Infrared spectroscope for electron bunch length measurement:

Heat sensor parameters Analysis

Gilles Dongmo – M.SULI Presentation August 11, 2011

The detector

The detector used for the project is a piezoelectric detector made of Lead Zirconate Titanate (PZT)

128 pixels arranged over 14.3 mm

The printed board circuit

The detector is mounted to a printed circuit board

Pin 3 of the synchronization connector out puts a pulse

The connector TP3 out puts the signal response of the detector

Power connector USB connector

Synchronization connector (pin 3) Sensor connected

Output detector signal

The initial data collected

0 20 40 60 80 100 120-10

90

190

290

390

490

590

690

790

890

RMS signal and signal brightness per pixel at 210Hz

rms databrightness data

background rms

pixel number

brig

thne

ss

The detector is lit at the middle pixels

maybe the detector was sending out an inverted signal.

Pixels 68 and 95 are dead.

What type of noise do we have to deal with?

0 50 100 150 200 2500

100

200

300

400

500

600

700

800

900

rms data and average brightness for the whole frequency range

rms brightness

frequencies (Hz)

brig

htne

ss (u

V)

Data were recorded for frequencies up to 250 Hz

The signal to noise ratio was found to be high

We get an average signal to noise ratio of 43.3

The detector is not very sensitive to the room’s light and other background noise.

Data collectionThe read rectangles

represent the maximum and minimum values averaged over 12 sampling

The green line is the current reading.

Some pixels are dead.How is the software using

the raw data?

Dead pixel

The AC-Coupling issue

The next step was to try to figure out what type of data were actually collected by the detector which meant we had to understand how the data were collected.

We were able to write a program replicating the data received by the software. The algorithm they used did not seem to present any issue if the data the detector was outputting was the light intensity read by it when the light was on and off

Tape at the middle of the detector

0 20 40 60 80 100 120 1400

5

10

15

20

25

220Hz with centered tape data comparison

software data

rms

pixel

max

imum

inte

nsity

(mv)

0 20 40 60 80 100 120 1400

5

10

15

20

25

240Hz with centered tape data comparison

software datarms

pixel

max

imum

inte

nsity

(mv)

Dead pixel reading

Intensity of the signal

0 20 40 60 80 100 120 1400

5

10

15

20

25

240Hz with centered tape data comparison

software datarms

pixel

max

imum

inte

nsity

(mv)

0 20 40 60 80 100 120 140

-80

-60

-40

-20

0

20

40

60

80

100

120

140

160

LED rate of 240Hz data compar-ison

software datarms

pixel

max

imum

inte

nsity

(mv)

Detector’s response time

Generated signal and integration time. On this graph from the detector’s user’s manual, the integration time covers most of the signal period both the on and off phase.

Dead time

The integration time dataExperimental integration time Calculated integration time

frequencies (Hz) VDR time (us) delay (us)

240 375 0

240 400 74

240 646 258

230 800 350

220 1000 494

210 1200 634

201 1400 1270

197 1500 over

129 4000 over

frequencies (Hz) VDR time (us) integration time (us)

240 375 3788.666667

240 400 3763.666667

240 646 3517.666667

230 800 3544.826087

220 1000 3542.454545

210 1200 3558.904762

201 1400 3572.124378

197 1500 3573.142132

129 4000 3748.937984

Comparison of the integration times

120 140 160 180 200 220 240 2600

500

1000

1500

2000

2500

3000

3500

4000

Comparison of the integration time and delay time

integration timedelay time

frequencies (Hz)

time

(us)

The plot shows the calculated integration time is very constant over this range frequencies.

The delay drops with frequency

The equipment setup

Single cell detector and Infrared laser

Single cell piezoelectric detector.

Sensitivity calculated to be 1.34 micro-amps per watt.

This was done with the red HeNe laser.

Sensitivity calculationThe amount of power

generated by the laser was recorded using a power meter

The chopper wheel created the pulse

The lens focused the beam as much as possible

Current output determination

AcknowledgementsThis was done with the appreciated contribution of:

Josef Frisch Alan Fischer Kiel Williams Julie Cass

Mark Petree Georges Burgueno

Tonee Smith The Department of Energy

SLAC & SULI staff

Thank you!!