HP 5528A

Model 5528A
Strall:! htness and Squareness Considera ti ons
21-2
c. D ete rmine what " Y" s hould be for each "X" alonl:! your measurem eOl path using the
equation above. Thi s wi ll be -
V "o pe
d. Subtract all the va lu es you calc ul ated in st ep " c" fr om the va lu es you actually measur ed
wilh the la ser Meas urement System, lea v in g you wit h "t ru e" Stra ig htness va lu es
Here is an example of ca lc ul ating "slo pe " and then "tf ue" Stril ightncss va lu es for two axes of
measur
eme nt. We use va lues for two axes because we w ill use the "s lop e" values in our
Squareness cil lculations later.
Th e important va ri ab les are -
For A xis 1
m
= slope of the mi salignment axi s
b = interc ept of the misalignment axi s
x
"'" position of the machine along the axi s of travel
V "ope - va lue of the bias du e to mi sa li gnment (slope) of
the
Opti cal straight edge ax is with the a xis of tr avel
Y lrue :z true value of the out-of-straightness of the machine
YU.4$ = r ead ing on the las er display
Our raw data is
YLM S = - 0.], 0.9, 1 .5,2 .5 , 2.9 , 3.6,4.2,5 .1 ,5.9,7.2 (micron s)
X = 0.0,0.1,0.2,0 . 3,0.4,0 .5, 0 .6, 0 .7, 0.8, 0.9 (metre)
Number of points
= 10
Calcula
ti ons for Axi s 1 -
Tot al distan ce trave ll ed : 6X = 0 .9 metre
Slo pe m1 = 6V / 6X = (7.2- ( -0 .3 ))/(0.9-0.0)
= 8 .33 m ic rons/ metre
Int
ercept = bl = -0.3 microns (at X = 0, you want Y , rue = 0)