MEMS infrared sensor including a plasmonic lens

A portable thermal imaging system includes a portable housing configured to be carried by a user, a bolometer sensor assembly supported by the housing and including an array of thermal sensor elements and at least one plasmonic lens, a memory including program instructions, and a processor operably connected to the memory and to the sensor, and configured to execute the program instructions to obtain signals from each of a selected set of thermal sensor elements of the array of thermal sensor elements, assign each of the obtained signals with a respective color data associated with a temperature of a sensed object, and render the color data.

FIELD

This disclosure relates generally to semiconductor sensor devices and methods of fabricating such devices.

BACKGROUND

Infrared radiation (IR) sensors are used in a variety of applications to detect infrared radiation and to provide an electrical output that is a measure of the infrared radiation incident thereon. IR sensors typically use either photonic detectors or thermal detectors for detecting the infrared radiation. Photonic detectors detect incident photons by using the energy of the photons to excite charge carriers in a material. The excitation of the material is then detected electronically. Thermal detectors also detect photons. Thermal detectors, however, use the energy of the photons to increase the temperature of a component. By measuring the change in temperature, the intensity of the photons producing the change in temperature can be determined.

Photonic detectors typically have higher sensitivity and faster response times than thermal detectors. However, photonic detectors must be cryogenically cooled in order to minimize thermal interference, thus increasing the cost, complexity, weight, and power consumption of the device. In contrast, thermal detectors operate at room temperature, thus avoiding the cooling required by photonic detector devices. As a result, thermal detector devices can typically have smaller sizes, lower costs, and lower power consumption than photonic detector devices.

One type of infrared thermal detector is a bolometer device. A bolometer device includes an absorber element for absorbing infrared radiation, a transducer element that has an electrical resistance that varies with temperature, and a substrate. In use, infrared radiation incident upon the bolometer device is absorbed by the absorber element, and the heat generated by the absorbed radiation is transferred to the transducer element. As the transducer element heats in response to the absorbed radiation, the electrical resistance of the transducer element changes in a predetermined manner. By detecting changes in the electrical resistance, a measure of the incident infrared radiation can be obtained.

Bolometer devices must first absorb incident infrared radiation to induce a change in temperature. Typically, however, infrared radiation is dispersed on the absorber as well as portions of the bolometer device that are not configured to absorb infrared radiation, such as the substrate. Accordingly, the efficiency of the bolometer device is less than 100% since the absorber is exposed to only a portion of the incident infrared radiation.

It would be desirable to focus the infrared radiation onto the absorber using a focusing device. Known devices for focusing infrared radiation, however, are very expensive and are typically made using germanium. Furthermore, the cost of known focusing devices for infrared radiation typically exceeds the cost of the bolometer by at least an order of magnitude. Accordingly, while known bolometer devices are effective, there is a constant need to increase the efficiency of bolometer devices, simplify the fabrication, and/or to decrease the production cost of such devices.

SUMMARY

According to an exemplary embodiment of the disclosure, a semiconductor device includes a substrate, a cap wafer, an absorber, and a lens layer. The substrate defines an upper surface. The cap wafer is supported by the substrate and includes a cap layer spaced apart from the substrate. The absorber extends from the upper surface and is located between the substrate and the cap layer. The lens layer is supported by the cap layer. The lens layer defines a plurality of grooves and an opening located over the absorber.

According to another exemplary embodiment of the disclosure, a method of fabricating a semiconductor device includes forming an absorber on a substrate, and supporting a cap layer over the substrate to define a cavity between the substrate and the cap layer in which the absorber is located. The method further includes forming a lens layer on the cap layer. The lens layer is spaced apart from the cavity and defines a plurality of grooves and an opening located over the absorber.

A portable thermal imaging system in a further embodiment includes a portable housing configured to be carried by a user, a bolometer sensor assembly supported by the housing and including an array of thermal sensor elements and at least one plasmonic lens, a memory including program instructions, and a processor operably connected to the memory and to the sensor, and configured to execute the program instructions to obtain signals from each of a selected set of thermal sensor elements of the array of thermal sensor elements, assign each of the obtained signals with a respective color data associated with a temperature of a sensed object, and render the color data.

