Subject to local technical requirements and requlations, availability of products included in this promotional material may vary. Please consult with our sales office.
Information furnished by HAMAMATSU is believed to be reliable. However, no responsibility is assumed for possible inaccuracies or omissions.
Specifications are subject to change without notice. No patent rights are granted to any of the circuits described herein. 1997 Hamamatsu Photonics K.K.
Capturing still images of high-speed phenomena!
FEATURES
High-speed gating : Gate time .......................... 3ns
Repetition frequency ....... 30kHz
Gate time and delay time digitally set to 100ms
Gate time and delay time can be precisely set (50ps steps)
RS-232C interface allows external control of all functions
High sensitivity nearly equal to photon counting imaging
levels (C7245 using a two-stage MCP image intensifier)
Wide spectral response from UV to near infrared
Standard type:115 to 840nm
Infrared extended type: 350 to 910nm (manufactured upon
your request)
Low image distortion (proximity-focused image intensifier)
Built-in excessive light protection circuit
Large shutter ratio (
1.6
~
10
10
)
APPLICATIONS
Analysis of high-speed light emission
Fuel combustion in engines
Plasma
Discharge
Fluorescence
Low-light-level imaging and measurement
Microscopy
Bioluminescence, chemiluminescence
Two-dimensional spectroscopy
Observation of high-speed moving objects
Turbine blade motion
Exploding events
Ink jet operation
HIGH-SPEED GATED
IMAGE INTENSIFIER UNITS
C7244, C7245
The Hamamatsu C7244 and C7245 are high-speed gated image intensifier units developed specifically for imaging of high-
speed phenomena occurring at low light levels. These image intensifier units consist of an image intensifier head and its control-
ler with a built-in high voltage power supply. The image intensifier head easily connects to the front of a CCD camera to config-
ure a high-speed shutter camera that allows capturing still images of high-speed phenomena at any desired timing. The C7244
and C7245 for example, can be used to observe temporal changes in bioluminescence and discharge events, as well as
measurements of various high-speed phenomena. Moreover, when used for fluorescence observation, the gate function elimi-
nates the primary excitation light to allow imaging of short lifetime fluorescent light without being affected by the primary light.
All the C7244 and C7245 functions are computer-controllable, for compatibility with many kinds of measurement applications.
C-mount adapter is optional.
HIGH-SPEED GATED IMAGE INTENSIFIER UNITS C7244, C7245
2
GATE OPERATION
Gating
To capture and analyze the image of a fast moving object or
light emissions changing at a high speed, the imaging device
must have a shutter speed higher than those events. How-
ever, as shutter speed increases, the amount of incident light
is unavoidably reduced, so higher sensitivity is required of
this type of imaging devices. The "gate operation" of an
image intensifier is effective in solving these two contradic-
tory problems at the same time. The gating electronically
switches the image intensifier to operate it only for the
required time duration, making it possible to intensify and
read out the desired image of an object or event changing at
a high speed.
The Hamamatsu C7244 and C7245 enable high-speed gated
imaging by simply supplying a trigger pulse. The gate time
can be set from 3ns to 100ms in fine steps of 50ps. A high-
speed shutter camera can be readily configured by connect-
ing the image intensifier head to a CCD camera. The image
intensifier used is compact yet provide very high image
intensification (gain) and therefore compensate for the
reduced amount of light concurrent with the shortening of the
gate (shutter) time. This makes it possible to capture and
analyze still images of a high-speed phenomenon taking
place at low light levels.
Configuration and Operating Principle
The C7244 and C7245 high-speed gated image intensifier
units consist of an image intensifier head and a controller.
The head incorporates a proximity-focus image intensifier
along with a gate drive circuit. The controller includes a high-
voltage power supply, interface circuit and timing circuit.
The gate drive circuit in the head keeps the image intensifier
"normally OFF" and turns ON when a gate pulse is input.
With the mode switch set to the gate side, supplying a gate
trigger pulse allows operation of the image intensifier only
for the gate time specified, as shown in Figure 1.
The maximum repetition frequency of the gate trigger pulse
is 30kHz. If the repetition frequency exceeds 30kHz or the
gate time overlaps the next trigger time, the built-in control
circuit functions to prevent gate operation.
