i Abstract This work relates to the field of distance measurement, more precisely to optical distance measurement with a laser rangefinder. Laser rangefinders are electrooptical measurement devices for measuring the distance to an object. The nonmilitary target application in this work is measuring distances on a construction site. The target distance ranges from few centimeters to tens of meters. Millimeter distance accuracy is required. A further constraint that has to be met is a low overall

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... system cost. Construction or DIY (do it yourself) applications are a very price sensitive market; hence the overall system cost should be as low as possible. Achievements ii Achievements In this work, we study a laser rangefinder using a low-cost photon counter. The goal is measuring distances with millimeter precision over a target distance ranging from a few centimeters to tens of meters. Single-photon avalanche diodes (SPADs) or at least the basic underlying effects are well-known since the 1960s. However, only recently first devices have been demonstrated in a CMOS technology, which known to be suitable for large-scale manufacturing of cellphone cameras. Because this type of photodetector is CMOS-compatible, it can be co-integrated with further circuitry, which promises a low overall system cost. In the following, the main achievements of this work are summarized. Single-photon Avalanche Diodes Characterization of SPAD Parameters: We study the performance parameters of single-photon avalanche diodes (SPADs), in particular the photon detection efficiency (PDE), the dark count rate (DCR), the dead time, afterpulsing and time jitter. Various device variations are provided by our technology partner STMicroelectronics in a 130 nm imaging technology. Several parameters are characterized over an array of 3×3 SPADs in a first wafer run and over an array of 6×10 SPADs in a second wafer run. Achievements iii quenching is increased from 11.9 MHz with negative-drive option to 45.6 MHz with positive-drive option. SPAD Parameters for Laser Rangefinder: In the course of this work, we identify several SPAD parameters of particular relevance for a ranging system. While the dark count rate and afterpulsing should be as low as possible for certain laboratory measurements, these parameters are less important for a laser rangefinder. In a SPAD-based laser rangefinder, however, any influence that affects SPAD timing, i.e., the time between photon incidence and an electrical pulse at the output, is crucial. Moreover, a high stability of the temporal behavior versus device mismatch, temperature, and voltage is of utmost importance. System Aspects of a Laser Rangefinder Performance Estimation: We model the performance of a single-spot, SPAD-based laser rangefinder with a fixed-focus optical system. An optical analysis determines the expected light levels on the detector plane, including background light and signal light that is scattered back from the target. Experimentally determined SPAD parameters from the previous section are taken into account. Distance measurement is based on frequency-domain reflectometry, which is also referred to as single-photon synchronous detection (SPSD) when using SPAD detectors. To achieve millimeterprecision distance measurements, a modulation frequency of about 400 MHz to 1.1 GHz is required. A Monte Carlo simulation estimates non-idealities of the so-called "binning architecture" (an architecture for sampling windows in time) for evaluating the received backscattered signal. Bin Homogenization: For sampling and evaluating the signal that is backscattered form the target, we propose a so-called "bin homogenization" scheme to mitigate non-idealities of the sampling windows of the binning architecture without prior calibration. The semiconductor process used for the fabrication of SPADs is optimized for optical properties, however, it suffers from severe RF-limitations. Nevertheless, an RF modulation frequency is required to achieve millimeter precision. A high-speed oscillator to drive a clocked shift-register to generate the sampling windows for sampling the incident signal is not available in this technology. Instead, we derive the individual sampling windows (bins) from the delay stages of a voltage-controlled oscillator. Because of non-ideal matching of the delay Achievements iv stages, the derived bins (sampling windows) have unequal bin widths that must be compensated for. State-of-the-art measurement schemes would require calibration for each device before each new measurement series. We overcome this limitation with the proposed bin homogenization scheme (patent-pending). Laser Rangefinder ASIC: We combine SPADs, timing-circuitry and a laser modulator into a system-on-chip laser rangefinder ASIC. Our first multiproject wafer (MPW2009) comprises the first system-on-chip laser rangefinder including a 3×3 SPAD array, timing-circuitry and a laser driver on a single ASIC. Our second multi-project wafer (MPW2011) comprises a 6×10 SPAD array and several improvements to building blocks. Most importantly, it successfully demonstrates the proposed bin homogenization scheme. Both chips are designed and implemented by our technology partners Bosch Automotive Electronics and STMicroelectronics. Laser Rangefinder Prototype: We successfully build a laser rangefinder prototype based on the laser rangefinder ASIC including SPADs. Under ideal laboratory conditions and with the proposed bin homogenization scheme, the laser rangefinder prototype reaches a maximum distance error as low as 0.24 mm for a target distance of up to 3.2 m, even with unavoidable noise and systematic errors. To the best of our knowledge, we achieved the highest accuracy for a SPAD-based ranging system so far. Zusammenfassung (German Abstract) v Zusammenfassung (German Abstract) Die vorliegende Arbeit befasst sich mit einem Laser-Messgerät zur Entfernungsmessung. Aus militärischen Anwendungen sind Laser-Entfernungsmessgeräte insbesondere zur Zielerfassung bekannt. Die vorliegende Arbeit befasst sich jedoch mit der zivilen Nutzung handlicher Laser-Entfernungsmessgeräte für Heimwerker, Handwerker und zum Einsatz auf Baustellen. Typische Zielentfernungen liegt im Bereich von wenigen Zentimetern bis zu einigen zehn Metern. Hierbei ist insbesondere bei kurzen Entfernungen eine Messgenauigkeit im Millimeterbereich erforderlich. Eine für den wirtschaftlichen Erfolg entscheidende Randbedingung sind geringe Kosten, da preissensible Märkte bedient werden sollen. Zusammenfassung (German Abstract) vi Probleme, welche bei hochaufgelöster Abtastung einem integrierten System mit SPADs und Zeitmess-Elektronik auf einem Chip innewohnen. Eine theoretische Performance-Abschätzung simuliert die Leistungsfähigkeit des vorgeschlagenen SPAD-basierten Laser-Entfernungsmessgeräts bei verschiedenen Messbedingungen. Versuche im Labor sowie erfolgreiche Tests mit einem Prototyp eines Laser-Entfernungsmessgeräts runden diese Arbeit ab. Der Prototyp erreicht die Zielvorgabe: Entfernungsmessung mit Millimeter-Genauigkeit. Das demonstrierte SPAD-basierte Laser-Entfernungsmessgerät übertrifft ein konventionelles APD-basiertes System in Bezug auf Kostengünstigkeit, Handlichkeit der Abmessungen und Fertigungsfreundlichkeit. Die Messgenauigkeit erfüllt die Anforderungen der relevanten Mess-Szenarien für Handwerk und Heimwerk.