This course introduces students to the principles and practical use of the stereomicroscope and polarized light microscope for the analysis of common microscopic trace evidence (hairs, fibers, paint, and glass). In addition to beginning theory of polarized light microscopy (PLM), the student learns the basic techniques of PLM directly applicable to trace evidence analysis.
Forensic Trace Evidence
- Applications and versatility of the light microscope
- Principles of stereomicroscopy, including illumination techniques and magnification determinations
- Manipulation and preliminary examination of trace evidence, including techniques for counting, measuring, isolating, mounting, and recording particles
- Preliminary analysis and preparation of a miscellaneous trace evidence mixture including paint chips
- Mechanical and optical alignment of the Olympus BX51 polarized light microscope (PLM)
- Using the PLM to make measurements (micrometry), and calibration of the ocular micrometer
- Using particle morphology to characterize and identify trace evidence
- Analysis of human hair, animal hair, and natural fibers
- Principles of plane polarized light, including refractive index measurements, pleochroism, contrast phenomena, and dispersion staining
- Analysis of glass particles and glass look-alikes
- Principles of crossed polarized light, including isotropy and anisotropy, extinction angles, retardation, and birefringence determinations using the Michel-Lévy interference color chart
- The use of compensators and how to determine sign of elongation
- Analysis of synthetic fibers
- Integration of microscopical methods as applied to trace evidence analysis and the identification of practice samples
- Report writing and court testimony
Upon satisfactory completion of this course, the student will:
- Use a stereomicroscope for the initial examination of trace evidence
- Perform general trace evidence sample preparation
- Skillfully operate a polarized light microscope to obtain optical data for samples in question
- Employ the theory and techniques of polarized light microscopy to the analysis of trace evidence
- Observe, interpret, and record optical data obtained using light microscopy
- Examine, characterize, and identify trace evidence commonly encountered in the crime lab
- Inexperienced forensic scientists and criminalists with new responsibilities for trace evidence analysis
- Newly assigned trace evidence examiners
All instrumentation, materials, and supplies necessary for successful completion of this course will be provided onsite by Hooke College of Applied Sciences.
- Detailed course manual
- Essentials of Polarized Light Microscopy and Ancillary Techniques by John Gustav Delly
- Olympus BX51 microscope with polarized light capabilities
- Olympus stereomicroscope
- The McCrone Atlas of Microscopic Particles, a free online reference aid to substance identification
- Modern Microscopy, a free, peer-reviewed online journal for the professional microscopist
None. This course is designed as a basic introduction to microscopy and trace evidence analysis.
Students are expected to successfully complete a variety of tasks in the form of hands-on exercises, laboratory exercises, identifications of unknowns, and quizzes. Students are notified at the end of the course whether or not they have successfully completed the requirements of the course based on:
- 100% Attendance
- Class participation
- Completion of all course material
- Completed and signed student evaluation form
Upon successfully meeting these requirements, a student is awarded a certificate of completion and CEU credits, if available. Those who have not successfully passed the course requirements do not receive a certificate or CEU credits.
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