuses the light flux from the light source near a focusing position of the illuminating optical system.

Abstract: A light emitting apparatus includes: a light emitting device, the light emitting device emitting first and second emitted light; a first optical element; and a second optical element, wherein the first optical element includes a first lens surface on which the first emitted light is incident, a first reflection surface that reflects the light having passed through the first lens surface, and a second lens surface that refracts the light reflected off the first reflection surface, the second optical element includes a third lens surface on which the second emitted light is incident, a second reflection surface that reflects the light having passed through the third lens surface, and a fourth lens surface that refracts the light reflected off the second reflection surface, and the light having exited through the second lens surface and the light having exited through the fourth lens surface travel in the same direction.

Abstract: A rear projection display device (1) includes a screen (10), a projection engine (11) for producing an image light beam, a projection lens (12), and reflectors (13, 14) for projecting the image light beam onto the screen. The projection engine and the projection lens are positioned in rear of the screen within a substantially central portion of the display device. The reflectors are composed of two symmetrically arranged groups of first and second reflectors. The first and second reflectors in each group form a certain angle with each other. The first reflectors divide the image light beam from the projection lens into two image sub-beams, and then reflect them onto the respective second reflectors. The second reflectors reflect the two image sub-beams onto the screen for display a combined single image. By means of the image light beam division and two times of reflection by the reflectors, the depth of the display device is significantly reduced.

Abstract: A projection display device comprises: a light source; liquid crystal panels disposed corresponding to R light, G light and B light; a light guiding optical system for guiding R light, G light and B light among light from the light source to respective corresponding liquid crystal panels; a dichroic prism for synthesizing the R light, G light and B light modulated by the liquid crystal panels; a projection optical system having a curved mirror for enlarging and projecting the light synthesized by the dichroic prism; and a bending mirror. A placement plane for optical members is orthogonal to a projection plane (screen surface), and shorter sides of optical members forming the liquid crystal panels and the light guiding optical system are placed on the placement plane.

Abstract: A lid structure, apparatus and method for displaying graphical information uses beams of coherent light that are emitted in a scanning manner to project the beams of coherent light onto a display surface to form the graphical information on the display surface.

Abstract: A method includes generating a plurality of beams that each illuminate a separate portion of a spatial light modulator. The spatial light modulator has a first dimension of a first length and a second dimension of a second length. Each of the beams spans a portion of the first length of the first dimension and a portion of the second length of the second dimension. The method also includes scrolling the plurality of beams along the second dimension of the spatial light modulator while maintaining at least a first gap between each of the plurality of beams.

Abstract: An optical system (light guiding optical system) for guiding G-light and R-light to liquid crystal panels is protruded in an opposite direction from projection optical system with regard to an optical axis of a light source. A space is created between an optical engine and a wall surface, and air stream for suction fan is thus secured. A distance (H1) between the optical engine and the wall surface can be reduced to, for example, a thickness of an external housing of the projector. Since a unit comprising the light source and a suction fan is retracted in a direction of the projection optical system than a protruded portion of the light guiding optical system, a distance (H2) from an end edge of the optical engine to a projection light emitting position can be reduced.

Abstract: A projector includes: at least one light emitting device having a light emitting element adapted to emit a first outgoing light and a second outgoing light proceeding in a direction different from a direction of the first outgoing light; a first light modulation device adapted to modulate the first outgoing light in accordance with image information; a second light modulation device adapted to modulate the second outgoing light in accordance with image information; and a projection device adapted to project the light modulated by the first light modulation device and the light modulated by the second light modulation device, wherein the light emitting element is a super luminescent diode provided with a stacked structure having an active layer sandwiched between a first cladding layer and a second cladding layer, and the active layer has a first emission surface adapted to emit the first outgoing light and a second emission surface adapted to emit the second outgoing light.

Abstract: An illumination optical system and a projection display apparatus include a beam combining portion and a condensing lens condensing a beam from the beam combining portion. The beam combining portion combines beams from first and second lamp units each including a lamp and a concave mirror, the lamp having a cathode and an anode arranged along an optical axis of the concave mirror. The beam combining portion includes a first reflective section disposed on an optical axis of the first lamp unit and off the optical axis of the second lamp unit and a second reflective section disposed off the optical axis of the first lamp unit. The first and second reflective sections reflect a beam that is emitted from the second lamp unit and that is off an optical axis thereof to combine the beams from the first and second lamp units.

Abstract: There is disclosed an information processor including a housing, a projector attached to the housing, and a screen attached to the housing, wherein the projector projects light onto the screen.

