System for sensor protection in electronic imaging applications

Abstract

To provide an improved system and method for protecting an imaging sensor from overexposure.SOLUTION: A system comprises a beam control device configured to provide a beam signal based on an incoming beam signal, where the beam signal comprises altered beam intensity, where the beam control device is further configured to receive a control signal and to activate based on the control signal. The system further comprises a sensor configured to capture the beam signal and to provide a capture signal based on the beam signal, and a control module configured to provide the control signal to the beam control device, to generate an exposure value based on the capture signal, and to modify the control signal based on the exposure value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to particle beam imaging, and in particular to diffraction imaging based on electron beams. More specifically, the present invention relates to a system for sensor protection in electron imaging applications based on controlling the beam intensity of a beam signal exposed to an imaging sensor. [Background technology]

[0002] Traditionally, signal dose protection for image sensors can be achieved using optical models to derive the beam intensity at the image sensor from the lens currents, however, this can be difficult to extend to imaging applications based on diffraction, energy-filtered transmission electron microscopy (EFTEM), and / or electron energy loss spectroscopy (EELS).

[0003] By using direct electron detectors (DEDs), an increased signal-to-noise ratio (SNR) can be achieved, which can be used to reduce the beam intensity to limit damage caused by the electron beam hitting the sample. However, DEDs are more likely to cause overexposure that can permanently increase the dark current, resulting in a reduced SNR and reduced dynamic range, which can result in the imaging sensor becoming inoperable. The signal dose can be related to the cumulative dose over the lifetime of the imaging sensor. A short exposure to high current densities can already cause permanent damage.

[0004] Direct detectors may be blocked for use in diffraction mode because they may be damaged by high peak currents projected onto the imaging sensor. It may be difficult to ensure that the maximum local current incident on the sensor is below system safety limits. The system is also at risk due to possible human error, such as an operator forgetting and / or not placing the beam stop correctly, not aligning the optics correctly, etc., so that unexpected high beam intensities may hit the sensor. This may result in severe sensor damage after only a few occurrences. Also, when performing alignment in diffraction mode, the central beam may move and miss the beam stop. Additionally and / or alternatively, alignment may require the central beam to be visible, e.g., for focus purposes or astigmatism correction, and again, full exposure of the central beam may damage the sensor. Summary of the Invention

[0005] In view of the above, the present invention seeks to overcome or at least mitigate the shortcomings and disadvantages of known electronic imaging systems. It is an object of the present invention to provide an improved system and method for protecting an image sensor from overexposure.

[0006] These objectives are achieved by the systems and methods of the present invention.

[0007] According to a first aspect, the present invention relates to a system for sensor protection in particle imaging applications, comprising a beam control device (BCD) configured to provide a beam signal based on an incident beam signal, the beam signal comprising a modified beam intensity.

[0008] The particles can be charged, preferably the particles are electrons. The system can be an electron microscope, for example a scanning electron microscope and / or a transmission electron microscope. The system can be configured to capture the diffraction pattern of a charged particle beam, in particular an electron beam. Due to the varying intensity of the beam, the beam intensity can exceed a maximum intensity threshold that the sensor of the system can capture without substantially reducing the lifetime of the sensor or causing irreversible damage to the sensor. Therefore, the system comprises a BCD configured to protect the sensor by shielding it from the beam and / or at least reduce the beam intensity to protect the sensor and prevent overexposure.

[0009] The BCD can also be configured to protect the sample by being positioned upstream of the sample and / or specimen. This changes the beam intensity of the initial beam before the beam interacts with the sample and / or before the beam signal is captured by the sensor. The system can be configured to specifically capture particle beams directly, where the beam can include high peak currents projected onto the sensor. Typically, such high peak currents, i.e., high beam intensities, preclude the use of direct detectors in diffraction mode.

[0010] In particular, due to the high variance, i.e. dynamic range, of the incident beam, it is beneficial to control the maximum local current, i.e. the maximum local beam intensity, provided to the sensor. This can ensure that the maximum local current is within the safety limits specified by the sensor. The invention provides the advantage that the sensor can be protected from beam intensities that exceed the maximum allowable intensity. Thus, the lifetime of the sensor is increased. In the diffraction mode, it can be advantageous to block a part of the beam signal, preferably the central non-scattered beam component, which typically has the highest beam intensity. Thus, only the scattered components of the beam are provided to the sensor. The central beam component can be blocked by a beam stop, which can be manually or automatically installed. However, due to system variations or user errors, the beam stop may not intersect with the propagation trajectory of the central beam component, which can cause the high intensity central beam component to impinge on the sensor and potentially damage it. The system according to the invention achieves the advantage that such scenarios can be detected and / or predicted. Thereby, appropriate measures, i.e. reducing the beam intensity, can be automatically implemented to protect the sensor.

[0011] System variations can include operator failure to insert or remove beam stops, beam optics alignment changes, sample changes, i.e., sample degradation and / or replacement.

[0012] Providing a beam signal based on the incident beam signal can also include not providing any portion of the beam to the sensor such that the sensor is completely shielded from the beam. Alternatively, the BCD can reduce the beam intensity of the incident beam signal to a reduced beam intensity in the beam signal, which can then be provided to the sensor. The beam intensity can be varied by partial absorption, partial blocking, and / or time-varying blocking of the incident beam signal.

[0013] Typically, when alignment is performed in diffraction mode, the central component of the incident beam signal may jump and miss the beam stop. Furthermore, alignment of the system may be performed with the central beam visible to the sensor, e.g., for focus purposes or astigmatism correction.

[0014] To avoid damage to the sensor, the beam current can be increased slowly, preferably by using a shutter modulation concept. As a first step, an image can be acquired at a low beam duty cycle. The system can be configured to determine if there is a maximum current and then the duty cycle is allowed to be increased to the full duty cycle.

[0015] The present invention can further achieve the advantage that the altered beam signal, i.e. the modulated beam current, can be low enough to allow longer duration exposure by the sensor, which can be used for alignment purposes.

[0016] The modified beam intensity can be based on a time-varying intensity and / or a time-varying intensity pattern, in particular a. a blocking pattern.

[0017] The sensor may be a CMOS sensor comprising a number of sensing elements, also called pixels, in the form of photodiodes arranged in an array. Each pixel may be connected to an Analog-to-Digital Converter (ADC). The voltage across each pixel may be the result of impinging radiation, such as electrons and / or light.

[0018] The system can provide reactive dose protection. After every new optical system setting (e.g. after a magnification switch or mode switch, i.e. to diffraction or EFTEM), the system can perform a peak in the image to check that the dose is safe. This peak can include a reduced exposure, preferably the minimum beam intensity to generate the image. Based on this peak, the system can determine safe exposure conditions and start a longer peak to make sure it is still safe. This peaking can continue until the required exposure time is reached.

[0019] Preferably, the system is capable of generating short exposure times such that the sensor is not overexposed, i.e. the exposure threshold is exceeded at the beam intensity maximum and exposure time minimum, i.e. the shortest inactive interval.

[0020] The BCD may comprise a titanium shutter. The BCD may comprise a shield surrounding the shutter and configured to shield the shutter from EM radiation, respectively shielding the surroundings from EM radiation emitted by the BCD. In particular, the shield may be a shielding bushing. The shielding bushing may comprise mu-metal and / or ferrite. Preferably, the BCD is configured to achieve an exposure time interval of 10 μs or less. The exposure time interval may be defined as the time interval between BCD deactivation and BCD reactivation, i.e. performing two switching operations.

[0021] method: Generally, a trigger, e.g., a significant optical mode change, a switch to diffraction mode, etc., can cause the system to enter an evaluation mode, i.e., a peaking mode, during which the system checks whether the illumination is acceptable. After this check is performed, the normal exposure mode can be performed. Preferably, dose protection is active during the normal exposure mode, and can be activated when an exposure threshold is reached or exceeded to limit the exposure of the beam signal to the sensor.

[0022] The beam current can be slowly increased by using the BCD, i.e., shutter modulation, concept. A first image is acquired at a first duty cycle with a reduced exposure time interval. The system determines the maximum current detected for the reduced exposure and can increase to the full duty cycle when the maximum detected current per exposure falls below the respective threshold.

[0023] The modulated beam current may include a beam intensity that is low enough to allow longer exposure of the sensor, for example for alignment purposes.

[0024] The BCD can vary the intensity of the beam signal over a given time interval. Thus, the beam intensity can be modulated to, among other things, reduce the overall exposure of the beam signal to the sensor in a capture interval. The exposure of the beam signal to the sensor per capture interval can be limited by the BCD.

[0025] The system may comprise a sensor configured to capture the beam signal, in particular the modified beam signal and / or the incident beam signal, and provide a captured signal based on the beam signal. The sensor may provide a quantitative, spatially and / or temporally resolved representation of the beam signal as part of the captured signal. Preferably, the sensor is directly exposed to the beam signal, in particular in a diffraction mode of the system. The beam signal may be an incident electron beam directed to the sensor. The electron beam may be scattered from the sample and / or the electron beam may be diffracted by the sample in the beam path.

[0026] The BCD may include a blanker configured, when activated, to stop the incident beam signal from propagating through the blanker in an initial propagation direction of the incident beam signal. The beam signal may be absorbed by the blanker. The blanker may have no effect on the incident beam signal in an inactive state.

[0027] The BCD comprises a mechanical shutter configured to provide a switchable physical barrier when activated, configured to at least partially intersect the initial propagation direction of the incident beam signal. The BCD can modify the incident beam signal such that the beam signal captured by the sensor may include artifacts. In particular, the BCD can smear parts of the incident beam signal such that intensity peaks may be projected onto multiple detector wells, i.e. pixels of the sensor. This can improve the detection of overexposure, since the beam signal may overexpose multiple pixels, not just a single pixel. A single overexposed pixel may be interpreted as a malfunctioning pixel, while a group of overexposed pixels is easier to detect as a significant overexposure. This effect may arise due to a slower activation of the BCD (with respect to the faster capture rate of the sensor), i.e. the BCD moving into the beam such that refraction occurs at the edges of the BCD, for example.

[0028] At short exposure times the image will not be OK due to the slow shutter (magnetic), but this is not a problem for overexposure detection. It can still be advantageous, since the dose is smeared and easier to detect. True localized (within a pixel) overexposure may not be detectable by area filter detection methods, but would cause severe damage.

[0029] The BCD may comprise an electrostatic shutter configured to provide an electrostatic field when activated such that the initial propagation direction of the incident beam signal and the modified propagation direction of the modified beam signal are at an angle with respect to each other, particularly when the electrostatic shutter is active. This achieves the advantage that a beam signal having a modified propagation direction may be deflected such that the modified beam signal does not at least partially reach the sensor. Preferably, when the electrostatic shutter is active, the modified beam signal does not propagate towards the sensor. The electrostatic shutter may be configured to deflect the incident beam signal towards an absorbing target configured to absorb the incident beam signal.

[0030] The BCD may comprise an electromagnetic (electrodynamic) shutter configured to provide an electromagnetic field, in particular a periodic electromagnetic field, such that when activated, in particular when the electromagnetic shutter is active, the initial propagation direction of the incident beam signal and the modified propagation direction of the modified beam signal are angled with respect to each other, whereby the beam signal may be directed away from the sensor, in particular to protect the sensor from damage due to beam intensity exceeding the tolerance range of the sensor.

[0031] The BCD may comprise an attenuator configured to reduce the intensity of the incident beam when activated to provide a modified beam having an intensity substantially equal to or lower than the incident beam signal. Preferably, the attenuator may include a transmissive material configured to transmit a portion of the incident beam signal as a beam signal toward the sensor. This may result in a lower beam intensity. This may achieve the advantage of avoiding overexposure and / or reducing the beam intensity to a predetermined level. The attenuator may be adjustable so that the transmittance may be controlled. The substantially equal intensity may be achieved with a particular mode of the attenuator that maximizes the transmittance so that the beam signal provided to the sensor is only minimally altered relative to the incident beam signal. This may be a pass-through mode to provide an essentially unchanged beam signal to the sensor.

[0032] The BCD can include an aperture configured to block at least a portion of a cross-section of an incident beam signal when activated. The aperture can at least partially intersect the incident beam signal such that the beam signal provided to the sensor includes a modified beam cross-section. The aperture can block a portion of the beam that contributes to overexposure of at least a sub-area of ​​the sensor. As a result, adjusting the aperture can prevent overexposure and / or sensor damage.

[0033] The BCD may comprise a lens configured to transform the cross-section of the incident beam when activated. The lens may be a particular type of focus / defocus element with corresponding features and advantages. The lens may be an electrostatic or electromagnetic lens configured to focus the incident beam signal. The lens may be nested within a further lens element. The sample may be placed within the lens.

[0034] The BCD may comprise a mirror configured to at least partially reflect and / or deflect the incident beam signal when activated. The mirror may be semi-transmissive so that a portion of the beam signal may reach the sensor. The tilt of the mirror may be adjustable to modify the propagation direction of the reflected beam signal. The transmittance of the mirror may be adjustable to control the intensity of the transmitted component of the incident beam signal directed to the sensor. The mirror may be configured to at least partially direct the incident beam signal to an absorbing target and / or other components of the system. In particular, the mirror may be configured as a beam splitter to provide the beam signal to multiple detector sources.

[0035] The BCD may comprise a focusing element configured to focus and / or defocus the incident beam signal when activated, in particular by increasing and / or decreasing the cross-section of the incident beam at the imaging plane. Overexposure at the sensor may also be mitigated by defocusing the incident beam signal such that the beam intensity is spread over a larger number of capture sites of the sensor. For example, a focused high spot at the sensor may lead to overexposure of a small number of pixels. Defocusing the incident beam signal may expand the area of ​​high intensity components of the beam such that the beam intensity level falls below a threshold that mitigates overexposure. The lens may be configured to adjust the focus of the beam relative to the sensor. The lens may further be configured to completely defocus the beam as an emergency measure such that parts of the incident beam signal that would lead to overexposure do not reach the sensor and / or such parts are defocused to a level such that a safe beam intensity reaches the sensor.

[0036] The BCD may comprise a beam splitter configured to transmit a first portion of the incident beam signal to the imaging plane and a second portion of the incident beam signal towards a second imaging plane when activated, where a surface normal of the imaging plane and a further surface normal of the second imaging plane are angled with respect to each other. The beam splitter may be configured to split the incident beam signal into at least two beam components. Thus, a partial beam having a lower intensity may be generated. The beam splitter may be configured to change an intensity ratio of the at least two split beam components. The beam splitter may be configured to direct at least one of the split beam components towards a sensor. The beam splitter may be used to reduce the intensity of the incident beam signal.

[0037] The BCD may comprise a slit configured to shape the cross-section of the incident beam signal when activated, in particular by partially blocking the incident beam signal. The slit may comprise one or more adjustable apertures. Thus, a portion of the incident beam signal may be blocked. Furthermore, the incident beam signal may be diffracted at the slit.

[0038] The BCD may include a beam chopper configured to modify the beam intensity profile over a time interval when activated. The beam chopper may be configured to periodically block propagation of the beam signal from propagating toward the sensor. The frequency and / or ratio of the blocked to unblocked intervals may be controlled. The beam chopper may be configured as a means to implement pulse width modulation of the beam signal.

