Control modules for laser systems having auto-ranging and control capability

Control modules for automatically adjusting a laser output based on a range to an object detected within a field of view are disclosed.

FIELD OF THE INVENTION

The present disclosure is directed to laser control systems, and more particularly, to control modules for automatically adjusting a laser output based on a range to an object detected within a field of view.

BACKGROUND OF THE INVENTION

Laser systems are used in a wide variety of civilian and military applications. Laser systems may be used, for example, for illuminating objects, determining distances (or ranging), detecting events, targeting objects, communications, and for a wide variety of other purposes. Recently, high-intensity laser illumination (or “dazzling”) has been used in various security-related applications (e.g. military checkpoints, border crossings, access control stations, etc.) and has proven to be an effective deterrent of potentially-hostile activity, thereby promoting stability and saving lives.

As is generally known, laser systems are not entirely without risk to human vision. Many applications require laser systems to be operated at power levels that may be considered detrimental to human vision. One generally-accepted criterion for assessing whether a laser is operating at a power level detrimental to human vision is known as the Nominal Ocular Hazard Distance (NOHD). Because a power density of a laser's output decreases with increasing distance from the laser due to beam spreading, a particular laser power level may be considered safe at longer ranges, but may become hazardous within a certain operating range near the laser. The NOHD defines a near-range exposure danger zone for human vision.

In many situations that involve relatively high power laser systems, protection protocols and systems have been developed that attempt to minimize harmful exposure to laser irradiation that may be detrimental to human vision. Such protocols and systems may include, for example, mandatory use of laser-safe goggles, laser beam enclosures (particularly within the NOHD), door-lock systems that automatically shut off laser systems upon entry, and various other safety measures. Although desirable results have been achieved, there are situations where the use of such conventional safety systems and protocols may be impractical or impossible.

SUMMARY

The present disclosure teaches control modules for automatically adjusting a laser output (e.g. intensity, output power, etc.) based on a range to an object detected within a field of view to reduce a potential risk to the object. Embodiments of systems and methods in accordance with the teachings of the present disclosure may advantageously enhance the safety of laser operations in a variety of conditions and circumstances where conventional safety methods and protocols are impractical or impossible to implement.

For example, in one embodiment, a control module assembly for adjusting an output of a laser includes an emitter configured to emit a ranging beam toward a target; a detector configured to receive a reflected beam from the target; and a control module operable to communicate with the emitter and the detector to determine a distance to the target, to determine a reference distance based on one or more operating conditions of the laser, to compare the distance to the target with the reference distance, and based on the comparison to provide a control signal to controllably adjust one or more aspects of the laser output to provide an improved comparison between the distance to the target and the reference distance.

Similarly, in another embodiment, a method for adjusting an output of a laser includes emitting a ranging beam toward a target; receiving a reflected beam from the target; determining a distance to the target; determining a reference distance based on one or more operating conditions of the laser; comparing the distance to the target with the reference distance; and based on the comparison, controllably adjusting one or more aspects of the operating conditions of the laser to provide an improved comparison between the distance to the target and the reference distance.

DETAILED DESCRIPTION

The present disclosure is directed to laser systems and methods having an ability to automatically adjust a laser output based on a range to an object detected within a field of view. Many specific details of certain embodiments in accordance with the present disclosure are set forth in the following description and inFIGS. 1-11to provide a thorough understanding of such embodiments. One skilled in the art, however, will understand that the present invention may have additional embodiments, or that the invention may be practiced without several of the details described in the following description.

FIG. 1is an exemplary environment100having a laser system110in accordance with an embodiment of the present disclosure. In a first operating condition103, the laser system110directs a laser beam120along a beam axis122toward a target102. The laser beam120may be a pulsed or non-pulsed laser beam120. As depicted by the gradually-decreasing shading of the laser beam120, an intensity (or power density) of the laser beam120generally decreases with increasing distance from the laser system110(e.g. due to beam spreading, absorption, etc.). At least part of the laser beam120that impinges on the target102is reflected as target reflections124(specular or non-specular) from the target102. In the first operating condition103, an intermediate object104(e.g. a bystander) is positioned generally outside of the laser beam120.

