National Instruments NI Vision 17 Series, Руководство пользователя

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5-2
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Chapter 5 Image Sensor
Figure 5-1 illustrates horizontal field of view and working distance.
Figure 5-1.
Parameters of an Imaging System
For example, if the working distance of your imaging setup is 100 mm, and the focal length of
the lens is 8 mm, then the field of view in the horizontal direction of a NI 17xx Smart Camera
using the VGA sensor is
(5-2)
Similarly, the field of view in the vertical direction is
(5-3)
Based on the result of Equations 5-2 or 5-3, you can see that you might need to adjust the various
parameters in the FOV equation until you achieve the right combination of components that
match your inspection needs. This might include increasing your working distance, choosing a
lens with a shorter focal length, or changing to a high resolution camera.
Image Sensor Spectral Response
The spectral response curve describes the relative sensitivity of the sensor to different
wavelengths of light. The peak responsiveness of the VGA and SXGA sensors is to light with a
wavelength of approximately 500 nm. If you are imaging a dim scene, this information can be
useful when selecting a light source to use in your application as the camera is most sensitive at
1 Horizontal Imaging Width
2 Working Distance
3 Horizontal Field of View
2
1
3
FOV
horizontal
0.0074 mm 640 × 100 mm ×
8 mm
---------------------------------------------------------------------
59.2 mm
= =
FOV
vertical
0.0074 mm 480 × 100 mm ×
8 mm
---------------------------------------------------------------------
44.4 mm
= =