GRIM3 -an advanced workstation for the forensic examination of glass using the refractive index (RI) temperature variation method.

Features:

• Multiple RI measurements for greater efficiency
• Improved temperature stability
• Enhanced casework documentation
• Network facilities for remote supervision
• Windows2000 and XP in a choice of languages
• Data export facilities

Superseding GRIM2 the new workstation retains the widely accepted laboratory technique of glass RI determination, the oil immersion/temperature variation method. The system operates through a standard laboratory microscope with phase contrast optics and a Mettler hotstage, for temperature control. By varying temperature to alter the refractive index of a calibrated oil, the RI of an immersed fragment of glass can be determined at the point of null refraction, the point at which the refractive indices of glass and oil match. Using GRIM3, repeat measurements produce results with a standard deviation of, typically, 0.00002RI over a 5 hour period and 0.00003RI over a 5 day period.

Multiple glass edge processing
The use of new high-speed processors enables GRIM3 to monitor up to four glass fragment edges per operation. The four image- processing windows, adjustable for size and shape, may be positioned independently, allowing the operator to select the best edges and avoid impurities. With four null point temperature measurements per run, the number of runs required to provide an acceptable level of statistical accuracy is greatly reduced, speeding the casework examination process as well as reducing immersion oil calibration time.

Comprehensive casework database
GRIM3 ensures that casework results cannot be filed without the essential information that identifies each fragment of glass examined, including its source and casework reference, and the identity of the operator. All filed results are password protected. Basic statistics are generated including average, range, spread and standard deviation. Results may be displayed as scatter diagrams and formatted for exportation to Microsoft Office for additional analysis.

GRIM3 can also be accessed remotely through networking facilities, allowing casework reviews to be conducted by laboratory supervisors or reporting officers without interrupting operators.

Calibration
Easy to follow procedures enable immersion oils to be calibrated with up to 12 glass standards. GRIM3 automatically constructs a linear temperature versus RI conversion formula for each oil and calculates the correlation coefficient to quantify its accuracy. Calibration data for any number of oils and wavelengths may be stored and are password protected. Re-calibration may be undertaken at any time.

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