HP 5528A User Manual

OCT 87
Model 5528A
Straightness and Squareness
Considerations
0 = larctangent (m)l x 3600 (arcseconds)
Be sure your slope value is dimensionless, i.e ., metre / metre or inch/ inch.
This means
dividing the previously-calculated slope values by one million ( 10 6). Using the
values in
our examples, you'll get -
Ca lc ul ation
Term Axi s 1 Va lu e A xi s 2 Value
Method
End-point
m
8.3 x 10-
6
- 18.44 x 10-6
Fit
0
1.7
-3.6
lea st -s quare m
7.65 x 10- 6
-17.42 x 10-6
Fit
0 1.6
- 3.6
2. Determine the sig n of each angle of mi sa l ignment by following the procedures on the
following pages.
This
is very important si n ce adding two angl es will certainly produce a mu ch different
Squareness value than subtracting the same angles.
3. Calculate the total an gle between the two axes by the following formu la (refer to Figure 21-1) -
Total angle = 324000 + 02 - 01 + Optical Square Error
The value
"324000" is the number of arcseconds in a right angle (90 x 3600).
"Optical Square Error" is the number of ar cseco nd s of error in the Optical Square; i.e ., how
far it is from being exactly 90 degrees (324000 arcseconds) square. This va lue is found
printed on the surface of the Optical Square.
Always add
02 and always subtract 01 , regardl ess of their sign conventions. ( See the example
below
.)
4. Calculate Squareness -
Squareness
= 02 - 01 + Optical Square Error
If the Optical Square's error = 0.0, then the Sq uarene ss (using our previous calculations)
i s:
Calculat io n M et hod Sq uaren ess
End-point Fit - 5.5 arcseconds
lea st-squares fit -5.2 arcseconds
21-7

HP 5528A Specifications

General

Brand	HP
Model	5528A
Category	Measuring Instruments
Language	English