Efficient astigmatic mode-converter based on spherical mirrors

Laguerre-Gaussian (LGmn) modes have several unique properties that lend them to applications in materials processing [1] and particle manipulation [2], among others. One characteristic that lends these modes to such applications is their ability to carry orbital angular momentum (OAM), as opposed to the spin angular momentum of beams that are circularly polarised. There are several techniques for creating these; one popular one exploits the Gouy phase shift through the use of cylindrical lenses [3]. The Gouy phase shift causes a phase shift in a Gaussian beam as it passes through a focus and is dependent on the Rayleigh range of the beam. Using cylindrical lenses to create an astigmatic focal point you can create a relative phase shift between the sagittal and tangential planes of the beam. As a LG01 can be modelled as two orthogonal first order Hermite-Gaussian (HG01) modes, π out of phase with each other, you can exploit this to convert between the two modes. Furthermore, depending on whether the HG01 mode is at +45° or -45° to the astigmatic axis it will create an LG01 mode with either clockwise or anticlockwise orbital angular momentum

Handedness of Laguerre-Gaussian LG₀₁ mode in a unidirectional ring laser

A single-frequency Nd:YAG ring laser operating on the Laguerre-Gaussian LG01 mode with well determined handedness of helical phase front is demonstrated. We show that by reversing the lasing direction the handedness can be changed

The role of laboratory investigation in the diagnosis and management of patients with suspected herpes simplex encephalitis: a consensus report. The EU Concerted Action on Virus Meningitis and Encephalitis.

As effective therapies for the treatment of herpes simplex encephalitis (HSE) have become available, the virology laboratory has acquired a role of primary importance in the early diagnosis and clinical management of this condition. Several studies have shown that the polymerase chain reaction (PCR) of CSF for the detection of herpes simplex virus type 1 (HSV-1) or type 2 (HSV-2) DNA provides a reliable method for determining an aetiological diagnosis of HSE. The use of PCR in combination with the detection of a specific intrathecal antibody response to HSV currently represents the most reliable strategy for the diagnosis and monitoring of the treatment of adult patients with HSE. The use of these techniques has also led to the identification of atypical presentations of HSV infections of the nervous system and permits the investigation of patients who develop a relapse of encephalitic illness after an initial episode of HSE. A strategy for the optimal use of the investigative laboratory in the diagnosis of HSE and subsequent management decisions is described