Abstract: A method for driving an acousto-optic element with an acousto-optic crystal and a piezoelectric transducer for setting the acousto-optic crystal in mechanical vibration includes driving the piezoelectric transducer with a drive signal with at least one drive frequency. The at least one drive frequency in alternation takes on a plurality of different values around a center frequency during a passage of a mechanical vibrational wave through the acousto-optic crystal, such that a grating that is produced owing to density fluctuations in the acousto-optic crystal exhibits different grating spacings at the same time.

Abstract: An apparatus is configured to count N-photon events within a time-dependent sequence of events of interactions of a plurality of photons with a light sensitive detector. The apparatus includes a signal-processing device and the light sensitive detector. An N-photon event represents an occurrence of at least N timely overlapping single photon events. The light sensitive detector is adapted to generate a time-dependent digital signal comprising digital patterns representing the time-dependent sequence of events from the detection of the plurality of photons with the light sensitive detector. Each digital pattern in the digital signal comprises a digital pattern width having a continuous sequence of digital values representing at least one event of interaction of at least one photon with the light sensitive detector. The signal-processing device is adapted to identify N-photon events from the digital patterns in the digital signal in dependence from the respective digital pattern width.

Abstract: A method for evaluating a single-photon detector signal includes duplicating the single-photon detector signal into a first and a second signal. The first signal is processed and the second signal is either not processed or is processed in a manner different from the first signal. A differential signal is formed between the unprocessed or differently processed second signal and the processed first signal. The differential signal is evaluated to determine pulse events.

Abstract: A method for counting photons using a photomultiplier includes obtaining a measurement signal from a raw signal produced by the photomultiplier by correcting the raw signal for a noise signal and/or an offset, wherein an incident photon produces a pulse in the raw signal. The measurement signal is integrated over time to form an analog integrated measurement signal. A number of photons that are incident in the photomultiplier is ascertained by comparing a value of the analog integrated measurement signal to an integral proportionality value which corresponds to a specific number of photons incident in the photomultiplier.

Abstract: An electric circuit for driving an acousto-optic crystal includes a piezoelectric converter configured to drive the acousto-optic crystal to vibrate mechanically. A signaling cable is configured to conduct a first electrical alternating-current signal and a second electrical signal. The electric circuit further includes a first frequency-separating filter and a second frequency-separating filter, each of the frequency-separating filters having an input, a high-frequency output and a low-frequency output. The input of the first frequency-separating filter and the input of the second frequency-separating filter is connected to the signaling cable, and the high-frequency output of the second frequency-separating filter is connected to the piezoelectric converter.

Abstract: A fluorescence-lifetime imaging microscopy method with time-correlated single-photon counting includes using excitation light pulses separated in each case by a measurement interval to excite a sample to emit fluorescence photons. A detector signal that represents the captured fluorescence photons is generated. Detection times are determined based on the detector signal. Imaging is performed based on the detection times. The detection times of all captured fluorescence photons are compiled in a first data memory, common to a plurality of image pixels. The detection times of only those fluorescence photons which were captured in a predetermined number within the respective measurement intervals are compiled in a second data memory, common to the same plurality of image pixels. The detection times compiled in the data memories are combined within a calculation step. The results of the calculation step are stored in a third data memory.

Abstract: A fluorescence-lifetime imaging microscopy method with time-correlated single-photon counting includes using excitation light pulses separated in each case by a measurement interval to excite a sample to emit fluorescence photons. A detector signal that represents the captured fluorescence photons is generated. Detection times are determined based on the detector signal. Imaging is performed based on the detection times. The detection times of all captured fluorescence photons are compiled in a first data memory, common to a plurality of image pixels. The detection times of only those fluorescence photons which were captured in a predetermined number within the respective measurement intervals are compiled in a second data memory, common to the same plurality of image pixels. The detection times compiled in the data memories are combined within a calculation step. The results of the calculation step are stored in a third data memory.

Abstract: A method for counting photons using a photomultiplier includes obtaining a measurement signal from a raw signal produced by the photomultiplier by correcting the raw signal for a noise signal and/or an offset, wherein an incident photon produces a pulse in the raw signal. The measurement signal is integrated over time to form an analog integrated measurement signal. A number of photons that are incident in the photomultiplier is ascertained by comparing a value of the analog integrated measurement signal to an integral proportionality value which corresponds to a specific number of photons incident in the photomultiplier.

Abstract: A method forms a digital value from a clock signal and a digital data signal. The method includes sampling the clock signal in order to obtain a clock signal digital value sequence and sampling the digital data signal in order to obtain a data signal digital value sequence. Sampling points are ascertained from the clock signal digital value sequence, at which data signal digital values are extracted from the data signal digital value sequence. The digital value is formed from the data signal digital values.

Abstract: A method for driving an acousto-optic element with an acousto-optic crystal and a piezoelectric transducer for setting the acousto-optic crystal in mechanical vibration includes driving the piezoelectric transducer with a drive signal with at least one drive frequency. The at least one drive frequency in alternation takes on a plurality of different values around a center frequency during a passage of a mechanical vibrational wave through the acousto-optic crystal, such that a grating that is produced owing to density fluctuations in the acousto-optic crystal exhibits different grating spacings at the same time.

