Patent Description:
Lasers are able to deliver concentrated light energy over significant distances when there is no contamination in the light path. However, atmospheric distortions and contamination such as differing turbulence states, particulates such as dust or high humidity such as clouds in the light path will to varying degrees reflect, absorb and scatter light incident thereon, meaning that the delivered intensity is reduced. Even small amounts of contamination in the light path can significantly reduce the amount of energy delivered to a target, particularly when the contamination is located close to the laser source.

An exemplary laser system is described in <CIT>.

Reduction of delivered intensity caused by contamination or atmospheric distortions in the light path is a problem for laser directed energy weapons (LDEWs). These problems may be serious at ground level and at sea, with factors such as salt spray or dusty desert environments exacerbating the issues. Different atmospheric effects at different times or on different days, such weather or pollen count, can affect fixed installations. Vehicle-mounted LDEWs may encounter varying environmental conditions as they move, for example if flying in and out of clouds. Furthermore, vehicle-mounted LDEWs often have operational limitations, for example a maximum operation duration or a minimum time between operations, owing to the constraints made to enable the LDEW to be small and light enough to be mobile, or otherwise integrated in to the power generation and thermal management systems of a vehicle. This means that there are often additional constraints to consider when controlling the laser of LDEWs, and in particular vehicle-mounted LDEWs.

Therefore, there is a need for a suitable laser controller to control when and how to operate a laser according to environmental conditions that may affect the light path.

In one aspect there is provided a laser controller in accordance with claim <NUM>. This laser controler comprises:.

The backscatter detector is operable to detect backscattered radiation resulting from operation of the electromagnetic radiation source.

The processor is operable to generate a laser control signal for selectively enabling and disabling operation of a laser controlled by the laser controller.

The processor is operable to generate a laser control signal for disabling operation of a laser controlled by the laser controller when the intensity of the detected backscattered radiation is above a cut-off threshold level.

In one example, the backscatter detector is operable to detect backscattered radiation at a first distance range relative to the electromagnetic radiation source.

In one example, the backscatter detector and is operable to detect backscattered radiation within a plurality of different distance ranges relative to the electromagnetic radiation source.

In one example, the backscatter detector is operable to detect backscattered radiation within a plurality of distance ranges from the electromagnetic radiation source, starting with a first distance, and moving to one or more greater distances from the electromagnetic radiation source.

In one example, the processor is operable to generate a laser control signal based on characteristics of the detected backscattered radiation including intensity of the detected backscattered radiation.

In one example, the processor is operable to generate a laser control signal for enabling operation of a laser controlled by the laser controller when the intensity of the detected backscattered radiation is below a cut-off threshold level.

In one example, the processor is operable to generate a laser control signal for modulating the operational power of a laser controlled by the laser controller according to the intensity of the backscattered radiation. In one example, the processor is operable to generate a laser control signal for increasing the operation power of a laser controlled by the laser controller above a default power when the intensity of the backscattered radiation is between a first modulation threshold and a second modulation threshold.

In one example the second modulation threshold is below the cut-off threshold level.

In one example, the electromagnetic radiation source is operable to transmit ultra-violet radiation. In one example the electromagnetic radiation source is a laser. In one example, the electromagnetic radiation source is operable independently of a laser controlled by the laser control signal.

In one example, the backscatter detector comprises an interferometer.

In one example, the electromagnetic radiation source and backscatter detector are parts of a gas velocity sensor. In one example the gas velocity sensor comprises Doppler frequency shift sensor.

In one example, the laser controller is operable to control a laser of a LDEW using the laser control signal. In one example the laser controller is integral with a LDEW. In one example, the electromagnetic radiation source is operable to transmit radiation in a direction aligned with the laser of the LDEW. In one example, the radiation source is operable to transmit radiation along the same axis as the laser of the LDEW. In one example, the laser controller is integral with a LDEW, and arranged to operate the laser of the LDEW as the electromagnetic radiation source.

In another aspect there is provided a vehicle comprising a laser controller as set out herein. In one example the vehicle comprises an aircraft.

In another aspect there is provided a method of controlling a laser accordance with claim <NUM>. The method comprises operating an electromagnetic radiation source to transmit radiation into the environment; operating a backscatter detector to detect backscattered radiation from the environment; and generating a laser control signal based on characteristics of the detected backscattered radiation. The method is performed by a laser controller as set out herein.

