Effects of packaging SrI2(Eu) scintillator crystals

Recent renewed emphasis placed on gamma-ray detectors for national security purposes has motivated researchers to identify and develop new scintillator materials capable of high energy resolution and growable to large sizes.

We have discovered that SrI2(Eu) scintillators has many desirable properties for gamma-ray detection and spectroscopy, including high light yield of ∼90,000 photons/MeV and excellent light yield proportionality. We have measured <2.7% FWHM at 662 keV with small detectors (<1 cm3) in direct contact with a photomultiplier tube, and ∼3% resolution at 662 keV is obtained for 1 in.3 crystals. Due to the hygroscopic nature of SrI2(Eu) scintillators, similar to NaI(Tl), proper packaging is required for field use.

This work describes a systematic study performed to determine the key factors in the packaging process to optimize performance. These factors include proper polishing of the surface, the geometry of the crystal, reflector materials and windows. A technique based on use of a collimated 137Cs source was developed to examine light collection uniformity.

Employing this technique, we found that when the crystal is packaged properly, the variation in the pulse height at 662 keV from events near the bottom of the crystal compared to those near the top of the crystal could be reduced to <1%. This paper describes the design and engineering of our detector package in order to improve energy resolution of 1 in.3-scale SrI2(Eu) scintillators crystals.

This article comes from sciencedirect edit released

Medical Filter – IPL Filter

IPL filter is the key optical element for IPL (intense Pulsed Light) machine, which filters the UV wave and reserve the useful wave from 400nm to 1200nm for cosmetic laser, such as photrevujenation, hair removal, vascular and acne treatment. The available wavelength are 550, 560, 570, 590, 615, 645, 695, 755,780 nm.

  • Material:N-BK7 Grade A optical glass, Fused silica, Sapphire crystal.
  • Dimension Tolerance:+/-0.1(General), +/-0.01(High Precision)
  • Thickness Tolerance:+/-0.2 (General), +/-0.005(High Precision)
  • Surface Quality:60/40
  • Clear Aperture:>90%
  • Parallelism<3 arc min. (General) , <5 arc sec.(High Precision)
  • Wavefront Distortion(per 25mm@633nm): λ/2 (General) , λ / 8(High Precision)
  • Bevel(face width x45°):0.2~0.5mm

Available wavelength: 515 ~ 1200, 530 ~ 1200, 550 ~ 1200, 560~ 1200, 570 ~ 1200, 590 ~ 1200,
615 ~ 1200, 645 ~ 1200, 695 ~ 1200, 755 ~ 1200, 780 ~ 1200 nm

Laser Line Bandpass Filter

Laser Line bandpass Filters transmit a well-defined center wavelength of light, with band pass width, while blocking the other unwanted radiation. Central Wavelength from 350 nm to 1550 nm, 350nm, 488nm, 515nm, 560nm, 590nm, 640nm, 755nm, 850nm, 980nm, 1060nm, 1310nm, 1550nm laser line type.
1nm, 3nm, 10nm, 12nm, 25nm, 40nm, and 70 nm Bandpass width etc.

This article comes from wavelength-tech edit released

Common Laser Crystals Dopants

Laser crystals are typically single crystals (monocrystalline material) which are used as gain media for solid-state lasers. In most cases, they are doped with either trivalent rare earth ions or transition metal ions. These ions enable the crystal to amplify light at the laser wavelength via stimulated emission, when energy is supplied to the crystal via absorption of pump light (→ optical pumping).

Compared with doped glasses, crystals usually have higher transition cross sections, a smaller absorption and emission bandwidth, a higher thermal conductivity, and possibly birefringence. (The article on laser crystals versus glasses discusses the differences in more detail.) In some cases, monocrystalline laser materials may be replaced with ceramic gain media, which have a fine polycrystalline structure.

This article comes from rp-photonics edit released

Well-type NaI(Tl) detector efficiency using analytical technique


• A new analytical approach for calculation of the full-energy peak efficiency is deduced.
• The method depends on the calculation of the photon path length.
• Separate calculation of factors which related to photon attenuation is introduced.
• The effective solid angle between source-to-detector is calculated.
• Remarkable agreement between measured and calculated efficiencies was achieved.

