Single-Frame Chemical Imaging: Dimension Reduction Fiber-Optic Array Improvements and Application to Laser-Induced Breakdown Spectroscopy

A single-frame approach to chemical imaging with high spectroscopic resolution is described that makes use of a second-generation dimension-reduction fiber-optic array. Laser-induced plume images are focused onto a 17 × 32 rectangular array of square close-packed 25 μm cross-sectional f/2 optical fibers that are drawn into a 544 × 1 distal array with serpentine ordering. The 544 × 1 side of the array is imaged with an f/2 spectrograph equipped with a holographic grating and a gated intensified charge-coupled device (ICCD) camera for spectral analysis. Software is used to extract the spatial/spectral information contained in the ICCD images and de-convolute them into wavelength-specific univariate reconstructed images or position-specific spectra that span an 86 nm wavelength space. Temporal resolution is provided by imaging sequential laser plumes with varying time delays after each laser pulse on the gated intensifier.