Noise investigation for Optical Tweezers

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Noise Investigation for Optical Tweezers

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60Hz noise Investigation-next 5

slides

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60 Hz noise identification60Hz

#6

Data taken on may/18/2011

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Identification cont…

#660Hz

Data taken on june/02/2011

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Source identification and Solution• First source : AC power cables running close to the QPD signal wires• Second source: Power supply of on track was not grounded

Solution

• All the signal wires were rearranged and separated from AC wires• On track was powered by Ryobi lithium-battery

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Results

Data taken on june/30/2011

No 60 Hz noise

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Results No 60 Hz noise

Data taken on July/14/2011

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120Hz Investigation Onwards

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Noisy DOG Vs ideal DOG

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Ideal Data Vs Noisy Data

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Test for resonant frequency of the setup- next 17 slides

Sample plane

Tweezers structure

Tone generator

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Test-Results frequency Vs DOG-profileAt 0 Hz

#12

At 100 Hz #10

At 105 Hz #10

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Cont….

At 110 Hz#11

At 115 Hz

#11.5

At 120 Hz

#12

Resonance HIT

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Cont….At 125 Hz

#12.5

At 130 Hz#13

At 135 Hz

#13.5

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Cont….

At 150 Hz

At 140 Hz

At 145 Hz

#14

#14

#15

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Cont….At 160 Hz

At 170 Hz

At 180 Hz

#16

#17

#18

Another hit

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Cont….At 200 Hz

At 225 Hz

At 300 Hz

#20

#24

#30

Another hit

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Cont….At 350Hz

At 400 Hz

At 450Hz

Beating

Beating

Beating

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Cont….At 500Hz

At 550Hz

At 600Hz

Beating

Beating

Beating

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Cont….At 650Hz

At 700Hz

At 750Hz

Beating

Beating

Beating

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Cont….At 800Hz

At 850Hz

At 900Hz

Beating

Beating

Beating

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Cont….At 950Hz

At 1000Hz

At 1100Hz

Beating

Beating

Beating

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Last one..

At 2000Hz

Beating

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Power spectrum comparisonspeaker on optical table Vs chairOT chair

0Hz

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Cont….

cc

OT chair

120Hz

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Cont…

cc

At 180 Hz

OTChair

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Cont….chairOT

300Hz

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Cont….lastone

chairOT

600Hz

Noise detection in the data

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Data Analysis

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•Vibration transmissivity wise structure is most sensitive to 100 to 150Hz and more sensitive to the frequencies less than 400Hz.

•Power coupling from frequencies higher than 150Hz wise 295Hz is the strongest candidate.

•Airborne noise wise structure is most sensitive to frequencies less than 140Hz.

•120 Hz is the mechanical resonant frequency of the structure.

•180Hz and 295Hz are the secondary resonance.

Summary