Jose Luis Sirvent Jonathan Emery Student Meeting 12– February -2012
Loss of -3dB: ◦ Horizontal plane: Disk-Fiber mm ◦ Vertical plane: Fiber-Fiber misalignment 60um ◦ Angular tolerance: 0.5 deg ◦ Signal received ~ 0.37%
Signal appearance ◦ 30Khz ◦ mWpp
Loss of -3dB: ◦ Horizontal plane: Disk-Fiber mm ◦ Vertical plane: Width of the slides ◦ Angular tolerance ~ deg ◦ Signal received ~ 0.58%
3.1 Focuser with commercial components
Loss of -3dB: ◦ Horizontal plane: Fiber-Lens 7mm um ◦ Horizontal plane: Lens-Disk 2.23mm -+60um (Too small?) ◦ Vertical plane: Slits width ◦ Angular tolerance ~ +-2deg ◦ Signal received ~ 11% (Improvement > Factor 10!!)
Improvement of tolerances: ◦ Defocus Bigger spot size ◦ Horizontal Plane: Fiber - Lens 4.29mm +- ? ◦ Horizontal Plane: Lens – Disk 4.35mm um ◦ Vertical plane ~ +-2deg ◦ Signal received ~ 11% mm
Fit with sinusoid
Transmission (50mVpp)Reflection (80mVpp) Focuser 800mVpp
LASER DIODES Reception Expected dBm CompanyComponentClassMax Curr.Max Power (dBm)Max Power (mW)StabilityCommentsTransRefFocusCol OPTEKOPF372AGaAIAs LED100mA-100.1StableFine, Low Power KYOSEMIKLD085VCVCSEC12mA Stable LASER COMPPL85B002ST83-T-0 45mA6.985NoisyNoisy (Reflections) Last weeks PHOTODIODES CompanyComponentClassSensibility (dBm)Sensibility (mW)Saturation (dBm)Saturation (mW)Comment KYOSEMIKPGX1GGaAs PD-TIA E-03-- High-Pass filter F> 1Mhz KYOSEMIKPIX150M-H33Si PD-TIA E-04-- KYOSEMIKPIXAIG-T-STSi APD-TIA E-04-- OPTEKOPF562ASi PD E LASER COMPPDSIU500ST83-W-0Si PD E TIA Circ OK but F<2Mhz
Kyosemi Laser Components
Disk D=14cm 8796 slots of 50um ◦ Actual accuracy: 710 uRad. ◦ Specifications: 25 uRad. ◦ Needed Improvement of factor 30. How to reach specifications (Interpolation): ◦ 1.Offline Processing (Software requirements) ◦ 2.Online Processing (Possible by hardware)
Disk D=14cm 8796 slots of 50um ◦ Actual accuracy: 710 uRad. ◦ Specifications: 25 uRad. ◦ Needed Improvement of factor 30. How to reach specifications (Interpolation): ◦ 1.Offline Processing (Software requirements) ◦ 2.Online Processing (Possible by hardware)
2.Online Processing 1. Interpolation with previous cycle reference Source of errors: Bad measurement in previous cycle = interpolations errors in next. Allways there will be a delay of 0.5 cycle. Possible improvement: Histeresys when crosing zero.
2.Online Processing 2. Interpolation of Sin-Cos Encoders: Two fibers if working with Focuser (displaced 90deg) No errors or delay: Relationship between signals Variations in speed applied immediately. Interpolation Unit + Quadrature decoder