Re: features visible at low magnification are not "clear" at high magnification

Kevin is correct. But you may not have to have darkfield objectives.
The basis of epi-darkfield is lighting at an oblique angle from the
side. You may be able to duplicate the effect by turning off the main
light source and using another light source aimed at the specimen from
an angle outside the objective.

Aaron


On Mon, 19 Dec 2005 13:36:41 GMT, "Kevin Cunningham"
<smskjd@xxxxxxxxxxxxxx> wrote:

>
>"sanjiv" <shrivastavas@xxxxxxxxxxxxxxxxxx> wrote in message
>news:1134956259.142792.17340@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
>> Dear microscopist,
>>
>> I think i have a relatively simple problem for the experts in
>> optical microscopy.
>>
>> I'm looking at indentation in hard ceramics [opaque material] using
>> simple optical microscope with x10,x20,x50,x100 using yellow light,
>> observing in reflection mode.
>>
>> The problem I have is at low magnification x10 around the indents a
>> ring like feature is visible, however at high magnification x50 or
>> x100 the features is not visible. The lateral size of the indents
>> ranges from 30um to 200um. measurements by different techniques
>> (AFM) the vertical depth of indents range from 2um - expected 15ums.
>> The ring like features ranges in height from few(10-50) nanometers
>> to about 1ums.
>>
>>
>> I would appreciate comments, literature, references etc. explaining
>> this effect.
>>
>> since, images can not be posted, i would gladly give images for indpeth
>> response.
>>
>>
>> thanking you for the help.
>>
>> Warm regards
>> Sanjiv
>>
>
>Sounds like its time to use reflected dark field. You might have to upgrade
>your microscope.
>
>Kevin Cunningham
>SMS
>
.