Abstract: System and method for thin projection display systems. An embodiment comprises a light source, an array of light modulators optically coupled to the light source, a lensed mirror optically coupled to the array, and a controller electronically coupled to the array and to the light source. The array produces images on a display plane by modulating light from the light source based on image data and the controller provides light commands to the light source and load image data into the array. The lensed mirror reflects modulated light from the array onto the display plane, the lensed mirror comprising a refractive portion and a reflective portion. The refractive portion of the lensed mirror helps to increase the light bending capability to help reduce the overall thickness of a projection display system.

Abstract: A scanning display device is disclosed. The scanning display device includes: first to M-th scan mirrors (where M is an integer of at least 2), each of which scans a light signal in a first direction; and a scanning unit for scanning the light signal scanned by each of the first to M-th scan mirrors in a second direction, wherein a m-th scan mirror (where 1?m?M?1) scans the light signal in the first direction, and a n-th scan mirror (where 2?n?M) adjacent to the m-th scan mirror scans the light signal scanned by the m-th scan mirror in the first direction.

Abstract: A projector includes a projecting module for projecting a projecting image on a screen panel, an image sensor for capturing an image of an object which is located outside of the projecting module and faces toward the lens module, a light director, and a controlling unit. The projecting module has a lens module and a light source for emitting light transmitting through the lens module. The light director is movable between a first position where the light director is located outside of a light path associated with the lens module, and a second position where the light director is configured for directing light of the object through the lens module to be incident on the image sensor. The controlling unit controls the light director to move between the first and second positions.

Abstract: An optical system is provided. The optical system includes a luminous system which comprises a plurality of light source devices and an image unit; and a projection system which receives light having an image through the luminous system, and enlarges and projects the light, wherein the plurality of light source devices comprise a reflection member which reflects light beam emitted from the light source devices, and are disposed so that the light beam emitted from the light source devices is reflected by the reflection member one time and enters to the image unit.

Abstract: A projection system contains an illumination system having at least a first source of incoherent light capable of generating light in a first wavelength range. The illumination system also includes a body containing a fluorescent material that emits light in a second wavelength range, different from the first wavelength range, when illuminated by light in the first wavelength range. The system further includes at least a second fluorescent material that absorbs light in at least one of the first and second wavelength ranges, and emits light in a third wavelength range. The body has an extraction area, and at least some of the light in either the second or third wavelength ranges is internally reflected within the body to the extraction area. Light from the extraction area illuminates at least one image-forming device. Image light from the image-forming device is projected by a projection lens unit onto a screen.

Abstract: An illumination source includes a number of light emitting diodes (LEDs) operating at a first wavelength. Light from the LEDs illuminates a phosphor material that generates light at a second wavelength. A reflective polarizer transmits light at the second wavelength in a first polarization state and reflects light at the second wavelength in a second polarization state orthogonal to the first polarization state. The light at the second wavelength reflected by the reflective polarizer is directed back towards the phosphor material without an increase in angular range. In some embodiments the LEDs, having a conformal layer of phosphor material, are attached directly to the first surface of a liquid cooled plate. A liquid coolant contacts a second surface of the plate.

Abstract: A multiple-lights-combining illumination device includes multiple light sources, multiple sub-rod integrators that respectively guide light from the multiple light sources, and a main rod integrator that guides light from the multiple sub-rod integrators. Each of the sub-rod integrators has reflection surfaces that are parallel to each other in a longitudinal direction, and has an entrance surface and an exit surface that are parallel or perpendicular to each other at ends thereof, the main rod integrator has reflection surfaces that are parallel to each other in a longitudinal direction, and has an entrance surface and an exit surface that are perpendicular to the reflection surfaces at ends thereof, and each reference optical axis that passes through an optical centroid portion of a light-emitting part of the light sources along a light emission direction is arranged so as to pass through substantially a center of the entrance surface of the respective sub-rod integrator.

Abstract: The present invention provides a light source device for projection display, comprising a light source to be supplemented and a laser light source. The laser emitted from the laser light source and the light emitted from the light source to be supplemented are mixed and then output in a same direction.

Abstract: An illumination apparatus includes a plate-like separation optical element having a dichroic surface and a PBS surface. The dichroic surface reflects green component light and transmits yellow component light. The PBS surface transmits P polarization component light and reflects S polarization component light. The separation optical element combines red component light entering from a certain direction and transmitted through the dichroic surface, with yellow component light entering from a different direction and reflected by the PBS surface, and leads a combined light towards a red liquid crystal panel. The separation optical element combines green component light entering from the certain direction and reflected by the dichroic surface, with yellow component light entering from the different direction and transmitted through the PBS surface, and leads a combined light towards a green liquid crystal panel.

