di the calibration certificate was set. With the Optronics P-1700 and the
Joyce-Loebl 3C5 the ealibration parameters had to be computed afterwards
from the digital or analogue recorded measuring values.
n acr Thus for each instrument a eus scale was determined relating to the
zo reference step wedge used . With this set adjustment each sample was,
as a rule, measured two times.
the
But in chapter 3 will be demonstrated that the use of only one reference
= step wedge does not suffice.
: In order to have for the analysis of the results an absolute comparison,
: an apparatus (fig.3) of the PTB in Braunschweig was used for the deter-
mination of the diffuse density of all step wedges according to DIN 4512.
er The repeatability of this instrument is indicated with < +0.5% (Heiland
^ ( and Vieth 196h). This value was also obtained by own measurements.
(9
Ulbricht sphere i :
Ulbrichtsche Kugel Dex :
: Apparatus of the Physikalisch-Tech-
sondensing lens nische Bundesanstalt (PTB) in Braun-
Ondensor schweig, Federal Republic of Ger-
I~ | many, for the determination of the
LO Lamp : FI diffuse density after DIN 4512 and
lamp for the determination of the specular
filters density (after Heiland and Vieth
position A 7 B1 1964). In position A the diaphragm
| Bl is inm contact with the U-sphere,
sample i which illuminates the sample dif-
Probe | fusely. From the luminous flux
transmitted the receiver weights
= only a light bundle which has an
i position B angle of 2950' with the optical
je axis. In position B the sample is
(9 gestes also illuminated under an angle of
1 2050'. This time the receiver
broad-band weights a light bundle with an axis
interference” P oto- angle of 3045! Diaphragms and U-
( Sehen ce Ne / SEY sphere have apertures with a dia-
0.25 Interferenzfilter | meter of 5 mm.
. 2
0.54
er This apparatus is also suitable for the determination of the specular
; density in order to be able to compute from the ratio of specular den-
, sity and diffuse density the Callier coefficient. The Callier coefficient
characterizes the light scattering properties of layers (though he does
#) A Kodak photographic step tablet no.3 (calibrated) served as reference
n
for all these measurements.
