Conversion When Deadpath Is Included - HP 5501A Operating And Service Manual

4.11 DATA HANDLING TIPS
When writing application programs for a specific Laser Transducer System, the applicable
following paragraphs should be read in addition to reviewing the typical programs in Tables
4-72 and 4-73.
a. Subtraction of preset numbers
b. Conversion to inches or metres
c.
Conversion when deadpath i s included
d. Handshaking routine between a controller and the 10746A Binary Interface
e.
Conversion of destination and displacement information when using the 1076214
Comparator
f.
10762A Comparator/10764B Fast Pulse Converter 1 / 0 format
4.12 Subtraction of Preset Numbers
When using the 10745A HP-IB interface subtract the following counts:
a.
160 counts if in normal mode,
b.
16 counts if in extended resolution.
When using the 10746A Binary Interface, the program i s such that you must subtract 160
counts from the raw number that i s transferred. The decimal point information is contained
in D (bits 31-28). After subtracting the 160 counts, multiply the result by 10(2-D) to obtain a
calibrated result.
4.13 Conversion to Inches or Millimetres
In the case of displacement data (X,Y,Z, etc.), it i s normally necessary to convert the raw data
to compensated millimetres or compensated inches. First the number must have the correct
preset number subtracted (and in the case of a binary number, the decimal information applied)
a s explained in the previous paragraphs. The resulting number must then be multipled by the
compensation factor and the proper conversion factor. The conversion factors are a s follows:
a. Multiply by 6.23023X10-6 to convert to inches.
b. Multiply by 1.58248X10-4 to convert to millimetres.
The compensation number corrects for the velocity-of-light (VOL) factor and possibly material
temperature (if the 5510A Opt 010 i s used to monitor this factor). The material temperature com-
pensation converts the information back to a length at 20°C (68OF).These multiplication numbers
assume there is no deadpath.
4.14 Conversion when Deadpath is Included
Deadpath is defined a s the distance between the interferometer and the cube-corner at the 0
(gage) position (see Figure 4-3). I t i s assumed in the following discussion that you have read
and understand the discussions in Section II that explain deadpath and VOL errors.