Patent Description:
A laser detection system can be used to illuminate one or more objects using pulsed laser light, where reflected pulses from the objects are received and analyzed in order to identify information about the objects. For example, a laser detection system may be used to illuminate a moving object in order to determine a range to the object. In this way, the system can be used to identify the distance to the object and the speed of the object.

<NPL> discloses a 3D (angle-angle-range) imaging laser radar (LADAR) based on multiple-input multiple-output structures.

<CIT> discloses a system for monitoring wind characteristics in a volume including a plurality of non-coherent laser anemometers operative to measure wind characteristics in a plurality of corresponding sub-volumes located within the volume and a data processing subsystem operative to receive data from the plurality of non-coherent laser anemometers and to provide output data representing the wind characteristics in the volume.

<CIT> discloses a laser doppler velocimeter.

This disclosure provides a fiber-bundled frequency-shifted transmitter for direct-detection LIDAR.

In a first embodiment, a method includes generating, using a transmitter, an optical signal for each fiber incoherently combined in a fiber bundle. The method also includes transmitting the optical signal from each fiber as pulses at a target. The method further includes receiving, using a receiver array, the pulses of the optical signals and identifying one or more parameters of the target based on the pulses of the optical signals. The method further comprises offsetting an optical frequency of the optical signal for each fiber wherein the one or more parameters of the target are identified using the optical signals with offset optical frequencies, wherein the optical frequencies are offset by a pulse repetition frequency of the pulses.

In a second embodiment, a system includes a transmitter configured to generate an optical signal for each fiber incoherently combined in a fiber bundle and transmit the optical signal from each fiber as pulses at a target. The system also includes a receiver array configured to receive the pulses of the optical signals. The system further includes a signal processor configured to identify one or more parameters of the target based on the pulses of the optical signals. The transmitter is further configured to offset an optical frequency of the optical signal for each fiber; the one or more parameters of the target are identified using the optical signals with offset optical frequencies, wherein the transmitter is configured to offset the optical frequencies by a pulse repetition frequency of the pulses.

In a third embodiment, an apparatus includes a transmitter configured to generate an optical signal for each fiber incoherently combined in a fiber bundle and transmit the optical signal from each fiber as pulses at a target. The apparatus also includes a receiver array configured to receive the pulses of the optical signals. The apparatus further includes a signal processor configured to identify one or more parameters of the target based on the pulses of the optical signals. The apparatus also includes a housing for containing the transmitter, the receiver array and the signal processor. The transmitter is further configured to offset an optical frequency of the optical signal for each fiber; the one or more parameters of the target are identified using the optical signals with offset optical frequencies, wherein the transmitter is configured to offset the optical frequencies by a pulse repetition frequency of the pulses.

<FIG>, described below, and the various embodiments used to describe the principles of the present disclosure are by way of illustration only and should not be construed in any way to limit the scope. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any type of suitably arranged device or system.

Many long-range direct detection LIDAR systems require an agile laser transmitter emitting high-energy pulses of adjustable repetition rate, duration, and temporal profile. In many applications of interest, a LIDAR system of low size, weight, and power (SWaP) and capable of operating in the eye-safe region of the electromagnetic spectrum at wavelengths greater than <NUM>. Pulsed fiber lasers (PFLs) can advantageously be used in such LIDAR systems owing to their high degree of pulse-format agility (including architectures in which the pulse rep. rate, width, and shape can dynamically be modified on a pulse to pulse basis), compact form factor, inherent ruggedness, high reliability, and direct emission at eye-safe wavelengths. However, PFLs are subj ect to nonlinear optical effects, which limit the achievable pulse energy and peak power to lower values compared, for example, to bulk solid-state lasers. This disclosure teaches an approach to circumventing this limitation through the incoherent combination of an array of PFLs terminated by a fiber bundle, such that the beamlets exiting each element of the array form a single beam in the far field carrying the cumulative power of all arrayed PFLs. In some embodiment, the disclosure also teaches methods to smoothen the spatial speckle pattern of the array-emitted beam at the target location by mutually frequency-offsetting the arrayed PFLs. In particular, if the optical frequencies of the arrayed PFLs differ by an amount greater than the pulse repetition rate, each pulse is associated with a different realization of speckle pattern such that averaging LIDAR returns over several (for example, <NUM> or more) pulses results in the detection of a smoothly illuminated spot at the target.

