QHY QHY268M Pro I Mono Cooled CMOS Camera

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QHY CMOS Scientific Cameras for the Ultimate in Imaging Performance

QHYCCD Scientific Cameras offer the latest technology in scientific imaging at reasonable prices. Scientific CMOS image sensors offer extremely low noise, rapid frame rates, wide dynamic range, high quantum efficiency, high resolution, and a large field of view simultaneously in one image. In this sense, while QHYCCD cameras made for astronomy clearly fit the definition of scientific cameras, we differentiate our scientific camera models based on additional features not found on similar models used for astro-imaging.

QHYCCD Scientific Cameras not only exhibit extremely low noise, high quantum efficiency and other scientific CMOS characteristics, but also offer large area, high-resolution sensors, SWIR sensors, polarized light sensors, GPS enabled timing, external triggers, field programmable gate arrays, a 2x10GB fiber optic computer interface and water cooling options.

The QHY268M Pro I houses a SONY IMX571 APS-C format CMOS sensor inside it's well-built, cooled body. The IMX571 is back-illuminated with a total of 26MP, a pixel size of 3.76um, and native 16Bit ADC. This camera has a quantum efficiency of 91%, low readout noise of 1.1e, and a full well capacity of 75ke.

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The QHY268M Pro I Has an Amazing Array of Features!

NATIVE 16BIT 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. 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.

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.

ZERO AMP GLOW: This is also a zero amplifier glow camera.

COOLING & ANTI-DEW CONTROL: In addition to dual stage TE cooling, QHYCCD implements proprietary technology in hardware to control the dark current noise. 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.

SEALING TECHNOLOGY: Based on almost 20-year cooled camera design experience, The QHY cooled camera has implemented the sealing control solutions. The sensor itself is kept dry with our silicon gel tube socket design for control of humidity within the sensor chamber. By the way, there’s no oil leaking.

Compared to other astrophotographic products, the scientific “Pro” grade vesion has more interfaces, more functions, and higher quality to cater for the complicated needs including but not limited to: Sky Survey, Astronomical Photometric, high-resolution LCD/OLED screen inspector/color calibration. All-sky camera. Scientific Measurement, DNA sequencer, Spectrum Instrument.

A Pro scientific grade camera has the following interfaces or functions:

USB3.0 is a very popular interface and very easy to use. USB3.0 can not support a transfer distance of more than 3 meters. If you want to get a long-distance under USB3.0, QHYCCD supplies the optional 5-meter and 10-meter USB3.0 extender cable with a built-in amplifier.

The built-in 2*10Gbps fiber socket can work with the QHYCCD PCIE2.0x8 data grabber card (sold separately). The fiber interface is for the requirement of the professional obs. It will give the following advantages than the USB3.0 interface. Then what is the benefit of the Fiber Interface?

• Higher Data Rate: One 10Gigabit Fiber can transfer maximum 10Gbps data. The actual data rate can get about 800MBytes/s. While the USB3.0 is 5Gbps and the actual data rate is about 350MByte/sec. Use the two 10Gigabit fiber can get about 1.6GBytes/s speed. The IMX455 sensor has the high-speed mode like the 10FPS 14bit full resolution mode and 30FPS 8K VIDEO mode. The data rate of these modes is much more than USB3.0.

• Very Long Transfer Distance: The fiber is hundreds of times longer than USB3.0. USB3.0 can only transfer 3meter to 5meter. For longer distances, it needs the extender cable but can just get 10meter to 15metes. While the fiber can transfer 300meter directly by default optic module; with the long-distance optic module, it can transfer up to 40km.

• Solid, Stable and Not Affected by EMI: One major factor that causes the camera to hang is the EMI issue. The USB3.0 transfer maybe gets effect by the EMI in the transfer patch. Like the static and other high-power device emitted. The EMI will cause the transfer data packet to get a CRC error and cause the image loss. A long USB cable is easier to get this problem. Light can not be affected by the EMI. So with the fiber transfer, it will get everything very stable.

There is a 6pin GPIO socket on the camera backside. It can be configured into different modes, or customized as the user requests to meeting more complex timing by re-programming the FPGA.

Multiple Readout Modes are special for QHY 16-bit Cameras (QHY600/268/461/411). Different readout modes have different driver timing, etc., and result in different performance. See the graphs in the image rotator for more information.

You may find some types of thermal noise can change with time in some back-illuminated CMOS cameras. This thermal noises has the characteristic of the fixed position of typical thermal noise, but the value is not related to the exposure time. Instead, each frame appears to have its own characteristics. The QHY268 use an innovative suppression technology that can significantly reduce the apparent level of such noise.

UVLO, or Under Voltage Locking, is to protect the electronic device from damage caused by abnormally low voltages. Our daily life experience tells us that the actual operational voltage of an electrical device must not significantly exceed the rated voltage, otherwise it will be damaged. For such precision equipment as cameras, long-term work at too low input voltage can also be detrimental to the working life of the camera, and may even make some devices, such as power manager, burn up due to long-term overload. In the all-in-one driver and SDK after 2021.10.23 stable version, the camera will give a warning when the input voltage of the camera is below 11V.

It is common behavior for a CMOS sensor to contain some horizontal banding. Normally, random horizontal banding can be removed with multiple frame stacking so it does not affect the final image. However, periodic horizontal banding is not removed with stacking so it may appear in the final image. By adjust the USB traffic in Single Frame mode or Live Frame mode, you can adjust the frequency of the CMOS sensor driver and it can optimize the horizontal banding appeared on the image. This optimized is very effective to remove the periodic banding in some conditions.

The camera is designed to use the +12V to reboot the camera without disconnecting and reconnecting the USB interface. This means that you can reboot the camera simply by shutting down the +12V and then powering it back on. This feature is very handy for remote controlling the camera in an observatory. You can use a remotely controlled power supply to reboot the camera. There is no need to consider how to reconnect the USB in the case of remote control.

QHY268M Pro I Quantum Efficiency

QHY calculated the absolute QE of the IMX268M sensor and concludes that the QE at OIII is at least 87%. The peak QE of the IMX268 is at least 90% and the absolute QE curve of QHY268M ranges from 400nm-1000nm. For more on QHY's QE calculations of the sensor used in the QHY268M, please see Measuring the absolute QE of the QHY268M.

QHY268M Pro I Readout Noise

Multiple Readout Modes are possible in QHY 16-Bit cameras like the QHY268M Pro I. Different readout modes have different driver timing, etc., which results in different performance parameters. Note the various readout noise curves for different readout modes, such as Photography DSO Mode, Photography DSO Mode 2CMS, High Gain Mode, High Gain Model 2CMS, Extend Fullwell & Extend Fullwell 2CMS.

QHY268M Pro I System Gain

Compared to 12-bit and 14-bit A/D, the QHY268M Pro I, with 16-bit A/D, yields higher sample resolution and the system gain will be less than 1e-/ADU with no sample error noise. As with the Readout Noise chart (found in Images section above), note the various curves based on which Mode you choose.

QHY268M Pro I Dynamic Range

In Extended Fullwell Mode 2, the QHY268 can achieve nearly 75ke-. Greater full-well capacity (see chart below) provides greater dynamic range, and large variations in magnitude of brightness are less likely to saturate.

QHY268M Pro I Fullwell

The QHY268 offers Extend Fullwell 2CMS mode. According to QHY, they recommend the 2CMS modes for astrophotography since they can reduce readout noise by secondary sampling while keeping the same full well value and system gain.