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What materials are suitable for infrared lenses?

When designing infrared optical components, various factors related to the optical materials used must be considered. These factors include refractive properties, optical transmission, non-thermal properties, hardness/durability, environmental sensitivity, weight/density, manufacturing technology, and cost. Some of these factors are still interrelated. For example, for some materials, their optical transmittance is high at room temperature, but decreases at higher temperatures. Considering all these factors, when designing infrared optical components, careful consideration of material selection is required. Available materials are: germanium (Ge), silicon (Si), gallium arsenide (GaAs) and cadmium telluride (CdTe); zinc compounds, such as zinc sulfide (ZnS) and zinc selenide (ZnSe); water-soluble crystals, such as Potassium bromide (KBr), sodium chloride (NaCl) and potassium chloride (KCl); fluorides such as magnesium fluoride (MgF2), calcium fluoride (CaF2) and barium fluoride (BaF2); and other materials, Such as fused silica and sapphire; chalcogenide glass, etc. The currently available materials are as follows (blue is chalcogenide glass):

What is an AR coating

Anti-reflective coating (English: Anti-reflective coating, AR) is a surface optical coating that increases transmittance by reducing light reflection. In complex optical systems, it can improve contrast by reducing scattered light in the system. Many coatings include transparent film structures with different refractive indices. The thickness of the film determines the wavelength of the reflected light that it acts on. When light is reflected twice on the AR coating, it will interfere with the original reflected light, thereby weakening the reflected light. According to the conservation of energy, the energy of light does not change. Therefore, when the reflected light decreases, the transmitted light increases. This is the principle of AR coating. Generally, when choosing an AR coating, you need to determine the wavelength, such as infrared, visible and ultraviolet.

What is an atmospheric window?

Atmospheric window fefers to some bands of celestial radiation that can penetrate the atmosphere. Due to the absorption and reflection of radiation by various particles in the earth's atmosphere, only radiation from celestial bodies in certain wavebands can reach the ground. Divided into optical window, infrared window and radio window according to their respective scopes.Infrared window Water vapor molecules are the main absorbers of infrared radiation. Strong water vapor absorption bands are located at 0.71~0.735μ (micron), 0.81~0.84μ, 0.89~0.99μ, 1.07~1.20μ, 1.3~1.5μ, 1.7~2.0μ, 2.4~3.3μ, 4.8~8.0μ. An absorption band of carbon dioxide appears at 13.5~17μ. The gaps between these absorption bands form some infrared windows. The widest infrared window is at 8-13μ (there is an absorption band of ozone near 9.5μ). 17~22μ are translucent windows. After 22μ until the wavelength of 1 millimeter, due to the severe absorption of water vapor, it is completely opaque to observers on the ground. But in places with high altitude and dry air, the radiation transmittance of 24.5~42μ can reach 30~60%. At 3.5 kilometers above sea level, radiation of 330-380μ, 420-490μ, 580-670μ (transmittance of about 30%) can be observed, and 670-780μ (about 70%) and 800-910μ (about 30%) can be observed. 85%) radiation.

How does the MTF curve reflect the performance of the lens?

1. The space enclosed by the MTF curve, the horizontal axis and the vertical axis, the larger the area, the better, and the better the lens imaging performance. The flatter the MTF curve, the better. The flatness indicates the imaging uniformity of the edge and center of the lens.2. The closer the sagittal curve and the meridian curve, the better, and the more consistent the imaging in different directions. 3. The low frequency curve represents the contrast characteristics of the lens, and the high frequency curve represents the resolution characteristics of the lens.

How can the thermal imaging module without zooming and automatic focus function realize the automati

Although without zooming and automatic focus function, even installed with a continuous zoom lens or motorized lens, the thermal imaging module can't realize zooming or automatic focus function, We can realize these functions in the case of not changing thermal imaging module by using other subsidiary products like automatic focus control board.The Principle of operation is easy. Connect the motor and potentiometer to the control board, by which sending the command to control the motor. Then the analog video of the thermal imaging module is output to the control board which will analyze the analog video. In the process of the automatic focus, the control board will analyze the position of the focus motor corresponding to the clearest picture, and then control the focus motor running to the position through the control board to complete the automatic focus. As soon as the customer have their needs, we will try our best to meet the need. The Y02 control panel provided by our company have lots of functions:Besides the basic zooming and automatic focus function, it has the present position function, the designated location zooming and focus function, the automatic focus fine tuning function, the automatic reading zooming and focus functions of the upper and lower limits. In order to ensure that our control panel can meet the requirement of the most customer and be suitable for most application scenarios, the temperature compensation function, the encoder motor control function and focal automatic control function are currently being added. Contact us directly if details about the Y02 control board are required.

What are the categories of analog video?

There are three main formats of analog video signals; PAL,NTSC and SECAM, in which PAL is called P system and NTSC is called N system, as is often said.PAL (phase Alternating Line) is a TV system established in 1965. With the exception of NTSC in parts of North America and East Asia and SECAM is adopted in most parts of the world, which serves 25 frames per second.NTSC is the color television broadcasting standards formulated by National television setting committee in 1952. It is adopted by most of the American countries, like America, Canada and Mexico, and China Taiwan, Japan, Korea and Philippine, as well as some TV company in Hongkong, South China. It serves 30 frames per second.ECAM: At present, countries that adopted SECAM is mainly commonwealth of In dependent stares, such as Russia,France, Egypt and some French-speaking countries in Africa. Therefore, in order to ensure that the analog video output of the movement can be used normally, modules will output two kinds of analog video: PAL and NTSC for choice.

How does the spectral filter work?

