DOUBLE PULSED HOLOGRAPHIC INTERFEROMETRY ON HUMAN BEINGS
HIN. VIVOY
by M. DE CALUWE and P.M. BOONE**
ABSTRACT. The use of a pulsed ruby laser in recording holographic interferograms of
specific surface displacements of the human body is demonstrated. Technical particularities
of the technique are discussed and attention is paid to the safety requirements of
the measurement method.
SOMMAIRE. On montre l'usage d’un laser à rubis à double impulsion pour l'enregistrement
d'interférogrammes holographiques de déplacement de la surface du corps humain. Les
particularités techniques sont prises en considération; une attention est donnée aux
aspects de sécurité.
ABSTRAKT. Es wird die Benutzung eines Doppelpulsrubin lasers für die Speicherung
holographische Interferogramme von Bestimmten Oberfláchendehnungen des menschlichen
Kürpers demonstriert. Hierbei werden Technische Eigenschaften diskutiert und wird
geachtet auf die Sicherheitsbedingungen dieser Messmethode.
1) INTRODUCTION.
The application of a pulsed laser in holographic interferometry
is certainly not new. Particularly at NPL, remarkable work has
been done since the late sixties by Gates, Hall and Ross
(ref.1,2). From than on, the number of people working in this
field is continuously growing.
Since the exposure time is expressed in nanoseconds, we finally
could get rid of the tedious stability criterion particular to
set-ups with CW-lasers. It 1s obvious that very quickly after
the equipment has been available, holograms could be seen of
living people; the term "holoportrait” being not yet applicable
ta those "shots" !
More than ten years after the first experiments, the pulsed
laser has become a reliable tool, with predictable and reprodu-
cible pulse energies and intervals. However, only few publica-
tions in the biomechanical field can be found. This brought us
to the idea of using our equipment - initially designed for
investigation in applied mechanics - for experiments on human
beings, principally to obtain a general idea of the specific
technical difficulties which characterizes this method when
used in traumatology and orthopedics, and what can be expected
from the pictures.
It must be kept in mind that these experiments were not part
of a true medical investigation.
2) THE EQUIPMENT.
a. General, It is supposed that the principles of ruby lasers
are known so that we can concentrate on specific particulari-
ties of our equipment. This was a JK type 2000 holocamera
(ref.3) which comprises a holographic ruby oscillator, coupled
to two ruby amplifiers, to provide 2J TEMoo output in one or
two pulses (Fig.1), and additional optics for generating the
reference beam.
t Seminar for Mechanics of Machines.
$t Laboratory for Strength of Materials
both at Ghent University, Belgium.
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