Abstract: A beam alignment system for generating an aligned two-dimensional array of parallel light beams, comprising a beam alignment chamber including a base extending in a length direction and a plurality of reflectors mounted on the base, each having independent yaw and pitch adjustments. The beam alignment system further includes a plurality of arrays of light sources, each generating an array of light beams and being paired with a corresponding reflector, the reflectors being disposed to direct the light beams along the length of the beam alignment chamber forming an aligned two-dimensional array of parallel light beams.

Abstract: An image display apparatus 100 that displays an image using a light modulated according to an image signal includes a projection optical system 90 that includes a projection lens 20, a first mirror 30 that reflects a light from the projection lens 20, and a second mirror 40 that widens an angle of a light from the first mirror 30 by reflecting the light, and projects the light modulated according to the image signal from an optical engine unit 10; a third mirror 50 that reflects a light from the projection optical system 90; and a screen 50 that transmits a light from the third mirror 50. The projection lens 20 and the second mirror 40 are arranged in such a manner that an optical axis of the projection lens 20 substantially matches an optical axis of the second mirror 40, and shift the light from the optical engine unit 10 to a specific side from the optical axis of the projection lens 20.

Abstract: There is provided a projection apparatus using an oblique projection optical system, which generates little reflection loss by providing a linear Fresnel lens at an incident surface in the case where the apparatus is used as a linear system, wherein said linear Fresnel lens makes total reflection of image light, and is capable of obtaining total surface property with good brightness in a region with small incident angle onto a screen, by using a total reflection Fresnel lens and a refraction Fresnel lens in combination. In addition, total surface property with further good brightness can be obtained by using a plurality of projection image display apparatuses in the same projection apparatus.

Abstract: According to one embodiment, a projection system includes a color wheel operable to filter light into a passed component and a reflected component. The projection system also includes a digital micromirror device comprising a plurality of micromirrors each operable to receive the passed component and the reflected component. Each micromirror is selectively positionable to direct, at approximately the same time, the passed component and the reflected component to desired locations. The projection system also includes an optical system operable to direct the passed component and the reflected component from the color wheel to the digital micromirror device at approximately the same time.

Abstract: A laser projector including a green diode pumped microchip laser module projecting a green laser beam, an optical sensor receiving the laser beam, a power control circuit for the green diode pumped microchip laser module receiving a signal from the optical sensor relative to the power output of the laser beam, and control electronics receiving the signal from the optical sensor connected to the power control circuit modulating the power output of the green diode pumped microchip laser module to maintain a substantially constant power output from the green diode pumped microchip laser module.

Abstract: An adjusting mechanism for a rod module adapted to an optical engine is provided. The adjusting mechanism utilizes two wedge-shaped blocks moving in perpendicular directions so as to convert the vertical adjustment of horizontal adjusting component into horizontal adjustment of an LIR module. Therefore, operators may adjust the horizontal and vertical position of the rod module from the same side of the projector, thus increasing the convenience in adjusting the position of the rod module.

Abstract: Provided is an image display apparatus, including: a light modulation element; an illumination optical system which includes at least one light source unit including a plurality of light emitting units two-dimensionally arranged and illuminates the light modulation element; and a projection optical system for enlarging and projecting an image of the light modulation element onto a projection surface, in which: an image of the plurality of light emitting units is imaged at a position corresponding to a stop of the projection optical system; the stop has an aperture shape of rotational asymmetry or of two-fold symmetry; and the plurality of light emitting units have illuminance intensities each independently controlled.

Abstract: A beam alignment chamber extending in a length direction comprising a base having a front edge, and two side edges, first and second opposed side walls connected to the base, and extending along the length of the base, a front wall located at the front edge of the base having an output opening. The beam alignment chamber further comprises a plurality of arrays of light sources disposed to direct light beams through the first or second side walls, and a plurality of reflectors mounted on the base, each having independent yaw and pitch adjustments, each reflector being paired with a corresponding array of light sources, the base-mounted reflectors being disposed to direct the light beams along the length of the beam alignment chamber through the output opening forming an aligned two-dimensional array of parallel light beams.

