GGG crystal wafers and Substrates

● Fine mechanical, optical and chemical properties
● Excellent as optical, microwave isolator and HTS substrates

GGG crystal wafers is material with good optical, mechanical and thermal properties which make it promising for use in fabrication of various optical components as well as substrate material for magneto – optical films and high – temperature superconductors. It can be used for infrared optical isolator (1.3 and 1.5 um), which is made of YIG or BIG film on the Gadolinium Gallium Garnet (GGG) substrate plus birefringence parts. GGG crystal wafers is an important substrate for microwave isolators and can be used as a HTS material, for laser technology, telecommunications, electronic.

A Small-Animal PET System Based on LYSO Crystal Arrays

A positron emission tomography system for small animals has been designed for research purposes. Its detection modules are based on pixelated scintillator LYSO crystal arrays coupled to Hamamatsu H8500 position-sensitive photomultiplier tubes. The front-end electronics are based on nuclear instrumentation modules (NIM) and in-house built readout circuits. Peak signal digitization is performed with a commercial analogue-to-digital acquisition (DAQ) board.

The system has been characterized for spatial, timing and energy resolution, system dead time, absolute sensitivity, scatter fraction and noise equivalent count rate (NEC).

The results indicate that the detection modules are able to identify individual crystals (out of 400) with up to 8-to-1 peak-to-valley ratios with individual crystal energy resolution ranging from 7 to 15% at 511 keV. The timing resolution is 1.9 ns and the system dead time was found to be 16.8 ¿s and 42.1 ¿s for 0.5 ml and 10 ml volume sources, respectively. The measured absolute system sensitivity is 0.11% and the scatter fraction from a glass capillary inside a 2.5 cm diameter mouse phantom is 21.5%. A true NEC maximum value was not achieved with the system due to saturation of the PS-PMT output signals for activities above 0.27 mCi. Results from a Na18 F PET bone scan of a 30 g mouse are shown.

This article comes from ieeexplore edit released

Intracavity PPLN crystals for ultra-low-voltage laser Q-switching and high-efficiency wavelength conversion

We report to the best of our knowledge the lowest switching voltage in an electro-optically Q-switched Nd:YVO4 laser by using a 13-mm long, 14-μm-period PPLN crystal as a Pockels cell. A switching voltage as low as ∼50 V in the PPLN crystal was sufficient to hold off the lasing of the Q-switched laser at a pump power more than two times above its continuous-wave threshold. When the PPLN Q-switch was driven by a 100-V voltage at 6.5 kHz, we obtained 0.9-kW laser peak power from this 1-W diode-pumped Nd:YVO4 laser system with 13% output coupling. When the PPLN Pockels cell was cascaded with a 5-cm long, 30-μm-period PPLN crystal, we produced ∼μJ/pulse energy at 1.59 μm from optical parametric generation inside the actively Q-switched laser.

This article comes from springer edit released

General properties of CdWO4 scintillator

Cadmium Tungstate (CdWO4) is a scintillation crystal with extremely low afterglow, good radiation resistance, high density and high Z value, low decay time also with relatively high light output.

CdWO4 scintillators was produced by using the Bridgman technique since 2011, with the maximum crystal boule size at ∅ 80 mm x 200 mm, which can be manufactured into the target sizes, besides the single crystals, we also have the capability to fabricate it into linear or 2 dimensional array used in the X ray security inspection systems.

CdWO4 scintillators is characterized by high density, high atomic number and relatively high light yield with extremely low decay time. and the afterglow of CdWO4, when subjected to x-ray irradiation, is very slow typically less than 0.1% after 3 ms, and demonstrate very good resistance. All of these features are significant and make CdWO4 a primary scintillation crystal for X ray computed Tomography(X-CT) and in security inspection.

This article comes from epic-crystal edit released

Germanium Lenses

Our Germanium lenses are perfect for Mid-Infrared applications. These lenses stand up well to harsh environments and we offer the most popular sizes with Anti-Reflection Coatings. Germanium is subject to thermal runaway, meaning that the transmission decreases as temperature increases. As such, these lenses should be used at temperatures below 100°C. Germanium’s high density (5.33 g/cm3) should be considered when designing for weight-sensitive systems. The Knoop Hardness of Germanium is 780, making it ideal for IR applications requiring rugged optics.

