Towards a Multi-Perspective Time of Flight Laser Ranging Device Based on Mirrors and Prisms

Abstract

This paper investigates the feasibility of redirecting the field of view (FOV) of a light-based time-of-flight (ToF) ranging device, commonly known as a pulsed lidar, using fixed mirrors and prisms for possible future use in robotics. The emphasis is on configurations where the FOV redirection element is positioned beyond the ranging device’s dead zone. A custom made direct ToF ranging device with time-over-threshold (TOT)-based walk error compensation was used to evaluate the effects of the FOV redirecting optics on range measurement accuracy and precision. The tests include redirecting the FOV with a clean prism with anti-reflective (AR) coating on its legs, as well as with a regular and a first surface mirror in both a clean and dusted state. The study finds the prism to be unsuitable due to parasitic reflections, which ruin the ranging data. The clean mirrors were found to have no noticeable effect on ranging accuracy. When they are dusty, mirrors introduce a negative measurement error. This effect is the most pronounced when a mirror is positioned toward the end of the partial dead zone of the ToF rangefinder, but loses influence as the mirror is moved farther away. The error is attributed to the parasitic reflection off dust on the mirror, which reduces the time of detection of the pulse reflected off the real target, and interferes with the walk error compensation by widening the detected pulse.

Modular Lidar System for Multiple Field-of-View Ranging

“…Furthermore, it does not offer much insight into the reflected light properties. Building off our previously designed lidar [ 21 ], a novel direct ToF modular lidar system with a centralized processing and power supply, and up to sixteen daughter boards that each comprise a laser diode, an avalanche photodiode (APD), and a time to digital converter (TDC) has been designed. A simplified schematic is presented in Figure 3 .…”

“…Examples include using stationary mirrors to simulate observing an object with multiple 3D cameras [ 17 ] and using mirrors, mounted onto a robot, to expand the field of view (FOV) of a scanning lidar [ 18 , 19 , 20 ]. Furthermore, we explored the effect of mirrors on the measurement accuracy and precision in our last article [ 21 ]. With this information, a method of distributing FOVs using mirrors can be proposed.…”

Multi-Sensor Laser System for Electric Guitar Pitch-Detection

“…In addressing the specified requirements, one potential avenue worth exploring involves the utilization of a time-of-flight measurement system [2][3][4][5], employing either pulsed or continuous-wave lasers. However, this approach, commonly employed for When a guitar is played, the player's fingers come into play by shortening the distance between the string and the fingerboard through the act of pressing.…”

“…In addressing the specified requirements, one potential avenue worth exploring involves the utilization of a time-of-flight measurement system [2][3][4][5], employing either pulsed or continuous-wave lasers. However, this approach, commonly employed for long-distance measurements, proves unsuitable in the present context due to its inherent limitations in resolution and high associated costs.…”

Special Issue on Trends and Challenges in Robotic Applications

“…Similarly, [18] presents an interesting approach to pose computation using a 3D reconstruction of data obtained using an RGB-D multi-camera. A groundbreaking piece of technology that is currently attracting attention due to its relatively low cost is Time-of-Flight (ToF) sensing, and the authors of [19] present a multi-perspective ToF laser ranging system using prisms and mirrors.…”