User guide

Trimble M3 Total Station User Guide 51
Getting Started in the Field 4
4.1 Setting the measurement mode and preparing the target
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WARNING – The Trimble M3 3” and 5” DR total stations are Class 1 laser instruments. The
laser beam is hazardous to the eyes and the body. Do not sight the instrument on the face
or body of a person. If you suspect an injury caused by exposure to the laser beam, seek
medical advice immediately. If the instrument housing is open and the instrument is
turned on, the laser emits a beam stronger than the Class 1 safety level.
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WARNING – Observe all other warnings and cautions. See Safety and Warnings, page iii.
The Trimble M3 total station has two measurement modes: Prism mode (Prism) and
Direct Reflex mode (
DR). To change the mode at any time from any observation screen,
press and then press
[2]. See also Changing target mode (DR or Prism), page 40.
Tab le 4.4 describes how to set the measurement mode depending on the target you
want to measure.
41.1 Measurement with a prism
As the Trimble M3 total station is extremely sensitive, multiple reflections on the prism
surface can sometimes cause a significant loss in accuracy.
To maintain the accuracy of your measurements:
• Do not use a prism with scratches, a dirty surface, or a chipped center. Trimble
recommends that you use prisms with thin edges as shown below.
• When using a reflector sheet, take measurements longer than 5 meters.
• When using a mini or standard prism, take measurements longer than
10 meters.
Table 4.4 Measurement modes
Target Target settings Indicator on status bar
Prism, reflector sheet Prism (Prism mode)
Other, reflective materials DR (Direct-Reflex mode)
✓
✕
✕
Thin edges
Chipped center
Thick edges