Eye-safe scanning lidar with virtual protective housing

An eye-safe light detection and ranging system includes a virtual protective housing. A short range pulse is emitted at every measurement point in a field of view before conditionally emitting a long range pulse. Short range pulses result in accessible emissions that are eye-safe at short distances and long range pulses result in accessible emissions that are eye-safe at longer distances.

FIELD

The present invention relates generally to light detection and ranging (LIDAR) systems, and more specifically to safety of LIDAR systems.

BACKGROUND

Products that include laser devices generally fall into different laser safety classes based on the possibility that they can cause damage to the human eye or skin. International Standard IEC 60825.1 describes example laser safety classes. Although many different laser safety classes exist, one major distinction between classes is whether a product is considered “eye-safe” or “non-eye-safe.” Eye-safe laser systems are generally considered to be incapable of producing damaging accessible radiation levels during operation, and are also generally exempt from device marking requirements, control measures, or other additional safety measures. IEC 60825.1 classifies eye-safe products as Class 1. Products that include high power laser devices that would otherwise be classified as non-eye-safe, may nevertheless be classified as eye-safe if the product includes additional safety measures such as a protective housing that reduces the accessible emission limits to a safe level.

DESCRIPTION OF EMBODIMENTS

FIG.1shows a scanning light detection and ranging (LIDAR) system with a virtual protective housing in accordance with various embodiments of the present invention. System100includes pulse generation circuit190, infrared (IR) laser light source130, scanning mirror assembly114with scanning mirror116, and mirror drive and control circuit154. System100also includes infrared (IR) detector142, time-of-flight (TOF) measurement circuit144, 3D point cloud storage circuit146, comparator148, and virtual protective housing circuit180.

Laser light source130may be a laser light source such as a laser diode or the like, capable of emitting a laser beam162. The beam162impinges on a scanning mirror assembly114which in some embodiments is part of a microelectromechanical system (MEMS) based scanner or the like, and reflects off of scanning mirror116to generate a controlled output beam134. In some embodiments, optical elements are included in the light path between light source130and mirror116. For example, system100may include collimating lenses, dichroic mirrors, or any other suitable optical elements.

A scanning mirror drive and control circuit154provides one or more drive signal(s)155to control the angular motion of scanning mirror116to cause output beam134to traverse a raster scan trajectory140in a field of view128. In operation, light source130produces modulated light pulses in the nonvisible spectrum and scanning mirror116reflects the light pulses as beam134traverses raster scan trajectory140.

In some embodiments, raster scan trajectory140is formed by combining a sinusoidal component on the horizontal axis and a sawtooth component on the vertical axis. In these embodiments, controlled output beam134sweeps back and forth left-to-right in a sinusoidal pattern, and sweeps vertically (top-to-bottom) in a sawtooth pattern with the display blanked during flyback (bottom-to-top).FIG.1shows the sinusoidal pattern as the beam sweeps vertically top-to-bottom, but does not show the flyback from bottom-to-top. In other embodiments, the vertical sweep is controlled with a triangular wave such that there is no flyback. In still further embodiments, the vertical sweep is sinusoidal. The various embodiments of the present invention are not limited by the waveforms used to control the vertical and horizontal sweep or the resulting raster pattern. The vertical axis is also referred to as the slow scan axis, and the horizontal axis is also referred to as the fast-scan axis. The labels “vertical” and “horizontal” are somewhat arbitrary, since a 90 degree rotation of the apparatus will switch the horizontal and vertical axes. Accordingly, the terms “vertical” and “horizontal” are not meant to be limiting.

Although scanning mirror116is shown as a single mirror that scans in two dimensions, this is not a limitation of the present invention. For example, in some embodiments, mirror116is replaced by two mirrors, one scanning in one dimension, and a second scanning in a second dimension. Further, although system100is described having one or more MEMS devices to perform scanning of laser light pulses, this is not a limitation of the present invention. Any device or method for scanning light pulses along a scan path may be employed without departing from the scope of the present invention.

