Electronic Design of an

canolaokahumpkaElectronics - Devices

Nov 2, 2013 (3 years and 7 months ago)

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Electronic Design of an
Acousto Optic Tunable All
Fiber Spectrometer

Tanuja A. Mouli


Faculty Mentor: Professor
Henry P. Lee

Graduate Student: Fares
Alhassen


The Project: Big Picture

Unknown
Wavelength

Acousto Optic Tunable Filter


(AOTF)

Metal Frame

Optical
Fiber

PZT

AOTF: The PZT


(Piezo Electric Tansducer)

AC


Aluminum cone is
attached to PZT
disk


When AC voltage
is applied, the
cone vibrates up
and down

CONE

PZT

The AOTF

PZT and horn

Acoustic wave

RF

(Piezo Electric Transducer)


When PZT vibrates, it creates a micro
acoustic wave


Tunable filter is created by changing the
frequency of PZT

AOTF: Notch Filter


Acts to pass wide
range of
frequencies


While attenuating
narrow band of
frequencies

AOTF

PZT

Aluminum
Cone

Why use AOTF?


AOTF is easily tuned and can be
controlled electronically


Optic fibers have low insertion power
loss


Original spectrometer used costs 30K


Spectrometer built with AOTF will be
low cost ($100), compact and
portable


Common Applications




detect chemical compounds



particle sizes



Vibration



acoustic waves


electric field


fluid flow and temperature


Spectrometric Applications



Broadband Infrared (BBIR)



Tunable Camera Filter (TCF)



Portable Optical Spectra
Analyzer (POSA)

The Design of the

Spectrometer


Microcontroller

VCO

Light
Source

AOTF

Photodetector (PD)

Current

to
-

Voltage
Conversion

Output Data

RF
Amplifier

Schematic: Microcontroller
Connection with VCO

1V

2V

3V

4V

2. Press
button again

1. Press
button once

Schematic: Current to Voltage
Converter

Schematic: Overall Circuit




Final Circuit

VCO

C
-
V converter

MCU


Problems

and Solutions


VCO purchased (part
#SN54LS624) did
not output a clean
sinusoidal.


A different VCO was
used (MAX038)



When MAX038 was
connected to
microcontroller, the
VCO gets hot





Results/Conclusion


Successfully controlled VCO


Need to work on why VCO
gets hot.


Controlled C
-
V converter


Could not view output data



Acknowledgements


Said M. Shokair


Dr. Henry P. Lee


Fares Alhassen


Patrick Chan


Kevin Edmonds




UROP


UCI


IM
-
SURE






ANY



QUESIONS?