Inspection Camera Z.C. Liu, Z.Q. Li, D. Li, J. Gao IHEP

Inspection cavity type  1.3GHz single cell elliptical cavity  1.3GHz multi-cell elliptical cavity  Low frequency elliptical cavity like 500MHz, 650MHz…  Other type like spoke cavity…

Inspecting what?  Equator welding seams  ~3-6 mm wide  Iris welding seams  ~3-6 mm wide  Pits, cratches…  Multi-tens or multi-hundreds microns A resolution of multi- microns is needed for the inspection system

Support tube Sketch map Camera lens 2x lens +1 close-up lens Mirror Monitor Linear rail table Holding cavity Cavity moving direction

Image precision analyzing Focal length （ mm ） Precision （ um/pixel ） （ 21 million pixels camera ） 0.9m1.3m1.5m1.8m2m2.2m Camera + long focal length lens + 2x lens: Note: 1 ） ”-” can not form an image 2 ） Blue:equal to kyoto camera (7.5-15um/pixel);Red:higher than kyoto camera. 3 ） Long focal length lens: SIGMA APO mm F DG OS HSM. 4) The image precision will be increased while using +1 close-up lens, for example, with +1 close-up lens and a 500mm focal length, the precision is 0.64um/pixel at 550mm away from the camera CCD. However more lens the picture sharpness more worse.

Light system 1) It is not easy to get a good picture by only changing the brightness of the light in region 1 2) It is easy to get a good picture in region 2 and 3 Too bright Good ① ② ③ Light Camera position Mirror-like surface

Light system 1) It is easier to get a good picture by changing the brightness of the light in region 1 than without ground glass 2) It is easy to get a good picture in region 2 and 3 Bright Good ① ② ③ Light Camera position Ground glass Mirror-like surface

Light system 1) It is not easy to get a good picture at a position for the whole inspection area. Bright Good Light Camera position Ground glass Rough mirror-like surface Bright

Light solution  Tunable terms  Light brightness  Light angle  Light source  Light spectrum  Solution:  Light brightness Ground glass, paper, reflection  Point –like light source Led light  Light source movable

Light system 1) moving the light source to an angle with no direct reflection from the inspection area to the camera. 2) Reflection light from different material will be tested as light source 3) take different light angle pictures to form a composite one. Bright Good Light Camera position Ground glass Or paper etc.. Rough mirror-like surface Bright

Image of plane picture without close-up lens 1mm 200um

Image of iris without close-up lens 1mm A resolution of 9um/pixel. 200um

Cost of the system Cost($) Camera and lens5500 Support and transfer system25000 Small parts500 Total31000

Problems need to be solved  The camera is shaking while taking pictures even with tripod.  The sharpness of the image need to be improved.  Light system need to be improved for equator inspection  The real resolution of the system now is only about half of the calculation results.  Using close-up lens.

Acknowledgement Many thanks to the support of the ILC group leader J. Gao. And thanks for the help of the people in the ILC group.

Thank you!