Frequency-modulated laser ranging sensor with closed-loop control

Fabian M. Müller; Gunnar Böttger; Christian Janeczka; Norbert Arndt-Staufenbiel; Henning Schröder; Martin Schneider-Ramelow

doi:10.1117/12.2289585

22 February 2018 Frequency-modulated laser ranging sensor with closed-loop control

Fabian M. Müller, Gunnar Böttger, Christian Janeczka, Norbert Arndt-Staufenbiel, Henning Schröder, Martin Schneider-Ramelow

Author Affiliations +

Proceedings Volume 10539, Photonic Instrumentation Engineering V; 1053909 (2018) https://doi.org/10.1117/12.2289585
Event: SPIE OPTO, 2018, San Francisco, California, United States

Abstract

Advances in autonomous driving and robotics are creating high demand for inexpensive and mass-producible distance sensors. A laser ranging system (Lidar), based on the frequency-modulated continuous-wave (FMCW) method is built in this work. The benefits of an FMCW Lidar system are the low-cost components and the performance in comparison to conventional time-of-flight Lidar systems. The basic system consists of a DFB laser diode (λ= 1308 nm) and an asymmetric fiber-coupled Mach-Zehnder interferometer with a fixed delay line in one arm. Linear tuning of the laser optical frequency via injection current modulation creates a beat signal at the interferometer output. The frequency of the beat signal is proportional to the optical path difference in the interferometer. Since the laser frequency-to-current response is non-linear, a closed-loop feed-back system is designed to improve the tuning linearity, and consequently the measurement resolution. For fast active control, an embedded system with FPGA is used, resulting in a nearly linear frequency tuning, realizing a narrow peak in the Fourier spectrum of the beat signal. For free-space measurements, a setup with two distinct interferometers is built. The fully fiber-coupled Mach-Zehnder reference interferometer is part of the feed-back loop system, while the other - a Michelson interferometer - has a free-space arm with collimator lens and reflective target. A resolution of 2:0 mm for a 560 mm distance is achieved. The results for varying target distances show high consistency and a linear relation to the measured beat-frequency.

Conference Presentation

Citation Download Citation

Fabian M. Müller, Gunnar Böttger, Christian Janeczka, Norbert Arndt-Staufenbiel, Henning Schröder, and Martin Schneider-Ramelow "Frequency-modulated laser ranging sensor with closed-loop control", Proc. SPIE 10539, Photonic Instrumentation Engineering V, 1053909 (22 February 2018); https://doi.org/10.1117/12.2289585

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available