In one example, the method is performed in a vehicle as set out herein.

The method comprises operating the backscatter detector to detect backscattered radiation resulting from operation of the electromagnetic radiation source.

In one example, the method comprises operating the backscatter detector to detect backscattered radiation at a first distance range relative to the electromagnetic radiation source.

In one example, the method comprises operating the backscatter detector to detect backscattered radiation within a plurality of different distance ranges relative to the electromagnetic radiation source.

In one example, the method comprises operating the backscatter detector and to detect backscattered radiation within a plurality of distance ranges from the electromagnetic radiation source, starting with a first distance, and moving to one or more greater distances from the electromagnetic radiation source.

In one example, the method comprises generating a laser control signal based on characteristics of the detected backscattered radiation including intensity of the detected backscattered radiation.

The method comprises generating a laser control signal for selectively enabling and disabling operation of a laser controlled by the laser controller.

The method comprises generating a laser control signal for disabling operation of a laser controlled by the laser controller when the intensity of the detected backscattered radiation is above a cut-off threshold level.

In one example, the method comprises generating a laser control signal for enabling operation of a laser controlled by the laser controller when the intensity of the detected backscattered radiation is below a cut-off threshold level.

In one example, the method comprises generating a laser control signal for modulating the operational power of a laser controlled by the laser controller according to the intensity of the backscattered radiation. In one example, the method comprises generating a laser control signal for increasing the operation power of a laser controlled by the laser controller above a default power when the intensity of the backscattered radiation is between a first modulation threshold and a second modulation threshold.

In one example, the method comprises operating the electromagnetic radiation source independently of a laser controlled by the laser control signal.

In one example, the method comprises operating an electromagnetic radiation source and backscatter detector that are parts of a gas velocity sensor.

In one example, the method comprises controlling a laser of a LDEW using the laser control signal.

Referring now to <FIG>, a laser controller is denoted as a whole by the reference numeral <NUM>.

The laser controller <NUM> comprises an electromagnetic radiation source <NUM> operable to transmit radiation into an environment, a backscatter detector <NUM> operable to detect backscattered radiation from the environment, and a processor <NUM> operable to generate a laser control signal based on characteristics of the detected backscattered radiation. By detecting backscatter from the environment, the laser controller <NUM> can, using the processor <NUM>, determine suitable operating parameters for a laser under its control. For example, if the laser controller <NUM> determines, based on a large amount of backscatter, that there is no clear light path from the laser to a target, then operation of the laser can be prevented. This avoids ineffective operation of the laser.

<FIG> shows a vehicle comprising the laser controller <NUM>. In <FIG> the vehicle <NUM> comprising a laser controller <NUM> also comprises a laser <NUM>. While the vehicle <NUM> is shown here as an aircraft, it would be readily appreciated that the present invention is applicable to other types of vehicles such as ships, land vehicles and so on.

The laser <NUM> is part of a laser-directed energy weapon <NUM> (LDEW), and the laser controller <NUM> is operable to control the laser <NUM> of the LDEW <NUM> using the laser control signal. Although here depicted as two separate components the laser controller <NUM> may be integral with the LDEW <NUM>.

The backscatter detector <NUM> and electromagnetic radiation source <NUM> are parts of a gas velocity sensor that are part of the vehicle <NUM>. The gas velocity sensor comprises a Doppler frequency shift sensor, such as that described in patent publication <CIT>, filed in the name of the present applicant, the contents of which are incorporated herein by reference. The gas velocity sensor is primarily used to determine airspeed of the vehicle, but includes an ultra violet laser source and an interferometer that can also be advantageously used as the electromagnetic radiation source <NUM> and backscatter detector <NUM> of the laser controller <NUM> respectively.

The backscatter detector <NUM> in use detects backscattered radiation at a first distance range relative to the electromagnetic radiation source <NUM>. The backscatter detector <NUM>, and electromagnetic radiation source <NUM> are operable together to detect backscattered radiation within a plurality of different distance ranges relative to the electromagnetic radiation source <NUM>, starting with a first distance, and moving to one or more greater distances from the electromagnetic radiation source <NUM>. In this way, an effective maximum effective range of the LDEW can be determined, that is, a range within which the light path to the target is not too contaminated. The processor <NUM> operates to generate a laser control signal on this basis, selectively enabling and disabling operation of the laser <NUM>.

