Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have a pixel array that produces light associated with images. The display system may also have a linear polarizer through which light from the pixel array passes and a quarter wave plate through which the light passes after passing through the quarter wave plate. The optical system may be a catadioptric optical system having one or more lens elements. The lens elements may include a plano-convex lens and a plano-concave lens. A partially reflective mirror may be formed on a convex surface of the plano-convex lens. A reflective polarizer may be formed on the planar surface of the plano-convex lens or the concave surface of the plano-concave lens. An additional quarter wave plate may be located between the reflective polarizer and the partially reflective mirror.

Abstract: Various embodiments include methods of reducing false-particle counts in a water-based condensation particle counter (CPC). One embodiment of a method includes delivering water into one or more wicks, sensing an excess volume of water delivered to the wicks, collecting the excess volume of water into a collection reservoir, and draining the excess volume of water from the collection reservoir. Other methods and apparatuses are disclosed.

Abstract: A head-mounted display may include a display system and an optical system in a housing. The display system may have a pixel array that produces light associated with images. The display system may also have a linear polarizer through which light from the pixel array passes and a quarter wave plate through which the light passes after passing through the quarter wave plate. The optical system may be a catadioptric optical system having one or more lens elements. The lens elements may include a plano-convex lens and a plano-concave lens. A partially reflective mirror may be formed on a convex surface of the plano-convex lens. A reflective polarizer may be formed on the planar surface of the plano-convex lens or the concave surface of the plano-concave lens. An additional quarter wave plate may be located between the reflective polarizer and the partially reflective mirror.

Abstract: Multi-functional piezo-actuated flow control systems and methods for use in gas exchange analysis systems such as photosynthesis measurement systems. A fluid valve assembly module includes a housing structure including a plurality of ports and a plurality of fluid passageways interconnecting the ports, and a plurality of piezo-actuated valves in fluid communication with the fluid passageways, each valve including a piezo element that controls flow along a passageway, wherein the passageways and valves are arranged within the housing structure so as to define a fluid control module, which includes a flow swapping component, a flow splitting component and a flow pressurization component.

Abstract: Systems and methods for determining gas velocity based on phase differences of signals from two or more interaction paths in a gas analyzer system. A laser source, which can provide access to an absorption gas line, is expanded, or is split into two or more beams. These beams can be used to create two (or more) parallel sampling paths separated by a known distance. Gas travelling in the plane of the two beams of light will pass through the optical paths at two (or more) different times creating very similar signals that will be out of phase with each other. The amount of phase difference will be inversely proportional to the velocity of the gas.

Abstract: Systems and methods for determining gas velocity based on phase differences of signals from two or more interaction paths in a gas analyzer system. A laser source, which can provide access to an absorption gas line, is expanded, or is split into two or more beams. These beams can be used to create two (or more) parallel sampling paths separated by a known distance. Gas travelling in the plane of the two beams of light will pass through the optical paths at two (or more) different times creating very similar signals that will be out of phase with each other. The amount of phase difference will be inversely proportional to the velocity of the gas.

Abstract: A method for metallizing a vertically aligned carbon nanotube array includes coupling a support structure to an actuator, the support structure supporting a vertically aligned carbon nanotube array, and vibrating the support structure with the actuator. The method can also include the step of fixedly positioning the actuator between a first member and a second member. The vibration can be consistent or it can vary in amplitude and/or frequency over time. The step of fixedly positioning can include the first member having a first mass and the second member having a second mass that is different or less than the first mass. The actuator can include a piezoelectric element. A metalizing assembly for intercalating a vertically aligned carbon nanotube array with a metal includes a first member, a support structure, a second member and an actuator. The support structure is coupled to the first member. The support structure supports the vertically aligned carbon nanotube array.

Abstract: Multi-functional piezo-actuated flow control systems and methods for use in gas exchange analysis systems such as photosynthesis measurement systems. A fluid valve assembly module includes a housing structure including a plurality of ports and a plurality of fluid passageways interconnecting the ports, and a plurality of piezo-actuated valves in fluid communication with the fluid passageways, each valve including a piezo element that controls flow along a passageway, wherein the passageways and valves are arranged within the housing structure so as to define a fluid control module, which includes a flow swapping component, a flow splitting component and a flow pressurization component.

