Setting The Measuring / Focus Distance; Manually Focusable Optics; Spot Size Table; Calculation Of The Spot Size Diameter Outside The Focused Distance - Sensor Therm METIS M3F1 User Manual

METIS M3F1
Mechanical Installation
5.5

Setting the Measuring / Focus Distance

The focal distance is the distance at which the lens has the smallest spot size. In most cases, this dis-
tance is also the required measuring distance.
 With focusable optics, the focus distance can be changed continuously within a predetermined range,
so the smallest possible spot size is always achieved.

Manually Focusable Optics

5.5.1
 Release optics turn counterclockwise
 Move optics in or out until the measured distance is found (see
Measuring Technology or via the optics pull-out in the Spot Size
Tables, section 5.6).
- Pulled optics: short measuring distance
- Inserted optics: long distance measurement
 Lock optics turn clockwise (hand-screwed, without tools).
5.6

Spot Size Table

The following tables show the optical
data of the A1 optics.
The values in the tables are exempla-
ry, intermediate measurement dis-
tances must be determined by inter-
polation. If the measuring distance dif-
fers from the adjusted or specified, a
measurement is also possible, but the
spot size changes (usually it is larger,
see 5.6.1 Calculation of the Spot
Size Diameter outside the Focused
Distance). Measuring distances are
specified from lens front.

Calculation of the Spot Size Diameter outside the Focused Distance

5.6.1
The spot size diameter determines the area on the measurement object from which 90% of the temper-
ature radiation is detected by the pyrometer; therefor the spot size tables specify spot sizes for different
measuring distances (or focused distances).
For calculating intermediate values in front of and behind the focused measuring distance, the following
formula can be used or the spot size calculator integrated in SensorTools (see 7.4):
a Focused distance
M Spot size diameter in the focused measuring
distance
a Measuring distance longer than focused
1
measuring distance
M Resulting spot size on measuring distance a
1
a Measuring distance shorter than focused
2
measuring distance
M Resulting spot size on measuring distance a
2
D Aperture (specifies the spot size directly on
the objective lens, it differs depending on the
optics pull-out. The largest value applies at a fully extended optics, the lowest value is with inserted
optics)
Spot size
Optics
a [mm]
340
400
500
600
800
OQ11-A1
1000
1500
2000
2500
3000
Aperture diameter D: 7-8 mm
1
M M
1
a
1
M = (M+D)-D
1
a
2
1. Release
2. Adjust
5.3
3. Lock
1
2
Optics
pull-out
S [mm]
26
20.7
15.5
11.7
7.7
5.5
2.7
1.3
0.5
0
a
1
a
a
2
M
2
a
2
M = (M-D)+D
2
a
3
Spot size
diameter
M [mm]
0.8
1.3
1.5
1.8
2.3
2.8
4.6
5.8
7.3
7.8
13