CONTEXT

A bolometer usually includes a variable resistance depending on the temperature and a body absorbing the incident radiation or another external signal. The extent of the change in this resistance allows a measure of this temperature, allowing itself back to the variation of the incident external signal. The operation principle of bolometer is based on relatively slow thermal phenomena, even if it’s envisaged the miniaturization that allows reducing the time constants. The Performance improvement of the bolometers is a key point to increase the sensitivity and the response time of the targeted applications.

TECHNICAL DESCRIPTION

The invention relates to a bias heating cancellation technique through a high-frequency signal on a bolometer in order to have a better sensitivity, a better dynamics and a more low response time. It’s a new configuration for electrical substitution for bolometers. It’s directly applied to the sensing resistor itself through capacitive coupling. The capacitive coupling allows the independent setting of the electrical and thermal working points.

DEVELOPMENT STAGE

Partnerships with laboratories from Japan and the Unites States were established to demonstrate the performance of this new Bolometer on existing platforms. This work demonstrated that the new Bolometer can be easily configured for different sensors (See Related publications). Therefore this invention can be used for wild range applications.
To summarise the development stage of this invention we can provide:

• Demonstrators
• Results of the related performance
• Some applications

BENEFITS

Performance improvement loop system maintaining a strong capacity for integration. That is to say: improving performance with cost reduction of the sensor.

• unique resistance
• reduction of the bolometer response time
• reliability over time of the bolometers
• the entire conservation of the bolometers
• possibility of the signal-to-noise ratio reduction
• cost reduction

INDUSTRIAL APPLICATIONS

This invention could be used for all applications of electrical substitution of heat technics. Main field application is for room temperature bolometer. An application type in this area is the infrared thermography for night vision devices or augmented-vision device. The invention finds application in civil and military areas.

RELATED PUBLICATIONS (AVAILABLE ON DEMANDE)

Using this invention, several papers were published. Please don’t hesitate to contact for more information or clarifications.
Journal paper
M. Denoual, D. Brouard, A. Veith, O. de Sagazan, M. Pouliquen,  P. Attia, E. Lebrasseur, Y. Mita, G. Allègre, « A heat balanced sigma delta uncooled bolometer », Measurement Science and Technology, Vol. 25, 065101, 2014
M. Denoual, D. Brouard, A. Veith, M. Pouliquen, O. de Sagazan, P. Attia, G. Allègre, « Design of a Sigma-Delta Interface for Heat Balanced Bolometer », Sensors & Transducers, Vol. 18, pp. 33-46, 2013
M. Denoual, S. Lebargy, G. Allègre, « Digital implementation of the capacitively coupled electrical substitution for resistive bolometers », Meas. Sci. Technol., Vol 21, 015205, 2010
M. Denoual , G. Allègre, S. Delaunay, D. Robbes, « Capacitively coupled electrical substitution for resistive bolometer enhancement », Meas. Sci. Technol., Vol 20, 015105, 2009

Invited talk

M. Denoual, « Smart Infrared Detector », Solid State Devices and Materials, Japan, 2014

Book chapters

M. Denoual, M. Pouliquen, G. Allègre,  » Capteur infrarouge intelligents  » in  » Traitement du signal « , Lavoisier publisher, doi:10.3166/ts.30.367.400, pp 367-400, 2014
M. Denoual, O. de Sagazan, P. Attia, G. Allègre, Chapter 8:  » Smart Bolometer: Toward Monolithic Bolometer with Smart Functions » in  » Bolometers « , INTECH publisher, A. G. Unil Perera Editor, ISBN: 978-953-51-0235-9, pp 171-196, 2012
M. Denoual, G. Allègre, Chapter 3:  » Operating Uncooled Resistive Bolometers in a Closed-Loop Mode  » in  » Bolometers : Theory, Types and Applications « , NOVA Science publisher, Torrence M. Walcott Editor, ISBN: 978-1-61728-289-8, 2010

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