Abstract: The disclosed embodiments provide an acoustic deterrent system and a method for repelling sea mammals from a region of water. The system consists of one or more acoustic impulse sources spatially distributed underwater around the perimeter of the fish farm or other region to be protected. Each source is capable of generating an acoustic signal and a controller determines the firing time for each source to produce signals, which may include precisely timed wave trains of superimposed tones on a broadband low frequency signal, which are believed most effective in deterring seals, sea lions and other carnivorous mammals. The system may further include a sensing device to determine the presence of marine mammals so that the acoustic deterrent can be initiated on demand.

Abstract: An assembly is provided for the direct measurement of a vertical intensity profile through a plane of focus along an illuminating beam, a determination of a depth of the focal plane and a maximum intensity of the intensity profile. The assembly includes a plurality of focusing indicia fixed relative to a substrate, the focusing indicia being distributed at different locations along the illuminating beam. The focusing indicia are configured to be illuminated with an intensity corresponding to the position relative to the plane of focus along the axis of the illuminating beam. The location of the respective focusing indicia can be predetermined, such as along a given scale at a given inclination of the scale and the path of the illuminating beam, or not initially known and subsequently determined.

Abstract: An assembly is provided for the direct measurement of a vertical intensity profile through a plane of focus of a confocal microscope, a determination of a depth of the confocal plane and a maximum intensity of the intensity profile. The assembly includes a transparent substrate in which is embedded a scale having a graduated length, wherein the scale is inclined relative to a local portion of an illuminating beam on an illuminating path of the confocal microscope. The graduated scale is configured to be illuminated with an intensity corresponding to the position within the plane of focus along the axis of the illuminating beam. The inclination of the scale and the path of the illuminating beam are at a predetermined angle. The graduated scale can be fluorescently dyed to illuminate with an absorption frequency relevant to a light source or illuminating beam of the confocal microscope. An algorithm employing trigonometric functions and calculating the confocal plane depth of the specimen is disclosed.