In some embodiments, scanning mirror116includes one or more sensors to detect the angular position or angular extents of the mirror deflection (in one or both dimensions). For example, in some embodiments, scanning mirror assembly114includes a piezoresistive sensor that delivers a voltage that is proportional to the deflection of the mirror on the fast-scan axis. Further, in some embodiments, scanning mirror assembly114includes an additional piezoresistive sensor that delivers a voltage that is proportional to the deflection of the mirror on the slow-scan axis. The mirror position information is provided back to mirror drive and control circuit154as one or more SYNC signals115. In these embodiments, mirror drive and control circuit154includes one or more feedback loops to modify the drive signals in response to the measured angular deflection of the mirror. In addition, in some embodiments, mirror drive and control circuit154includes one or more phase lock loop circuits that estimate the instantaneous angular position of the scanning mirror based on the SYNC signals.

Mirror drive and control circuit154may be implemented using functional circuits such as phase lock loops (PLLs), filters, adders, multipliers, registers, processors, memory, and the like. Accordingly, mirror drive and control circuit154may be implemented in hardware, software, or in any combination. For example, in some embodiments, control circuit154is implemented in an application specific integrated circuit (ASIC). Further, in some embodiments, some of the faster data path control is performed in an ASIC and overall control is software programmable.

IR detector142includes one or more photosensitive devices capable of detecting reflections of IR laser light pulses. For example, IR detector142may include one or more PIN photodiodes, Silicon photomultipliers (SiPM), avalanche photodiodes (APD), or the like. Each point in the field of view that is illuminated with an IR laser light pulse (referred to herein as a “measurement point”) may or may not reflect some amount of the incident light back to IR detector142. If IR detector142detects a reflection, IR detector142provides a signal143to TOF measurement circuit144.

TOF measurement circuit144measure times-of-flight (TOF) of IR laser light pulses to determine distances to objects in the field of view. In some embodiments, virtual protective housing circuit180provides a timing signal (not shown) corresponding to the emission time of a particular IR laser light pulse to TOF measurement circuit144, and TOF measurement circuit144measures the TOF of IR laser light pulses by determining the elapsed time between the emission of the pulse and reception of the reflection of the same pulse.

TOF measurement circuit144may be implemented using any suitable circuits. For example, in some embodiments, TOF measurement circuit144includes an analog integrator that is reset when the IR pulse is launched, and is stopped when the reflected pulse is received. TOF measurement circuit144may also include an analog-to-digital converter to convert the analog integrator output to a digital value that corresponds to the time-of-flight (TOF) of the IR laser pulse, which in turn corresponds to the distance between system100and the object in the field of view from which the light pulse was reflected.

3D point cloud storage device146receives X, Y data from mirror drive and control circuit154, and receives distance (Z) data on node145from TOF measurement circuit144. A three-tuple (X,Y,Z) is written to 3D point cloud storage device for each detected reflection, resulting in a series of 3D points referred to herein as a “point cloud.” Not every X, Y measurement point in the field of view will necessarily have a corresponding Z measurement. Accordingly, the resulting point cloud may be sparse or may be dense. The amount of data included in the 3D point cloud is not a limitation of the present invention.

3D point cloud storage device146may be implemented using any suitable circuit structure. For example, in some embodiments, 3D point cloud storage device146is implemented in a dual port memory device that can be written on one port and read on a second port. In other embodiments, 3D point cloud storage device146is implemented as data structures in a general purpose memory device. In still further embodiments, 3D point cloud storage device146is implemented in an application specific integrated circuit (ASIC).

Comparator148compares the distance data (Z) on node145to a threshold value on node147, and if the distance is less than the threshold, then comparator148asserts the short range object detection signal on node184. The short range object detection signal alerts VPH circuit180to the detection of an object within a “short range,” where “short range” is determined by the value of the threshold on node147. For example, if the threshold is set to a value corresponding to a distance of five meters, and the detected distance is lower than that threshold, then an object closer than five meters has been detected, and VPH circuit180will be notified by the short range object detection signal on node184.

