*****
To join, leave or search the confocal microscopy listserv, go to:
http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
Post images on http://www.imgur.com and include the link in your posting.
*****

From your test results, the only components left would be the beam splitter
or the mirrors.  That seems unlikely, but its worth removing each one in
sequence just to be sure you don't have a defective or damaged component
somewhere.

Regarding sted, an achromat is better than a singlet, but probably not
adequate given the large bandwidth you want to use.  I recommend getting a
good microscope objective or even a reflective collimator.  Zemax gives a
0.3 diopter focal shift over that bandwidth for instance.

Mike


On Wed, Nov 5, 2014 at 3:34 PM, Yan, Lu <[log in to unmask]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Hi everyone,
>
> I have updated the linked page a bit, and included some images I took
> yesterday. FYI, the link is:
>
> https://www.evernote.com/shard/s275/sh/55130807-98d4-4748-a4a9-64d19650b695/be0756284a13da18fe6d1f7f419cbcfe
>
>
> Hi Mike,
>
> ​I am using a achromat since we will be doing multicolors (in 500~750 nm,
> ultimately we would like to build a STED illumination system using
> fibers.)​. For the lens orientation, yes I checked that, and there is also
> an arrow mark indicating the direction of collimated wavefront on the lens
> housing. The problem with the aspheric is that, for multiple colors if I am
> not mistaken, I will get significant chromatic aberration provided that my
> objective lens (Olympus UPLSAPO 60X) will have quite good correction on
> chromatic aberration, i.e. it focuses collimated multiple colors on to the
> same focal plane so if I have multiple beams with different divergent
> angles it will focus them at different z positions.  So a good achromat
> seems the only option.
>
> For the coupler alignment, I am using a throlabs 3-x stage (
> https://www.thorlabs.com/thorproduct.cfm?partnumber=MBT616D) with a fiber
> holder. I also tried 6-x stage but it does not give me better results. I am
> using flat cleaved fiber.
>
> I have updated the linked page and added some images of the beam at
> different position in the system. Hope that can clear something out.
>
> Thanks,
> Lu
>
> -----------------------------------------------------
> Lu Yan
> Nanostructured Fibers and Nonlinear Optics Laboratory
> Electrical and Computer Engineering
> Boston University
> 8 St. Mary St., Boston, MA, 02215
> (617)353-0286
> [log in to unmask]
> -----------------------------------------------------
>
> On Wed, Nov 5, 2014 at 1:40 PM, Michael Giacomelli <[log in to unmask]> wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > Post images on http://www.imgur.com and include the link in your
> posting.
> > *****
> >
> > Hi Lu,
> >
> > Regarding your collimator, using short focal length achromats is usually
> a
> > bad idea unless you are using a very broadband laser (E.g. short pulse
> > ti:saph or supercontinuum).  Instead, aspheric couplers are usually used
> as
> > an achromat will have significant spherical aberration.  If you do use an
> > achromat, make sure that do not use it backwards (always minimize
> > glass-wavefront curvature - flatter face into diverging wavefront, curved
> > face into collimated wavefront) and if possible simulate in zemax to be
> > sure before trying it.  Just simulating the AC254-30-A, putting the lens
> in
> > backwards results in a massively abberated beam.  I would double check
> that
> > first.  Alternatively, buying an aspheric may be a better idea.
> Technically
> > the AC254-30-A is ok, but only just, only if perfectly aligned.  You have
> > little margin for error.
> >
> > If you haven't already, I recommend aligning the coupler to the grid of
> > your table, and running the beam quite far out and ensuring that it is
> > truly parallel to that grid (and thus perpendicular to lens face).
> Because
> > of the short focal length, you must be very precise here, with an error
> of
> > about a quarter of a millimeter in centration introducing noticeable
> > astigmatism.  I recommend a good 3 axis kinematic.
> >
> > Regarding tilt of the fiber face, usually fibers are angle cleaved, and
> > then mounted in a coupler with a matching tilt.  Make sure that if you
> used
> > an APC fiber, you have an APC mount, and if you used a flat cleaved
> fiber,
> > you have an un-angled mount.
> >
> > Regarding mirrors, a standard thorlabs mirror used in one of their mounts
> > will have negligible astigmatism when used with a beam of your diameter.
> > It is true that mirrors can and do introduce aberration into beams, but
> > with such a narrow beam diameter, even a relatively poor mirror will not
> > introduce noticeable phase error.  These problems are much more common at
> > 2" and above.
> >
> > By the way, do you have access to a beam profiler?  Taking an image of
> this
> > focal spot and posting it might give some clues.
> >
> > Mike
> >
> >
> >
> >
> > On Wed, Nov 5, 2014 at 1:11 AM, Yan, Lu <[log in to unmask]> wrote:
> >
> > > *****
> > > To join, leave or search the confocal microscopy listserv, go to:
> > > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > > Post images on http://www.imgur.com and include the link in your
> > posting.
> > > *****
> > >
> > > Hi Mike,