A method of operating a portable thermal imaging system includes providing a portable housing configured to be carried by a user, supporting a bolometer sensor assembly with the housing, the bolometer sensor assembly including an array of thermal sensor elements and at least one plasmonic lens, obtaining signals from each of a selected set of thermal sensor elements of the array of thermal sensor elements with a processor, assigning each of the obtained signals with a respective color data associated with a temperature of a sensed object, and rendering the color data.

DETAILED DESCRIPTION

As shown inFIG. 1, a prior art micro electromechanical system (MEMS) bolometer pixel10includes an absorber14and two legs18,22. The absorber14is configured to undergo an electrical change in response to absorbing infrared radiation24(shown schematically as a downward pointing arrow and also referred to herein as “radiation” and “IR”). When the absorber14is exposed to the IR24emitted from an object (not shown), the absorber heats up and undergoes, for example, a change in electrical resistance, which is detected using an external electrical circuit (not shown). The exemplary absorber14is shown as being a substantially planar rectangular element. In another embodiment, however, the absorber14has any desired shape and/or configuration.

The legs18,22extend from the absorber14and are configured to be electrically connected to the external electrical circuit that monitors the electrical state of the absorber14. In one embodiment, the external circuit is configured to generate an output that represents a temperature based on an electrical resistance of the absorber14, as measured from the leg18to the leg22.

The bolometer pixel10, including the absorber14and the legs18,22, is typically formed from an ultra-thin layer (approximately 10 nm), of metal. Exemplary metals include, but are not limited to, vanadium oxide, platinum, and titanium. In another embodiment, the bolometer pixel10is formed from any desired material.

As shown inFIG. 2, a plurality of the bolometer pixels10is arranged in a focal plane array on a substrate28. The substrate28is substantially planar and is also referred to herein as a “reflector” and a “reflector layer.” The substrate28is typically formed from silicon using CMOS technology, but may be formed/made using any desired material and technology.

FIG. 3shows a typical prior art bolometer sensor assembly34that includes the substrate28, the plurality of bolometer pixels10, and a cap wafer38. The cap wafer38extends from the substrate28and defines a cap layer42that is spaced apart from the bolometer pixels10by a distance46. In one embodiment, the cap wafer38is formed from undoped or lowly doped silicon; however, the cap wafer may be formed from any desired material that is at least partially transparent to the IR24.

The bolometer sensor assembly34is shown inFIG. 3as being exposed to infrared radiation24that is emitted by an object (not shown). The cap wafer38passes most of the IR24through to the pixels10. Specifically, the material of the cap wafer38transmits about 60% to 70% of the IR24through the cap layer42. When the IR24passes through the cap wafer38it is dispersed across the pixels10and the substrate28. The percentage of the IR24that is incident on portions of the bolometer sensor assembly34other than the bolometer pixels10is generally not used to determine the temperature of the object. This leads to an inherent inefficiency of the prior art bolometer sensor assembly34, since only a portion of the available IR24is used to heat the bolometer pixels10.

As shown inFIG. 4, a bolometer sensor assembly100, which is a semiconductor sensor device, includes a substrate104, a plurality of bolometer pixels108(only one of which is shown), a cap wafer112, and a lens layer114. Infrared radiation (IR)120is shown as being incident on the bolometer sensor assembly100. The lens layer114includes a plurality of plasmonic lens structures116(only one of which is shown) that are configured to focus/beam the IR120into an IR ray124that is incident directly onto the pixel108, thereby significantly increasing the efficiency of the bolometer sensor assembly100.

The substrate104is substantially planar and is also referred to herein as a “reflector” or a “reflector layer.” The substrate104is typically formed from silicon using CMOS technology, but may be formed/made using any desired material and technology including silicon on insulator (SOI) technology.

The bolometer pixel108, which is also referred to herein as an “absorber,” is substantially identical to the bolometer pixel10ofFIG. 1. In another embodiment, the bolometer pixel108is provided as any type of bolometer pixel as desired. The bolometer pixel108extends from an upper surface128of the substrate104.

The cap wafer112is supported by the substrate104and includes a support structure132and a cap layer136. The support structure132extends upward from the upper surface128of the substrate104. The cap layer136extends from the support structure136and is spaced apart from the substrate104by a distance140, such that a cavity138is defined between the upper surface128of the substrate and a lower surface142of the cap layer136. The bolometer pixel108is located between the substrate104and the cap layer136and is at least partially located in the cavity138. The cap layer136is substantially parallel to the substrate104.