When the mode switch is set to the normal side, it serves as
a normal image intensifier, regardless of gate signal input.
In addition, trigger level setting, image intensifier gain and
gate time can all be controlled by a computer through the
RS-232C interface.
Figure 1: Time Sequence
Figure 2: Gate Operating Range
GATE SIGNAL INPUT PULSE
TRIGGER LEVEL
Tg
Ti
20ns
100ns
CLOSE
CLOSE
GATE OPEN
JITTER : <150ps
FWHM
TIME
Td>75
2ns
GATING (I.I.)
GATE TIME MONITOR
GATE TIME MONITOR
Ti
Tg
Td
: GATE TRIGGER INPUT PULSE WIDTH = 3 ns MIN.
: OUTPUT GATE TIME = 3 ns to 100 ms
: DELAY TIME
10
-10
10
-9
10
-8
10
-7
10
-6
10
-5
10
-3
10
-4
10
-3
10
-1
10
1
10
3
10
5
GATE REPETITION FREQUENCY (Hz)
OUTPUT GATE TIME (s)
3
10
-9
s MIN.
3
10
4
Hz MAX.
TAPPC0067EA
TAPPB0063EA
3
Figure 3: Block Diagram
RATINGS AND SPECIFICATIONS
Parameter
Operation Mode
Normal Mode
Continuous
Gate Mode
Normally OFF, ON when gate signal input
Gate Trigger Signal Input
Level
-5V to +5V
Input Impedance
50
Pulse Width
3ns Min.
Repetition Frequency
30kHz Max. (with limiting circuit)
Gate OFF Time
20 s Min. (with internal limiting circuit)
Gate Output
3ns to 10ms (50ps steps):
with internal control circuit
Gate Time
3ns to 100ms (50ps steps):
with external control circuit
Gate Rise Time
2ns Typ.
Gate Fall Time
3ns Typ.
75ns to 10ms (50ps steps):
with internal control circuit
Delay Time
75ns to 100ms (50ps steps):
with external control circuit
Gate Jitter
150ps Max.
Gate Time Monitor (Rear Panel)
Output Level
1.0V, positive logic
Pulse Width
Gate time width
Output Impedance
50
Gate Time Display
Gate Time/Delay Time
Switchable (front panel)
Display
7-segment display, 9 digits (10ps to 10ms)
Trigger Output
Level
TTL, positive logic
Width
100ns Typ.
Delay Time (with respect to trigger) *
20ns Typ.
Parameter
Protect Monitor: LED lights up in the following states
Gate Repetition Frequency
Higher than 30kHz
Minimum Gate OFF Time
Less than 20s
Excessive Light Protection Phosphor screen luminance: more than 20cd/m
2
Gate Inoperative Range
When the gate time overlaps the next trigger time
External Control Specifications (RS-232C)
Image Intensifier Gain (Setting/Monitor)
8 bits
Trigger Level (Setting/Monitor)
8 bits (-5V to +5V)
Gate Width Setting
3ns to 100ms (50ps steps)
Gate Delay Time Setting
20ns to 100ms (50ps steps)
Image Intensifier Power Supply
ON/OFF
Mode Selection
Gate/Normal
Slow Motion Operation
Automatic delay control for gate pulse,
Image readout cycle setting (VD signal input)
RS-232C
D-sub 9 pin
I.I.: Image Intensifier
General Specifications
Weight
3.7kg
(including head: 300g)
Ambient Operating Temperature
0 to +40C
Ambient Storage Temperature
-25 to +60C
Power Requirement
90 to 250Vac, 47 to 63Hz
Power Consumption
40VA
* The maximum gate time at 30kHz gate repetition frequency is 13s.