Abstract: A beam alignment chamber comprising: a base, first and second side walls connected to the base, and a front wall located at the front edge of the base having an output opening. The beam alignment chamber further including a plurality of light sources disposed to direct light beams through the first or second side walls, a plurality of reflectors mounted on the base, each having independent yaw and pitch adjustments, each being disposed to direct the light beams from a corresponding light sources along the length of the beam alignment chamber through the output opening forming an aligned array of parallel light beams, and one or more optical elements positioned in the optical path of the aligned array of light beams disposed to correct the beam divergence with respect to at least one axis.

Abstract: A light source device includes first and second electrodes, an arc tube having a main body section having a discharge space in which the first and second electrodes are disposed with a distance and a sealing section disposed on each of the both ends of the main body section, a primary reflecting mirror disposed on the side of the first electrode, a secondary reflecting mirror disposed on the side of the second electrode, and a current drive device that generates an alternating current for causing the discharge between the first and second electrodes, and power control by controlling the alternating current so that supplying energy in an anodic term of the first electrode becomes smaller than supplying energy in a cathode term.

Abstract: A thin projection type image display device with a low chin height includes a cabinet, a screen, a projection optical system, an optical path changing unit, and a reflecting unit. The screen is disposed on a front side of the cabinet. The projection optical system enlarges and projects an image formed by a display element, and the optical path changing unit is disposed on the bottom of the cabinet to reflect the image enlarged and projected by the projection optical system. The reflection unit is disposed obliquely to the screen and below the screen to reflect the image reflected by the optical path changing unit toward the screen. The projection optical system is disposed in a space above a horizontal plane perpendicular to the screen, behind the front side of the cabinet, and below an optical path of light incident on a bottom of the screen.

Abstract: An entire-visual-field projection device which projects image information relating to an entire-visual-field image onto a spherical screen to provide the entire-visual-field image to a viewer positioned inside the screen. The projection device is provided with the spherical screen, a pair of projectors which project the entire-visual-field image onto the screen and are arranged opposite each other with the center of the screen therebetween, and a double-convex mirror for projection which reflects luminous fluxes from the projectors toward the screen and is disposed in the vicinity of the center of the screen. A projection luminous flux from one of the projectors is emitted to one of the convex surfaces of the mirror, and that from the other projector to the other convex surface of the mirror.

Abstract: First and second lamps 1, 2, first and second ellipsoidal mirrors 3, 4, first and second spherical mirrors 5, 6, and a plane mirror 7 are provided. The first spherical mirror 5 is provided on the same side as the first ellipsoidal mirror 3 with respect to the lamp 1, and the second spherical mirror 6 is provided on the opening side of the second ellipsoidal mirror 4 with respect to the second lamp 2, so that they reflect a respective part of light beams emitted from the first and second lamps toward the first and second ellipsoidal mirrors 3, 4. The first and second ellipsoidal mirrors are arranged such that the optical axes of their reflected light beams intersect with each other, so that they condense respective light beams emitted from the first and second lamps and respective light beams reflected at the first and second spherical mirrors 5 and 6.

Abstract: A multi-reflecting device includes a plurality of double reflecting surfaces formed serially on the rear of a light guide plate having a taper shape. A light incident upon the light guide plate is double-reflected, and progress in a desired direction. The multi-reflecting structure is applied to a backlight unit and a display device so that the backlight unit and the display device can be slimmer economically.

Abstract: There is disclosed a projection device which includes a light source constituted of a reflector and a light source lamp, a projection system including a projection encoder for forming a light image based on an input image signal to project it by use of light from the light source, a micromirror element and a projection lens, a photographing system including a photographing lens for photographing the projected image, a CCD and a process circuit, and a control section detecting a luminance distribution from the photographed image and correcting a luminance distribution of the light image formed by the micromirror element in accordance with the detected luminance distribution.

Abstract: Disclosed herein is a head mounted display including: an eyeglasses frame-like frame to be mounted onto an observer's head; and two image display devices, each of the image display devices including an image generating device, and light guide means which is mounted to the image generating device, which as a whole is located on the side of the center of an observer's face relative to the image generating device, on which beams emitted from the image generating device are incident, through which the beams are guided, and from which the beams are emitted toward an observer's pupil.

Abstract: An illumination apparatus includes first and second light source units. An optical axis converting element has a first surface that reflects a luminous flux emitted from the first light source unit and a second surface that reflects a luminous flux emitted from the second light source unit and is configured to reflect respective luminous fluxes emitted from the respective light source units in substantially one direction. Each of the luminous fluxes entering the optical axis converting element has different dimensions in two directions orthogonal to each other in a plane orthogonal to an emission axis of the each light source unit. The optical axis converting element is arranged such that a cross-sectional shape of the luminous flux entering each optical axis converting element taken along the surface has a short side direction in the same direction as the direction of arrangement of the first and second surfaces.

