Manual Chapter 5

6-27

The following scenario will more clearly illustrate how the Dual Pass

method operates.

1. ···When the analyzer initializes the laser heads, all data is cleared and

they enter the “Dual Pass” mode of operation.

2. ··The laser heads then begin detecting the presence of the other laser

head’s laser beam on its PSD. If a laser beam is not on a PSD, the

laser head's LED will be ﬂashed solid yellow.

3. ··When the other laser head’s laser beam is detected on its PSD, the

laser beam is tracked as it crosses the PSD. As soon as the laser beam

is detected on the PSD, the laser head's LED will be or continue to

be (depending on the state it originally started from) ﬂashed solid

yellow.

4. ··When a laser beam enters the “valid data” window around its PSD’s

vertical centerline, data is acquired. As valid data is acquired, the

laser head will ﬂash its LED green once.

5. ··Data continues to be acquired while a laser beam is within the “valid

data” window. The position data that is closest to the vertical

centerline (i.e. horizontal position closes to zero) is the value that is

retained along with its angular position. As each data sample is taken

the LED on the Laser Head will ﬂash green to indicate that a valid

data point has been acquired.

6. ··If a laser beam passes across the PSD so quickly that a data point is

not acquired within the “valid data” window, no data will be

acquired.

7. ···When a laser beam leaves the PSD completely, the acquired data

point is committed and stored.

8. ··The laser heads again begin detecting the presence of the other laser

head’s laser beam on its PSD and their LED's resumes to be ﬂashed

solid yellow.