# User:Pranav Rathi/Notebook/OT/2010/12/10/Olympus Water Immersion Specs

## Water immersion objective details

WE are using Olympus UPLANSAPO (UIS 2) water immersion IR objective for DNA stretching and unzipping. The detail specifications of the objective can be found in the link:[1] Other specification are as follows;

 Mag 60X Wavelength 1064 NA 1.2 medium water Max ray angle 64.5degrees f # 26.5 Effective FL in water 1.5 to 1.6mm (distance between the focal spot and the exit aperture surface) Entrance aperture diameter 8.5mm Exit aperture diameter 6.6mm Working distance .28mm Cover glass correction .13 to .21 (we use .15)

### Resolution and achievable spot size

The resolution and the spotsize (beam waist) presented here is in the theoretical limits; we cannot achieve better than this. Resolution and spotsize are diffraction limited and to reach these limits our optics has to be perfect; no aberrations and other artifacts. Since our optics is not perfect and very clean we can hardly reach these limits in real life; definitely the resolution and spotsize in real is worse than the numbers presented here. A good way to do a quick estimation of the resolution (diameter of the airy disk) is that its 1/3 of a wavelength λ=.580 μm; λ/3*n= 145 nm. Since we do all our experiments in water we will have take index of water in account (n=1.33). I am ignoring the NA of the condenser in the calculations.

• Wavelength of the visible light λv = .590μm.
• Wavelength of the IR λIR = 1.064μm.
• Diameter of the incident beam at the exit pupil (D=2ω'o.)=6500μm. (ω'o is the incident beam waist)
• Focal length of the objective f=1500μm.
• Angular resolution inside water:
$\mathrm{\theta} = \sin^{-1}\frac{1.22\lambda_v}{nD}= 8.1e^{-5}rad$
• Spatial resolution in water;
$\mathrm{\Delta l} = \frac{1.22f\lambda_v}{nD}=$