The processor <NUM> is generates a laser control signal based on characteristics of the detected backscattered radiation, including intensity of the detected backscattered radiation, as this is representative of the presence of contamination in the light path of the laser <NUM>. The processor <NUM> is configured to generate a laser control signal for disabling operation of the laser <NUM> controlled by the laser controller <NUM> when the intensity of the detected backscattered radiation is above a cut-off threshold level, and conversely the processor <NUM> is configured to generate a laser control signal for enabling operation of the laser <NUM> controlled by the laser controller <NUM> when the intensity of the detected backscattered radiation is below the cut-off threshold level.

As well as enabling/disabling the laser <NUM> as described above, the processor <NUM> is further operable to generate a laser control signal that modulates the operational power of the laser <NUM> controlled by the laser controller <NUM>, according to the intensity of the backscattered radiation. The processor <NUM> generates a laser control signal for increasing the operation power of the laser <NUM> controlled by the laser controller <NUM> above a default power when the intensity of the backscattered radiation is between a first modulation threshold and a second modulation threshold, so that an effective intensity is still delivered to a target despite some contamination in the light path.

Suitable optical arrangements are provided such that electromagnetic radiation source <NUM> transmits radiation in a direction aligned with the laser <NUM> of the LDEW <NUM>, ideally along the same axis as the laser <NUM> of the LDEW. In another embodiment, the laser controller <NUM> is arranged to operate the laser <NUM> of the LDEW <NUM> as the electromagnetic energy source <NUM>. Such embodiments do away with the requirement for a second laser source wen the laser controller <NUM> is used to control the laser of an LDEW.

<FIG> shows an example of a method of controlling a laser.

At step <NUM>, an electromagnetic radiation source is operated to transmit radiation into an environment. At step <NUM>, a backscattered detector is operated to detect backscattered radiation from the environment. At step <NUM>, a laser control signal is generated based on characteristics of the backscattered radiation.

The method is performed by the laser controller, mounted to the vehicle.

The method further comprises controlling a laser of a LDEW using the laser control signal as step <NUM>.

Steps <NUM> and <NUM> are conveniently performed using an electromagnetic radiation source and backscatter detector that comprise parts of a gas velocity sensor, such as a Doppler frequency shift sensor.

The method comprises operating the backscatter detector to detect backscattered radiation at a first distance range relative to the electromagnetic radiation source. In one example, the method comprises operating the backscatter detector to detect backscattered radiation within a plurality of different distance ranges relative to the electromagnetic radiation source, starting with a first distance, and moving to one or more greater distances from the electromagnetic radiation source. Thus, an effective maximum effective range of the LDEW can be determined, that is, a range within which the light path to the target is not too contaminated. Based on characteristics of the detected backscatter radiation, a laser control signal is generated, for selectively enabling and disabling operation of the laser.

The characteristics of the detected backscatter radiation include, for example, intensity of the detected backscattered radiation, as this is representative of the presence of contamination in the light path of the laser. A laser control signal for disabling operation of the laser controlled by the laser controller is generated when the intensity of the detected backscattered radiation is above a cut-off threshold level. Similarly, a laser control signal for enabling operation of a laser controlled by the laser controller is generated when the intensity of the detected backscattered radiation is below a cut-off threshold level.

As well as enabling/disabling the laser as described above, a laser control signal for modulating the operational power of a laser controlled by the laser controller according to the intensity of the backscattered radiation is generated. A laser control signal for increasing the operation power of a laser controlled by the laser controller above a default power is generated when the intensity of the backscattered radiation is between a first modulation threshold and a second modulation threshold, such that an effective intensity is still delivered to a target despite some contamination in the light path.

Claim 1:
A laser controller (<NUM>) comprising:
an electromagnetic radiation source (<NUM>) operable to transmit radiation into an environment;
a backscatter detector (<NUM>) operable to detect backscattered radiation resulting from operation of the electromagnetic radiation source; and
a processor (<NUM>) operable to generate a laser control signal based on characteristics of the detected backscattered radiation, characterized in that
the processor (<NUM>) is operable to generate a laser control signal for selectively enabling and disabling operation of a laser (<NUM>) controlled by the laser controller (<NUM>),
wherein the processor (<NUM>) is operable to generate a laser control signal for disabling operation of a laser (<NUM>) controlled by the laser controller (<NUM>) when the intensity of the detected backscattered radiation is above a cut-off threshold level.