BACKGROUND

Optical systems have a wide variety of applications, such as range finding, target designation, and active illumination. A range finding optical system typically determines distance to a target by emitting a laser pulse and collecting energy reflected from that target. For example, a range finding system can determine the time difference between emission of the laser pulse and collection of the reflected energy, and translate that time difference into a distance (range) to the target. Such systems can use the Doppler Effect to judge whether the target is moving away from or towards the range finding system. In target designation, the system illuminates a target for a non-collocated receiver (e.g., another system some distance away). Target designation and range finding systems typically require a narrow laser field of view to maximize range. In particular, the field of view can be affected by the closest operational range requirement and the pointing accuracy of the optical system. In contrast, active illumination systems typically require a wide field of view. Active illumination systems use reflected short wave infrared (hereinafter “SWIR”) light to image a scene. For example, in many instances there is an absence of light necessary to properly view a target (e.g., at night or when the target is inside caves, tunnels, enclosed buildings, etc.). Instead of illuminating the target with light that is detectable by the human eye, active illumination systems emit an SWIR laser pulse, and collect energy reflected from the target and the surrounding environment. The reflected energy is used to construct a visual representation of the target and the surrounding area. As such, in an active illumination optical system it is advantageous to have a wide field of view.

SUMMARY OF INVENTION

Aspects and embodiments are directed to optical systems and methods for supporting range finding, target designation, and active illumination capabilities. In particular, aspects and embodiments are directed to a controllable optical phased array having continuous adjustable focus and defocus capabilities.

According to various aspects and embodiments, an electro-optical sighting system is provided. The system includes a first optical transmitter configured to emit an infrared beam along an optical path toward a target, a beam director positioned in the optical path and having a plurality of optical elements configured to direct the infrared beam and to collect reflected infrared radiation from reflection of the beam from the target, a focal plane array detector configured to receive collected reflected infrared radiation from the beam director, an optical phased array positioned in the optical path between the first optical transmitter and the beam director; and a controller operatively coupled to the optical phased array and configured to direct the optical phased array to defocus the infrared beam to broaden a field of view of the first optical transmitter for active illumination, and focus the infrared beam to narrow the field of view of the first optical transmitter for range determination and/or target designation.

In one embodiment, the system further includes a beam splitter configured to direct the reflected infrared radiation collected by the beam director onto the focal plane array detector. In a further embodiment, the controller is coupled to the focal plane array detector and further configured to generate images of a scene including the target from the reflected infrared radiation directed onto the focal plane array detector. In another embodiment, the controller is further configured to direct the optical phased array to defocus the infrared beam to broaden the field of view of the first optical transmitter, and focus the infrared beam to narrow the field of view in response to analysis of the generated images of a scene including the target. In another embodiment, the controller is further configured to direct the optical phased array to defocus the infrared beam to broaden the field of view of the first optical transmitter, and focus the infrared beam to narrow the field of view in response to receiving external input from one or more external sources.

In one embodiment, first optical transmitter includes a short wave infrared active illumination laser. In a further embodiment, the focal plane array detector is configured to sense light in a wavelength range of 1.0 μm to 2.0 μm. In one embodiment, the system further includes a second optical transmitter configured to emit a second infrared beam along the optical path. In a further embodiment, the second optical transmitter includes a target designation laser. In another embodiment, the second optical transmitter includes a range finding laser.

In one embodiment, the controller further comprises a user interface configured to receive a user focus command to defocus the infrared beam to broaden the field of view of the first optical transmitter, and to focus the infrared illumination beam to narrow the field of view of the first optical transmitter.

According to another aspect, a method of operating an electro-optical sighting system is provided. The method can include the acts of emitting an infrared beam from a first optical transmitter along an optical path through an optical phased array toward a target, focusing the infrared beam onto the target with the optical phased array to define a first field of view of the first optical transmitter, receiving reflected infrared radiation from reflection of the beam from the target at a focal plane array, and responsive to receiving reflected infrared radiation, re-focusing the infrared beam with the optical phased array onto the target to define a second field of view of the first optical transmitter.

In one embodiment, the method can further include the act of receiving external input from one or more external sources. In a further embodiment, the method can further include the act of re-focusing the infrared beam with the optical phased array onto the target to define a second field of view of the first optical transmitter responsive to receiving external input.

In one embodiment, the first optical transmitter includes an active illumination laser, and re-focusing the infrared beam with the optical phased array onto the target further includes broadening the first field of view to increase active illumination of the target by the infrared beam.

In one embodiment, first optical transmitter includes a target designation laser, and re-focusing the infrared beam with the optical phased array onto the target further includes ascertaining an infrared beam target indicator size and maintaining the infrared beam target indicator size.

In accordance with one embodiment, the first optical transmitter includes a range finding laser, and re-focusing the infrared beam with the optical phased array onto the target further includes narrowing the first field of view to maximize emission distance of the infrared beam.

In a further embodiment, the method can further include the act of emitting a second infrared beam from a second optical transmitter along the optical path through the optical phased array toward the target.

Still other aspects, embodiments, and advantages of these exemplary aspects and embodiments are discussed in detail below. Embodiments disclosed herein may be combined with other embodiments in any manner consistent with at least one of the principles disclosed herein, and references to “an embodiment,” “some embodiments,” “an alternate embodiment,” “various embodiments,” “one embodiment” or the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described may be included in at least one embodiment. The appearances of such terms herein are not necessarily all referring to the same embodiment.

