A low-cost high-repetition-rate picosecond laser diode pulse generator

Uhring, Wilfried; Zint, Chantal-Virginie; Bartringer, J.

doi:10.1117/12.545038

Cited by 34 publications

(24 citation statements)

References 3 publications

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“…The illumination is achieved using a 650 nm low power (5 mW) laser diode driven from a custom pulse generator using bipolar transistors [31]. Biasing the laser diode close to emission, we apply short current pulses to cause momentary population inversion and emit a laser pulse in the picosecond range.…”

Section: Histogramsmentioning

confidence: 99%

LinoSPAD: A Compact Linear SPAD Camera System with 64 FPGA-Based TDC Modules for Versatile 50 ps Resolution Time-Resolved Imaging

2017

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Abstract:The LinoSPAD camera system is a modular, compact and versatile time-resolved camera system, combining a linear 256 high fill factor pixel CMOS SPAD (single-photon avalanche diode) sensor with an FPGA (field-programmable gate array) and USB 3.0 transceiver board. This modularization permits the separate optimization or exchange of either the sensor front-end or the processing back-end, depending on the intended application, thus removing the traditional compromise between optimal SPAD technology on the one hand and time-stamping technology on the other hand. The FPGA firmware implements an array of 64 TDCs (time-to-digital converters) with histogram accumulators and a correction module to reduce non-linearities. Each TDC is capable of processing over 80 million photon detections per second and has an average timing resolution better than 50 ps. This article presents a complete and detailed characterization, covering all aspects of the system, from the SPAD array light sensitivity and noise to TDC linearity, from hardware/firmware/software co-design to signal processing, e.g., non-linearity correction, from power consumption to performance non-uniformity.

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Section: Histogramsmentioning

confidence: 99%

LinoSPAD: A Compact Linear SPAD Camera System with 64 FPGA-Based TDC Modules for Versatile 50 ps Resolution Time-Resolved Imaging

2017

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“…A picture of t The laser diode picosecond pulse generator used for this spectroscopic imaging device has been already described 15 . A wide diversity of laser diodes is available in the required NIR wavelength range, the diagnostic window, and the reported optical pulse widths are less than 80 ps FWHM.…”

Section: Descriptimentioning

confidence: 99%

“…A picosecond optical pulse generator has been realized: the printed circuit board includes four electrical generators which drive four laser diodes at 655, 785, 830 and 870 nm. The electrical pulse generators are adjusted to obtain the most powerful single picosecond optical pulse 15 . In order to have a single and common optical output whatever the wavelength, the four laser diode are coupled to a four-furcated optical fiber ended with a frontal light distributor to obtain a uniform illumination spot.…”

Section: Descriptimentioning

confidence: 99%

A time-gated near-infrared spectroscopic imaging device for clinical applications.

Poulet

Uhring²,

Hanselmann³

et al. 2013

SPIE Proceedings

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A time-resolved, spectroscopic, diffuse optical tomography device was assembled for clinical applications like brain functional imaging. The entire instrument lies in a unique setup that includes a light source, an ultrafast time-gated intensified camera and all the electronic control units. The light source is composed of four near infrared laser diodes driven by a nanosecond electrical pulse generator working in a sequential mode at a repetition rate of 100 MHz. The light pulses are less than 80 ps FWHM. They are injected in a four-furcated optical fiber ended with a frontal light distributor to obtain a uniform illumination spot directed towards the head of the patient. Photons back-scattered by the subject are detected by the intensified CCD camera. There are resolved according to their time of flight inside the head. The photocathode is powered by an ultrafast generator producing 50 V pulses, at 100 MHz and a width corresponding to a 200 ps FWHM gate. The intensifier has been specially designed for this application. The whole instrument is controlled by an FPGA based module. All the acquisition parameters are configurable via software through an USB plug and the image data are transferred to a PC via an Ethernet link. The compactness of the device makes it a perfect device for bedside clinical applications. The instrument will be described and characterized. Preliminary data recorded on test samples will be presented.

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“…We believe time-resolution can improve accuracy of newborns' brain monitoring under sensory stimulation and more specifically olfactory stimulation. Based on our experience of brain oxygenation monitoring under olfactory stimulation [7] and on time-resolved optical instrumentation development [8,9], we designed and developed a compact and robust instrumentation including harmless laser-diodes, single photon detection and counting module in order to be easily transportable into a clinical department. The first step of its technical validation is presented here, using phantoms.…”

Section: Introductionmentioning

confidence: 99%

A safe, low-cost, and portable instrumentation for bedside time-resolved picosecond near infrared spectroscopy

et al. 2009

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Continuous wave Near InfraRed Spectroscopy (NIRS) has been used successfully in clinical environments for several years to detect cerebral activation thanks to oxymetry (i.e. absorption of photons by oxy-and deoxy-hemoglobin) measurement. The goal of our group is to build a clinically-adapted time-resolved NIRS setup i.e. a setup that is compact and robust enough to allow bedside measurements and that matches safety requirements with human patients applications. Indeed our group has already shown that time resolution allows spatial resolution and improves sensitivity of cerebral activation detection. The setup is built with four laser diodes (excitation wavelengths: 685, 780, 830 and 870 nm) whose emitted light is injected into four optical fibers; detection of reflected photons is made through an avalanche photodiode and a high resolution timing module used to record Temporal Point Spread Functions (TPSF). Validation of the device was made using cylindrically-chaped phantoms with absorbing and/or scattering inclusions. Results show that recorded TPSF are typical both of scattering and absorbing materials thus demonstrating that our apparatus would detect variation of optical properties (absorption and scattering) deep within a diffusive media just like a cerebral activation represents a rise of absorption in the cortex underneath head surface.

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A low-cost high-repetition-rate picosecond laser diode pulse generator

Cited by 34 publications

References 3 publications

LinoSPAD: A Compact Linear SPAD Camera System with 64 FPGA-Based TDC Modules for Versatile 50 ps Resolution Time-Resolved Imaging

LinoSPAD: A Compact Linear SPAD Camera System with 64 FPGA-Based TDC Modules for Versatile 50 ps Resolution Time-Resolved Imaging

A time-gated near-infrared spectroscopic imaging device for clinical applications.

A safe, low-cost, and portable instrumentation for bedside time-resolved picosecond near infrared spectroscopy

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