Large aperture MEMS scanner module for 3D distance measurement

Abstract

In this article we present a new large aperture 1D-MEMS scanner module especially designed for laser radar systems. The scanner module has a resonance frequency of 250 Hz and optical scan range of 60°. It comprises of two separate scanning channels: (a) a single scanning mirror of the collimated transmitted beam oscillates parallel to (b) a scanning mirror array of the receiver optics. The receiver optics use a synchronized array of 2 x 7 identical mirror elements, each with 2.51x 9.51 mm² per single mirror element, resulting in a total aperture of 334 mm² and filling factor of 80 %. We discuss in detail the system integration of the MEMS components including packaging and synchronized operation of all scanner elements to guaranty a large aperture of the LIDAR receiver optics. In addition the paper includes a conceptual discussion of optical design and expected S/N ratio and measurement range of final LIDAR system. It will be shown that the presented new concept of MEMS based LIDAR system can realize also high accuracy of the distance measurement similar to state of the art TOF-LIDAR scanners enabling a new generation of miniaturized, robust and potentially cost efficient LIDAR systems due to the MEMS technology

Single Chip LIDAR with Discrete Beam Steering by Digital Micromirror Device

“…and scan rates of 21 kHz [2,10]. However, a resonant mirror's maximum beam diameter is only increased at the expense of decreasing the maximum scan rate [9].…”

High-uniformity centimeter-wide Si etching method for MEMS devices with large opening elements

“…In some application fields, in contrast, the MEMS structure is becoming larger owing to its application requirements. Laser scanner [4][5][6] and energy harvesting devices 7,8) are typical applications that require large MEMS fabrication.…”

“…In this example, the resist almost disappeared after 123 cycles, probably owing to the smaller heat exchange. Then only SF 6 isotropic etching was performed with 300 sccm SF 6 , a coil power of 1800 W, and a bias power of 50 W. The SF 6 isotropic etching was stopped every 4 min and the chip was optically observed. Figure 14 shows photographs of the progress of the isotropic etching.…”

Multi-beam and single-chip LIDAR with discrete beam steering by digital micromirror device

“…2,10 However, a resonant mirror's maximum beam diameter is only increased at the expense of decreasing the maximum scan rate. 9 An optical amplification of the steering angle by an inverse telescope design has been reported; however, this design requires a reduced beam diameter to conserve the Lagrange invariant, which would limit the effective delivery of light over large distances due to beam spreading by diffraction.…”