In one embodiment, the cap wafer112is formed from undoped or lowly doped silicon; however, the cap wafer may be formed from any desired material that is at least partially transparent to the IR120. Furthermore, in some embodiments, the support structure132and the cap layer136are formed from different materials.

A post148and a plurality of ridges152are formed on an upper surface144of the cap layer136. The post148, which is also referred to herein as pillar, is a substantially cylindrical protuberance that extends upward (as shown inFIG. 4), away from the upper surface144of the cap layer136for a post distance156. An exemplary post distance156is approximately 2.5 micrometers (2.5 μm). The post148defines a diameter of approximately 400 nanometers (400 nm). In another embodiment, the post148is any desired size and shape, such as square, rectangular, triangular, or any other desired shape including irregular shapes.

With additional reference toFIG. 5, the ridges152are substantially circular and are concentrically arranged on the upper surface144of the cap layer136. The ridges152, as well as the bolometer pixel108, are shown in phantom inFIG. 5since they are located below the lens layer114as viewed from above. The cap layer136includes five of the ridges156, but in other embodiments the cap layer includes any desired number of ridges. Each ridge156extends upward (as shown inFIG. 4), away from the upper surface144of the cap layer136for a ridge distance160that is less than the post distance156. In one exemplary embodiment, the ridge distance160is approximately one micrometer (1 μm). As illustrated, the ridges152are approximately evenly spaced apart from each other, but may be unevenly spaced apart in another embodiment. Furthermore, the ridges152may have any desired shape and configuration including non-concentric configurations.

The lens layer114is supported by the cap layer136and, in particular, is located generally above the upper surface144of the cap layer in the embodiment ofFIG. 4. The lens layer114is referred to as being “generally above” the upper surface144, since the post148may be considered part of the upper surface144and the post extends completely through the lens layer. With such an interpretation, the lens layer114is not “completely” above the upper surface144, but is “generally above” the upper surface. In the illustrated embodiment, the lens layer114is formed on the upper surface144of the cap layer136; however, in other embodiments, one or more other layers (not shown) may be positioned between the upper surface and the lens layer.

The lens layer114defines an upper surface164that is substantially planar and an opposite lower surface176. The upper surface164is spaced apart from the lower surface176by approximately the post distance156. Accordingly, a thickness of the lens layer114is approximately 2.5 micrometers (2.5 μm), in one embodiment.

The lens structure116of the lens layer114includes a plurality of grooves168and an IR opening172. The grooves168are concentric circular grooves that are centered about the IR opening172. The grooves168are defined in the lower surface176and are complementary in shape and size to the ridges152formed in/on the cap layer136, such that the grooves are at least partially filled by the ridges (i.e. the material of the cap wafer112). In one embodiment, the grooves168define a cross sectional area of approximately one square micrometer (1 μm) and are spaced apart from each other by approximately five micrometers (5 μm). The lens structure116includes the same number of grooves168as the number of ridges152. Accordingly, the lens structure116includes five of the grooves168in the exemplary embodiment. The grooves168define a depth178that is less than the thickness of the lens layer114.

With continued reference toFIG. 4, the IR opening172, which is also referred to herein as an opening, a circular opening, an aperture opening, and an aperture, extends completely through the thickness of the lens layer114, unlike the grooves168. The IR opening172is positioned at approximately the center of each of the grooves168, as shown inFIG. 5, and is located over the bolometer pixel108. The IR opening172is complementary in shape and size to the post148and is substantially/completely filled with the post. The IR opening172and the post148are configured to be exposed to the IR120. Depending on the configuration of the lens structure116, the IR opening172may pass electromagnetic radiation outside of the infrared range.

The lens layer114may be formed from a “perfectly conducting material” (PCM) that is configured to prevent the passage of IR therethrough. The PCM has zero electrical resistance (i.e. is a perfect conductor) and is configured to block 100% of the IR120incident thereon. Accordingly, suitable materials for forming the lens layer114include metal, such as platinum, metallic alloys, and the like.

As shown inFIG. 6, a method of fabricating the bolometer sensor assembly100includes providing the substrate104. Next, the bolometer pixel108is formed on the upper surface128of the substrate104according to any desired process. After formation of the bolometer pixel108, the cap wafer112is applied/formed on the substrate104using any process.

