FEATURES
•
Temporal resolution of within 2 ps
A temporal resolution of 2 ps is achieved for both synchroscan
and single shot.
OPERATING PRINCIPLE
The light pulse to be measured is projected onto the slit and is
focused by the lens into an optical image on the photocathode
of the streak tube. Changing the temporal and spatial offset
slightly each time, four light pulses, each with a different light
itensity, are introduced through the slit and conducted to the
photocathode.
Here, the photons are converted into a number of electrons
proportional to the intensity of the incident light. The four light
pulses are converted sequentially to electrons which are then
accelerated and conducted towards the photocathode.
As the group of electrons created from the four light pulses
passes between a pair of sweep electrodes, a high voltage is
applied (see above), resulting in a high-speed sweep (the elec-
trons are swept in the direction from top to bottom). The elec-
trons are deflected at different times, and at slightly different
angles in the perpendicular direction, and are then conducted
to the MCP (micro-channel plate).
As the electrons pass the MCP, they are multiplied several
thousands of times and are then bombarded against the phos-
phorscreen, where they are converted back into light.
The fluorescence image corresponding to the first incident
light pulse is positioned at the top of the phosphor screen, follo-
wedby the others, with images proceeding in descending or-
der; inother words, the axis in the perpendicular direction on
the phosphor screen serves as the temporal axis. The bright-
nesses ofthe various fluorescence images are proportional to
theintensities of the corresponding incident light pulses. The
positions in the horizontal direction on the phosphor screen
correspond to the positions of the incident light in the horizon-
tal direction.
•
Several plug-in module, operating mode.
•
Accommodates a diverse range of experimental setups
from single light emitting phenomena to high-speed
repeated phenomena in the GHz.
•
Can be used in X-ray to near infrared fields
By selecting the appropriate streak tube (light sensor), the
C5680 can be used in a wide range of measurement appli-
cations, from X-rays to near infrared light.
•
Simultaneous measurement of light intensity on
temporal and spatial (wavelength) axes
Spectrograph can be placed in front of the streak camera, to
convert the spatial axis to a wavelength axis. This enables
changes in the light intensity to be measured over various
wavelength (time-resolved spectroscopy).
•
Ultra-high sensitivity (detection of single photons)
The streak tube converts light into electrons which are then
multiplied by an electron multiplier. This enables detection of
extremely faint light (at the single-photon level).
(See photon counting integration principle)
THE PRINCIPLE OF PHOTON COUNTING INTEGRATION
Photoelectrons given off from the photocathode of the streak
tube are multiplied at a high integration rate by the MCP, and
one photoelectron is counted as one intensity point on the
phosphor screen. A threshold value is then used with this pho-
toelectron image to clearly separate out noise.
Separation of Photoelectron
Image and Noise
Photon Counting Integration
•
IEEE-488 (GP-IB) control
Computer control enables remote control and advanced
measurements to be performed out using very simple op-
eration.
•
Diverse selection of peripheral equipment
A full lineup of peripheral devices is available, including
spectroscopes, optical trigger heads, and expansion units.
A/D
conversion
value
Photoelectron image
Threshold
value
The operating principle of the streak camera
Signal output from CCD camera
Noise
Time
(wavelength)
0ps 200ps 400ps 600ps 800ps 1ns 1.2ns 1.4ns 1.6ns 1.8ns
Trigger signal
Sweep circuit
Sweep electrode
(where electrons
are swept in the
direction from top
to bottom)
Light source: PLP (λ = 800 nm)
Integration time: 1 min.
Streak image
on phosphor screen
Optical
intensity
Lens
Time
Incident light
Space
Slit
Photocathode
(light
→
electrons)
Accelerating electrode
(where electrons
are accelerated)
Phosphor screen
(electrons
→
light)
Time
Space
Positions in the photoelectron image which are above the
threshold value are detected and are integrated in the memory,
enabling noise to be eliminated completely. This makes it possi-
ble to achieve data measurements with a high dynamic range
and high S/N.
MCP
(which multiplies
electrons)
The intensity of the incident light
can be read from the brightness
of the phosphor screen, and the
time and space from the position
of the phosphor screen.
2
HAMAMATSU [ HAMAMATSU CORPORATION ]