Abstract: An adjusting device for positioning an integration rod within an optical engine module is provided. The optical engine module includes a casing having four sidewalls defining an optical path. The integration rod is disposed in the optical path. Each sidewall has a screw hole. The adjusting device includes two adjusting screws extending through the screw holes in two adjacent sidewalls of the casing in order to abut against the integration rod, thereby adjusting the position of the integration rod in the optical path and two positioning screws extending through the screw holes in remaining two adjacent sidewalls of the casing to abut against the integration rod for immobilizing the integration rod within the casing.

Abstract: Image projectors with increased light intensity and methods for providing brighter images are provided. Image projectors, described herein, can provide the brightness while still providing any or all of compactness, low power consumption, and long lifetime. To increase brightness, sectional mirrors are used to respectively compress the light from two light sources into a single pupil (e.g. an aperture) of an imaging device. The compression can be accomplished by regions (e.g. sections) of the mirror having different angles with respect to the pupil. Relatively little light may be lost in the compression since minima for a light intensity pattern from a light source may occur between the regions that reflect the light.

Abstract: The present invention relates to an optical projection illumination module that projects highly uniform radiative energy (e.g., visible light, ultraviolet radiation, infrared radiation, etc.) onto a target area. More particularly, the illumination module comprises a radiative energy source (e.g., a LED) configured to provide divergent radiative energy (e.g., a non-uniform illumination) directly to a reflective tunnel (e.g., a total internal reflection tunnel), separated from the radiative energy source by a small gap and optically in contact (e.g., physically coupled) to a front optical element (e.g., collimator lens). The reflective tunnel mixes the divergent radiative energy, and outputs a substantially uniform radiative energy to a front optical element. One or more downstream optical elements image the output of the reflective tunnel directly to the target area (i.e., the object imaged on to the target area is located on an image plane embedded between the reflective tunnel and the front optical element).

Abstract: A projector includes a lighting device having two light source devices each having an ellipsoidal reflector disposed such that the ellipsoidal reflectors face each other, a reflection system that reflects illumination lights emitted from the two light source devices substantially in the same direction, an electro-optic modulating device that modulates the light released from the lighting device according to image information; and a projection system that projects light modulated by the electro-optic modulating device. The two light source devices are disposed such that the respective light source optical axes of the two light source devices are substantially perpendicular to the projection optical axis of the projection system. The reflection system is constructed such that the center axes of the respective illumination lights emitted from the two light source devices and entering a converging lens are inclined toward the illumination optical axis of the lighting device by a predetermined angle.

Abstract: A projecting apparatus for protecting an image onto a screen includes an image module, a first light reflection device and a lens. The image module is for providing a beam of first light. The first light reflection device has a first reflection surface disposed movably relative to the image module for reflecting the first light to form a beam of second light. The lens is for projection the image on the screen according to the second light. Moving the first light reflection device along the beam of first light or second light can adjust the location of the image on the screen in a first direction.

Abstract: A projection display device comprising an illumination module (100; 200; 301) and at least one projection lens (304) for projecting light from said illumination module (301) onto a projection screen (305) is provided. The illumination module (100) comprises at least two lighting units (103, 104), each comprising of a light emitting diode (113, 114) and a collimating funnel (130, 140) arranged in front thereof. The output areas (132, 142) of the two funnels are at least partly overlapping. Hence, light collimation and mixing is possible in the same structure, yielding an etendue conserving illumination module.

Abstract: An illuminator includes: a first light source and a second light source that are disposed substantially symmetrically with respect to an illumination optical axis, wherein each of the first and second light sources includes an arc tube, a first reflector disposed to surround part of the entire space around the optical axis of the arc tube, the first reflector reflecting the light emitted from the arc tube toward an object to be illuminated, and a second reflector disposed on the opposite side of the optical axis of the arc tube to the first reflector, the second reflector reflecting the light emitted from the arc tube toward the first reflector.

Abstract: An image projection system includes a light source for generating a light beam, a reflective housing, and an invisible-light reflector. The reflective housing includes an opening and forms an accommodating space for accommodating the light source so that the light beam can emit from the opening along an optical path. The invisible-light reflector, whose normal is arranged to form an acute angle with the optical path, is installed at a reflecting position intersecting with the optical path outside the opening of the reflective housing. The invisible light of the light beam will be reflected back to the accommodating space by the invisible-light reflector without any destruction caused by the invisible light.