METHOD AND DEVICE FOR ACCESS CONTROL OF PERSONS BASED ON A TEMPERATURE MEASUREMENT

Abstract

A method and device are provided access control of persons. The method includes: detecting by sensor a reference radiation in the infrared, IR, wavelength range using an IR image sensor; and calibrating the IR image sensor as a temperature sensor in relation to the acquired reference radiation used as a standard at the reference temperature. The method also includes acquiring by image sensor at least an area section of a body surface of a person to be controlled and generating thermal image data representing the thermal image of the area section acquired; determining a body temperature of the person; and allowing or denying access of the person to an access-restricted spatial area based on the determined body temperature.

Claims

1. A method for access control of persons, comprising: detecting by sensor a reference radiation in an infrared, IR, wavelength range, which was emitted by a thermal reference radiation source at a known reference temperature (T.sub.R), using an IR image sensor; calibrating the IR image sensor as a temperature sensor in relation to the detected reference radiation serving as a standard at the reference temperature (T.sub.R); acquiring by image sensor at least an area section of a body surface of a person to be controlled in the infrared wavelength range by of the IR image sensor and generating thermal image data representing a thermal image of the area section acquired; determining a body temperature (T.sub.K) of the person assigned to the area section based on the thermal image data and taking into consideration the calibration; granting or denying access of the person to an access-restricted spatial area in dependence on the determined body temperature.

2. The method of claim 1, further comprising: acquiring by image sensor the at least one area section in the visible wavelength range and generating image data representing the image of the area section acquired; and detecting at least one biometric feature of the person based on the image data; wherein the granting or denying of access for the person to the access-restricted spatial area additionally takes place in dependance on the at least one specific biometric feature.

3. The method of claim 2, further comprising: identifying two or more partial areas in the area section based on the at least one biometric feature as respective images of specific respective body surface sections of the person (P); assigning a respective local body temperature (T.sub.K) of the person to each of these partial areas based on the thermal image data and taking into consideration the calibration; comparing at least two of the respective local body temperatures to one another or to a respective assigned temperature standard for the respective body surface sections; wherein the granting or denying of the access of the person to the access-restricted spatial area additionally takes place in dependence on whether the comparison result(s) meet(s) an access criterion assigned to the comparison(s).

4. The method of claim 1, wherein the body temperature (T.sub.K) of the person assigned to the area section is determined based on the thermal image data and in consideration of the calibration in such a way that only the respective temperature values of one or more partial areas of the area section from the thermal image are selectively used for this purpose, in which the partial areas or their temperature values or both correspond to a predetermined selection criterion.

5. The method of claim 2, further comprising: determining the image area proportion (F) within the image represented by the image data of the total area (A) of the image which images a predetermined selected body surface section of the person; checking whether the image area proportion (F) meets an image area proportion criterion (R) specifying a minimum required image area; and if according to the test the image area proportion (F) does not meet the image area proportion criterion (R), denying the access of the person to the access-restricted spatial area.

6. The method of claim 2, further comprising: correcting the perspective of the image of the surface area represented by the image data before the at least one biometric feature of the person is detected based on the image that is then corrected in perspective.

7. The method of claim 1, wherein in case of a denial of access, one or more of the following reactions is triggered: an audible or visual alarm; physically blocking access to the access-restricted spatial area; sending a signal or message to a predetermined recipient to notify the denial of access; generating a physical access token having an encrypted message to a predetermined recipient notifying that access has been denied.