The threshold value on node147and the corresponding short range distance may be modified by VPH circuit184based on any criteria. For example, the threshold may be a function of IR laser pulse power, pulse duration, pulse density, wavelength, scanner speed, desired laser safety classification, and the like. The manner in which the threshold value is determined is not a limitation of the present invention.

VPH circuit180operates to manage accessible emission levels in a manner that allows overall operation to remain eye-safe. For example, in some embodiments, VPH circuit180controls whether a “short range pulse” or “long range pulse” is generated by setting a pulse energy value on node185. The emitted pulse energy may be controlled by one or more of pulse power, pulse duration, or pulse count.

VPH circuit180may also control the timing of emitted pulses via the timing signal on node157. In some embodiments, for every measurement point in the field of view, VPH circuit180signals pulse generation circuit190to generate a short range pulse that can detect objects with a very high level of confidence out to a distance sufficient to provide a virtual protective housing. As used herein, the term “short range pulse” refers to a pulse that is considered eye-safe at a very short range. For example, in some embodiments, the energy levels of the short range IR laser light pulses may be maintained below the IEC 60825.1 Class 1 Accessible Emissions Limit, such that short range IR laser light pulses can be emitted at every measurement point without risking injury to a human eye.

If an object is detected within the short range distance, the corresponding three-tuple (x,y,z) may be written to the 3D point cloud storage device146, and system100provides a virtual protective housing by not emitting any higher energy pulses at that measurement point. If, however, a short range object is not detected, system100may emit one or more “long range pulses” that are of higher total energy to detect objects beyond the short range distance. For example, in some embodiments, system100may emit a short range IR laser light pulse that is considered eye-safe at a distance of 100 millimeters (mm) that has a 50% probability of detecting a 5% reflective target at 36 meters (m) in bright sunlight. This short range pulse may have a one in 10 billion probability of not detecting a 10% reflective target at a distance of 12 m. Also for example, system100may emit a long range pulse capable of detecting objects up to 200 m distant while remaining eye-safe beyond four meters distance. In this example, system100may emit short range pulses that have an extremely high probability of detecting objects within four meters, and then emit long range pulses that are capable of detecting objects at 200 m.

As used herein, the term “long range pulse” refers to one or more pulses with higher total energy than short range pulses. For example, in some embodiments, a single long range pulse may be emitted, and the single long range pulse may have higher energy than a single short range pulse, and in other embodiments, multiple long range pulses may be emitted, and the total energy of the multiple long range pulses may be higher than the single short range pulse.

Virtual protective housing circuit180may be implemented using any suitable circuit structures. For example, in some embodiments, VPH circuit180may include one or more finite state machines implemented using digital logic to respond to short range object detection and conditionally signal pulse generation circuit190to emit long range pulses. Further, in some embodiments, VPH circuit180may include a processor and memory to provide software programmability of short range pulse energy, long range pulse energy, threshold values and the like. The manner in which VPH circuit180is implemented is not a limitation of the present invention.

FIG.2shows short and long range pulses in accordance with various embodiments of the present invention. Short range pulse210and long range pulses230are examples of IR laser light pulses that may be emitted by a LIDAR system at each measurement point. For example, LIDAR system100may emit short range pulse210and then conditionally emit one or more of long range pulses230based on whether a short range object is detected. Pulse amplitude is shown on the vertical axis and time is shown on the horizontal axis of the plot inFIG.2. Short range pulse210is shown being emitted at a first time and a threshold is shown representing a second time. The difference between the first and second times represents the short range distance. For example, in some embodiments, the threshold is set at approximately 33 nanoseconds (ns) corresponding to a short range distance of substantially five meters. In some embodiments, short range pulse210has an energy level that is considered eye-safe at a very short distance. For example, short range pulse210may be eye-safe at 100 mm from the LIDAR system from which it is emitted.