Although the exemplary environment100shown inFIG. 1depicts the target102as a vehicle, it will be appreciated that in alternate embodiments, the target102may be any type of object (military or civilian) that may be illuminated with the laser system110, including a person, a building, a natural landscape, a watercraft, an aircraft, or any other suitable object. Similarly, the laser beam120may be configured for a variety of purposes, including, for example, to illuminate the target102, to “dazzle” the target102(or occupants thereof), for targeting or aiming a weapon system (not shown), for inflicting damage on the target102, or for any other suitable purpose.

In the embodiment shown inFIG. 1, the laser system110includes a laser source112and a beam directing assembly114that cooperatively generate and condition the laser light that ultimately forms the laser beam120. A ranging system150is configured to determine a distance (or range) DTto the target102. A control system116is configured to transmit control signals to one or more of the other components of the laser system110, including the laser source112and the beam directing assembly114. The control system116is also configured to receive signals from one or more of the other components of the laser system110, including the ranging system150. In some embodiments, the laser system110also includes a power source118(e.g. a battery), such as may be desired for a portable laser system, however, in alternate embodiments, the laser system110may rely on an external power source (not shown).

The ranging system150may be based on a variety of conventional ranging methods and techniques. For example, in some embodiments, the ranging system150may be configured to receive at least a portion of the target reflections124from the target102, and may include a time-of-flight (TOF) system that clocks the time required for a portion of the laser beam120(e.g. a laser pulse) emitted by the laser system110to travel to the target102, reflect from the target102, and travel back to the ranging system150, given by:
Time=(2DT/cair)=6.681 nsec/m  (1)
where cairis the speed of light through air, and DTis a distance between the laser system110and the target102(or target distance). Thus, the target distance DTmay be determined by:
DT=(Timecair)/2=0.1497 m/nsec  (2)

In alternate embodiments, the ranging system150may be based on other suitable ranging methods, including triangulation, modulation, or any other ranging technologies. In further embodiments, the ranging system150need not be based on any portion of the laser beam120(e.g. a laser pulse), but rather, may be independent from the laser beam120. For example, in some embodiments, the ranging system150may be based on sonic (or acoustic) signals, ultrasonic signals, non-laser light signals, including signals from any suitable portion of the electromagnetic spectrum, imaging technologies, or even various non-signal-based technologies for determining range and distance (e.g. Global Positioning System technologies, physical contact sensors, etc.). Representative examples of suitable ranging technologies that may be used by the ranging system150include, but are not limited to, those technologies generally described in U.S. Pat. No. 7,317,872 issued to Posa et al., U.S. Pat. No. 7,271,761 issued to Natsume et al., U.S. Pat. No. 7,075,625 issued to Abe, U.S. Pat. No. 7,154,591 issued to Muenter, U.S. Pat. No. 6,697,146 issued to Shima, and U.S. Pat. No. 5,336,899 issued to Nettleton et al.

With continued reference toFIG. 1, a standoff distance DSis shown. The standoff distance DSmay depend on various factors of the environment100, such as the operating conditions and purpose of the laser beam120, the range and identity of the target102, the presence and identity of the bystander104, or any other factors. In some embodiments, for example, the standoff distance DSmay be based on a desire to avoid a potential hazard to human vision. More specifically, the standoff distance DSmay be approximately equal to (or based on) a Nominal Ocular Hazard Distance (NOHD). Of course, in alternate embodiments, other criterion for establishing the standoff distance DSmay be used.

In some embodiments, operation of the laser system110may begin by activating the laser system110to provide the laser beam120directed toward the target102to perform the desired functionality. The standoff distance DSmay be established by the operating conditions of the laser system110, and may initially be assumed to compare favorably with the target distance DT. The ranging system150may then determine the target distance DT, either simultaneously or sequentially with the generation of the laser beam120.