8. The method of claim 3, wherein the body temperature (T.sub.K) of the person assigned to the area section is determined based on the thermal image data and in consideration of the calibration in such a way that only the respective temperature values of one or more partial areas of the area section from the thermal image are selectively used for this purpose, in which the partial areas or their temperature values or both correspond to a predetermined selection criterion; and the method further comprises: determining the image area proportion (F) within the image represented by the image data of the total area (A) of the image which images a predetermined selected body surface section of the person; checking whether the image area proportion (F) meets an image area proportion criterion (R) specifying a minimum required image area; if according to the test the image area proportion (F) does not meet the image area proportion criterion (R), denying the access of the person to the access-restricted spatial are; correcting the perspective of the image of the surface area represented by the image data before the at least one biometric feature of the person is detected based on the image that is then corrected in perspective, wherein in case of a denial of access, one or more of the following reactions is triggered: an audible or visual alarm; physically blocking access to the access-restricted spatial area; sending a signal or message to a predetermined recipient to notify the denial of access; generating a physical access token having an encrypted message to a predetermined recipient notifying that access has been denied.

9. A device for access control of persons, comprising: an IR image sensor for acquiring by image sensor radiation in an infrared, IR, wavelength range and for generating thermal image data representing a thermal image acquired; a reference radiation source for emitting an at least partially infrared reference radiation at a known reference temperature (T.sub.R) of the reference radiation source provided as a standard for calibrating the IR image sensor as a temperature sensor; an access control device for signaling or effectuating a grant or denial of access of a person to an access-restricted spatial area; and a controller, which is configured: to carry out the calibration of the IR image sensor as a temperature sensor in relation to an acquired reference radiation used as a standard at the reference temperature (T.sub.R); to determine a body temperature (T.sub.K) for an area section of a body surface of the person to be controlled, represented by the thermal image data, taking into consideration the calibration; and to activate the access control device in order to grant or deny the person access to the access-restricted spatial area in dependence on the determined body temperature (T.sub.K).

10. The device of claim 9, further comprising: a VIS image sensor for acquiring by image sensor the at least one area section in the visible wavelength range, VIS, and for generating the Image data representing the image data acquired.

11. The device of claim 9, further comprising: a thermocouple for determining by sensor the reference temperature (T.sub.R) of the reference radiation source.

12. The device of claim 9, wherein the IR image sensor or the VIS image sensor are configured so that their respective position, their orientation, or their focus are variably adjustable in order to be able to vary the image detail that can be acquired by the respective image sensor.

13. The device of claim 9, wherein: the reference radiation source is arranged in the same housing as the IR image sensor; the field of view of the IR image sensor has a partial field of view area that is located inside the housing and is not intended for the detection of IR radiation incident from outside the housing; and a deflection mirror for IR radiation is arranged in the partial field of view area, which is configured to deflect reference radiation emitted by the reference radiation source into the field of view of the IR image sensor, in order to thus enable acquisition by sensor of the reference radiation by the IR image sensor in the partial field of view area.

14. The device of claim 9, wherein the access control device has a personnel airlock, in which access to the access-restricted spatial area is granted or denied in dependence on the determined body temperature (T.sub.K).

15. The device of claim 14, wherein the reference radiation source is arranged at a first position on the personnel airlock and the IR image sensor is arranged at a second position, opposite the first position with respect to the interior of the personnel airlock, in such a way that the beam path of the reference radiation source is at least partially in the field of view of the IR image sensor such that it does not cross a spatial area provided for accommodating the person to be controlled in the personnel airlock.

16. The device of claim 9, wherein the access control device comprises a coding device for generating a coded access token, wherein the code indicates, in dependence on the determined body temperature (T.sub.K), whether access to the access-restricted spatial area is granted or denied.

