Abstract: Measuring systems for making underwater measurements of relative positions and distances between a plurality of objects positioned on an ocean or lake floor basically include (a) at least one laser or other light source capable of projecting a collimated light beam therefrom, (b) a pan and tilt unit for moving the source light beam both angularly in vertical planes and in horizontal arcs, (c) a protractor or equivalent for measuring vertical angles through which the longitudinal axis of the light beam is moved by the pan and tilt unit, and (d) a compass unit for determining bearings of vertical plane positions of the light beam relative to magnetic or true north or other azimuth position. The system may include a plurality of lasers and a variety of methods of making measurements with both single and plural laser containing systems are disclosed.

Abstract: A method for determining position of and/or for positioning an object relative to both (a) its distance to a surface and (b) the orientation of its longitudinal axis to such surface involves emitting in a first plane toward such surface a plurality of first beams of coherent light from a first position adjacent the object so such first plane is at an acute angle relative to the object's longitudinal axis and the first beams of light project forward of the object to cross such longitudinal axis at such acute angle thereby forming on the surface a pattern of the illuminations of the first beams. Simultaneously, second beams are similarly emitted in a second plane toward the surface from a second opposed position adjacent the object to thereby form on the surface a pattern of illuminations of the second beams.

Abstract: Underwater photography apparatus of the type disclosed in U.S. Pat. No. 4,707,094 is improved to overcome problems from backgrounds or other "non-clear water" conditions by inclusion of a nulling loop in the operating circuitry. Such nulling loop includes a synchronous linear modulator, an algebraic subtracter, a synchronous demodulator and a low-pass filter.

Abstract: A laser device for use in submarine service having a window portion through which it emits coherent light has a safety feature that permits coherent light to be emitted through the window portion only when the laser device is immersed in water. In one embodiment, the safety feature involves a pressure switch and in a second embodiment, it involves a shutter float.

Abstract: An underwater visual recording system capable of making consistently in-focus visual records of submarine objects includes a camera having a lens system with a predetermined depth-of-field, a first laser structured to emit a beam of coherent light of a first wavelength range, e.g. green light, a second laser structured to emit a beam of coherent light of a second wavelength range different from the first wavelength range, e.g. red light, and a support that holds the first laser spaced apart from the second laser with the camera therebetween so that the two laser beams project forward of the camera and cross one another within the camera's depth of field. In use of the system, it is positioned so the point of crossing of the laser beams is on the submarine object and then the camera is operated to make a visual recording.

Abstract: Submarine photography apparatus includes a camera to record scenes in a selected sector forward thereof; a source of light having a wavelength in the range between about 650 and 700 nm. designed to project from a position lateral of the camera a conical light beam so that it intersects the sector; and a system of optical and electronic elements to detect and measure the intensity of reflected light from a photographic subject within a conical volume that has its apex lateral of the camera and extends toward the sector to intersect the light beam so that the intersecting peripheries of the light beam and the conical volume substantially define the sector. Methods of photographing with the apparatus include flashing a strobe light and exposing the camera when the system measures an intensity of the reflected light above a predetermined minimum value within the sector.

Abstract: Rotary type knotmeters designed to detect relative motion between an underwater vehicle and the water in which it is submersed at relatively great depths comprise a vaned rotor external unit, an electronic counter/display internal unit, a multiplexing transmission line connecting the external unit to the internal unit and, preferably, a brake unit to stop rotation of the rotor unit when the knotmeter is not immersed in water. The external unit comprises a plurality of spaced Hall-effect magnetic sensors that function with bi-phase electronic detectors to modulate current flowing in the transmission line to power the external unit. Such detectors count the number of rotations per unit time of the vaned rotor which is proportional to the relative motion between vehicle and water. The current is demodulated in the internal unit to produce a velocity value which is then displayed as a digital speed reading.