Due to the extreme dependence of our thermal emission characteristics on the wavelength of the heat source, only certain wavelength ranges are suitable for measurements of thermal. The following figures reveal the range of thermal transmission of common thermal lenses and window substances for infrared thermometers. The blue-colored curve demonstrates the general rule applicable to all materials, and represents the average value over a temperature interval of zero (black) to infinity (green) that is the cold-pressure limit (CPL).
For lenses and windows the cold-pressure limit is defined as the maximum measured value of the damping ratio of a material in relation to the thermal gradient. This ratio is calculated as a function of the temperature variation along a viewing angle for a given viewing angle and cte of a lens or window. The bending moment of a system is the change in the angle of incidence, which is linear or spherical. This causes the slope to be proportional to this curve. The focal length of a system is also a factor in the slope. This can be thought of as a function of the focal length divided by the period of the curve (i.e. the time between shots).
The temperature of the inside of the system will always be within the prescribed curve for the given temperature and the focal length of a window assembly or lens. This is also referred to as a “curved top”. For instance, the curve for the thermal conductance of a glass bead inside a glass vial with holes in it could be plotted as a function of the focal length and the temperature difference within the vial between the bottom of the bead and the surface of the vial, and the angle of incidence for a particular window assembly. If the aperture is fixed for all shots, then the area between the system’s surface temperature and the curve of variation will remain the same. If the aperture is variable, then the curve may be curved because of the fluctuation in the temperature of the glass used to create the bead, the temperature of the ambient atmospheric air on the inside of the vial’s surface, and the focal length as well as the duration of shooting. A signature left by photographer on the petals of a flower is an example of a curly surface.
A window and lens should be mounted in a manner that their focal points and lines of sight are correctly aligned. If the temperature of the inside of the system is too cold for the lens, then the outside surface temperature of the frame will be lower and the inside temperature of the lens will be too warm. If the temperature outside of the lens and the frame are the same and the frame is at the same temperature, it will not require any adjustments to counteract the heating or cooling effects of internal temperature variations. The inside temperature of the frame will be in line for a specific focal length without the need for any other adjustments, provided no external source of temperature fluctuations affects the system. If the system is located in an area that has restricted or blocked views of surrounding buildings or scenery, it may be necessary to regulate the internal temperature.
The first mechanical interlocking system that was used to mount lenses to camera were made of plastic. This design was later adopted for use with pinhole glasses. The issue with this kind of lens assembly is that the mechanical joints between the frame and the lens could indent or even break. In the event of this occurring, it would be necessary for the entire assembly to be replaced within an extremely short amount of time. This is the reason this system has been replaced with more durable designs.
Pinhole glasses lenses are generally constructed with a frame made of metal and a thin, plastic or glass lid. The lense designs should at the very minimum have a hermetically-sealed construction. A hermetically sealed lens construction has a sealed surface at the bottom and top. The top layer could have a similar mechanical seal as the one mentioned earlier. It could also be a source of adhesive, lip, or layer of plastic film.
Another embodiment of this type of lens and window assembly is a lens surface that contains a substrate, which adheres to the base of the window assembly. This type of system usually consists of a window casing as well as a series of compartments for lenses. The windows can also house other kinds of devices, like light emitters, or thermometers. This kind of system may also include the thermostat or light emitter that regulates the temperature in the room. A variety of compartments could be used to house the temperature controller as well as a variety of other devices, such as an alarm clock, thermostat, or other devices.
This isn’t a complete list of all kinds of window assemblies and lenses that are available. However, it is indicative of the most important technologies associated with this invention. For more information, read the complete disclosure. Please refer to the sections that pertain to “details about the present invention” and “Description of the process with Regard to the Identification of the various types of products That Are Involved In the Present Application.”
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