Sensing the world
·
Leading the change
6
D = 3mm + 0.010rad × U(mm)
0
10
5
15
25
20
100
200
300
400
Be
am
Siz
e(m
m)
Distance(m)
Laser beam diameter at different detection distances
The relationship between the spot diameter D and the detection distance U is:
Figure 2-4
As shown in Figure 2-6, when the object to be measured at a specific distance is larger than the spot size of the
laser, the object to be tested can be stably detected. When the object under test is smaller than the laser spot size
at this distance, the smaller the area of the object under test that occupies the area of the laser spot, the easier the
object will be missed. Whether it is missed or not depends on the ratio of the measured object to the spot size,
the tilt angle of the object itself, the reflectivity of the object itself, etc. We will give the reflectivity requirements
for stable detection of objects in Figure 2-8. You can calculate the equivalent reflection according to Figure 2-6
and Equation 2-1 based on the object's inclination, the area of the object and the actual reflectivity of the object
The rate is compared with the curve shown in Figure 2-8.
Object projection area
Spot diameter
Laser exit direction
Object normal
Figure 2-5 Calculation of equivalent reflectance
Equivalent reflectance calculation: where η is the equivalent reflectivity of the object, is the
projection of the object in the radar exit direction, is the spot size, θ is the angle between the
surface normal of the object and the radar exit direction, and η is the reflection of the object itself
rate,
e
o
beam
o
S
S