17. The device of claim 10, further comprising: a thermocouple for determining by sensor the reference temperature (T.sub.R) of the reference radiation source, wherein the IR image sensor or the VIS image sensor are configured so that their respective position, their orientation, or their focus are variably adjustable in order to be able to vary the image detail that can be acquired by the respective image sensor, the reference radiation source is arranged in the same housing as the IR image sensor; the field of view of the IR image sensor has a partial field of view area that is located inside the housing and is not intended for the detection of IR radiation incident from outside the housing; a deflection mirror for IR radiation is arranged in the partial field of view area, which is configured to deflect reference radiation emitted by the reference radiation source into the field of view of the IR image sensor, in order to thus enable acquisition by sensor of the reference radiation by the IR image sensor in the partial field of view area, wherein the access control device has a personnel airlock, in which access to the access-restricted spatial area is granted or denied in dependence on the determined body temperature (T.sub.K), wherein the reference radiation source is arranged at a first position on the personnel airlock and the IR image sensor is arranged at a second position, opposite the first position with respect to the interior of the personnel airlock, in such a way that the beam path of the reference radiation source is at least partially in the field of view of the IR image sensor such that it does not cross a spatial area provided for accommodating the person to be controlled in the personnel airlock, and wherein the access control device comprises a coding device for generating a coded access token, wherein the code indicates, in dependence on the determined body temperature (T.sub.K), whether access to the access-restricted spatial area is granted or denied.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the general description given above and the detailed description given below, explain the one or more embodiments of the invention.

[0035] FIG. 1 schematically shows, in a top view, an exemplary illustration of a device for access control of persons according to an embodiment of the invention.

[0036] FIG. 2 schematically shows an exemplary illustration of an IR image sensor having an integrated reference radiation source.

[0037] FIGS. 3A and 3B show a flowchart to illustrate a preferred embodiment of the method according to the invention.

[0038] FIG. 4 shows a device in the form of a kiosk for access control of persons according to a further embodiment of the invention.

DETAILED DESCRIPTION

[0039] The exemplary device 100 for access control of persons illustrated in FIG. 1 (upper part) includes a bidirectionally usable personnel airlock, which includes two opposing parallel side walls 105a and 105b and physical access restrictions in the form of a pair of doors 110a and 110b on each of their front sides. The doors of the pairs of doors 110a,b can in particular be designed as swinging doors, as shown. Alternatively or additionally to the pairs of doors 110a, b, any other type of physical access restriction can also be provided, for example a barrier in each case. Alternatively or additionally to physical access restrictions, signaling can also be provided that signals whether the access is free or blocked. For example, a light source, such as a type of traffic signal, or an acoustic signal can be provided for this purpose.

[0040] The side walls 105a,b and the pairs of doors 110a,b define a spatial area 115 in the interior of the personnel airlock, which is intended to accommodate a person P to be controlled during the control and to be used as a passage area into an access-restricted spatial area secured by the device 100. Since the exemplary personnel airlock is usable bidirectionally, it can be used to secure both the entry and the exit from the access-restricted spatial area.

[0041] In the following, unless otherwise described, it is assumed for the purpose of explanation (in particular of FIG. 3) that the access-restricted spatial area (not shown) in FIG. 1 is on the right side of the personnel airlock, so that the device 100 is to be passed from left to right to enter the access-restricted spatial area.

[0042] In this case, the pair of doors 110a is used as an entrance to the personnel airlock and in particular has the purpose of isolating people, in order to allow a single person at a time to enter the spatial area 115 for control by corresponding brief opening, ideally combined with a subsequent sensory control of the number of persons present at the same time in the spatial area 115, and to block access for other persons for as long as the person P is in the spatial area 115 for control.

[0043] In the following it is assumed that the access control takes place with regard to two control aspects, namely on the one hand an authentication of the person P, so that only authorized persons can pass the device 100, and on the other hand a measurement of the body temperature of the respective person to be controlled in order to detect a possibly elevated temperature (fever) and to only let people pass whose body temperature T.sub.K is not classified as elevated temperature or fever according to a temperature criterion TT.

[0044] The authentication can take place in various ways, for example by facial recognition, fingerprint recognition, PIN input, iris scan, or other known authentication methods. Multiple such authentication methods can also be combined. The device 100 includes appropriate sensors and/or user interfaces (for example for entering a PIN) for carrying out the authentication and a controller 140a, b for each passage direction. The controllers 140a, b for the two passage directions can also be combined in a single controller. In addition, the sensors or the user interfaces, or both, can be combined with the respective controller 140a,b as a unit. The controllers 140a,b are used for the, in particular computer program-based, control of the device 100, in particular when carrying out the method according to the invention, for example according to FIG. 3.

