System and method for testing a device-under-test

Abstract

The invention relates to a system in particular a quantum sensor system, for testing a device-under-test, DUT, comprising: an optically excitable medium which is arranged to receive electromagnetic, EM, radiation emitted by the DUT, at least one light source configured to irradiate the medium with at least one light beam, wherein the medium is optically excited by the at least one light beam, a field generator unit configured to generate an electric and/or magnetic field within the medium, wherein a resonance frequency of the excited medium is modified by an amplitude of the electric and/or magnetic field, wherein an optical parameter, in particular a luminescence, of the exited medium is locally modified if a frequency of the EM radiation corresponds to the resonance frequency at a position in the medium, an image detector configured to acquire an image of the medium, wherein the image shows an intensity profile that results from the modification of the optical parameter, a processor configured to analyze the DUT based on the acquired image.

Claims

1. A system in particular a quantum sensor system, for testing a device-under-test, DUT, comprising: an optically excitable medium which is arranged to receive electromagnetic, EM, radiation emitted by the DUT, at least one light source configured to irradiate the medium with at least one light beam, wherein the medium is optically excited by the at least one light beam, a field generator unit configured to generate an electric and/or magnetic field within the medium, wherein a resonance frequency of the excited medium is modified by an amplitude of the electric and/or magnetic field, wherein an optical parameter, in particular a luminescence, of the exited medium is locally modified if a frequency of the EM radiation corresponds to the resonance frequency at a position in the medium, an image detector configured to acquire an image of the medium, wherein the image shows an intensity profile that results from the modification of the optical parameter, and a processor configured to analyze the DUT based on the acquired image.

2. The system according to claim 1, wherein the processor is configured to extract and/or reconstruct a phase information of the EM radiation from the intensity profile.

3. The system according to claim 2, further comprising an emitter unit, in particular a local oscillator, wherein the emitter unit is configured to emit an EM signal towards the medium, wherein the EM radiation emitted by the DUT is superimposed by the EM signal within the medium, and wherein the processor is configured to extract and/or reconstruct the phase information of the EM radiation from a change in the intensity profile resulting from the superposition of the EM radiation and the EM signal within the medium.

4. The system according to claim 1, wherein the amplitude of the electric and/or magnetic field varies at different positions in the excited medium, resulting in different resonance frequencies at said positions, wherein the processor is configured to determine the frequency of the EM radiation based on a location and/or a shape of features in the intensity profile.

5. The system according to claim 1, wherein the amplitude of the electric and/or magnetic field is homogeneous in the excited medium, resulting in an equal resonance frequency everywhere in the medium, wherein the processor is configured to determine a location of a source of the EM radiation on the DUT based on a location and/or a shape of features in the intensity profile.

6. The system according to claim 1, wherein the system comprises two light sources configured to irradiate the medium with two light beams, wherein of each of the two light beams has a frequency that corresponds to a different resonance frequency of the medium.

7. The system according to claim 1, wherein the field generator unit comprises a capacitor.

8. The system according to claim 1, wherein the optically excitable medium is a gas, in particular a caesium gas, wherein the gas is stored in a gas cell.

9. The system according to claim 1, wherein the optically excitable medium is a solid material, in particular diamond.

10. The system according to claim 1, wherein the DUT is a printed circuit board, PCB.

11. A method for testing a device-under-test, DUT, comprising the steps: receiving an electromagnetic, EM, radiation emitted by the DUT at an optically excitable medium, irradiating the medium with at least one light beam; wherein the medium is optically excited by the at least one light beam generating an electric and/or magnetic field within the medium, wherein a resonance frequency of the excited medium is modified by an amplitude of the electric and/or magnetic field, wherein an optical parameter, in particular a luminescence, of the exited medium is locally modified if a frequency of the EM radiation corresponds to the resonance frequency at a position in the medium, acquiring an image of the medium, wherein the image shows an intensity profile that results from the modification of the optical parameter, and analyzing the DUT based on the acquired image.

12. The method according to claim 11, wherein the step of analyzing the DUT comprises: extracting and/or reconstructing a phase information of the EM radiation from the intensity profile.

13. The method according to claim 12, wherein the method further comprises: emitting an EM signal towards the medium, wherein the EM radiation emitted by the DUT is superimposed by the EM signal within the medium; and wherein the phase information of the EM radiation is extracted and/or reconstructed from a change in the intensity profile resulting from the superposition of the EM radiation and the EM signal within the medium.