<FIG> illustrates an example laser system <NUM> and laser apparatus <NUM> according to this disclosure. As shown in <FIG>, the system <NUM> is used to detect one or more targets <NUM> and one or more parameters associated with each of the targets <NUM>. In this example, the target <NUM> is a randomly-shaped object, although this is for illustration only. Any suitable target or targets <NUM> may be detected by the system <NUM>. Example targets <NUM> that may be detected by the system <NUM> can include drones or other aerial vehicles, trucks or other ground-based vehicles, or other objects of interest. The system <NUM> may also be used to identify any suitable parameter or parameters of interest related to the target(s) <NUM>. Example parameters that may be detected by the system <NUM> include range (distance) and Doppler velocity (speed) of each target <NUM>.

The system <NUM> here includes transmitter electronics <NUM> and a transmitter <NUM>. The transmitter electronics <NUM> generally operate to generate one or more electrical signals, and the transmitter <NUM> generally operates to convert the electrical signal(s) into one or more optical signals for transmission. For example, the transmitter electronics <NUM> may include electrical components that generate at least one electrical signal having at least one desired waveform (including frequency-shifted pulses), and the transmitter <NUM> may generate at least one laser signal having the same waveform(s). The transmitter electronics <NUM> include any suitable structure for controlling operation of a transmitter. The transmitter <NUM> includes any suitable structure for generating at least one laser signal or other optical signal containing pulses.

The at least one optical signal from the transmitter <NUM> is provided via transmit/receive optics <NUM> to a telescope <NUM>. The transmit/receive optics <NUM> function as a transmit/receive switch and allow both outgoing and incoming optical signals to pass through the telescope <NUM>. The transmit/receive optics <NUM> include any suitable optical device or devices for facilitating both transmission and reception of optical signals through a telescope or other common structure.

The telescope <NUM> generally operates to direct at least one outgoing optical signal <NUM> towards one or more targets <NUM>. The at least one optical signal <NUM> denotes the at least one optical signal generated by the transmitter <NUM> and includes a number of pulses, including frequency-shifted pulses, in a desired waveform. The transmission of the optical signal(s) <NUM> towards the target <NUM> results in reflected laser light <NUM> that can travel in various directions from the target <NUM>. At least some of the reflected laser light <NUM> travels back to the telescope <NUM> as at least one reflected optical signal <NUM>. The telescope <NUM> can therefore be used to direct laser pulses toward a target <NUM> of interest and to receive reflected laser pulses from the target <NUM>. The telescope <NUM> may include focusing optics or other optical devices to facilitate the directing of pulses towards one or more targets <NUM> and the receipt of reflected pulses from the target(s) <NUM>. The telescope <NUM> includes any suitable structure for directing and receiving optical signals.

The at least one reflected optical signal <NUM> received by the telescope <NUM> is directed through the transmit/receive optics <NUM> to a receiver that processes the at least one reflected optical signal <NUM>. In this example, the at least one reflected optical signal <NUM> is directed to a detector array <NUM>. The detector array <NUM> receives the at least one reflected optical signal <NUM> and generates at least one output, which is based on the at least one reflected optical signal <NUM>. For example, the output of the detector array <NUM> may include pulses contained in the reflected optical signal(s) <NUM>. Detector electronics <NUM> use the output of the detector array <NUM> to identify pulses in the optical signal(s) <NUM>. The identified pulses are analyzed by a signal processor <NUM>, which can use the pulses to detect the target <NUM> and one or more parameters of the target <NUM> (such as range and Doppler velocity).

