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José,

just for completeness, there is a third option for scanning in xy:
When Davidovits and Egger (1969, 1971) built the first confocal laser(!) 
scanning microscope, they used movement of the objective lens for 
scanning. (Dois: 10.1364/AO.10.001615 and 10.1038/223831a0).
I guess there are reasons though, why this approach was not followed up 
by later constructions.

Steffen

On 29.07.2013 10:13, DINTINGER José wrote:
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> To join, leave or search the confocal microscopy listserv, go to:
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>
> Dear all,
>
> Thanks a lot for your help, that made things much clearer for me;
> My project is just starting so I still have to sort out what are exactly the specs we are targeting and do some estimations to evaluate how the problem of vignetting is detrimental.
>
> Really thank you, that was quite helpful... I'll probably come back to the LIST with some more questions!
> Have a nice day.
>
> José
>
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[log in to unmask]] On Behalf Of Peng Xi
> Sent: jeudi 25 juillet 2013 15:05
> To: [log in to unmask]
> Subject: Re: design of XYZ scan system
>
> *****
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> Guy has explained it very clear. ONe thing to add: you may want that the eyepiece image at the same focal distance with your confocal, so the position of objective is fixed. If you only consider doing a z-section within a few hunderds of microns, then you will find that the telescope composed by the tube lens and the scan lens will give you such tolerance (depth of focus) for you to do so, especially if you take the compromise between the two close-by galvos.
>
> Cheers,
> Peng Xi
> Ph. D.    Associate Professor
> Dept. of Biomedical Engineering, College of Engineering Peking University, Beijing, China
> Tel: +86 10-6276 7155
> Email: [log in to unmask]
>
>
> On Thu, Jul 25, 2013 at 7:53 PM, Guy Cox<[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
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>>
>> José,
>>
>>             You are quite right about the problem.  You just have to
>> decide what compromises to make.  Ideally both X and Y scan mirrors
>> should be imaged on the BFP of the objective and several manufacturers
>> have achieved this by appropriate optics, while others have just opted
>> to have them close-coupled and accept the compromise.  If you are now
>> going to focus by moving the objective rather than the stage the risk
>> of vignetting obviously increases.  On possible 'solution'  (or
>> compromise) would be to introduce intermediate optics to make both
>> scan planes telecentric  so that then the objective movement is the
>> only problem.  I think you could get away with this in most cell biology cases.
>>
>>                                                                   Guy
>>
>> -----Original Message-----
>> From: Confocal Microscopy List
>> [mailto:[log in to unmask]]
>> On Behalf Of DINTINGER José
>> Sent: Thursday, 25 July 2013 6:32 PM
>> To: [log in to unmask]
>> Subject: design of XYZ scan system
>>
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> *****
>>
>> Dear all,
>> I'm currently working on the design and fabrication of a cheap compact
>> confocal microscope and I have a question regarding the design of the
>> scanning system. For practical reasons, the ideal solution for me
>> would be to keep the sample stationary and scan the laser beam focus
>> in the XYZ directions.
>> After looking through the literature, I was thinking to use the
>> standard design consisting of  2 closely spaced galvo mirrors for the
>> XY scan , and move the objective in the axial direction for the Z
>> stacks. However I am not sure whether these 2 approaches are
>> compatible; from what I read it seems this is the case but there is a point that confuses me.
>> Indeed, the proper positioning of the galvo mirrors requires that
>> their pivot point is imaged on the back focal (telecentric) plane of
>> the objective via a scan lens and tube lens, meaning that the distance
>> between the mirrors and the back focal plane of the objective must
>> remain fixed. On the other hand, if I move the objective
>> (independently) to adapt the Z-position of the focus, it would mean
>> that the mirror-objective distance is changed...
>> I hope my question makes sense and I'd really grateful for any help.
>> Many thanks,
>> José
>>
>> José DINTINGER
>> Research scientist
>> BioMEMS Section
>> ---------------------------------------------------
>> CSEM Centre Suisse d'Electronique et de Microtechnique SA Jaquet-Droz
>> 1 | Case postale | CH-2002 Neuchâtel www.csem.ch
>>
>


-- 
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Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Walter-Brendel-Zentrum für experimentelle Medizin (WBex)
Head of light microscopy

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