14. The method according to claim 11, wherein the amplitude of the electric and/or magnetic field varies at different positions in the excited medium, resulting in a variation of the resonance frequency at said positions, wherein the step of analyzing the DUT comprises: determining the frequency of the EM radiation based on a location and/or a shape of features in the intensity profile.

15. The method according to claim 11, wherein the amplitude of the electric and/or magnetic field is homogeneous in the excited medium, resulting in an equal resonance frequency everywhere in the medium, wherein the step of analyzing the DUT comprises: determining a location of a source of the EM radiation on the DUT based on a location and/or a shape of features in the intensity profile.

16. The method according to claim 11, wherein the medium is irradiated with two light beams, wherein of each of the two light beams has a frequency that corresponds to a different resonance frequency of the medium.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in the followings together with the figures.

(2) FIG. 1 shows a schematic diagram of a system for testing a DUT according to an embodiment;

(3) FIG. 2 shows a schematic diagram of a system for testing a DUT according to an embodiment;

(4) FIG. 3 shows a schematic diagram of a system for testing a DUT according to an embodiment;

(5) FIG. 4 shows a schematic diagram of a system for testing a DUT according to an embodiment;

(6) FIG. 5a-b show schematic diagrams of measurement schemes for localizing an EM radiation source on a DUT according to embodiments;

(7) FIG. 6 shows a schematic diagram of an assembly line according to an embodiment; and

(8) FIG. 7 shows a schematic diagram of a method for testing a DUT according to an embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(9) FIG. 1 shows a schematic diagram of a system 100 for testing a DUT 101 according to an embodiment.

(10) The system 100 comprises an optically excitable medium 103 which is arranged to receive EM radiation emitted by the DUT 101, at least one light source configured to irradiate the medium with at least one light beam 105a, 105b, wherein the medium 103 is optically excited by the at least one light beam 105a, 105b, and a field generator unit configured to generate an electric and/or magnetic field within the medium, wherein a resonance frequency of the excited medium 103 is modified by an amplitude of the electric and/or magnetic field, and wherein an optical parameter, in particular a luminescence, of the exited medium 103 is locally modified if a frequency of the EM radiation corresponds to the resonance frequency at a position in the medium 103. The system 100 further comprises an image detector 107 configured to acquire an image of the medium 103, wherein the image shows an intensity profile that results from the modification of the optical parameter, and a processor configured to analyze the DUT 101 based on the acquired image.

(11) The DUT 101 can comprises at least one emitter for the EM radiation. The EM radiation can be a microwave radiation with a frequency of, for instance, 50 MHz. For example, the DUT 101 is a PCB, which is tested by the system 100.

(12) The optically excitable medium 103 can be gaseous, e.g. a caesium vapor, and can be arranged in a glass cell. Alternatively, the optically excitable medium 103 can be a solid material, such as diamond. The optical excitation can be a Rydberg state or an electromagnetically induced transparency (EIT) of the medium 103.

(13) Preferably, the system 100 comprises two light sources, in particular lasers that generate two light beams 105a, 105b to optically excite the medium. Each light beam 105a, 105b can have a different wavelength, wherein each wavelength is tuned to excite a different state of the medium. At least one of the light beams 105a, 105b can be a green laser light.

(14) If the medium 103 is a caesium gas, the first light source can be configured to illuminate the caesium gas with light at a wavelength of ca. 852 nm, and the second light source light source can be configured to illuminate the caesium gas with light at a wavelength of ca. 509-517 nm.

(15) The image detector 107 can be a camera. The image detector 107 can comprise an objective and a band pass filter for the wavelength of at least one of the light beams 105a, 105b, in particular for green light.

(16) The field generator unit can comprise a capacitor 111. The capacitor 111 can be configured to generate a static, in particular non-oscillating, electric field in the medium 103, wherein an amplitude of the electric field is tunable. The capacitor 111 may comprise capacitor plates on two opposite sides of the medium 103. In an embodiment, the field generator further comprises a magnetic field source (not shown) for generating a static magnetic field in the medium 103.

(17) The field generator unit can further be configured to generate a continuous electric and/or magnetic field, i.e. a field with gradually changing amplitude, in the medium 103.

(18) The system 100 can further comprise an emitter unit 109 to generate an EM signal. The emitter unit 109 can be a local oscillator. The EM signal can be a microwave signal with a similar frequency as the EM signal generated by the DUT. Preferably, the EM radiation emitted by the DUT 101 mixes with the EM radiation generated by the emitter unit 109 within the medium. The phase of the EM radiation can be determined based on this superposition of the EM radiation and the EM signal. Preferably, the optically excitable medium 103, the field generator unit and the image detector 107 form a quantum sensor.