[0039] The system may comprise a motion component configured to move the BCD relative to the initial propagation direction of the incident beam signal. This achieves the advantage that the BCD may be positioned such that the effect of the BCD on the exposure of the sensor by the beam signal may be optimized. For example, a beam stop may be positioned to overexpose or block a component of the beam from propagating towards the sensor. The motion component may be included in a control mechanism in which the position of the BCD may be controlled based on the capture signal. The motion component may be configured to move the BCD independently, i.e. without association with a mechanism configured to activate / deactivate the BCD.

[0040] The motion component may be configured to translate and / or rotate the BCD to an active position that enables the BCD to provide a modified beam signal and / or to translate and / or rotate the BCD to an inactive position that disables the BCD from providing a modified beam signal.

[0041] The BCD can receive a control signal and can be activated and / or deactivated based on the control signal. Thus, the BCD can be controlled automatically. Preferably, the control signal can be generated based on user input, but also automatically based on changes in exposure conditions at the sensor and / or general system parameters, i.e. system alignment.

[0042] The BCD can be activated for the duration of an active interval and / or deactivated for the duration of an inactive interval. This achieves the advantage that the BCD can be in a controlled state of activation or deactivation. If there is a deviation from these states, additional safety measures can be triggered. The BCD can have a default state, i.e. an active state to protect the sensors, and deactivation of the BCD can require an active control signal and / or a periodic input to keep the BCD in the deactivated state.

[0043] The control signal may include a control interval having an active interval and / or an inactive interval. A continuous sequence of control intervals may be provided to the BCD to control the state (active / inactive) of the BCD, in particular to control the state continuously. The control interval may include multiple active intervals and multiple inactive intervals.

[0044] The active and inactive intervals may form a periodic signal. This achieves the advantage that a beam signal may be provided to the sensor for a consistent, i.e., at least unchanged, predetermined time interval. The exposure of the sensor may thereby be estimated based on an initial exposure value determination at the start of such predetermined time interval. Preferably, each capture interval of the sensor includes at least one active interval and one inactive interval when the BCD is active.

[0045] The BCD can receive a control parameter and, based on the control parameter, adjust its interaction with the incident beam signal. Based on the control parameter, the BCD can replace any beam intensity modulation by the control signal. The control parameter can indicate that the BCD should not perform any inactive intervals. The control parameter can be used as an emergency measure to protect the sensor.

[0046] The BCD can modify the beam characteristics of the incident beam signal based on the control parameters. The beam characteristics can be any physical characteristic of the beam signal, such as phase, polarization, amplitude, particle velocity distribution, particle energy distribution, particle composition. Preferably, any beam characteristic that contributes to the beam intensity at the sensor can be adjustable by the BCD.

[0047] The BCD can receive a blocking signal and, based on the blocking signal, prevent the incident beam signal from propagating further through the BCD in the initial propagation direction. The blocking signal can replace the control signal. In particular, the blocking signal does not have to be tied to the capture interval. The BCD can be configured to initiate continuous or intermittent blocking of the beam signal based on the blocking signal. Activation of the BCD based on the blocking signal can achieve the advantage that a time delay between an event that triggers the blocking signal and activation of the BCD based on the blocking signal can be minimized. Thus, the time interval during which the sensor is exposed to a potentially harmful beam, i.e., a beam having a harmful intensity pattern, can be advantageously reduced.

[0048] The control signal may include a timing parameter, and the BCD is configured to activate and / or deactivate based on the timing parameter. This may achieve the advantage that activating / deactivating the BCD may be synchronized with other components of the system, in particular with the capture interval, capture rate, and / or shutter frequency of the sensor. Furthermore, the BCD may be configured for timed activation based on the timing parameter, such that relative or absolute timing with respect to the timing specifications of the sensor, e.g. the capture interval, may be achieved. This may achieve the advantage that the ratio of blanking the beam versus exposure of the beam to the sensor may be varied, in particular with reference to the sensor and / or the frame rate of the sensor. The timing parameter may control synchronous or asynchronous operation of the BCD with reference to the sensor.

[0049] The system may comprise a secondary BCD configured to receive an emergency shutoff signal and, based on the emergency shutoff signal, to prevent the incident beam signal from propagating further through the secondary BCD in the initial propagation direction. The secondary BCD may implement further safety measures to protect the sensor, particularly in cases where, based on the BCD, the means to reduce the beam intensity are insufficient or fail to reduce an overexposure or other critical condition at the sensor. The emergency shutoff signal may replace the control signal and / or the shutoff signal to prevent damage to the sensor. The secondary BCD may be configured to move the sensor out of the trajectory of the beam signal, for example to tilt the sensor backwards. Additionally and / or alternatively, the secondary BCD may comprise an electromagnetic, electrostatic or mechanical beam stop configured to stop the propagation of the beam towards the sensor. The secondary BCD may be configured to activate when the BCD fails and / or when the exposure value does not change despite the BCD being activated.

[0050] The secondary BCD may be structurally identical to any of the above-described embodiments of a BCD.

[0051] The secondary BCD can be located upstream or downstream of the BCD with respect to the direction of the incident beam signal. By positioning the secondary BCD upstream of the BCD, sample and / or beam optics, the secondary BCD can also prevent damage to these components when beam intensities outside of the maximum specifications of the respective components and / or sample are detected.

[0052] The system may include a control module configured to provide control and / or shutoff signals to the BCD and / or to provide an emergency shutoff signal to the secondary BCD. The control module may be configured to automatically control the BCD and / or the secondary BCD based on the captured signals provided by the sensors.

[0053] The control module can generate an exposure value based on the capture signal and modify the control signal, in particular the control interval, based on the exposure value. This achieves the advantage that the control module can evaluate the exposure of the sensor and / or determine degradation of the sensor based on the captured beam signal. The control module can in particular adjust the control signal to reduce degradation while providing the captured signal with a maximized dynamic range, resolution and / or signal-to-noise ratio. In particular, captured signal artifacts caused by high beam intensities can be mitigated. The exposure value can represent a measure of exposure of the entire detector area of ​​the sensor and can serve as an indicator of overexposure. The exposure value can also be based on a subsection of the sensor, in particular the subsection that includes the highest brightness level of the respective captured signal.

[0054] The control module can decrease the active interval while the exposure value does not exceed an upper threshold, in particular a maximum safe exposure value. This achieves the advantage that the exposure interval per capture interval of the sensor to the beam signal can be increased while the sensor operates within a safe beam intensity level. In particular, the exposure value can be determined such that no area of ​​the sensor is subjected to harmful overexposure. The control module can start with a maximum active interval with a minimum exposure interval and decrease the active interval for each subsequent frame until the set exposure value is reached and / or until the sensor can be exposed to the beam for the entire capture interval, i.e., the BCD is inactive for the entire duration of the capture interval and the exposure value is below the maximum safe exposure value.

[0055] The control module can increase the active interval and / or decrease the inactive interval when the exposure value exceeds an upper threshold and / or decrease the active interval and / or increase the inactive interval when the exposure value falls below a lower threshold, in particular a minimum detectable exposure value. Thus, the control module can automatically control the exposure of the sensor to an optimal value by activating or deactivating the BCD. Preferably, the BCD does not affect the representation of the beam signal by the captured signal other than reducing the beam intensity and thereby the brightness captured by the sensor. The upper threshold can be based on the physical limitations of the sensor and / or a predetermined lifetime expectancy of the sensor that can be scaled according to the beam intensity to which the sensor is exposed.

[0056] The control module can adjust the control interval such that it includes active intervals during which the BCD is active and inactive intervals during which the BCD is inactive, the control module being configured to modify the ratio of active to inactive intervals based on the exposure value. This achieves the advantage that the control module can also vary the number of active and inactive intervals during the capture interval. Thus, the beam exposure to the sensor can be spread throughout the capture interval, concentrated at the beginning of the capture interval, or concentrated at the end of the capture interval.

[0057] The control module can increase each active interval when the exposure value exceeds an upper threshold and / or decrease each active interval when the exposure value falls below a lower threshold. The set limit can be different from a maximum safe exposure value or a lower detection limit value. Thus, the control module can compensate for varying beam intensity so that the capture signal can contain comparable brightness. In other words, the control module can operate the BCD so that an automatic exposure having a substantially constant brightness value can be achieved. The active intervals can form a set of intervals, each having a specific length. The control module can then uniformly increase or decrease each active interval, for example, so that the frequency of active intervals within a capture interval remains constant.

[0058] The control module can decrease each inactive interval when the exposure value exceeds an upper threshold and / or increase each inactive interval when the exposure value falls below a lower threshold. Similar to controlling the active intervals, the control module can vary the length of the inactive intervals based on the exposure value.

[0059] The control module can adjust the interval durations of the active intervals and the further interval durations of the inactive intervals such that the interval frequency remains constant. Alternatively, the interval pattern can remain constant. For example, a particular sequence of active and inactive intervals can be adjusted such that the relative lengths of the intervals within the sequence remain the same with respect to one another.

[0060] The control module may provide the control signal to the BCD continuously or may provide the control signal to the BCD when the control signal changes.

[0061] The control module can control the interval frequency based on the exposure value to match the exposure value to a predetermined base exposure value. This can achieve the advantage that the captured signal can include a predetermined contrast and / or brightness, thus increasing the level of detail perceivable by the operator. In particular, a visual representation of the captured signal can more clearly show the beam signal characteristics. The predetermined exposure value can also be based on the sensor specifications, such that the predetermined base exposure value reduces the risk of damaging the sensor or increases the chance of extending the sensor's life.

[0062] The control module can adjust the control interval based on the capture frequency of the sensor, which can achieve the advantage that the capture frequency can be synchronized with the control interval to reduce or eliminate interference between the capture frequency and the active interval frequency that can produce uneven exposure of subsequent capture intervals, e.g., perceptible flicker.

[0063] The control module can modify the interval duration of the active interval and / or the further interval duration of the inactive interval at a frequency equal to or less than the acquisition frequency. This can achieve the advantage that the interval duration cannot change within a single acquisition interval. Preferably, the modification of the interval duration occurs at an integer multiple of the acquisition frequency and / or preferably at the joint of two acquisition intervals and / or between two acquisition intervals.

[0064] The control module can enter the limit mode when the exposure value exceeds a predefined limit threshold. Within the limit mode, the beam signal can still be captured by the sensor so that a capture signal can be provided to analyze the beam signal. When switching to the limit mode from a previous mode, for example a normal operating mode, the active interval can be increased. The predefined limit threshold can be lower than the maximum safe exposure value so that it remains possible to provide a capture signal, since the control interval can still include an inactive interval. The limit mode can be a preventative active measure to ensure protection of the sensor. The limit mode can be a reactive mode and can be advantageous when the exposure value gradient is too high such that the maximum safe exposure value may be exceeded within the capture interval. Such a capture interval may already damage the sensor. As a result, the limit mode can represent an additional safety measure in conjunction with the evaluation mode.

[0065] The control module uses pulse width modulation (PWM). Pulse width modulation (PWM) can be applied to the control interval to control the average beam intensity of the modified beam signal during the control interval. PWM can be used to vary the sequence of active and inactive intervals, particularly within the acquisition interval. Each acquisition interval sums the number of intervals during which the beam signal is exposed to the sensor. The PWM base frequency can be higher than the acquisition frequency, and is preferably at least twice the acquisition frequency. PWM can achieve the advantage of decoupling the exposure value from the acquisition interval length. PWM can be controlled such that the type of BCD is taken into account to eliminate or at least minimize beam signal distortion due to BCD. Average beam intensity can be defined as the total beam intensity to which the sensor is exposed during a single acquisition interval.

[0066] The control module can adjust the PWM of the control interval to control, in particular, the averaged beam intensity to achieve a predetermined exposure value, in particular a maximum safe exposure value. This can achieve the advantage of capturing the beam signal such that the captured signal contains a representation of the beam signal spread across multiple brightness levels. In particular, the highest intensity region can be mapped to the highest brightness level, i.e., the maximum safe exposure value, such that the dynamic range for capturing the beam signal can be maximized.

[0067] The control module may apply a duty cycle limiting control to the control interval to limit the beam intensity during an interval of capture of the beam signal by the sensor. The capture interval may be defined based on the sensor. The sensor may be configured to obtain multiple capture intervals within a single readout of the sensor. The number of capture intervals available in a single readout may depend on the exposure value. The duty cycle may be an active interval when the BCD is active. Thus, increasing the duty cycle may decrease the beam intensity, respectively the exposure value.

[0068] The control module may in particular control the beam intensity and adjust the duty cycle of the control intervals to achieve a predetermined exposure value, in particular a maximum safe exposure value.

[0069] The control module can input the evaluation based on a trigger signal. The evaluation mode can be defined as a mode in which a maximum beam intensity is determined while reducing the risk of damaging the sensor. The evaluation mode can be triggered based on a change in the detected beam intensity. In particular, the control module can be configured to trigger the evaluation mode based on an increase in beam intensity, an increase in beam intensity gradient over time, an increase in the spatial gradient of the beam intensity (i.e., the beam is focused on the sensor), an increase in the variation of the beam intensity (i.e., the beam intensity becomes unstable), a shift in the captured beam pattern (e.g., based on a disturbance to the system), and / or an ambient disturbance to the system (e.g., a change in temperature, humidity, pressure, vibration level). The evaluation mode can also be triggered manually, periodically, or as a maintenance measure. The control module can receive a trigger signal. The evaluation mode can precede any normal operating mode of the system. The evaluation mode can also be active while capturing the beam signal.

[0070] The first exposure interval can be, for example, 1 / 250s, with a beam exposure of 10ms. If the exposure is OK, the exposure time can be doubled until a full exposure is reached. During each iteration, the capture signal can be checked for overexposure. When overexposure is detected, the evaluation mode can be aborted and the BCD can remain active.

[0071] At exposure times below the artifact threshold, the image may contain artifacts due to BCD activation and / or deactivation. These artifacts may not be relevant to the detection of overexposure. The artifacts may be advantageous because they may smear the beam signal and make it easier to detect. In particular, localized (e.g., within a pixel) overexposure may be below the detection threshold and thus may not be identified as overexposure, but may still cause sensor damage.

[0072] The exposure time of the sample and the exposure of the sensor can be equal. Compared to other imaging modes, diffraction imaging can be performed with a reduced beam intensity to observe the diffraction pattern. This can be due to the non-uniform distribution of electrons compared to other imaging techniques. It can therefore be advantageous to decouple the exposure time of the sample from the capture interval of the sensor. Thereby, the sample can be protected, especially during orientation, and also to limit the number of electrons hitting the sensor.

[0073] The control module can set a control interval, including a predefined maximum active interval and / or including a minimum inactive interval. The maximum active interval can meet the capture interval. The minimum inactive interval can be zero in length. The limit can be set according to the determined exposure value. Thus, preferably, the beam signal can still be captured at the maximum active interval, i.e. the capture signal includes a representation of the beam signal. The maximum active interval can provide a maximum value of possible beam intensity increase that can still be captured by the sensor without exceeding a maximum safe exposure value.