Next, with reference toFIG. 7, a first portion of a sacrificial layer180is deposited on the upper surface144of the cap layer136. The sacrificial layer180defines a thickness approximately equal to the ridge distance160(FIG. 4). The sacrificial layer180is formed from any suitable material.

The method further includes applying/depositing/forming/printing a mask (not shown) on the sacrificial layer180. The mask is a resist mask, a photo mask, or the like. The mask is applied in a pattern that corresponds to the desired configuration of the ridges152, but does not typically account for the post148(in this exemplary embodiment). The sacrificial layer180is trenched through the mask to form a plurality of concentric grooves184. The grooves184are complimentary in size and shape to the ridges152.

As shown inFIG. 8, next the material of the cap wafer112is deposited into the grooves184to form the ridges152. After the depositing, the ridges152and the sacrificial layer180may be polished using chemical and mechanical polishing (CMP) or any other desired smoothing/polishing process.

With reference toFIG. 9, a second portion of the sacrificial layer180is formed over the ridges152. Then, another mask (not shown) is applied to the sacrificial layer180in a pattern that corresponds to the desired configuration of the post148. Afterwards, the sacrificial layer180is trenched to form a post opening188that extends through the sacrificial layer.

InFIG. 10, material of the cap wafer112is deposited into the post opening188to form the post148. Next, as shown inFIG. 11, the sacrificial layer180is etched away, using any desired process. Removal of the sacrificial layer180exposes the post148, the ridges152, and the upper surface144of the cap layer136.

According toFIG. 12, a conformal layer192of the material of the lens layer114(FIG. 4) is deposited onto the upper surface144of the cap layer136, the post148, and the ridges152. In the illustrated embodiment, the conformal layer192is formed using a predetermined number of cycles of atomic layer deposition (ALD). The conformal layer192includes a plurality of curved surfaces196and valleys200. The valleys200correspond approximately to a midpoint between the ridges152. An apex of the curved surfaces196corresponds to the location of the ridges152. The valleys200and the curved surfaces196are a consequence of the layered formation of the conformal layer192. In another embodiment the material of the lens structure116is deposited using any desired process including sputtering and evaporative techniques.

Next, with further reference toFIG. 4, the conformal layer192is smoothed using CMP or another desired process to arrive at the smooth and flat upper surface164of the lens structure116. The polishing step removes a portion of the conformal layer192that is in contact with a post upper surface204, thereby uncapping the IR opening172. After polishing, the ridges152, however, remain buried below the upper surface164of the lens layer114and are not directly exposed to the IR120.

In operation, the lens structure116focuses and/or to beams the IR120into an IR ray124that is directed onto an absorber (see, e.g., absorber14,FIG. 1) of the bolometer pixel108. With continued reference toFIG. 4, when the lens layer114is exposed to the IR120, the lens structure116enables the IR to pass through the IR opening172, but blocks the passage of the IR through all other areas of the lens layer114. As a result of the size and shape of the grooves168(among other factors), the IR120that passes through the IR opening172is emitted as the focused ray of IR124. The IR ray124passes through the cap layer136and is incident on the pixel108. Accordingly, the lens structure116functions as a plasmonic lens that is configured to focus the IR120onto the pixel108instead of allowing the IR to be scattered across the substrate104as in the prior art bolometer sensor assembly34ofFIG. 3. Additionally, the lens structure116results in more efficient absorption of the IR120by the pixel108and a higher responsively from the sensor device100.

The lens structure116is configurable to pass a particular wavelength of electromagnetic radiation therethrough, typically in the infrared range. In particular, the wavelength of electromagnetic radiation that passes through the IR opening172is dependent on the shape of the opening172, the diameter of the opening172, the number of the grooves168, and the size of the grooves168(width and depth), among other factors. In general, the efficiency of the lens structure116increases as the incoming electromagnetic radiation approximates the target wavelength of the lens. In this way, the lens structure116is configurable to be sensitive to a particular wavelength or a range of wavelengths, instead of being sensitive to all wavelengths of electromagnetic radiation in general. In one embodiment, the bolometer sensor assembly100includes a lens layer114having a plurality of differently configured lens structures116to enable the semiconductor device to be sensitive to more than one desired wavelength or more than one range of wavelengths.