90 TO 250Vac
VD INPUT
HV/POWER
CONNECTOR
GAIN
ADJUSTMENT
DIAL
OVEREXPOSURE
DISPLAY LED
IMAGE INTENSIFIER
GATE DRIVING CIRCUIT
CONTROL MODE SWITCH
HEAD SECTION
POWER SUPPLY
SECTION
DISPLAY SWITCH
ERROR/TRIGGER DISPLAY LED
TRIGGER POLARITY SWITCH
TRIGGER LEVEL DIAL
TRIGGER INPUT
MODE SWITCH
TRIGGER OUTPUT
RS-232C INTERFACE
CONNECTOR
HIGH-
VOLTAGE
POWER
SUPPLY
DELAY/GATE TIME
DISPLAY SECTION
GATE CONTROL
CIRCUIT
INTERFACE CIRCUIT
POWER
SUPPLY
CIRCUIT
OVEREXPOSURE
PROTECTION
CIRCUIT
TAPPC0068EA
HIGH-SPEED GATED IMAGE INTENSIFIER UNITS C7244, C7245
4
BUILT-IN IMAGE INTENSIFIER CHARACTERISTICS
Figure 4: Typical Spectral Response
Figure 5: Typical Linearity
Figure 6: Typical Luminous Emittance Gain
Typical EBI (Equivalent Background Input) Characteristics
C7244
C7245
G =
Lo
Ei
Parameter
Luminous Sensitivity
Radiant Sensitivity
(430 nm)
Quantum Efficiency
(400 nm)
Photocathode
Window Material
Effective Diameter
Window Material
Phosphor Material
Afterglow Time
Luminous Emittance Gain (Fig. 6)
(Gain Max.)
a
Radiant Emittance Gain (Fig. 7)
(Gain Max.)
Luminous (Fig. 6)
Radiant (Fig. 7)
(430nm)
Limiting Resolution (Fig. 10)
(MTF)
Magnification
Maximum Input Radiance
(Normal Mode, Gain Max.)
Average of Max. Phosphor
P-43
Screen Luminance (Gate Mode)
C7244
C7245
200
47
14
Synthetic Silica
17.5
Fiber Optic Plate
P-43
See Fig. 12.
7
10
3
1
10
6
5.5
10
3
5.5
10
5
4
10
-11
4
10
-11
1
10
-13
1
10
-13
30
25
1
5.4
10
-3
1.6
10
-5
8
10
-10
2.4
10
-12
10
Unit
A/lm(Typ.)
mA/W(Typ.)
%(Typ.)
mm
(Min.)
W/m
2
/W/m
2
(Min.)
lm/cm
2
(Max.)
W/cm
2
(Typ.)
lp/mm
(Min.)
lx
W/cm
2
at 550nm
cd/m
2
Cathode
Sensitivity
Phosphor
Screen
EBI
(Gain Max.)
10
-1
10
3
10
1
10
-3
10
-5
10
-10
10
-8
10
-6
10
-4
10
-2
10
0
INPUT ILLUMINANCE (lx)
PHOSPHOR SCREEN LUMINANCE (lm/m
2
)
G=7
10
3
G=1
10
6
10
4
10
3
10
2
10
1
0
5
10
LUMINOUS GAIN (lm/m
2
/lx)
LUMINOUS GAIN
EBI
10
-9
10
-10
10
-11
10
-12
EBI (lm/cm
2
)
DIAL SETTING
10
5
10
4
10
2
0
5
10
10
7
10
-7
10
6
10
-8
10
-9
10
-10
10
3
10
-11
10
-12
EBI (lm/cm
2
)
DIAL SETTING
LUMINOUS GAIN (lm/m
2
/lx)
LUMINOUS GAIN
EBI
TII B0020EA
TAPPB0058EA
TAPPB0060EA
TAPPB0061EA
WAVELENGTH (nm)
CATHODE RADIANT SENSITIVITY (mA/W)
QUANTUM EFFICIENCY (%)
100 200 300 400 500 600 700 800 900 1000
10
2
CATHODE
RADIANT
SENSITIVITY
QUANTUM EFFICIENCY
10
1
10
0
10
1
10
2
NOTE a : If the phosphor screen luminance is Lo (cd/m
2
) and the photo-
cathode illuminance is Ei (lx), the image intensification (gain) G is
given by
NOTE: Corresponds to the scale of the gain control knob.