[0074] The control module can incrementally increase the inactive intervals per capture interval and / or incrementally decrease the active intervals per capture interval, particularly during a series of subsequent capture intervals. This achieves the advantage that the initial capture interval can be based on a beam signal having an initial beam intensity. The initial beam intensity is preferably less than the maximum beam intensity that the sensor can capture without significant degradation or damage. The initial beam intensity can be high enough so that the beam signal can be registered in the capture signal, i.e., the beam intensity is above the detection threshold of the sensor. The control module can determine an exposure value difference between subsequent capture intervals and base the increase rate on the exposure value difference. This can achieve the advantage that the number of capture intervals in the evaluation mode required to determine whether the current beam intensity is within a predetermined parameter, i.e., whether the beam intensity is low enough to allow full exposure of the beam to the sensor during the capture interval, can be minimized. The incremental increase of the inactive interval can be based on the increase rate of the exposure value of the captured interval, so that the number of incremental increases to reach the target interval ratio or exposure value can be reduced.

[0075] The control module can apply PWM to the control intervals to limit the exposure value and incrementally increase the number of active intervals and / or the duration of the active intervals per capture interval. The incremental increase in the number of active intervals can achieve a gradual reduction in the exposure value. Thus, the exposure value can be kept constant with increasing beam intensity. Furthermore, PWM can be applied to control interval sections that do not include any active intervals. Thereby, the remaining structure of the inactive and active intervals can be kept constant, and the inactive interval sections are modulated by PWM. Alternatively or additionally to increasing the number of active intervals, the length of the active intervals can also be increased. The exposure value can also be controlled such that an exposure value gradient over a successive set of capture intervals can be achieved. The active interval pattern can be adjusted according to device parameters of the BCD. In particular, based on switching time, wear per switch (i.e., average time before error), switch delay (i.e., time taken to switch from active to inactive and / or vice versa), trigger delay (i.e., start of switching after switch is indicated by control signal), and / or intensity gradient during switching operation (i.e., rate at which beam intensity at the sensor can be reduced), the lifetime of the BCD and / or sensor can be increased and / or the switching cycle can be optimized.

[0076] The control module can reference the previous capture interval to determine the increase in exposure value per capture interval, which can serve as a basis for determining the increased exposure value for the next capture interval. Additionally, the exposure value gradient over a set of capture intervals can provide an estimate as to when the maximum safe exposure value will be reached or exceeded (i.e., taking into account the planned capture intervals, determine the number of capture intervals when the exposure value is equal to or greater than the maximum safe exposure value).

[0077] The control module can exit the evaluation mode when the difference between the current exposure value and the maximum safe exposure value is smaller than the predicted increase in the exposure value in the subsequent capture interval. This achieves the advantage that overexposure, i.e., exceeding the maximum safe exposure value or a set exposure value below the maximum safe exposure value, can be avoided. This can contribute to a longer life of the sensor. Exiting the evaluation mode can be defined as keeping the exposure value and / or the control interval constant for the subsequent capture interval. When exiting the evaluation mode, the system can return to a normal capture mode with set parameters. The set parameters can be adjusted according to the exposure value determined in the evaluation mode. For example, the time interval during which the beam signal is exposed to the sensor can be shorter than the set time interval to protect the sensor.

[0078] The control module can terminate the evaluation mode when the determined exposure value falls below a maximum safe exposure value and / or when the control interval includes a predefined ratio of active intervals to inactive intervals, preferably when the control interval includes only inactive intervals. This can achieve the advantage that the capture of the beam signal can be achieved without interruption of the beam signal by the BCD. Alternatively, advantageous optical properties, i.e. interval patterns with minimal distortion, minimal imaging artifacts, especially with respect to the sensor properties, can be achieved and / or maintained.

[0079] The control module is configured to maintain the control signal at a control interval that includes a pattern of active and inactive intervals that correspond to the last exposure value determined in the evaluation mode. This can achieve the advantage that the evaluation mode can be used to determine a specific control interval that corresponds to a predetermined exposure value. Preferably, the evaluation mode can be automatically triggered so that a setting change that may result in an exposure value change and / or that may cause overexposure is verified to be safe, i.e. not to result in an exposure value above an exposure value threshold, before being fully implemented. In particular, the evaluation mode can be configured so that each setting change is implemented as quickly as possible while still adhering to safety standards by setting a predetermined parameter starting from a safe parameter start value. From that parameter start value, a gradient can be applied to reach a predetermined parameter while monitoring the capture signal and / or to avoid exposing the sensor to beam signals outside the sensor's set specifications or wear parameters, thereby increasing wear on the sensor.

[0080] The control module is configured to control the exposure value of the subsequent capture interval, preferably the multiple subsequent capture intervals, to the exposure value determined in the evaluation mode, in particular the exposure value last determined in the evaluation mode. This can achieve the advantage of implementing an automatic exposure mode, where the exposure value can be controlled, for example, to be constant, to increase according to a predefined gradient, or to be within a specified exposure value range. Controlling the exposure value can include setting the determined control interval for each subsequent capture interval, in particular until the evaluation mode is re-entered. The control interval can preferably only be changed during the evaluation mode, such that an exposure within device safety limits can be achieved.

[0081] The control module can adjust the active interval pattern while maintaining the last exposure value determined in the evaluation mode. This can achieve the advantage of adjusting the pattern of active and inactive intervals such that BCD switching is minimized and / or a predetermined switching interval is maintained. In particular, the control intervals can be adjusted such that each inactive interval is shorter than a maximum inactive interval and / or each active interval is shorter than a maximum active interval.

[0082] The control module can convert the PWM active interval pattern into consecutive active intervals per capture interval. Multiple active intervals can be grouped to form a single cohesive active interval that can reduce wear on the BCD and / or improve the quality of the capture signal. Each consecutive active interval can be limited to a single capture interval. The PWM mode can be limited to an evaluation mode such that the interval frequency of the active and inactive intervals is lower when the evaluation mode is not active. The summed interval ratio of the active and inactive intervals can remain constant. The resolution of the active and / or inactive interval lengths can at least match the PWM frequency resolution. Thus, the exposure time achieved by a set of PWM modulated active intervals and the respective inactive intervals can match the exposure time achieved by a single consecutive active period within one capture interval, the respective inactive intervals.

[0083] The control module can set an attenuation parameter to control the intensity of the modified beam signal. A BCD configured to adjust the beam signal intensity in a stepwise or continuous manner can be controlled by setting an attenuation parameter. The attenuation parameter can correspond to a particular transmission achieved by the BCD. Thus, the BCD can partially absorb and / or deflect and partially transmit the beam signal. The attenuation of the beam signal can be used in conjunction with adjusting the control interval, particularly using PWM. Additionally and / or alternatively, the BCD can be configured to use PWM to achieve an averaged intensity corresponding to the attenuation parameter.

[0084] The control module can increase the beam intensity per capture interval and determine an exposure value for each increment. The increase in beam intensity can be achieved by adjusting the control interval. The exposure value can be tracked such that the control module can perform an evaluation of the most recent increment against predefined parameters and either terminate the evaluation mode based on the determined exposure value or continue the evaluation mode by implementing a further increment.

[0085] The control module can decrease the active interval such that the beam intensity and / or exposure value is increased by a fixed amount per capture interval. The fixed increase can achieve the advantage of efficiently setting parameters for the next capture interval. The beam intensity and / or exposure value can be non-linearly proportional to the time interval of the exposure, i.e., the active interval, respectively the inactive interval. The fixed amount can be a predetermined absolute value or a predetermined percentage. Increasing by a fixed amount per capture interval can reduce the calculation time required to set parameters for the subsequent capture interval, thus reducing the minimum capture interval length and / or reducing the overall time required to complete the evaluation mode.

[0086] The control module can decrease the active interval such that the beam intensity and / or exposure value is increased per acquisition interval according to a predefined relationship, in particular by a fixed factor. The control module can implement a certain type of scaling, i.e. linear, squared, exponential or logarithmic, to set the relationship of the active intervals of the subsequent acquisition intervals. The scaling can affect the time interval during which the predefined exposure value can be reached. Thus, the scaling can reduce the overall time interval spent in the evaluation mode. Reducing the duration of the evaluation mode can increase the performance of the system, since a higher throughput of non-evaluation mode acquisition intervals can be achieved. Furthermore, the delay caused by the evaluation mode to determine whether the set parameters have achieved a safe exposure value can be reduced. Preferably, the time spent in the evaluation mode is below a predefined threshold so that the efficiency impact on the imaging sequence can be reduced. The control module can reduce the set increase so as not to exceed the maximum safe exposure value.

[0087] The control module can predict a first exposure value for a subsequent capture interval based on the exposure value of the previous capture interval and set a control interval for the subsequent capture interval based on the first exposure value. Furthermore, the set of previous capture intervals can be used to extrapolate the exposure value to estimate the total interval length of the active and / or inactive intervals. Thus, based on a selected slope of the exposure value for the set of capture intervals, the control module can determine when the predetermined exposure value can be reached. Here, a time interval and / or a number of capture intervals can be estimated. This can provide an indication as to when the evaluation mode can end.

[0088] The control module can predict a second exposure value for a further capture interval following a subsequent capture interval based on the exposure value of the previous capture interval, set a control interval for the subsequent capture interval, and / or set a further control interval for the further capture interval, and / or determine whether the second exposure value is less than or equal to the maximum safe exposure value. This achieves the advantage that the prediction of the exposure value can be performed for at least two subsequent capture intervals, increasing the computational efficiency of the control module. The prediction can be increased for a number of subsequent capture intervals, in particular based on a confidence value for the prediction. Predicting the exposure value with reference to the maximum safe exposure value can achieve the advantage that an actual exposure value captured in a subsequent frame that is still within a margin of error for the prediction may still be below the maximum safe exposure value.

[0089] The control module may be configured to predict an exposure value for a selected capture interval of a subsequent sequence of capture intervals based on the exposure value of a previous capture interval. The subsequent sequence of capture intervals may include an increasing sequence of inactive intervals, i.e., the expected exposure value increases incrementally for each capture interval. The selected capture interval may be any capture interval in the sequence. Thus, the difference in number between the subsequent capture interval and the selected capture interval may represent the number of increments that are skipped when the control interval of the subsequent capture interval is set to the control interval of the selected capture interval. Setting the control interval may include setting an equivalent ratio of inactive intervals to active intervals, i.e., the pattern may be the same or different, as long as the total exposure time within the capture interval remains constant. Thus, the PWM scheme may be changed when setting the control interval.

[0090] The control module may determine whether the exposure value is less than or equal to a maximum safe exposure value and / or set the control interval of the subsequent capture interval based on the control interval of the selected capture interval. Preferably, the previous steps are performed when the exposure value is determined to be safe, i.e., within a safe exposure limit below the maximum exposure value, respectively. Setting the subsequent capture interval based on the control interval of the selected capture interval may be defined as setting the subsequent capture interval to the control interval of the selected capture interval.

[0091] The selected capture interval may be in the second position or higher in the sequence of the subsequent capture intervals, so that the selected capture interval represents at least one next element in the sequence, but not the subsequent capture interval, such that at least one increment, i.e., one capture interval, is skipped.

[0092] The control module can set the control interval for the subsequent capture interval based on the further capture interval, in particular preferably to replace the subsequent capture interval with the further capture interval when the second exposure value is equal to or less than the maximum safe exposure value or falls below the maximum safe exposure value by a predetermined margin value. This achieves the advantage that the control module can be configured to skip control intervals to reduce the time or number of capture intervals that would take to reach a predetermined exposure setting. For example, when the exposure value determined for the first set of capture intervals indicates that the entire set of capture intervals in the evaluation mode will not exceed the maximum safety parameter, a predetermined number of capture intervals with lower exposure than the setting to be achieved can be skipped. For this reason, the evaluation mode can be terminated earlier. In other words, the number of capture intervals with reduced beam intensity by the BCD can be reduced to more efficiently evaluate whether the current setting is safe to expose the beam to the sensor without the active interval of the BCD or without the additional active interval.

[0093] The control interval of the capture interval may include a first PWM duty cycle, and the control interval of the subsequent capture interval may include a second PWM duty cycle. The second PWM duty cycle may be higher than the first PWM duty cycle, and preferably higher than the preset PWM duty cycle increase. This achieves the advantage that the control module may skip steps in a predetermined sequence of capture intervals with an assigned preset PWM duty cycle value. Thus, when it is determined that a higher duty cycle value is within the predetermined exposure value limit, the duty cycle of the subsequent frame may be increased such that a portion of the predetermined sequence of duty cycles to be captured is skipped. For example, the sequence of capture intervals may be set to increase the duty cycle by a factor of 5. In conjunction with a determination that a 50% duty cycle is within the safe exposure limit, for an exposure at a duty cycle of 2%, the control module may set the duty cycle for the subsequent capture interval to 50%.

[0094] The control module can predict the exposure value for each capture interval in a capture sequence including a series of subsequent capture intervals. Thereby, the control module can estimate when the maximum safe exposure value will be reached. This can also be achieved outside the evaluation mode to detect a stepwise increase in the exposure value and enter the evaluation mode based on the detected increase. Preferably, the control module can predict the exposure value continuously over a predetermined number of subsequent capture intervals. Thus, exceeding the maximum safe exposure value can be anticipated and the BCD can be activated before actually capturing a capture interval that exceeds the maximum safe exposure value. This can further achieve the advantage that the delay in activating the BCD can be reduced so that a beam signal having an intensity above the beam intensity threshold does not reach the sensor.

[0095] The total activation time, which corresponds to the sum of the durations of the active intervals per capture interval, may decrease for successive capture intervals in a capture sequence. As the activation interval decreases, the beam intensity at the sensor may increase. The time interval during which the BCD is active decreases, and the exposure time per capture interval increases.

[0096] The control module can set a first total activation time for a first capture interval of a capture sequence to a second total activation time for a second capture interval of a capture sequence. Thus, skipping ahead in a sequence of set exposure times can also be implemented while modulating active and inactive intervals using PWM. The control module can decrease the total activation time while maintaining a scaled form of the implemented PWM pattern. For example, the interval frequency of the active intervals can be kept constant while adjusting the interval length of each active interval, each inactive interval within the control interval.

[0097] The second total activation time can be shorter than the first total activation time such that the first exposure value corresponding to the first total activation time is lower than the second exposure value corresponding to the second total activation time. Thus, the exposure value can be increased in the sequence. The control module can achieve control of the beam intensity at the sensor by testing the partial beam signals, i.e., the signals blocked by the BCD during a certain active interval during the capture interval. Thus, a change in the exposure value can trigger an evaluation mode so that the exposure value change is not initially captured during the full capture interval of the current setting, respectively the full control interval. The control interval can be adjusted to include a maximum active interval in order to limit the exposure of the beam signal to the sensor when the beam intensity changes. The total activation time can be summed over the active intervals of a set of PWM sequences.

[0098] The absolute difference between the first total activation time and the second total activation time can be less than the absolute difference between the total activation times of at least one pair of subsequent capture intervals of the capture sequence. The slope of the total activation time over the set of capture intervals can increase linearly, i.e. the difference can be constant, or can increase non-linearly, i.e. the difference can decrease for the set of subsequent capture intervals. Alternatively, the total activation time can be increased, particularly to counter increases in beam intensity. The slope of the total activation time over the set of capture intervals can be adjusted based on exposure values ​​of past capture intervals and / or based on predicted exposure values ​​of subsequent capture intervals.

