초록

An optical atomic resonance filter using two pump lasers, a buffer gas and magnesium as an atomic vapor converts underwater signals in the Fraunhofer wavelengths in the green portion of the spectrum to UV light which is readily detectable by conventional photomultiplier tubes.

대표청구항 ▼

A method for communicating through seawater at a wavelength l1 comprising of steps of: a. transmitting light at a wavelength l1 centered at a Fraunhofer line in the blue-green portion of the spectrum; b. providing a first optical filter having an optical transmission wavelength greater than a first

A method for communicating through seawater at a wavelength l1 comprising of steps of: a. transmitting light at a wavelength l1 centered at a Fraunhofer line in the blue-green portion of the spectrum; b. providing a first optical filter having an optical transmission wavelength greater than a first cutoff wavelength lc1, where l1>lc1; c. providing a second optical filter spaced apart from the first optical filter and having an optical transmission wavelength less than a second cutoff wavelength lc2, where lc2lc1; d. providing magnesium vapor positioned between and adjacent to the first and second optical filters; e. providing a buffer gas positioned between and adjacent to the first and second optical filters wherein the buffer gas is a noble gas; f. pumping the atomic vapor to a first excited state from which light can be absorbed at a narrowband wavelength centered at a Fraunhofer line l1, wherein l1 is 516.733 nm, 517.270 nm or 518.362 nm, thereby raising the atomic vapor to a second excited state; g. pumping the atomic vapor to a third excited state, whereby collisions with the buffer gas raise the atomic vapor to a fourth excited state, the atomic vapor at the fourth excited state exhibiting a fluorescence transition to the second excited state by emission of light at a fluorescence wavelength l2, where l2lc2 and where l2 is in the near UV portion of the spectrum and whereby light at the absorption wavelength l1 incident on the first optical filter is transformed to light at the fluorescence wavelength l2 and emitted through the second optical filter; h. detecting light at the fluorescence wavelength l2 emitted through the second optical filter.