QHY461M Pro
QHY461M Pro
The QHY461M PH is a high-resolution monochrome BSI (back-illuminated) CMOS camera designed for astrophotography. Let’s explore its impressive features:
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Sensor and Resolution:
- The QHY461M PH features the Sony BSI IMX461 sensor with a pixel size of 3.76μm x 3.76μm.
- The sensor size is 44mm x 33mm, resulting in an impressive 102 megapixels.
- Its large sensor area allows for capturing detailed images of celestial objects.
- The QHY461M PH is a monochrome camera, which means it records light intensity without color information1.
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True 16-bit ADC:
- The camera maintains an unaltered, true 16-bit analog-to-digital conversion (ADC).
- This ensures high-resolution sampling across its full well capacity.
- The result is excellent dynamic range and precision for accurate data acquisition1.
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Low Readout Noise:
- The QHY461M PH achieves remarkably low readout noise, ranging from 1e- to 3.7e-, depending on the selected readout modes.
- This low noise level is essential for capturing faint details in astronomical images1.
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Data Interface and Memory:
- The camera uses a USB 3.0 data interface for efficient data transfer.
- It also features an internal image memory of DDR3, 1 GB.
- The large memory buffer ensures smooth data handling during long exposures1.
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Quantum Efficiency and Dark Current Noise:
- The QHY461M PH achieves a maximum quantum efficiency of 90% at 450 nanometers.
- Its dark current noise is approximately 0.003e-/pixel/sec at -20°C.
- These features contribute to high sensitivity and accurate imaging1.
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Selectable Image Readout Modes:
- The camera offers four different readout modes, allowing users to choose the most suitable setting for their specific imaging needs.
- Additionally, a scientific PRO version with USB 3.0 and 2x10 Gigabit fiber optic interface is available: the QHY461 M/C PRO1.
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.
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.
Optimizing USB Traffic to Minimize Horizontal Banding
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.
A typical Periodic Horizontal Noise under certain USB_TRAFFIC values.
After Adjusting the USB Traffic to avoid the periodic horizontal noise.
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.
Advanced Functions
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 details at “Multiple Readout Modes and Curves” Part.
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 QHY600/268/461/411 use an innovative suppression technology that can significantly reduce the apparent level of such noise.
UVLO Protection
UVLO(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.
A typical Periodic Horizontal Noise under certain USB_TRAFFIC values.
After Adjusting the USB Traffic to avoid the periodic horizontal noise.
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.
Model | QHY461PH |
Image Sensor | SONY IMX461 BSI CMOS Sensor |
Pixel Size | 3.76um x 3.76um |
Color / Mono Version | Mono Only |
Image Resolution | 11760 × 8896 |
Effective Pixels | 102 Megapixels |
Effective Image Area | 44mm x 33mm |
Sensor Surface Glass | AR+AR Multi-Coating Clear Glass |
Full Well Capacity (1×1, 2×2, 3×3) |
50ke- / 200ke- / 450ke- in Standard Mode 80ke- / 320ke- / 720ke- in Extend Full Well Mode |
A/D | 16-bit (0-65535 greyscale) for 1X1Binning18bit in 2X2 19BIT in 3X3 20BIT in 4*4 software Binning |
Sensor Size | TYPICAL 3.4inch |
Read Noise | 1e to 3.7e (in HGC mode) |
Dark Current | Approx 0.003e/pixel/sec @ -20C |
Exposure Time Range | 50us – 3600sec |
Frame Rate |
2.7FPS @ 8BIT 1.3FPS@16BIT on USB3.0 2.7FPS @ 16BIT 6FPS @ 14BIT on 10Gigabit Fiber |
Shutter Type | Electric Rolling Shutter |
Computer Interface | USB3.0 |
Filter Wheel Interface | 4PIN QHYCCD CFW Port |
Built-in Image Buffer | 1GByte DDR3 Buffer |
Cooling System | Dual Stage TEC cooler(-35C below ambient with air cooling). |
Anti-Dew Heater | Yes |
Telescope Interface | – |
Optic Window Type | AR+AR High Quality Multi-Layer Anti-Reflection Coating |
Back Focal Length | 32.5mm |