Optical Features Of Sc Microscope.h - Nikon SC Instructions Manual

IV. OPTICAL FEATURES OF SC MICROSCOPE
Combination of Eyepiece 10xSC (field number 18} with Objective SC series
Objective
Total
Magnifi¬
cation
Numerical
aperture
(N.A.)
Real
viewfield
Depth
of
focus
Resolving
power
Working
distance
(W.D.)
4XSC 40X
0.1
4.5 mm
63.2 Jim
2.8 Jim
28 mm
10XSC 100X
0.25
1.8 mm 10.1 Jim 1.1 Jim
8 mm
40XSC 400X
0.65
0.45mm 0.97jim
0.42jim
0.73mm
100XSC
1000X
1.25
0.18mm 0.33jim 0.22jjm
0.16mm
TERMS DESCRIBING THE OPTICAL FEATURES OF MICROSCOPES
• Total magnification
Total magnification of a microscope is the in¬
dividual magnifying power of the objective
multiplied by that of the eyepiece.
• Numerical aperture (N.A.I
One of the important factors determining the
efficiency of condenser and objective. It is
represented by the formula:
N.A. = n sin a.
Where n is the refractive index of a medium
{air, immersion oil. etc.) between the objec¬
tive lens and the specimen or condenser, and a
is a half of the maximum angle at which the
light rays enter or leave the lens from or to a
focused object point on the optical axis. The
larger the numerical aperture, the brighter and
better resolved the image.
• Resolving power
Capability of discriminating two object points
separated by a minute distance on the image
the optical system produces, dius being taken
as a definition standard of image resolution.
The more minute such a distance, the higher
the resolving power of the optical system.
In relation to the numerical aperture, the re¬
solving power is represented by the value:
X/2 N.A.
where \ is the wavelength of light being used.
• Mechanical tube length
Length from the attaching surface of the ob¬
jective on the nosepiece to the top end of the
sleeve into which the eyepiece is inserted.
• Working distance (W.D.)
Clearance between the front of the objective
and the upper surface of the coverglass, when
the image of a specimen is brought into sharp
focus.
• Real viewfield
Diameter of the circular area of the specimen
actually covered under the microscope.
Real viewfield® Field number/objective mag¬
nification
• Field number
Generally, it means the diameter of the field
diaphragm of the eyepiece.
• Depth of focus
Depth (thickness) of specimen image appear¬
ing sharp, extending above and below the
focused image plane.