5
Figure 7: Typical Radiant Emittance Gain and EBI (Equivalent Background Input)
C7244
C7245
NOTE:
Radiant emittance gain is calculated taking the luminous energy of a P-43
phosphor screen as 1 lm/m
2
=1.7
~
10
-3
W/m
2
(1 cd/m
2
=5.3
~
10
-3
W/m
2
).
EBI (radiant) is specified as the input energy required to produce a
luminous emittance on the phosphor screen which is equal to that obtained
when the input light is zero. This indicates the lower detection limit of the
image intensifier.
Figure 8: Gate Characteristics
NOTE:
After gate signal input, the rise time required for the entire photocathode to operate
(time required for the phosphor screen luminance to reach from 10% to 90% of the
steady level) is 2ns. The fall time required for the photocathode to turn off (time
required for the phosphor screen luminance to change from 90% to 10% of the
steady level) is 3ns.
10
5
10
4
10
3
10
2
10
-11
10
-12
10
-13
10
-14
200
300
400
500
600
700
800
900
1000
WAVELENGTH (nm)
RADIANT EMITTANCE GAIN (W/m
2
/W/m
2
)
EBI (W/cm
2
)
EBI Max.
AT GAIN MAX.
GAIN Typ.
10
7
10
6
10
5
10
4
10
-11
10
-12
10
-13
10
-14
200
300
400
500
600
700
800
900
1000
EBI Max.
AT GAIN MAX.
WAVELENGTH (nm)
RADIANT EMITTANCE GAIN (W/m
2
/W/m
2
)
EBI (W/cm
2
)
GAIN Typ.
120
100
80
60
40
20
0
TIME (5ns/Div.)
RELATIVE PHOSPHOR SCREEN BRIGHTNESS (%)
2ns
(RISE)
3ns
(FALL)
3ns to 100ms
(GATE TIME)
TAPPB0051EA
TAPPB0052EA
TAPPB0053EA
HIGH-SPEED GATED IMAGE INTENSIFIER UNITS C7244, C7245
6
Figure 9: Typical Shutter Ratio (Extinction Ratio)
NOTE:
The above graph shows relative changes in phosphor screen luminance
when the photocathode DC voltage is changed with respect to the MCP-IN
potential. The dynamic shutter ratio during gate operation depends on the
repetition frequency and incident light intensity. It also greatly depends on
the incident light wavelength.
Figure 10: Typical MTF (Modulation Transfer Function)
Figure 11: Typical Phosphor Screen Emission Distribution
Figure 12: Typical Phosphor Screen Decay (P-43)
10
6
10
2
10
4
10
-2
10
0
10
-6
10
-4
200
100
0
+100
PHOTOCATHODE TO MCP-IN VOLTAGE (V)
RELATIVE PHOSPHOR SCREEN BRIGHTNESS
1.5
10
12
: C7245
1.6
10
10
: C7244
0
20
40
60
80
10
30
50
70
90
100
0
5
10
15
20
25
30
35
40
SPATIAL RESOLUTION (lp/mm)
MTF (%)
C7244
C7245
0.01
10
100
10
-6
10
-5
10
-4
10
-3
10
-2
DECAY TIME (s)
RELATIVE INTENSITY (%)
INCIDENT LIGHT
PLUSE WIDTH
100ns
1ms
10
s
TAPPB0054EA
TAPPB0055EA
TAPPB0050EB
100
80
60
40
20
0
450
400
550
650
500
700
RELATIVE INTENSITY (%)
WAVELENGTH (nm)
600
P-43
TII B0062EB
7
Phosphor Screen Luminous Emittance During Gating
Figure 13: Typical Incident Light (Radiant Energy) vs.
Output (Luminance Gain) Characteristics
Figure 14: Attenuation Constant
Figure 14 shows how the average gain G
G
during the gate
operation varies with the gate time and repetitive frequency.
You can estimate the average gain G
G
from this graph and the
gain G
D
in normal operation. For example, if the gate time is
100ns and the repetitive frequency is 1Hz, then the attenuation
constant is
=10
-7
. The G
G
is the product of the G
D
multiplied
by
.
