Systems and methods for concentrating alkali metal within a vapor cell of a magnetometer away from a transit path of light

A wearable sensor unit comprising:

• a magnetometer comprising
• a vapor cell comprising an input window and containing an alkali metal, and
• a light source configured to output light that passes through the input window and into the vapor cell along a transit path;
• and
• a temperature control circuit external to the vapor cell and configured to create a temperature gradient within the vapor cell by creating one or more hot spots on an inner surface of the vapor cell that are hotter by at least a threshold number of degrees than other locations on the inner surface of the vapor cell, the temperature gradient configured to concentrate the alkali metal within the vapor cell away from the transit path of the light;
• wherein the temperature control circuit comprises a printed circuit board (PCB) that includes:
• an input aperture configured to align with and be above the input window of the vapor cell such that the light passes through the input aperture before passing through the input window;
• a heat generating element configured to generate heat;
• a thermal contact on a first side of the input aperture and thermally connected to the heat generating element, the thermal contact configured to create the one or more hot spots by directing the heat from the heat generating element to the vapor cell;
• and
• a thermal path out on a second side of the input aperture, the thermal path out configured to assist in creating the temperature gradient within the vapor cell;
• wherein the temperature gradient is configured to concentrate the alkali metal within the vapor cell closer to the thermal path out than to the thermal contact.