Abstract: A light/voltage converter circuit for converting intensity fluctuations of light into an alternating voltage measurement signal includes a photodiode configured to detect the light and a transformer comprising a primary coil and a secondary coil. The primary coil is connected in a series circuit to the photodiode, and the alternating voltage measurement signal is applied to the secondary coil. An electrical network is configured to block direct current and conduct alternating current. The electrical network is connected in parallel with the series circuit consisting of the primary coil of the transformer and the photodiode.

Abstract: A method for evaluating a single-photon detector signal includes duplicating the single-photon detector signal into a first and a second signal. The first signal is processed and the second signal is either not processed or is processed in a manner different from the first signal. A differential signal is formed between the unprocessed or differently processed second signal and the processed first signal. The differential signal is evaluated to determine pulse events.

Abstract: A method forms a digital value from a clock signal and a digital data signal. The method includes sampling the clock signal in order to obtain a clock signal digital value sequence and sampling the digital data signal in order to obtain a data signal digital value sequence. Sampling points are ascertained from the clock signal digital value sequence, at which data signal digital values are extracted from the data signal digital value sequence. The digital value is formed from the data signal digital values.

Abstract: A fluorescence lifetime imaging microscopy method with time-correlated single photon counting includes periodically exciting a sample to emit fluorescence photons, with a measurement interval being defined between each two successive excitation light pulses. A value characterizing fluorescence decay behavior is determined based on detection times of detected fluorescence photons, and imaging is performed based one the value. An analog detector signal is sampled within a plurality of sampling intervals within a respective one of the measurement intervals and is converted into a sequence of discrete signal values associated with the sampling intervals. It is determined based thereon whether more than a predefined number of fluorescence photons has been detected within the respective measurement interval.

Abstract: A fluorescence lifetime imaging microscopy method with time-correlated single photon counting includes periodically exciting a sample to emit fluorescence photons, with a measurement interval being defined between each two successive excitation light pulses. A value characterizing fluorescence decay behavior is determined based on detection times of detected fluorescence photons, and imaging is performed based one the value. An analog detector signal is sampled within a plurality of sampling intervals within a respective one of the measurement intervals and is converted into a sequence of discrete signal values associated with the sampling intervals. It is determined based thereon whether more than a predefined number of fluorescence photons has been detected within the respective measurement interval.

Abstract: An optical arrangement has an optical beam path for illuminating a sample space with a sequence of laser light pulses generated in a laser cycle, the optical arrangement. At least one laser light source is configured to generate the sequence of laser light pulses along the optical beam path. A wavelength-selective pulse picker is situated in the optical beam path and has, in a predefined illumination clock timing synchronizable with the laser light pulses, an open state in which the pulse picker is light-transparent to at least one laser light pulse towards the sample space. The open state has at least two different transmission states which differ with regard to their respective transmission spectrums, and wherein the two transmission states are switchable on and/or off independently of one another.

Abstract: A light/voltage converter circuit for converting intensity fluctuations of light into an alternating voltage measurement signal includes a photodiode configured to detect the light and a transformer comprising a primary coil and a secondary coil. The primary coil is connected in a series circuit to the photodiode, and the alternating voltage measurement signal is applied to the secondary coil. An electrical network is configured to block direct current and conduct alternating current. The electrical network is connected in parallel with the series circuit consisting of the primary coil of the transformer and the photodiode.

Abstract: An electric circuit for driving an acousto-optic crystal includes a piezoelectric converter configured to drive the acousto-optic crystal to vibrate mechanically. A signaling cable is configured to conduct a first electrical alternating-current signal and a second electrical signal. The electric circuit further includes a first frequency-separating filter and a second frequency-separating filter, each of the frequency-separating filters having an input, a high-frequency output and a low-frequency output. The input of the first frequency-separating filter and the input of the second frequency-separating filter is connected to the signaling cable, and the high-frequency output of the second frequency-separating filter is connected to the piezoelectric converter.

Abstract: The present invention relates to a method for measuring the lifetime of an excited state in a sample, in particular a fluorescence lifetime, and to an apparatus for carrying out such a method. First, an excitation pulse is generated and a sample region is illuminated with the excitation pulse. Then, a first digital data sequence is generated which is representative of the power-time profile of the excitation pulse, and a first switching instant is determined from the first digital data sequence. Moreover, the detection light emanating from the sample region is detected by a detector, and a second digital data sequence is generated which is representative of the power-time profile of the detection light, and a second switching instant is determined from the second digital data sequence. Finally, the time difference between the first and second switching instants is calculated.

Abstract: An arrangement for use in illuminating a sample in SPIM microscopy includes an illumination objective configured to receive and focus a light strip or a quasi-light strip. The quasi-light strip is made up of a light bundle continuously moved back and forth in a light-strip plane. A deflection apparatus is configured to deflect the light strip or the quasi-light strip, after the light strip or the quasi-light strip has passed through the illumination objective, in such a way that the light strip or the quasi-light strip propagates at an angle different from zero degrees with respect to an optical axis of the illumination objective. The illumination objective and the deflection apparatus are arranged movably relative to one another.