G
G
=
G
D
Calculation example (C7244, C7245)
When measuring 500nm monochromatic light of 0.01W/m
2
, the
luminance on the output phosphor screen is 1.2
~
10
6
cd/m
2
. If
gating is executed here at an output gate time of 100ns and a
repetition frequency of 1Hz, then
=10
-7
from Figure 14, so
the phosphor screen luminance is 1.2
~
10
6
~
10
-7
=0.12cd/m
2
.
At this light level, it is understood from Figure 15 that imaging
with a CCD camera using a relay lens is difficult.
Figure 15: Various Cameras and Their Imaging Luminance on Phosphor Screen
10
9
10
8
10
7
10
6
200
300
400
500
600
700
800
900
1000
WAVELENGTH (nm)
GAIN (cd/m
2
/W/m
2
)
TYPICAL
MINIMUM
100Hz
10Hz
1Hz
1kHz
30kHz
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
GATE TIME (s)
ATTENUATION CONSTANT
SIT CAMERA (C1000-12)
CCD CAMERA WITH FIBER WINDOW (C6588)
2:1 RELAY LENS A2098+CCD CAMERA C5405
1:1 RELAY LENS A4539+CCD CAMERA C5405
10
-3
10
-2
10
-1
10
0
10
1
10
2
PHOSPHOR SCREEN
BRIGHTNESS (P-43)
MAXIMUM BRIGHTNESS
(10 cd/m
2
)
OVER-LIGHT PROTECTION
LEVEL (20cd/m
2
)
(cd/m
2
)
TAPPB0062EA
TAPPB0059EA
TAPPC0069EA
Accessories
E
Relay lens A2098
This is a relay lens with a reduction ratio of 1/2 and used to
read out an image with a CCD camera. An image produced
on the output phosphor screen of the image intensifier is
focused onto the CCD input surface. Since the reduction ratio
is 1/2, it is necessary to use an objective lens with an
effective image area larger than 1 inch.
F
Image booster unit C4412
When reading out a low-light-level image with a high-speed
camera, the light intensity of the image may be insufficient.
This image booster can be connected to the image intensifier
head by fiber coupling, in order to enhance the light intensity
of the output image up to 30 times.
G
CCD camera C5405
A monochrome CCD camera with a 1/2-inch image format.
This CCD camera features no burn-in, a compact and
lightweight body, and external synchronization.
H
AC adapter A3472-50,-51
An adapter unit that converts AC power into a DC power for
driving a CCD camera (C6588 with fiber optic window or
C5405).
I
Relay lens A4539
A relay lens with a magnification of 1. Use this relay lens
depending on the CCD camera image angle. This relay lens
can be connected to the A2095 C-mount converter.
J
Camera Cable A5963 Series
The cable which provides the power to the CCD camera and
outputs the video signal. It has 12 pin connector and available
in 4 kinds of length from 2m to 25m.
@
C-mount converter A2095 series
Converts the mount of a commercial interchangeable lens for
35mm SLR cameras into a C-mount. Mounts for other
camera manufacturers are also available.
A
UV lens A4869
Commercially available objective lenses cannot transmit light
at wavelengths shorter than about 350nm. The A4869
transmits UV light down to 200nm. To obtain an image only in
the UV range, Hamamatsu also provides UV filters that cut
the visible light.
B
C-mount adapter A4212
An adapter for installing a C-mount objective lens to the
image intensifier head of the C7244 or C7245. This C-mount
adapter is also designed to fit on the output fiber optic side,
so it can be used as an adapter for installing a C-mount relay
lens.
C
CCD camera with fiber optic window C6588
A CCD camera with a fiber optic window having a 1-inch
effective image format (12.8mm
~
9.6mm). This CCD
camera easily connects to the image intensifier head.
D
Relay lens adapter A4211,-01
An adapter for installing the A2098 relay lens (1/2
~
) or
A4539 (1
~
) to the image intensifier head.
Options for C7244 and C7245 (sold separately)
1 INCH OBJECTIVE LENS
(Use commercial lens.)
REPLACEABLE 35 mm
CAMERA LENS
(Use commercial lens.)