The detector array <NUM> includes any suitable structure for receiving optical signals. The detector electronics <NUM> include any suitable structure for detecting optical signals, such as a Geiger Mode Avalanche Photo Diodes (GMAPD) detector array. The signal processor <NUM> includes any suitable structure for analyzing signals, such as a microprocessor, microcontroller, digital signal processor (DSP), field programmable gate array (FPGA), application specific integrated circuit (ASIC), or discrete logic devices. In some embodiments, the signal processor <NUM> may execute software instructions for detecting and analyzing pulses as described below.

The outputs of the signal processor <NUM> may be used in any suitable manner. In this example, the outputs of the signal processor <NUM> can be presented on a display device <NUM> (such as a monitor) or stored on a storage device <NUM> (such as a RAM, ROM, Flash memory, hard drive, or optical disc). Note, however, that the outputs of the signal processor <NUM> may be used in any other suitable manner and may be provided to any other suitable devices or systems.

As shown in <FIG>, a laser apparatus <NUM> is used to detect one or more targets <NUM> and one or more parameters associated with each of the targets <NUM>. The laser apparatus <NUM> can include a housing <NUM> for containing one or more components of the laser system <NUM>, including transmitter electronics <NUM>, transmitter <NUM>, transmit/receive optic <NUM>, telescope <NUM>, detector array <NUM>, detector electronics <NUM>, signal processor <NUM>, display <NUM>, and storage <NUM>. In certain embodiments, the housing <NUM> can be a shell of a projectile, a skin of an airplane or helicopter, etc..

Although <FIG> illustrate examples of a laser system <NUM> and a laser apparatus <NUM>, various changes may be made to <FIG>. For example, the system <NUM> in <FIG> is shown in simplified form to facilitate an easier understanding of this disclosure. Laser detection systems can include a number of other or additional components that perform a wide variety of functions.

<FIG> and <FIG> illustrate example uses of multiple transmitting beams to illuminate a field of view of a receiver array according to this disclosure. More specifically, <FIG> and <FIG> illustrate example uses of multiple transmitted optical signals <NUM> to illuminate a field of view (FOV) of various detectors <NUM> in a detector array <NUM>. In <FIG>, it is assumed that the laser system <NUM> includes a receiver aperture <NUM> and multiple transmitting apertures <NUM> around the receiver aperture <NUM>. In <FIG>, it is assumed that the laser system <NUM> includes a receiver aperture <NUM> and multiple transmitting apertures <NUM> within the receiver aperture <NUM>. Note that various components in <FIG> and <FIG> may reside within or be used as part of the transmitter electronics <NUM>, telescope <NUM>, detector array <NUM>, or other portions of the system <NUM>.

As shown in <FIG>, the detector array <NUM> includes a plurality of detectors <NUM>. While illustrated as a one-dimensional array of detectors <NUM> here for simplicity, the detector array <NUM> may have a multi-dimensional array of detectors <NUM>. Each detector <NUM> can detect at least one reflected optical signal <NUM>, which can be used by the detector electronics <NUM> and the signal processor <NUM> to determine one or more parameters of an object or a scene.

The telescope <NUM> can be generally divided into at least two sections, namely a receiver aperture <NUM> and multiple transmitting apertures <NUM>. The receiver aperture <NUM> is aligned with the detector array <NUM> in order to receive at least one reflected optical signal <NUM> across an entire FOV <NUM>. The receiver aperture <NUM> focuses a reflected optical signal from each instantaneous FOV <NUM> to a specific detector <NUM> in the detector array <NUM>. Here, each instantaneous FOV <NUM> corresponds to one of the detectors <NUM>, and the collection of instantaneous FOVs <NUM> forms the entire FOV <NUM>. The receiver aperture <NUM> includes any suitable structure for focusing a laser signal or other optical signal containing pulses on a detector array <NUM>.

