QSI 520c Guía de usuario descargar pdf (Pagina 17)

QSI 500 SERIES USER GUIDE

Cooling the Camera

Cooling the CCD is essential for successful astro-imaging. Cooling dramatically reduces the

dark current and resulting thermal noise in an image and makes long exposures practical.

See the discussion in the 'CCD Imaging Overview' Section on dark current and noise.

QSI 500 Series cameras use a very efficient thermo-electric cooler (TEC) which relies on

ntial cooling and the colder the

e TEC,

eries cameras employ two different methods for removing this heat.

Standard Air Cooling

The back of a QSI 500 Series camera acts as a large heatsink with cooling fins machined

directly into the body. Two automatically controlled cooling fans force air through these fins.

The movement of air through the cooling fins greatly increases the amount of heat removed

from the camera.

Keep in mind that the lowest temperature that the CCD can be cooled is limited by the

ambient air temperature and the speed of the cooling fans. Achieving very low temperatures

is easy when imaging outdoors during cooler weather. If it is particularly cold you may not

even need to turn the fans on. If the weather is warm and humid you may not be able to

ol the CCD to the desired temperature. See the specifications for your camera to

rmine the maximum cooling differential you can expect under typical conditions.

Liquid

Forced

needed els of cooling.

Howev

deman

be ach

Exchan utilizes

recircul

of heat

equal, th

to 10ºC

rear of

image to the right. The water flows through

oses, colored blue in this picture.

lf-sealing quick-disconnect couplings are

used to

the hos

leakag

There plying recirculating water for the camera. One of the

simpler and more common methods for astro-photography is to place a small submersible

pump into a 5 gallon plastic pail full of cool water. The temperature of this amount of water

the 'P

eltier Effect' to cool the CCD. When power is applied to a TEC, one side of the device

gets cold and other side gets hot, essentially pumping heat from the cold side to the hot

side. All QSI 500 Series cameras employ a two-stage TEC to increase the differential

cooling effect.

The more power applied to the TEC, the greater the differe

CCD can get. The heat pumped from the CCD, as well as the power dissipated by th

creates a significant amount of excess heat that must be removed from the camera. Q

500 S

dete

-Assisted Cooling

air cooling is usually all that is

to reach normal lev

er, in warm weather or particularly

ding situations, additional cooling can

ieved with the optional Liquid Heat

ger, or LHX. The LHX

ating water for more efficient removal

from the camera. All things being

e LHX can provide an additional 7ºC

of CCD cooling. It attaches to the

the camera body as illustrated in the

the two h

attach the hoses to the LHX so that

es can be removed easily without

e of the recirculating water.

are numerous ways of sup

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QSI 520c Guía de usuario Pagina 17

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