Nano-Holographic Interferometry for In-Vivo Observations - Biomedical Optical Phase Microscopy and Nanoscopy - page 344

Monochromatic
image

Color image

Y

CCD

X

Microscope

Optical axis

Objective lens

Z

Y

Microscopic slide

Scaling compound
Metallic ring
Microscopic slide

Sali ne solution

Marching index

Supporting prism

X

E II

θ c θ c

k I

k I

Parameter Value Note

Polystyrene microsphere diameter D sph 6 ± 0.042 μ m Tolerance specified by the manufacturer

Refraction index of polystyrene sphere n p 1.57 ± 0.01 Value specified by the manufacturer

Refraction index of saline solution n s 1.36 Computed from NaCI concentration for

the nominal wavelength of λ = 590 nm

Figure 17.2
Optical setup utilized in the measurements on nano-sized objects and details on polystyrene
microsphere and saline solution [10] .

wavelength 632.8 nm impinges normally to the face of a prism designed to produce limit-
angle illumination at the interface between the bottom microscopic slide (supported by the
prism itself) and a saline solution of sodium chloride contained in a small cell supported by
this slide. Consequently, evanescent light is generated inside the saline solution. The objects
observed with the microscope are supported by the upper face of the microscopic slide.
Inside the cell filled with the NaCl solution, there is a polystyrene microsphere that is 6 μ m
in diameter. The microsphere is fixed to the face of the slide through chemical treatment of
the contact surface in order to avoid Brownian motions. The polystyrene sphere acts as a
relay lens which collects the light wavefronts generated by the nano-sized objects under
observation. For more details on the polystyrene sphere and the saline solution properties
see the table given in Figure 17.2 .