As shown in <FIG>, each of the transmitting apertures <NUM> focuses a transmitted optical signal <NUM> across the entire FOV <NUM>. A number of transmitting apertures <NUM> corresponds to a number of transmitted optical signals <NUM>. The transmitting apertures <NUM> can be arranged in any suitable manner, such as in a group on a side of the receiver aperture <NUM> or on different sides or around the receiver aperture <NUM>. Because the transmitting apertures <NUM> are used to spread transmitted optical signals <NUM> across the entire FOV <NUM>, a size of each transmitting aperture <NUM> can be much smaller than the receiver aperture <NUM>. Each transmitting aperture <NUM> is structured to have a transmitting aperture DT. The cumulation of transmitting apertures <NUM> are structured or arranged to have a combine transmitting aperture Dc which is equal to a number N of transmitting apertures <NUM> in one dimension multiplied by the single transmitting aperture DT. Each transmitting aperture <NUM> includes any suitable structure for spreading a laser signal or other optical signal towards a target <NUM>. In some cases, the transmitting apertures <NUM> can be located in an array outside of the receiving aperture <NUM>, where a size of the receiving aperture <NUM> is reduced to accommodate the transmitting apertures <NUM>. When a diameter of the receiver aperture <NUM> is reduced by <NUM>/<NUM>, the area is reduced by <NUM>/<NUM> or <NUM>%. This reduction is ideal for maintaining functionality of the LADAR system <NUM>. For optimal efficiency of the telescope <NUM>, the diameter of the receiver aperture <NUM> should be greater than twice the cumulative or effective diameter of the transmitting apparatus <NUM>. Where the cumulative or effective diameter of the transmitting aperture <NUM> corresponds to a distance based on a reduction of a maximum diameter of the receiving aperture <NUM> inside the telescope <NUM>.

Small areas of the receiver aperture <NUM> can be used for the transmitting apertures <NUM>, resulting in a single lens or a receiver aperture <NUM> with portions removed to fit the transmitting apertures <NUM>. An amount of observation for an amount of the receiver aperture <NUM> removed may be negligible based on a size of the transmitting apertures <NUM>.

As noted above, each of the detectors <NUM> corresponds to a small portion of the entire FOV <NUM>, where that portion is referred to an instantaneous FOV <NUM>. The instantaneous FOV <NUM> can be determined by multiplying a range <NUM> by λ divided by a receiver diopter DR of the receiver aperture <NUM>, where λ is a wavelength of light. Multiple instantaneous FOVs <NUM> define the total area of the FOV <NUM>. Also as noted above, each of the transmitting apertures <NUM> can be designed to spread each transmitted optical signal <NUM> across the entire FOV <NUM>. A transmitting aperture DT can be determined based on the following: <MAT> where the right side of Equation (<NUM>) defines an illumination area for the transmitted optical signals <NUM>, R represents a range <NUM> of the target <NUM> from the system <NUM>, and M represents a number of detectors <NUM> in one dimension of an array.

The usable range <NUM> depends on a power of the laser(s) used for the transmitted optical signals <NUM>. Generating more power for the laser(s) can increase the range <NUM> of the system <NUM>. In some cases, at least one fiber laser may be used as a laser generator, although other types of lasers may be used here.

As an example, an array of transmitting apertures <NUM> is positioned within the receiver aperture <NUM>. Assuming a diffraction limit and an array of M×M detectors <NUM> in the detector array <NUM>, a ratio of DR over DT is approximately equal to M. This would make a size of the transmitting aperture <NUM> approximately equal to DR divided by the number N of transmitted optical signals <NUM> in one direction of the array.