(19) FIG. 2 shows a schematic diagram of the system 100 for testing the DUT 101 according to an embodiment.

(20) In the system 100 shown in FIG. 2, the field generator unit generates a magnetic field 203 with a continuously changing amplitude, resulting in a continuously changing resonance frequency in the medium 103. In other words, the resonance frequency varies and has a continuous distribution in the excited medium 103.

(21) The DUT 101 emits the EM radiation 201 from a certain location, e.g. an antenna on the DUT 101. For example, the EM radiation 201 has a frequency of 50 MHz. At a certain location in the medium 103, the resonance frequency of the medium 103 can match the frequency of the EM radiation. At said location the EM radiation 201 modifies the optical parameter, in particular the luminesce, of the medium 103, which can be detected by the image detector 107. In particular, the processor is configured to analyze the acquired image and to determine the frequency of the EM radiation based on the location and/or a shape of features in the intensity profile depicted in the image. The processor 102 is illustrated in FIG. 2.

(22) In particular, the system 100 shown in FIG. 2 is a quantum spectrum analyzer system, which measures in a frequency domain.

(23) FIG. 3 shows a schematic diagram of the system 100 for testing the DUT 101 according to another embodiment.

(24) In the system 100 shown in FIG. 3, the field generator unit generates a constant magnetic field 203 resulting in a constant resonance frequency everywhere in the excited medium 103.

(25) The constant magnetic field 203 can be configured to set the resonance frequency of the medium 103 to the frequency of the EM radiation 201 which was preferably detected in an earlier step using a continuous magnetic field 203, as shown in FIG. 2. In particular, the magnetic field 203 is adjusted to apply a 5 MHz filter.

(26) Preferably, the EM radiation 201 modifies the optical parameter, in particular the luminescence, of the medium 103, wherein a location and shape of the modification depends on the spatial coordinates on the DUT 201 from which the EM radiation 201 is emitted. In particular, the processor is configured to determine the location of a source of the EM radiation 201 on the DUT 101 based on a location and/or a shape of features in the intensity profile.

(27) FIG. 4 shows a schematic diagram of the system 100 for testing the DUT 101 according to another embodiment.

(28) The system 100 in FIG. 4 comprises the local oscillator 109, which generates an EM signal with a frequency that is similar to the frequency of the EM radiation. Preferably, the frequency of the EM signal deviates from the frequency of the EM radiation by less than 1%, in particular less than 0.1%, more particular less than 0.01%. For instance, both the EM signal and the EM radiation are microwave signals. The EM radiation emitted by the DUT 101 can be superimposed by the EM signal within the medium.

(29) Based on this superposition of EM radiation and EM signal within the medium, the phase of the EM radiation can be determined accurately. For example, the local oscillator 109 is locally displaced while emitting the EM signal, resulting in a shift of the relative phase between the EM signal and the EM radiation within the medium. This shift of the relative phase causes an observable change in the intensity profile. The processor can be configured to determine the phase of the EM radiation based on the observed change of the relative phase. Thereby, the processor can take further parameters into account, such as: the displacement of the emitter unit, the emission angle of the EM signal, the intensity of the EM signal, and/or a propagation constant of the medium.

(30) By tuning the amplitude of the magnetic field and/or the frequency of the EM signal emitted by the local oscillator, the system can sweep through known emission frequencies of the DUT and measure a location of an emitter of the EM radiation and/or the phase of the EM radiation at said frequencies.

(31) The resonant frequency of the medium 103 can further be tuned with a constant electric field instead of or in addition to the magnetic field. In particular, the resonance frequency of the medium 103 may also be influenced by an oscillation frequency of the electric and/or magnetic field.

(32) The system 100 can further comprise a shielding 401, which is arranged between the DUT 101 and the medium 103. The shielding 401 can be configured to shield the DUT 101 from the magnetic field 203. For example, the shielding 401 is made of a Mu-metal.

(33) In particular, the systems 100 shown in FIGS. 3 and 4 are quantum spectrum analyzer systems, which measure in a spatial domain.

(34) FIGS. 5a and 5b show schematic diagrams of measurement schemes for localizing an EM radiation source on the DUT 101 according to embodiments. In particular, the measurements shown in FIGS. 5a and 5b were carried out by one of the systems 100 shown in FIG. 3 or FIG. 4.

