Monitoring of MEMS mirror properties
Systems and methods are provided for monitoring properties of a microelectromechanical systems (MEMS) oscillating structure. A system includes a MEMS oscillating structure configured as a non-linear resonator to oscillate about a rotation axis; a driver configured to generate a driving force for driving the MEMS oscillating structure about the rotation axis according to an operating response curve during which the MEMS oscillating structure is in resonance, the driver further configured to decrease the driving force when the MEMS oscillating structure is at a predefined tilt angle to induce an oscillation decay of the MEMS oscillating structure; a measurement circuit configured to measure an oscillation frequency and a tilt angle amplitude of the MEMS oscillating structure during a decay period; and processing circuitry configured to determine at least one characteristic of the MEMS oscillating structure based on at least one of the measured oscillation frequency and the measured tilt angle amplitude.
1. A system, comprising:
a microelectromechanical systems (MEMS) oscillating structure configured as a non-linear resonator to oscillate about a rotation axis;
a driver configured to generate a driving force for driving the MEMS oscillating structure about the rotation axis according to an operating response curve during which the MEMS oscillating structure is in resonance, the driver further configured to decrease the driving force when the MEMS oscillating structure is at a predefined tilt angle to induce an oscillation decay of the MEMS oscillating structure over a decay period;
a measurement circuit configured to measure at least one characteristic of the oscillation decay; and
at least one processor configured to determine a mechanical health of the MEMS oscillating structure based on the at least one characteristic of the oscillation decay.
2. The system of claim 1 , wherein the at least one characteristic of the oscillation decay is an oscillation frequency of the MEMS oscillating structure during the decay period.
3. The system of claim 1 , wherein the oscillation frequency is a zero-angle frequency of the MEMS oscillating structure.
4. The system of claim 3 , wherein the measurement circuit is configured to measure the zero-angle frequency based on the MEMS oscillating structure oscillating through a zero-angle range during the oscillation decay.
5. The system of claim 4 , wherein at least one processor is configured to compare the zero-angle frequency with an expected zero-angle frequency, and determine the mechanical health of the MEMS oscillating structure based on the comparison.
6. The system of claim 1 , wherein the at least one characteristic of the oscillation decay is a tilt angle amplitude of the MEMS oscillating structure during the decay period.
7. The system of claim 6 , wherein the at least one processor is configured to generate a tilt angle amplitude decay curve based on the measured tilt angle amplitude, compare the tilt angle amplitude decay curve with a previous tilt angle amplitude decay curve, determine the mechanical health of the MEMS oscillating structure based on the comparison.
8. The system of claim 1 , wherein the at least one characteristic of the oscillation decay is a duration of the decay period.
9. The system of claim 1 , wherein the at least one characteristic of the oscillation decay is an angle decay slope of the MEMS oscillating structure during the decay period.
10. The system of claim 1 , wherein:
the at least one characteristic of the oscillation decay includes a first angle decay slope of the MEMS oscillating structure initiated at a first predefined tilt angle and a second angle decay slope of the MEMS oscillating structure initiated at a second predefined tilt angle less than the first predefined tilt angle, and
the at least one processor is configured to calculate a ratio between the first angle decay slope and the second angle decay slope, calculate a difference between the determined ratio and a reference ratio, and determine the mechanical health of the MEMS oscillating structure based the calculated difference.
11. The system of claim 10 , wherein the at least one processor is configured to compare the calculated difference to a threshold value, and generate a failure signal on a condition that the calculated difference exceeds the threshold value.
12. A system, comprising:
a chip package including a microelectromechanical systems (MEMS) oscillating structure encapsulated in the chip package, the MEMS oscillating structure configured as a non-linear resonator to oscillate about a rotation axis;
a driver configured to generate a driving force for driving the MEMS oscillating structure about the rotation axis according to an operating response curve during which the MEMS oscillating structure is in resonance, the driver further configured to decrease the driving force when the MEMS oscillating structure is at a predefined tilt angle to induce an oscillation decay of the MEMS oscillating structure over a decay period;
a measurement circuit configured to measure at least one characteristic of the oscillation decay; and
at least one processor configured to determine a mechanical health of the chip package based on the at least one characteristic of the oscillation decay.
13. The system of claim 12 , wherein the at least one characteristic of the oscillation decay is an oscillation frequency of the MEMS oscillating structure during the decay period.
14. The system of claim 12 , wherein the at least one characteristic of the oscillation decay is a tilt angle amplitude of the MEMS oscillating structure during the decay period.
15. The system of claim 14 , wherein the at least one processor is configured to generate a tilt angle amplitude decay curve based on the measured tilt angle amplitude, compare the tilt angle amplitude decay curve with a previous tilt angle amplitude decay curve, determine the mechanical health of the MEMS oscillating structure based on the comparison.
16. The system of claim 12 , wherein the at least one characteristic of the oscillation decay is a duration of the decay period.
17. The system of claim 12 , wherein the at least one characteristic of the oscillation decay is an angle decay slope of the MEMS oscillating structure during the decay period.
18. The system of claim 12 , wherein:
the at least one characteristic of the oscillation decay includes a first angle decay slope of the MEMS oscillating structure initiated at a first predefined tilt angle and a second angle decay slope of the MEMS oscillating structure initiated at a second predefined tilt angle less than the first predefined tilt angle, and
the at least one processor configured to calculate a ratio between the first angle decay slope and the second angle decay slope, calculate a difference between the determined ratio and a reference ratio, and determine the mechanical health of the chip package based the calculated difference.
19. The system of claim 18 , wherein the at least one processor is configured to compare the calculated difference to a threshold value, and generate a failure signal on a condition that the calculated difference exceeds the threshold value.
20. The system of claim 12 , wherein:
the at least one processor is configured to determine a pressure inside the MEMS package based on the at least one characteristic of the oscillation decay, compare the determined pressure to an expected pressure to generate a comparison result, and determine the mechanical health of the chip package based the comparison result.
21. The system of claim 20 , wherein the at least one processor is configured to detect a leak in the chip package based on the comparison result and generate a failure signal in response to the detected leak.