Because of the dependence of our thermal emission characteristics on the wavelength of the thermal due to the dependence of our thermal emission behavior on the wavelength, only a few wavelengths are suitable for thermal measurements. The following diagrams illustrate the ranges of thermal transmission of common window and thermal lenses for infrared thermometers. The blue-colored curve is the general rule for all materials. It is the average value across the temperature range of zero (black) and infinity (green) and that is the cold-pressure limit (CPL).
For lenses and windows the cold-pressure limit is defined as the highest measured value of the damping ratio of a substance against the thermal gradient. This ratio is plotted as a function of the temperature differential along the viewing angle for a particular viewing angle and cte for the window or lens. The bending moment of a system is the change in angle of incidence from spherical or linear. This causes the slope to be proportional to the curve. The slope of this curve is also proportional to the focal length of the system, which can be thought of as an expression of the focal length divided by the length of the curve (i.e. the period between shots).
For a particular set of temperature and a given focal length of a lens or window assembly, the internal surface temperature of the system will always fall within the prescribed range in a perfect regularity known as a “curved surface.” The thermal conductance curve of a glass beads inside a glass vial could be plotted as a function the focal length as well as the temperature difference between the bottom of the vial and its surface and the angle of incidence of a given window. If the aperture is fixed for all shots, then the distance between the inside surface temperature of the system and the curve of variation for the particular window assembly should always remain constant. Variable apertures can cause the curve to become curvilinear because of variations in the glass’s temperature used to create the bead and ambient air temperature focal length, and time of photography. A good example of a curly surface can be seen in the signature of a photographer of flowers.
A lens and window must 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 cooler and the inside temperature of the lens will be too hot. When the outside temperature of the lens and the frame are equally and the frame is at the same temperature, it will not require any adjustments to compensate for the heating or cooling effects of internal temperature variations. If there aren’t any temperature differences from outside, then the system’s inside surface temperature will be the same for the given focal length. However, if the camera is mounted at a location with an obstruction or limited view of any surrounding building or scenery and the surrounding area, then internal temperatures might require to be controlled.
The first mechanical interlocking systems used to mount lenses to cameras were constructed of plastic or other materials that could bend or mold according to changes in mounting pressure. This innovation was later adapted for use with pinhole glasses. This type of lens assembly is not without a problem with the mechanical joints that connect the lens and frame might break or become indented. If this were to happen, occurring, it would be required for the entire assembly to be replaced within the shortest amount of time. This is the reason why this system is being replaced with more durable models.
Lenses designed for use with pinhole glasses usually have frames made of metal and an elongated glass or plastic lid. At the very least the lense designs should include a hermetically sealed lens construction. A hermetically sealed lens has a sealed surface on the bottom and at the top. The top surface may contain a mechanical seal similar to that previously mentioned. It could also include an lip, adhesive, or layer of plastic film.
A lens surface that is an adhesive and is bonded to the base is a different example of this type of window and lens assembly. This system usually consists of a glass casing and a series of lens compartments. Other kinds of devices can be used in the windows, for example, light emitters and thermometers. This kind of system may also include the thermostat or light emitter which controls the temperature of the room. In this scenario the system would comprise of compartments that could be used to house the temperature controller along with a number of other devices, like an alarm clock or thermostat.
This is not an exhaustive list of all kinds of window and lens assemblies. However, it is indicative of the important technologies that are associated with this invention. For more information, please look over the entire disclosure. Refer to the sections that pertain to “details regarding the present invention” and “Description of the process with Respect To the Identification of the various classes of products that are involved in the Present Application.”
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