[0045] The device 100 also includes an image sensor 120a or 120b for each passage direction. As shown enlarged in the lower part of FIG. 1, each of these image sensors 120a,b includes an IR image sensor 121a or 121b for recording thermal images in the infrared wavelength range (IR) and a VIS image sensor 122a or 122b for recording images in the visible wavelength range (VIS). The IR and VIS image sensors can optionally (i)—as shown in FIG. 1—be housed together in a common housing or also (ii) separately, in particular in separate housings. The image sensors 120a,b are aligned in such a way that the field of view of the respective image sensors 121a,b and 122a,b is directed into the spatial area 115 in order to be able to record a respective image of a person P present in this spatial area 115, at least when the person is positioned in front of and facing toward the corresponding image sensor 120a or 120b. The relative arrangement of the respective IR image sensor 121a,b and the associated VIS image sensor 122a,b is known to the respective controller 140a,b or the image sensors 120a,b itself, so that a perspective image correction can be carried out on the basis of this information in order to be able to compute an undistorted, perspective-adapted superposition of the respective images supplied by the IR image sensor 121a or 121b and its respectively associated VIS image sensor 122 or 122b.

[0046] In the field of view of each of the IR image sensors 121a and 121b, a reference radiation source 125a and 125b is provided on the personnel airlock, which is used to supply a standard for calibrating the respective IR image sensor (in particular its sensor signal evaluation). The reference radiation sources 125a,b are preferably designed at least approximately as blackbody radiators, so that the infrared reference radiation they emit is at least largely independent in terms of its intensity and spectral distribution of the further properties of the reference radiation source and its surface and only, or at least predominantly, depends on its temperature. If the temperature of the reference radiation source is known, the intensity and the spectral distribution of the reference radiation emitted by it are therefore also known. To measure its respective current temperature, each of the reference radiation sources 125a, b includes a thermocouple 130a or 130b, which is able to measure the current temperature of the associated reference radiation source 125a, b, ideally with a degree of accuracy <1° C., and to transmit this to the associated controller 140a, b or the associated IR image sensor 121a, b for the purpose of calibration.

[0047] The respective beam path 135a,b of the reference radiation is guided within the device 100 in such a way that it does not cross the spatial area 115, so that an interruption of the beam path by a person P to be controlled in the spatial area 115 is unlikely or even impossible.

[0048] The image sensors 120a, b can be made configurable in such a way that their respective position, orientation, or focus are variably adjustable, in order to be able to vary the image detail that can be acquired by the respective image sensor. The configurability is implemented in such a way that at each position, orientation, or each focus, the reference radiation for the purpose of calibration is at least temporarily in the field of view of the associated IR image sensor 121a or 121b during the calibration process.

[0049] In particular, the housing in which the two sensors 121a and 122a or 121b and 122b are arranged (cf. image sensors 120a,b in FIG. 1) can be inclination-adjustable and/or rotatable and/or vertically-adjustable. The adjustability can in particular be automated, depending on the position or size of the person P. The camera is then, for example, able to recognize whether the person P is not in the image detail or only partially in the image (for example in the case of smaller people). An automatic adjustment then takes place accordingly in order to optimally align the image detail with the person P to be acquired by the image sensor. It is also conceivable that each sensor (IR and VIS) 121a and 122a or 121b and 122b is respectively arranged in its own movable housing. The controller (140a,b in FIG. 1) that may include a user interface can also be designed to be vertically-adjustable, in particular as a complete unit (i.e., including the two sensors 121a and 122a or 121b and 122b), in particular in the manner of a lift that moves the entire unit vertically.