> > >
> > > Thanks for promote reply. Like you said for an on axis system
> (especially
> > > simple as mine), astigmatism should not be there, and that why it
> > confused
> > > me a lot. I am currently using a Thorlabs air-spaced achromatic lens
> > > (f=30mm) (
> > http://www.thorlabs.com/thorproduct.cfm?partnumber=ACA254-030-A)
> > > for the collimation. The fiber I have tried are SMF600 and RBG 400,
> both
> > of
> > > which are single mode at 632 nm. I usually looked at the back
> reflection
> > > (from surfaces of the lens) formed interference pattern (concentric
> > rings)
> > > to align my fiber w.r.t. my fiber facet.
> > >
> > > For your comments on my questions:
> > >
> > > 1) I am using the multimode fiber as the pinhole to achieve confocal.
> > > 2) Looking at the beam spot after the collimation lens, it was not
> > changing
> > > much even at several meters away from the lens. The spot changed
> rapidly
> > > around the focal plane if the beam was reimaged through another lens
> > (e.g.
> > > L2 or L3 in the linked page). I think the NA is large enough for the
> > fiber
> > > I am using.
> > > 3) I was thinking maybe the fiber tip is tilted with respect to the
> > > collimation lens plane? Would that cause problem? OR would that still
> > give
> > > me concentric rings pattern centered at my fiber tip (if the fiber is
> > > tilted w.r.t. the lens plane)?
> > >
> > > Thanks,
> > > Lu
> > >
> > > -----------------------------------------------------
> > > Lu Yan
> > > Nanostructured Fibers and Nonlinear Optics Laboratory
> > > Electrical and Computer Engineering
> > > Boston University
> > > 8 St. Mary St., Boston, MA, 02215
> > > (617)353-0286
> > > [log in to unmask]
> > > -----------------------------------------------------
> > >
> > > On Wed, Nov 5, 2014 at 12:37 AM, Michael Giacomelli <[log in to unmask]>
> > wrote:
> > >
> > > > *****
> > > > To join, leave or search the confocal microscopy listserv, go to:
> > > > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > > > Post images on http://www.imgur.com and include the link in your
> > > posting.
> > > > *****
> > > >
> > > > Hi Lu,
> > > >
> > > > In an on axis system like you have drawn there should be no
> astigmatism
> > > if
> > > > the fiber is well centered on the optic.  Assuming you've correctly
> > > aligned
> > > > the collimator, I would think it is some other aberration you are
> > seeing.
> > > >
> > > > Regarding your questions in that linked page:
> > > >
> > > > 1)  It depends on what you want to collect.  4f (or some other
> imaging
> > > > condition) will give you maximum light collection, which is likely
> what
> > > you
> > > > want if you have selected a multimode fiber.  Alternatively, if this
> > is a
> > > > confocal system, it is probably not necessary.
> > > >
> > > > 2)  The diagram shows a collimated single mode fiber.  That should be
> > > > independent of distance.  If you find that your spot is changing
> > rapidly
> > > > with distance, likely something is wrong with the collimation.  What
> > are
> > > > you using a collimator?  Is it suitable for the NA and
> > > wavelength/bandwidth
> > > > of your source?  Is it well aligned?  What is the exact model of
> fiber
> > > you
> > > > are using.
> > > >
> > > > 3)  Most likely it is a problem with your coupler.
> > > >
> > > > Mike
> > > >
> > > > On Tue, Nov 4, 2014 at 11:36 PM, Yan, Lu <[log in to unmask]> wrote:
> > > >
> > > > > *****
> > > > > To join, leave or search the confocal microscopy listserv, go to:
> > > > > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > > > > Post images on http://www.imgur.com and include the link in your
> > > > posting.
> > > > > *****
> > > > >
> > > > > Hi folks,
> > > > >
> > > > > I am building a fiber based confocal microscopy setup (with sample
> > > stage
> > > > > scanning). But I always got some astigmatism aberration in PSF
> > > > measuremnts.
> > > > > The similar aberration was there even I replaced the objective lens
> > > with
> > > > a
> > > > > regular lens and imaged my illumination beam through that lens
> with a
> > > > > camera. I got elongated beam 'spot' on both sides of the focal
> plane,
> > > and
> > > > > the orientation of the two 'spot' were orthogonal. I think that is
> > > > > astigmatism aberration if I am not mistaken. I draw a schematic in
> > > > Evernote
> > > > > so I can include it here. Here is the link:
> > > > >
> > > > >
> > > >
> > >
> >
> https://www.evernote.com/shard/s275/sh/55130807-98d4-4748-a4a9-64d19650b695/be0756284a13da18fe6d1f7f419cbcfe
> > > > > (copy and paste if the link does not work in email)
> > > > >
> > > > > I tried to adjust both lens in xy to avoid off-axis incident, but
> the
> > > > > aberration would go away. So I got confused where they came from. I
> > > hope
> > > > > someone here could lead me a direction to further look into it.
> > > > >
> > > > > Thanks very much,
> > > > > Lu
> > > > > -----------------------------------------------------
> > > > > ​​
> > > > >
> > > > > Lu Yan
> > > > > Nanostructured Fibers and Nonlinear Optics Laboratory
> > > > > Electrical and Computer Engineering
> > > > > Boston University
> > > > > 8 St. Mary St., Boston, MA, 02215
> > > > > (617)353-0286
> > > > > -----------------------------------------------------
> > > > >
> > > >
> > >
> >
>