Maintenance and Calibration
As in the case of the stereomicroscope, the Association of Firearm and Tool Mark Examiners (AFTE) provides its members with a set of standard techniques for the maintenance and calibration of comparison microscopes. While these techniques are not mandatory (unless stated in individual laboratory policy), they may be used to satisfy the requirements of accreditation standards.
The standards are as follows:
- The comparison microscope will be cleaned, serviced, and certified (by a factory certified technician).
- These steps will be documented in the instrument’s maintenance/calibration logbook.
- The comparison microscope will be calibrated with a glass slide with 0.04” ruled to 0.001”.
- The slide should have a NIST traceable certificate.
- This will be documented in the instrument’s maintenance/calibration logbook.
- For each use:
- The comparison microscope will be checked to ensure that it is functioning properly.
- This check will be performed by placing two similar items on each stage (test to test) and observing the agreement between these items. This would be documented in the examiner’s case notes.