초록 ▼

A novel system for remote detection and imaging of underwater objects is presented. In accordance with the present invention, a laser is used to generate short pulses of light with pulse widths on the order of nanoseconds. The laser light is expanded by optics and projected down towards the surface

A novel system for remote detection and imaging of underwater objects is presented. In accordance with the present invention, a laser is used to generate short pulses of light with pulse widths on the order of nanoseconds. The laser light is expanded by optics and projected down towards the surface of the water and to an object. Intensified CCD (charge coupled device) cameras (preferably two) are electronically shuttered after the time delay corresponding to the round trip propagation time and from to the object. This timing eliminates light scattered by the water from in front of and behind the object. As a result, the veiling luminance of the water is greatly attenuated and faint target signatures can be seen. The resulting gated images (displayed on a CRT) have sufficient spatial resolution to classify and/or identify the object. The imaging lidar system of the present invention takes advantage of the fact that all opaque targets will cast a shadow. The exposure of the two cameras in the system are timed such that one camera gives an image of the object against the backscattered light from the water while the other camera gives an image of the shadow of the object against the backscattered light. These two images are then subtracted to improve the detectability of the object.

대표청구항 ▼

A method of detecting and imaging an object enveloped by a backscattering medium which is at least partially transmitting to light including the steps of: selectively generating short pulses of light; projecting said short pulses of light toward the backscattering medium and at an object enveloped b

A method of detecting and imaging an object enveloped by a backscattering medium which is at least partially transmitting to light including the steps of: selectively generating short pulses of light; projecting said short pulses of light toward the backscattering medium and at an object enveloped by the medium; detecting said pulses of light reflected back from said object after a time delay corresponding to the round-trip propagation time of said light pulses to and from said object; and converting said detected pulses of light to a video image of said object; wherein said step of detecting said reflected pulses of light further comprises the steps of; detecting a first image of the object against the backscattered light from the backscattering medium; detecting a second image of the shadow of the object against the backscattered light from the backscattering medium; and subtracting the first image from the second image to improve detectability and imaging of the object.