photomultiplier tube ,its construction ,it's working....... photodiode ,it's construction and working

2. By : MAHROOSH

3. CONTE
NTS
PM DEFINITI
NS
PD
A
PROPER
TIES
PRINCI
PLE
•CONSTRU
CTION
•PHENOME
NAS
•CONSTRU
CTION
•WORKING
•EXAMPLE

4. WORD MEANING :
Photo Light
Multiplier Increase number
DEFINITION :
“It is a photoemissive device in
which absorption of photon results
in emission of electrons”
OR
“It is an electronic vacuum phototube
that converts light into electrical signals”

5. “PMT converts light into
electrical signals,
amplifies that signal to
useful level by
secondary electrons
emission or it is based
upon photoemission

6. Light detection of very weak signals.
Member of class of vacuum phototubes.
Provide ;
current output α light
intensity
Sensitive detector of light in UV, vis, NIR
ranges.

7. CONSTRUCTIO
N
INPUT
WINDO
W e-
OPTIC
AL
INPUT
SYSTE
M
PHOTO
CATHO
DE
ELECTR
ON
MULTIPL
IER
ANODE

8.  INPUT WINDOW
Material limits the spectral sensitivity in short
wavelength region.
 e-OPTICAL INPUT
SYSTEM
Focuses and accelerates all photo-es onto useful
area of first dynode.
 PHOTOCATHODE
Converts light flux into electric flux.
 ELECTRON MULTIPLIER
Consist of series of secondary emission
electrodes.

9. PHOTOEMISSION :
 Absorbed photons impart E to es.
 Energized es diffuse through material
& losing some energy.
 Es reaching surface with sufficient E
escape from it.
SECONDARY EMISSION :
“The phenomenon in which electrons
in vacuum tube are able to cause emission
of additional es by striking an electrode”

14. Array:
“Array is a structure that contains a
group of
discrete elements”
PHOTODIODE:
“It is a semiconductor device
that converts
light into electrical
current”

15. DEFINITION:
“A PDA is a linear
array of
discrete photodiode
on an
integrated circuit (IC)
chip”

16. PDAs are the combo of
photodiodes, so their principle is
:
“Conversion of
light(narrow band
of spectrum) into
electrical

17. Photodiodes
Reversed
biased

18. PROPER
TIES
(photodio
de)
P-
DOPE
D
REGI
ON
CONTAI
N
OPTICA
L
FILTERS
, BUILT-
IN-
LENSES
RESPON
SIVE
TIME α
1/SURFA
CE
AREA
CURREN
T
GENER
ATED α
INCIDEN
T
POWER

19. Source &
sample
Dispersion
device
PD array

20. Source PC beam Sample
Entrance slit
narrow band Dispersion device dispersed
beam PDA