28 1S 
stem 
OWS 
isily 
nply 
nple 
CIR) 
lizes 
s do 
te of 
287 
data 
ly of 
es is 
s do 
    
principally integrate charges at the end of each field. 
— integration time, shutter "open" 
T readout time 
40 ms 
  
Y 
  
camera 01 
camera 02 
camera 03 
camera 04 
camera 05 
camera 06 
camera 07 
camera 08 
camera 09 
camera 10 
camera 11 
camera 12 
camera 13 
camera 14 
camera 15 
camera 16 
Figure 5: Phase shifted synchronization of 16 CCD cameras 
The image data can again be stored on an analog or a digital 
device. An analog storage on videorecorders (one per cam- 
era!) allows for extremely long image sequences of up to 
240 minutes, but the data handling and the digitization of 
images from the videotapes (Maas, 1990) becomes cumber- 
some, so that such a system cannot really be called an on- 
line system any more. If sequence lengths of about 1.5 sec- 
onds are sufficient, image sequences can be digitized 
directly by framegrabbers equipped with 16 MB frame 
storage avoiding losses in image quality due to the analog 
intermediate image storage (Maas, 1992). For such a digital 
cascaded high-speed camera system 16 framegrabbers with 
16 MB of memory each would be necessary. But although 
consisting of 16 cameras, lenses, framegrabbers, a synchro- 
nization device and probably four host computers, such a 
system (Figure 6) will still be significantly cheaper than the 
factory floor systems mentioned above. 
  
  
  
  
  
  
  
  
  
  
  
    
  
  
16 MB RAM boards 
"t eessesssssssssassssssessssssssseccsossocesossso s. 
Figure 6: Cascaded 16 CCD camera system (scheme) 
It offers the advantage of high flexibility and scalibility, 
however at cost of a relatively expensive data handling due 
to the distribution of data over multiple devices. The main 
  
disadvantage, however, is the fact that, if not a very com- 
plex optical system connecting all sensors to one optical 
path is being designed, depending on the task computation- 
ally expensive image transformations may become neces- 
sary. If these problems are considered tolerable for the 
designated task, cascaded CCD cameras can be a very pow- 
erful high-speed system. 
Conclusion 
The use of high-speed solid state sensor systems allows for 
the design of very efficient, flexible measurement systems. 
Although more expensive, systems which come with digital 
data storage offer some important advantages to users who 
are interested in more than just a visual slow motion inter- 
pretation of recorded data. But even in factory floor sys- 
tems which are mainly designed for slow motion playback 
there is a clear tendency towards completely digital sys- 
tems. Most interesting from the point of view of a user 
from machine vision or digital photogrammetry are PC- 
based systems with data rates of up to 32 MHz and RAM 
sequence storage, which can be purchased at a relatively 
moderate price (relatively as compared with other systems, 
not absolutely), or realtime disks, which offer much larger 
storage capacities. The technique in this sector is develop- 
ing quite rapidly, so that very soon systems with higher data 
rates and larger storage capacity will be available. 
References 
1. Dahm, W., Southerland, K., Buch, K., 1990: Four-di- 
mensional laser induced flourescence measurements of 
conserved scalar mixing in turbulent flows. Proceedings 
5th International Symposium on the Application of La- 
ser Techniques in Fluid Mechanics, Lisbon, July 9-12 
2. Godding, R., 1990: A system for the photogrammetric 
evaluation of digitized high-speed images in the auto- 
mobile industry. ISPRS Com. V Symposium Zürich, 3.- 
7. 9. 1990, published in SPIE Proceedings Series Vol. 
1305 
3. Hyzer, W., 1990: Tech Talk - What's new in High 
Speed. Photomethods July 1990 
4. Johnson, H., 1990: High Speed - News from the High 
Speed Photography, Videography and Photonics Work- 
ing Group of SPIE. OE Reports October 1990 
5. Maas, H.-G., 1990: Digital Photogrammetry for Deter- 
mination of Tracer Particle Coordinates in Turbulent 
Flow Research. ISPRS Com. V Symposium Zürich, 3.- 
7. 9. 1990, published in SPIE Proceedings Series Vol. 
1395 
6. Maas, H.-G., 1992: Digitale Photogrammetrie in der 
dreidimensionalen Strömungsmeßtechnik. PhD. Thesis 
No. 9665, ETH Zurich 
7. Miquel, J. C., 1987: High Speed Video Recording. 
Lavoisier Publishing Inc., New York 
Manufacturer brochures of Dalsa, EG&G Reticon, 
Fraunhofer Institute, Kodak, NAC, RCI, Sony 
pe