Abstract: A method of detecting a chemical species at a stand-off distance using a spectroscopy system, the method comprising the steps of providing a modulated light source emitting a first beam of light at a first wavelength incident to the chemical species, the first beam of light causing the chemical species to emit a signal, providing a spectral shifter a second beam of light at a second wavelength, the second beam of light causing a photochemical reaction in the chemical species to shift a spectrum of the light emitted from the chemical species, providing a detector positioned to detect the signal emitted from the chemical species, and providing a data processor system in communication with at least one of the detector and the modulated light source, the data processor system processing the signal to determine the identity of the chemical species.

Abstract: An apparatus for converting the difference frequency between the transmit lse of a sonar and the return or receive signal from a target to a video representation complementing the audio output of the sonar representing the difference frequency. The audio and complementing video signal indicate the presence of the target and its range. The invention converts the audio signal to a frequency spectrogram by means of digital signal processing including a FFT algorithm. The amplitudes of the frequency components of the audio signal are plotted on the video display of the invention. They are color-coded to indicate the amplitude of the audio signal. The frequency of the audio signal is related to the range of an object detected by the sonar. The invention is mobile and easily managed by a diver.