An Edge Sensor Design for the TMT - Thirty Meter Telescope

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TMT.CTR.JOU.06.002.REL01 Electronics Overview Sensor 1 of 6 shown Mirror Sensor Electronics 1 of 123 Sensor Connector for drives 6 ea. A B C Sensor Charge Electronics at Sensor contains: Preamp Shaper Amp Driver Goal 300 mw Position and Tilt Sensor Analog Gap Calib Pulse DC Power Gap Connector 6 PreAmps Electronics at Mirror Support for 6 sensors contains: 6 ADCs 6 DAC sets 1 FPGA Sensor data Oscillator Sync Read/write Drive 1 Drive 2 Connector 6 drive sets Electronics at Sensor Pre-Amplifier RC(CR)2 Shaping Amplifier ~ 4 micro-seconds Cable driver A B Sensor Analog Sensor Charge Calibrated Capacitor +/- 6 V DC to all DC Power Gap Calib Pulse
TMT.CTR.JOU.06.002.REL01 Electronics at Mirror B Sensor Analog 6 ea Sensor Support, BLC and ADC ADC 16bit DC Power ADC & BLC Timing Gap Calib Pulse 6 ea 6 ea Sensor Drive Generation 6 set SW Gap Drive 1 6 ea Gap Calib DAC 1 ea Gap DAC 1 ea Offset DAC 6 ea 0.1 VGMax to –0.1 VGMax R/W R/W R/W FPGA Contains: 1 Generation of Switch Control for position/tilt, gap, & gap calibration 2 R/W to DACs 3 Generation of 10kHz 4 Timing of ADC 5 Integration of all pulses in 20 Hz readout period 6 Capture & integration of fast data stream (400Hz) 7 Readout of sensor position/tilt and gap data 8 Readout out of gap calibration pulse C Sensor data Oscillator Sync Read/write Drive 2 Position and Tilt 6 ea Gain DAC 1 ea 0 to VGMax Switch Control R/W DC Power Range Using standard fixtures we will measure the position of the plates with respect to the reflecting surface after each sensor is attached to the segment. The initial offset voltages will be determined using these measurements. We assume the rms measurement error is 10 microns. To accommodate measurement errors and allow the phasing measurement to “capture” all segments, we assume the electronics requires a full range (in possibly a “coarse” mode) of ±30 microns. Linearity We assume the non-linearity to be dominated by the non-linearity in the final ADC. Non-linearity caused by fringe fields and substrate dielectric constant is negligible. Commercial ADC’s with 16 bits advertise a non-linearity of
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An Edge Sensor Design for the TMT - Thirty Meter Telescope

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