Abstract: Techniques are described for sensing a position of an object located within an enclosure over a position range. The techniques include generating an expected output signal of each of a plurality of magnetic field sensors disposed along an outer surface of the enclosure, receiving actual output signals from the sensors, wherein each actual output signal indicates a relative proximity of a magnetic target coupled to the object to the corresponding sensor. The techniques further include superimposing the expected output signal over the actual output signals, and iteratively shifting the expected output signal over position relative to the actual output signals and comparing the shifted expected output signal to the actual output signals, until the expected output signal compared to the actual output signals corresponds to a substantially minimized error parameter. The position of the object may then be determined based at least in part on the shifted expected output signal.

Abstract: A method of fabricating vapor cells comprises forming a plurality of vapor cell dies in a first wafer having an interior surface region and a perimeter, and forming a plurality of interconnected vent channels in the first wafer. The vent channels provide at least one pathway for gas from each vapor cell die to travel outside of the perimeter of the first wafer. The method further comprises anodically bonding a second wafer to one side of the first wafer, and anodically bonding a third wafer to an opposing side of the first wafer. The vent channels allow gas toward the interior surface region of the first wafer to be in substantially continuous pressure-equilibrium with gas outside of the perimeter of the first wafer during the anodic bonding of the second and third wafers to the first wafer.

Abstract: A method of fabricating one or more vapor cells comprises forming one or more vapor cell dies in a first wafer having a first diameter, and anodically bonding a second wafer to a first side of the first wafer over the vapor cell dies, the second wafer having a second diameter. A third wafer is positioned over the vapor cell dies on a second side of the first wafer opposite from the second wafer, with the third wafer having a third diameter. A sacrificial wafer is placed over the third wafer, with the sacrificial wafer having a diameter that is larger than the first, second and third diameters. A metallized bond plate is located over the sacrificial wafer. The third wafer is anodically bonded to the second side of the first wafer when a voltage is applied to the metallized bond plate while the sacrificial wafer is in place.

Abstract: Techniques are described for sensing a position of an object located within an enclosure over a position range. The techniques include generating an expected output signal of each of a plurality of magnetic field sensors disposed along an outer surface of the enclosure, receiving actual output signals from the sensors, wherein each actual output signal indicates a relative proximity of a magnetic target coupled to the object to the corresponding sensor. The techniques further include superimposing the expected output signal over the actual output signals, and iteratively shifting the expected output signal over position relative to the actual output signals and comparing the shifted expected output signal to the actual output signals, until the expected output signal compared to the actual output signals corresponds to a substantially minimized error parameter. The position of the object may then be determined based at least in part on the shifted expected output signal.

Abstract: A method of fabricating vapor cells comprises forming a plurality of vapor cell dies in a first wafer having an interior surface region and a perimeter, and forming a plurality of interconnected vent channels in the first wafer. The vent channels provide at least one pathway for gas from each vapor cell die to travel outside of the perimeter of the first wafer. The method further comprises anodically bonding a second wafer to one side of the first wafer, and anodically bonding a third wafer to an opposing side of the first wafer. The vent channels allow gas toward the interior surface region of the first wafer to be in substantially continuous pressure-equilibrium with gas outside of the perimeter of the first wafer during the anodic bonding of the second and third wafers to the first wafer.

Abstract: A method of fabricating vapor cells comprises forming a plurality of vapor cell dies in a first wafer having an interior surface region and a perimeter, and forming a plurality of interconnected vent channels in the first wafer. The vent channels provide at least one pathway for gas from each vapor cell die to travel outside of the perimeter of the first wafer. The method further comprises anodically bonding a second wafer to one side of the first wafer, and anodically bonding a third wafer to an opposing side of the first wafer. The vent channels allow gas toward the interior surface region of the first wafer to be in substantially continuous pressure-equilibrium with gas outside of the perimeter of the first wafer during the anodic bonding of the second and third wafers to the first wafer.