In some embodiments, if a short range object is detected, the LIDAR system does not emit any long range pulses for that measurement point, and the detected distance is written to the 3D point cloud. On the other hand, if a short range object is not detected, one or more long range pulses230is emitted in a manner that maintains accessible emissions at an eye-safe level. For example, short range pulse210may have an energy level that provides a very high probability of detecting an object within the short range distance, and long range pulse220may have a total energy level that is eye-safe at the short range distance and beyond. Long range pulses can follow shortly after the threshold time if no short range object is detected. For example, long range pulse220may be emitted within 100 ns of the threshold time, or at 133 ns. The times corresponding to the threshold and emission of long range pulses may be different in various embodiments based on the desired short range distance and processing times, and are not a limitation of the present invention.

In some embodiments, a single long range pulse220is emitted, and in other embodiments a train of long range pulses230is emitted for each measurement point. The number of long range pulses emitted at a single measurement point is not a limitation of the present invention. For example, in some embodiments, a single long range pulse may be emitted, where the single long range pulse has a higher energy than the short range pulse. Also for example, in some embodiments, multiple long range pulses may be emitted, and each long range pulse may have an energy level that is the same as the short range pulse, but the total energy of the multiple long range pulses is greater than the energy of the short range pulse.

Any number of pulses at any energy level may be employed to define multiple ranges. For example, a short range may be defined by the energy of a single short range pulse. Also for example, a medium range may be defined by multiple pulses, each having the same energy as the short range pulse, and a long range may be defined by one or more long range pulses with the same or greater energy as the short range pulse.

In some embodiments, a short range pulse is emitted at every measurement point, and in other embodiments, short range pulses are not emitted at every measurement point. For example, a short range pulse may be emitted at a first measurement point, and if a short range object is not detected, then long range pulses may be emitted at one or more subsequent measurement point without first emitting a short range pulse. This is possible in some embodiments, in part, because measurement points may be defined sufficiently close to one another to enable a valid assumption that when no short range object occupies a measurement point, no short range object occupies some number of subsequent measurement points.

FIG.3shows measurement points in a field of view in accordance with various embodiments of the present invention. Measurement points310are points on raster scan trajectory140at which the LIDAR system measures distance. For example, in some embodiments, a LIDAR system such as LIDAR system100(FIG.1) emits a short range pulse at each measurement point310to detect if an object is within the short range distance and then conditionally emit one or more long range pulses as described above.

The term “measurement point” as used herein, is not meant to designate an infinitely small point in space, but rather a small and finite continuous section of raster scan trajectory140. For example, the controlled output beam134(FIG.1) traverses a finite section of raster scan trajectory140during the round trip transit times of a short range pulse and long range pulse at each measurement point. The measurement point area is also a function of laser spot size (initial size and divergence) at the distance where it encounters an object. Accordingly, the “measurement point” encompasses an area, albeit very small, and the size and location of the area may be a function of many factors.

FIG.4shows a flow diagram of methods in accordance with various embodiments of the present invention. In some embodiments, method400, or portions thereof, is performed by a LIDAR system, embodiments of which are shown in previous figures. In other embodiments, method400is performed by a series of circuits or an electronic system. Method400is not limited by the particular type of apparatus performing the method. The various actions in method400may be performed in the order presented, or may be performed in a different order. Further, in some embodiments, some actions listed inFIG.4are omitted from method400.

Method400is shown beginning with block410in which a short range pulse energy level is set and the short range pulse is emitted. In some embodiments, this corresponds to setting a pulse energy level to a value that will result in eye-safe operation at a particular distance from the LIDAR system. For example, in some embodiments, a short range pulse energy level may be set by virtual protective housing circuit180(FIG.1) such that accessible emissions result in eye-safe operations at 100 mm, and in other embodiments, the pulse energy level may be set such that accessible emissions result in eye-safe operations at a minimum distance greater than 100 mm.