(35) FIG. 5a shows a measurement, where the system 100, in particular the image detector 107, is arranged directly above the source of the EM radiation 201 on the DUT 101. Thereby, the EM radiation 201 is assumed to be a periodic signal that is radially irradiated from a point in space. The corresponding intensity profile 303 shows the expected phase image for this configuration, which is, for instance, radially symmetric and centered in the intensity profile 303. In particular, the intensity profile corresponds to an intensity distribution.

(36) FIG. 5b shows a measurement, where the sensor system, in particular the image detector 107, is laterally shifted to the source of the EM radiation 201 on the DUT 101. Again, the EM radiation 201 is assumed to be a periodic signal that is radially irradiated from a point in space. The corresponding intensity profile 303 shows the expected phase image for this configuration, which, for instance, shows a section of a radial phase distribution.

(37) The processor of the system 100 can be configured to analyze the phase images and determine the location on the DUT 101 from which the EM radiation 201 was emitted based on the features in the image. The processor can further be configured to determine the phase of the EM radiation 201 based on the phase image.

(38) FIG. 6 shows a schematic diagram of an assembly line 600 according to an embodiment.

(39) The assembly line 600 comprises a system 100 for testing DUTs 101, for example any one of the systems 100 shown in FIGS. 1 to 5. The assembly line 600 can be an automated rapid assembly line for PCB screening, wherein each PCB 101a-c on the line is a DUT 101 that is tested by the system 100. In particular, the PCBs iota-c are post-assembly PCBs.

(40) The assembly line 600 can comprise a conveyer band 601 for moving the PCBs 101a-c to guide the PCBs 101a-c past the system 100, wherein the system 100 can be configured to perform a contactless screening of each PCB 101a-c. Preferably, if a PCB 101a-c passes the screening it is moved forward, and if a PCB 101a-c fails the screening, it is moved into a secondary band for further testing. In this way, the PCBs 101a-c can be screening quickly during or after a production cycle.

(41) FIG. 7 shows a schematic diagram of a method 70 for testing the DUT 101. In particular, the method 70 can be carried out by any one of the systems 100 shown in FIGS. 1 to 6.

(42) The method 70 comprises: receiving 71 the EM radiation 201 emitted by the DUT 101 at the optically excitable medium 103, irradiating 73 the medium 103 with at least one light beam 105a, 105b; wherein the medium 103 is optically excited by the at least one light beam 105a, 105b, generating 75 the electric and/or magnetic field within the medium 103, wherein the resonance frequency of the excited medium 103 is modified by the amplitude and/or the oscillation frequency of the electric and/or magnetic field, wherein the optical parameter, in particular the luminescence, of the exited medium 103 is locally modified if a frequency of the EM radiation 201 corresponds to the resonance frequency at a position in the medium 103, acquiring 77 an image of the medium 103, wherein the image shows an intensity profile 303 that results from the modification of the optical parameter, and analyzing 79 the DUT 101 based on the acquired image.

(43) Preferably, the step of analyzing 79 the DUT 101 comprises: extracting and/or reconstructing a phase information of the EM radiation 201 from the intensity profile 303.

(44) Preferably the method 70 further comprises: emitting an EM signal towards the medium 103, wherein the EM radiation 201 emitted by the DUT 101 is superimposed by the EM signal within the medium 103; and
wherein the phase information of the EM radiation 201 is extracted and/or reconstructed from a change in the intensity profile resulting from the superposition of the EM radiation 201 and the EM signal within the medium 103.

(45) Preferably, the amplitude of the electric and/or magnetic field varies at different positions within the excited medium 103, resulting in a variation of the resonance frequency at said positions, wherein the step of analyzing 79 the DUT 101 further comprises: determining the frequency of the EM radiation 201 based on a location and/or a shape of features in the intensity profile 303.

(46) Preferably, the amplitude of the electric and/or magnetic field is homogeneous in the excited medium 103, resulting in an equal resonance frequency everywhere within the medium 103, wherein the step of analyzing 79 the DUT 101 further comprises: determining a location of a source of the EM radiation 201 on the DUT 101 based on a location and/or a shape of features in the intensity profile 303.

(47) The medium 103 can be irradiated with two light beams 105a, 105b, wherein of each of the two light beams 105a, 105b can have a frequency that corresponds to a different resonance frequency of the medium 103.

(48) All features of all embodiments described, shown and/or claimed herein can be combined with each other.