Compound microscope lectures

for the second test

compound microscope parts

game linked in the doc.

Compound microscope stand

• frame/backbone

• stability/rigidity

Compound microscope base

• stability 

• may include a light source, lenses, mirror, field diaphragm 

Illumination - trasnmitted 

• voltage controlled by rheostat

• centerable vs pre-centered 

• diffuser filter - even illumination

Field diaphragm

reduces stray light entering the condenser and slightly affects image contrast

Substage condenser

• gathers and concentrates light to illuminate specimen with uniform intensity

• re-adjust with change in magnification

Condenser 

light diverges into an inverted cone with the proper angle to fill the front lens of the objective 

Aperture diaphragm

when closed, allows for the most contrast on the image.

Numerical Aperture

• ability to gather light and resolve fine detail

• A higher number is better

• aperture diaphragm - typically adjusted to provide a new light cone that matches the numerical aperture of the new objective

Condenser types 

• abbe 

• achromat/aplanat 

Abbe condenser

simplest and least corrected

Achromat/aplanat condenser

corrected for chromatic, spherical, and curvature of field aberrations

• critical color photomicrography

Microscope slide thickness 

• thickness between 0.95 and 1.20mm (typically about 1mm)

• 1.20 mm is too thick to be used with most high numerical aperture condensers (very short working distance)

Microscope stage

• can have nothing

• can be a mechanical stage that move the specimen in X and Y directions

Ocular inscriptions

• wide FOV

• UW and UWF - ultra wide viewfiled

• SW and SWF - for super wide-field

• WF - wide field

H and HE (glasses symbol) - high eye point

• field number - (20/22/24) diameter (in mm) of the fixed diaphragm in the eyepiece

Ocular classification 

• according to lens and diaphragm arrangement 

• Huygenian = negative eye piece

• Ramsden = positive eye piece 

Modified (Kellner) eyepieces

• eye-lens is doublet

• higher eye point

• wider field of view

reticle

the graph/scale looking thing that you typically see with your dominant eye

Mechanical Tube length 

• distance from the nosepiece opening, where the objective is mounted, to the top edge of the observation tubes where the eyepieces (oculars) are inserted

• traditionally fixed - 160mm RMS

Microscope heads

• monocular head - single eye tube

• binocular head - two eye tubes

• trinocular head - two eye tubes and a photo tube