On-Chip Frequency Tuning of Fast Resonant MEMS Scanner

Abstract

The development and characterisation of a piezoelectric actuated high-frequency MEMS scanning mirror with on-chip frequency tuning capability is reported. The resonant scanner operates at frequencies in excess of 140 kHz, generating scan angles of 10° and 6° for two orthogonal movement modes with 40 V actuation. On-chip frequency tuning is achieved through electrothermal actuators fabricated adjacent to the mirror main suspension. The electrothermal actuators produce a global and local temperature increase which changes the suspension stiffness and therefore the resonant frequency. A resonance frequency tuning range of up to 5.5 kHz is achieved, with tuning dominant on only one of the two orthogonal scan movement modes. This opens the possibility for precise tuning of a 2D Lissajous scan pattern using a single resonant MEMS scanner with dual orthogonal resonant modes producing full frame update rates up to 20 kHz while retaining the full angular range of both resonant movement modes.

Increasing MEMS Micromirror Line-Scan Rates through 3D-Printed Micro-Optics

“…Each of the mentioned implementations has their unique advantages, but all have a limitation in their maximum scan speed based on material properties and their size, with larger structures of higher mass having inherently reduced resonance frequencies and scan speeds [1]. MEMS scanners have the advantage of a reduced size and mass, which allow resonance scan frequencies to be pushed up to several 100 kHz, albeit with small mirror sizes <500 µm diameter [2]. In most applications, mirror diameters of 1 mm or larger are required, which therefore reduce the maximum achievable scan frequencies to below 50 kHz, with MEMS scanners providing the highest resonance speeds.…”

Cold-atom shaping with MEMS scanning mirrors

“…The scanners themselves are custom built resonant piezoelectric MEMS with 400 µm mirror aperture fabricated using a commercial multiuser process (MEMSCAP PiezoMUMPS) [28]. The scanner design is shown in Fig.…”

“…This concept is described in detail in Ref. [28]. Through thermal tuning, the resonance frequency can be reduced by around 1.5 kHz, from 91.5 to 90 kHz, making actuation at 90 kHz possible with sufficient optical scan amplitude for synchronized scanning purposes.…”