Transcript Investigation and Design of Wide Dynamic Range Gating

GATED OPTICAL SENSORS
Pavlo Molchanov1 ,
Vincent M. Contarino2,
Olha Asmolova1
1AMPAC
Inc., USA,
[email protected];
2Naval Air Systems Command Research and
Engineering Group, Patuxent River, MD,
USA, 20670-1161;
LASER IMAGING SYSTEM
UNGATED
SENSOR
AREA OF
OBSERVATION
SHORT LASER
PULSE
MEDIA
MEDIA
LASER
GATED OPTICAL
SENSOR
SIGNAL OF
OPTICAL SENSOR
MEDIA REFLECTED LIGHT
ATTENUATION
30-40 dB
ATTENUATION
30-40 dB
GATED
SENSOR
PULSE
WIDTH
TIME
GATED OPTICAL SENSORS
Gated Photodetectors,
or One point optical sensors
Hamamatsu (8 mm.
diameter active area)
photomultiplier tube
R7400U series
Gated Cameras
or Imaging optical sensors
Gating photomultiplier tube with large resistance
photocathode and three controlled dynodes (M10)
PC
Optimal
Regime
Gate
Closed
-450
-450
-60
D1
-420
-470
D3
-390
-330
-60
D5
-210
-390
-
-60
-400
- +70
-330
-60
+130
-270
-420
-60
-10
-60
D4
+50
+80
-390
-60
-60
-20
-60
D2
Gate
Open
Pulse
-270
-270
-60
-10
-280
+130
-
+70
-210
Photosensitive Module M8
M8.1
AR1
LM317 R23
240
S4
100V
H7400U with large
resistance semitransparent
bialkali photocathode
+
R10
47k
R11
47k
R22
5K
TP2535
AR1
LM317 R1
240
R7
50
S1
100V
-
R8
240
C2
0.1n
R3
1K
R4
1K
C3
0.1n
PC
R5
1M
D1
R6
1M
D2
+
C1
0.1n
R2
5K
AR2
LM317
C4
0.1n
R12
200K
S2
R7 +
600V
50
R13
100K
R9
5K
D3
D4
Board1
AR3
LM317 R20
240
Board 2
R15
100K
R16
100K
D5
D6
D7
R17
47K
S3
100V
+
R18
100K
DC
R21
5K
R14
100K
R19
50
D8
P
Schematic of gated power supply with two gated transistors,
H5900U, H7600U, (LS2.1)
LS1.3
AR1
LM317 R24
240
Negative Bias
-
S2
100V
+
TP0620N3
R13
5K
AR1 R17
LM317 240
R14
50
Gate Pulse
-
S1
200V
R18
5K
R15
1K
C2
0.1n
C3
0.1n
+
TN0620N3
PC
R1
200K
R16
1K
R24
50
AR2
LM317 R19
240
C1
0.1n
C4
0.1n
R3
1M
D1
R2
10K
D2
C5
0.1n
R4
200K
C6
0.1n
R6
10K
R5
1M
C7
0.1n
D3
Gain
-
C8
0.1n
R7
1M
S3
R7
800V +
50
R8
200K
R20
5K
Board1
R9
100K
C10
0.1n
R10
100K
C11
0.1n
C12
0.1n
Board 2
D4
C9
0.1n
D5
D6
D7
D8
D9
AR3
LM317 R21
240
Saturation
R11
47K
S4
200V
+
R12
100K
DC
R22
5K
R23
50
C13
0.1n
D10
C14
0.1n
P
Experimental setup for investigation gated photodetector in
pulse regime
Oscilloscope
ND Lens
Filter
Mirror
Pulse Laser
Photodetector
Module
90%
Laser Power
Supply
10%
DC Power
Supply
Synchronization Circuit
B
Pulse Generator
BNC Model555
A
C
Gate
Open
Input Signal
Gate
Closed
10nsec
Setting time 40 nsec for 99%
Gate
Open
Gating rise time 10 nsec
40nsec
Input Signal
Output Signal
M8,
H7400U
Gate
Closed
Gate Open
Gate Closed
Input signal
2mV
Output signal
Attenuation in Closed
State 30 dB of Optical
power
Gate Open
ND=3
Gate Closed
Input signal
2mV
Output signal
M8, H7400U
ND=6
M8
10000
Dynamic Range
Of Optical Power
100
50 DB
A,mV
1000
10
1
7
6
5
4
3
2
1
0
ND
Dyn, #1
3500
50 dB
3000
2500
Out, mV
2000
Out, mV
1500
1000
500
M7
0
0.01
0.1
1
10
Popt, nW
100
1000
10000
M8
A, mV
Underwater Target Detection
Reflected
signal
intensity
Region of observation
Gate
open
Gate
closed
Gate
closed
Time
(nsec)
Reflected
from surface
signal
Reflected
from target
signal
Target
-protection from ocean surface reflected laser beam;
-protection from sunburst reflections;
-decreasing of noise background.
SeaTROLL mounted on the bow of R/V New Horizon
during field test
[Fully assembled SeaTROLL system mounted on rails
and extended out over bow of ship]
Application of Gated IR camera in Fire LIDAR
Regular Camera
Gated IR camera
GATED OPTICAL SENSORS
Gating Pulse
width
1-10
Nano second
Area of
observation
(resolution)
0.3 – 3
meter
1
Pico second
1
Femto second
0.3
millimeter
0.3
micrometer
Application
Underwater
measurements,
Target detection
Human body
screening
Biomedical
microscopy,
tomography