2-Photon imaging has dramatically expanded its reach in neuroscience-related applications thanks to the development of genetically encoded functional probes that report cellular activity and activates/silence individual neurons (optogenetics). The combination of 3D spatial resolution afforded by 2-photon imaging and the proliferation of advanced scanning and scanless methodologies enable powerful parallel functional imaging of thousands of individually selected neurons.
Faster and parallel imaging of large cell populations requires femtosecond lasers with higher average power and energy, but also improved pulse-to-pulse stability all along the required tuning ranges.
Light Conversion has pioneered the development of femtosecond wavelength-tunable devices as well as of high-energy and -power Ytterbium lasers ad amplifiers. In this presentation we highlight how these developments are powering advanced imaging techniques using reporting and optogenetic probes.
Ultrafast laser sources are a key enabling technology for nonlinear excitation in multiphoton microscopy. Rapid developments in the last five years have realized a wider scope of laser platforms that address emerging opportunities for (pre)clinical applications in nonlinear microscopy, along with additional optical functionality such as integrated power modulation options and higher energy regimes that enable deeper imaging via 3-photon excitation. In this presentation we will review the latest developments in ultrafast lasers and their impacts in the field of nonlinear microscopy.
We review the status of commercially available USP (ultra short pulse) laser amplifiers and their key components, analyzing how technology innovation and industrial/scientific applications are pushing boundaries in performance and reliability. These improvements will be instrumental in facilitating adoption in challenging environments like defense applications. We provide examples of performance requirements for various applications and describe the challenges to overcome to increase performance and reliability of fielded USP lasers and amplifiers.
The performance of advanced laser systems for defense and aerospace applications rely heavily on the capabilities of the system building blocks. Due to the sensitive nature of the end applications, such components also often require domestic US sources to ensure supply chain security and facilitate engagement in the product development cycle.
Coherent maintains a full range of domestic critical component manufacturing capabilities to support the defense and aerospace laser industry, including optical fiber, semiconductor diode lasers, crystals, optical isolators, coatings and freeform optics, all from US-based manufacturing locations.
Coherent has also expanded the internal manufacturing capabilities, enabling the manufacture of complete laser component assemblies and subsystems, allowing contract partners to leverage our internal laser manufacturing expertise. We will review our latest component capabilities and discuss how these components map to critical defense applications.
Multiphoton microscopy is used in diverse branches of biology. While its main applications are related to neuroscience, cancer and stem cell research take advantage of this imaging technique. In addition, the push to use multi-photon imaging for clinical and even diagnostic applications is gaining momentum both on the research and commercial front.
This broad range of applications requires diverse types of femtosecond laser sources - compact, dedicated and portable on one side, and flexible and very high-performance on the opposite end. In this talk we will discuss recent developments in laser technology addressing these various requirements.
We discuss the key trends in two and three photon microscopy driving new laser technologies. When distilled, these trends are moving down three paths, for mainstream, tunable 2 photon excitation sources, advanced high energy sources for especially for brain imaging and compact, fixed wavelength OEM friendly lasers.
The invention of Multiphoton excitation microscopy took place 30 years ago. The tremendous success and proliferation of applications related to this non-linear imaging modality resulted in the development of femtosecond tunable lasers specifically designed to address varieties of probes and optical set-ups. Recent innovations like three-photon imaging, optogenetics activation of many neurons and new approaches towards diagnostic applications fostered an even more rapid pace of innovation resulting in laser sources producing high energy tunable pulses and compact, dedicated and cost-effective sources. We will describe these new sources and how they fit diverse applications within Multiphoton excitation Microscopy
Functional non-linear imaging has become an essential tool to improve our understanding of how the brain works. Progress in neuroscience tools like functional probes and opsins, as well as novel imaging approaches using SLMs or adaptive optics enables to study hundreds or thousands of neurons at speeds matching the typical brain’s activity patterns. Studies in immunology and disease states on the other hand use more conventional lasers parameters and imaging tools, and benefit from a deeper integration of the laser with the microscope. In this presentation we will describe new generation lasers specifically designed to address the most advanced imaging needs in these two all-important areas. We will describe novel sources for functional brain imaging and optogenetics, based on Ytterbium fiber laser media that produce tens of watts of average power, energy per pulse of tens of microjoule at 1035 nm and unparalleled flexibility in repetition rate. Such high average powers/energies are necessary to stimulate large neuron populations when used for time interval shorter than the onset of cell damage; they can also be used to pump one or more wavelength conversion devices like OPAs and OPCPA used for 3-photon imaging and for fast volumetric Ca imaging. Application to stem cell research or disease states are generally less demanding in power and energy but requirements for high throughput and high quality images requires lasers tools that are more deeply integrated with the microscope providing fast dispersion and power management. In this presentation we will describe the state of the art of these different types of laser sources.
