Hi Filipe
Zitat:
Hi Daniel,
Is the image curvature you mention from the optics inside the spectrograph?
Yes.
Zitat:
It could possibly be caused or made worse because of the light not going through the objective/collimator parallel to the optical axis..
I think, I do not realy understand this.
Zitat:
Does it make sense that by replacing a small doublet (working as objective and collimator) by a larger optical assembly (possibly a photographic objective) of the same focal distance that the image could be better corrected?
Yes! Optical systems have some importante parameters. One of thies is refractivity. In general aberrations will be reduced, if the refractivity of the system is spread to many surfaces. So, an objective with many lenses is better corrected. It is always a quastion how good a system must be corrected. In the case of a littrow as an astronomical spectrograph a doublet is good enough for the most applications.
Zitat:
And what about distance of the grating to the objective/collimator? I imagine that the closest they are, light goes less "off-axis" from the optical axis, however it goes in at a slightly greater angle..
Should be small as possible. In the case of a littrow not so good realized.
Zitat:
Would problems increase if the focal length of the collimator/objective would be longer or shorter?
The aberrations increas in general if the focal lenght decreases, specially spherical aberration. But focal length and aberrations must always be treated in context with the diameter of the optic. The F-number is more meaningful. Small F numbers, fast optics are in general worse corrected.
Registrieren
Anmelden
FAQ
Suche