[0050] FIG. 2 shows an embodiment 200 of an IR image sensor device, in particular for the device 100, in which, unlike the variant described in FIG. 1, a reference radiation source 270 is already integrated in the same housing 210 with an IR image sensor 220 as a unit.

[0051] In this case, the IR image sensor 220 has a maximum field of view 230, which typically has a conical or three-dimensional contour centered around the optical access 240 of the IR image sensor 220. In the housing 210 there is a housing opening 250 which is used as a viewing opening of the IR image sensor 220 into its external field of view 260 which is delimited by the housing opening 250 and which represents a partial area of the maximum field of view 230.

[0052] In addition, a reference radiation source 270 for IR radiation, for example a heatable metal plate, is located in the housing 210. The reference radiation source 270 is preferably designed at least approximately as a black body radiator. Furthermore, a thermocouple 280 is provided on (cf. FIG. 2 main part top) or in (cf. FIG. 2 section at the lower end of the figure) the reference radiation source 270 in order to measure the respective current temperature of the reference radiation source 270 as a reference temperature in accordance with the explanations already given for FIG. 1. The detail in the lower part of FIG. 2 illustrates an exemplary embodiment of a combination of reference radiation source 270 and thermocouple 280 that is an alternative to that in the upper main part of the figure. Here, the reference radiation source 270 has a heating block 270c optionally provided with a heater, which can in particular be a metal block and acts as a heat source or heat buffer. A layer 270b, in particular as a coating, which acts as a blackbody radiator, is dark, and essentially does not reflect light or only slightly reflects light, is provided on the heating block 270c, which can be supplied with heat by the heating block 270c and typically assumes its temperature. In the heating block 270c, the thermocouple 280 is arranged, at least in sections, in a cavity thereof, due to which a direct and thus particularly precise and reliable temperature measurement of the temperature of the heating block and thus of the reference radiation source 270 as a whole can be achieved. It is preferably a high-precision thermocouple (PT 100). In particular for the purpose of optimal heat conduction, it can be embedded in the cavity of the heating block 270c using a temperature contact paste. A measurement signal output of the thermocouple 280 is connected to a signal converter 280a, which itself can also be designed as part of the thermocouple 280 and which is configured to convert the measurement signal of the thermocouple 280 into a signal suitable for further processing by the IR image sensor, which represents the measured temperature of the reference radiation source 270 or a dependent variable derived therefrom. This signal thus assigns the measured temperature as reference temperature T.sub.R for the purpose of calibrating the radiation of the reference radiation source.

[0053] In the embodiment 200 shown in FIG. 2, the reference radiation source 270 is not itself arranged in the field of view of the IR image sensor 220. Instead, a deflection mirror 290 is provided on the inner wall of the housing 210, which in particular can include a polished metal surface, for example a polished stainless steel surface. This surface of the mirror 290 can be provided in addition to the housing wall or can already be formed by the inside of the housing wall of the housing 210 itself.

[0054] The relative position and orientation of the reference radiation source 270 and the deflection mirror 290 are provided in such a way that the beam path 270a for IR radiation originating from the reference radiation source 270 is imaged at least partially in the maximum field of view 230 of the IR image sensor 220 by the deflection mirror 290, so that it can acquire the reference radiation reflected by the deflection mirror 290 using an image sensor. It is advantageous if the arrangement of the reference radiation source 270 and the deflection mirror 290 is selected such that the reference radiation reflected by the deflection mirror 290 is in the maximum field of view 230 of the image sensor 220, but not in its limited external field of view 260, but in a partial field of view area 295 lying outside of the limited external field of view 260. Thus, the reference radiation can be received without being superimposed on the thermal image acquired from the external field of view 260 and can be evaluated uninfluenced by it, at least essentially. The embodiment 200 thus represents a particularly compact and reliable option for implementing the IR image sensor. In particular, no beam path external to the housing is required for the reference radiation.