The laser system110may then compare the target distance DTwith the standoff distance DS(e.g. using the control system116). If the target distance DTcompares favorably with the standoff distance DS(e.g. target distance DTexceeds standoff distance DS), the laser system110may continue providing the laser beam120without making any adjustments to the laser system110. Alternately, if the target distance DTcompares unfavorably with the standoff distance DS(e.g. target distance DTdoes not exceed standoff distance DS), the laser system110may perform adjustments to the operating conditions of the laser system110(and thus the standoff distance DS) until a favorable comparison is achieved.

More specifically, in some embodiments, the laser system110(e.g. using the control system116) may controllably adjust one or more portions of the laser system110to adjust the laser beam120, and thus the standoff distance DS, until the target distance DTmeets or exceeds the standoff distance DS. For example, the control system116may adjust an output power of the laser source112, or one or more portions of the beam directing assembly114(e.g. beam conditioning optics, attenuators, etc.), or both the laser source112and the beam directing assembly114, to adjust the standoff distance DS. In further embodiments, other portions of the laser system110may be adjusted to provide a desired standoff distance DS. As operations continue, the laser system110may continue to monitor the target distance DT, and continue to controllably adjust the laser operating conditions so that the standoff distance DScontinues to compare favorably with the target distance DT.

In some embodiments, the laser system110may begin operating in a different way. More specifically, the operation of the laser system110may begin by having the ranging system150determine the target distance DT(e.g. by “pinging” the target102). Based on the target distance DT, the laser system110may initiate the laser beam120so that the target distance DTcompares favorably with the standoff distance DS. For example, in some embodiments, the standoff distance DSmay be established based on a desire to avoid potential hazards to human vision. In such cases, the standoff distance DSmay be based on the NOHD, and the laser system110may controllably generate the laser beam120so that the standoff distance DSis less than (or equal to) the target distance DT.

In still other embodiments, the operating conditions may be set so that the standoff distance DSmay initially assume a reasonably small value. The laser system110may then be operated to generate and direct the laser beam120toward the target102, and the ranging system150may be operated, either simultaneously or sequentially with the presence of the laser beam120, to determine the target distance DT. The laser system110(e.g. via the control system116) may determine whether the target distance DTcompares favorably or unfavorably with the standoff distance DS, and may perform adjustments to laser beam120accordingly.

FIG. 2shows the laser system110in a second operating condition105wherein the intermediate object (or bystander)104has recently moved into the laser beam120. In the second operating condition105, at least part of the laser beam120that impinges on the intermediate object104is reflected as intermediate reflections126. The ranging system150automatically determines an intermediate distance DIbetween the laser system110and the intermediate object104, and the control system110compares the intermediate distance DIwith the standoff distance DS. In the second operating condition105shown inFIG. 2, the intermediate distance DIis less than the standoff distance DS, and thus compares unfavorably with the standoff distance DS. More specifically, in some embodiments, the bystander104has entered the NOHD portion of the laser beam120(i.e. the near-range exposure danger zone for human vision).

In a third operating condition107shown inFIG. 3, the laser system110has automatically adjusted the standoff distance DSbased on the presence of the intermediate object104. More specifically, the laser system110has automatically adjusted one or more portions of the laser system110to provide an adjusted laser beam130such that the intermediate distance DImeets or exceeds the standoff distance DS. Although the third operating condition107shown inFIG. 3depicts that laser system110as providing the adjusted laser beam130, it will be appreciated that in some embodiments, it may be necessary to completely shut down the laser system110in the third operating condition107so that the intermediate distance DIcompares favorably with the standoff distance DS.

In a fourth operating condition109shown inFIG. 4, the bystander104has moved out of the laser beam130. The ranging system150automatically determines that the bystander104is no longer within the laser beam130(or other specified field-of-view), and that the closest object within the laser beam130is once again the target102. Based on the target distance DT, the laser system110automatically adjusts the laser beam120(and thus the standoff distance DS) back to the initial operating condition103. In the fourth operating condition109, the laser system110continues to provide the laser beam120to perform the desired function, and may continue to monitor and adjust the operating conditions so that the target distance DTcompares favorably with the standoff distance DS.

