HP 5528A

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.