If a short range object is detected at420, then a 3D point (X,Y,Z) may be written to a 3D point cloud storage device such as 3D storage device146(FIG.1). If a short range object is not detected, then one or more long range pulses may be transmitted at440. As described above, short range object detection may be accomplished by detecting a reflection of the short rang pulse, measuring the time-of-flight of the detected reflection, and comparing that time-of-flight to a threshold. The value of the threshold corresponding to the short range distance may be set to any suitable value.

At430, one or more long range pulses are emitted. If an object is detected at440, then a 3D point (X,Y,Z) may be written to a 3D point cloud storage device such as 3D storage device146(FIG.1) and processing continues at the next measurement point at460. If an object is not detected, then processing continues at the next measurement point at460without writing a 3D point to the point cloud storage device.

FIG.5shows a probability of not detecting an object as a function of distance in accordance with various embodiments of the present invention. Probability curve510is a typical curve that may shift left or right based on many parameters including pulse energy level, reflectivity of the object, ambient light, etc. For example, in extremely bright sunlight, a short range pulse that is eye-safe at 100 mm may have 10-10 probability of not detecting an object with a 20% reflectivity at 20 m. This results in an even lower probability of not detecting an object at closer distances, so in this same scenario, a long range pulse that is eye-safe at 5 m provides a very robust virtual protective housing.

In some embodiments, the threshold corresponding to the short range distance and the energy level of the long range pulse(s) are set to values that result in the short range distance and the minimum eye-safe distance of the long range pulse(s) being equal. In other embodiments, the threshold corresponding to the short range distance and the energy level of the long range pulse(s) are set to values that result in the short range distance being greater than minimum eye-safe distance of the long range pulse(s).

FIG.6shows a moving platform with an eye-safe LIDAR system in accordance with various embodiments of the present invention. Automobile610is a platform upon which an eye-safe LIDAR system620is mounted. In some embodiments, eye-safe LIDAR system620is implemented using LIDAR system100(FIG.1) or any of the LIDAR systems discussed further below.

In some embodiments, the energy of short range pulses is increased when the platform upon which the LIDAR system is mounted is in motion. For example, when automobile610has a velocity above a threshold, the energy of short range pulses may have a level that results in accessible emissions eye-safe level at a minimum distance above 100 mm. In some embodiments, the minimum distance at which the accessible emissions result in eye-safe level may be a meter or more. Also for example, the energy of short range pulses may be increased with increased platform velocity. In some embodiments, the energy of short range pulses may be gradually increased as the platform accelerates between 2.5 meters per second (m/s) and 25 m/s.

Increasing the energy level of short range pulses may result in increased probability of detecting objects within the short range and/or increasing the short range within which objects can be detected.FIG.6shows an increased short range as a result of increased short range pulse energy.

FIG.7shows a flow diagram of methods in accordance with various embodiments of the present invention. In some embodiments, method410, or portions thereof, is performed by a LIDAR system, embodiments of which are shown in previous figures. In other embodiments, method410is performed by a series of circuits or an electronic system. For example, method410may be performed by a virtual protective housing circuit. Method410is not limited by the particular type of apparatus performing the method. The various actions in method410may be performed in the order presented, or may be performed in a different order. Further, in some embodiments, some actions listed inFIG.7are omitted from method410.

Method410corresponds to block410ofFIG.4. Method410is shown beginning with block710in which a default short range pulse energy level and a default time threshold are set. In some embodiments, the short range pulse energy level is set such that the accessible emissions are eye-safe at a short distance (e.g., 100 mm or less), and the time threshold is set to a value that provides a very low probability of not detecting an object (seeFIG.5).

