TEM
Definition
Transmission electron microscope. Electrons pass through an ultra-thin section; resolution below 1 nm. Rare in routine forensic casework, common in research.
- Full name
- Transmission electron microscope
- Mechanism
- Electrons pass through an ultra-thin section
- Resolution
- Below 1 nanometre
- Forensic use
- Rare in routine casework, common in research
Common questions
Why is TEM rarely used in routine forensic casework despite its high resolution?+
TEM requires extensive sample preparation, including cutting ultra-thin sections and often coating or staining, plus specialized equipment and operator expertise, which makes it slow and costly compared to methods like SEM that handle bulkier samples with less preparation and still meet most routine forensic imaging needs.
What forensic sample types would justify using TEM over SEM?+
TEM is better suited to examining internal ultrastructure at the nanometre scale, such as fibre cross-sections, nanoparticle characterization, or certain gunshot residue or paint-layer studies where sub-nanometre internal detail is needed, situations SEM's surface-imaging strength cannot address.
Related terms
- Comparison Microscope
- Two compound microscope bodies connected by an optical bridge that presents one half of each body's image in a single split eyepiece...
- Depth of Field
- Axial thickness of the specimen that appears acceptably in focus at one time. High in stereoscopic microscopes, very low in oil-immersion compound...
- EDX / EDXRF
- Energy-dispersive X-ray detector attached to an SEM. Identifies elements from characteristic X-rays emitted when the beam strikes the sample. Backbone of GSR...
- Fluorescence Microscope
- Uses UV or short-wavelength excitation to make fluorophores emit longer-wavelength light. Used for semen, saliva, fibres and ink discrimination.
- Numerical Aperture (NA)
- The product of the refractive index of the medium between objective and specimen and the sine of the half-angle of the maximum...
- Polarising Microscope
- Compound microscope fitted with a polariser below and an analyser above the stage. Used to study birefringent materials like fibres, minerals and...
- Resolution
- The ability of a mass analyser to distinguish two ions of nearly equal m/z, defined as m/Δm at a given peak. A...
- SEM
- Scanning electron microscope. Focused electron beam raster-scans the sample surface; resolution down to a few nanometres with great depth of field. Paired...
- Stereoscopic Microscope
- Two separate light paths producing a true 3D image at low magnification (typically 7x to 40x). Used for trace recovery, gross examination...