When the transmitter <NUM> is N× diffraction limited based on using an N×N array of transmitting apertures <NUM>, in order to maintain the illumination FOV, a size of the combined transmitting apertures <NUM> may be approximately equal to a size of the receiver aperture <NUM> multiplied by N/M. When the transmitter <NUM> is efficiency factor (β) diffraction limited, the combined transmitting aperture <NUM> may be approximately equal to a size of the receiver aperture <NUM> multiplied by β (N/M). As a non-limiting example, the efficiency factor can be in a range of <NUM> to <NUM>, and the ratio of N/M with the efficiency factor may be approximately <NUM>.

Although <FIG> and <FIG> illustrate example uses of multiple transmitted optical signals <NUM> to illuminate a FOV of a detector array <NUM>, various changes may be made to <FIG> and <FIG>. For example, the telescope <NUM> shown in <FIG> and <FIG> is for illustration only. Also, various components in <FIG> and <FIG> may be combined, further subdivided, rearranged, or omitted and additional components may be added according to particular needs.

<FIG> and <FIG> illustrate example laser sources for a transmitter according to this disclosure. In particular, <FIG> illustrates an example transmitter <NUM> with an independent laser source for each fiber amplifier, and <FIG> illustrates an example transmitter <NUM> with a single laser source split among a plurality of fiber amplifiers. For ease of explanation, the transmitters <NUM> and <NUM> in <FIG> and <FIG> are described as being used in the system <NUM> of <FIG>. However, the transmitter <NUM> and <NUM> may be supported by any other suitable system.

As shown in <FIG>, a multi-source transmitter <NUM> can include pulse driver electronics <NUM>, multiple optical signal sources <NUM>, and multiple fiber amplifiers <NUM>. The multi-source transmitter <NUM> generates and transmits optical signals <NUM> through a fiber bundle <NUM>. The multi-source transmitter <NUM> includes any suitable structure for generating and transmitting optical signals <NUM> through a fiber bundle <NUM>. In some embodiments, the multi-source transmitter <NUM> can be implemented as at least part of the transmitter electronics <NUM> shown in <FIG>.

The pulse driver electronics <NUM> control the operation of the optical signal sources <NUM> to thereby control the generation of the transmitted optical signals <NUM>. For instance, the pulse driver electronics <NUM> may control when the optical signal sources <NUM> are operating and how optical pulses are generated by the optical signal sources <NUM>. The optical signal sources <NUM> include any suitable structure(s) for modulating or generating optical signals. The pulse driver electronics <NUM> include any suitable structure for controlling electro-optical modulation or other generation of optical signals and for controlling pulses in optical signals.

The optical signal sources <NUM> are coupled to fibers <NUM> in the fiber bundle <NUM>. The optical signal sources <NUM> are controlled by the pulse driver electronics <NUM> to generate optical pulses for each fiber <NUM>. The optical signal sources <NUM> can also be controlled by the pulse driver electronics <NUM> to generate a suitable frequency offset for each of the optical pulses. In this example, the optical signal sources <NUM> output the generated optical pulses to a fiber amplifier <NUM>, which can amplify the optical pulses for transmission towards at least one target <NUM> as the transmitted optical signals <NUM>. The fiber amplifier <NUM> includes any suitable structure for amplifying optical signals, such as one or more laser pump diodes or other optical pump that provides optical energy used for amplification.

The fibers <NUM> in this example are coupled to an output of the fiber amplifier <NUM>. The fibers <NUM> collectively are referred to as the fiber bundle <NUM>. Each fiber <NUM> includes any suitable structure for transmitting optical signals.

As shown in <FIG>, the single-source transmitter <NUM> can include pulse driver electronics <NUM>, an optical signal source <NUM>, multiple fiber amplifiers <NUM>, and multiple frequency shifters <NUM>. The single-source transmitter <NUM> includes an optical signal source <NUM> that generates and transmits optical signals <NUM> through a fiber bundle <NUM>. The single-source transmitter <NUM> includes any suitable structure for generating and transmitting optical signals <NUM> through a fiber bundle <NUM>. In some embodiments, the single-source transmitter <NUM> can be implemented as at least part of the transmitter electronics <NUM> shown in <FIG>.

