Answer :
Microscope slide holder. When you observe samples under a light microscope, they will usually be mounted on a glass slide. The slide holder is used to secure your slide in place so you will not inadvertently change its position.The paired knobs below the stage on the right-hand side move the slide holder either forward and back or left and right. These allow you to precisely control the position of the sample on the stageThe scales on the slide holder can be used to determine the position of an object on the slide. Thus, you can find an object, note its location, move to a new position and then later return to the mapped object. The condenser. Below the stage is the condenser which is used to focus light on the sample. On the left side of the condenser is a knob that can be used to move the condenser up or down. In the up position, intense light is focused on the sample while in a lower position the light is less intense and more diffuse. As a general guide, you will usually want the condenser relatively high for looking at stained samples while a lower position may be preferable for increasing the contrast of unstained materials. The condenser also has an iris diaphragm which can be open or closed to control the light on the sample. The diaphragm opening is altered by moving the lever located at the front of the condenser.
Hope this information helps!
Hope this information helps!