A pockels cell with a broken crystal

In a 2P microscope, pockels cells are employed for fast control of the laser beam intensity. I use it for both switching off the laser beam during turnarounds of the resonant scanner, between two frames if they are not immediately one after the other, and to adjust the beam intensity when scanning in z for multi-plane imaging. In total, the pockels cell is quite essential for me. Alternatively, people use mechanical shields to blank the beam during the turnaround, or slow motorized rotating λ/2-plates to adjust the laser intensity on a timescale of seconds.

Recently, I found out how a defect pockels cell can look like. For comparison, the first video shows a properly working pockels cell, although the refractive index-matching liquid inside might be a little bit low. The air-liquid interface can be clearly seen at some points.

In the second video, the crystal inside the pockels cell is clearly broken and therefore visible. This could be clearly seen immediately when looking at the laser beam, which was strongly diffracted after passing the pockels cell.

This defect occured most likely when the cell driver remained switched on for an extended period of time, with the offset voltage being set to a rather high value. So this happened due to the permanent voltage applied to the crystal, and not due to the pulsed laser intensity.

This article comes from ptrrupprecht edit released

Definition of Organic Scintillators

The scintillation in organic scintillators is due to the transitions between energy levels in a single molecule. These scintillators avoid the need for a regular crystal lattice structure. In organic scintillator molecules, the energy spacing the vibrational modes is 0.15eV and between the levels S0 and S1 is 3eV. Excitation of molecule from the ground state to the higher states occurs when energy is stored in the scintillator by a charged particle. Phosphorescence is emitted when the molecule is transferred from the S1 state to the T1 state.

A bulk solvent is added to the organic scintillant at small concentrations and the mixture is exposed to ionizing radiation. Light is emitted when the energy absorbed by the solvent is transferred to the scintillant.

Liquid scintillation counting is one of the challenging applications of organic scintillators in the field of nuclear medicine. In this technique, the scintillator used is a liquid dissolved with the radioactive sample to be assayed. The activity of low energy β-emitting radionuclides like 14C and 3H can be measured using this method.

This article comes from azosensors edit released

Nonlinear crystal phase matching

We offer a wide selection of nonlinear crystal phase matching. Various nonlinear crystal phase matching including Lithium Triborate (LBO), Beta Barium Borate (BBO), Potassium Titanyl Phosphate (KTP), Potassium Dihydrogen Phosphate & Potassium Dideuterium Phosphate (KDP & DKDP), Lithium Iodate (LiIO3), Lithium Niobate (LiNbO3) and infrared nonlinear crystal phase matching (AgGaS2, AgGaSe2, GaSe, ZnGeP2) with given standard sizes and orientations are available for fast off-the-shelf delivery.

However inquiries for custom made nonlinear optical crystal are also welcome. Nonlinear crystal phase matching are used in wide range of optical frequency conversion applications including laser harmonic generations (SHG, THG, 4HG), sum or difference frequency generation (SFG, DFG) and optical parametric generation, amplification or oscillation (OPG, OPA, OPO). Some nonlinear crystals for instance DKDP, BBO and KTP also possess electro-optical properties which make them useful for electro-optical applications – Q-switching or electro-optical amplitude modulation.

This article comes from eksmaoptics edit released

New generation of organic scintillation materials

We have designed and produced the next generation of organic scintillation materials.

The are organic polycrystals obtained from finely ground perfect single crystal by the pressing technology and organic composite scintillators obtained by introduction of crystalline grains into an optically transparent polymer base. The scintillation characteristics of proposed scintil-lation materials as detectors for short-range ionizing radiation and fast neutrons are discussed.

This technology is the base for production large area detectors which can be used in facilities for environmental radiation control, for security purposes (i.e. to prevent the forbidden entry of fission materials), for physical experiments, and in other branches of science and technol-ogy.

This article comes from researchgate edit released

Synthesis, Crystal Structure and Nonlinear Optical Crystals Property of RbHgI3

Searching for new nonlinear optical crystals to be used in the infrared (IR) region is still a challenge. This paper presents the synthesis, crystal structure and properties of a new halide, RbHgI3.

Its non-centrosymmetric single crystal can be grown in solution. In its crystal structure, all the polar [HgI4]2− groups align in such a way that brings a favorable net polarization. The measurement by Kurtz–Perry powder technique indicates that RbHgI3 shows a phase-matchable second harmonic generation (SHG) property seven times stronger than that of KH2PO4 (KDP).

RbHgI3 displays excellent transparency in the range of 0.48–25 μm with relatively good thermal stability. The UV absorption implies that this yellow compound’s band gap is about 2.56 eV, close to that of AgGaS2. A preliminary measurement indicates that the laser-induced damage threshold of the crystal is about 28.3 MW/cm2.

These preliminary experimental data reveal that RbHgI3 is a new candidate as nonlinear optical material in the infrared region.

This article comes from mdpi edit released

Gallium Arsenide Lenses

GaAs lenses is semi insulator, which can be used in large power continuous CO2 laser system to replace the zinc sulfide in lens or mirror forms. GaAs lenses is suitable in applications consists of toughness and durability.

In some cases, particles of dust or steel will impact the optical element surface, the hardness and strength of GaAs lenses surface makes it a good choice under such circumstance.

GaAs lenses was originally intended for use in semiconductor applications (rather than optical applications), and therefore, it is extremely important to make careful screening of materials in the manufacture of high quality GaAs lenses optical components.

GaAs lenses optical elements are subject to the restriction of crystal growth technology, the diameter is generally below 10 cm. The materials are hygroscopic and can be safely used in laboratory and field application, its chemical properties are very stable (except contact with strong acids)

When handling optics, one should always wear gloves. This is especially true when working with Gallium arsenide components, as it is a hazardous material. For your safety, please follow all proper precautions, including wearing gloves when handling these lenses and thoroughly washing your hands afterward.

This article comes from hypoptics edit released