[0055] An exemplary embodiment of a method 300 according to the invention for personal access control is illustrated in the two associated FIGS. 3A and 3B, which overall show a flow chart and are graphically connected by a “connector” C. For purposes of explanation, the method 300 is described below with exemplary, non-limiting reference to FIG. 1 and in the passage from left to right therein, however, this should not be construed as a restriction. If the passage direction is reversed, the method proceeds accordingly, wherein then the elements of the device 100 marked with “a”, in particular the controller 140a and the image sensor 120a, are used.

[0056] The method 300 includes a step 305 in which an infrared reference radiation 135b emitted by the reference radiation source 125b at the current temperature T.sub.R is acquired by sensor with the aid of the IR image sensor 121b. The current temperature T.sub.R can in particular be measured using the thermocouple 130b. Then, in a further step 310, the IR image sensor 121b is calibrated with respect to the reference radiation 135b used as a calibration standard. In the context of the calibration, based on the measured temperature T.sub.R and the acquired reference radiation 135b, the IR image sensor 121b, or an evaluation unit assigned thereto, in particular evaluation electronics or evaluation software, is configured in such a way that further temperature measurements based on a thermal image recorded by the IR image sensor 121b of the reference radiation 135b emitted at the reference temperature T.sub.R supply the actual temperature T.sub.R within the scope of the measurement accuracy. The evaluation unit can be formed in particular by the controller 140b.

[0057] After the calibration has taken place, the device 100 is ready for use to carry out a personal access control. If a person P to be controlled is in the spatial area 115 of the device 100 after passing through the access opening of the personnel airlock closable by the pair of doors 110a, they are prompted, for example by a corresponding display on a graphical user interface or via a speech output, to turn to the image sensor 120b, in order to be acquired by an image sensor.

[0058] Then, in step 315, a thermal image of the face of the person P is recorded using the IR image sensor 121b and corresponding thermal image data representing the thermal image are generated. At the same time, in a step 320, an image of the face of the person P in the visible wavelength range (VIS) is acquired by an image sensor by the VIS image sensor 122b, and image data representing the image are generated. In order to be able to superimpose the thermal image and the image without errors, a perspective correction of the image data and/or of the thermal image data is now carried out in a step 325, so that the thermal image and the VIS image correspond to the same perspective of the person P after the correction. In this case, the correction takes place on the basis of the previously known relative location and position of the two image sensors 121b and 122b in relation to one another.

[0059] In order to ensure a sufficiently high level of reliability for the fever detection and an authentication to be carried out on the basis of biometric face recognition, moreover, in a step 330, the area proportion F of the image of the face relative to the total area A of the entire image represented by the image data (at same image resolution) is computed on the basis of the image data.

[0060] If a subsequent test in step 340 reveals that the ratio F/A is not above a certain image area proportion criterion R (340—no), it is assumed that the face is not represented sufficiently large in the image to ensure the further method 300 proceeds correctly with regard to the correctness of the decision to be made regarding the granting or denying access of the person P to the access-restricted spatial area secured by the device 100. A jump is therefore made back to step 315 in order to carry out another image acquisition.

[0061] Otherwise (340—yes), the method continues with a step 345, in which at least one biometric feature of the person P, for example the positions of the eyes and the nose, is first detected and measured based on the image data. Based on this, multiple partial areas of the face are identified in the image, for example the forehead or the area around the eyes or the cheeks of the person P.

[0062] By superimposing the image according to the image data and the thermal image according to the thermal image data, a local body temperature taken from the corresponding image area of the thermal image can now be assigned in a step 350 to each of the identified partial areas. For example, the maximum temperature occurring in its associated image area of the thermal image can be determined as the associated local body temperature for each partial area. Alternatively, for example, an average temperature over the image area of the thermal image that corresponds to the partial area can also be determined as the local body temperature of the partial area.

