Can we see the laser pointer in space?
Your Laser pointer, want to know how far the light will go before it stops? In fact, at some point, some of you asked yourself an obvious question when aiming it at a high place-can you see the laser pointer from the sky? As early as 1962, both the United States and the Soviet Union began to use lasers to measure the distance between the earth and the moon. On July 21, 1969, the US Apollo 11 put the first laser reflector array on the moon at a designated location. Relying on this 46 cm square reflector, we finally carried out an accurate measurement of the distance between the earth and the moon. The laser pointer does not emit enough photons, so no photons can penetrate the atmosphere to reach the moon.
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The McDonald Observatory in Texas originally used a 3 Joule ruby laser. The laser beam emitted was roughly the same wavelength as the commercial red laser pointer, but the power was 600 times the power allowed by the commercial laser pointer. In order to make the beam as close as possible, the laser is emitted with the optics of a 1/7m telescope. However, the atmosphere will cause the laser beam to be distorted, diverging before reaching the moon, and it is estimated that the diameter has become 10 kilometers. Only precision instruments can detect the few photons reflected by the telescope and returning through the atmosphere, several million kilometers away from the retroreflector of the moon.
2021-10-08 09:00:51
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