mounting of these components and the mechanisms for translating them to produce variable magnification are not within the scope of this document. Lens Design Description After redirecting the acoustic signal with a reflector, a system of lenses will image the acoustic signal onto an acoustic sensor. The lenses will be immersed in distilled water which reduces the attenuation of the acoustic signal. All of the lenses will be made of Somos Protogen 18420 plastic which matches the acoustic impedance of water. To change the depth of the object plane, the entire lens system and sensor will be translated along the axis of the probe barrel. To change the field of view and resolution, individual elements of the lens system will be moved relative to each other. The design of the mechanisms for producing these movements is not within the scope of this document. Imaging System Diagram [tbd] Specific Requirements Aperture < f/3 Field 5 mm 40 mm object diam. (22.4 mm primary) – Wavelength 150, 300 (primary), and 450 µm Zoom Range 8x field zoom Sensor Size 22.4 x 1 mm (32 x 1 pixels) Pixel Size 0.7 x 1 mm Nyquist 0.714 lp/mm MTF (as-built) 30 ± 4% across field at 0.5 lp/mm Distortion < 4% Telecentricity n/a Relative Illumination > 90% off-axis; no vignetting Elements ≤ 3 (pending testing) Diameter < 22 mm Length < 500 mm Object Clearance 32 mm from entrance window Image Clearance > 1 cm Airspace Material All airspaces are water immersed
mounting of these components and the mechanisms for translating them to produce variable magnification are not within the scope of this document. Lens Design Description After redirecting the acoustic signal with a reflector, a system of lenses will image the acoustic signal onto an acoustic sensor. The lenses will be immersed in distilled water which reduces the attenuation of the acoustic signal. All of the lenses will be made of Somos Protogen 18420 plastic which matches the acoustic impedance of water. To change the depth of the object plane, the entire lens system and sensor will be translated along the axis of the probe barrel. To change the field of view and resolution, individual elements of the lens system will be moved relative to each other. The design of the mechanisms for producing these movements is not within the scope of this document. Imaging System Diagram [tbd] Specific Requirements Aperture < f/3 Field 5 mm – 40 mm object diam. (22.4 mm primary) Wavelength 150, 300 (primary), and 450 µm Zoom Range 8x field zoom Sensor Size 22.4 x 1 mm (32 x 1 pixels) Pixel Size 0.7 x 1 mm Nyquist 0.714 lp/mm MTF (as-built) 30 ± 4% across field at 0.5 lp/mm Distortion < 4% Telecentricity n/a Relative Illumination > 90% off-axis; no vignetting Elements ≤ 3 (pending testing) Diameter < 22 mm Length < 500 mm Object Clearance 32 mm from entrance window Image Clearance > 1 cm Airspace Material All airspaces are water immersed