Well-type detectors play an important role in qualitative and quantitative analysis of low-activity samples, thanks to their pronouncedly high efficiency; this is particularly the case with scintillation detectors. In this work a theoretical approach to calculations of full-energy peak efficiencies of well-type detectors is elaborated.

The approach is based on the concept of the effective solid angle and the efficiency transfer principle. In parallel, ANGLE 4 software was employed to the same aim, using point sources positioned on 2″ × 2″ NaI(Tl) detector axis outside the detector well cavity. The theoretically obtained and ANGLE 4 calculated efficiency values were compared to the measured ones. These comparisons supported/confirmed both the theoretical concept and ANGLE 4 Software validity in well-type scintillation detectors calibration.

This article comes from science-direct edit released

Lasers used to form crystals

Our customers are of course laser experts but, when additional technical or applications support is required, we can call on many years of experience to assist them.

Our range of crystals for lasers is complemented by our range of high power laser diodes, electro-optic and non-linear crystals. More details can be found on our home page.

For medical solid state lasers we provide a full range of sizes, shapes, and quantities of ruby crystals for lasers, Er:YAG and CTH:YAG to meet the precise specifications of the medical laser manufacturer. Ruby lasers are used for cosmetic dermatology to remove unwanted hair, tattoos, portwine stains and similar skin blemishes. The advantage ruby laser treatment holds over other procedures is the 694 nm output does not affect normal, healthy skin in or around the treated area.

The series of medical YAG compositions generate output at discrete wavelengths between 2.1 and 3.0 microns. This spectrum couples well into water and body fluids. By selection among the different compositions in the medical YAG materials series, laser systems can be optimized for soft or hard tissue applications.

For industrial & high power solid state lasers we offer a full range of Nd:YAG crystals for lasers. Systems designers may select from several levels of dopant concentrations and rod configurations to optimize the performance of each laser system. Our range of dopants extends from 0.3%Nd through 1.4%Nd.

For lower power solid state lasers we have Nd:YVO4 available. This material has been growing in popularity because of its high gain low lasing threshold and high absorption coefficient at pumping wavelengths, resulting from th excellent fit of the neodymium dopant in the crystal lattice. We offer dopant concentrations from 0.1% upwards and a choice of coatings are available. As an alternative, Nd:GdVO4 can be used, the material benefitting from a much higher thermal conductivity and improved improved absorption.

For tunable lasers, titanium doped sapphire is an optically pumped, solid state laser material with an indefinitely long stability and useful life. It is the most widely used crystal for wavelength tunable lasers. Ti:sapphire crystals for lasers combine the robust properties of sapphire with the broadest tunable range of any known laser material. Laser output can be generated over the entire spectrum from 650 to 1100 nm. Frequency doubling the output provides tunability across the blue-green region of the visible spectrum.

For femtosecond and research lasers, titanium doped sapphire is a versatile crystal. Short, femto-second pulses can be produced successfully across the tunable range making Ti:sapphire ideal for ultra-fast spectroscopy. Other uses include nuclear fusion studies, micro-machining and very high speed read/write memory applications.

This article comes from roditi edit released

What Does a Ultraviolet Filter Do?

Put simply, UV filters reduce haziness created by ultraviolet lights.

Lets have a quick physics lesson. Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than x-rays, in the range 10 nm to 400 nm. If you own a film camera then you might know the reason you use a UV filter.

It all down to colour film having 3 sensitive layers, one to red, one to blue and one to green (RBG). The blue layer responses to UV light as well as blue light, if you take an image which lots of UV light the blue layer becomes overexposed and your image takes a blue colour.

You can buy different strength UV filters, stronger UV filters will stop more blue light and will leave the image with a slight yellow tone.

This article comes from photography edit released

Laser Crystals

Laser Crystals are the active gain medium in solid state laser systems. Laser crystals are used to generate the output of a laser through a variety of optical pumping techniques. The laser crystal’s composition determines its optical properties in addition to the application or laser type that the crystal is most suited for. Edmund Optics offers a wide variety of laser crystals for integration into a range of applications, including Nd:YAG, Nd:YVO4, Yb:KGW, Yb:KYW, and Ti:Sapphire.