A frequency shifter <NUM> can be implemented for each fiber <NUM> to receive the output from the optical signal source <NUM> and shift a frequency of the output. Each frequency shifter <NUM> may include frequency driver electronics to control the operation of the frequency shifter <NUM> to thereby control the frequency shift. For instance, frequency driver electronics may control when the frequency shifter <NUM> is operating and how the frequency shifter <NUM> shifts the output of the optical signal source <NUM>. Each frequency shifter <NUM> includes any suitable structure for shifting the frequency of optical signals. The frequency driver electronics can include any suitable structure for controlling frequency shifting of optical signals. The output for each of the frequency shifters <NUM> is fed into a respective fiber amplifier <NUM>.

Although <FIG> and <FIG> illustrate examples of laser sources for a transmitter <NUM>, various changes may be made to <FIG> and <FIG>. For example, any suitable number of optical signal sources <NUM> may be used with any suitable number of fibers <NUM>.

<FIG> illustrate example illumination spots at different phase errors according to this disclosure, and <FIG> illustrate example illumination spots based on offsetting an optical frequency of each channel according to this disclosure. In particular, <FIG> illustrates an illumination spot <NUM> at a π/<NUM> phase error, when the fibers would be phase locked, <FIG> illustrates an illumination spot <NUM> at a π/<NUM> phase error, <FIG> illustrates an illumination spot <NUM> at a π/<NUM> phase error, <FIG> illustrates an illumination spot <NUM> at a 2π/<NUM> phase error, and <FIG> illustrates an illumination spot <NUM> at when the fibers are incoherently combined at the same frequency but at a completely random phase (i.e. maximum phase error). Also, <FIG> illustrates a single realization illumination spot <NUM>, and <FIG> illustrates a <NUM>-pulse average illumination spot <NUM>. For ease of explanation, the results shown in <FIG> are described as being obtained by the system <NUM> of <FIG>. However, the system or other laser system designed in accordance with the teachings of this disclosure may obtain any other suitable results depending on the implementation.

As shown in <FIG>, the illumination spots <NUM>-<NUM> are generated based on phase errors. If a laser source array is coherently combined, an illumination spot will be λ/DT, where DT is the transmission aperture. The illumination spot <NUM> is based on a fiber bundle with the individual fibers fully coherently combined. If the laser source array is incoherently combined, the illumination spot will be N×λ/DT, where N is the number of lasers in one dimension (such as in an NxN array of lasers). The illumination spot <NUM> is based on a fiber bundle that is incoherently combined. There is also the possibility that the lasers are somewhat coherently combined, where there is some phase error in the combination that would make an illumination spot be somewhere between the two extremes of illumination spot <NUM> and illumination spot <NUM>. In other functions of fiber bundles, the fully coherent illumination spot is ideal. For LIDAR, the incoherently bundled fibers provide unexpected results benefitting the identifying one or more parameters of a target.

As shown in <FIG>, a single realization illumination spot <NUM> is generated from a single received pulse. The pulse averaging illumination spot <NUM> is generated from multiple pulses received, and the detected patterns are averaged to reduce speckle. By offsetting the optical frequency of each channel by at least the pulse repetition frequency of the laser pulses, a new independent speckle pattern can be created at each frame, which smooths out the effects of the speckle.

Although <FIG> illustrate examples of illumination spots at different phase errors and <FIG> illustrate examples of illumination spots based on offsetting an optical frequency of each channel, various changes may be made to <FIG>. For example, the information contained in the various plots of <FIG> are for illustration only and are merely meant to illustrate the types of results that may be obtained by the system <NUM> using different waveforms.

<FIG> illustrates an example method <NUM> for operating a laser system according to this disclosure. For ease of explanation, the method <NUM> of <FIG> is described as being performed using the laser system <NUM> of <FIG> with the transmitter <NUM> of <FIG> or <FIG>. However, the method <NUM> may be used with any other suitable system and any other suitable transmitter.

