Falcon 4M Camera Manual
DALSA 03-032-20044-01
61
4.2 Lens Mounts
Configuration
Flange Back Focal Length (sensor die to adapter)
M42
6.56 ±0.25 mm
F-Mount
46.50 ±0.25 mm
C-Mount*
17.52 ±0.25 mm
*Note that the use of a C-Mount lens requires a C-mount adapter, and may cause
vignetting due to the size of the image sensor.
4.3 Optical Interface
Illumination
The amount and wavelengths of light required to capture useful images depend on the
particular application. Factors include the nature, speed, and spectral characteristics of
objects being imaged, exposure times, light source characteristics, environmental and
acquisition system specifics, and more. DALSA’s Web site,
http://mv.dalsa.com/
,
provides an introduction to this potentially complicated issue. See “Radiometry and
Photo Responsivity” and "Sensitivities in Photometric Units" in the CCD Technology
Primer found under the Application Support link.
It is often more important to consider exposure than illumination. The total amount of
energy (which is related to the total number of photons reaching the sensor) is more
important than the rate at which it arrives. For example, 5
μ
J/cm
2
can be achieved by
exposing 5mW/cm
2
for 1 ms just the same as exposing an intensity of 5W/cm
2
for 1
μ
s.
Light Sources
Keep these guidelines in mind when setting up your light source:
•
LED light sources are relatively inexpensive, provide a uniform field, and longer life
span compared to other light sources. However, they also require a camera with
excellent sensitivity.
•
Halogen light sources generally provide very little blue relative to IR.
•
Fiber-optic light distribution systems generally transmit very little blue relative to IR.
•
Some light sources age; over their life span they produce less light. This aging may
not be uniform—a light source may produce progressively less light in some areas of
the spectrum but not others.
Filters
Digital cameras are extremely responsive to infrared (IR) wavelengths of light. To prevent
infrared from distorting the images you scan, use a “hot mirror” or IR cutoff filter that
transmits visible wavelengths but does not transmit wavelengths over 750 nm. Examples
are the Schneider Optics™ B+W 489, which includes a mounting ring, the CORION™ LS-
