Particle imaging velocimetry (PIV) is a powerful method for the analysis of flow, turbulence, microfluids, spray atomisation and combustion processes. It allows the characterization of the speed of gas or liquid flow, its stream characteristics etc.
In an typical set-up, a special camera observes the gas or liquid stream. Within a short time interval two images are acquired. Each image is illuminated by a relatively short laser pulse. The two consecutive images are then analyzed using an image analysis system in order to determine the flow speed and flow direction of the particles in the stream.
Application set-up (schematic)
Hamamatsu offers a number of cameras dedicated for PIV imaging tasks. (Note: Hamamatsu does not offer image analysis systems for PIV. For simple PIV image acquisition, our software packages HoKaWo or HiPic can be used). These cameras operate in a special "PIV" mode, which allows the recording of two images within a short time interval in order of Nanoseconds.
In PIV mode the camera is waiting for an external trigger pulse which indicates the start of an acquisition sequence. Shortly after the trigger pulse has been received the camera will start the first exposure. The exposure time is determined by a command which had been sent to the camera earlier. During the exposure, the first light pulse has to be shot by the experimental set-up. Typically 40 - 60 Nanoseconds after the end of the exposure the cameras will start the second exposure; and now the second light pulse should be shot. After completion of the exposure, the two images will be read via the digital interface to the PC. This closes an acquisition sequence. Now the camera is again waiting for an external trigger pulse to start the next sequence.
Typical timing diagram of PIV operation mode (example of C9300-024):
The following cameras are available with a PIV operation mode:
| Camera |
Resolution (pixel) |
Cooling |
Frame rate (frames per second) at full resolution* |
Time interval between first and second PIV image (min) |
Data Interface |
Special feature |
| C4742-95-12ER + PIV option |
1344 x 1024 |
Peltier cooling (-25°C) |
8.3 |
< 200 ns |
RS422 |
Low noise |
| C8484-05CP |
1344 x 1024 |
Passive air cooled |
12.2 |
< 200 ns |
CameraLink |
Cost effective |
| C9300-201 |
640 x 480 |
Passive air cooled |
150 |
< 100 ns |
CameraLink |
High frame rate |
| C9300-221 |
640 x 480 |
Peltier cooling (+10°C) |
150 |
< 100 ns |
CameraLink |
High frame rate, low noise |
| C9300-024 |
2048 x 2048 |
Passive air cooled |
11.5 |
< 200 ns |
CameraLink |
High resolution |
| C9300-124 |
4000 x 2672 |
Passive air cooled |
4.5 |
< 200 ns |
CameraLink |
Very high resolution |
*higher frame rates are achieved using binning and/or subarray readout modes
