Hyperspectral MEMS Tunable Filter Calibration for Manufacturing Variations
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Solution Overview
Problem
Manufacturing variations in MEMS-based tunable filters lead to performance differences, necessitating tools for monitoring and identifying the exact state of these devices to overcome manufacturing differences and defects.
Innovation Solution
A calibration device and method that directs light towards different portions of a tunable filter, detects optical responses, and uses a light selective unit to determine the filter's state by analyzing optical gaps and tilt values, with a processing circuitry to apply and store actuation parameters for achieving desired filter states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manufacturing processes are used to produce MEMS-based tunable filters, then devices can be produced, but manufacturing variations lead to performance differences between devices
Solution Approach 1:
The patent applies parameter changes by measuring the actual optical parameters (central wavelength, FWHM, tilt angle) of each filter and adjusting the actuation parameters accordingly. This allows each device to be calibrated to its specific manufacturing characteristics, compensating for variations while maintaining high productivity.
Solution Approach 2:
The patent implements feedback by measuring the optical response of each filter and using this information to determine the appropriate actuation parameters. The system continuously monitors performance and adjusts parameters to achieve desired spectral characteristics, ensuring consistent performance across devices despite manufacturing variations.
2Measurement precision
If calibration measurements are performed on each portion of the tunable filter, then the exact state can be determined, but the calibration process becomes time-consuming
Solution Approach 1:
The patent segments the filter surface into multiple portions and measures each portion separately using different illumination angles. This allows comprehensive characterization of the filter's optical state while enabling parallel processing and efficient data collection, reducing overall calibration time.
Solution Approach 2:
The patent uses periodic illumination at different angles to sequentially measure different portions of the filter. By systematically varying illumination parameters in a periodic manner, the system efficiently collects all necessary measurement data without requiring continuous complex operations, thereby reducing calibration time.
3Reliability
If multiple actuation parameters are adjusted to achieve desired filter states, then performance can be optimized, but the control system becomes more complex
Solution Approach 1:
The patent changes actuation parameters (voltage, current) based on measured optical parameters to achieve desired filter states. By systematically adjusting these parameters according to measured deviations, the system optimizes performance while maintaining a relatively simple control architecture that builds upon standard MEMS actuation mechanisms.
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
Accurately determines and calibrates the state of tunable filters by aligning optical gaps and angular positions within tolerance ranges, ensuring consistent performance across devices.
Implementation Method 1
a light source configured to emit light, wherein light originated from the light source passes through the light selective unit to reach the tunable filter
Implementation Method 2
An etalon comprises two parallel mirrors where the spectral transmission profile of the filter is determined by a respective 'filter-state' defined by the specific gap between the mirrors (which provides a so called 'optical cavity' or 'optical gap')
Implementation Method 3
a tunable filter may be actuated by application of voltage difference between a movable member and a stationary member that results in electrostatic forces between the members
Data Source
AI summary
According to one aspect of the presently disclosed subject there is provided a device configured figured to allow illumination of light towards a tunable filter, each time towards a different portion thereof, and detect the optical response, (e.g., transmission or reflection from the portion that is illuminated with light). By detecting optical response of isolated illuminations towards different portions of the tunable filter each time, the state of the tunable filter at the illuminated portion, e.g. the optical gap between a movable member and a stationary member of the tunable filter, can be determined. By monitoring different portions of the tunable filter, the general state of the tunable filter is determined. For example, the general state of the tunable filter may be determined based on the optical gaps at different portions of the tunable filter while the actuation parameters are maintained unchanged.