Micro-structured Optics for Compact Atomic Clocks
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Solution Overview
Problem
Existing atomic clock designs face challenges in achieving compact size and low power consumption due to longer path lengths required for light beam diameter and inefficient heating methods, which compromise performance and stability in portable devices.
Innovation Solution
A micro-structured optics apparatus using a concave microlens to expand and a micro-Fresnel lens to collimate light, along with a reflector, is integrated into a compact physics package to minimize path length and power consumption, while co-locating the VCSEL and vapor cell for efficient heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a linear optics configuration with VCSEL spaced apart from vapor cell is used, then sufficient beam width can be achieved, but the physics package volume increases significantly
Solution Approach 1:
The patent transitions from a linear one-dimensional optics arrangement to a three-dimensional folded configuration. The optics are arranged in a folded path where light travels from VCSEL through a first lens, reflects off a mirror, passes through a second lens, and reaches the vapor cell. This spatial reconfiguration in multiple dimensions achieves the required beam width and illumination intensity while dramatically reducing the overall physics package volume by utilizing vertical and lateral space efficiently.
Solution Approach 2:
The patent implements nesting by co-locating the VCSEL and photodiode detector on the same chip or board, and by integrating multiple optical components (lenses, mirrors, beam splitters) into a compact folded arrangement. The optics are nested within a small volume where light paths are folded back on themselves, allowing multiple optical elements to occupy overlapping or adjacent spaces, thereby achieving sufficient beam width without proportionally increasing package volume.
2Temperature
If multiple window heaters are used to heat VCSEL and vapor cell, then temperature control is achieved, but power consumption increases
Solution Approach 1:
The patent merges the heating function by using a single window heater that simultaneously heats both the VCSEL and the vapor cell. Instead of employing separate heaters for each component, the design utilizes the shared window structure as a common thermal interface. This single heater is positioned to conduct heat through the window to both the VCSEL (for laser wavelength stabilization) and the vapor cell (for atomic vapor temperature control), thereby achieving temperature stability for both components while significantly reducing power consumption compared to multiple independent heating systems.
3Volume of stationary object
If folded optics configuration is used to reduce volume, then path length is minimized, but non-uniform light intensity and polarization are introduced
Solution Approach 1:
The patent introduces beam shaping optics (lenses and/or waveplates) as intermediary elements in the folded optical path to correct the non-uniform light intensity and polarization introduced by the folded configuration. These intermediary components are strategically placed within the folded optics arrangement to reshape the beam profile and uniformize the light distribution across the vapor cell, thereby compensating for the distortions caused by the compact folded geometry while maintaining the volume reduction benefits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration results in a significantly smaller and more power-efficient atomic clock with improved temperature stability and uniform light intensity, capable of producing timing signals with high accuracy and low instability.
Implementation Method 1
a concave microlens to expand a beam of light
Implementation Method 2
a reflector to provide a first reflection of at least a portion of the beam of light
Implementation Method 3
a micro-Fresnel lens to collimate the at least a portion of the beam of light after the expansion
Data Source
AI summary
A micro-structured optics apparatus includes a concave microlens to expand a beam of light, a reflector to provide a first reflection of at least a portion of the beam of light and a micro-Fresnel lens to collimate the at least a portion of the beam of light after the expansion.