As shown inFIGS. 13 and 14, another embodiment of a bolometer sensor assembly300includes a substrate304, a plurality of bolometer pixels308(only one of which is shown), a cap wafer312, and a plurality of lens structures316(only one of which is shown) formed in a lens layer314. A post348and a plurality of ridges352and are formed on an upper surface344of a cap layer336of the cap wafer312. The lens structure316defines an aperture372in which the post348is located, and a plurality of grooves368that is substantially/completely filled with the ridges352.

The bolometer sensor assembly300is substantially identical to the bolometer sensor assembly100, except that the post348and the ridges352are formed from a material that is different than the material of the cap wafer312. The material of the post348and the ridges352is deposited into trenches formed in a sacrificial layer (See e.g. grooves184formed in the sacrificial layer180ofFIG. 8) using any commonly used deposition technique including evaporation, sputtering, and ALD among others.

The post348and the ridges352may be formed from a material having a refractive index that is close to the refractive index of air. The wavelength of the electromagnetic radiation (typically IR) that the lens structure316is configured to efficiently focus through the aperture372is based on the material from which the post348and the ridges352is formed. Accordingly, by selecting a material with a particular index of refraction the lens structure316is “tuned” to a desired wavelength of electromagnetic radiation.

As shown inFIGS. 15 and 16, another embodiment of a bolometer sensor assembly400includes a substrate404, a plurality of bolometer pixels408(only one of which is shown), a cap wafer412, and a plurality of lens structures416(only one of which is shown). The lens structure416defines an aperture472and a plurality of grooves468.

The bolometer sensor assembly400is substantially identical to the bolometer sensor assembly100, except that the bolometer sensor assembly400does not include a post148or the ridges152. Instead, the grooves468and the aperture472are gas-filled/air-filled voids. The type of gas(es) in the gas-filled468,472voids is selectable to have a desired index of refraction to enable “tuning” of the lens structure416.

In one embodiment, the grooves468and the aperture472of the bolometer sensor assembly400are formed similarly to the grooves168and the IR opening172of the semiconductor device100. Instead of forming the post148and the ridges152from the material of cap wafer112, however, the post148and the ridges152are formed form a thermally decomposable sacrificial polymer such as “Unity” or a photo-definable material. The thermally decomposable material of the post148and the ridges152is deposited using any commonly used deposition technique including evaporation, sputtering, and atomic layer deposition among others. A thermally decomposable sacrificial polymer is a material that is selectively removable from the bolometer sensor assembly100in response to being heated to a predetermined temperature. The bolometer sensor assembly400is heated to approximately300to400degrees Celsius, for example, in order to evaporate/decompose the thermally decomposable sacrificial polymer. Upon being heated, the thermally decomposable sacrificial polymer evaporates through the material of the lens structure416and/or through the material of the cap wafer412. Evaporation of the material of the post148and the ridges152leaves behind the air-filled grooves468and the aperture472.

As shown inFIGS. 17 and 18, another embodiment of a bolometer sensor assembly500includes a substrate504, a plurality of bolometer pixels508(only three of which are shown), a cap wafer512, and lens layer514includes a plurality of lens structures516(only one of which is shown). An aperture ridge548and a plurality of ridges552and are formed on an upper surface544of a cap layer536of the cap wafer512. The lens structure defines a slit572(also referred to herein as an opening, an aperture opening, and an aperture) in which the aperture ridge548is located, and a plurality of grooves568that is substantially/completely filled with the ridges552.

The bolometer sensor assembly500is substantially identical to the bolometer sensor assembly100, except that the grooves568and the aperture572are substantially linear and extend in a slit direction590instead of being circular. The lens structure516functions substantially similarly as the lens structure116to focus/beam the IR (see IR120ofFIG. 4) onto the bolometer pixels508.

As shown inFIGS. 19 and 20, another embodiment of a bolometer sensor assembly600includes a substrate604, a plurality of bolometer pixels608(only three of which are shown), a cap wafer612, and a lens layer614defining a plurality of lens structures616(only six of which are shown). Each of the lens structures616defines an aperture672and a plurality of grooves668.

The bolometer sensor assembly600is substantially identical to the bolometer sensor assembly400, except that the lens layer614(and the lens structures616formed thereon) is located in a cavity638defined between the substrate604and a cap layer636of the cap wafer612. Since the lens structures616are positioned on an “underside” of the cap layer636the IR (see IR120ofFIG. 4) passes through the cap layer before being focused by the lens structures616.

