{!{!{2z=2\cdot ∆y'\cdot K\cdot \frac{1}{\beta}(1+\frac{1}{\beta})}!}!}
using the F-number K, the pixel pitch (mm) ∆y’, and the magnification β.
Depth of focus
The depth of focus 2z is calculated from
Depth of focus scheme
Depth of focus 2z
Line scan sensor with pixel pitch ∆y’ focal length f and
F-number K.
The depth of focus is defined as 2z.
Example
Pixel pitch ∆y’ = 0.014 mm
1/magnification 1/β = 10
F-number K = 4
Depth of focus 2z = 2·0.014mm·4·10·(1+10) = 12.3mm
| F-number K | Depth of Focus 2z (mm)* | Relative signal amplitude |
|---|---|---|
| 2 | 6.2 | 16 |
| 2.8 | 8.6 | 8 |
| 4 | 12.3 | 4 |
| 5.6 | 17.2 | 2 |
| 8 | 24.6 | 1 |
| 11 | 33.9 | 1/2 |
| 22 | 67.8 | 1/4 |
| 32 | 98.6 | 1/8 |
| * for ∆y' = 0.014 mm and β = 1/10 | ||
Lens parameters scheme
Imaging Parameters
Schematic depiction of the imaging system and definition of variables used.
f = Lens focal length (mm)
S = Sensor length (mm)
L = Length of Region of Interest (ROI) of object (mm)
a = Object range (mm)
a’ = Image distance: Distance from sensor to HH’ (mm)
β = Magnification
w = Field angle
OO’ = Distance from sensor to measured zone (mm)
s’A = Flange focal length (mm)
∆s’ = Lens extension (mm)
LT = Tube length
A = Working distance (mm)
HH’ = Principal point distance (mm) (can lengthen or shorten OO’)
s’K = Camera flange length consisting of focus adapter series FA22 and extension rings series ZR (mm)
LO = Lens length (mm)