Multiphoton microscopy has become an ubiquitous research tool for neuroscience, disease studies, embryology and immunology. Refinements in non-linear imaging techniques have gone hand-in-hand with improvements in tuning range, power, pulse management and other features of femtosecond lasers specifically designed for these applications. While potential clinical applications require lasers with multiple outputs able to support multimodal imaging, recent developments in neuronal imaging like 3-photon microscopy or optogenetic activation require higher energies per pulse and longer wavelengths than conventional multiphoton microscopy. Here we describe the design and characteristics of laser sources able to address all these applications, staring with the more established ultrafast laser technology based on Titanium Sapphire lasers and their OPOs and covering recently developed sources like Ytterbium fiber mode-locked lasers and amplifiers with their tunable wavelength extensions.
In the last few years Multiphoton Excitation Microscopy witnessed a mutation from tool for imaging cellular structures in living animals deeper than other high-resolution techniques, into an instrument for monitoring functionality and even stimulating or inhibiting inter-cellular signalling. This paradigm shift has been enabled primarily by the development of genetically encoded probes like Ca indicators (GECI) and Opsins for optogenetics inhibition and stimulation. These developments will hopefully enable the understanding of how local network of hundreds or thousands of neurons operate in response to actual tasks or induced stimuli. Imaging, monitoring signals and activating neurons, all on a millisecond time scale, requires new laser tools providing a combination of wavelengths, higher powers and operating regimes different from the ones traditionally used for classic multiphoton imaging. The other key development in multiphoton techniques relates to potential diagnostic and clinical applications where non-linear imaging could provide all optical marker-free replacement of H and E techniques and even intra-operative guidance for procedures like cancer surgery. These developments will eventually drive the development of specialized laser sources where compact size, ease of use, beam delivery and cost are primary concerns. In this talk we will discuss recent laser product developments targeting the various applications of multiphoton imaging, as fiber lasers and other new type of lasers gradually gain popularity and their own space, side-by-side or as an alternative to conventional titanium sapphire femtosecond lasers.
We report on multiphoton imaging of biological samples performed with continuum infrared source generated
in photonic crystal fibers (PCFs). We studied the spectra generated in PCFs with dispersion profiles designed
to maximize the power density in the 700-1000 nm region, where the two-photon absorption cross sections of
the most common dyes lie. Pumping in normal dispersion region, with <140 femtosecond pulses delivered by a
tunable Ti:Sa laser (Chameleon Ultra II by Coherent Inc.), results in a limitation of nonlinear broadening up to a
mean power density above 2 mW/nm. Axial and lateral resolution obtained with a scanning multiphoton system
has been measureed to be near the theoretical limit. The possibility of simultaneous two-photon excitation of
different dyes in the same sample and high image resolution are demonstrated at tens of microns in depth.
Signal-to-noise ratio and general performances are found to be comparable with those of a single wavelength
system, used for comparison.
We describe the realization and characterization of a broadband, high power density and fully spectrally controllable
source, suitable for multiphoton imaging of biological samples. We used a photonic crystal fiber (PCF)
with selected dispersive and non-linear properties, in order to generate, when pumped with <140 femtosecond
pulses delivered by a tunable Ti:Sa laser (Chameleon Ultra II by Coherent Inc.), a smooth continuum in the
700nm-950nm region, with average power density grater than 2mW/nm. Time distribution of the generated
spectrum has been measured with autocorrelation technique. Axial and lateral resolution obtained with a scanning
multiphoton system has been determined to be near the theoretical limit. The possibility of two-photon
excitation of different dyes in the same sample and high image resolution are demonstrated at tens of microns
in depth. Future developments and different applications are also discussed.
Water-cooled ion lasers have been commercially available for 25 years. Since the introduction of the metal-ceramic plasma tube technology 10 years ago, a considerable amount of research and development activity at Coherent has been devoted to improving the operating life and reliability of this kind of tube. The efficient generation of laser radiation imposes stringent requirements on the discharge parameters and, consequently, on the plasma tube itself. We have developed various methods to analyze the discharge environment, test the effectiveness of new materials and tube designs, and control the manufacturing process. The combined use of these methods allows the production of tubes with lifetimes that can exceed 10,000 hours in the visible wavelengths and 5,000 hours in the ultraviolet.
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