As shown inFIGS. 21 and 22, another embodiment of a bolometer sensor assembly700includes a substrate704, a plurality of bolometer pixels708(only three of which are shown), a cap wafer712, and a lens layer714defining a plurality of lens structures716(only three of which are shown). Each of the lens structures716defines a slit-shaped aperture772and a plurality of substantially linear grooves768.

The bolometer sensor assembly700is substantially identical to the bolometer sensor assembly500, except that the lens structures716are located between the substrate704and a cap layer736of the cap wafer712. Since the lens structures716are positioned on an “underside” of the cap layer736the IR (see IR120ofFIG. 4) passes through the cap layer before being focused by the lens structures716.

While many of the embodiments discussed above depicted and made reference to only one pixel, the single pixel in various embodiments is replaced by an array of pixels. For example, each of the pixel108, the pixel308, and the pixel408, in various embodiments, is provided as an array of pixels. Such an array is provided in some embodiments in a portable device such as the portable device ofFIGS. 23 and 24, generally designated800, which in this embodiment is a cellular telephone. In some embodiments, the portable device is a personal digital assistant, a smart phone, a dedicated sensor device, or other desired portable device. The portable device800has a housing802that includes an upper housing portion804and a lower housing portion806. An inner display808is located on the inner side of the upper housing portion804and an outer display810is located on the outer side of the upper housing portion804as depicted inFIG. 24. The outer side of the upper housing portion804further includes a thermal sensor assembly port812, a camera port814and a light port816.

Referring again toFIG. 23, the lower housing portion806includes a keyboard818and a microphone port820. A data port822and a charging port824are located on the side of the lower housing portion806.

FIG. 25depicts a control circuit830which is located within the housing802. The control circuit830includes a processor832and a memory834which in this embodiment are located within the lower housing portion806. The processor832is operably connected to the keyboard818and the data port822. The processor832is further operably connected to a power source836which is accessed through the charging port824and a microphone838positioned adjacent to the microphone port820.

The processor832is also operably connected to components in the upper housing portion804including the inner display808and the outer display810. The processor832is further operably connected to a bolometer sensor assembly840, a charge coupling device (CCD)842and a light844which are physically located adjacent to the sensor assembly port812and are part of an imaging subsystem, the camera port814and the light port816, respectively.

The bolometer sensor assembly840is shown in further detail inFIG. 26. The bolometer sensor assembly840includes a substrate850and an array852of thermal sensors8541-5. The array852is located within a chamber856defined in part by a cap858. A plasmonic lens860is connected to the underside of the cap858. In various embodiments, the location and configuration is provided in the manner described above for the lenses116,316,416,516, and716. In the embodiment ofFIG. 26, the plasmonic lens860includes one lens structure which is substantially identical to the plasmonic lens structures616ofFIG. 19, and focuses and/or beams IR incident on the cap858, much like an optical lens focuses and/or beams electromagnetic radiation in the visible spectrum. The plasmonic lens860is made of a “perfectly conducting layer”, such as any type of metal, for example.

Like the lenses616, the plasmonic lens860includes a number of concentric grooves862and a central aperture864. The plasmonic lens860includes in various embodiments from about five up to about 50 concentric grooves862, which may also be referred to as surface corrugations. The central aperture864is generally circular and extends completely through the plasmonic lens860.

The plasmonic lens860is connected to the cap wafer858with the grooves862facing away (i.e. spaced apart from) from the cap wafer. The cap wafer858, which is imperforate in this embodiments, does not include an opening aligned with the aperture864. Accordingly, visible light does not pass through the cap wafer858; however, as described above, most of the IR passes through the cap wafer.

Returning toFIG. 25, within the memory834are stored program instructions870. The program instructions870, which are described more fully below, are executable by the processor832and/or any other components as appropriate. The program instructions870include commands which, when executed by the processor832, cause the portable device800to obtain data for use in determining the temperature of an object within a field of view of the sensor assembly840.

