1. The 5th HERD Workshop, CERN IsCMOS Camera Developement
&
Mechanical design
Good afternoon, everyone. My name is li yong, from xi’an institute of optics and precision mechanics of cas,China. Now I’m glad to give a simply presentation of our ISCMOS camera and its mechanical design.
Li Yong, XIOPM
, CERN

2. Outline Background IsCMOS Developement Mechanical Design
What to Improve
Next to do

3. IsCMOS is the calorimeter’s readout system of HERD.
Background
IsCMOS is the calorimeter’s readout system of HERD. ＋
About 7500 cubes of LYSO crystals，
2 outputs for every LYSO crystal to IsCMOS
I think there is no need to mention HERD program any more. I’ll just talk about ISCMOS camera. As you can see in the picture, IsCMOS is the calorimeter’s readout system of HERD program. There will be 4 cameras on the payload.

4. IsCMOS Developement Requirements :
Spectral response range: 450nm～600nm
Sensitivity: 100 photon/µs
Max frame rate: ～500fps
Dynamic range ：＞200(actually achieve: 1000+)
Power consumption: 36W
The signals send out from calorimeter is weak and sometimes very fast, and they have a large energy range. To read out the signals, Iscmos need be sensitive enough, fast enough and have a large dynamic range. Here is the main requirements of the camera, sensitivity, dynamic range and frame rate.

5. IsCMOS Developement High frame rate and large area sCMOS Cathode Gated
Intensifier
Fiber optical taper
High frame rate and
large area sCMOS
The basic components include the Cathode gated intensifier and high frame rate scmos, which Coupled by a fiber optical taper. Just like ICCD.

6. IsCMOS Developement
2013
2015
2014
2012
From 2012 until now, we have made 4 generations of ICCD and 1 IsCMOS.
2017
From 2012 until now, we have made 4 generations of ICCD and 1 IsCMOS prototype. In 2015’s beam test we use 2 ICCDs to read out the signals, by analyzing the datas we found it is not good enough. There are some problems, such as spot tail, inefficient dynamic range(later my colleague will talk about it with more detail). So we change it with scmos this time to make a iscmos camera with a higher performance.

7. Two stage fiber optical taper coupling
Fiber interval
First stage FOT
Second stage FOT
IIT
active area
fiber
Energy transmission efficiency
Size of Selected Devices
Performance of Selected Devices
Number of Coupled WLSF
About 7,500 LYSO crystals, each IsCMOS should be coupled about 3,700 fibers.
Considering Energy transmission efficiency, Size and Performance of Selected Devices, number of coupled wavelength shifting fibers, after calculating, we had a new scheme: two stage fiber optical taper coupling. We have two optical taper and Taper 1 is 3 times larger than taper 2, then it can be coupled with about 3700 fibers on camera, two camera for 7500 fibers. The total minification is about 9:1.
Taper1: φ120 (2.92:1)
Taper2: φ40 (3.04:1)

8. Mechanical Design Taper Coupling Unit.
Ok, earlier my co-worker have given the report of test result. Next I’ll talk about the mechanical design of iscmos camera. The most important unit is taper coupling unit. It is composed of taper 1, image intensifier, taper 2 and scmos.

9. Coupling gap is about 10µm.
Taper Coupling
Coupling gap is about 10µm.
Each component is fixed tightly in its holder with clamp pad or nut and silicon rubber. Then we adjust each flange with a optical alignment device to make the flange surface parallel to the optical surface. Then the components are assembled together in sequence. We adjust the thickness of the pads between the flanges to make the gaps between the coupling surfaces right according to the image of the resolution target. we can see it from detector softeware. According to some experiments and calculating, the proper gap is about 10μm(micron).

10. Cooling Design
The lowest temperature can be controlled at 18℃±0.1℃ in lab in about 22℃.
Another unit need to pay attention to is the cooling system of scmos. To get high signal nose rate, we use a TEC model and a radiating tube unit to cool the scmos, with a PID controller, the lowest temperature can be controlled at 18℃ in lab in about 22℃. To protect the opened detector from condensate water, we use some silicon rubber to protect the golden silk and make it sealed from air.

11. What to improve
Improve coupling technology to achieve higher energy transmission efficiency
Improve cooling design to get a lower temperature of sCMOS
Improve the stability of system
Improve the system to get higher sensitivity and larger dynamic range ……
According to the test this time, I think we still have something to do to improve the iscmos system.

12. Next to do Improve design of Iscmos system for payload
Mechanical and thermal design for space enviroment and ground test
So next we will …………

13. Next to do Size: 300mm(W)*300mm(H)*400mm(L) Weight: ~20kg
Power consumption: ~70W
electronic connectors and thermal exchange pads only located in front panel
This is the flight module for the payload, we change the mechanical design to let it suitable for replacement in space. Size…,weight…,power consumption…, from the picture, you can see electronic connectors…, that’s still in studying.

14. Next to do
The life of the IsCMOS is about 3.3 years. Replacement operation is necessary. Two plan:
1. IsCMOS is replaced totally by mechanical arm which is controlled by Astronaut in cabin.
2. IsCMOS is replaced totally by Astronaut outside the cabin.
Why we need to replace the ISCMOS, because its life is about 3.3 years limited by the image intensifier. So we have two plan to replace them:
1………
2………
That means we have to design a simple and reliable connectors and quick lock unit to do the job. That’s next to do.

15. THANKS!