Optical, Mechanical, And Thermal Considerations; Mechanical Interface - Dalsa Piranha 2 Series User Manual

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Optical, Mechanical, and
Thermal Considerations

4.1 Mechanical Interface

The cam era's electronics are hou sed in a ru gged ized lightw eight alu m inu m case.
Mounting
The cam era can be m ou nted u sing the M3 holes (m etric-thread ed ) on its base or top, and
on its front plate at the corners.
Environment
The cam era and cables shou ld be shield ed from environm ental noise sou rces fo r best
operation. The cam era shou ld also be kept as cool as possible. The specified operating
tem peratu re is 10–50°C m easu red at the front plate, (the correspond ing am bient
tem peratu re range w ith still air is 0°C to 37°C). Mou nting holes (refer above) allow you to
attach heat sinking.
Thermal Management
For any CCD cam era optim al perform ance is achieved by transferring heat aw ay from the
sensor. Keeping a sensor ―cool‖ red u ces the am ou nt of d ark cu rrent ge nerated . Dark
cu rrent is the lead ing contribu tor to FPN , PRN U, d ark offset, rand om noise and other
perform ance specifications, especially w hen a cam era is significantly gained (i.e. +10d b).
Generally, d ark cu rrent d ou bles for every 7°C increase in tem perat u re at the sensor and
increases linearly w ith integration tim e. Fu rther variations in d ark cu rrent cannot be
com pensated for w ith ou r flat-field correction algorithm s. For this reason, at high gains
(+10d B), high tem peratu res (40°C front plate), and low line rates, it is recom m end ed that
you recalibrate the flat-field coefficients w hen the tem peratu re shifts by ±10°C.
N ote: Upon initial pow er-u p the front plate cam era tem p eratu re is near am bient. It is
recom m end ed to perform flat-field correction once the cam era gets w ithin 10°C of its
stead y state tem peratu re. For Piranha 2, at an am bient tem peratu re of 25°C and w ith no
airflow , the cam era takes 90 m inu tes to achieve stead y state and 20 m inu tes to reach
w ithin 10°C of stead y state. If you r system cannot perform flat-field correction after
w arm -u p consid er the recom m end ed m ethod s of red u cing d ark cu rrent and overall
cam era tem peratu res (see below ).
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