Referring toFIG. 27, there is depicted a flowchart or a process, generally designated874, setting forth an exemplary manner of obtaining data for use in obtaining a thermal image and/or determining the temperature of an object within a field of view of the sensor assembly840by executing the program instructions870according to the present principles. Initially, a user carrying the portable device800opens the housing802to the position shown inFIG. 23and uses the keyboard818to place the portable device800in temperature imaging mode (block876). In embodiments which are configured solely for temperature detection, solely for thermal imaging, or for both thermal detection and imaging, the device may only need to be energized. In embodiments such as the portable device800, the display808in some embodiments is configured to render a menu which the user uses to activate the temperature detection mode.

Once the portable device800is placed in temperature detection mode, the processor832controls the CCD842to an energized condition (block878). In response, the CCD842begins to detect incoming energy in any acceptable manner and generates a signal indicative of the sensed energy. The processor832receives the generated signal and controls the inner display808to render the scene viewed (sensed) by the CCD842(block880).

Using the rendered image as a guide, the user frames the desired scene/object (block882). Framing of the object in some embodiments is accomplished by zooming the display such that the object fills the display808. In other embodiments, a shadow frame overlying the viewed scene is manipulated to frame the object. As the object is framed using the inner display808, the processor832in some embodiments selects a subset of the thermal sensors8541-5in the array852. By varying the number of active pixels (each of the thermal sensors8541-5is a separate pixel), the field of view (FOV) of the sensor assembly840is adjusted to comport with the framing of the object in the display808(block884). Once the object is framed, the user initiates thermal data acquisition (block886) such as by pressing a key in the keyboard818. In response, the processor832controls the array852to generate a respective signal from each of the selected thermal sensors1541-5(block888).

In some embodiments, the CCD842is omitted or not used and the array852is used to provide an image. In such embodiments, blocks878-882are omitted and the processor832or an ASIC included with the device, is configured to generate data that forms an output thermal image. In either embodiment, the ASIC or processor832is configured to process the electrical signal(s) generated by each of the bolometer pixels854. In particular, based on the resistance of the bolometer pixels854, the processor832generates data that corresponds to thermal information contained in the focused ray.

Each IR data point is then assigned a color in the visual spectrum based on the intensity of the IR sensed by the corresponding bolometer pixel854(or group of bolometer pixels) (block890). Typically, “high” intensities of IR receive a light color such as white and “low” intensities of IR receive a dark color such as blue or black. Additionally, each IR data point is assigned a temperature value, which is also based on the intensity of the IR sensed by the corresponding bolometer pixel854(or group of bolometer pixels). The visual spectrum data is then rendered (block892).

By way of example,FIG. 28depicts an exemplary image900from the CCD842rendered on the display808at block880. In the image900, an individual902and a bag904are visible.FIG. 29depicts an exemplary image910from the array852of the same individual902rendered on the display808at block892. As shown inFIG. 29, the output thermal image910shows the hands912of the individual902which are not detectable by the CCD842. In the embodiment ofFIG. 29, the display808is a touchscreen. Consequently, when a user touches the touchscreen display808, the processor832receives touch input from the display808and causes the temperature data associated with the color data which is rendered at a location of the display which was touched to be displayed. Consequently, the temperature data associated with that region of the output thermal image910which is touched is displayed (block894). Accordingly, the user is able to determine the temperature of a particular portion the image900or the image910by simply touching the corresponding region of the output thermal image910on the touchscreen display808.

In one embodiment, the array852includes approximately one thousand bolometer pixels854positioned on the substrate layer850and arranged in a focal plane array (“FPA”). For clarity of viewing, however, only five bolometer pixels854are illustrated inFIG. 26. In another embodiment, the array852includes between 500 and 100,000 of the bolometer pixels854.

The bolometer pixels854are arranged on the substrate layer850in a position to receive a focused ray from the lens860. In one embodiment, the pixels854are arranged in a generally rectangular shaped array. In another embodiment, the bolometer pixels854are arranged in a differently shaped array, such as an array having a shape that matches (at least approximately) the shape of a focused ray incident on the substrate layer850. Furthermore, the bolometer pixels854may be arranged in an array having any other shape as desired by those of ordinary skill in the art. Additionally, the bolometer pixels are arranged according to a Cartesian coordinate system, such that each bolometer pixel854in the focal plane array has a unique address on the substrate layer850. In another embodiment, the bolometer pixels854are arranged according to any other coordinate system that enables each bolometer pixel to have a unique address on the substrate layer850.