Photonics/​Optics

The dark current of a transferred-electron photocathode with an InGaAs absorber, responsive over the 0.9-to-1.7-μm range, must be reduced to an ultralow level suitable for low signal spectral astrophysical measurements by lowering the temperature of the sensor incorporating the...

Digitally enhanced heterodyne interferometry (DI) is a laser metrology technique employing pseudo-random noise (PRN) codes phase-modulated onto an optical carrier. Combined with heterodyne interferometry, the PRN code is used to select individual signals, returning the inherent interferometric sensitivity...

Theodolites are a common instrument in the testing, alignment, and building of various systems ranging from a single optical component to an entire instrument. They provide a precise way to measure horizontal and vertical angles. They can be used to align multiple objects in a desired way...

NASA's Hubble Space Telescope has found what astronomers believe to be the most distant object ever seen in the universe, 13.2 billion light years away. This places the object roughly 150 million light years more distant than the previous record holder. The dim object is a compact galaxy made of blue stars that...