Interference No. 103,197
Morrison described the experiment, the researcher's
finger pulse creates a pulsatile motion artifact. In the
absence of noise, i.e., when Dr. Morrison happened to
keep the needles so steady that only his finger pulse was
taken up, he happened to create an acceptable signal.
Specifically, this finger pulse caused variations in the
spacing of the needle tips:101
[I]t is obvious that the pulse he detected was his own
pulse, but the origin was not the arterial blood moving
in an out (= arterial pulse) but a motion artifact, i.e.
a changing distance between two fiber tips creating a
changing pulse length through tissue with all the
components present, tissue, venous blood, capillary
blood, arterial blood while only the arterial blood
should change (optical plethysmography).
This argument has support in the following test conducted by
Falkowski, which he offered in support of the argument,
discussed infra, that a needle spacing of 1 or 2mm of tissue
is too close to provide a detectable modulation signal even
under optimal coupling conditions, i.e., without using optical
fibers.
Although Falkowski does not so state, Morrison appears to102
accept Buschmann's claim that this test was performed on a103
BR 31, ¶ 11.101
Morr.Open.Br. 37.102
B.Br. 75; Buschmann, BR 19, ¶ 27.103
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