Author Question: Koehler illumination: a. Is best achieved using a tungsten-halogen lightbulb b. Allows the ... (Read 54 times)

kellyjaisingh · **on:** Jun 25, 2018

Koehler illumination:

a. Is best achieved using a tungsten-halogen lightbulb
b. Allows the brightest amount of light to be in the center of a field
c. Adjusts for even light across a field
d. Changes the intensity of the light across a field

Question 2

An object is brought into focus using the 10x objective lens. When the 40x objective lens is moved into position, only a minor adjustment using the fine focus adjustment is required to bring it clearly into focus.

What is the term used to describe lenses with this feature?

a. Parcentric
b. Achromatic
c. Plan-achromatic
d. Parfocal

kxciann · **Reply #1 on:** Jun 25, 2018

Answer to Question 1

ANS: C
A microscope with a nonfixed (movable) condenser should be adjusted for Koehler illumination to achieve the best imaging quality possible for the scope. Koehler illumination makes adjustments in various components of the microscope so that even light is present across a field.

Answer to Question 2

ANS: D
When objective lenses are parfocal, only a minor adjustment using the fine focus knob is required to bring an object into focus when moving from one lens to another. Achromatic and plan-achromatic describe how (or if) a lens corrects for the curvature in a field, thus whether or not only part of or an entire field is in focus at the same time. Parcentric means that an image in the center of a field remains close to the center when a different objective lens is brought into position.