[0099] The absolute difference between the first total activation time and the second total activation time can be less than the absolute difference between the total activation times of two selected capture intervals of the capture sequence. Thus, the difference in activation time can be determined based on a predetermined set of capture intervals. The capture intervals do not have to be adjacent in the series of capture intervals. The total activation time can span multiple capture intervals.

[0100] The control module may reduce the total activation time of a capture interval by an amount equal to the combined reduction in the total activation time of at least two subsequent capture intervals of the capture sequence, particularly when the reduction results in a predicted exposure value below a maximum safe exposure value. The total activation time may be independent of the number of active intervals and / or the number of inactive intervals within the capture interval and / or the control interval.

[0101] The control module can adjust the predicted exposure value of a capture interval of a capture sequence based on the determined exposure values ​​of the capture intervals of the capture sequence, in particular of previous capture intervals. This can achieve the advantage that the prediction of the exposure value for a subsequent frame can be adjusted based on the exposure values ​​of past capture intervals. Thus, the accuracy of the predicted exposure value can be increased. The adjustment frequency of the predicted exposure value can be based on the predicted exposure value gradient for a set of subsequent capture intervals. In particular, exposure values ​​exceeding a gradient threshold can cause more frequent adjustment of the exposure value prediction to increase accuracy.

[0102] The control module can adjust the decrease rate of the total activation time per capture interval in the capture sequence. This can increase efficiency and / or increase protection of the sensor. In particular, when the beam signal includes beam intensities with a beam intensity variance below a variance threshold, i.e., when the beam intensity does not change significantly between capture intervals, the decrease rate can be increased to reach the preset exposure parameters within a shorter time span, e.g., within a reduced number of capture intervals. Alternatively, when the beam signal includes beam intensities with a beam intensity variance above a variance threshold, i.e., when the beam intensity changes significantly between capture intervals, the decrease rate can be decreased to capture the beam signal over multiple frames without a significant decrease in the total activation time, allowing a more detailed assessment of the beam signal without the risk of damaging the sensor.

[0103] The control module can divide the capture signal into a set of section signals, each section signal comprising a cohesive subset of the capture signal, and determine a section exposure value for each section signal. The section signals can be spatial subsections of the capture signal, i.e. cohesive sets of adjacent pixels, preferably square or at least rectangular sections of the capture signal. Each section signal can be checked individually for overexposure. The grid size can be adjusted based on the beam signal. In particular, the size of the section signals can be correlated to an expected size of the overexposed region and adjusted accordingly. Preferably, the size of the section signals is larger than the expected size of the overexposed region.

[0104] The control module can overlap the aggregated subsets of the captured signals that define the section signals along at least one dimension of the beam signal, preferably by spatially overlapping the aggregated subsets by at least 25%, more preferably by spatially overlapping the aggregated subsets by at least 50%. This can achieve the advantage that the overexposed area can be evaluated in its entirety, i.e. the exposure value can reflect the actual exposure of the aggregated area, e.g. the bright spot. By overlapping the areas, the probability of capturing the entire bright spot in one section signal can be increased. The possibility that the bright spot is split into several section signals and thus does not exceed the exposure value threshold can be reduced. In other words, the chance that a local beam intensity maximum, which can potentially damage the sensor or reduce the sensor's lifespan, can be split into several areas and therefore not detected can be reduced.

[0105] The control module can activate the BCD and / or enter an evaluation mode when a section exposure value for a signal section exceeds a maximum section exposure value. Thus, local overexposure can trigger a protective measure to reduce the beam intensity at the sensor. The exposure value can be based on the section exposure value or multiple section exposure values. Each section exposure value can be weighted based on the relative position of the respective section signal in the captured signal. For example, higher weights can be assigned to regions of expected high beam intensity and / or regions with a high probability of being exposed to high beam intensity. In particular, regions that are expected to capture at least a portion of the beam signal capturing the diffraction pattern can be assigned a higher weight compared to regions with a low probability of capturing a portion of the diffraction pattern.

[0106] The control module can filter the capture signal to generate a filtered capture signal. Filtering the capture signal can reduce the probability of generating a false positive when determining whether an exposure value threshold has been exceeded. A spatial filter can be applied by the control module to spread the beam intensity peak across multiple detector sites, e.g., pixels, of the sensor to increase sensitivity to overexposure and / or distinguish actual overexposure from defects in the sensor, e.g., hot pixels, etc.

[0107] The control module can apply a filter to each section signal, in particular applying the filtering to all section signals in parallel to generate a filtered section signal. Each section signal can, for example, cover a square area of ​​the capture signal, in particular having an edge length based on a multiple of two, for example a 64x64 pixel area. The filtered signal can be based on a dark-corrected difference frame, which can be the difference of two capture signals without a beam signal hitting the sensor. The section signals can be as small as 5x5 pixels. The control module can be configured to distinguish overexposure from sensor defects, i.e. to distinguish between sensor offsets, radiation damage, defective pixels and / or defective pixel clusters. Applying a filter can further provide the advantage of detecting spot-like or stripe-like high beam intensity areas. Alternatively and / or additionally, the control module can be configured to detect beam intensity peaks, respectively exposure value peaks, based on the capture signal. In particular, a peak detection method can be implemented and the exposure value can be based on the result of the peak detection method. By applying a filter, the shape of the peaks can be changed to increase the likelihood that they are detected as beam intensity peaks and / or overexposed areas.

[0108] The control module can determine an exposure value based on the filtered section signal, which achieves the advantage that the application of the filter, in particular in conjunction with taking into account at least one section, increases the sensitivity of the control module to record overexposure and preferably controls the BCD accordingly to limit the beam intensity.

[0109] The control module can spatially filter the captured signal to reduce spatial intensity gradients, in particular to smooth the intensity values. This can achieve the advantage of distinguishing intensity peaks caused by the beam signal from sensor defects and / or signal artifacts. The reduction of spatial intensity gradients can be achieved, for example, by spreading high intensity peaks over multiple pixels.

[0110] The control module can receive a target acquisition interval, the target acquisition interval not including any active intervals, and / or the control module is further configured to determine a maximum allowable beam intensity value and / or a maximum exposure value with reference to the target acquisition interval. The allowable beam intensity can be scaled based on the acquisition interval. For example, the allowable beam intensity can be inversely proportional to the acquisition interval length. The exposure can be controlled by either the BCD or the acquisition interval length. The beam signal can include a non-stationary beam intensity pattern such that motion blur can be controlled by either the interval length of the inactive interval and / or the interval length of the acquisition interval. The control module can adjust the acquisition based on the target acquisition interval and / or adjust the control interval based on the target acquisition interval. The target acquisition interval can be achieved by adjusting the inactive interval and the active interval such that the sum of the inactive interval and / or the inactive interval corresponds to the target acquisition interval.

[0111] The control module can incrementally increase the inactive intervals per capture interval of the capture sequence and / or incrementally decrease the active intervals per capture interval of the capture sequence, and / or determine an exposure value for at least one capture interval of the capture sequence or each capture interval of the capture sequence, and / or set a control interval that includes only inactive intervals that do not include active intervals, based on at least one exposure value of the capture interval of the capture sequence. Thus, the control module can determine whether a further test capture interval with increased beam intensity should be captured to determine the actual beam intensity with reference to the acceptable parameters of the system. Based on the exposure value, the control module can determine whether a subsequent exposure without activation of the BCD will result in overexposure of the sensor. When the exposure is controlled by the active interval and not by the capture interval, the target can keep a predetermined portion of the capture interval free of active intervals.

[0112] The control module can match the maximum safe exposure value to the maximum safe capture interval. In particular, local maxima in beam intensity can generate local overexposure in the capture signal. The capture interval and / or the sum of the inactivity intervals can be limited to not exceed a threshold value so that the sensor is not overexposed.

[0113] The control module can determine an optimal safe capture interval. The optimal safe capture interval can also be an optimal safe ratio of active interval to inactive interval within a particular capture interval. The optimal safe capture interval can be determined based on the captured beam intensity and / or based on the corresponding exposure value. The optimal safe capture interval can be defined by maximizing the dynamic range of the representation of the beam signal by the capture signal, maximizing the sensor lifetime, and / or reducing the captured beam intensity according to a predetermined requirement. To capture a diffraction pattern, the spatial distribution of the beam intensity peaks may be more relevant than the intensity distribution. For this reason, the control module may prioritize capturing each peak while reducing the brightness resolution, i.e., the dynamic range, and then limit the captured beam intensity to increase the sensor lifetime.

[0114] The control module can determine a minimum exposure value and set a control interval based on the minimum exposure value such that the beam signal is captured and registered within the captured signal above the noise floor of the sensor and / or such that the potential increase in exposure value to the maximum safe exposure value is maximized. At the minimum exposure value, the headroom for capturing intensity increases can be maximized. The control module can determine the minimum exposure value within the evaluation mode or as a separate step or mode. The minimum exposure value can be linked to the minimum activation and deactivation timing of the BCD, i.e., the minimum length of the inactive interval achievable by the BCD. The evaluation mode can start with the minimum exposure value and / or the minimum active interval of the BCD.

[0115] The sensor may acquire the beam signal at an acquisition rate above a minimum acquisition rate threshold, particularly to provide a flicker-free, continuously updated acquisition signal.

[0116] The capture rate can be decoupled from the beam exposure interval defined by the total activation time per capture interval and / or the capture rate is independent of the sequence of active and inactive intervals. The control of the BCD can also be asynchronous with the camera shutter, i.e., the BCD activation pattern can be shifted for a sequence of capture intervals. Alternatively, the active and inactive intervals can form a pattern that allows for consistent exposure without synchronization of the BCD control intervals with the capture intervals. For example, the pattern of active and inactive intervals can have a significantly higher fundamental frequency with the intervals alternating than the capture frequency.

[0117] The control module can adjust the control interval so that the BCD is activated when the capture interval ends and / or when the capture interval begins.

[0118] According to a second aspect, the present invention relates to a method for sensor protection in electronic imaging applications comprising the step of providing a modified beam signal based on an incident beam signal by varying an intensity of the modified beam signal over a predetermined time interval.

[0119] The method may include capturing a beam signal, in particular a modified beam signal and / or an incident beam signal, with a predetermined spatial resolution and / or a variable temporal resolution, and providing a capture signal based on the captured beam signal.

[0120] The method may include ceasing the incident beam signal from propagating through the BCD, and in particular the blanker, in an initial propagation direction of the incident beam signal when the BCD is activated.

[0121] The method may include providing a switchable physical barrier configured to at least partially intersect an initial direction of propagation of the incident beam signal.

[0122] The method may include providing an electrostatic field such that an initial propagation direction of the incident beam signal and a modified propagation direction of the modified beam signal are at an angle with respect to each other by activating an electrostatic shutter.

[0123] The method may include providing an electromagnetic field, in particular a periodic electromagnetic field, such that an initial propagation direction of the incident beam signal and a modified propagation direction of the modified beam signal are at an angle to each other by activating an electromagnetic shutter.

[0124] The method may include adjusting, in particular reducing, the intensity of the incident beam to provide a modified beam having an intensity substantially equal to or lower than the incident beam.

[0125] The method may include blocking at least a portion of a cross-section of the incident beam.

[0126] The method may include, when activated, transforming a cross-section of an incident beam.

[0127] The method may include at least partially reflecting and / or deflecting the incident beam signal.

[0128] The method may include, inter alia, focusing and / or defocusing the incident beam signal by increasing and / or decreasing the cross-section of the incident beam at the imaging plane.

[0129] A method according to any of the above embodiments includes transmitting a first portion of the incident beam signal towards an imaging plane and transmitting a second portion of the incident beam signal towards a second imaging plane, wherein a surface normal of the imaging plane and a further surface normal of the second imaging plane are angled relative to each other.

[0130] The method may include shaping a cross-section of the incident beam signal, particularly by blocking portions of the incident beam signal.

[0131] The method may include modifying a beam intensity profile over a time interval.

[0132] The method can include moving the BCD relative to an initial direction of propagation of the incident beam signal.

[0133] The method according to any of the above embodiments includes translating and / or rotating the BCD to an active position that enables the BCD to provide a modified beam signal, and / or translating and / or rotating the BCD to an inactive position that disables the BCD from providing a modified beam signal.

[0134] The method may include receiving a control signal and activating a BCD based on the control signal.

[0135] The method may include activating the BCD for a duration of an activation time interval.

[0136] The method may include specifying an activation time interval with a control signal.

[0137] The method can include adjusting an interaction of the BCD with the incident beam signal based on the control parameter.

[0138] The method may include modifying beam characteristics of the incident beam signal based on the control parameter.

[0139] The method can include preventing the incident beam signal from propagating further through the BCD in the initial propagation direction based on the blocking signal.

[0140] The method may include activating and / or deactivating the BCD based on the timing parameter.

[0141] The method may include receiving an emergency shutoff signal and, based on the emergency shutoff signal, preventing the incident beam signal from passing through the BCD and further propagating in the initial propagation direction.

[0142] The method may include providing a control signal to a BCD.

[0143] The method may include generating an exposure value based on the captured signal, and modifying the control signals, particularly the control interval, based on the exposure value.

[0144] The method may include increasing the active interval and / or decreasing the inactive interval when the exposure value exceeds an upper threshold, and / or decreasing the active interval and / or increasing the inactive interval when the exposure value falls below a lower threshold.

[0145] The method may include adjusting the control intervals such that the control intervals include active intervals during which the BCD is active and inactive intervals during which the BCD is inactive, and modifying a ratio of active intervals to inactive intervals based on the exposure value.

[0146] The method may include increasing each active interval when the exposure value exceeds an upper threshold and / or decreasing each active interval when the exposure value falls below a lower threshold.

[0147] The method may include decreasing each inactive interval when the exposure value exceeds an upper threshold and / or increasing each inactive interval when the exposure value falls below a lower threshold.

[0148] The method may include adjusting the interval durations of the active intervals and the further interval durations of the inactive intervals such that the interval frequency remains constant.

[0149] The method may include providing the control signal to the BCD continuously or providing the control signal to the BCD when the control signal changes.

[0150] The method may include controlling the interval frequency based on the exposure value to match the exposure value to a predetermined base exposure value.

[0151] The method may include adjusting the control interval based on an acquisition frequency of the sensor.

[0152] The method may include modifying the interval duration of the active interval and / or the further interval duration of the inactive interval at a frequency below the capture frequency.

[0153] The method may include entering a limiting mode when the exposure value exceeds a predetermined limiting threshold.

[0154] The method may include applying pulse width modulation (PWM) to the control interval to control an averaged beam intensity of the modified beam signal during the control interval.

[0155] The method may include adjusting the PWM of the control interval, in particular controlling the averaged beam intensity to achieve a predetermined exposure value, in particular a maximum safe exposure value.

[0156] The method may include applying a duty cycle limiting control to a control interval to limit the beam intensity during an interval of capture of the beam signal by the sensor.

[0157] The method may include adjusting the duty cycle of the control interval, in particular controlling the beam intensity to achieve a predetermined exposure value, in particular a maximum safe exposure value.