Abstract: A method to construct a chip-scale atomic clock is provided. The method comprises providing a scaffolding for components in a chip-scale atomic clock. The components include a laser and at least one other component. The method also includes operationally positioning the components on the scaffolding so that an emitting surface of the laser is non-parallel to partially reflective surfaces of the at least one other component.

Abstract: Designs and processes for thermally stabilizing a vertical cavity surface emitting laser (vcsel) in a chip-scale atomic clock are provided. In one embodiment, a Chip-Scale Atomic Clock includes: a vertical cavity surface emitting laser (vcsel); a heater block coupled to a base of the vcsel; a photo detector; a vapor cell, wherein the vapor cell includes a chamber that defines at least part of an optical path for laser light between the vcsel and the photo detector; and an iso-thermal cage surrounding the vcsel on all sides, the iso-thermal cage coupled to the heater block via a thermally conductive path.

Abstract: An optical-based acoustic sensor system detects sound. An exemplary embodiment has a substrate with a surface and an internal region; a shell disposed above the substrate surface, the shell operable to receive incident light emitted by a light source; a beam disposed blow the shell; a photodiode on the substrate surface below the beam, and in response to receiving a first portion of light, the photodiode is operable to generate a charge that attracts the beam such that a motion is induced in the beam to cause the beam to resonate; and a microphone device coupled to the shell, the microphone device operable to detect acoustic waves, and operable to modulate the vibratory motion of the beam, wherein a second portion of light is modulated by the vibratory motion of the beam to generate sound-modulated light that is emitted from the sensor.

Abstract: A chip-scale atomic clock comprises a physics package and a laser die located in a first thermal zone of the physics package. A quarter wave plate is mounted in the physics package and is in optical communication with the laser die. A vapor cell is mounted in the physics package and is in optical communication with the quarter wave plate. The vapor cell is located in a second thermal zone that is independent from the first thermal zone. An optical detector is mounted in the physics package and is in optical communication with the vapor cell. The first thermal zone provides a first operation temperature at a first stability point associated with the laser die, and the second thermal zone provides a second operation temperature at a second stability point associated with the vapor cell.

Abstract: A method of fabricating vapor cells comprises forming a plurality of vapor cell dies in a first wafer having an interior surface region and a perimeter, and forming a plurality of interconnected vent channels in the first wafer. The vent channels provide at least one pathway for gas from each vapor cell die to travel outside of the perimeter of the first wafer. The method further comprises anodically bonding a second wafer to one side of the first wafer, and anodically bonding a third wafer to an opposing side of the first wafer. The vent channels allow gas toward the interior surface region of the first wafer to be in substantially continuous pressure-equilibrium with gas outside of the perimeter of the first wafer during the anodic bonding of the second and third wafers to the first wafer.

Abstract: Designs and processes for thermally stabilizing a vertical cavity surface emitting laser (vcsel) in a chip-scale atomic clock are provided. In one embodiment, a Chip-Scale Atomic Clock includes: a vertical cavity surface emitting laser (vcsel); a heater block coupled to a base of the vcsel; a photo detector; a vapor cell, wherein the vapor cell includes a chamber that defines at least part of an optical path for laser light between the vcsel and the photo detector; and an iso-thermal cage surrounding the vcsel on all sides, the iso-thermal cage coupled to the heater block via a thermally conductive path.

Abstract: A chip-scale atomic clock comprises a physics package and a laser die located in a first thermal zone of the physics package. A quarter wave plate is mounted in the physics package and is in optical communication with the laser die. A vapor cell is mounted in the physics package and is in optical communication with the quarter wave plate. The vapor cell is located in a second thermal zone that is independent from the first thermal zone. An optical detector is mounted in the physics package and is in optical communication with the vapor cell. The first thermal zone provides a first operation temperature at a first stability point associated with the laser die, and the second thermal zone provides a second operation temperature at a second stability point associated with the vapor cell.

Abstract: A method to construct a chip-scale atomic clock is provided. The method comprises providing a scaffolding for components in a chip-scale atomic clock. The components include a laser and at least one other component. The method also includes operationally positioning the components on the scaffolding so that an emitting surface of the laser is non-parallel to partially reflective surfaces of the at least one other component.

