A light-source optical system includes a wavelength converter on which light of first color is incident, the wavelength converter converting at least a part of the light of first color into light of second color different from the light of first color, a first optical system disposed upstream from the wavelength converter on an optical path of the light of first color, the first optical system including optical elements, a reflection plane disposed downstream from the first optical system on the optical path, and a second optical system disposed downstream from the reflection plane on the optical path. The reflection plane reflects one of the light of first color and the light of second color, and a conditional expression “0<ΔL/D<0.2” is satisfied.

An imaging apparatus includes an imaging optical system that has a light transmission characteristic of transmitting near-infrared light in a near-infrared light wavelength range including 1550 nm, and an imaging sensor that outputs an imaging signal by imaging the near-infrared light transmitted through the imaging optical system, the imaging sensor has sensitivity to heat radiation from a subject, and the imaging signal includes information regarding a heat radiation image by the heat radiation.

A radiational cooling film providing a variable wavelength which determines a solar heat shielding rate according to the internal temperature of a facility and changes a wavelength conversion section of the film exposed to sunlight to radiate a necessary wavelength according to the growth stage of plants, and a wavelength conversion device and system using the same are provided. The radiational cooling film providing a variable wavelength includes a base layer including a first region and a second region on one surface, a heat barrier layer disposed on a part of the other surface of the base layer, the first region being provided with the heat barrier layer, and the second region being not provided with the heat barrier layer, and a wavelength conversion layer including a plurality of wavelength conversion sections separated from each other in each of the first region and the second region.

An electro-optic display having a viewing surface through which a user views the display, a bistable, electrophoretic medium, and at least one electrode arranged to apply an electric field to the electrophoretic medium, the display further comprising at least 10 micromoles per square meter of the viewing surface of at least one compound having an oxidation potential more negative that about 150 mV with respect to a standard hydrogen electrode, as measured at pH 8, where the compound is a sulfite salt or a salt of titanium (III), vanadium (II), iron (II), cobalt (II) or copper (I), a hydroquinone, a catechol, a dihydropyridine or a metallocene.

An electro-optic display having a viewing surface through which a user views the display, a bistable, electrophoretic medium, and at least one electrode arranged to apply an electric field to the electrophoretic medium, the display further comprising at least 10 micromoles per square meter of the viewing surface of at least one compound having an oxidation potential more negative that about 150 mV with respect to a standard hydrogen electrode, as measured at pH 8, where the compound is a sulfite salt or a salt of titanium (III), vanadium (II), iron (II), cobalt (II) or copper (I), a hydroquinone, a catechol, a dihydropyridine or a metallocene.

A projector including a light source, a first prism, a second prism and a digital micro-mirror device (DMD) is provided. The light source emits light. The first prism includes a first surface, a second surface and a third surface which are connected to each other around the perimeter thereof, and the illumination light enters the first prism through the first surface. The second prism has a fourth surface and a fifth surface which are connected to each other, and the fourth surface faces the second surface of the first prism. The DMD faces the third surface. The illumination light sequentially passes through the first surface, is reflected by the second surface, passes through the third surface, and reaches the DMD. The DMD converts the illumination light into image light, and the image light sequentially passes through the third surface, the second surface, the fourth surface and the fifth surface. In the first prism, a first included angle between the first surface and the third surface is more than or equal to 105 degrees.

An optical device is provided. The optical device is capable of varying transmittance, and such optical device can be used for various applications such as eyewear, for example, sunglasses or AR (augmented reality) or VR (virtual reality) eyewear, an outer wall of a building or a sunroof for a vehicle.

A phosphor wheel device includes a motor having a rotation shaft, a phosphor wheel substrate attached to one end side of the rotation shaft, and a balancer fixed to the phosphor wheel substrate. The balancer has at least one opening that is open to an outside of the phosphor wheel device.

An optical microcavity device (10), an alignment structure for an optical device, and a method for aligning an optical device are disclosed. The optical microcavity device (10) comprises: a first optical reflector (20); a second optical reflector (30) opposed to the first optical reflector (20) along an optical axis (40), the first and second optical reflectors (20, 30) being spaced from each other forming an open space therebetween; wherein the first optical reflector (20) comprises a first cavity reflector (22) and a first alignment reflector (24), wherein the second optical reflector (30) comprises a second cavity reflector (32) and a second alignment reflector (34), the second cavity reflector (32) comprising a recess to provide an optical microcavity between the first and second cavity reflectors (20, 30), the optical microcavity having an optical cavity length of at most 50 μm and/or an optical mode volume of 100 μm3 or less; an EM radiation source (50) configured for illuminating the optical microcavity with EM radiation (52) to cause multi-pass interference within the optical microcavity; and an alignment system configured to: illuminate the first and second alignment reflectors (24, 34) of the first and second optical reflectors (20, 30) to generate an optical interference pattern (74); detect the optical interference pattern (74); and determine a relative orientation and/or separation of the first and second optical reflectors (20, 30) based on the detected optical interference pattern (74); the alignment system further comprising an actuator system (100, 102) configured to move the first and second optical reflectors (20, 30) relative to each other to change the relative orientation and/or separation of the first and second optical reflectors (20, 30) based on the determined relative orientation and/or separation. At least one of the first and second alignment reflectors (20, 30) may comprise an alignment structure comprising at least two reflective surface portions having different angular orientations.

Examples include a device including a nanovoided polymer element having a first surface and a second surface, a first plurality of electrodes disposed on the first surface, a second plurality of electrodes disposed on the second surface, and a control circuit configured to apply an electrical potential between one or more of the first plurality of electrodes and one or more of the second plurality of electrodes to induce a physical deformation of the nanovoided polymer element.