1. Performance of Fibers in IFU
2.4m Telescope Group
Yunnan Observatory of CAS
Performance of Fibers in IFU
Chang, Liang
LIA Origins IFU

2. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS
Main Missions
1. Focal Ratio Degradation
2. Scrambling Properties
LiJET
FASOT ?
IFU on 2.4m telescope ?

3. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS
Gerardo Avila-----ESO
Focal Ratio Degradation (FRD)
Why???
The main reasons:
The high sensibility of the fibers to any mechanical constraints
The preparation of the fiber ends and the optical alignment errors
How???

4. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS

5. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS

6. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS

7. FRD of LIJET Fibers 2.4m Telescope Group Yunnan Observatory of CAS
①Laser ②Objective③lens1 ④Iris ⑤Lens2
⑥Fiber ⑦Iris2 ⑧Lens 3 ⑨Power meter
Total Transmission
F/4 output
Transmission
F/4 FRD
105um
405nm
53.67%
51.94%
96.77%
543.5nm
94.75%
90.53%
95.54%
632.8nm
95.27%
94.18%
98.85%
50um
44.59%
41.16%
92.3%
86.73%
86.21%
99.4%
92.51%
91.94%
98.95%

8. Yunnan Observatory of CAS PSF Position and profile changed on CCD
2.4m Telescope Group
Yunnan Observatory of CAS
2. Scrambling Properties
What’s:
When we use fiber to connect telescope and spectrographs, our requirement imposes position
stability along the dispersion of the monochromatic image of the fiber (PSF)
The position errors of barycenter of the PSF are mainly produced by the stability of telescope
guiding system and seeing
Position of the star in front of the fiber is not constant
PSF Position and profile changed on CCD
Optical fiber are not perfect image scramblers, indeed, the information of position of star in front of a fiber is not totally lost at output end, The light on fiber surface is not evenly distributed

9. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS
How Increase Scrambling Properties of Fibers
Optical methods and mechanical methods

10. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS

11. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS
Mechanical Methods
Pressure, Bending, twists, shake, freeze??

12. Yunnan Observatory of CAS
2.4m Telescope Group
Yunnan Observatory of CAS
The End
Thanks