Model
5528A
Straightn
ess
and
Sq
uarcness Considerations
SECTION
21
STRAIGHTNESS
AND
SQUARENESS
CONSIDERATIONS
CONTENTS
INTRODUCTION
CALCULATION OF SLO
PE
CALCULATION OF SQUA
RENE
SS
SQ
UA
R
ENESS
SI
GN
CONVENTIONS
INTRODUCTION
This User's Guide Section provides the
inform
ation you need in
orde
r to c
al
culate a
nd
remove the
slope from your
St
rai
ghtn
ess
m
eas
ur
ements or to
ca
lculate the Squaren
ess
between
two
a
xes.
This
Sect
ion will also help you determine the
sig
n conve
ntion
s on yo
ur
St
raightn
ess
me
asu
reme
nt
s
so
yo
ur
Squaren
ess
calculation is correct,
whether
it
is
done
manuall
yo
r automatically (using the
HP
Dimensional
Metrology
Analysis
Syste
m
).
CALCULATION OF
SLOPE
Th
ere are t
wo
methods used to remove the slope value from your data. The first me
thod
is
ca
lled
"
End
Point Fit", and the second is
ca
lled " L
east
Squ
ares
Fit".
End
Point
Fit
Method
To remove slope from your measurement data, using the "
End
Point
Fit
"
method,
you should -
a.
Determine the slope of your data by subtracting
th
e first reading from the l
ast,
and then
dividing by the len
gt
h
of
tr
avel
of
the
Op
ti
cs
.
m (slope) =
l
ast
meas
ur
ement
- first measurement
len
gt
h
of
travel
of
Optic;
b.
Identify the equation
of
the line
of
your slope -
Ysl
o
pe
=
mX
+
b,
where -
Y
wil
l be a calculated
va
lu
e,
X
is
the distance travelled along the measurement path, and
b
is
the fir
st
St
raightne
ss
readin
g.