With the advantage of low readout noise and high-speed readout, CMOS technology has revolutionized astronomical imaging.  A colour, back-illuminated, high-sensitivity, astronomical imaging camera is the ideal choice for astro-imagers.

The QHY268C is a back-illuminated CMOS camera with true 16-bit A/D and 3.76um pixels.  This Sony IMX571 sensor is an ideal CMOS sensor exhibiting no amplifier glow. 16-bit A/D gives high resolution sampling of the whole full well range.  Digitizing 0-65535 levels yields a smooth image with continuous gradation of greyscale levels.

Note that since January 2023, the front end of the QHY268C has been made the same as its monochrome sibling, the QHY268M. The camera now uses six bolts to connect to the component next to it.

1GB DDR3 image buffer

In order to provide smooth uninterrupted data transfer of the entire 26MP sensor at high speed, the QHY268 has 1GB DDR3 image buffer. The pixel count of the latest generation of CMOS sensors is very high resulting in greater memory requirements for temporary and permanent storage.  The QHY268 has adopted a large-capacity memory of up to 1GB.  Data throughput is doubled. This large image buffer meets the needs of high-speed image acquisition and transmission of the new generation of CMOS, making shooting of multiple frames smoother and less stuttered, further reducing the pressure on the computer CPU.

Extended Full Well Capacity and Multiple Read Modes

With a pixel size of 3.76um, these sensors already have an impressive full well capacity of 51ke.  Nevertheless, QHYCCD has implemented a unique approach to achieve a full well capacity higher than 51ke- through innovative user controllable read mode settings.  In extended full well readout mode, the QHY268 can achieve nearly 75ke-.  Greater full-well capacity provides greater dynamic range and large variations in magnitude of brightness are less likely to saturate.

Native 16-bit A/D

The new Sony sensor has native 16-bit A/D on-chip. The output is real 16-bits with 65536 levels. Compared to 12-bit and 14-bit A/D, a 16-bit A/D yields higher sample resolution and the system gain will be less than 1e-/ADU with no sample error noise and very low read noise.

BSI

One benefit of the back-illuminated CMOS structure is improved full well capacity. This is particularly helpful for sensors with small pixels. 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.

Zero Amp Glow

This is also a zero-amplifier glow camera.

TRUE RAW Data

In the DSLR implementation there is a RAW image output, but typically it is not completely RAW.  Some evidence of noise reduction and hot pixel removal is still visible on close inspection.  This can have a negative effect on the image for astronomy such as the “star eater” effect.  However,  QHY Cameras offer TRUE RAW IMAGE OUTPUT and produces an image comprised of the original signal only, thereby maintaining the maximum flexibility for post-acquisition astronomical image processing programs and other scientific imaging applications.

Anti-Dew Technology

Based on almost 20-year cooled camera design experience, The QHY cooled camera has implemented the fully dew control solutions. The optic window has built-in dew heater and the chamber is protected from internal humidity condensation. An electric heating board for the chamber window can prevent the formation of dew and the sensor itself is kept dry with our silicon gel tube socket design for control of humidity within the sensor chamber.

Cooling

In addition to dual stage TE cooling, QHYCCD implements proprietary technology in hardware to control the dark current noise.