Abstract: A pressure sensor includes a diaphragm having a displaceable elastic inner portion, wherein the inner portion displaces in response to a pressure difference between first and second sides of the diaphragm. A radiation source may be configured to transmit first and second beams of radiation. A light receiver may be configured to receive the first beam of radiation directly from the radiation source and the second beam of radiation after it reflects from the first side of the diaphragm. A control system may be coupled to the radiation source and light receiver and adapted to determine the pressure difference from the displacement of the diaphragm.

Abstract: A laser beam may be used to provide a virtual reference axis of travel for the in-axis direction of motion of lenses in a zoom assembly to be positioned during a zoom operation. The virtual reference axis is projected along the optical axis, parallel to existing mechanical lens slides. The virtual reference axis passes through an aperture on each of the lens assemblies, and is sampled by a set of optics and detectors on each of the lens assemblies. The optics and detectors are arranged such that any change in the position of a lens cell within a lens assembly relative to the virtual reference axis is sensed and corrected using a feedback signal to a positioning motor. Since the same virtual reference axis is used for each lens in the zoom assembly, each lens can be independently corrected for off-axis position errors to very high precision.

Abstract: An apparatus and method for precisely detecting very small distances between a measurement probe and a surface, and more particularly to a proximity sensor using a constant liquid flow and sensing a liquid mass flow rate within a bridge to detect very small distances. Within the apparatus the use of a flow restrictor and/or snubber made of porous material and/or a liquid mass flow rate controller enables detection of very small distances in the nanometer to sub-nanometer range. A further embodiment wherein a measurement channel of a proximity sensor is connected to multiple measurement branches.

Abstract: An apparatus and method for precisely detecting very small distances between a measurement probe and a surface, and more particularly to a proximity sensor using a constant gas flow and sensing a mass flow rate within a pneumatic bridge to detect very small distances. Within the apparatus the use of a flow restrictor and/or snubber made of porous material and/or a mass flow rate controller enables detection of very small distances in the nanometer to sub-nanometer range. A further embodiment wherein a measurement channel of a proximity sensor is connected to multiple measurement branches.

Abstract: A pressure gauge includes a diaphragm having a substantially rigid outer portion and a displaceable inner portion that displaces in response to a pressure difference between first and second sides of the diaphragm. The pressure gauge further includes a sensor located proximate to the diaphragm and adapted to sense the displacement of the diaphragm inner portion. The pressure gauge further includes a monitor and control system coupled to the sensor (wired or wireless), and adapted to determine the pressure difference from the displacement of the diaphragm. The sensor and the monitor and control system can be implemented with one or more optical sensing designs, capacitive sensing designs, or other devices used to measure sub-micron displacements. For low pressure applications, such as lithography applications, the diaphragm is sensitive to pressure changes in a range of approximately 0.1 to 0.5 inches of water.