1
C-MOUNT
CONVERTER
A2095 SERIES
2
UV LENS
A4869
8
CCD CAMERA
C5405
1"-32UNC C-MOUNT
82
80
102
113.5
80
9
CAMERA CABLE
A5963 SERIES
A
CAMERA CABLE
A5963 SERIES
A
AC ADAPTER
A3472-50,-51
9
AC ADAPTER
A3472-50,-51
4
CCD CAMERA WITH FIBER WINDOW C6588
1/4"-20UNC TAP
AC INPUT
AC INPUT
DELAY/WIDTH
TRIGGER
C-MOUNT ADAPTER
A4212
3
PHOSPHOR SCREEN
PHOTOCATHODE
HIGH-SPEED
GATING POWER SUPPLY
HIGH-SPEED GATED IMAGE
INTENSIFIER HEAD
VIDEO SIGNAL OUT
VIDEO SIGNAL OUT
RELAY LENS ADAPTER A4211
5
RELAY LENS
ADAPTER
A4211-01
5
RELAY LENS A2098 (1/2 MAGNIFICATION)
6
RELAY LENS
A4539
(1 MAGNIFICATION)
0
HIGH-SPEED CAMERA
IMAGE BOOSTER UNIT C4412
7
C-MOUNT
CONVERTER
A2095 SERIES
1
TAPPC0070EA
HIGH-SPEED GATED IMAGE INTENSIFIER UNITS C7244, C7245
8
9
HIGH-SPEED GATED IMAGE INTENSIFIER UNITS C7244, C7245
10
Glossary of Terms Used in This Catalog
Luminous emittance
This is a luminous flux density emitted from a phosphor screen and
usually expressed in radlux (rlx) or lumens per square meter (lm/m
2
).
Luminous emittance of a perfect diffusion surface whose luminance
is even in any direction is given by:
~
l
uminance (cd/m
2
). One
radlux equals 0.318 nt.
Magnification
The image size reproduced on the phosphor screen divided by the
input image focused on the photocathode surface. The average
magnification value around the tube axis is used to specify a typical
magnification.
MTF (modulation transfer function)
In measuring of spatial resolution by using a black/white stripe test
pattern, as the stripe pattern density increases, the black/white
contrast produced on the output phosphor screen becomes lower
and finally reaches a limit below which the stripe pattern is indis-
cernible. The relation between this contrast percentage and the
number of stripes (line pairs) per millimeter is referred to as the
MTF. The MTF is usually specified at a certain number of line pairs.
Photocathode
A photoelectric surface which emits electrons in response to light
input. Different spectral response characteristics can be selected by
an appropriate combination of photocathode material and window
material.
Photocathode illuminance (E) and object illumi-
nance (Eo)
When a complete diffusion object with a reflectivity of R is viewed
by using an objective lens with an F-number of F
N
and transmit-
tance of T
L
, the photocathode illuminance E through the objective
lens is given as follows:
Distortion
The geometric distortion of an image intensifier arises from the
difference between the magnification of the image at the center and
at the periphery. This distor tion is defined as follows:
where M
0
is the magnification in a 1mm diameter area on the tube
axis and M
80
is the magnification of a point at 80% of the effective
photocathode radius from the center. Since the C7244 and C7245
use a proximity-focused image intensifier, they have very low
distortion.
where Eo is the object illuminance.
When F
N
=2.8, T
L
=0.6 and R=0.5, the ratio of the photocathode
illuminance to the object illuminance becomes
EBI (equivalent background input)
This is a parameter to evaluate the background noise of an image
intensifier and is specified as the input illuminance or energy
required to produce a luminous emittance on the phosphor screen
equal to that obtained when the input light is zero. This indicates the
lower limit of detectable illuminance of an image intensifier.
Fiber optic plate
A plate made up of a great number of glass fibers arranged parallel
to one another in a coherent bundle, allowing efficient transmission
of an optical image.
Gain
Image intensifier gain is represented in luminous emittance gain in
the visible light range where light intensity is dealt with the sensitiv-
ity of human eyes. In invisible range or at monochromatic wave-
lengths where light intensity should be handled as electromagnetic
radiation energy, image intensifier gain is expressed in terms of
radiant emittance gain.
Luminous emittance gain: The ratio of the phosphor screen
luminous emittance (lumens per square meter; lm/m
2
) to the
illuminance incident on the photocathode (lux).
