Questions tagged [optics]

Behaviour and properties of light, and its interaction with matter, particularly in detection of light.

Filter by
Sorted by
Tagged with
6
votes
2answers
200 views

What makes small interferometers useful? Like NIRISS on JWST

NIRISS is an instrument on the James Webb Space Telescope. It has a "non-redundant aperture mask" which obviously covers most of the area of the sensor. It seems to be advantageous for high contrast ...
4
votes
1answer
406 views

Have there been studies of “old photons” to see just how constant things like Planck constant has been?

The question Are photons aged? and answers therein have got me thinking: I vaguely remember hearing something about experiments where "old photons" were collected by large telescopes from very ...
9
votes
4answers
383 views

Are there any mirrors in space?

We have encountered galaxies that act as lenses, magnifying the light coming from behind them. This is super fascinating and it makes me wonder what other optic tools we might have at our disposal. ...
3
votes
1answer
678 views

How does making a refracting telescope very long reduce the chromatic aberration of an uncorrected lens?

Below are two cropped views of "Johannes Hevelius's 8 inch telescope with an open work wood and wire "tube" that had a focal length of 150 feet to limit chromatic aberration." from ...
2
votes
3answers
215 views

How did Johannes Hevelius' long telescope work? Why all the round holes?

The drawing below, found in Wikimedia and at lib.harvard.edu is of a very long tubed aerial telescope. I believe it is taken from his 1673 work Machinae coelestis. I've always wondered about the ...
2
votes
1answer
855 views

What is the faintest magnitude a telescope can see?

This website claims: The space telescope can detect objects as faint as 31st magnitude... It's referring to Hubble, but does not cite any source or math. How do you calculate the faintest (...
3
votes
1answer
209 views

What is a pupil slicer, and how does it work with anamorphic optics in VLT's ESPRESSO Echelle spectrograph?

This excellent answer points to ESPRESSO, - Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations. From there I looked at the Instrument Description and Performance page. ...
2
votes
0answers
47 views

Within a given image of a multiple-image producing gravitational lens, does Fermat's principle apply?

The question Does gravitational lensing provide time evolution information? is excellent! When we see multiple images of the same object because of the phenomenon of gravitational lensing, do all the ...
7
votes
4answers
367 views

Where exactly is the modification that first corrected the spherical aberration in Hubble's primary mirror?

The April 2015 CBS News article How NASA fixed Hubble's flawed vision - and reputation describes the modification taken to the Hubble Space Telescopes by the Space Shuttle that was used to correct for ...
3
votes
0answers
202 views

Are they really sure this isn't an Airy disk? How was that ruled out?

How do they know that this is a spherical shell of gas, and not just something like an Airy pattern-like artifact produced by the VLT's large interferometric aperture? Image from: https://www.eso.org/...
2
votes
0answers
38 views

How often are wedge prisms used to correct chromatic effects of atmospheric refraction?

Atmospheric refraction (shown below) happens because Earth's atmosphere has an index of refraction that differs from unity. @MikeG's comment mentions that this refraction would have a chromatic ...
2
votes
1answer
165 views

Telescope and its construction

I want to build a reflecting telescope in my home. I've attached a drawing of my plan that contains some explanations of what I understand so far, and highlights the parts of the design for which I ...
1
vote
1answer
74 views

How are “parallel fields” implemented on the Hubble Space Telescope?

The Phys.org news item Hubble is the ultimate multitasker: Discovering asteroids while it's doing other observations mentions the Hubble Space Telescope's use of parallel fields: A couple years ago, ...
0
votes
1answer
77 views

Does anybody recognize this kind of prism?

Supplemental to this answer to Did Edmund Scientific 4¼ inch Newtonians have 90° prisms as secondary mirrors in the 1970's? I was poking around a bit further and ran across this "1960's Edmund ...
0
votes
1answer
64 views

Does this CHEOPS first light image imply bad astronomy?

@KeithMcClary's comment under lousy mirror corrected by software links to Bad Astronomy's First Light for the Exoplanet Hunter Mission CHEOPS Goes Tetrahedral which shows the image below. I understand ...