Abstract: Apparatus and methods for alkali vapor cells are provided. In one embodiment, a vapor cell for a Chip-Scale Atomic Clocks (CSAC) comprises a silicon wafer having defined within a first chamber, a second chamber, and a pathway connecting the first chamber to the second chamber; a first glass wafer anodically-bonded to a first surface of the silicon wafer; a second glass wafer anodically-bonded to an opposing second surface of the silicon wafer, wherein the first chamber defines an optical path through the vapor cell; and an alkali metal material deposited into the second chamber. The pathway connecting the first chamber to the second chamber is configured with a geometry that is at least partially inhibitive to alkali metal vapor flow.

Abstract: A start-up circuit having a micro crush capacitor that is operatable with a small pressure. The crush capacitor may be connected to a silicon controlled rectifier or similar device. Applying the pressure to the crush capacitor may turn on the SCR which may in turn activate a sensor. The circuit may be fabricated on a flexible substrate which together may be regarded as a flexible circuit. The flexible circuit may be held down on a back plate with a form plate clamping the circuit at its perimeter edge. The flexible circuit may be held firm with the plates for component insertion and/or circuit testing.

Abstract: A physic package for an atomic clock comprising: a block made of optical glass, a glass ceramic material or another suitable material that includes a plurality of faces on its exterior and a plurality of angled borings that serve as a vacuum chamber cavity, light paths and measurement bores; mirrors fixedly attached using a vacuum tight seal to the exterior of the block at certain locations where two light paths intersect; optically clear windows fixedly attached using a vacuum tight seal to the block's exterior over openings of the measurement bores and at one location where two light paths intersect; and fill tubes fixedly attached using a vacuum tight seal to the exterior of the block over the ends of the vacuum chamber cavity. This physics package design makes possible atomic clocks having reduced size and power consumption and capable of maintaining an ultra-high vacuum without active pumping.

Abstract: An atomic clock having a physics package that includes a vacuum chamber cavity that holds atoms of Rb-87 under high vacuum conditions, an optical bench having a single laser light source, a local oscillator, a plurality of magnetic field coils, an antenna, at least one photo-detector and integrated control electronics. The single laser light source has a fold-retro-reflected design to create three retro-reflected optical beams that cross at 90° angles relative to one another in the vacuum chamber cavity. This design allows the single laser light source to make the required six trapping beams needed to trap and cool the atoms of Rb-87. The foregoing design makes possible atomic clocks having reduced size and power consumption and capable of maintaining an ultra-high vacuum without active pumping.

Abstract: A method and system for detecting concealed weapons and explosives by imaging THz scenes using conventional optics and detectors is provided. Photon fields with two different wavelengths can be sent through a chopper and towards a wavelength-selective mirror. A light beam with a wavelength in the visible or IR range is sent toward a visible photon array detector. Similarly, light beams with wavelengths in the THz range can be sent towards a target, which are reflected and/or absorbed by objects in the target. The reflected or transmitted light continues on through an optional filter to remove background light, then into a non-imaging detector. The visible photon array detector can be coupled with the non-imaging detector, which will register an image of the scene that is illuminated by the THz photons.

Abstract: A physic package for an atomic clock comprising: a block made of optical glass, a glass ceramic material or another suitable material that includes a plurality of faces on its exterior and a plurality of angled borings that serve as a vacuum chamber cavity, light paths and measurement bores; mirrors fixedly attached using a vacuum tight seal to the exterior of the block at certain locations where two light paths intersect; optically clear windows fixedly attached using a vacuum tight seal to the block's exterior over openings of the measurement bores and at one location where two light paths intersect; and fill tubes fixedly attached using a vacuum tight seal to the exterior of the block over the ends of the vacuum chamber cavity. This physics package design makes possible atomic clocks having reduced size and power consumption and capable of maintaining an ultra-high vacuum without active pumping.