Targeted pruning of a neuron's dendritic tree via femtosecond laser dendrotomy.

Neurons are classified according to action potential firing in response to current injection. While such firing patterns are shaped by the composition and distribution of ion channels, modelling studies suggest that the geometry of dendritic branches also influences temporal firing patterns. Verifying this link is crucial to understanding how neurons transform their inputs to output but has so far been technically challenging.

Simultaneous multi-site two-photon photostimulation in three dimensions.

We demonstrate simultaneous multi-site two-photon photolysis of caged neurotransmitters with close to diffraction-limited resolution in all three dimensions (3D). We use holographic projection of multiple focal spots, which allows full control over the 3D positions of uncaging sites with a high degree of localized excitation. Our system incorporates a two-photon imaging setup to visualize the 3D morphology of the neurons in order to accurately determine the photostimulation sites.

Optimal complex field holographic projection.

We describe a technique that uses complex field holograms to project three-dimensional light patterns. Holographic projection commonly uses phase-only encoding since accurately representing complex holograms using both amplitude and phase spatial light modulators reduces the optical throughput significantly. Here, we use a lossless projection via the generalized phase contrast method to produce the necessary amplitude pattern required for complex field holographic projection.

Optical trapping and surgery of living yeast cells using a single laser.

We present optical trapping and surgery of living yeast cells using two operational modes of a single laser. We used a focused laser beam operating in continuous-wave mode for noninvasive optical trapping and manipulation of single yeast cell. We verified that such operational mode of the laser does not cause any destructive effect on yeast cell wall.

Holographic projection of arbitrary light patterns with a suppressed zero-order beam.

We present what is to our knowledge a novel technique for efficient suppression of the zero-order beam inherent in light patterns projected via phase-only computer-generated holograms (CGHs). Encoding a CGH on a spatial light modulator (SLM) with a limited fill factor produces a disturbing zero-order beam at the optical axis. Here, we propose to derive a CGH, which includes holographic information to project a corrective beam that destructively interferes with the zero-order beam.

Effect of spurious diffraction orders in arbitrary multifoci patterns produced via phase-only holograms.

We analyze the effect of spurious diffraction orders when generating functional multifoci patterns produced by illuminating a phase-only hologram with a single Gaussian beam. Using a practical device for encoding a hologram generates an undesirable zero order and high-diffraction orders at the Fourier plane. This translates to the fact that a significant fraction of the incident light does not necessarily convert to functional multifoci patterns.

Real-time three-dimensional optical micromanipulation of multiple particles and living cells.

Counterpropagating light fields provide a stationary optical potential well for a Brownian particle. Introducing variability in the relative strengths of the counterpropagating beams allows us to create a more general configuration-the optical elevator. An optical elevator dynamically controls the axial location of the potential minimum where the particle finds a stable equilibrium position.

Reply to comment on "Excitation with a focused, pulsed optical beam in scattering media: diffraction effects.".

We address the issues that were raised by Tycho and Jørgensen [Appl. Opt. 41, 4709 (2002)] concerning our strategy [Appl.