Submitted via IRC for Fnord666
[...] When the beam exits the cube, the reflected light from the left portion of the beam and the transmitted light from the right portion of the beam are emitted from one face of the cube. Conversely, the transmitted light from left portion of the beam and reflected light from the right portion are emitted from another face of the cube.
This creates an extremely stable "Interference" pattern for Guo and his team to measure all the key spatial characteristics of a light beam- its amplitude, phase, polarization, wavelength, and, in the case of pulsed beams, the duration of the pulses. And not just as an average along the entire beam, but at each point of the beam.
This is especially important in imaging applications, Guo says. "If a beam is not perfect, and there is a defect on the image, it's important to know the defect is because of the beam, and not because of a variation in the object you are imaging," Guo says.
Source: Simpler interferometer can fine tune even the quickest pulses of light
(Score: 2) by takyon on Thursday July 12 2018, @08:52AM (4 children)
What does it mean for telescopes?
When are we going to get our omniphobic mayo jars?
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(Score: 2, Informative) by Anonymous Coward on Thursday July 12 2018, @10:00PM (3 children)
It isn't much help for telescopes, unless perhaps you are aiming lasers into or out of a telescope and this will help you with the optical alignment.
What they're doing is aiming the laser at the edge of a beamsplitter cube, parallel to the beam-splitting surface. This gives you two beams out with interference fringes. This is known as a Gates interferometer, which has been around since the mid-1950s. As an optics guy, this looks to me exactly like a Gates interferometer, but their paper says it is different. Digging into the paper, it really looks like they are splitting hairs on it being different. Since I am not a laser jock, I can't comment on whether using this configuration to characterize ultra-short laser pulses is new or not. The paper does have a nice mathematical treatment of the fringe generation. I wanted to read Gates' 1955 Nature paper to try to understand the differences here, but I haven't been able to get a copy of that yet.
(Score: 2) by takyon on Thursday July 12 2018, @10:14PM (1 child)
https://sci-hub.mu/10.1038/176359a0 [sci-hub.mu]
Reverse-Shearing Interferometry
J. W. GATES
Nature volume 176, pages 359–360 (20 August 1955)
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(Score: 0) by Anonymous Coward on Friday July 13 2018, @02:17PM
Thanks! But I think I'll click on that when I get off work and onto my home computer. ;)
(Score: 2) by maxwell demon on Friday July 13 2018, @04:08AM
Ah, so that's why the lab is supported by the Bill & Melinda Gates Foundation! ;-)
The Tao of math: The numbers you can count are not the real numbers.