IR Lenses for Cooled Detectors

IR Lenses for MWIR Cooled Thermal Imaging Cameras
● Aspherical and binary optical technology adoped in design
● Various types of IR materials are used

Hangzhou Shalom Electro‐optics Technology Co., Ltd.

The lenses are designed and used in middle wavelength infrared range (MWIR) thermal imaging cameras of cooled FPA detectors at 3-5μm, with manual or motorized mechanism and in wide range of  focal length, the single FOV and double FOV lenses modules are available. The designed modules are
listed for your selection, and the customs modules are available for customer’s  request.

Modules or Types
The modules are designed for 320 x 256 – 30um/640 x 512 – 15um MWIR cooled detector at  3-5μm.

Features
1.  Aspheric Technology and Binary Optics Technology are used in design, which effectively reduce  the spherical aberration, distortion and other various aberrations, achieve athermalization design and  reduce the number of needed lens elements, lower the cost.

2. Various type of the infrared materials (like Ge, ZnSe, ZnS, AMTIR, CaF2, Sapphire, BaF2 ect.) are used in the lenses, which would successfully eliminate the aberration of the image and improve the quality of imaging, especially for the large diameter telephoto lenses.

3. Advanced equipment and machines are used to process the infrared materials optics: ultra-precision single point diamond processing machine to achieve the precision aspheric in 3nm, diffractive surface processing equipment to process the Ge, ZnSe, ZnS and AMTIR materials.

4. Different types of coating are made on the lens optics: high-efficiency anti-reflection coating (or high-efficiency AR), durable anti-reflection coating (or Durable AR) and diamond-like hard carbon coating(or DLC coating).

5. Complete quality assurance system
6. Within our quality system, we works out a series of specific craftworks and develops a strict test  procedure to guarrantee the quality of products.

Properties of scintillators

There are many desired properties of scintillators, such as high density, fast operation speed, low costradiation hardness, production capability and durability of operational parameters. High density reduces the material size of showers for high-energy γ-quanta and electrons. The range of Compton scattered photons for lower energy γ-rays is also decreased via high density materials. This results in high segmentation of the detector and leads to better spatial resolution. Usually high density materials have heavy ions in the lattice (e.g., leadcadmium), significantly increasing the photo-fraction (~Z4).[further explanation needed] The increased photo-fraction is important for some applications such as positron emission tomography. High stopping power for electromagnetic component of the ionizing radiation needs greater photo-fraction; this allows for a compact detector. High operating speed is needed for good resolution of spectra. Precision of time measurement with a scintillation detector is proportional to √τsc. Short decay times are important for the measurement of time intervals and for the operation in fast coincidence circuits. High density and fast response time can allow detection of rare events in particle physics. Particle energy deposited in the material of a scintillator is proportional to the scintillator’s response. Charged particles, γ-quanta and ions have different slopes when their response is measured. Thus, scintillators could be used to identify various types of γ-quanta and particles in fluxes of mixed radiation. Another consideration of scintillators is the cost of producing them. Most crystal scintillators require high-purity chemicals and sometimes rare-earth metals that are fairly expensive. Not only are the materials an expenditure, but many crystals require expensive furnaces and almost six months of growth and analyzing time. Currently, other scintillators are being researched for reduced production cost.

Several other properties are also desirable in a good detector scintillator: a low gamma output (i.e., a high efficiency for converting the energy of incident radiation into scintillation photons), transparency to its own scintillation light (for good light collection), efficient detection of the radiation being studied, a high stopping power, good linearity over a wide range of energy, a short rise time for fast timing applications (e.g., coincidence measurements), a short decay time to reduce detector dead-time and accommodate high event rates, emission in a spectral range matching the spectral sensitivity of existing PMTs (although wavelength shifters can sometimes be used), an index of refraction near that of glass (≈1.5) to allow optimum coupling to the PMT window. Ruggedness and good behavior under high temperature may be desirable where resistance to vibration and high temperature is necessary (e.g., oil exploration). The practical choice of a scintillator material is usually a compromise among those properties to best fit a given application.

Among the properties listed above, the light output is the most important, as it affects both the efficiency and the resolution of the detector (the efficiency is the ratio of detected particles to the total number of particles impinging upon the detector; the energy resolution is the ratio of the full width at half maximum of a given energy peak to the peak position, usually expressed in %). The light output is a strong function of the type of incident particle or photon and of its energy, which therefore strongly influences the type of scintillation material to be used for a particular application. The presence of quenching effects results in reduced light output (i.e., reduced scintillation efficiency). Quenching refers to all radiationless de‑excitation processes in which the excitation is degraded mainly to heat.[5] The overall signal production efficiency of the detector, however, also depends on the quantum efficiency of the PMT (typically ~30% at peak), and on the efficiency of light transmission and collection (which depends on the type of reflector material covering the scintillator and light guides, the length/shape of the light guides, any light absorption, etc.). The light output is often quantified as a number of scintillation photons produced per keV of deposited energy. Typical numbers are (when the incident particle is an electron): ≈40 photons/keV for NaI(Tl), ~10 photons/keV for plastic scintillators, and ~8 photons/keV for bismuth germanate (BGO).

Scintillation detectors are generally assumed to be linear. This assumption is based on two requirements: (1) that the light output of the scintillator is proportional to the energy of the incident radiation; (2) that the electrical pulse produced by the photomultiplier tube is proportional to the emitted scintillation light. The linearity assumption is usually a good rough approximation, although deviations can occur (especially pronounced for particles heavier than the proton at low energies).

