Types of Microscopy Commonly Used for Trace Evidence
Bright field microscopy
Polarizing Light Microscopy (PLM)
Uses standard light to illuminate the field
Polarized Light Microscopy
has a pair of polarizing devices. The first polar (polarizer) defines the initial plane of polarization for light entering the microscope . The other polar (analyzer) defines the plane of polarization of the light reaching the ocular.
Gives good resolving power and optimum contrast
Requires a lamp lens that is capable of being focused, iris diaphragms on both the illuminator and substage condenser, and a substage condenser that can be focused up and down.
Allows for a maximum efficiency of light, angle of illumination and area illuminated
Select your unknown fiber from the table. Tease away a single fiber (a few fibers is fine as long as they are separated), cut it to an appropriate length and place in on your slide.
Place one drop of water directly over the fiber, then place the coverslip on top.
Hold coverslip at a 45o angle w/ edge touching water then let go.
what is trace evidence
glitter, feather,grease,metal,wood chips, shredded paper