At720, if a velocity is faster than a threshold, processing continues at740, and if a velocity is not faster than a threshold, processing continues at730. In some embodiments, the velocity corresponds to the velocity of a moving platform upon which the LIDAR system is mounted. For example, if the LIDAR system is mounted on an automobile, the velocity corresponds to the speed of the automobile. In some embodiments, the LIDAR system receives velocity information from the automobile, and in other embodiments, the LIDAR system includes a velocity sensor and does not rely on an external source of velocity information.

At740, the short range pulse energy level and the time threshold corresponding to the short range distance are increased. In some embodiments, the short range pulse energy is increased to a level that results in accessible emissions that result in eye-safe levels at a minimum distance of one meter. In other embodiments, the short range pulse energy is increased to a level that results in accessible emissions that result in eye-safe levels at a minimum distance greater than or less than one meter. At730, the short range pulse is emitted.

FIGS.8and9show scanning light detection and ranging (LIDAR) systems with a virtual protective housing and redundant detectors in accordance with various embodiments of the present invention.

Referring toFIG.8, LIDAR system800includes all of the components of LIDAR system100(FIG.1), and also includes a second IR detector842, second TOF circuit844, second comparator848, and OR gate880. In operation, the additional circuits provide a redundant short range object detection capability, and OR gate880will signal the detection of a short range object if either circuit detects a short range object.

Redundant short range object detection provides an additional measure of safety. For example, if one or the IR detectors, TOF circuits, or comparators should fail, the redundancy will ensure continued safe operation.

In some embodiments, IR detector142and second IR detector842receive reflected light through different optical paths. For example, IR detector142may receive reflected light along a path shown at135and IR detector835may share an optical path with the emitted light pulses. In embodiments represented byFIG.8, emitted IR laser light at162is reflected by mirror116to produce light pulses along path834, and any reflected light along path834will also be reflected by mirror116and reach IR detector842along path835.

In some embodiments, both of the detection and TOF circuits operate to detect short range objects, and only one of the detection and TOF circuits operate to measure long range distance and/or write to the 3D cloud storage device. For example, in embodiments represented byFIG.8, times-of-flight measured by either TOF circuit844or TOF circuit144may be used to detect a short range object, but only times-of-flight measured by TOF circuit144are used to populate the 3D point cloud.

Referring now toFIG.9, LIDAR system900includes VPH circuit184, pulse generation circuit190, 3D point cloud storage device146, OR gate880, and control circuit154. LIDAR system900also includes transmit module910, receive module930, TOF and short range detection circuits940, and TOF and short range circuits950.

Each of TOF and short range detection circuits940and950include a TOF circuit and comparator. For example, TOF and short range detection circuits940may include TOF circuit844and comparator848(FIG.8), and TOF and short range detection circuits950may include TOF circuit144and comparator148(FIG.8).

Transmit module910includes an IR laser light source to produce a pulsed laser beam, collimating and focusing optics, and one or more scanning mirror assemblies to scan the pulsed laser beam in two dimensions in the field of view. Transmit module910also includes an IR laser light detector that shares an optical path with emitted IR laser light pulses. Example embodiments of transmit modules are described more fully below with reference to later figures.

Receive module930includes optical devices and one or more scanning mirror assemblies to scan in two dimensions to direct reflected light from the field of view to an included IR light detector. Example embodiments of receive modules are described more fully below with reference to later figures.

Control circuit154controls the movement of scanning mirrors within transmit module910as described above with reference toFIG.1. Control circuit154also controls the movement of scanning mirrors within receive module930. In operation, control circuit140receives mirror position feedback information (not shown) from transmit module910, and also receives mirror position feedback information (not shown) from receive module930. The mirror position feedback information is used to phase lock the operation of the mirrors. Control circuit540drives microelectromechanical (MEMS) assemblies with scanning mirrors within transmit module910with drive signal(s)945and also drives MEMS assemblies with scanning mirrors within receive module930with drive signal(s)947that cause the mirrors to move through angular extents of mirror deflection that define the size and location of field of view128. The synchronization of transmit and receive scanning allows the receive aperture to only accept photons from the portion of the field of view where the transmitted energy was transmitted. This results in significant ambient light noise immunity.