Embodiments of systems and methods in accordance with the present disclosure may provide substantial advantages over conventional laser systems. For example, systems and methods having an ability to automatically adjust a laser output based on a range to an object detected within a field of view may promote safety in a wider range of operating environments in comparison with conventional systems. Because such systems may automatically detect the presence of an intermediate object, and may automatically adjust the laser system to ensure that the intermediate object is outside the standoff distance, embodiments in accordance with the present disclosure may enhance the safety of laser operations in a variety of conditions and circumstances where conventional safety methods and protocols are impractical or impossible to implement. Embodiments in accordance with the present disclosure may also enhance the safety of laser operations at substantially-reduced cost, and with improved reliability, in comparison with conventional alternatives.

It will be appreciated that a variety of suitable embodiments of the laser system110may be conceived that provide the desired operability in accordance with the teachings of the present disclosure. For example,FIG. 5is a schematic view of one possible embodiment of the laser system110ofFIG. 1. In this embodiment, the laser source112includes a pulse generator160coupled to a laser driver162. A laser diode164is driven by the laser driver162to provide a laser light166to the beam directing assembly114. One or more conditioning optics168of the beam directing assembly114condition the laser light166to provide a collimated laser beam along the beam axis122.

In some implementations, the components of the laser system110may be configured to provide a pulsed laser light166at controlled current levels. For example, the pulses of laser light166may be adjustably varied within a range of approximately 10 nsec to approximately 50 nsec. Of course, in alternate embodiments, pulses of any other suitable duration may be employed.

With continued reference toFIG. 5, in this embodiment, the ranging system150receives a reflected portion172of the emitted laser beam that reflects from the distal target102or the intermediate object104. The reflected portion172passes through an optical bandpass filter174and one or more conditioning optics176of the ranging system150before impinging upon a detector178. In some embodiments, the detector178may include a photodiode, an avalanche photodiode, a photo-detector, or any other suitable detection device. Output signals from the detector178may be conditioned by an amplifier180and by an automatic gain control (AGC) component182. The AGC component182conditions the output signals so that, despite variations in the input level (e.g. the reflected portion172), the average level of the output from the AGC component182are approximately at a predetermined value (or within a predetermined range). A timer (or counter)184receives the output signals from the AGC component182and determines the target distance DTusing, for example, Equation (2) above.

FIG. 6is an exemplary laser power time history200of the laser system110ofFIG. 5. In this embodiment, the time history200includes a series of alternating illumination pulses202and ranging pulses204. The ranging pulses204are of higher intensity and shorter duration than the illumination pulses202, and are configured to operate as the source of the reflected signals172received by the ranging system150. Similarly, the illumination pulses202are configured to perform the intended purpose of the laser system110with respect to the target102(e.g. illuminate, “dazzle,” aim, damage, etc.).

FIG. 7is a schematic view of a system300in accordance with another alternate embodiment of the present disclosure. In this embodiment, the system300includes a laser component310and a ranging component350powered by an external power source305. The laser component310includes a laser source112and a beam directing assembly114having substantially the same structural components and functionality as described above with respect toFIG. 5. A controller320controls the laser source112and the beam directing assembly114to provide a laser output122toward a distal target (not shown).

The ranging component350is operatively coupled to the laser component310and includes a signal generation portion360, a signal detection portion370, and a distance determination portion380. In this embodiment, the signal generation portion360includes a source362that emits signals364into a signal conditioner366. A ranging signal368is transmitted from the signal generation portion360toward a distal object within a field of view of the ranging component350.

As further shown inFIG. 7, a portion of the ranging signal368is reflected back from the distal object as a return signal372. The return signal372passes through a first signal conditioner374(e.g. a filter), a second signal conditioner376(e.g. focusing optics), and arrives to a detector378. The distance determination portion380receives an output from at least the signal detection portion370and determines the range to the distal object. The ranging component350outputs the range to the laser component310(e.g. to the controller320), and continues performing ranging of distal objects within the field of view. Thus, the above-described advantages of laser systems and methods having an ability to automatically determine a range to an object detected within a field of view, and to automatically adjust the laser (e.g. illumination intensity, etc.) to reduce a potential risk to the object, may be achieved using a system300having separate laser and ranging components310,350that cooperatively perform the desired functionality.

