Re: Using Sapphire Cover Slip with a Confocal Microscope

From: Aaron (nghy_at_comcast.net)
Date: 03/22/05 

Date: 22 Mar 2005 17:57:03 -0600

Hi,

The information you have supplied is not enough to characterize your
problem completely. Clearly you are working in a very specialized
area of microscopy which requires non-standard equipment.

At high magnifications, the field of view has very tiny dimentions.
You may want to consider scalling down your vessel so the walls are
both thin enough for the objective and strong enough for the pressure,
for instance a fused silica capillary tube or other miniature device.

This link is to suppliers of specialized laboratory glassware for
microscopy.

http://www.olympusfluoview.com/resources/specimenchambers.html

Perhaps one of these may have what you need. I hope it is not a wild
goose chase for you. ;-))

Aaron

On Tue, 22 Mar 2005 10:27:20 -0800, Philip <pcywong@stanford.edu>
wrote:

>Andy Resnick wrote:
>> Kevin Cunningham wrote:
>>
>>> "Philip" <pcywong@stanford.edu> wrote in message
>>> news:d1oc2e$qu0$1@news.Stanford.EDU...
>>>
>>>> If I were to use a confocal microscope to image a sample through a
>>>> sapphire cover slip, will there be problems in terms of resolution
>>>> etc. considering the differences in refractive index, % transmission
>>>> compared to normal 'glass' cover slips? How much worse or better?
>>>> Will fused silica be a better choice?
>>>
>>>
>>> Confocal imaging doesn't explain the problem. The problem you discuss
>>> would be the same if you were using white light. High NA objectives
>>> are designed for 0.17mm of glass, other materials would either
>>> increase or decrease the working distance and give more distortion
>>> since a cover glass is the first lens in an objective. The greater
>>> the NA the less difference in thickness of a glass coverslip.
>>>
>>> What problem are you trying to avoid?
>>>
>> Just to elaborate a bit-
>>
>> Microscope objectives are not only designed with a specific coverslip
>> thickness in mind (0.17 mm = # 1 1/2), but also a specific refractive
>> index and dispersion. So even switching from a glass coverslip to a
>> plastic coverslip, even if the thickness is the same, will introduce
>> aberrations.
>>
>> To be sure, the casual user will not notice this. And, some objectives
>> are corrected for "no coverslip"- usually metallographic objectives, but
>> also water dipping lenses. 'Korr' objectives, with a adjustment ring,
>> are able to compensate for different coverslip thicknesses to some degree.
>>
>> Additionally, sapphire is birefringent, which creates a whole different
>> set of issues. Why are you using sapphire? Thermal issues?
>>
>
>ok. It should be obvious I know next to nothing about optics. (I'm just
>an end user).
>I need a fairly strong material as what I'm imaging is under pressure.
> From my calculation, this would either have to be a 1mm sapphire or a
>2mm fused silica. I have the impression that thinner is better as the
>objective can then get closer to the sample. But it seems like there is
>more to it.
>
>Will there be a difference if I were to use a c plane sapphire (optical
>axis normal to face)which supposedly reduce the birefringence?
>
>
>
>
>

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