Table of Contents
Advertisement
When evaluating the responsivity of the camera, set the exposure time to the maximum allowable
for the system, minus any margin required for illumination degradation, if applicable. The line rate
during evaluation is not critical and can be internal or externally triggered as long as its period
does not violate the above rule.
Note that when adjusting the exposure time, a momentary loss of LVAL will occur. This will also
happen when changing user sets that include exposure time.
Measuring Exposure Time
See the section Camera Control Category in Appendix A for GenICam features associated with this
section and how to use them.
Relevant Feature: Measured Exposure Time, Refresh Measured Exposure Time
The camera has the means to measure the exposure time that is currently being internally
generated. This is not a continuous reading but a one-time measurement that needs to be initiated
by the user through issuing a Refresh Measured Exposure Time command.
Adjusting Responsivity
See the section Camera Control Category in Appendix A for GenICam features associated with this
section and how to use them.
Relevant Features: Row Selector, Gain Selector, Gain
It is desirable for camera performance to always use the maximum exposure time possible based
on the maximum line rate of the inspection system and any margin that may be required to
accommodate illumination degradation. However, it will be necessary to adjust the responsivity to
achieve the desired output from the camera. The camera has a row selector feature and a gain
feature that can be used to make the necessary adjustment to the responsivity.
Three Row Selections are available: 4 rows, 8 rows, and 12 rows.
4 rows are useful when there is plenty of light and the inspection system needs to extract
•
low contrast defects from bright image backgrounds. By only using four line rows a higher
full well can be achieved (more electrons collected in a pixel for a given integration period)
and an associated higher signal to noise performance (i.e. less shot noise).
8 rows offer the highest responsivity at the highest line rate. It is optimized for light starved
•
inspection systems where low contrast defects must be extracted from dark images and
where the dark noise level needs to be minimized (i.e. minimizes Noise Equivalent
Exposure).
12 Rows are useful for light starved inspection systems but at a maximum line rate less
•
than 8 Rows. This may be useful for lower performance or cost sensitive systems where less
intense, lower cost, illumination is used.
A single gain adjustment is used for any of the row configurations. Gain can be adjusted from
0.65x to 5x (Extended Gain Range Enabled), depending on the number of rows selected. Using row
selection and gain adjustment the camera's responsivity can be changed by a factor of 23x—from
lowest to highest responsivity performance.
When evaluating responsivity, it is best to start with four rows and then move to a higher number
of rows if the resulting responsivity does not meet your application's requirements.
The Piranha XL Camera
• 25
Advertisement
Table of Contents
