1. Electronic Design of an Acousto Optic Tunable All Fiber Spectrometer
Tanuja A. Mouli
Faculty Mentor: Professor Henry P. Lee
Graduate Student: Fares Alhassen

2. The Project: Big Picture
Unknown Wavelength

3. Acousto Optic Tunable Filter (AOTF)
Metal Frame
Optical Fiber
PZT

4. AOTF: The PZT (Piezo Electric Tansducer)
Aluminum cone is attached to PZT disk
When AC voltage is applied, the cone vibrates up and down
CONE AC
PZT

5. The AOTF When PZT vibrates, it creates a micro acoustic waveRF
PZT and horn
(Piezo Electric Transducer)
When PZT vibrates, it creates a micro acoustic wave
Tunable filter is created by changing the frequency of PZT

6. AOTF: Notch Filter Acts to pass wide range of frequencies
While attenuating narrow band of frequencies

7. AOTF
PZT
Aluminum Cone

8. 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

9. Common Applications detect chemical compounds particle sizes Vibration
acoustic waves
electric field
fluid flow and temperature

10. Spectrometric Applications
Broadband Infrared (BBIR)
Tunable Camera Filter (TCF)
Portable Optical Spectra Analyzer (POSA)

11. The Design of the Spectrometer
Light Source
AOTF
Photodetector (PD)
RF Amplifier
Current –to- Voltage Conversion
VCO
Microcontroller
Output Data

12. Schematic: Microcontroller Connection with VCO
1. Press button once
2. Press button again 1V 2V 3V 4V

13. Schematic: Current to Voltage Converter

14. Schematic: Overall Circuit

15. Final Circuit
C-V converter
VCO
MCU

16. 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

17. Results/Conclusion Successfully controlled VCO
Need to work on why VCO gets hot.
Controlled C-V converter
Could not view output data

18. Acknowledgements Said M. Shokair UROP Dr. Henry P. Lee UCI
Fares Alhassen
Patrick Chan
Kevin Edmonds
UROP
UCI
IM-SURE

19. ANY
QUESIONS?