Abstract: An autonomous mobile sensor platform may be provided which may be capable of freely roaming within an environment. The mobile sensor platform may include a wheel that may be laterally self stabilizing, and capable and encircle a robot body. The mobile sensor platform may sense one or more conditions using one or more types of sensors and react based on the sensed conditions. Examples of reactions may include alerting a user about the conditions. The mobile sensor platform can be used to monitor an environment or individuals within the environment.

Abstract: An optical mirror element includes an optically transmissive element having a first surface and a second surface, and a reflective coating layer on the first surface that defines a mirror surface. A first portion of the first surface does not include the reflective coating layer such that the first portion defines an optically transmissive window in the mirror surface. Q method of forming an optical mirror element having a window portion includes providing an optical element, masking a first portion of a first surface of the optical element, and thereafter applying a reflective coating to the first surface so as to define a reflective surface, wherein the masked portion defines a transmissive region in the reflective surface. The exposed portion of the first surface may be coated with an anti-reflective coating, either before or after the reflective coating is applied.

Abstract: An optical mirror element includes an optically transmissive element having a first surface and a second surface, and a reflective coating layer on the first surface that defines a mirror surface. A first portion of the first surface does not include the reflective coating layer such that the first portion defines an optically transmissive window in the mirror surface. Q method of forming an optical mirror element having a window portion includes providing an optical element, masking a first portion of a first surface of the optical element, and thereafter applying a reflective coating to the first surface so as to define a reflective surface, wherein the masked portion defines a transmissive region in the reflective surface. The exposed portion of the first surface may be coated with an anti-reflective coating, either before or after the reflective coating is applied.

Abstract: Optical mirror elements having a diffusive backing, methods for making such optical mirror elements, and devices incorporating such optical mirror elements. The optical mirror element typically includes a first, reflective surface, and a second surface having uneven or granular features, wherein light passing through the first surface is diffusely reflected by the uneven or granular features of the second surface. The optical mirror elements are particularly well suited for use in Herriott Cell arrangements in gas analyzers.

Abstract: An optical mirror element includes an optically transmissive element having a first surface and a second surface, and a reflective coating layer on the first surface that defines a mirror surface. A first portion of the first surface does not include the reflective coating layer such that the first portion defines an optically transmissive window in the mirror surface. Q method of forming an optical mirror element having a window portion includes providing an optical element, masking a first portion of a first surface of the optical element, and thereafter applying a reflective coating to the first surface so as to define a reflective surface, wherein the masked portion defines a transmissive region in the reflective surface. The exposed portion of the first surface may be coated with an anti-reflective coating, either before or after the reflective coating is applied.

Abstract: Optical mirror elements having a diffusive backing, methods for making such optical mirror elements, and devices incorporating such optical mirror elements. The optical mirror element typically includes a first, reflective surface, and a second surface having uneven or granular features, wherein light passing through the first surface is diffusely reflected by the uneven or granular features of the second surface. The optical mirror elements are particularly well suited for use in Herriott Cell arrangements in gas analyzers.

Abstract: An optical mirror element includes an optically transmissive element having a first surface and a second surface, and a reflective coating layer on the first surface that defines a mirror surface. A first portion of the first surface does not include the reflective coating layer such that the first portion defines an optically transmissive window in the mirror surface. Q method of forming an optical mirror element having a window portion includes providing an optical element, masking a first portion of a first surface of the optical element, and thereafter applying a reflective coating to the first surface so as to define a reflective surface, wherein the masked portion defines a transmissive region in the reflective surface. The exposed portion of the first surface may be coated with an anti-reflective coating, either before or after the reflective coating is applied.

Abstract: A multi-pass optical cell with an actuator for actuating a reflective surface is provided. In one preferred embodiment, an apparatus is provided comprising a first reflective surface, a second reflective surface, and a support structure supporting the first and second reflective surfaces. The support structure positions the first and second reflective surfaces to create an optical cell. The apparatus also comprises a source and a detector, which are positioned such that light emitted from the source is reflected in the optical cell at least one time between the first and second reflective surfaces before reaching the detector. The apparatus further comprises an actuator coupled with and operative to actuate the first reflective surface. In some embodiments, the actuator rotates the first reflective surface. Also, in some embodiments, the multi-pass optical cell is an open path multi-pass optical cell, while, in other embodiments, the multi-pass optical cell is a closed path multi-pass optical cell.

Abstract: A digital signal processor having a generalized bit field extraction instruction which can be used to perform a bit field selection operation, a rotate left operation, a rotate right operation, a shift left operation, a logical shift right operation, an arithmetic shift right operation, and so forth.