FIG. 8is an exemplary environment400having a laser system410that includes a ranging system450in accordance with yet another embodiment of the present disclosure. The laser system410directs a laser beam420along a beam axis422toward a target402. At least part of the laser beam420that impinges on the target402is reflected as target reflections424(specular or non-specular) from the target402back toward the laser system410.

In this embodiment, the ranging system450monitors for the presence of objects within a field of view430that is larger than (and substantially inclusive of) the laser beam420. For example, in addition to the target402, a first intermediate object404(e.g. a vehicle) and a second intermediate object406(e.g. a person) are situated at least partially within the field of view430. Both intermediate objects404,406are outside the laser beam430.

Ranging signals452are emitted by the ranging system450within the field of view430. First reflected signals454are reflected from the first intermediate object404, second reflected signals456are reflected from the second intermediate object406, and target reflected signals458are reflected from the target402. The ranging system450receives at least a portion of the reflected signals454,456,458, and determines a first distance D1to the first intermediate object404, a second distance D2to the second intermediate object406, and a target distance DTto the target402. These distances may then be compared with a standoff distance DS, and necessary adjustments (if any) may be made, as described above.

Embodiments of systems and methods in accordance with the present disclosure having a ranging system that operates using a field of view that is larger than an associated laser beam may provide additional advantages. Because the field of view extends laterally beyond the laser beam, the laser system may detect intermediate objects, and make necessary adjustments to the laser beam, before the intermediate objects actually enter the laser beam. This aspect may be a valuable aspect in some applications, particularly for relatively high power laser applications.

FIG. 9is a process500for operating a laser system in accordance with a further embodiment of the present disclosure. In this embodiment, the process500includes operating a laser system to provide a laser beam toward a target at502. The operating conditions of the laser system establish a standoff distance. At504, a ranging system is operated to determine a distance to a nearest object within a field of view (FOV). In some embodiments, the field of view is coincident with the laser beam. Alternately, the field of view may be larger than the laser beam. The ranging system may be operated simultaneously or sequentially with the laser system. In some embodiments, the ranging system provides its own ranging signals, while in other embodiments, the ranging system uses reflected laser light generated by the laser system.

At506, the process500determines whether the distance to the nearest object within the field of view compares favorably with the standoff distance. For example, in some embodiments, the standoff distance is based on the NOHD portion of the laser beam (i.e. the near-range exposure danger zone for human vision), and the distance to the nearest object compares favorably when it is greater than the standoff distance, and compares unfavorably when it is not greater than the standoff distance. If the comparison is favorable (at506), then the process500returns to502and continues performing the above-noted activities indefinitely (502through506).

On the other hand, if the distance to the nearest object within the field of view compares unfavorably with the standoff distance (at506), then the process500adjusts one or more of the laser operating conditions at508. For example, in some embodiments, a control system may controllably adjust one or more of a laser source and a beam directing assembly in order to adjust a standoff distance of the laser beam.

Next, after performing the adjustment at508, the process500may determine whether a limit condition has been reached at510. For example, the process500may determine whether some type of lower (or minimum) operating limit has been reached on a laser operating condition (e.g. output power, divergence angle, etc.) so that continued operation of the laser is no longer practical or suitable for its intended purpose. If the determination at510is affirmative, the process500proceeds to shutdown at512. Alternately, if no limit condition has been reached (at510), then the process500returns to502, and continues performing the above-described actions (502through510) indefinitely.

It will be appreciated that the process500is one possible implementation in accordance with the present disclosure, and that the present disclosure is not limited to the particular process implementations described herein and shown in the accompanying figures. For example, in alternate implementations, certain acts need not be performed in the order described, and may be modified, and/or may be omitted entirely, depending on the circumstances. Moreover, in various implementations, the acts described may be implemented by a computer, controller, processor, programmable device, or any other suitable device, and may be based on instructions stored on one or more computer-readable media or otherwise stored or programmed into such devices. In the event that computer-readable media are used, the computer-readable media can be any available media that can be accessed by a device to implement the instructions stored thereon.