There are two general types of spectral filters for thermal imaging cameras.   One is a neutral density filter (ordinary filter), which attenuates the energy of the entire wavelength range to the same degree. For example, neutral density filters can calibrate thermal imaging cameras to higher temperatures and radiation ranges, such as 3000°C.   Another type of filter is a spectral filter, which shields the radiant energy in a specific band, which is helpful for you to test in the band of interest—for example, shooting and tracking a chemical gas plume visible only in a narrow area of the spectrum or depicting a target through the target flame. Under normal circumstances, the heat generated by the flame will occupy the main part of the image, but the spectral filter can shield it, allowing you to see what you want to see.

What is a reflex peripheral infrared thermal imaging optical system, and what are its advantages

Title The peripheral vision imaging system can stare and image the space within the range of 360° azimuth angle and certain pitch angle. This panoramic thermal imaging solution avoids using multiple thermal imaging cameras placed in different viewing directions to achieve panoramic imaging or rotating a single thermal imaging camera to achieve panoramic imaging (which will cause image delay). Still, this solution also has certain limitations. This solution must use a large-scale area array focal plane device to improve the thermal imaging system's resolution. This kind of scheme is mainly used for a limited range, which is only suitable for short-distance security monitoring and warning and is unsuitable for long-distance detection and imaging.

What are the characteristics of SWIR shortwave infrared?

l  Higher resolution   l  Strong fog penetration ability   l  Low-light imaging (night vision capability) The glow of the atmosphere at night contains shortwave infrared components. Shortwave infrared can be imaged in the lowest starlight night, with a particular night vision capability.   l  Identify the target Shortwave infrared is very sensitive to moisture. Objects lacking moisture appear white, and objects rich in moisture appear black, help to identify inanimate objects.   l  Detection of concealed lighting Illumination with a wavelength of 1550nm, which is safe for the human eye, is invisible to the naked eye but can be easily seen by a shortwave infrared camera.

Does the atmosphere have a significant influence on infrared thermal imaging?

The target radiation can only reach through the air and be imaged on the infrared thermal imaging camera. In addition to attenuating the target's radiation, the air will also add some interference signals during the transmission process. In the infrared band, the atmosphere is transparent at some wavelengths and opaque or semi-transparent at other wavelengths. Therefore, the infrared radiation measured by a target at a close distance is different from the radiation emitted from the same target at a long distance.

What is the error tolerance of temperature compensation?

The actual optical system cannot achieve strict temperature compensation, that is, in a certain temperature range, the image surface of the system cannot be consistent with the change of the lens barrel with complex structure, which requires an Error tolerance for temperature compensation.   In a broad sense, the image defocuses caused by temperature can be regarded as a kind of aberration. According to the Rayleigh law of optical system aberration, the temperature compensation error should be controlled at its maximum wave aberration less than 1/4 wavelength.

What are the types of mechanical compensation in the athermal design of an infrared lens?

1)  Mechanical (electromechanical) active temperature compensation   From the basic theory of optics, we know that when the axial position of a lens (or lens group) in the optical system is changed, the focal plane position of the system will change accordingly. Active temperature compensation uses this principle to reproduce the system. The focus and adjustment method can be manual or electric. Motorized IR lens and manual IR lens can be understood as a kind of active mechanical/manual compensation athermal lens.   To improve the sensitivity of adjustment and maintain the stability of the optical axis, this temperature compensation method generally requires a precise mechanical transmission mechanism. At the same time, the required stroke of the temperature compensation lens should be investigated, and the most sensitive lens affected by the focusing surface should be selected as the temperature compensation element.   The basic mechanical transmission structure of this compensation method is basically the same as the focusing mechanism of the optical system. The method is simple in principle and easy to implement, but it increases the weight of the optical instrument, and at the same time easily brings about aiming errors.   2)  Mechanical (electromechanical) passive temperature compensation   The principle of mechanical (electromechanical) passive temperature compensation is basically the same as that of active temperature compensation, except that the way of changing the lens group has changed. It uses certain materials or mechanisms with special functions to realize automatic adjustment. 

What should be attentive to in the athermalization design of infrared thermal imaging lens?

In the process of athermal design of the infrared optical system, the following issues should be paid attention to. (1) With the change of temperature, the original aberration compensation relationship is destroyed, and the best focus position of the system may change nonlinearly with the change of temperature.   (2) For the reflection system, if the material of the mirror is the same as the material of the lens barrel (or the material has the same thermal expansion coefficient), when the temperature changes, the system will only zoom in or out to a certain extent, and the temperature will affect the performance of the system Not big, in principle, no heat dissipation design is required.   (3) Since the mechanical lens barrel for installing the lens is complex in most cases, the way of expansion (or contraction) of the lens barrel with different structures is not necessarily the same when the temperature changes. Based on the heating equation, specific analysis is made according to the specific problems of different lens barrel structures to ensure a good heat dissipation effect.

What is the purpose of infrared optical athermalization for infrared lenses?

Infrared optical systems often work in environments with a relatively large temperature range. The thermal expansion coefficient of optical materials and mechanical materials and the change in refractive index of optical materials with temperature will seriously affect the performance of the optical system.   Compared with optical materials in the visible light band, the refractive index of most infrared optical materials changes with temperature gradient dn/dt relatively large, so the thermal effect of the infrared optical system is more obvious.   To obtain satisfactory image quality, we can use mechanical (electromechanical) methods or optical methods to achieve the athermalization of the system. For instance, use a manual or closed-loop servo system to adjust the distance between optical parts to realize the refocusing of the system under the new temperature environment. Or by selecting appropriate optical materials and rationally distributing the optical power of each optical component to achieve optical athermalization.   When ambient temperature change affects the performance of the entire infrared system, an athermal design is required. In this regard, the Quanhom team has accumulated a wealth of experience. If you require a thermal lens, the Quanhom team will be professional Knowledge and an enthusiastic attitude to serve you.