TMP006 - fresnel to increase range?

Hi Matthew,

Yes, this is possible to do with the TMP006. In order to come up with an initial design for such a lens you must first know the typical distance from the TMP006 to the target object, as well as the typical size (usually the radius if you assume a circular shape) of your target object.

Best regards,

Ian Williams
Linear Applications Engineer
Precision Analog 

Thank you for the reply. 

Given my proposed application scenario of sensing human presence in a room, range would vary - perhaps from several feet to 15-20 feet?   And a rather wide FOV would be needed.  I suppose 'resolution' would be sacrificed with those lens requirements, but that might be acceptable, as long as some discernible thermal difference could be sensed, detected, and processed by software to determine presence of human body heat source. 

Hi Matthew,

I'll check with our lensing expert regarding your requirements. The large variation in distance may be a challenge, as well as the wide FOV - typically the lens will focus the FOV. In any case, I'll let you know what my colleague thinks.

The software end of things is straightforward. You simply need to detect relative changes in temperature, either with a flat threshold or a slope. The optical gain provided by the lens will increase the SNR of the device enough so that the peaks will be quite large when warm objects enter the FOV.

Best regards,

Ian Williams

Hi Matthew,

After consulting with my colleague, our consensus is that for this application to be successful the FOV would need to be focused to a smaller area within the room. Otherwise, the TMP006 would average the temperature of everything inside its field of view, and the human's contribution to the overall room temperature would not be significant enough to detect. 

Does this work for your application? If not, then a small array (4x4 or 8x8) of sensors could be used to construct a thermal image which could then detect a human's presence accurately.

Best regards,

Ian Williams

Focusing to one small area of a room would probably not work for this application.  But the small array does sound interesting.  In that configuration, I assume each individual sensor would be aligned to a portion of the entire desired FOV.... how would that be accomplished?  Would each sensor have to be angled differently?  Or would that be accomplished via optics of a custom Fresnel lens?

Thank you

Thanks for the information so far.   I am eager to hear back on my latest questions...

Thank you

Hi Matthew,

The array implementation is achieved by both designing a specific lens solution as well as deliberate placement of each sensor which makes up a "pixel" of the image. I will send you a friend request so that I can get you in direct contact with our lensing expert for more information.

Best regards,

Ian Williams