There is some attenuation of this NIR radiation while passing through the atmosphere however, there is still enough NIR radiation available for recording natural scenes. Within its spectrum there is ample NIR radiation available between wavelengths of 800 nm and 1100 nm, 5 which may be used in daylight NIR photography. Scheme of how incoming radiation is modified before being detected: 1) path from Sun to object 2) object absorption and/or scattering 3) path from object to observer 4) detection.įor atmospheric optics, the natural light sources are the Sun or Moon. 4, 6- 8 In this work, we refer to NIR as the wavelength range from 780 nm to 1100 nm, which can be nicely covered by Si-based sensors. 5 Other characteristics of NIR photography have been discussed recently. ![]() 4 Here we present observations of atmospheric optical phenomena with such a modified camera operating in the NIR region above 800 nm wavelengths. To illustrate this approach, we used a modified digital single-lens reflex (DSLR) camera with the IR-blocking filter removed from the front of the detector, making the camera operate in the NIR. Presenting example images and discussing the differences between the VIS and near infrared (NIR) features provides a different and attractive approach to teach the relevant physical processes responsible for producing the phenomena. Using detectors in adjacent regions to the visible (VIS) range will result in images that may differ appreciably from the visual appearance owing to the different detector spectral response and the wavelength-dependent light scattering processes in the atmosphere. ![]() From a physics point of view, using a camera to record images rather than the eye for observing the phenomena just means that the detector signal, based on its spectral response, is changed. ![]() 1- 3 These naked eye observable features are particularly suitable for teaching optics. Rainbows, halos, coronas, glories, and mirages are well known beautiful natural phenomena.
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