As shown in <FIG>, an optical signal <NUM> for each fiber <NUM> incoherently combined in a fiber bundle <NUM> is generated at step <NUM>. This may include, for example, the transmitter <NUM> using multiple optical sources <NUM> to generate multiple optical signals <NUM>, where the optical signal <NUM> for each fiber <NUM> is generated by an optical source <NUM> specifically designated for the fiber <NUM>. Alternatively, this may include the transmitter <NUM> using an optical source <NUM> to generate multiple optical signals <NUM> for multiple fibers <NUM>. The fibers are combined in an incoherent way or in a manner that their optical phases are not altered or otherwise actively controlled.

Pulses of the optical signals <NUM> are frequency shifted at step <NUM>. This may include, for example, the transmitter <NUM> of the system <NUM> using pulse driver electronics <NUM> to control multiple optical sources <NUM> in order to cause the pulses from the optical sources <NUM> to be frequency offset. Alternatively, this may include the transmitter <NUM> of the system <NUM> using a single laser source <NUM> controlled by the pulse driver electronics <NUM> and using a frequency shifter <NUM> in each fiber <NUM> to shift the frequencies of the optical signals <NUM>.

Each optical signal <NUM> is transmitted from the associated fiber <NUM> as pulses at a target <NUM> at step <NUM>, and a reflection of each optical signal <NUM> is received at a detector array <NUM> at step <NUM>. In some cases, the detector array <NUM> may be formed using detectors <NUM> in a one-dimensional or multi-dimensional array. Each detector <NUM> may be designed and arranged for use with the receiver aperture <NUM> to detect a reflected optical signal <NUM> for an instantaneous FOV <NUM>. Combining the instantaneous FOVs <NUM> for the detectors <NUM> defines an entire FOV <NUM> for the receiver of the laser system. Each of the fibers <NUM> may be designed and arranged with a transmitting aperture <NUM> to transmit the pulses of the associated optical signal <NUM> across the entire FOV <NUM>.

One or more parameters of the target <NUM> are identified based on the pulses of the reflected optical signals <NUM> with offset optical frequencies at step <NUM>. This may include, for example, the signal processor <NUM> of the system <NUM> using the results to identify a range to the target <NUM> and a range rate of the target <NUM>. Other information related to the target <NUM> may also or alternatively be generated based on the processing of the pulses in the reflected optical signal <NUM>. The one or more parameters of the target can be output or used at step <NUM>. This may include, for example, the signal processor <NUM> of the system <NUM> outputting the parameter(s) of the target <NUM> to a display <NUM> for presentation or to a storage device <NUM> for temporary or long-term storage. The parameters of the target <NUM> may also or alternatively be used in any other suitable manner.

Although <FIG> illustrates one example of a method <NUM> for operating a laser system, various changes may be made to <FIG>. For example, while shown as a series of steps, various steps in <FIG> may overlap, occur in parallel, or occur any number of times.

In some embodiments, various functions described in this patent document are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium.

Claim 1:
A method (<NUM>) comprising:
generating (<NUM>), using a transmitter (<NUM>), an optical signal (<NUM>) for each fiber (<NUM>) incoherently combined in a fiber bundle (<NUM>);
transmitting (<NUM>) the optical signal (<NUM>) from each fiber (<NUM>) as pulses at a target (<NUM>);
receiving (<NUM>), using a receiver array (<NUM>), the pulses of the optical signals (<NUM>); and
identifying (<NUM>) one or more parameters of the target (<NUM>) based on the pulses of the optical signals (<NUM>), further comprising:
offsetting (<NUM>) an optical frequency of the optical signal (<NUM>) for each fiber (<NUM>),
wherein the one or more parameters of the target (<NUM>) are identified using the optical signals (<NUM>) with offset optical frequencies, and wherein the optical frequencies are offset by a pulse repetition frequency of the pulses.