[0158] The method may include entering an evaluation mode upon receiving a trigger signal.

[0159] The method may include setting a control interval that includes a predetermined maximum active interval and / or that includes a minimum inactive interval.

[0160] The method according to any of the above embodiments may include incrementally increasing the inactive interval per acquisition interval and / or incrementally decreasing the active interval per acquisition interval, particularly during a subsequent series of acquisition intervals.

[0161] The method may include applying PWM to the control intervals to limit the exposure value and incrementally increase the number of active intervals and / or the duration of the active intervals per capture interval.

[0162] The method may include determining an increase in exposure value per capture interval by reference to a previous capture interval.

[0163] The method may terminate the evaluation mode when the difference between the current exposure value and the maximum safe exposure value is less than the predicted increase in the exposure value in the subsequent capture interval.

[0164] The method may include terminating the evaluation mode when the determined exposure value falls below a maximum safe exposure value and / or when the control interval includes a predetermined ratio of active intervals to inactive intervals, preferably when the control interval includes only inactive intervals.

[0165] The method may include maintaining the control signal at a control interval that includes a pattern of active and inactive intervals that corresponds to the last exposure value determined in the evaluation mode.

[0166] The method may comprise controlling the exposure value of a subsequent capture interval, preferably a number of subsequent capture intervals, to the exposure value determined in the evaluation mode, in particular the exposure value last determined in the evaluation mode.

[0167] The method may include adjusting the active spacing pattern while maintaining the last exposure value determined in the evaluation mode.

[0168] The method may include converting the PWM active interval pattern into consecutive active intervals per capture interval.

[0169] The method may include setting an attenuation parameter to control an intensity of the modified beam signal.

[0170] The method may include increasing the beam intensity per capture interval and determining an exposure value for each increase.

[0171] The method may include decreasing the active interval such that the beam intensity and / or exposure value is increased by a fixed amount per capture interval.

[0172] The method may include decreasing the active interval such that the beam intensity and / or exposure value per capture interval is increased according to a predetermined relationship, in particular by a fixed factor.

[0173] The method may include predicting a first exposure value for a subsequent capture interval based on an exposure value of a previous capture interval, and setting a control interval for the subsequent capture interval based on the first exposure value.

[0174] The method may include predicting a second exposure value for a further capture interval following the subsequent capture interval based on an exposure value of a previous capture interval, setting a control interval for the subsequent capture interval, and / or setting a further control interval for the further capture interval, and / or determining whether the second exposure value is less than or equal to a maximum safe exposure value.

[0175] The method may preferably include setting a control interval for the subsequent capture interval based on the further capture interval, in particular to replace the subsequent capture interval with the further capture interval when the second exposure value is less than or equal to the maximum safe exposure value or falls below the maximum safe exposure value by a predetermined margin value.

[0176] The method may include predicting an exposure value for each capture interval in a capture sequence that includes a series of subsequent capture intervals.

[0177] The method may include decreasing a total activation time, corresponding to a total duration of active intervals per acquisition interval, for successive acquisition intervals in the acquisition sequence.

[0178] The method may include setting a first total activation time for a first capture interval of the capture sequence to a second total activation time of a second capture interval of the capture sequence.

[0179] The method may include reducing a total activation time of a capture interval by an amount equal to a combined reduction in the total activation time of at least two subsequent capture intervals of the capture sequence, particularly when the reduction results in a predicted exposure value that is below a maximum safe exposure value.

[0180] The method may include adjusting a predicted exposure value for a capture interval of a capture sequence based on a determined exposure value of the capture interval, particularly a previous capture interval, of the capture sequence.

[0181] The method may include adjusting a decrease rate of a total activation time per capture interval within a capture sequence.

[0182] The method may include dividing the captured signal into a set of section signals, each section signal comprising a cohesive subset of the captured signal, and determining a section exposure value for each section signal.

[0183] The method may include overlapping coherent subsets of captured signals that define section signals along at least one dimension of the beam signal, preferably spatially overlapping the coherent subsets by at least 25%, more preferably spatially overlapping the coherent subsets by at least 50%.

[0184] The method may include activating a BCD and / or entering an evaluation mode when a section exposure value for a signal section exceeds a maximum section exposure value.

[0185] The method may include filtering the acquired signal to produce a filtered acquired signal.

[0186] The method may include applying a filter to each section signal, in particular applying filtering to all section signals in parallel to generate filtered section signals.

[0187] The method may include determining an exposure value based on the filtered section signal.

[0188] The method may include spatially filtering the captured signal to reduce spatial intensity gradients, in particular to smooth the intensity values.

[0189] The method may include receiving a target acquisition interval, the target acquisition interval not including any active intervals, and / or determining a maximum allowable beam intensity value and / or a maximum exposure value with reference to the target acquisition interval.

[0190] The method may include incrementally increasing an inactive interval per capture interval of the capture sequence, and / or incrementally decreasing an active interval per capture interval of the capture sequence, and / or determining an exposure value for at least one capture interval of the capture sequence or for each capture interval of the capture sequence, and / or setting a control interval that includes only inactive intervals and no active intervals based on the exposure value of at least one capture interval of the capture sequence.

[0191] The method may include matching a maximum safe exposure value to a maximum safe capture interval.

[0192] The method may include determining an optimal safe capture interval.

[0193] The method may include determining a minimum exposure value and setting a control interval based on the minimum exposure value such that a beam signal is captured and registered within a captured signal that is above the noise floor of the sensor and / or such that a potential increase in the exposure value to a maximum safe exposure value is maximized.

[0194] The method may include acquiring the beam signal at an acquisition rate above a minimum acquisition rate threshold, particularly to provide a continuously updated acquisition signal that is free of flicker.

[0195] The method may include adjusting the control interval such that the BCD is activated when the capture interval ends and / or when the capture interval begins.

[0196] The invention is further defined by the following numbered embodiments.

[0197] In the following, system embodiments are discussed. These embodiments are abbreviated by the letter "S" followed by a number. These embodiments are meant whenever reference is made herein to "system embodiments." S1. A system for sensor protection in electronic imaging applications, comprising: A system comprising: a beam control device (BCD) configured to provide a beam signal based on an incident beam signal, the beam signal comprising a modified beam intensity. S2. The system of any preceding embodiment, wherein the BCD is configured to vary the intensity of the beam signal over a predetermined time interval. S3. The system of any preceding embodiment, A system comprising a sensor configured to capture a beam signal, in particular a modified beam signal and / or an incident beam signal, and provide a captured signal based on the beam signal. S4. The system of any preceding embodiment having the features of S3, wherein the sensor is configured to provide a spatially and / or temporally resolved representation of the beam signal as part of the captured signal. A system as described in any of the preceding embodiments, wherein the S5.BCD comprises a blanker configured to stop the incident beam signal from propagating through the blanker in an initial propagation direction of the incident beam signal when activated. S6. A system as described in any of the preceding embodiments, wherein the BCD comprises a mechanical shutter configured to provide a switchable physical barrier when activated, configured to at least partially intersect with an initial propagation direction of the incident beam signal. A system as described in any of the preceding embodiments, wherein the S7.BCD comprises an electrostatic shutter configured to provide an electrostatic field when activated such that, in particular, when the electrostatic shutter is active, an initial propagation direction of the incident beam signal and a modified propagation direction of the modified beam signal are at an angle with respect to each other. S8. A system according to any of the preceding embodiments, wherein the BCD comprises an electromagnetic (electrodynamic) shutter configured to provide an electromagnetic field, in particular a periodic electromagnetic field, such that when activated, in particular when the electromagnetic shutter is active, the initial propagation direction of the incident beam signal and the modified propagation direction of the modified beam signal are at an angle to each other. A system as described in any of the preceding embodiments, comprising an attenuator configured to reduce an intensity of the incident beam when the S9.BCD is activated to provide a modified beam having an intensity substantially equal to or lower than the incident beam signal. A system as described in any of the preceding embodiments, wherein the BCD comprises an aperture configured to block at least a portion of a cross-section of the incident beam signal when activated. S11. A system as in any of the preceding embodiments, wherein the BCD comprises a lens configured to transform a cross-section of the incident beam when activated. A system according to any of the preceding embodiments, wherein the BCD comprises a mirror configured to at least partially reflect and / or deflect the incident beam signal when activated. A system as described in any of the preceding embodiments, wherein the S13.BCD comprises a focusing element configured to focus and / or defocus the incident beam signal when activated, in particular by increasing and / or decreasing the cross-section of the incident beam at the imaging plane. A system as described in any of the preceding embodiments, wherein the S14.BCD comprises a beam splitter configured to transmit a first portion of the incident beam signal to the imaging plane and transmit a second portion of the incident beam signal towards the second imaging plane when activated, wherein a surface normal of the imaging plane and a further surface normal of the second imaging plane are angled with respect to each other. A system as described in any of the preceding embodiments, wherein the BCD comprises a slit configured to shape a cross-section of the incident beam signal when activated, in particular by partially blocking the incident beam signal. A system as described in any of the preceding embodiments, wherein the BCD comprises a beam chopper configured to modify the beam intensity profile over a time interval when activated. S17. The system of any of the preceding embodiments, comprising a motion component configured to move the BCD relative to an initial propagation direction of the incident beam signal. S18. The system of any preceding embodiment having the feature of S17, wherein the motion component is configured to translate and / or rotate the BCD to an active position that enables the BCD to provide a modified beam signal, and / or to translate and / or rotate the BCD to an inactive position that disables the BCD to provide a modified beam signal. A system as in any preceding embodiment, wherein the S19. BCD is configured to receive a control signal and activate and / or deactivate based on the control signal. A system according to any of the preceding embodiments having the features of S19, wherein the BCD is configured to activate for the duration of an active interval and / or to deactivate for the duration of an inactive interval. S21. The system of any preceding embodiment having the features of S20, wherein the control signal comprises a control interval having an active interval and / or an inactive interval. S22. The system of any preceding embodiment having the features of S20, wherein the active and inactive intervals form a periodic signal. A system as described in any of the preceding embodiments, wherein the S23.BCD is configured to receive a control parameter and adjust an interaction with the incident beam signal based on the control parameter. A system according to any of the preceding embodiments having features of S19, wherein the BCD is configured to modify beam characteristics of the incident beam signal based on the control parameters. S25. A system as described in any of the preceding embodiments, wherein the BCD is configured to receive a blocking signal and, based on the blocking signal, prevent the incident beam signal from passing through the BCD and propagating further in the initial propagation direction. S26. The system of any preceding embodiment having the features of S19, wherein the control signal includes a timing parameter, and the BCD is configured to activate and / or deactivate based on the timing parameter. S27. A system as described in any of the preceding embodiments, comprising a secondary BCD configured to receive an emergency shutoff signal and, based on the emergency shutoff signal, prevent the incident beam signal from passing through the secondary BCD and further propagating in the initial propagation direction. S28. The system of any of the preceding embodiments having the features of S27, wherein the secondary BCD is a BCD according to any one of embodiments S5 to S12. S29. The system of any of the preceding embodiments having the features of S27, wherein the secondary BCD is located upstream or downstream of the BCD with respect to the direction of the incident beam signal. S30. The system of any of the preceding embodiments, comprising a control module configured to provide control signals and / or shutdown signals to the BCD and / or provide an emergency shutdown signal to a secondary BCD. S31. A system according to any of the preceding embodiments having features of S3 and S30, wherein the control module is configured to generate an exposure value based on the capture signal, and to modify the control signal, in particular the control interval, based on the exposure value. S32. A system according to any of the preceding embodiments having the features of S31, wherein the control module is configured to decrease the active interval while the exposure value does not exceed an upper threshold, in particular a maximum safe exposure value. S33. A system according to any of the preceding embodiments having the features of S31, wherein the control module is configured to increase the active interval and / or decrease the inactive interval when the exposure value exceeds an upper threshold, and / or to decrease the active interval and / or increase the inactive interval when the exposure value falls below a lower threshold, in particular a minimum detected exposure value. S34. A system as described in any of the preceding embodiments having features of S21 and S31, wherein the control module is configured to adjust the control intervals such that the control intervals include active intervals during which the BCD is active and inactive intervals during which the BCD is inactive, and wherein the control module is configured to modify the ratio of active intervals to inactive intervals based on the exposure value. S35. The system of any preceding embodiment having the feature of S34, wherein the control module is configured to increase each active interval when the exposure value exceeds an upper threshold and / or decrease each active interval when the exposure value falls below a lower threshold. S36. The system of any preceding embodiment having the feature of S34, wherein the control module is configured to decrease each inactive interval when the exposure value exceeds an upper threshold and / or increase each inactive interval when the exposure value falls below a lower threshold. S37. The system of any preceding embodiment having the feature of S34, wherein the control module is configured to adjust the interval durations of the active intervals and the further interval durations of the inactive intervals such that the interval frequency remains constant. S38. The system of any preceding embodiment having the features of S30, wherein the control module is configured to provide the control signal to the BCD continuously or when the control signal changes. S39. The system of any preceding embodiment having the feature of S34, wherein the control module is configured to control the interval frequency based on the exposure value to match the exposure value to a predetermined base exposure value. S40. The system of any of the preceding embodiments having features of S3 and S30, wherein the control module is configured to adjust the control interval based on an acquisition frequency of the sensor. S41. The system of any preceding embodiment having the feature of S40, wherein the control module is configured to modify the interval duration of an active interval and / or the further interval duration of an inactive interval at a frequency less than or equal to the capture frequency. S42. A system as in any preceding embodiment having the features of S31, wherein the control module is configured to enter the limit mode when the exposure value exceeds a predetermined limit threshold. S43. The system of any preceding embodiment having the features of S42, wherein the control module is configured to apply pulse width modulation (PWM) to the control interval to control an average beam intensity of the modified beam signal during the control interval. S44. A system according to any of the preceding embodiments having the features of S43, wherein the control module is configured to adjust the PWM of the control interval, in particular to control the average beam intensity, in order to achieve a predetermined exposure value, in particular a maximum safe exposure value. S45. A system as described in any of the preceding embodiments having the features of S20 and S42, wherein the control module is configured to apply duty cycle limiting control to the control interval to limit the beam intensity during an interval of capture of the beam signal by the sensor. S46. A system according to any of the preceding embodiments having the features of S45, wherein the control module is configured to adjust the duty cycle of the control interval, in particular to control the beam intensity to achieve a predetermined exposure value, in particular a maximum safe exposure value. S47. The system of any preceding embodiment having the features of S31, wherein the control module is configured to enter the evaluation mode when the control module receives a trigger signal. S48. A system as in any preceding embodiment having the feature of S47, wherein the control module is configured to set control intervals including a predetermined maximum active interval and / or including a minimum inactive interval. S49. A system as described in any of the preceding embodiments having the features of S47, wherein the control module is configured to incrementally increase the inactive interval per acquisition interval and / or incrementally decrease the active interval per acquisition interval, particularly during a subsequent series of acquisition intervals. S50. A system as described in any preceding embodiment having the features of S47, wherein the control module is configured to apply PWM to the control intervals to limit the exposure value and to incrementally increase the number of active intervals per capture interval and / or the duration of the active intervals. S51. A system as in any preceding embodiment having the feature of S47, wherein the control module is configured to determine an increase in exposure value per capture interval with reference to a previous capture interval. S52. A system as described in any of the preceding embodiments having the feature of S51, wherein the control module is configured to terminate the evaluation mode when the difference between the current exposure value and the maximum safe exposure value is less than the predicted increase in the exposure value in the subsequent capture interval. S53. A system as described in any of the preceding embodiments having the feature of S51, wherein the control module is configured to terminate the evaluation mode when the determined exposure value falls below a maximum safe exposure value and / or when the control interval comprises a predetermined ratio of active intervals to inactive intervals, preferably when the control interval comprises only inactive intervals. S54. A system as described in any preceding embodiment having the feature of S52, wherein the control module is configured to maintain the control signal at a control interval including a pattern of active and inactive intervals corresponding to the last exposure value determined in the evaluation mode. S55. A system according to any of the preceding embodiments having the features of S52, wherein the control module is configured to control the exposure value of a subsequent capture interval, preferably a number of subsequent capture intervals, to the exposure value determined in the evaluation mode, in particular the exposure value last determined in the evaluation mode. S56. The system of any preceding embodiment having the feature of S55, wherein the control module is configured to adjust the active interval pattern while maintaining the last exposure value determined in the evaluation mode. S57. The system of any preceding embodiment having the feature of S56, wherein the control module is configured to convert the PWM active interval pattern into consecutive active intervals per capture interval. S58. A system as described in any of the preceding embodiments having at least one of features of S9-S13 and S30, wherein the control module is configured to set an attenuation parameter to control the intensity of the modified beam signal. S59. The system of any preceding embodiment having the features of S47 and S58, wherein the control module is configured to increase the beam intensity per capture interval and determine an exposure value for each increase. S60. A system as described in any preceding embodiment having the feature of S47, wherein the control module is configured to decrease the active interval such that the beam intensity and / or exposure value is increased by a fixed amount per capture interval. S61. A system according to any of the preceding embodiments having the features of S47, wherein the control module is configured to decrease the active interval such that the beam intensity and / or exposure value is increased per capture interval according to a predetermined relationship, in particular by a fixed factor. S62. A system as described in any preceding embodiment having the feature of S47, wherein the control module is configured to predict a first exposure value for a subsequent capture interval based on an exposure value of a previous capture interval, and set a control interval for the subsequent capture interval based on the first exposure value. S63. The system of any of the preceding embodiments having the feature of S62, wherein the control module is configured to predict a second exposure value for a further capture interval following the subsequent capture interval based on the exposure value of the previous capture interval, set a control interval for the subsequent capture interval, and / or set a further control interval for the further capture interval, and / or determine whether the second exposure value is less than or equal to a maximum safe exposure value. S64. The system of any of the preceding embodiments, wherein the control module is configured to predict an exposure value for a selected capture interval of a subsequent sequence of capture intervals based on an exposure value of a previous capture interval, determine whether the exposure value is less than or equal to a maximum safe exposure value, and / or set a control interval of the subsequent capture interval based on a control interval of the selected capture interval, wherein the selected capture interval is greater than or equal to a second position of the subsequent sequence of capture intervals. S65. A system according to any of the preceding embodiments having the features of S63, wherein the control module is configured to set a control interval for the subsequent capture interval based on the further capture interval, in particular to replace the subsequent capture interval with the further capture interval when the second exposure value is less than or equal to a maximum safe exposure value or falls below the maximum safe exposure value by a predetermined margin value. S66. The system of any of the preceding embodiments having the features of S65, wherein the control interval of a capture interval includes a first PWM duty cycle and the control interval of a subsequent capture interval includes a second PWM duty cycle, the second PWM duty cycle being higher than the first PWM duty cycle and preferably higher than a preset PWM duty cycle increase. S67. The system of any preceding embodiment having the feature of S47, wherein the control module is configured to predict an exposure value for each capture interval in a capture sequence that includes a series of subsequent capture intervals. S68. The system of any preceding embodiment having the feature of S67, wherein a total activation time, corresponding to a total duration of active intervals per acquisition interval, decreases for successive acquisition intervals in an acquisition sequence. S69. The system of any preceding embodiment having the feature of S67, wherein the control module is configured to set a first total activation time for a first capture interval of the capture sequence to a second total activation time of a second capture interval of the capture sequence. S70. The system of any preceding embodiment having the feature of S69, wherein the second total activation time is less than the first total activation time such that a first exposure value corresponding to the first total activation time is lower than a second exposure value corresponding to the second total activation time. S71. The system of any preceding embodiment having the feature of S70, wherein an absolute difference between the first total activation time and the second total activation time is less than an absolute difference between the total activation times of at least one pair of subsequent capture intervals of the capture sequence. S72. The system of any preceding embodiment having the feature of S70, wherein an absolute difference between the first total activation time and the second total activation time is less than an absolute difference between the total activation times of two selected capture intervals of the capture sequence. S73. A system as described in any of the preceding embodiments having the features of S67, wherein the control module is configured to reduce the total activation time of a capture interval by an amount equal to the combined reduction in the total activation time of at least two subsequent capture intervals of the capture sequence, in particular when the reduction results in a predicted exposure value below a maximum safe exposure value. S74. A system according to any of the preceding embodiments having the features of S47, wherein the control module is configured to adjust a predicted exposure value of a capture interval of a capture sequence based on a determined exposure value of the capture interval of the capture sequence, in particular a previous capture interval. S75. The system of any preceding embodiment having the feature of S47, wherein the control module is configured to adjust a rate of decrease of the total activation time per capture interval within a capture sequence. S76. A system as described in any of the preceding embodiments having features of S3 and S30, wherein the control module is configured to divide the capture signal into a set of section signals, each section signal comprising a cohesive subset of the capture signal, and determine a section exposure value for each section signal. S77. The system of any preceding embodiment having the feature of S76, wherein the control module is configured to overlap coherent subsets of captured signals defining section signals along at least one dimension of the beam signal, preferably to spatially overlap the coherent subsets by at least 25%, more preferably to spatially overlap the coherent subsets by at least 50%. S78. The system of any preceding embodiment having the feature of S77, wherein the control module is configured to activate the BCD and / or enter an evaluation mode when the section exposure value of the signal section exceeds a maximum section exposure value. S79. The system of any of the preceding embodiments having features of S3 and S30, wherein the control module is configured to filter the captured signal to generate a filtered captured signal. S80. A system according to any of the preceding embodiments having features of S76 and S79, wherein the control module is configured to apply a filter to each section signal, in particular to apply filtering to all section signals in parallel to generate filtered section signals. S81. The system of any of the preceding embodiments having the features of S80, wherein the control module is configured to determine an exposure value based on the filtered section signal. S82. The system of any of the preceding embodiments having the features of S79, wherein the control module is configured to spatially filter the captured signal to reduce spatial luminance gradients, in particular to smooth luminance values. S83. The system of any preceding embodiment having the features of S30, wherein the control module is configured to receive a target acquisition interval, the target acquisition interval not including any active intervals, and / or the control module is further configured to determine a maximum allowable beam intensity value and / or a maximum exposure value with reference to the target acquisition interval. S84. A system as described in any of the preceding embodiments having the feature of S83, wherein the control module is configured to incrementally increase an inactive interval per capture interval of the capture sequence and / or incrementally decrease an active interval per capture interval of the capture sequence, and / or determine an exposure value for at least one capture interval of the capture sequence or for each capture interval of the capture sequence, and / or set a control interval that includes only an inactive interval and does not include an active interval based on the exposure value of at least one capture interval of the capture sequence. S85. The system of any preceding embodiment having the features of S30, wherein the control module is configured to match a maximum safe exposure value to a maximum safe capture interval. S86. The system of any preceding embodiment having the features of S30, wherein the control module is configured to determine an optimal safe capture interval. S87. The system of any preceding embodiment having the feature of S30, wherein the control module is configured to determine a minimum exposure value and set a control interval based on the minimum exposure value such that the beam signal is captured and registered within a captured signal above the noise floor of the sensor and / or such that the potential increase in exposure value to a maximum safe exposure value is maximized. S88. A system as described in any of the preceding embodiments, wherein the sensor is configured to capture the beam signal at an acquisition rate above a minimum acquisition rate threshold, particularly to provide a flicker-free, continuously updated acquisition signal. S89. A system according to any of the preceding embodiments, wherein the capture rate is decoupled from the beam exposure interval defined by the total activation time per capture interval and / or the capture rate is independent of the sequence of active and inactive intervals. S90. The system of any of the preceding embodiments, wherein the control module is configured to adjust the control interval such that the BCD is activated when the capture interval ends and / or when the capture interval starts.