Nd:YAG laser crystals feature high optical homogeneity, high damage thresholds, and have been AR coated for maximum throughput at 1064nm. Nd:YVO4 Laser Crystals feature a large stimulated emission cross section, high absorption of the pump laser source, and have been AR coated for maximum throughput at 808nm and 1064nm. Yb:KGW Laser Crystals are ideally suited as ultrashort pulse amplifiers or for use in in high power thin disk lasers, and have been AR coated for maximum throughput at 980 – 1064nm. Yb:KYW Laser Crystals are ideal for tuning of laser radiation in the range of 1020 – 1060nm and the generation of pulses shorter than 70fs and are AR coated for maximum throughput at 980 – 1064nm. Ti:Sapphire Crystals feature large emission bandwidths and excellent thermal conductivity and are used to generate ultrafast pulse lasers and high repetition rate oscillators.

This article comes from edmundoptics edit released

Background model for a NaI (Tl) detector devoted to dark matter searches

NaI (Tl) Detectors is a well known high light yield scintillator. Very large crystals can be grown to be used in a wide range of applications. In particular, such large crystals are very good-performing detectors in the search for dark matter, where they have been used for a long time and reported first evidence of the presence of an annual modulation in the detection rate, compatible with that expected for a dark matter signal. In the frame of the ANAIS (Annual modulation with NaI Scintillators) dark matter search project, a large and long effort has been carried out in order to characterize the background of sodium iodide crystals.

Here we present in detail our background model for a 9.6 kg NaI (Tl) detector taking data at the Canfranc Underground Laboratory (LSC): most of the contaminations contributing to the background have been precisely identified and quantified by different complementary techniques such as HPGe spectrometry, discrimination of alpha particles vs. beta/gamma background by Pulse Shape Analysis (PSA) and coincidence techniques; then, Monte Carlo (MC) simulations using Geant4 package have been carried out for the different contributions.

Only a few assumptions are required in order to explain most of the measured background at high energy, supporting the goodness of the proposed model for the present ANAIS prototype whose background is dominated by 40K bulk contamination. At low energy, some non-explained background components are still present and additional work is required to improve background understanding, but some plausible background sources contributing in this range have been studied in this work. Prospects of achievable backgrounds, at low and high energy, for the ANAIS-upgraded detectors, relying on the proposed background model conveniently scaled, are also presented.

This article comes from sciencedirect edit released

Athermal lenses for thermography elements

Thermal cameras cannot use regular glass lenses, as glass will reflect thermal radiation rather than allowing the radiation to pass through the lenses. Commonly used materials for athermal lenses for thermography are Germanium (Ge), Chalcogenide glass, Zinc Selenide (ZnSe) and Zinc Sulfide (ZnS).

These materials provide good transmission for wavelengths in the range of 8-15um, i.e. LWIR (Long-wavelength infrared). Sometimes LWIR is also called far infrared.

The athermal lenses standard

Athermal lenses for thermography do not use C- or CS-mount lenses which are commonly used on standard cameras. Instead they use other types of mounts. The first documented thermal lens standard is TA-LENS. The letters “TA” stand for Thermal A, where “A” stands for the first documented standard.

Athermallenses provide a male thread which connects with a female thread on the camera. The thread is nominally 34 mm in diameter, with a pitch of two threads per mm (M34x0.5mm).

The athermal standard and an example of a athermal lens design

The lens mount is large enough for sensors with a diameter up to at least 13mm, which means that it works for commonly used LWIR sensors.

As the thread size is relatively large, it is possible to make adapters for other, smaller lenses for example lenses using M24x1 threads or M25x0.5mm threads.

Sample test chart images captured by an LWIR camera using (left) a 60 mm lens and (right) using a 10 mm. Both images are captured by a camera using the athermal lenses standard.

Long pass IPL glass filters

Long pass IPL glass filters are useful for selective wavelength absorption and therefore achieve high out of band blocking. Colour glass type Longpass filters have very low transmission in short wavelengths and high transmission in the long wavelengths. These filters are used in range of spectral selection scientific instrument applications.

The long-pass range of IPL glass filters listed here has uniform spectral transmission properties over their entire aperture. A wide range of Long pass IPL glass filters are available as 50x50mm and 25mm diameter filters, stocked in the options below.

Stock Long pass IPL glass filters are available to purchase directly from this website. To enquire about our customer colour glass capabilities, or to place a custom order, please contact our technical sales team.

This article comes from knightoptical edit released