The ASI461MM Pro is a cooled monochromatic camera for very demanding astrophotographers and astronomical research!
It uses the 44 x 33 mm Sony IMX461 CMOS chip with 100 megapixels and a resolution of 11656 × 8750 pixels. Thanks to back-illuminated technology, the sensor is particularly sensitive.
BSI, back-illuminated CMOS structure:
One benefit of the back-illuminated CMOS structure is improved sensitivity. In a typical front-illuminated sensor, photons from the target entering the photosensitive layer of the sensor must first pass through the metal wiring that is embedded just above the photosensitive layer. The wiring structure reflects some of the photons and reduces the efficiency of the sensor.
In the back- illuminated sensor the light is allowed to enter the photosensitive surface from the reverse side. In this case the sensor’s embedded wiring structure is below the photosensitive layer. As a result, more incoming photons strike the photosensitive layer and more electrons are generated and captured in the pixel well. This ratio of photon to electron production is called quantum efficiency. The higher the quantum efficiency the more efficient the sensor is at converting photons to electrons and hence the more sensitive the sensor is to capturing an image of something dim.
Two-stage cooling: An integrated thermoelectric cooler (TEC) keeps the sensor up to 35°C below the ambient temperature. At 0°C, the dark current noise is only 0.003 e/s/Pixel. This means that an exposure time of 300 seconds only causes a dark current of 0.7 electrons. This is below the readout noise of the camera! At –20°C, the noise drops below 0.00024e/s/Pixel – so even 5-minute exposures remain virtually noise-free
Anti-Fog Function: On clear nights, the front glass of the camera cools down significantly; humidity condenses as dew and ruins your shots. A wafer-thin polyimide heating foil warms the glass just enough to prevent condensation. This "Anti Dew Heater" requires about 5 watts and can be switched off when you need to save power.
No Amp Glow
Traditional CMOS sensors produce a weak infrared light source during operation, which is quite often seen in the corner of uncalibrated images. This is the tell-tale signs of "amp glow". As the ASI461MM Pro uses zero amp glow circuitry, you won't have to worry about amp glow even when using high gain, long exposure imaging.
Note: This technology has already been implemented in firmware. No software operation is needed.
Colour or mono? Black and white cameras have the advantage of higher sensitivity and resolution than colour cameras. However, more effort is required to obtain a colour image. You also need colour filters and a filter wheel
