Article

A simple underwater imaging model

Naval Research Laboratory, 1009 Balch Boulevard, Stennis Space Center, Mississippi 39529, USA.
Optics Letters (Impact Factor: 3.18). 10/2009; 34(17):2688-90. DOI: 10.1364/OL.34.002688
Source: PubMed

ABSTRACT It is commonly known that underwater imaging is hindered by both absorption and scattering by particles of various origins. However, evidence also indicates that the turbulence in natural underwater environments can cause severe image-quality degradation. A model is presented to include the effects of both particle and turbulence on underwater optical imaging through optical transfer functions to help quantify the limiting factors under different circumstances. The model utilizes Kolmogorov-type index of refraction power spectra found in the ocean, along with field examples, to demonstrate that optical turbulence can limit imaging resolution by affecting high spatial frequencies. The effects of the path radiance are also discussed.

Download full-text

Full-text

Available from: Weilin Hou, Jul 18, 2014
0 Followers
 · 
180 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: On the basis of the extended Huygens–Fresnel principle, an analytical propagation expression for the elements of the cross-spectral density matrix of a stochastic anisotropic electromagnetic beam through oceanic turbulence is derived. From this formula the spectral density, spectral degree of coherence, spectral degree of polarization, orientation angle and the degree of ellipticity of such a beam on propagation are determined. Some numerical calculations are illustrated relating to the anisotropic electromagnetic Gaussian Schell-model beams propagating through oceanic turbulence. The results indicate that the spectral degree of coherence of stochastic anisotropic electromagnetic beams tends to zero with increasing propagation distance through oceanic turbulence, which is in agreement with results previously reported for turbulent atmosphere. It is also found that the changes in the statistical properties of the anisotropic source on propagation are qualitatively different from those of the isotropic source.
    Applied Physics B 11/2012; 109(2). DOI:10.1007/s00340-012-5173-8 · 1.63 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In order to process underwater imaging to the best possible level, an imaging model based on beam propagation was established. The presented model included not only the laser beam propagation affected by absorption and scattering, but also the effects of underwater turbulence and the diffraction limit of sensors. By this model approximately quantified optical transfer functions (OTFs) were studied. Thus, under this framework, the approaches of image enhancement, restoration and super-resolution reconstruction (SRR) can be extended by incorporating underwater optical properties based on OTF or point spread function (PSF) of the imaging system. Experimental results proved that the imaging range and the image quality can be effectively enhanced, which are critical in underwater imaging or detecting.
    Frontiers of Optoelectronics in China 12/2012; 4(4). DOI:10.1007/s12200-011-0219-9
  • Source
Show more