As shown inFIG.9, the two dimensional scanning is performed in a first dimension (vertical, fast scan direction) and a second dimension (horizontal, slow scan direction). The labels “vertical” and “horizontal” are somewhat arbitrary, since a 90 degree rotation of the apparatus will switch the horizontal and vertical axes. As an example, the fast and slow scan directions are shown inFIG.9having a 90 degree rotation as compared to those shown inFIGS.1and8.

FIG.10shows a side view andFIG.11shows a top view of a transmit module in accordance with various embodiments of the present invention. Transmit module910includes laser light source1010, beam shaping optical devices1020, received energy pickoff device1060, mirror1062, beam shaping device1064, IR detector1066, scanner1028, and exit optical devices450.

In some embodiments, laser light source1010sources nonvisible light such as infrared (IR) light. In these embodiments, IR detector1066detects the same wavelength of nonvisible light, as does an IR detector in receive module930(FIG.9). For example, in some embodiments, light source1010may include a laser diode that produces infrared light with a wavelength of substantially 905 nanometers (nm), and IR detector1066detects reflected light pulses with a wavelength of substantially 905 nm. Also for example, in some embodiments, light source1010may include a laser diode that produces infrared light with a wavelength of substantially 940 nanometers (nm), and IR detector1066detects reflected light pulses with a wavelength of substantially 940 nm. The wavelength of light is not a limitation of the present invention. Any wavelength, visible or nonvisible, may be used without departing from the scope of the present invention.

Laser light source1010may include any number or type of emitter suitable to produce a pulsed laser beam. For example, in some embodiments, laser light source1010includes multiple laser diodes shown inFIG.11at1112,1114,1116, and1118. The pulsed laser light produced by laser light source1010is combined, collimated, and focused by beam shaping optical devices1020to produce a pulsed laser beam. For example, optical devices1022may collimate the laser beams on the fast axis, polarization rotators1023and beam combiners1020may combine laser beams, and optical devices1022may form the pulsed laser beam into a fan on the slow axis. Beam sizes and divergence values are not necessarily uniform across the various embodiments of the present invention; some embodiments have higher values, and some embodiments have lower values.

Scanner1028receives the pulsed laser beam from optical devices1020and scans the pulsed beam in two dimensions. In embodiments represented byFIGS.10and11, scanner1028includes two separate scanning mirror assemblies1030,1040, each including a scanning mirror1032,1042, where each scanning mirror scans the beam in one dimension. For example, scanning mirror1032scans the pulsed beam in the fast scan direction, and scanning mirror1042scans the pulsed beam in the slow scan direction.

Although scanner1028is shown including two scanning mirror assemblies, where each scans in a separate dimension, this is not a limitation of the present invention. For example, in some embodiments, scanner1028is implemented using a single biaxial scanning mirror assembly that scans in two dimensions. In some embodiments, scanning devices uses electromagnetic actuation, achieved using a miniature assembly containing a MEMS die and small subassemblies of permanent magnets and an electrical interface, although the various embodiments are not limited in this respect.

Exit optical devices1050operate on the scanning pulsed laser beam as it leaves the transmit module. In some embodiments, exit optical devices1050perform field expansion. For example, scanning mirror assembly1028may scan through maximum angular extents of 20 degrees on the fast scan axis, and may scan through maximum angular extents of 40 degrees on the slow scan axis, and exit optical devices1050may expand the field of view to 30 degrees on the fast scan axis and 120 degrees on the slow scan axis. The relationship between scan angles of scanning mirrors and the amount of field expansion provided by exit optical devices1050is not a limitation of the present invention.

