Spectra AL28M-1 Laser Level User Manual


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Features
01. Focusing knob
02. Sighting guide
03. Crosshairs’ adjustment screws (under cover)
04. Crosshairs’ focusing ring
05. Eyepiece
06. Horizontal rotation ring and angle index
07. Leveling screws
08. Base plate
09. Circular level adjustment screws
10. Horizontal tangent knob
11. Circular level
12. Mirror for reading circular level
13. Objective
Maintenance and Care
• Aswithallprecisioninstruments,theautolevelshouldbe
transported and stored in its carrying case.
• Whencarryingtheinstrumentmountedtoatripod,besure
to carry it vertically rather than over your shoulder.
• Wheneverpossible,storetheinstrumentinadry,shadyarea.
• Wipetheinstrumentcleanwithacloth.Cleantheobjective
andeyepieceswithspecialcareusingadamptissueorsoft,
clean,lint-freecottoncloth.
• Whenworkinginwetweather,wipeofftheinstrumentand
carrying case in the field and let them dry completely indoors
with the case open.
Safety Information
Included in this manual are Cautions and Notes. Each of
thesewordsrepresentsalevelofdangerorconcern.ACaution
indicates a hazard or unsafe practice that could result in
minorinjuryorpropertydamage.ANoteindicatesimportant
information unrelated to safety.
Establishing an Elevation
1. Set up and level the instrument.
2. Set the grade rod on a known elevation (30.55 m) and take a
grade rod reading (1.72 m).
3.Addthegraderodreadingtotheknownelevationtogetthe
height of instrument or HI (1.72 + 30.55 = 32.27 m).
4. Subtract the elevation of the point you want to establish
(31.02 m) from the HI (32.27) to calculate the difference
between the two points (32.27 – 31.02 =1.25 m).
5. Go to the point you want to establish and adjust the height of
the grade rod until the calculated difference (1.25) is centered
in the crosshairs.
Taking Measurements
Determining the Difference in Elevation
How to Use the Instrument
Setting Up the Instrument
1. Set up the tripod at a height appropriate for your use.
Note: Make sure the tripod is stable and the tripod head is
relatively level.
2.Attachtheinstrumenttothetripod.
3. Level the instrument using the circular level as a reference.
4. Focus the telescope crosshairs by turning the crosshairs’
focusing ring.
Aligning the Instrument
1.Alignthetelescopetothegraderodusingthesightingguides.
2. Turn the focusing knob to bring the grade rod into sharp
focus. Precisely sight the center of the grade rod in the
telescope crosshairs using the horizontal tangent knob.
3. Check for parallax shift.
Note: No parallax exists if the crosshairs and the grade rod
graduations remain in coincidence even when you change
your viewing angle (move your eye up/down and left/right in
front of the eyepiece).
Note:Afterthebubbleinthecircularlevelhasbeencentered,
thecompensatorcorrectsresidualline-of-sightinclinations.
Thecompensatordoesnot,however,eliminateanytilts
resulting from inadequate adjustment of the circular level or
lineofsight.Thesemustbecheckedregularly(seeAdjusting
the Instrument for more information).
Taking a Distance Measurement
Note: The instrument’s stadia lines allow you to determine the
distance between the instrument and the grade rod.
1. Take readings at the upper stadia
line (1.436 m) and the lower stadia
line (1.152 m).
2. Calculate the difference between
the two readings (1.436 – 1.152 =
0.284 m).
3. Multiply the difference by 100
to get the distance between the
instrument and the grade rod
(.284 x 100 = 28.4).
Computation Example
Elevation
Center Line Reading 1.294 m
Distance Measurement
Upper Stadia Line Reading 1.436 m
Lower Stadia Line Reading 1.152 m
Difference 0.284 m
Distance (0.284 x 100) 28. 4 m
– 2 – – 3 – – 4 –
–
5 – – 6 –
– 7 – – 8 –
7
5
4
8
13
12
10
11
9
3
6
2
1
1.Setuptheinstrumenthalfwaybetweentwopoints(AandB).
2.TakeareadingatpointA(a
1
= 1.726 m) and another one at
point B (b
1
=1.259 m).
Note:Aslightdeviationofthelineofsightfromhorizontal
will not cause any measuring error as long as the instrument
is set up approximately half way between the two points.
3. Subtract b
1
from a
1
to get the difference between the points
(d = 0.467 m).
Note:PointBis0.467higherthanpointAbecausethe
difference is a positive number. If point B were lower than
pointA,thenumberwouldbenegative.
1 5
1 4
1 3
1 2
1 1
1 0
AL 24/28/32 - A/M Series
Auto Levels
User Guide
www.trimble.com
•
a
1
b
1
A
B
1.259
1.726
0.467