R
ad
iant emittance gain: This is the ratio of the photon density
(W/m
2
) emitted from the phosphor screen to the photon density
(W/m
2
) incident on the photocathode. In this catalog, the radiant
emittance gain is calculated from the input photon density at the
peak response wavelength of the photocathode and the output
photon density at the peak emission wavelength (545nm) from the
phosphor screen P-43.
Illuminance
This is a luminous flux incident per unit area on a photocathode and
usually expressed in lumens per square meter (lm/m
2
). One lumen
per square meter equals one lux.
Luminance
This is the degree of brightness of per unit area on a phosphor
screen and usually expressed in candelas per square meter (cd/m
2
)
or nits (nt).
(Pincushion distortion)
Photocathode sensitivity
Luminous sensitivity: Photoelectric current produced from the
photocathode when a luminous light flux from a tungsten lamp
(2856K) enters the image intensifier. This is expressed in microam-
peres per lumen (
A/lm). Originally, this was a measure for
evaluating visible light sensors.
Radiant sensitivity: Photoelectric current produced from the
photocathode when monochromatic light enters the image
intensifier. This is expressed in microamperes per watt (
A/W) at
a given wavelength.
Phosphor screen
A screen composed of chemical substances which emit light when
excited by electrons in a vacuum.
Spectral response
Photocathode sensitivity varies with the input light wavelength. The
relation between the photocathode sensitivity and wavelength is
called the spectral response characteristic.
DIAMETER
TAPPC0040EA
EoRT
L
E =
(lux)
4F
N
2
E 1
=
Eo 100
M
80
-
M
0
Distortion =
~ 100%
M
0
11
Structure and Operating Principle of Image Intensifiers
Construction
Figure 16 shows a typical structure of a proximity-focused image
intensifier. In a vacuum ceramic tube, a photocathode that converts
light into photoelectrons, a microchannel plate (MCP) that multi-
plies electrons while retaining two-dimensional information, and a
phosphor screen that reconverts electrons into light are assembled
in close proximity. The periphery of the ceramic tube is potted with
silicone resin to ensure reliability versus the exterior environment.
Figure 16: Structure of proximity-focused image
intensifier
MCP (microchannel plate)
An MCP is a secondary electron multiplier consisting of millions of
glass capillaries (channels) with 10
m diameter, fused and sliced
into the form of a thin disk which is typically 18mm in outside
diameter and 0.48mm in thickness. As shown in Figure 18, when
an electron enters and hits the channel wall, secondary electrons
are produced. These electrons are then drawn by the potential
gradient and impinge on the channel wall many times while
producing additional secondary electrons. As a result, a large
number of electrons are output from the other end of the channel.
This output is more than several thousand times the number of the
input electrons. A typical MCP is comprised of as many as 1.5
millions of channels, each of which corresponds to a pixel and
serves as an independent multiplier.
Figure 17: Schematic representation of MCP
Figure 18: Operating principle of MCP
Operation of image intensifier
When an optical image is focused on the photocathode of an
image intensifier via a lens, the photocathode emits electrons
(electron image) according to the intensity level of the input image.
The electron image is drawn by the parallel electric field to the
input side of the MCP. While the electron image is passing through
each channel of the MCP, electrons are multiplied up to several
thousand times by each single MCP. The multiplied electron image
then strikes the phosphor screen where an optical image is
reproduced. Through this process, the incident light intensity can
be enhanced about a million times.
Spatial resolution of the image intensifier varies according to the
amount of light incident on the photocathode as shown in Figure
19. When the photocathode illuminance is below 10
-4
lux, increas-
ing the image intensifier gain over a certain level does not improve
the spatial resolution, even though the light spots on the phosphor
screen may become brighter. For improving spatial resolution, it is
essential to increase the incident light level on the photocathode
by using brighter input optics. Another effective technique is taking
the output image with another imaging device and accumulating it
in a frame memor y for reproduction of the accumulated image.
Photon counting imaging is often used at light levels of less than
10
-5
lux in order to obtain an image.