Resistance and good behavior under high-temperature, high-vibration environments is especially important for applications such as oil exploration (wireline logging, measurement while drilling). For most scintillators, light output and scintillation decay time depends on the temperature. This dependence can largely be ignored for room-temperature applications since it is usually weak. The dependence on the temperature is also weaker for organic scintillators than it is for inorganic crystals, such as NaI-Tl or BGO. Strong dependence of decay time on the temperature in BGO scintillator is used for remote monitoring of temperature in vacuum environment. The coupled PMTs also exhibit temperature sensitivity, and can be damaged if submitted to mechanical shock. Hence, high temperature rugged PMTs should be used for high-temperature, high-vibration applications.

From Wikipedia, the free encyclopedia

Infared Spherical Lenses(Infared Spherical Lenses)

Hangzhou Shalom EO provides the spherical optical lenses used in thermal imaging cameras at wavelength range MWIR (3-5μm) and LWIR (8-12μm), the lenses are customized and made according to customer’s drawings and requirements. The plano-convex, plano-concave, double convex and meniscus lenses are available, the lens substrates are made from infrared materials: Ge, ZnSe, ZnS, CaF2, BaF2, GaAs, AMTIR glass, Si, Sapphire ect.

thermal imagings\optics for IR lenses\IR Spherical Lenses

 

Features

Optical Lenses works at MWIR (3-5μm) and LWIR (8-12μm) wavelength range;
Substrates materials: Ge, ZnSe, ZnS, CaF2, BaF2, GaAs, AMTIR glass, Si, Sapphire;
Various coating: high-efficiency AR, durable AR and DLC coating are available;
Specifications conformed to military standard.

Main elements of laser crystal

The activated ions used in the laser crystal(Hangzhou Shalom Laser Components) are mainly transition metal ions and trivalent rare earth ions. The optical electron of the transition metal ion is the 3d electron in the outer layer. In the crystal, the optical electron is directly affected by the surrounding crystal field, so the spectral characteristics of the crystal of different structure types are greatly different. The 4f electrons of the trivalent rare earth ions are shielded by the outer electrons of 5s and 5p, so that the effect of the crystal field is weakened, but the perturbation of the crystal field makes the 4f electron transition which is originally forbidden possible, resulting in narrow band absorption and fluorescence. Spectral line. Therefore, the spectrum of trivalent rare earth ions in different crystals is not as large as that of transition metal ions. The matrix crystals used in laser crystals are mainly oxides and fluorides. As a matrix crystal, in addition to its physicochemical properties, it is easy to grow large-size crystals with good optical uniformity, and it is cheap, but consider its compatibility with activated ions, such as the radius of the matrix cation and activated ions, and the electronegativity. Sex and valence should be as close as possible. In addition, the effect of the host crystal field on the activation ion spectrum is also considered. For some special-purpose matrix crystals, the addition of activated ions can directly produce lasers with certain characteristics. For example, in some nonlinear crystals, the activated ions generate laser light and can be directly converted into harmonic output through the matrix crystal. More used: Nd:YAG, Nd:YVO4

The origin and development of laser components

The origin and development of laser components

Hangzhou Shalom EO provides the crystals, optics and components used in the lasers, which includes: Laser crystalsnonlinear crystalsopticsPPLN crystalspockels cells and passive Q-switches, waveplates and polarizing optics. Beside the general lasers, optics and Components for femto-second lasers, CO2 lasers, deep UV lasers, ring laser gyro-scope are available. And the high precision optics for demanding applications are offered.

The light source required for fiber optic communication in laser devices should be a high-speed modulated light source to carry large-capacity information. Such as lasers and LEDs. The so-called “modulation” is to change the intensity of light, etc., according to the information to be transmitted, to carry information.

The light source required for fiber-optic communication should be a high-speed modulated light source to carry large-capacity information. Such as lasers and LEDs. The so-called “modulation” is to change the intensity of light, etc., according to the information to be transmitted, to carry information. In 1960, Maimen invented the ruby ​​laser. The difference between laser and ordinary light is that the laser has a very simple optical frequency and has a linear line. In optical, it is called coherent light, and it is most suitable for light source of optical fiber communication. The usual light frequency is very messy and it contains many wavelengths. The usual light frequency is very messy and it contains many wavelengths. The characteristic of coherent light is that the light energy is concentrated, and the divergence angle is small, which is approximately parallel light. After the invention of the ruby ​​laser, various lasers were born: gas lasers, such as helium neon lasers; solid-state lasers, such as YAG yttrium aluminum garnet lasers; chemical lasers; dye lasers. Among them, the semiconductor laser is most suitable for the light source of optical fiber communication. Its small size and high efficiency, its wavelength is suitable for the low loss window of the fiber. However, the manufacturing process of semiconductor lasers is very complicated, and it is necessary to epitaxially grow five layers of doped semiconductor on a substrate material of extremely high purity and defect, and then lithographically illuminate the micron-sized optical waveguide thereon, which has a difficulty compared with the optical fiber. Nothing more than that. In the late 1970s, a semiconductor laser with a long working life at room temperature was finally produced. In 1976, the world’s first practical fiber-optic communication line was established in Atlanta, USA. At this time, the semiconductor laser has not passed, and the light source is a semiconductor light-emitting tube. In the early 1980s, single-mode fibers and lasers were mature, and the superiority of fiber-optic communication capacity was gradually brought into play.
The light emitted by the semiconductor laser is pure, the energy is concentrated, and the beam is very thin. It can efficiently shoot into a single-mode fiber with a core diameter of only 8 microns. Today’s high-speed fiber-optic communication systems use semiconductor lasers as light sources.