COMPACT RAMAN SPECTROGRAPH WITH FIBER OPTIC SAMPLING

THE OVERALL OBJECTIVE OF THIS PROGRAM IS TO DEVELOP A RAMAN SPECTROGRAPH FOR DETECTION AND IDENTFICATION OF CHEMICAL/BIOLOGICAL CONTAMINATION ON SURFACES, AND WHICH CAN BE ENGINEERED AS A FIELD HARDENED, COMPACT, LIGHTWEIGHT PORTABLE SYSTEM. THE PROPOSED SPECTROGRAPH WILL PERMIT A FULL (4000/CM) RAMAN SPECTRUM OF A SOLID, LIQUID OR GASEOUS SAMPLE TO BE OBTAINED IN A SINGLE RAPID MEASUREMENT WITHOUT INTERNAL MOVING PARTS OR CALIBRATION, SUCH AS ADJUSTMENT OF SLITS OR GRATINGS. THE DESIGN GOAL IS FOR LESS THAN 1/CM RESOLUTION. IN ITS FULLY DEVELOPED FORM, THE SPECTROGRAPH LASER USED FOR RAMAN EXCITATION, DETECTOR AND COMPUTER WILL BE MAN-PORTABLE. TO ACHIEVE THIS DEGREE OF PORTABILITY, A SMALL HIGH RESOLUTION ECHELLE SPECTROGRAPH HAS BEEN DESIGNED WHICH WILL INCORPORATE A SOLID STATE MICROLASER FOR EXCITATION AND A WIDE FORMAT TWO-DIMENSIONAL CHARGE COUPLED DEVICE (CCD) ARRAY FOR DETECTION. THE INSTRUMENT WILL ALSO EMPLOY A FIBER OPTIC PROBE FOR SAMPLING, WHICH WILL BE PARTICULARLY SUITABLE FOR SCANNING CONTAMINATED SURFACES AND INACCESSIBLE LOCATIONS. THE PROBE INCORPORATES A MICRO-OPTICAL TERMINATING HEAD CONTAINING FILTERS FOR REMOVAL OF SILICA FIBER RAMAN SCATTERING FROM THE SIGNAL. THE GOAL OF PHASE I IS TO CONSTRUCT AND CHARACTERIZE THE SPECTROGRAPH FOR OPERATION WITH CCD DETECTION AND SOLID STATE MICROLASER EXCITATION, AND TO EVALUATE IT FOR DETECTING SEVERAL AGENT SIMULANTS AS NEAT SAMPLES AND DISPERSED ONTO SUFACES WITH SEVERAL DIFFERENT OPTICAL BACKSCATTERING PROPERTIES AT CONCENTRATIONS LESS THAN OR EQUAL TO 1G/M2.