Linear array detector for online diagnostics of spectral distributions at MHz repetition rates

Gerth, Christopher; Brenner, Günter; Caselle, M.; Düsterer, S.; Haack, Daniel; Makowski, Dariusz; Mielczarek, Aleksander; Palutke, Steffen; Rota, Lorenzo; Rybnikov, V.; Schmidt, Christian; Steffen, B.; Tiedtke, K.

doi:10.1107/s1600577519007835

Cited by 11 publications

(11 citation statements)

References 17 publications

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“…The probe laser is reflected on a Gallium Phosphide (GaP) crystal back side. The spectrum readout is performed using a KALYPSO linear array camera operating at 1.13 MHz line rate 51 , 52 . Details of laser transport and KALYPSO focusing optics are not shown—see ref.…”

Section: Resultsmentioning

confidence: 99%

“…The spectra are recorded in single-shot, using a grating spectrometer based on the KALYPSO fast linear array detector 51 , 52 operated at a line rate of 1.13 MHz. A first series of electron bunch trains for one polarization is recorded and then the last half-wave plate before the polarizing beam splitter is rotated by π /8 to record the complementary polarization.…”

Section: Methodsmentioning

confidence: 99%

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Phase Diversity Electro-optic Sampling: A new approach to single-shot terahertz waveform recording

et al. 2022

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Recording electric field evolution in single-shot with THz bandwidth is needed in science including spectroscopy, plasmas, biology, chemistry, Free-Electron Lasers, accelerators, and material inspection. However, the potential application range depends on the possibility to achieve sub-picosecond resolution over a long time window, which is a largely open problem for single-shot techniques. To solve this problem, we present a new conceptual approach for the so-called spectral decoding technique, where a chirped laser pulse interacts with a THz signal in a Pockels crystal, and is analyzed using a grating optical spectrum analyzer. By borrowing mathematical concepts from photonic time stretch theory and radio-frequency communication, we deduce a novel dual-output electro-optic sampling system, for which the input THz signal can be numerically retrieved—with unprecedented resolution—using the so-called phase diversity technique. We show numerically and experimentally that this approach enables the recording of THz waveforms in single-shot over much longer durations and/or higher bandwidth than previous spectral decoding techniques. We present and test the proposed DEOS (Diversity Electro-Optic Sampling) design for recording 1.5 THz bandwidth THz pulses, over 20 ps duration, in single-shot. Then we demonstrate the potential of DEOS in accelerator physics by recording, in two successive shots, the shape of 200 fs RMS relativistic electron bunches at European X-FEL, over 10 ps recording windows. The designs presented here can be used directly for accelerator diagnostics, characterization of THz sources, and single-shot Time-Domain Spectroscopy.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Phase Diversity Electro-optic Sampling: A new approach to single-shot terahertz waveform recording

et al. 2022

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“…A direct measurement of the average photon energy variation across the burst is displayed in Fig. 2(b) , where an acquisition from an online spectrometer 26 equipped with the MHz line-detector KALYPSO 27 is shown.…”

Section: Methodsmentioning

confidence: 99%

Shot noise limited soft x-ray absorption spectroscopy in solution at a SASE-FEL using a transmission grating beam splitter

Engel

Ekimova

Miedema

et al. 2021

Structural Dynamics

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X-ray absorption near-edge structure (XANES) spectroscopy provides element specificity and is a powerful experimental method to probe local unoccupied electronic structures. In the soft x-ray regime, it is especially well suited for the study of 3 d -metals and light elements such as nitrogen. Recent developments in vacuum-compatible liquid flat jets have facilitated soft x-ray transmission spectroscopy on molecules in solution, providing information on valence charge distributions of heteroatoms and metal centers. Here, we demonstrate XANES spectroscopy of molecules in solution at the nitrogen K -edge, performed at FLASH, the Free-Electron Laser (FEL) in Hamburg. A split-beam referencing scheme optimally characterizes the strong shot-to-shot fluctuations intrinsic to the process of self-amplified spontaneous emission on which most FELs are based. Due to this normalization, a sensitivity of 1% relative transmission change is achieved, limited by fundamental photon shot noise. The effective FEL bandwidth is increased by streaking the electron energy over the FEL pulse train to measure a wider spectral window without changing FEL parameters. We propose modifications to the experimental setup with the potential of improving the instrument sensitivity by two orders of magnitude, thereby exploiting the high peak fluence of FELs to enable unprecedented sensitivity for femtosecond XANES spectroscopy on liquids in the soft x-ray spectral region.

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“…Analysis of data captured in the EuXFEL is provided in a separate publication [4]. Evaluation of the KALYPSO detector is provided in the papers [11,17].…”

Section: Evaluation Of Holdmentioning

confidence: 99%

Real-Time Data Acquisition and Processing System for MHz Repetition Rate Image Sensors

et al. 2021

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An electro-optic detector is one of the diagnostic setups used in particle accelerators. It employs an electro-optic crystal to encode the longitudinal beam charge profile in the spectrum of a light pulse. The charge distribution is then reconstructed using data captured by a fast spectrometer. The measurement repetition rate should match or exceed the machine bunching frequency, which is often in the range of several MHz. A high-speed optical line detector (HOLD) is a linear camera designed for easy integration with scientific experiments. The use of modern FPGA circuits helps in the efficient collection and processing of data. The solution is based on Xilinx 7-Series FPGA circuits and implements a custom latency-optimized architecture utilizing the AXI4 family of interfaces. HOLD is one of the fastest line cameras in the world. Thanks to its hardware architecture and a powerful KALYPSO sensor from KIT, it outperforms the fastest comparable commercial devices.

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Linear array detector for online diagnostics of spectral distributions at MHz repetition rates

Cited by 11 publications

References 17 publications

Phase Diversity Electro-optic Sampling: A new approach to single-shot terahertz waveform recording

Phase Diversity Electro-optic Sampling: A new approach to single-shot terahertz waveform recording

Shot noise limited soft x-ray absorption spectroscopy in solution at a SASE-FEL using a transmission grating beam splitter

Real-Time Data Acquisition and Processing System for MHz Repetition Rate Image Sensors

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