[0198] Discussed below are method embodiments. These embodiments are abbreviated by the letter "M" followed by a number. These embodiments are meant whenever reference is made herein to "method embodiments." M1. A method for sensor protection in electronic imaging applications, comprising: A method comprising providing a modified beam signal based on an incident beam signal by varying an intensity of the modified beam signal over a predetermined time interval. M2. Acquiring a beam signal, in particular a modified beam signal and / or an incident beam signal, with a given spatial resolution and / or a variable time resolution; 4. The method of claim 1, further comprising: providing a capture signal based on the captured beam signal. M3. The method of any of the preceding embodiments, comprising stopping the incident beam signal from propagating through the BCD, in particular the blanker, in an initial propagation direction of the incident beam signal when the BCD is activated. M4. The method of any of the preceding embodiments, comprising providing a switchable physical barrier configured to at least partially intersect an initial propagation direction of the incident beam signal. M5. The method of any of the preceding embodiments, comprising providing an electrostatic field such that an initial propagation direction of the incident beam signal and a modified propagation direction of the modified beam signal are at an angle with respect to each other by activating an electrostatic shutter. M6. The method according to any of the preceding embodiments, comprising the step of providing an electromagnetic field, in particular a periodic electromagnetic field, such that the initial propagation direction of the incident beam signal and the modified propagation direction of the modified beam signal are at an angle with respect to each other by activating an electromagnetic shutter. M7. The method of any of the preceding embodiments, comprising adjusting, in particular reducing, the intensity of the incident beam to provide a modified beam having an intensity substantially equal to or lower than the incident beam. M8. The method of any of the preceding embodiments, comprising blocking at least a portion of a cross-section of the incident beam. M9. The method of any of the preceding embodiments, comprising, when activated, transforming a cross-section of an incident beam. M10. The method of any of the preceding embodiments, comprising at least partially reflecting and / or deflecting an incident beam signal. M11. The method according to any of the preceding embodiments, comprising focusing and / or defocusing an incident beam signal, in particular by increasing and / or decreasing a cross-section of the incident beam in the image plane. M12. A method according to any of the preceding embodiments, comprising transmitting a first portion of the incident beam signal towards an imaging plane and transmitting a second portion of the incident beam signal towards a second imaging plane, wherein a surface normal of the imaging plane and a further surface normal of the second imaging plane are angled relative to each other. M13. The method of any of the preceding embodiments, comprising shaping a cross-section of an incident beam signal, particularly by partially blocking the incident beam signal. M14. The method of any of the preceding embodiments, comprising modifying a beam intensity profile over a time interval. M15. The method of any of the preceding embodiments, comprising moving the BCD relative to an initial propagation direction of the incident beam signal. M16. The method of any of the preceding embodiments, comprising translating and / or rotating the BCD to an active position that enables the BCD to provide a modified beam signal, and / or translating and / or rotating the BCD to an inactive position that disables the BCD to provide a modified beam signal. M17. The method of any of the preceding embodiments, comprising: receiving a control signal; and activating a BCD based on the control signal. M18. The method of any of the preceding embodiments, comprising activating the BCD for the duration of the activation time interval. M19. The method of any of the preceding embodiments, comprising specifying an activation time interval by a control signal. M20. The method of any of the preceding embodiments, comprising adjusting an interaction between the BCD and the incident beam signal based on a control parameter. M21. The method of any of the preceding embodiments, comprising modifying beam characteristics of the incident beam signal based on a control parameter. M22. The method of any of the preceding embodiments, comprising preventing the incident beam signal from propagating further through the BCD in the initial propagation direction based on the blocking signal. M23. The method of any of the preceding embodiments, comprising activating and / or deactivating a BCD based on a timing parameter. M24. The method of any of the preceding embodiments, comprising: receiving an emergency shutoff signal; and, based on the emergency shutoff signal, preventing the incident beam signal from passing through the BCD and further propagating in the initial propagation direction. M25. The method of any of the preceding embodiments, comprising providing a control signal to a BCD. M26. The method according to any of the preceding embodiments, comprising the steps of generating an exposure value based on the capture signal, and modifying the control signal, in particular the control interval, based on the exposure value. M27. The method of any of the preceding embodiments, comprising increasing the active interval and / or decreasing the inactive interval when the exposure value exceeds an upper threshold, and / or decreasing the active interval and / or increasing the inactive interval when the exposure value falls below a lower threshold. M28. The method of any of the preceding embodiments, comprising: adjusting the control intervals such that the control intervals include active intervals during which the BCD is active and inactive intervals during which the BCD is inactive; and modifying a ratio of active intervals to inactive intervals based on an exposure value. M29. The method of any of the preceding embodiments, comprising increasing each active interval when the exposure value exceeds an upper threshold, and / or decreasing each active interval when the exposure value falls below a lower threshold. M30. The method of any of the preceding embodiments, comprising decreasing each inactive interval when the exposure value exceeds an upper threshold, and / or increasing each inactive interval when the exposure value falls below a lower threshold. M31. The method of any of the preceding embodiments, comprising adjusting the interval duration of the active interval and the further interval duration of the inactive interval such that the interval frequency remains constant. M32. The method of any of the preceding embodiments, comprising the step of providing the control signal to the BCD continuously or when the control signal changes. M33. The method of any of the preceding embodiments, comprising controlling the interval frequency based on the exposure value to match the exposure value to a predetermined base exposure value. M34. The method of any of the preceding embodiments, comprising adjusting a control interval based on a capture frequency of the sensor. M35. The method of any of the preceding embodiments, comprising modifying the interval duration of the active interval and / or the further interval duration of the inactive interval at a frequency below the capture frequency. M36. The method of any of the preceding embodiments, comprising entering a limit mode when the exposure value exceeds a predetermined limit threshold. M37. The method of any of the preceding embodiments, comprising applying pulse width modulation (PWM) to the control interval to control the averaged beam intensity of the modified beam signal during the control interval. M38. The method according to any of the preceding embodiments, comprising a step of adjusting the PWM of the control interval, in particular controlling the averaged beam intensity, to achieve a predetermined exposure value, in particular a maximum safe exposure value. M39. The method of any of the preceding embodiments, comprising applying a duty cycle limiting control to a control interval to limit the beam intensity during an interval of capture of the beam signal by the sensor. M40. The method according to any of the preceding embodiments, comprising a step of adjusting the duty cycle of the control interval, in particular a step of controlling the beam intensity to achieve a predetermined exposure value, in particular a maximum safe exposure value. M41. The method of any of the preceding embodiments, comprising entering an evaluation mode when receiving a trigger signal. M42. The method of any of the preceding embodiments, comprising setting a control interval comprising a predetermined maximum active interval and / or comprising a minimum inactive interval. M43. The method of any of the preceding embodiments, comprising incrementally increasing the inactive interval per acquisition interval and / or incrementally decreasing the active interval per acquisition interval, particularly during a subsequent series of acquisition intervals. The method of any of the preceding embodiments, comprising applying M44. PWM to the control intervals to limit the exposure value and incrementally increase the number of active intervals and / or the duration of active intervals per capture interval. M45. The method of any of the preceding embodiments, comprising the step of determining an increase in exposure value per capture interval by reference to a previous capture interval. M46. The method of any of the preceding embodiments, comprising the step of terminating the evaluation mode when the difference between the current exposure value and the maximum safe exposure value is less than the predicted increase in exposure value in the subsequent capture interval. M47. The method of any of the preceding embodiments, comprising the step of terminating the evaluation mode when the determined exposure value falls below a maximum safe exposure value and / or when the control interval comprises a predetermined ratio of active intervals to inactive intervals, preferably when the control interval comprises only inactive intervals. M48. The method of any of the preceding embodiments, comprising maintaining a control signal with a control interval comprising a pattern of active and inactive intervals corresponding to a last exposure value determined in the evaluation mode. M49. The method according to any of the preceding embodiments, comprising a step of controlling the exposure value of a subsequent capture interval, preferably a number of subsequent capture intervals, to the exposure value determined in the evaluation mode, in particular the exposure value last determined in the evaluation mode. M50. The method of any preceding embodiment, comprising adjusting the active spacing pattern while maintaining the last exposure value determined in the evaluation mode. 5. The method of any of the preceding embodiments, comprising converting a PWM active interval pattern into consecutive active intervals per capture interval. M52. The method of any of the preceding embodiments, comprising setting an attenuation parameter to control the intensity of the modified beam signal. M53. The method of any of the preceding embodiments, comprising increasing the beam intensity per capture interval and determining an exposure value for each increase. M54. The method of any of the preceding embodiments, comprising decreasing the active interval such that the beam intensity and / or exposure value is increased by a fixed amount per capture interval. M55. The method according to any of the preceding embodiments, comprising a step of decreasing the active interval such that the beam intensity and / or exposure value is increased per capture interval according to a predetermined relationship, in particular by a fixed factor. M56. The method of any of the preceding embodiments, comprising: predicting a first exposure value for a subsequent capture interval based on an exposure value of a previous capture interval; and setting a control interval for the subsequent capture interval based on the first exposure value. M57. A method according to any of the preceding embodiments, comprising predicting a second exposure value for a further capture interval following a subsequent capture interval based on an exposure value of a previous capture interval, setting a control interval for the subsequent capture interval, and / or setting a further control interval for the further capture interval, and / or determining whether the second exposure value is less than or equal to a maximum safe exposure value. M58. The method according to any of the preceding embodiments, preferably comprising the step of setting a control interval for a subsequent capture interval based on the further capture interval, in particular to replace the subsequent capture interval with the further capture interval when the second exposure value is less than or equal to a maximum safe exposure value or falls below the maximum safe exposure value by a predetermined margin value. M59. The method of any of the preceding embodiments, comprising predicting an exposure value for each capture interval in a capture sequence comprising a series of subsequent capture intervals. M60. The method of any of the preceding embodiments, comprising a step of decreasing a total activation time, corresponding to a total duration of active intervals per acquisition interval, for successive acquisition intervals in an acquisition sequence. M61. The method of any of the preceding embodiments, comprising setting a first total activation time for a first capture interval of a capture sequence to a second total activation time of a second capture interval of the capture sequence. M62. The method of any of the preceding embodiments, comprising the step of reducing a total activation time of a capture interval by an amount equal to the combined reduction in the total activation time of at least two subsequent capture intervals of the capture sequence, particularly when the reduction results in a predicted exposure value below a maximum safe exposure value. M63. The method according to any of the preceding embodiments, comprising adjusting a predicted exposure value of a capture interval of a capture sequence based on a determined exposure value of the capture interval, in particular a previous capture interval of the capture sequence. M64. The method of any of the preceding embodiments, comprising adjusting a rate of decrease in total activation time per capture interval within a capture sequence. M65. A method according to any of the preceding embodiments, comprising: dividing a capture signal into a set of section signals, each section signal comprising a coherent subset of the capture signal; and determining a section exposure value for each section signal. M66. The method of any of the preceding embodiments, comprising overlapping coherent subsets of captured signals defining section signals along at least one dimension of the beam signal, preferably spatially overlapping the coherent subsets by at least 25%, more preferably spatially overlapping the coherent subsets by at least 50%. M67. The method of any of the preceding embodiments, comprising activating a BCD and / or entering an evaluation mode when a section exposure value for a signal section exceeds a maximum section exposure value. M68. The method of any of the preceding embodiments, comprising filtering the captured signal to generate a filtered captured signal. M69. The method according to any of the preceding embodiments, comprising the step of applying a filter to each section signal, in particular applying filtering to all section signals in parallel to generate filtered section signals. M70. The method of any of the preceding embodiments, comprising determining an exposure value based on the filtered section signal. M71. The method of any of the preceding embodiments, comprising a step of spatially filtering the captured signal to reduce spatial intensity gradients, in particular to smooth the intensity values. M72. A method according to any of the preceding embodiments, comprising receiving a target acquisition interval, the target acquisition interval not including any active intervals, and / or determining a maximum allowable beam intensity value and / or a maximum exposure value with reference to the target acquisition interval. M73. A method according to any of the preceding embodiments, comprising incrementally increasing an inactive interval per capture interval of the capture sequence, and / or incrementally decreasing an active interval per capture interval of the capture sequence, and / or determining an exposure value for at least one capture interval of the capture sequence or for each capture interval of the capture sequence, and / or setting a control interval that does not include any active intervals and includes only inactive intervals based on the exposure value of at least one capture interval of the capture sequence. M74. The method of any of the preceding embodiments, comprising matching a maximum safe exposure value to a maximum safe capture interval. M75. The method of any of the preceding embodiments, comprising determining an optimal safety capture interval. M76. The method of any of the preceding embodiments, comprising determining a minimum exposure value and setting a control interval based on the minimum exposure value such that a beam signal is captured and registered within the captured signal above the noise floor of the sensor and / or such that the potential increase in exposure value to a maximum safe exposure value is maximized. M77. The method of any of the preceding embodiments, particularly comprising acquiring a beam signal at an acquisition rate above a minimum acquisition rate threshold to provide a flicker-free, continuously updated acquisition signal. M78. The method of any of the preceding embodiments, comprising adjusting a control interval such that the BCD is activated when a capture interval ends and / or when a capture interval starts. [Brief description of the drawings]

