Abstract
An uncooled infrared (IR) imaging system that is based on thermomechanical sensing of IR radiation in conjunction with a visible optical readout has been developed. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams made of silicon nitride (SiN x) and gold (Au) in each pixel. Absorption of incident IR radiation in the 8-14 μm wavelength range by SiN x in each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. The FPA design involved maximizing the thermal resistance between the pixel and its surroundings, maximizing the thermomechanical response within the constraints of the pixel size, optimizing the pixel time response, and maximizing the IR absorption using thin film optics. Microfabrication of stress-balanced bimaterial cantilevers was achieved by varying the silicon concentration along the thickness of the SiN x films in order to balance the residual tensile stress in the Au film and the Cr adhesion layer between Au and SiN x. The optical readout utilized Fourier diffractive optics to simultaneously detect deflections of all cantilevers using a single light source. The results suggest that objects at temperatures as low as 30 °C can be imaged with the best noise-equivalent temperature difference (NETD) in the range of 2-5 K. It is estimated that further improvements that are currently being pursued can improve NETD below 5 mK.
| Original language | English |
|---|---|
| Title of host publication | Proceedings of SPIE - The International Society for Optical Engineering |
| Publisher | Society of Photo-Optical Instrumentation Engineers |
| Pages | 74-79 |
| Number of pages | 6 |
| Volume | 3948 |
| Publication status | Published - 2000 |
| Externally published | Yes |
| Event | Photodetectors: Materials and Devices V - San Jose, CA, USA Duration: 2000 Jan 25 → 2000 Jan 28 |
Other
| Other | Photodetectors: Materials and Devices V |
|---|---|
| City | San Jose, CA, USA |
| Period | 00/1/25 → 00/1/28 |
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ASJC Scopus subject areas
- Electrical and Electronic Engineering
- Condensed Matter Physics
Cite this
Infrared vision using uncooled optomechanical camera. / Majumdar, A.; Mao, M.; Perazzo, T.; Zhao, Y.; Kwon, Oh Myoung; Varesi, J.; Norton, P.
Proceedings of SPIE - The International Society for Optical Engineering. Vol. 3948 Society of Photo-Optical Instrumentation Engineers, 2000. p. 74-79.Research output: Chapter in Book/Report/Conference proceeding › Conference contribution
}
TY - GEN
T1 - Infrared vision using uncooled optomechanical camera
AU - Majumdar, A.
AU - Mao, M.
AU - Perazzo, T.
AU - Zhao, Y.
AU - Kwon, Oh Myoung
AU - Varesi, J.
AU - Norton, P.
PY - 2000
Y1 - 2000
N2 - An uncooled infrared (IR) imaging system that is based on thermomechanical sensing of IR radiation in conjunction with a visible optical readout has been developed. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams made of silicon nitride (SiN x) and gold (Au) in each pixel. Absorption of incident IR radiation in the 8-14 μm wavelength range by SiN x in each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. The FPA design involved maximizing the thermal resistance between the pixel and its surroundings, maximizing the thermomechanical response within the constraints of the pixel size, optimizing the pixel time response, and maximizing the IR absorption using thin film optics. Microfabrication of stress-balanced bimaterial cantilevers was achieved by varying the silicon concentration along the thickness of the SiN x films in order to balance the residual tensile stress in the Au film and the Cr adhesion layer between Au and SiN x. The optical readout utilized Fourier diffractive optics to simultaneously detect deflections of all cantilevers using a single light source. The results suggest that objects at temperatures as low as 30 °C can be imaged with the best noise-equivalent temperature difference (NETD) in the range of 2-5 K. It is estimated that further improvements that are currently being pursued can improve NETD below 5 mK.
AB - An uncooled infrared (IR) imaging system that is based on thermomechanical sensing of IR radiation in conjunction with a visible optical readout has been developed. The system contains a focal plane array (FPA) consisting of bimaterial cantilever beams made of silicon nitride (SiN x) and gold (Au) in each pixel. Absorption of incident IR radiation in the 8-14 μm wavelength range by SiN x in each cantilever beam raises its temperature, resulting in proportional deflection due to mismatch in thermal expansion of the two cantilever materials. The FPA design involved maximizing the thermal resistance between the pixel and its surroundings, maximizing the thermomechanical response within the constraints of the pixel size, optimizing the pixel time response, and maximizing the IR absorption using thin film optics. Microfabrication of stress-balanced bimaterial cantilevers was achieved by varying the silicon concentration along the thickness of the SiN x films in order to balance the residual tensile stress in the Au film and the Cr adhesion layer between Au and SiN x. The optical readout utilized Fourier diffractive optics to simultaneously detect deflections of all cantilevers using a single light source. The results suggest that objects at temperatures as low as 30 °C can be imaged with the best noise-equivalent temperature difference (NETD) in the range of 2-5 K. It is estimated that further improvements that are currently being pursued can improve NETD below 5 mK.
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M3 - Conference contribution
VL - 3948
SP - 74
EP - 79
BT - Proceedings of SPIE - The International Society for Optical Engineering
PB - Society of Photo-Optical Instrumentation Engineers
ER -