Received energy pickoff device1060deflects received light (shown as a dotted line) that shares the transmit optical path with the emitted light pulses (shown as a solid line). The deflected received light is then reflected by mirror1062, focused by optical device1064, and detected by IR detector1066. In some embodiments, pickoff device1060includes a “window” that transmits the pulsed beam produced by the IR laser light source, and a reflective outer portion to deflect received energy outside the window. In other embodiments, pickoff device1060is a partial reflector that transmits a portion of incident light and reflects the rest. For example, a reflector that transmits 90% of incident light and reflects 10% of incident light will provide the IR detector with 10% of the light reflected off an object in the field of view. In still further embodiments, pickoff device1060may incorporate a polarizing beam splitter that transmits the pulsed laser beam (at a first polarization), and picks off received light of a different polarization. This is effective, in part, due to the reflections being randomly polarized due to Lambertian reflection. In still further embodiments, the outgoing laser beam and received energy may be directed to different portions of the scanning mirrors, and pickoff device1060may be an offset mirror positioned to reflect one but not the other.

IR detector1066may be an example embodiment of IR detector842(FIG.8). For example, in some embodiments, transmit module930implements the transmit side (with redundant IR detector) of LIDAR system800.

FIG.12shows a side view andFIG.13shows a top view of a receive module in accordance with various embodiments of the present invention. Receive module930includes IR detector1210, fold mirrors1212, imaging optical devices1220, bandpass filter1222, scanner1228, and exit optical devices1250.

Scanning mirror assemblies1230and1240are similar or identical to scanning mirror assemblies1030and1040, and exit optical devices1250are similar or identical to exit optical devices1050. Bandpass filter1222passes the wavelength of light that is produced by laser light source1010, and blocks ambient light of other wavelengths. For example, in some embodiments, the laser light source produces light at 905 nm, and bandpass filter1222passes light at 905 nm.

Imaging optical devices1220image a portion of the field of view onto IR detector1210after reflection by fold mirrors1212. Because scanner1228is scanned synchronously with scanner1028, arrayed receiver1210always collects light from the measurement points illuminated by the scanned pulsed beam.

FIG.14shows a cross sectional top view of an integrated photonics module in accordance with various embodiments of the present invention.

Integrated photonics module1410includes both transmit module910and receive module930. In some embodiments, a photonics module include transmit module910, and a receive module that does not include a separate scanning assembly. For example, a photonics module may implement the optical portions of LIDAR system800(FIG.8) which includes a scanner on the transmit side that shares an optical path with an IR detector, and includes a receiver side without a separate scanner.

FIG.15shows a perspective view of the integrated photonics module ofFIG.14. Integrated photonics module1410is shown having a rectangular housing with transmit module910and receive module930placed side by side. In some embodiments, transmit module910and receive module930are placed one on top of the other. The relative orientation of transmit module910and receive module930is not a limitation of the present invention.

FIG.16shows a scanning projector with an eye-safe LIDAR system in accordance with various embodiments of the present invention. Scanning projector1600includes all of the components shown inFIG.1and also includes image processing component1602, power control circuit1604, and visible laser light source1630. In some embodiments, visible laser light source includes red, green, and blue laser light sources that are pulsed to create visible pixels that result in a viewable image in field of view128.

Power control circuit1604is responsive to VPH circuit184to reduce power of visible laser light pulses when objects are detected in the field of view. For example, if a short range object is detected, power control circuit1604may blank the visible laser light or reduce power levels such that accessible emissions are eye-safe at the distance of the detected object.

FIG.17shows an interactive display device in accordance with various embodiments of the present invention. Interactive display device1700includes scanning projector1600, which in turn includes laser light sources1630,130and IR detector142. In some embodiments, interactive display device displays visible content and a user may interact through gesture recognition.

FIG.18shows a short throw projector in accordance with various embodiments of the present invention. Short throw projector1800is positioned on a shelf1810and projecting into field of view1880onto a wall1720. Projector1800includes any virtual protective housing circuits described above.