GERMANIUM LENSES

  • High Index of Refraction
  • Minimal Chromatic Aberration Due to Low Dispersion
  • Perfect for Rugged IR Applications
  • Popular Sizes Available with AR Coating from 3-12μm

Factory Standard– Contact us for manufacturing limit or custom specifications

  • Substrate Material: Ge (Germanium)
  • Diameter:  5mm-350mm
  • Shape: Spherical Plano-Concave, P-Convex, Concave-Convex or Aspheric
  • Focal length: +/-1%
  • Surface Quality: 20-10(after coating)
  • Surface figure: l/4 @ 633nm
  • Clear Aperture: >85% of central dimension
  • Antireflection Coating: @ 3-12 um

Further study of CdWO4 crystal scintillators as detectors for high sensitivity double beta experiments

Energy resolution, light yield, non-proportionality in the scintillation response, alpha/beta ratio, pulse shape for gamma rays and alpha particles were studied with CdWO4 crystal scintillators.

Some indication for a difference in the emission spectra for gamma rays and alpha particles was observed. No dependence of CdWO4 crystal pulse shape on emission spectrum wavelengths under laser, alpha particles and gamma ray excitation was observed.

Dependence of scintillation pulse shape for gamma quanta and alpha particles and pulse-shape discrimination ability on temperature was measured in the range of 0-24 degrees.

This article comes from arxiv edit released

Crystal growth of strontium titanate SrTiO3

SrTiO3 crystals have been prepared by flame-fusion growth and from KF-LiF and K-Li-borate fluxes.

The crystals are characterized by EPR, absorption spectra, chemical analyses and 7-rocking curves, and the structural perfection of flame-fusion and flux-grown crystals is compared.

This article comes from tandfonline edit released

UV Range Stepped Neutral Density on fused silica for full uv range control

We custom and standard neutral density optical filters for a wide spectrum of applications. These include machine vision, HPLC, gas chromatography, instrument calibration and flourescence microscopy.

Our online catalog continues to grow. The listed bandpass, longpass, shortpass, and neutral density optical filters are just a few in our expanding inventory. Please call or email us if you don’t see the filter you need. Our goal is to provide you with a perfect filter solution for your product or research project.

Our flexibility to run small prototype lots and custom setups at low cost have helped companies develop their products using our neutral density optical filters.

This article comes from maierphotonics edit released

Crystal optics

Compared to the previous options, this product has many benefits that far outweigh its failings. In our opinion, this is the best solution to go for when choosing IR Windows optics.

There are many different types of crystal IR Window materials. The most common being germanium. This material is found on your infrared camera lens and can either be purple or orange in colour, depending on the coating that has been used.

Germanium is known in the industry as the ‘grey transmitter’, which means that its transmission loss is consistent across the whole of the infrared spectrum. This factor makes it fantastic for lenses as it modulates the IR signal the same way regardless of wavelength. Also, the addition of anti-reflective coatings (AR) makes windows manufactured from this material extremely good infrared transmitters. Unfortunately, germanium can be expensive, and using this material to manufacture a 4″ IR Window would mean they would would end up retailing over $2000 per unit, which rules it out.

Another material which can be used is sapphire, which is very durable and would be able to withstand a hammer impact. But, similar to germanium, this is still a very costly material.

This leaves two materials, which are both ‘flourides’ – Calcium Flouride (CAF2) and Barium Flouride (BAF2). Both of which have been used as optics in the past, but although BAF2 is highly transmissive and great for measurement, it can also be susceptible to moisture and somewhat toxic.

CAF2 is the least expensive option here and is the optimum IR Window optic material. Although it can be brittle, properly coated CAF2 optics do not degrade over time and any errors in reading caused by the optic can be corrected reliably and repeatedly with a properly configured infrared camera. Taking all of this into consideration, we prefer HydroGARD coated CAF2 over the other options as the positives far outweigh the negatives.

