A novel acousto-optic tunable filter for use in hyperspectral imaging systems

C. Stedham; M. Draper; J. Ward; E. Wachman; C. Pannell

doi:10.1117/12.765532

22 February 2008 A novel acousto-optic tunable filter for use in hyperspectral imaging systems

C. Stedham, M. Draper, J. Ward, E. Wachman, C. Pannell

Proceedings Volume 6889, Physics and Simulation of Optoelectronic Devices XVI; 68891C (2008) https://doi.org/10.1117/12.765532
Event: Integrated Optoelectronic Devices 2008, 2008, San Jose, California, United States

Abstract

The design and performance characteristics of a novel Acousto Optic Tunable Filter (AOTF) are presented. Particular attention has been paid to the reduction of optical side lobes, maximising the light throughput and achieving efficient wideband RF matching of a device for use in hyperspectral imaging systems. Conventional AOTFs are known to yield an optical pass band with side lobes at unacceptable levels of ~-10dB relative to the transmission peak. It is known that shaping the acoustic beam ("apodisation") can suppress the side lobe transmission of the AOTF and improve its imaging capabilities. Results of a novel electrode apodisation pattern are presented, reducing sidelobes to ~-25dB. This produces an AOTF which is capable of being placed in a diffraction limited optical system and introduces negligible amounts of image degradation. The large transducer area (associated with the large optical aperture) and acoustic impedance mismatch between the AO substrate (TeO₂) and transducer (LiNbO₃) pose a challenge in achieving wideband RF performance. Acoustic mismatch between substrate and transducer has been addressed by the introduction of a special acoustic matching layer in the bond. The layer reduces dispersion in the transducer impedance easing broadband matching. The transducer has a low (<1 Ohm) radiation resistance which must be matched to the RF driver (typically 50 ohms). This very low impedance may be swamped by the parasitic impedances of the electrode, bond layers and wire bonds used for electrical connection. Thus, the transducer is split into series-connected sections to increase the "bare" impedance. We present results to show the performance increase that can be obtained this way.

Citation Download Citation

C. Stedham, M. Draper, J. Ward, E. Wachman, and C. Pannell "A novel acousto-optic tunable filter for use in hyperspectral imaging systems", Proc. SPIE 6889, Physics and Simulation of Optoelectronic Devices XVI, 68891C (22 February 2008); https://doi.org/10.1117/12.765532

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available