It will be appreciated that various embodiments of laser systems operable for implementing techniques in accordance with the present disclosure may be conceived. For example,FIG. 10is a schematic view of a laser system600in accordance with another embodiment of the present disclosure. In this embodiment, the laser system600includes a warning laser602coupled by an umbilical cable604to a safety and control module (SCM)650. In some embodiments, the warning laser602may be a visible wavelength laser (e.g. green wavelength, GDB-IIIC H&W laser) configured for directing a warning flash as a non-lethal deterrent toward a target610. A switch606(e.g. a tape switch) is coupled by a switch cable608to the safety and control module620to enable remote activation (or de-activation) of the safety and control module620by an operator (not shown). The safety and control module620includes a primary control (or “On/Off”) switch626, a “Lock-Out” LED (Light-Emitting Diode)627that may be illuminated to indicate that the safety and control module620is in a lock-out or non-operational state, and an “Active” LED629that may be illuminated to indicate that the safety and control module620is operational. One or more batteries628provide power to the safety and control module620.

FIG. 11is a schematic view of the safety and control module620of the laser system600ofFIG. 10in accordance with another embodiment of the present disclosure. In this embodiment, the safety and control module620includes a primary module (or printed circuit assembly PCA)630coupled to a transmission module (or PCA)640by a first signal conductor622. A receiver module650is coupled to the primary module630by a second signal conductor624. The primary control (or on/off) switch626, the Lock-Out LED627, and the Active LED629are also coupled to the primary module630by the second signal conductor624. A first keyed connector623couples the primary module630to the switch cable608, and a second keyed connector625couples the primary module630with the umbilical cable604.

The transmission module640includes a laser source642. In some embodiments, the laser source642may be a laser diode that emits a laser signal644(e.g. an infrared 905 nm signal) (shown inFIG. 10) through one or more transmission components646(e.g. optical components, etc.) toward the target610. Similarly, the receiver module650includes a sensor652that detects a reflected signal654(shown inFIG. 10) from the target610. The reflected signal654reaches the sensor652via one or more reception components656(e.g. optical components, filter, etc.).

As further shown inFIG. 11, in this embodiment, the primary module630includes a power supply632that provides power to the other components of the primary module630. A processor634receives and processes input signals, such as those from the receiver module650, and provides corresponding control signals to other components of the safety and control module620. An accelerometer636(e.g. a 3-axis accelerometer) senses movement of the safety and control module620and provides corresponding information on the movement of the safety and control module620to the processor634. A field-programmable gate array (FPGA)638is operable to receive command signals from the processor634, and provide corresponding output signals to the transmission module640.

In operation, the safety and control module650is operable to determine a target distance660between the laser system600and the target610. More specifically, the primary module630of the safety and control module600may trigger the transmit module640to provide a high voltage pulse to the laser source642, sending the laser signal644to the target610. The receiver module650indicates a detection of the reflected signal654to the primary module630, and the primary module630calculates the target distance660(e.g. using a time-of-flight model or other suitable technique). If the target distance660is less than an acceptable distance (e.g. a Nominal Ocular Hazard Distance (NOHD)), the primary module630may adjust (including shut-down) the output of the warning laser602to avoid potential harm to the target610.

The detailed descriptions of the above embodiments are not exhaustive descriptions of all embodiments contemplated by the inventors to be within the scope of the invention. Indeed, persons skilled in the art will recognize that certain elements of the above-described embodiments may variously be combined or eliminated to create further embodiments, and such further embodiments fall within the scope and teachings of the invention. It will also be apparent to those of ordinary skill in the art that the above-described embodiments may be combined in whole or in part to create additional embodiments within the scope and teachings of the present disclosure. Accordingly, the scope of the invention should be determined from the following claims.