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An opaque substance transmits no light, and therefore reflects, scatters, or absorbs all of it. Other categories of visual appearance, related to the perception of regular or diffuse reflection and transmission of light, have been organized under the concept of cesia in an order system with three variables, including opacity, transparency and ...
The opaque projector, or episcope is a device which displays opaque materials by shining a bright lamp onto the object from above. The episcope must be distinguished from the diascope , which is a projector used for projecting images of transparent objects (such as films), and from the epidiascope , which is capable of projecting images of both ...
When infrared light of these frequencies strikes an object, the energy is reflected or transmitted. If the object is transparent, then the light waves are passed on to neighboring atoms through the bulk of the material and re-emitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. [10] [11]
For example, NASA's Navigation and Ancillary Information Facility defines that a body in the umbra is also within the penumbra. [2] Scale diagram of Earth's shadow, showing how the umbral cone extends beyond the orbit of the Moon (The Moon is indicated by the yellow dot.) Earth's umbra, as seen during a partial lunar eclipse
The opaque projector, or episcope is a device which displays opaque materials by shining a bright lamp onto the object from above. The episcope must be distinguished from the diascope , which is a projector used for projecting images of transparent objects (such as films or slides), and from the epidiascope , which is capable of projecting ...
Due to the magnitude of c, the effect of light pressure is negligible for everyday objects. For example, a one-milliwatt laser pointer exerts a force of about 3.3 piconewtons on the object being illuminated; thus, one could lift a U.S. penny with laser pointers, but doing so would require about 30 billion 1-mW laser pointers. [22]
This allows illuminating an opaque object from the side of the objective, with the light source positioned behind the specimen as in a transmission microscope. The device is named after Johann Nathanael Lieberkühn (1711–1756) who used and popularized it but did not invent it. Similar mirrors were described and used by earlier microscopists ...
Around 1872 Henry Morton used an opaque projector in demonstrations for huge audiences, for example in the Philadelphia Opera House which could seat 3500 people. His machine did not use a condenser or reflector, but used an oxyhydrogen lamp close to the object in order to project huge clear images. [37]