ATOMIC SOURCE WITH HEATER ON THERMAL ISOLATION DIE

• US 20150226669A1
• Filed: 04/09/2014
• Published: 08/13/2015
• Est. Priority Date: 02/12/2014
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Compton, Robert
• Granted Patent: US 9,983,131 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01K 13/02 for measuring temperature of moving fluids or granular materials capable of flow
• CPC Class Codes: G01K 7/00 Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat giving results other than momentary value of temperature G01K3/00 ; Power supply therefor, e.g. using thermoelectric elements
• CPC Class Codes: G01N 1/28 Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Qmounting specimens on microscopic slides G02B21/34; means for supporting the objects or the materials to be analysed in electron microscopes H01J37/20 ; laboratory gas handling apparatus B01L5/00
• CPC Class Codes: G01N 21/6404 Atomic fluorescence
• CPC Class Codes: G04F 5/145 using Coherent Population Trapping
• CPC Class Codes: H03B 17/00 Generation of oscillations using radiation source and detector, e.g. with interposed variable obturator

Abstract

In one embodiment, a chip scale atomic sensor is provided. The chip scale atomic sensor includes a body that defines at least one sensing chamber. The body includes a thermal isolation die mounted to the body. The thermal isolation die is disposed in a location that communicates with the at least one sensing chamber. The thermal isolation die includes a substrate defining a frame portion and an isolated portion and a plurality of tethers mechanically coupling the isolated portion of the substrate to the frame portion. The thermal isolation die also includes an atomic source mounted on the isolated portion of the substrate, and a heating element mounted on the isolated portion and configured to heat the atomic source.

Claims

1. A chip scale atomic sensor comprising:

a body that defines at least one sensing chamber;

a thermal isolation die mounted to the body, the thermal isolation die disposed in a location that communicates with the at least one sensing chamber, the thermal isolation die including;

a substrate defining a frame portion and an isolated portion;

a plurality of tethers mechanically coupling the isolated portion of the substrate to the frame portion;

an atomic source mounted on the isolated portion of the substrate; and

a heating element on the isolated portion and configured to heat the atomic source.

2. The chip scale atomic sensor of claim 1, wherein the thermal isolation die includes a temperature sensor disposed on the isolated portion, the temperature sensor configured to sense a temperature proximate the atomic source,

wherein the chip scale atomic sensor includes control electronics configured to obtain temperature readings from the temperature sensor and control the heating element to maintain the temperature proximate the atomic source at a temperature set point.

3. The chip scale atomic sensor of claim 2, wherein the temperature sensor is a Wheatstone bridge.

4. The chip scale atomic sensor of claim 2, wherein the thermal isolation die includes a plurality of electrical leads disposed in part on the plurality of tethers, the plurality of electrical leads electrically coupled to the heating element and the temperature sensor.

5. The chip scale atomic sensor of claim 2, comprising:

a laser disposed to emit light into the sensing chamber, wherein the laser is locked to an atomic hyperfine transition of alkali atoms of the atomic source; and

a photodetector disposed to sense light in the sensing chamber indicative of the vapor pressure in the sensing chamber,

wherein the control electronics are configured to receive a signal from the photodetector and to control the heating element based thereon to maintain a desired vapor pressure of alkali atoms within the sensing chamber.

6. The chip scale atomic sensor of claim 5, wherein the photodetector is aligned with and configured to sense light emitted by the laser after the light passes through a vapor cloud of alkali atoms in the sensing chamber.

7. The chip scale atomic sensor of claim 5, wherein the photodetector is disposed to sense fluorescence emitted by alkali atoms in a vapor cloud in the sensing chamber after the alkali atoms absorb light from the laser.

8. The chip scale atomic sensor of claim 5, wherein the photodetector is mounted on the isolated portion of the thermal isolation die.

9. The chip scale atomic sensor of claim 8, wherein the laser is mounted on an isolated portion of a second thermal isolation die.

10. The chip scale atomic sensor of claim 5, wherein the control electronics are configured to adjust the temperature set point based on the signal indicative of vapor pressure from the photodetector to maintain a vapor pressure in the sensing chamber.

11. The chip scale atomic sensor of claim 1, wherein the plurality of tethers are defined in the substrate.

12. The chip scale atomic sensor of claim 1, wherein the substrate is composed of silicon.

13. The chip scale atomic sensor of claim 1, wherein the atomic source includes one of a compound of an alkali and another element, an alloy of an alkali and another metal, or a graphite intercalation compound including an alkali.

14. The chip scale atomic sensor of claim 1, wherein the thermal isolation die is disposed within the sensing chamber, in a recess that opens to the sensing chamber, or in a secondary chamber that communicates with the sensing chamber.

15. A method of controlling a vapor pressure in a chip scale atomic sensor, the method comprising:

sensing a temperature proximate an atomic source;

controlling a heating element proximate the atomic source based on the sensed temperature to maintain the temperature proximate the atomic source at a temperature set point;

emitting light from a laser toward a vapor cloud of alkali atoms in a sensing chamber of the chip scale atomic sensor;

sensing light in the sensing chamber, the light indicative of a vapor pressure of alkali atoms in the sensing chamber; and

adjusting the temperature set point based on the sensed light in the sensing chamber to maintain the vapor pressure in the sensing chamber at a desired level.

16. The method of claim 15, wherein sensing light includes one or more of sensing light emitted by the laser that passed through the vapor cloud and sensing fluorescence emitted by the alkali atoms after the alkali atoms absorb light from the laser.

17. A chip scale atomic sensor comprising:

a body that defines a sensing chamber;

a thermal isolation die mounted to the body, the thermal isolation die disposed in a location that communicates with the sensing chamber, the thermal isolation die including;

a substrate composed of silicon, the substrate defining a frame portion, an isolated portion, and a plurality of tethers mechanically extending between the isolated portion and the frame portion, wherein plurality of tethers extend through a gap in the substrate between the frame portion and the isolated portion;

an atomic source mounted on the isolated portion of the substrate;

a heating element on the isolated portion of the substrate; and

a plurality of electrical leads disposed in part on the plurality of tethers, the plurality of leads electrically coupled to the heater.

18. The chip scale atomic sensor of claim 17, comprising:

a laser disposed to emit light into the sensing chamber, wherein the laser is locked to an atomic hyperfine transition of alkali atoms of the atomic source; and

a photodetector disposed to sense light in the sensing chamber indicative of the vapor pressure in the sensing chamber,

wherein the control electronics are configured to receive a signal from the photodetector and to control the heating element based thereon to maintain a desired vapor pressure of alkali atoms within the sensing chamber.

19. The chip scale atomic sensor of claim 18, wherein the thermal isolation die includes a temperature sensor disposed on the isolated portion, the temperature sensor configured to sense a temperature proximate the atomic source,

wherein the chip scale atomic sensor includes control electronics configured to obtain temperature readings from the temperature sensor and control the heating element to maintain the temperature proximate the atomic source at a temperature set point.

20. The chip scale atomic sensor of claim 19, wherein the control electronics are configured to adjust the temperature set point based on the signal indicative of vapor pressure from the photodetector to maintain a vapor pressure in the sensing chamber.