[0063] As a further security measure to increase the reliability of the method, a plausibility check can be carried out in a step 355, in which the local body temperatures for the different partial areas are compared to one another or in each case to an associated predetermined temperature standard. Such a temperature standard can exist, for example, in the form of data determined on the basis of statistical surveys. Certain plausibility criteria, which can also be determined on a statistical basis, are also defined for a relative comparison of the local body temperatures to one another, in order to be able to determine whether any temperature differences between the respective determined local body temperatures for different partial areas of the face are within a typical range, or due to a deviation therefrom indicate an increased probability of a measurement error.

[0064] In dependence on the result of the plausibility check, a jump is then made back to step 315 in a step 360 if the plausibility check was not passed (360—no). Otherwise (360—yes), an overall body temperature T.sub.K of the person P is ascertained on the basis of the local body temperatures determined for the various partial areas, which have now been checked for plausibility. In particular, this can be done in such a way that the highest of the local body temperatures is determined as the overall body temperature T.sub.K (selection criterion). However, other variants of selection criteria are also conceivable here, in particular an averaging, which is weighted in particular, over the various local body temperatures or a selection of a subset of the local temperatures with subsequent averaging over them.

[0065] In a step 370 it is now checked whether the overall body temperature T.sub.K is above a predetermined temperature threshold TT which defines an access criterion in the form of a criterion for an elevated body temperature. If this is the case (370—yes), then in a step 375 access is denied and an alarm or a discrete alarm message is optionally triggered to the terminal of a predetermined recipient, for example a security guard. The physical access restriction to the access-restricted spatial area provided in the form of the pair of doors 110b remains or is (if not already closed) closed.

[0066] Otherwise (370—no), the person is also authenticated on the basis of the image data acquired by the image sensor 122b, for which purpose in particular the same biometric features can be used that were already previously used to determine the partial areas of the image of the face. If the authentication is successful and it has the result that the person P is authorized to access the access-restricted spatial area (390—yes), a step 390 branches to step 395, in which access to the access-restricted spatial area is granted and in particular the physical access restriction in the form of the pair of doors 110b is opened. Otherwise (390—no), the system branches to step 375, and access is accordingly denied.

[0067] FIG. 4 illustrates a further exemplary embodiment 400 of a device for personal access control, which is in the form of a kiosk, as an alternative to FIG. 1. The personal access control takes place here in particular in that the person P authenticates himself at the kiosk and is subjected at the same time to a body temperature measurement. For this purpose, the device 400 has an IR image sensor 410, which has an integrated reference radiation source for its calibration, as illustrated in FIG. 2, for example. Furthermore, a VIS image sensor 420 and one or —as shown—multiple illumination elements 430 for illuminating the field of view of the image sensors 410 and 420 are provided. In order to avoid or reduce disruptive, planar light reflections on the eyes or glasses of the person P, polarization filters can be provided on the illumination elements. The device can also include various elements of a user interface, in particular for the purpose of authenticating the person P, in particular a display device 440—preferably embodied as a touch-sensitive screen (touchscreen)—an ID card reader 450, a fingerprint sensor 460, and/or a printer 470 for printing a ticket on which a code indicating whether access to the access-restricted spatial area is granted or denied is printed in dependence on the result of the authentication and the body temperature measurement. In addition, in particular in the case of access denial by the code, a reason for the access denial can also be indicated, for example failed authentication due to an invalid ID or ID recognized as forged or biometric features of the person P, or a body temperature that is too high.

[0068] While at least one exemplary embodiment has been described above, it is to be noted that a large number of variations thereto exist. It is also to be noted that the exemplary embodiments described only represent non-limiting examples, and are not intended to restrict the scope, the applicability, or the configuration of the devices and methods described herein. Rather, the preceding description will provide those skilled in the art with guidance for implementing at least one exemplary embodiment, wherein it is apparent that various changes in the operation and arrangement of elements described in an exemplary embodiment may be made without departing from the scope of the subject matter defined in the appended claims and its legal equivalents.