Figure 19: Spatial resolution characteristics
CERAMIC TUBE
OUTPUT WINDOW
(FIBER PLATE)
SILICON RESIN
PHOSPHOR SCREEN
PHOSPHOR SCREEN
INPUT WINDOW
(QUARTZ)
MCP
40
20
10
8
6
4
2
1
RESOLUTION (lp/mm)
10
-6
10
-5
5
10
-4
5
10
-3
5
10
-2
5
PHOTOCATHODE ILLUMINATION (
lx
)
SCENE CONTRAST: 20%
SCENE CONTRAST: 100%
TII C0037EA
TAPPB0039EA
CHANNEL
CHANNEL WAL
S
ELECTRON
OUTPUT S
INPUT SIDE
ELECTRODE
CHANNEL WALL
STRIP CURRENT
ELECTRON
OUTPUT
ELECTRONS
VD
OUTPUT SIDE ELECTRODE
INPUT SIDE
ELECTRODE
TMCPC0002EC
TMCPC0002EC
Figure 20: Dimensional Outlines (Unit: mm)
PRECAUTION DURING USE
Specifications and characteristics are subject to change without notice.
HIGH-SPEED GATED
IMAGE INTENSIFIER HEAD
Always use the high-speed image intensifier head in combination with the controller, because the head
incorporates a circuit which operates with the controller.
Take sufficient care when handling the image intensifier head cable since it contains a high-voltage line
and signal wires.
To minimize deterioration of the image intensifier, do not increase the phosphor screen brightness any
more than is necessary.
HIGH-SPEED GATED IMAGE INTENSIFIER UNITS C7244, C7245
100
10
TAPPA0035EA
200
GAIN ADJUSTMENT DIAL
DISPLAY
DISPLAY SWITCH
TRIGGER INPUT (BNC)
DESTANCE FROM
HEAD SURFACE
TO PHOTOCATHODE
FIXING M3 TAP
(4 PIECES EACH ON
FRONT AND REAR)
TRIGGER POLARITY
TRIGGER LEVEL
FIBER OPTIC PLATE
(EFFECTIVE AREA: 17.5)
DELAY/WIDTH
TRIGGER
255
2000
80
P.C.D. 67
22
PHOTOCATHOCE
(EFFECTIVE AREA: 17.5)
18
9
29
1
RESET SWITCH
PROTECTION DISPLAY LED
MODE SELECTION
SWITCH
POWER
SWITCH
HAMAMATSU PHOTONICS K.K., Electron Tube Center
314-5, Shimokanzo, Toyooka-village, Iwata-gun, Shizuoka-ken, 438-0193, Japan, Telephone: (81)539/62-5248, Fax: (81)539/62-2205, Telex: 4225-186HAMAHQ
U.S.A.: Hamamatsu Corporation: 360 Foothill Road, Bridgewater, N.J. 08807-0910, U.S.A., Telephone: (1)908-231-0960, Fax: (1)908-231-12 18
Germany: Hamamatsu Photonics Deutschland GmbH: Arzbergerstr. 10, D-82211 Herrsching am Ammersee, Germany, Telephone: (49)8152-375-0, Fax: (49)8152-2658
France: Hamamatsu Photonics France S.A.R.L.: 8, Rue du Saule Trapu, Parc du Moulin de Massy, 91882 Massy Cedex, France, Telephone: (33)1 69 53 71 00, Fax: (33)1 69 53 71 10
United Kingdom: Hamamatsu Photonics UK Limited: Lough Point, 2 Gladbeck Way, Windmill Hill, Enfield, Middlesex EN2 7JA, United Kingdom, Telephone: (44)181-367-3560, Fax: (44)181-367-6384
North Europe: Hamamatsu Photonics Norden AB: FSrsgatan 7, S-164-40 Kista, Sweden, Telephone: (46)8-703-29-50, Fax: (46)8-750-58-95
Italy: Hamamatsu Photonics Italia S.R.L.: Via Della Moia, 1/E 20020 Arese, (Milano), Italy, Telephone: (39)2-935 81 733, Fax: (39)2-935 81 741
TAPP1027E01
DEC. 1997. CR
Printed in Japan (1500)
TAPPA0035EA
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