Fraunhofer-gesellschaft Zur Foerderung Der Angewandten Forschung E.v.

Aptiv Technologies Limited

Aptiv Technologies Ag

Roman J Dietz

Geng Fu

Denis Rainko

Thorsten Göbel

Chenghui Hao

Ali Haddadpour

Bernd Sartorius

Helmut Roehle

Mykhaylo Semtsiv

Björn Globisch

Ronald Melvin Taylor

Le Zheng

William Ted Masselink

Dennis Stanze

Michael DeLaus

W Ted Masselink

Chenghui F Hao

This document describes techniques and systems to alternate power-level scanning for ToF lidar systems. The described lidar system transmits an initial signal having a first power level of an alternating pattern of power levels. The initial signal is associated with an initial pixel of consecutive pixels. The lidar system then transmits a subsequent signal, which is associated with a subsequent pixel of the consecutive pixels, having a second power level. The transmission of the initial signal and the subsequent signal with the alternating pattern of power levels limits a total power level emitted by the lidar system during a time interval to comply with safety regulations. The alternating pattern of power levels also permits the lidar system to switch between a long-detection range and a short-detection range for consecutive pixels.

Alternating power-level scanning for time-of-flight lidar systems

This document describes techniques and systems to resolve return signals among pixels in lidar systems. The described lidar system transmits signals with different waveforms for consecutive pixels to associate return signals with their corresponding pixels. During a detection window, the lidar system receives a return signal and compares it in the frequency domain to at least two template signals. The template signals include the waveform of an initial pixel and a subsequent pixel of two consecutive pixels, respectively. The lidar system then determines, based on the comparison to the template signals, the pixel to which the return signal corresponds and determines a characteristic of an object that reflected the return signal. In this way, the lidar system can confidently resolve detections to reduce the time between pixels. This improvement allows the described lidar system to operate at faster scanning speeds and realize a faster reaction time for automotive applications.

Resolving return signals among pixels in frequency-modulated continuous-wave (FMCW) lidar systems

This document describes techniques and systems to increase the dynamic range of time-of-flight (ToF) lidar systems. The described lidar system adjusts, based on the energy of a first return pulse, the bias voltage of a photodetector for other return pulses of the object pixel. The bias voltage can be adjusted down for highly-reflective or close-range objects. Similarly, the bias voltage can be increased for low-reflectivity or long-range objects. The ability of the described lidar system to adjust the bias voltage of the photodetector for each object pixel increases the dynamic range of the lidar system without additional hardware or a complex readout. The increased dynamic range allows the described lidar system to maintain a long-range capability, while accurately measuring return-pulse intensity for detecting close-range or highly-reflective objects.

Increased dynamic range for time-of-flight (ToF) lidar systems

The techniques of this disclosure enable lidar systems to operate as fast-scanning FMCW lidar systems. The fast-scanning lidar system alternates chirp patterns frame by frame as a way to increase scanning speed, without adding additional hardware. Each consecutive pair of frames includes a frame with a long chirp pattern with multiple chirps and a frame with a short chirp pattern with as few as a single chirp, which is derived from the long chirp pattern assuming a constant object velocity between frames. The chirp pattern applied to each pixel is consistent within each frame but different from one frame to the next. The combined duration of two consecutive frames is less than the combined duration of two consecutive frames of a traditional FMCW lidar system that uses the same chirp pattern from one frame to the next. The shorter duration increases frame rate, scanning speed, or overall throughput of the fast-scanning lidar system.

Fast-scanning frequency-modulated continuous wave (FMCW) lidar systems

An illustrative example object detection system includes a sensor having a field of view. The sensor is configured to emit radiation and to detect at least some of the radiation reflected by an object within the field of view. A panel in the field of view allows the radiation to pass through the panel. The panel being is configured to be set in a fixed position relative to a vehicle coordinate system. A plurality of reflective alignment markers are situated on the panel in the field of view. The reflective alignment markers reflect radiation emitted by the sensor back toward the sensor. A processor is configured to determine an alignment of the sensor with the vehicle coordinate system based on an indication from the sensor regarding radiation reflected by the reflective alignment markers and detected by the sensor.

Object detection sensor alignment

A photoconductor for emitting and/or receiving electromagnetic waves is provided. The photoconductor comprises a material region comprising a first and a second section, wherein the second section provides a higher density of charge carrier trapping centers and/or recombination centers than the first section, and a confinement generating a sub-band structure of the charge carrier energy states in the material region. The first and the second section are arranged and configured in such a manner that a maximum of the carrier probability density of the sub-band ground state is located in one of these sections and a maximum of the carrier probability density of an excited sub-band state is located in the respective other section.

Photoconductor for emitting and/or receiving electromagnetic waves

A terahertz antenna includes at least one photoconductive layer which generates charge carriers upon irradiation of light and two electroconductive antenna elements via which an electric field can be applied to at least one section of the photoconductive layer. The photoconductive layer being doped with a dopant in a concentration of at least 1&#xd7;1018 cm&#x2212;3, the dopant being a transition metal. The photoconductive layer is produced by molecular beam epitaxy at a growth temperature of at least 200&#xb0; C. and not more than 500&#xb0; C., the dopant being arranged in the photoconductive layer such that it produces a plurality of point defects.

Terahertz antenna and method for producing a terahertz antenna

It is provided a system for determining characteristics of an object or a sample comprising at least a first and a second transmitter unit, wherein the first transmitter unit is configured for transmitting first electromagnetic waves towards the object and the second transmitter unit is configured for transmitting second electromagnetic waves towards the object; at least one receiver unit) for receiving electromagnetic waves from the object, the receiver unit generating a receiver signal upon receipt of the electromagnetic waves from the object. The first and the second transmitter unit is configured in such a way that the first and the second electromagnetic waves are modulated differently in such a way that by demodulating the receiver signal, a portion of the receiver signal evoked by the first electromagnetic waves can be separated from a portion of the receiver signal evoked by the second electromagnetic waves. The system comprises an evaluating unit.

System and method for determining characteristics of an object or a sample

The invention relates to a method for determining the relative temporal position of electromagnetic pulses. Said method having the steps generating a sequence of first electromagnetic pulses, generating a sequence of second electromagnetic pulses, overlaying at least a part of the first and the second pulses in a saturable absorber, detecting the second pulses that have passed through the saturable absorber by means of a detector in such a manner that the second pulses, but not the first pulses that have passed through the saturable absorber, are detected, and determining the temporal position of the first pulses relative to the temporal position of the second pulses with the aid of a signal from the detector which is generated when the second pulses that have passed through the saturable absorber are received.

Method for determining the relative temporal position of electromagnetic pulses and determination device

A terahertz system can be configured for producing and coherently detecting terahertz radiation. The system can comprise a laser light source and two THz antennas, a first of which is used as a transmission antenna and a second of which is used as a receiver antenna, which are each optically coupled to the laser light source by an optical fiber and can be activated by light from this laser light source, wherein the THz antennas each have a semiconductor chip to which antenna conductors have been contact-connected and which comprises at least one photosensitive active layer with a band edge wavelength which is longer than a wavelength of the laser light source and at least one layer, adjoining the active layer, with a band edge wavelength which is shorter than the wavelength of the laser light source, wherein the band edge wavelength of the active layer of at least one of the THz antennas is at least 200 nm longer than the wavelength of the laser light source.

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Berlin, Germany

Roman J Dietz