[0199] The invention will now be described with reference to the accompanying drawings, which illustrate embodiments of the invention and are given by way of example only and are not intended to be limiting. [Figure 1] FIG. 2 is a diagram illustrating an embodiment of applying an evaluation mode according to the present invention. [Diagram 2]FIG. 2 is a diagram that illustrates a schematic depiction of a sequence of capture intervals according to an embodiment of the present invention; [Diagram 3] FIG. 13 is a diagram that illustrates a schematic depiction of a further sequence of capture intervals according to an embodiment of the present invention; [Figure 4] FIG. 2 is a diagram that depicts a schematic of a control scheme according to one embodiment of the present invention. [Diagram 5] FIG. 2 is a diagram that illustrates a schematic depiction of multiple overlapping section signals according to an embodiment of the present invention; [Figure 6] FIG. 2 is a diagram that illustrates a schematic depiction of a capture sequence and an imaging device according to an embodiment of the present invention. [Figure 7] FIG. 2 is a diagram that illustrates a schematic depiction of the relationship of BCD state, beam intensity, and sensor readout to multiple PWM parameters, in accordance with an embodiment of the present invention. [Figure 8] FIG. 2 is a diagram that illustrates a schematic depiction of the relationship of BCD state, beam intensity, and sensor readout to a number of selected PWM parameters, in accordance with an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0200] It should be noted that not all drawings have all reference numbers, and instead, in some drawings, some of the reference numbers have been omitted for brevity and ease of illustration.Embodiments of the present invention will now be described with reference to the accompanying drawings, in which:

[0201] FIG. 1 shows a flow chart for the execution of the evaluation mode. When the evaluation mode is triggered, the exposure of the sensor is set to a predetermined initial value. In particular, the control interval may preferably include a predetermined ratio of active interval to inactive interval with respect to the capture interval. For example, the inactive interval may be set to T=10 μs, so that for the first capture interval in the evaluation mode, the sensor is exposed to the beam signal for a duration of 10 μs. The setting of the initial control parameters may be performed in step 101. Following the setting of the control parameters, a reset frame may be acquired in step 102. Acquiring the reset frame may be optional. The reset frame may form the basis for further evaluation of the subsequently captured beam signal exposure. When the initial parameters are set or acquired, the BCD may be deactivated, i.e. the shutter may be released (step 103). In parallel with releasing the shutter, the first capture data may be acquired (step 1041). This data may preferably be an initial data frame that is not used to evaluate, i.e. to quantify, the exposure. Acquisition of the initial data frame 1041 may be optional. The capture interval may include a 10 μs window during which the beam signal is exposed to the sensor.

[0202] The system may in particular implement a version of Multi Frame Correlated Double Sampling (MFCDS) according to US Pat. No. 8,817,148 (B2), which is incorporated herein in its entirety. A reset frame according to the invention may be used to achieve a predefined state for each pixel of the sensor. CDS is particularly useful when the sensor is a CMOS sensor, as it reduces the noise caused by Fixed Pattern Noise (FPN) and Reset Noise. It can be used to reduce noise (RN).

[0203] Capturing the beam signal 1042 for the evaluation of the exposure can provide a basis for evaluating whether the beam intensity peak is captured by the sensor. In particular, the control module can identify in step 1043 whether the beam trajectory coincides with the sensor position, i.e. whether the maximum of the beam signal actually hits the sensor. The control module can implement different frames to determine the state of the exposure of the sensor, i.e. whether the beam signal is captured by the sensor, preferably to distinguish whether the beam signal is partially or completely captured. This can include compensation of the data captured in the dark frames and / or the reset frames. For example, the reset frame E0 can be compensated by a corresponding dark frame D0:E0-D0, and the data frame E2 can also be compensated by a further corresponding dark frame D2:E2-D2. In this way, whether the beam is captured by the sensor can be determined based on the difference (E2-D2)-(E0-D0). The control module can also check this difference for overexposure.

[0204] When the beam signal is captured, the exposure may be evaluated 105. The control module may determine safe exposure conditions. When the current exposure value is within safe limits and / or when a subsequent setting is predicted to be within safe limits, the inactivity interval, i.e., the time interval between exposures of the beam signal to the sensor, may be increased 107. The exposure interval may be increased by a predetermined factor (e.g., 2).

[0205] Based on the evaluated exposure, the control module can set an exposure increase higher than a predetermined factor or a predetermined increase amount. Thus, when the exposure having a higher value is determined to be below the maximum exposure value, an exposure step can be skipped. Preferably, the increase can be measured in duty cycle percentages. For example, the control module can be configured to determine that a 50% duty cycle exposure produces an exposure value within a safe limit based on an exposure value determined from a 2% duty cycle exposure. Thus, the control module can skip the incremental increases between 2% and 50% and directly perform a 2% duty cycle exposure followed by a 50% duty cycle exposure. The skip increase can vary based on accuracy and confidence values ​​associated with the initial exposure, i.e., the exposure value determined based on the 2% duty cycle exposure.

[0206] The evaluation mode may be triggered by an interface of the system and / or by a pre-dose protection mechanism that monitors the current exposure value with reference to parameters acceptable to the system, e.g., exposure values ​​within set minimum and / or maximum thresholds. Additionally, changes to the system, e.g., adjustments to the optics, changing the specimen, changing BCD settings, may trigger the evaluation mode to again verify that the system is operating within predefined threshold parameters.

[0207] When it is determined in step 105 that the current exposure does not fall within the predefined threshold parameters, e.g., the exposure value exceeds the maximum exposure value, the system can issue a report including the current parameters, specifically the current exposure interval (e.g., 10 μs). Additionally or alternatively, the control module can revert to a previous set of parameters that were deemed safe. However, these settings can also be reevaluated to determine whether these previous parameters still produced captured data within the predefined threshold parameters. Based on the report, and particularly by the control module, avoidance action can be implemented when the margin between the current exposure value and the threshold is undercut, thus increasing the margin.

[0208] A significant optical mode change may be indicated manually and / or automatically by subsystems of the system. A significant optical mode change may trigger a switch to an evaluation mode. During the evaluation mode, the system may determine whether the illumination of the sensor is acceptable or not. The evaluation mode may be a proactive dose protection. Following the evaluation mode, a normal exposure mode may be performed during which reactive dose protection is active, i.e., the capture of the beam signal may be interrupted when overexposure is detected.

[0209] FIG. 2 diagrammatically depicts a sequence of capture intervals according to an embodiment of the present invention. Frame 201 may be a reset frame. Each capture frame labeled with an even number (202, 204, 206, ...) may be divided into a set of two frames, the first of which may correspond to an initial data frame and the second of which may be a detection frame used to determine the exposure of the beam signal. These detection frames labeled with odd numbers (203, 205, 207, ...) may correspond to an exposure time interval, i.e., an inactive interval per capture frame during which the beam signal is exposed to the sensor. Correspondingly, T may represent an exposure time increment, particularly with reference to a previously captured frame. For example, an initial capture interval may include a beam exposure of tc=10 μs, and a subsequent capture interval may include a beam exposure of tc=20 μs such that T=10 μs. A minimum number of capture intervals to be evaluated within the evaluation mode may be set. For example, a minimum number of 20 capture intervals, i.e., frames, may be set. Additionally or alternatively, a minimum total exposure time may be set, for example a minimum total exposure time of 80 ms.

[0210] FIG. 3 illustrates a schematic depiction of a further sequence of capture intervals according to an embodiment of the present invention. In particular, the exposure window, i.e., the inactive interval during the capture interval, may be increased up to or beyond the capture interval. For example, the full length capture interval may be 4000 μs. The inactive interval length may be increased by a constant multiple of 2, resulting in an interval length of 5120 μs. Thus, the final capture interval during the evaluation mode may be characterized by a fully deactivated BCD, i.e., exposure of the beam signal to the sensor for the entire duration of the capture interval. The evaluation mode may test partial doses to determine and / or predict exposure at full dose. For example, the total dose of the beam signal per pixel during the capture interval where the BCD does not block the beam signal may reach 10 nA per pixel. A minimum exposure time interval, i.e., a minimum inactive interval of 10 μs and a minimum of 1.5×10 9In conjunction with a maximum lifetime dose per pixel of A, the sensor can capture approximately 2430 frames with a 10 μs exposure window and an intensity of 10 nA per pixel before reaching its lifetime projection. For example, the sensor can capture 1 / 800th of the radiation with a 10 μs exposure window as opposed to a full length exposure of 8 ms. th Furthermore, 10 nA can represent an exceptionally high intensity for a pixel, including for diffractive applications. Preferably, the maximum intensity per pixel can be approximately 1 nA.

