Sensor; Sensor Sizes; Fill Factors - IDS uEye series User Manual

User Manual uEye Cameras V3.32
6.2

Sensor

6.2.1

Sensor Sizes

The size of a digital camera sensor is usually specified in inches. However, the specified value does
not indicate the actual size of the active sensor area. The sensor size specifications date back to
the formerly used tube systems: The curvature of the imaging surface of the camera tube caused
distortions to the display, reducing the usable capture area of a 1" tube to a rectangle with a diagonal
of 16 mm.
With the introduction of the semiconductor sensor technology, the dimensional specifications were
taken over from tube systems. For this reason, a sensor whose active area diagonal measures 16
mm is specified as a 1-inch sensor. The following illustrations show the most common sensor sizes.
The size of each single sensor cell (pixel) depends on the size of the active sensor area and the
resolution. In general, less pixels over the same sensor area (or a larger sensor area with the same
resolution) will result in greater photosensitivity of the sensor.
6.2.2

Fill Factors

The fill factor is the percentage of the pixel area that is exposed to light during exposure. Ideally this
would be 100%. Since other elements are located on the sensor surface besides the light-sensitive
photodiodes, this value may be reduced to approx. 30 - 50%, depending on the sensor technology.
The use of micro lenses compensates for this and increases the fill factor to 90% or more. Micro
lenses collect the light that falls onto a photocell, thus increasing the useable sensor area.
Figure 27: Using micro lenses to increase the effective fill
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Figure 26: Comparison of different sensor sizes
factor
© 2009 IDS Imaging Development Systems GmbH