L11: FORENSIC EXAMINATION OF ALTERED DOCUMENTS Flashcards
1
Q
what’s ESDA stand for
A
Electrostatic Detection Apparatus
2
Q
when was ESDA invented?
A
1970’s
3
Q
what does ESDA do?
A
shows impressions on documents.
4
Q
what type of sheet is used in ESDA?
A
mylar sheet
5
Q
what can ESDA also detect?
A
finger prints
6
Q
what does the success of ESDA also depend on?
A
humidity
time after applying toner
7
Q
How is ESDA carried out?
A
- humid environment
- document upwards, suction
- mylar sheet on top
- mylar exposed to ionised air
- mylar selectively charged where indentations
- wait
- scatter black toner powder
- impression is black
- protect clear adhesive
8
Q
what’s our visible range ?
A
400-700nm
9
Q
what the IR spectrum range?
A
700-1000nm
10
Q
What does IR absorption allow us to detect?
A
distinguish chemically different inks use to their absorbance range
11
Q
IR absorption can reveal _____ _____
A
obliterated writing
12
Q
what is tungsten light?
A
visible + near-IR
13
Q
what colour will IR absorption images appear ?
A
black, grey or even vanish
14
Q
what’s a soft UV light?
A
365 nm
15
Q
what’s a medium range for UV?
A
313 nm