Carbon Flouride is homogenous, meaning that its transmission characteristics are consistent across the face of the IR Window. This means that a properly configured IR camera can correct any errors and provide the thermographer with a truly representative temperature measurement. This material is also optically and thermally transparent and is not only transmissive to IR and visual cameras, but to UV cameras as well.

This article comes from cord-ex edit released

Cleaning Germanium Lenses: Choosing the Best Method

Cleaning germanium lenses elements improves performance, providing proper materials, techniques and handling procedures are used to minimize the risk of damage.

CVI LASER OPTICS

Optics can be contaminated in many ways. Contamination can be kept to a minimum by returning the optics to their case after use or by covering the optics for protection from the outside environment. However, even with all these precautions, the optic will eventually accumulate dust, stains or some other form of contamination.

Inspection of germanium lenses surfaces

During inspection, all optics must be handled in the cleanest area available (preferably a cleanroom or within a laminar flow bench). Proper equipment, such as powder-free cleanroom gloves or finger cots must be worn at all times to avoid grease and oils from being transferred to the optic. Lens tissue paper, dust-free blowers, hemostats, cotton swabs, cotton tips, and reagent-grade acetone and methanol, will all be needed for cleaning optics. The acetone and methanol must be fairly fresh to avoid leaving any marks on the optics. Reagent-grade isopropyl alcohol can also be used instead of acetone.

Pro Tip: Clean optics against a dark background so dust can be seen and eliminated more efficiently.

There are two ways in which an optic can be evaluated:

• If the optic is being used in a laser-based system, contamination on the optic might cause the optic to scatter the laser light, thus reducing power and making the optic “glow.”

• An optic can also be visually inspected by holding it below a bright light source and carefully viewing it at different angles. This will cause the light to scatter off the contamination enabling the viewer to see the various stains and dust particles.

Cleaning methods

1) Blowing method
2) Drop and drag method
3) Wipe method
4) Bath method
5) Soap solution method
6) Ultrasonic cleaning method

Solvents

Historically, germanium lenses components such as mirrors and beamsplitters have been cleaned by hand, using lint-free germanium lenses wipes and reagent-grade acetone or another liquid solvent such as methanol, ethanol, 97 percent pure isopropyl alcohol, methyl ethyl ketone (MEK) or methylene chloride (MEC). Some inorganic acids such as trichloroethylene (TCE), hydrofluoric acid (HF) and hydrochloric acid (HCl) may be used on uncoated silicon wafers, and nitric acid may be used on germanium substrates. Acidic solutions, however, should never be used on coated or uncoated zinc sulphide (ZnS) or zinc selenide (ZnSe) components.

Acetone is very good at dissolving grease, but it dries very quickly and always should be handled with acetone-impenetrable gloves. In general, isopropyl alcohol is a safe and effective cleaner – except for cleaning aluminium coatings. Because alcohol reacts with aluminium, it should never be used on protected or bare aluminium-coated mirrors. Methanol and most acidic solutions can be toxic or damaging to optics or coatings if misused, so care should be taken to follow the instructions provided by the manufacturer.

Liquid CO2 is a new technique that is used to remove oils and microscopic particles from germanium lenses waveguides, electro-germanium lenses devices, silicon wafers and a variety of biomedical, aerospace and semiconductor components. This process delivers a precisely controlled and purified spray alternated with warm air cycles to the germanium lenses surface. Because CO2 is noncorrosive and relatively nontoxic, it is safer to use than many traditional solvents, but it requires nontraditional procedures and a controlled, moisture-free work environment and so may incur additional expenses. In the long term, however, it may turn out to be a less expensive and a more effective means of achieving ultraclean surfaces, possibly resulting in coatings with higher damage thresholds.

Storage conditions

Once you have cleaned the optic, place it in the mount it will be used in or wrap it in lens tissue and place it in its container right away. The proper container to use is a polycarbonate/PTFE/PET-G box, in a cleanroom environment. The room temperature should be kept between 15 and 25 °C (60 to 80 °F). Ideally, humidity should be controlled and kept below 30 percent.

CAUTION: Do not use a polypropylene box. Studies have shown that permanent outgassing of the storage box leads to adsorption of products detrimental to laser resistance of coated optics.

This article comes from photonics edit released