[0211] FIG. 4 shows a schematic of a control scheme according to an embodiment of the present invention. The diagram is based on a time axis running from left to right, i.e. starting from a trigger signal (e.g. OpticalModeChange). The evaluation modes can be triggered by a specific trigger event or signal. For example, an optical mode change can trigger a dose protection. An optical mode change can include normalization, a change to diffraction, a beam stop retraction and / or an image shift due to a beam stop being inserted, i.e. activated. BCD, i.e. enabling a protection shutter (ForceBlank(On)), can represent a control interval that includes only an active interval. Dose protection can be initiated based on a dose change. Furthermore, the dose can be unpredictable, e.g. due to changes in the optics. For this reason, a BCD can be triggered to prevent the sensor from being exposed to a beam signal with an unknown intensity.

[0212] The dose protector may be part of the control module. In particular, the dose protector may issue a ForceBlank signal that may replace any evaluation mode or other control signal for activation / deactivation of the BCD. As long as the ForceBlank signal is set to "on", the BCD may remain active and block the beam signal. The ForceBlank signal may also be set to "on" in anticipation of a beam intensity change and / or in anticipation of a trigger event. The control over the BCD may be transferred from the software level to the hardware level. Preferably, this may be implemented once the BCD becomes active based on the ForceBlank signal. In particular, there may be a time interval between the activation of the BCD and the actual change of the beam signal based on the ForceBlank signal. In the embodiment shown, this time interval is indicated by "Change Optics". Preferably, during this time interval the evaluation mode may be initialized.

[0213] In preparation for evaluation mode (preparation for sniffing), the Hardware Blank (HwBlank) signal may be set to "on" representing a further signal instance related to the activation / deactivation of the BCD. However, the HwBlank signal may be issued by the control hardware layer as opposed to the control software layer. Evaluation mode initialization (sniffing) may be performed asynchronously. Once the HwBlank signal is established, protection via the dose protector (ForceBlank, software level) may be disabled, i.e., the ForceBlank signal may be set to "off". Sniffing and evaluation mode are used synonymously since sniffing may be defined as capturing the beam signal for only a portion of the actual exposure interval to be achieved and incrementally increasing that portion until the requested exposure interval can be met or a system threshold is exceeded, preventing further increase.

[0214] During the interval between "DoseRate ToChange" and "DoseRate Changed", the beam intensity may be unpredictable. The "DoseRate ToChange" and "DoseRate Changed" signals may be set automatically after a particular beam intensity change operation is completed and / or these signals may be set by manual interface operations.

[0215] The "DoseRate Changed" signal can trigger a delay before triggering the evaluation mode to allow the optics to stabilize. The request to start the evaluation mode can be asynchronous. With the request to start the evaluation mode, control can be transferred from the dose protector to the camera software and the actual capture acquisition, including BCD control, can be transferred to the hardware level.

[0216] When a request to start the evaluation mode (sniffing) is issued to the camera software, the dose measurement can in turn be started by the camera software. The actual acquisition of the capture intervals, including the control of the BCD during the acquisition, can be controlled by the camera hardware. Measuring the dose can include evaluating multiple capture intervals and / or deactivating / activating the BCD for multiple intervals. When the camera hardware issues a HwBlank signal with a value "off", the BCD can be deactivated, i.e., can start an inactive interval. When the camera hardware issues a HwBlank signal with a value "on", the BCD can be activated, i.e., can start an active interval and can end an inactive interval. Each capture signal can include multiple active intervals. The process of measuring the dose can be stopped when an unsafe dose has been captured by at least one capture interval, i.e., when the exposure threshold has been exceeded by at least one pixel or a significant number of pixels. When the current exposure value is deemed unsafe to expose the sensor to further exposure, control can be given from the camera software to the dose protector, which in turn can issue a forced activation of the BCD by providing a ForceBlank signal with value "on". Thus, the sensor can be protected from overexposure, respectively high beam intensity.

[0217] When the evaluation mode can be completed without the full exposure trigger threshold parameter, the evaluation mode (dosimetry) can be completed and normal acquisition of the beam signal can proceed.

[0218] The control module may be configured to provide a dose margin value indicative of the difference between the current exposure value and / or beam intensity and a respective threshold value.

[0219] Additionally, the system can be configured to react to failure of any component by having the BCD activate and / or trigger the secondary BCD if the primary BCD also fails. The control module can identify a failed component or a fault condition of the system in general based on the beam intensity and / or beam intensity pattern (temporal and / or spatial) at the sensor. When the beam signal deviates from an expected range of a parameter, the control module can trigger the BCD to protect the sensor. For example, a failure can be detected if a significant dose is detected even though the beam blanking signal is active (on). The control module can detect a failure of any component (e.g., optics, BCD position, etc.). Detecting a failure can also trigger an evaluation mode.

[0220] FIG. 5 shows a schematic sequence 500 of overlapping section signals 50#, where # represents a positive integer. In particular, the sections overlap by 50% such that each sensor section is represented as part of two separate section signals. An exemplary beam signal is shown as two circles. Thus, the first circle is fully captured by section signal 501 and partially captured by section signal 502, and the first circle is not part of section signal 503. The probability of splitting the beam signal at a section signal edge due to the overlap can be reduced, i.e., the chance of capturing the beam signal without at least one section crossing a section edge can be increased. Capturing the complete beam signal, or at least a cohesive domain of the beam signal within a single section signal, can increase the accuracy of the determined exposure value of each section signal. When the beam signal is split across multiple section signals, the exposure value generated for each section signal may not trigger the exposure threshold because each section may not contain a significant portion of the beam signal to trigger a brightness alert for its respective section signal. The overlap can be implemented in two or more directions, i.e., transverse, lateral, and / or diagonal. The overlap may be varied according to the type of beam signal expected and the likelihood that the relevant coherent portions of the beam signal may be divided across the section signals.

[0221] The secondary circle is partially captured by section signals 504, 505 and 506l. None of the section signals capture the secondary circle completely. However, due to sectioning, section signal 505 is an approximation of a section that would have completely surrounded the secondary circle. The control module can be configured to determine an exposure value for section 505 and weight the exposure value based on exposure values ​​determined for sections 504 and / or 506, i.e., adjacent sections capturing the same aggregate beam signal portion, to estimate a true exposure value corresponding to a section signal that completely captures the secondary circle. As a result, the overlapping sections allow for a more accurate determination of exposure, thus increasing the probability of avoiding sensor damage due to undetected overexposure.

[0222] 6 depicts a schematic representation of continuous exposure in imaging 601, where the beam signal is continuously exposed to a sensor. The sensor captures the beam signal at segmented capture intervals. The exposure time is equal to the capture interval length.

[0223] FIG. 6 further depicts a schematic representation of a pulsed exposure in diffraction 602, where the exposure time is controlled by the BCD. Each capture interval includes an exposure interval based on the BCD being inactive at the beginning of each capture interval (frame). Typically, a diffraction image can include significantly higher beam intensity compared to a reflection continuous imaging. Due to spot-like intensity peaks, it is essential to accurately detect the brightness of these spots to protect and increase the life of the sensor.

[0224] The system 600 can include a BCD (e.g., beam blanker, cavity, etc.) for exposing the sample (e.g., for an exposure duration of 1 ms or less) and a sensor providing a frame rate of 20 fps or more. For example, the sensor can be read out at a readout frequency of 25 Hz, the sample exposure interval can be based on an exposure frequency of 1 khz, and the dose can be reduced by a factor of 40. With an exposure frequency of 10 kHz, a reduction of 400 times can be achieved.

[0225] For example, in MS imaging, currents between 10 and 1000 pA can be used. On average, 100.000 pixels are captured in a 16 × 10 6 When illuminated on a pixelated sensor, this can average approximately 1-100 pe / pixel per 25 fps. A readout frequency of 25 fps or higher allows the operator to smoothly observe changes in the diffraction pattern. A lower readout frequency can cause jitter effects, which can tire the operator.

[0226] The diffraction pattern 602 of Si110 can contain intensities in the diffraction spot on the order of 100-600 counts, which can be equal to 5-30 primary electrons. In this dose range, misorientation of the crystals is observable. Exposure times can be 3.3 ms and 300 fps, respectively, at a current of 1 pA. Smooth live images can be achieved by reducing the dose for orientation by a factor of 10.

[0227] FIG. 7 depicts four stacked diagrams sharing a common x-axis showing time. The top graph represents the progression of the camera line readout. Thus, T1 indicates the time interval in which the sensor completes the readout of all lines, i.e. a complete frame. The camera readout rate can be linear. The second graph shows the beam intensity to which the sensor is exposed during the capture interval T1 with a 100% duty cycle. The duty cycle can be related to the PWM actuation of the BCD. Here, a 100% duty cycle can be related to the BCD being inactive for the complete capture interval. Thus, the beam signal is exposed at full intensity for the entire duration of the capture interval. It is further shown that a 100% duty cycle can correspond to the BCD being inactive for a series of subsequent frames, since there is no active interval for the BCD in the control signal.

[0228] Alternatively, the control module can implement a 50% duty cycle PWM such that the BCD is inactive for half the capture interval and active for the other half of the capture interval. A specific example is one aggregate inactive interval t オン Specifically, at the end of each capture interval, there is one aggregate active interval t オフ and indicates.

[0229] Additionally, the control module may implement a 5% duty cycle PWM such that the BCD is inactive for 5% of the capture interval, specifically at the beginning of the capture interval.

[0230] FIG. 8 illustrates a schematic representation of a further embodiment of an interval sequence according to the present invention. T1 corresponds to a capture interval during which a complete readout of the sensor can be performed. A complete readout can be defined as transmitting a single exposure from the sensor. The sensor can capture multiple exposures, which can then be read out sequentially from the sensor. As an alternative to the 50% PWM duty cycle embodiment shown in FIG. 7, a 50% PWM duty cycle can be spread over the capture interval according to a predefined PWM frequency. The PWM frequency can be determined by a PWM period T2. The interval T2 can include a PWM pattern that is repeated within the capture interval. Preferably, the capture interval is a multiple of the interval T2. The interval T2 can include an active interval and an inactive interval. In particular, T2 can include an active interval and an inactive interval having the same duration corresponding to a 50% PWM duty cycle.

[0231] Furthermore, FIG. 8 shows a 10% PWM duty cycle spread over one capture interval, where T オンconstitutes 10% of one PWM period T2. Thus, an embodiment with a 10% PWM duty cycle has the same PWM frequency as an embodiment with a 50% PWM duty cycle. Preferably, the capture interval and / or PWM interval begins with an inactive interval, i.e., the beam signal is exposed to the sensor at the beginning of each capture interval. T over one capture interval オン The sum of the intervals can amount to a respective percentage of the capture interval, ie, for a 10% PWM duty cycle, 10% of the capture interval can be an inactive interval.

[0232] 8 also illustrates an embodiment with a 2% PWM duty cycle. The PWM frequency is based on the PWM interval T3, where the capture frequency is not an integer multiple of the PWM frequency such that the PWM modulation is asynchronous with the capture interval. Furthermore, the duty cycle interval T オン is the T of the 10% PWM duty cycle embodiment. オン When the minimum inactive interval is reached, a further reduction in exposure may be made to the duty cycle interval T オン This can be achieved by keeping constant the PWM frequency and increasing the PWM interval, respectively.

Claims

1. 1. A system for sensor protection in electronic imaging applications, comprising: a beam control device (BCD) configured to provide a beam signal based on an incident beam signal, the beam signal including a modified beam intensity, the BCD further configured to receive a control signal and to activate based on the control signal; a sensor configured to acquire the beam signal and provide an acquisition signal based on the beam signal; a control module configured to provide the control signal to the BCD, generate an exposure value based on the captured signal, and modify the control signal based on the exposure value; The system, wherein the BCD is configured to activate for the duration of an active interval, and the control module is configured to decrease the active interval while the exposure value does not exceed an upper threshold.

2. 2. The system of claim 1, wherein the control module is configured to: enter an evaluation mode when the control module receives a trigger signal; set a control interval that includes a predetermined maximum active interval; and incrementally decrease the active interval per capture interval for a subsequent series of capture intervals.

3. 2. The system of claim 1, wherein the control signal includes a control interval having the active interval, and the control module is configured to apply pulse width modulation to the control interval to control an averaged beam intensity of the modified beam signal during the control interval.

4. The system of claim 1 , wherein the control module is configured to determine the increase in exposure value per capture interval by reference to a previous capture interval.

5. The control module detects whether a condition: the captured exposure value is below a maximum safe exposure value and the control interval comprises a predetermined ratio of active interval to inactive interval; the difference between the current exposure value and said maximum safe exposure value is less than the predicted increase in said exposure value in the subsequent capture interval; The system of claim 1 , further configured to terminate the evaluation mode when at least one of the following conditions is met: the control interval includes only an inactivity interval.

6. The system of claim 5 , wherein the control module is configured to control the exposure value of a subsequent capture interval to the exposure value determined in the evaluation mode.

7. The system of claim 1 , wherein the control module is configured to decrease the active interval such that the exposure value is increased according to a predetermined relationship per capture interval.

8. 2. The system of claim 1, wherein the control module is configured to: predict an exposure value for a selected capture interval of a subsequent capture interval sequence based on the exposure value of a previous capture interval; determine whether the exposure value is less than or equal to a maximum safe exposure value; and set the control interval of the subsequent capture interval based on a control interval of the selected capture interval, wherein the selected capture interval is greater than or equal to a second position in the subsequent capture interval sequence.

9. 2. The system of claim 1, wherein the control module is configured to predict an exposure value for each capture interval in a capture sequence including a series of subsequent capture intervals, and a total activation time corresponding to a total duration of active intervals per capture interval decreases for successive capture intervals in the capture sequence.

10. 2. The system of claim 1, wherein the control module is configured to: divide the capture signal into a set of section signals, each section signal comprising a coherent subset of the capture signal; determine a section exposure value for each section signal; overlap the coherent subsets of the capture signals that define the section signals along at least one dimension of the beam signal; and activate the BCD when a section exposure value for a signal section exceeds a maximum section exposure value.

11. The system of claim 1 , wherein the control module is configured to spatially filter the captured signal to reduce spatial intensity gradients.

12. 2. The system of claim 1, wherein the control module is configured to receive a target acquisition interval, the target acquisition interval not including any active intervals, and / or the control module is further configured to: determine a maximum allowable beam intensity value and / or a maximum exposure value with reference to the target acquisition interval; incrementally decrease the active interval per acquisition interval of a capture sequence; determine an exposure value for at least one acquisition interval of the capture sequence; and set a control interval that does not include an active interval based on the at least one exposure value of a capture interval of the capture sequence.

13. 1. A method for sensor protection in electronic imaging applications, comprising: - providing a modified beam signal based on an incident beam signal by varying the intensity of said modified beam signal over a predetermined time interval; - acquiring said modified beam signal and providing an acquisition signal based on said acquired beam signal; - generating an exposure value based on said captured signal and modifying a control signal based on said exposure value; - increasing the active interval of said control signal when said exposure value exceeds an upper threshold.

14. - entering an evaluation mode when receiving a trigger signal; - setting a control interval corresponding to a given exposure value; - incrementally decreasing the active interval per acquisition interval in the evaluation mode; - exiting the evaluation mode when the captured exposure value falls below a maximum safe exposure value and the control interval comprises a predefined active interval.

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