Despite the relatively high implementation costs and the complexity of the system, Frequency-modulated Continuouswave Light Detection and Ranging (FMCW LIDAR) has attracted special attention as the next generation LIDAR because generally existing LIDARs using pulse or amplitude modulation have limitation for high-resolution and interference phenomenon. Bandwidth and its linearity of the optical wavelength modulation in FMCW LIDAR have remarkable effects on spatial and range resolution including detection range. Hence, most FMCW LIDAR systems need to linearize the optical frequency sweep for best performance. However, since the linearization techniques normally require high-cost and complex systems, its adoption can be restricted in some application fields where low-cost and simple architecture are important. In this paper, measurement and analysis results for high-resolution of low-cost FMCW LIDAR using non-linear sweep characteristics of different lasers were presented. DFB laser and VCSEL of wavelengths near 1550 nm were utilized in these experiments, and the optical frequency sweep and beat frequency characteristics of each laser were analyzed in detail. The problem of low spectral resolution that occurs due to sweep nonlinearity was improved by the partial-waveform technique. Furthermore, by means of the beat frequency distribution which was obtained from repeat measurement and spline interpolation, the detailed analysis of beat frequency stability and distance resolution for various modulation frequencies were presented. Finally, using the multi-peak-averaging (MPA) method which efficiently utilizes high modulation frequency to improve the distance resolution, it is possible to achieve um-level range detection accuracy in the implemented FMCW system based on the uncompensated FMCW sources.
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