Question

Kohler Illumination Questions

a) what do you look at to tell whether the condenser is in focus?

b)how do you focus the condenser?

c) how do you centre the field diaphragm ?

d) how wide should the field diaphragm be open?

e) what do you do in order to see an image of the condenser diaphragm?

f) how do you centre the condenser diaphragm?
g) how do you alter the diameter of the condenser diaphragm ?

h) how wide should the condenser diaphragm be open?

I) what is in focus with your eye?

Answer 1

a)what do you look at to tell whether the condenser is in focus?

One should look at iris diaphragm control to tell that the condenser is in focus.

b)how do you focus the condenser?   

1.condenser front lens is approximately 0.5cm from the bottom of the coverslip.

Using the field iris diaphragm control, located on the front surface of the substage optics, close the diaphragm right down while looking at your monitor.You will see a dark circle encroaching on the screen.

2.If this dark circle does not fall within your field of view, you may need to use the two silver adjusting screws on the condenser arm to centre your condenser.

3.Move the condenser up or down until the edge of the dark circle (the blades of the iris) appears in sharp focus on the monitor.

4.Once you have positioned the condenser correctly switch the user interface back to position (I) to avoid accidental re-positioning of the condenser.Depending on the working distance of the condenser you may be in a close proximity to the sample.

5.Located on the condenser arm are two silver adjusting screws used for centering the condenser.

6.Turn the screws to centre the now multi-edged shape. It should now appear in the centre of the field of view.

c).how do you centre the field diaphragm ?

1.Focus the specimen using the Specimen Fine Focus slider, and then use the Condenser Height slider to bring the field diaphragm iris leaves into focus.

2.Next use the Condenser Lateral Adjustment sliders to translate the field diaphragm iris opening to the center of the viewport.

3.Finally use the Diaphragm Opening Size slider to open the field diaphragm to its maximum size. If the diaphragm opens off-center, use the x-translation and y-translation sliders to bring the opening into the center of the field. Alternatively, the mouse cursor can be placed in the small window (containing a set of cross-hairs) and used to drag the image of the field diaphragm (appearing as a white circle) into the center.

d)how wide should the field diaphragm be open?

80%

e)what do you do in order to see an image of the condenser diaphragm?

Open the condenser diaphragm, the working numerical aperture of the microscope increases, resulting in greater resolving power and light transmittance. Parallel light rays that pass through and illuminate the specimen are brought to focus at the back focal plane of the objective, where the image of the variable condenser aperture diaphragm and the image of the light source will be seen in focus.

f) how do you centre the condenser diaphragm?

Center the image of the field diaphragm using the condenser centering knobs. Open the diaphragm until its edges are barely outside the view field of the microscope. Adjust the contrast by adjusting the condenser diaphragm and adjust the illumination intensity.

g)how do you alter the diameter of the condenser diaphragm ?

Altering the Field Diaphragm Diameter and Aperture Diaphragm Diameter sliders which is utilized to adjust the opening size of these iris diaphragms. As the sliders are moved to the right and left, changes in the diaphragm apertures affect the path of ray traces through the condenser lens system, ultimately influencing the effective working numerical aperture of specimen illumination.

h)how wide should the condenser diaphragm be open?

50-80% wide

i)what is in focus with your eye?

Your eye should be between 10 and 20 centimeters away from the tube for the best observation.