What is the Illuminating Wavelength

[MicroMan2]

So I was trying to learn the physics of oblique illumintation so what is this illuminating wavelength and how do I find its value

[Oliver]

Hello,
The illumination wavelength is the wavelwngth of the light used to illuminate the specimen. It is the wavelength of the microscope lamp. You need to know this wavelength in order to calculate the theoretically maximum resolution. The shorter the wavelength, the higher the resolution. Now, there is no single wavelength, however. The visual spectrum goes from about 450nm to 700nm. For doing calculations, the middle wavelength (around 550nm) is used. Certain light sources, such as LEDs, have a more narrow wavelength spectrum. You have to check the datasheet of the LED to figure out the stongest wavelength. Other lamps (halogen) will shift the wavelength based on intensity. So this is often of theoretical value only.
Oliver.

[MicroMan2]

Thanks now i did my calculations and
2(0.65)
---------
(600nm)
Equals to 0.00216666666
I know I'm wrong because the resolution limit is 0.250
So any help.
And thanks for replying

[Oliver]

You got the fraction the other way around.

Resolution = L / (2*NA)
= 600nm / (2*0.65) = 0.46micrometers

compare this to the values in Table 2, here:
http://zeiss-campus.magnet.fsu.edu/arti ... ution.html

Oliver.