A jaw assembly including first and second jaw members configured to clamp tissue therebetween. The first jaw member includes a surface opposing a surface of the second jaw member, a light source, and a light detector. The light source is configured to emit light from an opening defined in the surface of the first jaw member. The light detector is disposed within the opening and is configured to sense properties of light reflected off tissue clamped between the first and second jaw members and to generate signals indicative of the sensed properties of light. A processor is operatively associated with the light detector and is configured to receive the signals from the light detector. The processor is also configured to analyze the signals to determine an attribute of tissue clamped between the first and second jaw members and to provide feedback to a user of the attribute of the tissue.

Instrument for optically detecting tissue attributes

We present a general theory of spin-to-orbital angular momentum (AM) conversion of light in focusing, scattering, and imaging optical systems. Our theory employs universal geometric transformations of non-paraxial optical fields in such systems and allows for direct calculation and comparison of the AM conversion efficiency in different physical settings. Observations of the AM conversions using local intensity distributions and far-field polarimetric measurements are discussed.

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Spin-to-orbital angular momentum conversion in focusing, scattering, and imaging systems

In this Letter we present the first (to our knowledge) demonstration of material modification using tightly focused single femtosecond laser vortex pulses. Double-charge femtosecond vortices were synthesized with a polarization-singularity beam converter based on light propagation in a uniaxial anisotropic medium and then focused using moderate- and high-NA optics (viz., NA=0.45 and 0.9) to ablate fused silica and soda-lime glass. By controlling the pulse energy, we consistently machine micrometer-size ring-shaped structures with <100nm uniform groove thickness.

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Materials processing with a tightly focused femtosecond laser vortex pulse

This letter is the first demonstration of material modification using tightly focused femtosecond laser vortex beams. Double-charge femtosecond vortices were synthesized with the polarization-singularity beam converter described in Ref [1] and then focused using moderate and high numerical aperture optics (viz., NA = 0.45 and 0.9) to ablate fused silica and soda-lime glasses. By controlling the pulse energy we consistently machine high-quality micron-size ring-shaped structures with less than 100 nm uniform groove thickness.

Materials processing with a tightly focused femtosecond vortex laser pulse

Stimulated emission depletion (STED) microscopy usually employs a scanning excitation beam that is superimposed by a donut-shaped STED beam for keeping the fluorophores at the periphery of the excitation spot dark. Here, we introduce a simple birefringent device that produces a donut-shaped focal spot with suitable polarization for STED, while leaving the excitation spot virtually intact. The device instantly converts a scanning (confocal) microscope with a co-aligned STED beam into a full-blown STED microscope. The donut can be adapted to reveal, through the resulting fluorescence image, the orientation of fluorophores in the sample, thus directly providing subdiffraction resolution images of molecular orientation.

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Birefringent device converts a standard scanning microscope into a STED microscope that also maps molecular orientation.

The vectorial Debye integral shows that tightly focused Laguerre-Gaussian (LG) beams have a residual intensity at the focal point for linear polarization, for a topological charge of m=1 and 2. We measured the shapes of linearly and circularly polarized LG beams and found that a central intensity appeared at m=1 and 2 for linear and right-handed circular polarization, however, it is completely canceled for left-handed circular polarization. In general, when the orbital angular momentum of the LG beam is parallel to the spin angular momentum of the photons, zero intensity is always achieved at the focus.

Investigation of the center intensity of first- and second-order Laguerre-Gaussian beams with linear and circular polarization

PROBLEM TO BE SOLVED: To employ a PPD as a detector, and to allow users to easily determine a saturation level of an optical detector varying with a modification of an observation condition.SOLUTION: A laser microscope device 1 is provided that comprises: a scanning unit 6 that scans laser light L on a sample S; an objective lens 8 that converges observation light L' occurring in the sample S; an optical detection unit 14 that has a light reception surface 14a composed by having a plurality of detection elements capable of detection of a single photon arrayed on a plane, receives the observation light L' converged by the objective lens 8 and incident upon the light reception surface 14a, and outputs an intensity signal having intensity in accordance with an amount of light of the observation light L'; an image creation unit 32 that creates an image of the sample S on the basis of the intensity of the intensity signal and a scanning position of the laser light L; and recognition means 33 that, when the intensity signal having intensity equal to or more than a prescribed threshold is included in intensity signal to be used in the creation of the image, makes users recognize to the effect that the intensity signal is included therein, in which the prescribed threshold is set in accordance with a beam diameter of the observation light L' to be incident upon the light reception surface 14a.SELECTED DRAWING: Figure 1

Laser microscope device

We constructed a super-resolution microscope system based on a cw laser light source. Electro-optical modulators convert the cw laser light into a light pulse with a width of 15ns and provide a repetition rate of 100kHz. The performance of the microscope was evaluated using 100nmϕ fluorescence microbeads. The fluorescence signal from the beads can be detected with very low statistical fluctuation. The super-resolution image was obtained with better signal to noise ratio compared with that given by a pulse laser light source with a repetition rate of several tens of hertz. The fluorescent size of the beads was 150nm, which is 2.3 times smaller than the diffraction limit. Experimental results confirmed that the two-point resolution also overcomes the diffraction limit. The constructed system is expected to become a commercial microscope.

Construction of super-resolution microscope based on cw laser light source

[PROBLEMS] To provide an ultra-high resolution microscope in which the light source of pumping light and erase light can be selected easily and ultra-high resolution can be reliably exhibited through a simple and inexpensive arrangement. [MEANS FOR SOLVING PROBLEMS] In the ultra-high resolution microscope, optical systems (3, 4, 9) combines a part of a first coherent light from a first light source (2) and a part of a first coherent light from a second light source (1) and focuses the coherent lights onto a sample (10), scanning means (6, 7) scans the coherent lights, and detecting means (6, 7) detects an optical response signal from the sample (10). Following relations are satisfied: σ01Ipτ≤1 and 0.65(λe/λp)≤τσdipIe where the wavelength of first coherent light is λp, the wavelength of second coherent light is λe, maximum photon flux on the sample surface of the first coherent light is Ip, the maximum photon flux on the sample surface of the second coherent light is Ie, the absorption cross-sectional area when a molecule is excited from the ground state to a first electron excited state is σ01, and the fluorescence suppression cross-sectional area is σdip.

Takeshi Watanabe

Papers

Investigation of the center intensity of first- and second-order Laguerre-Gaussian beams with linear and circular polarization

Laser microscope device

Construction of super-resolution microscope based on cw laser light source

Ultra-high resolution microscope

Analysis of a fluorescence depletion process of Rhodamine 6G in a PMMA matrix induced by nano- and picosecond lasers