Parts of the Petrographic Microscope

Question 1

Eyepiece (Ocular Lens)

Answer 1

Magnifies the image of the thin section, typically 10x magnification.

Question 2

Objective Lenses

Answer 2

Provide varying magnification (e.g., 4x, 10x, 40x, 100x) and resolve fine details of minerals.

Question 3

Revolving Nosepiece

Answer 3

Holds multiple objective lenses and allows switching between them.

Question 4

Stage

Answer 4

Holds the thin section and allows movement for precise positioning.

Question 5

Stage Clips

Answer 5

Secure the slide in place during observation.

Question 6

Rotating Stage

Answer 6

Allows 360° rotation of the sample for optical property analysis.

Question 7

Polarizer

Answer 7

Produces plane-polarized light for mineral identification.

Question 8

Analyzer (Second Polarizer)

Answer 8

Used for crossed-polarized light (XPL) observations.

Question 9

Condenser Lens

Answer 9

Focuses light onto the sample for improved clarity.

Question 10

Diaphragm (Aperture Diaphragm/Iris Diaphragm)

Answer 10

Controls the amount of light passing through the sample.

Question 11

Light Source

Answer 11

Provides illumination, typically an LED or halogen bulb.

Question 12

Bertrand Lens

Answer 12

Used for conoscopic (interference pattern) observations.

Question 13

Compensator (Accessory Plates: Gypsum, Quartz Wedge, Mica, etc.)

Answer 13

Enhances birefringence effects and aids in mineral identification.

Question 14

Coarse Focus Knob

Answer 14

Adjusts the stage height for initial focusing.

Question 15

Fine Focus Knob

Answer 15

Allows precise focusing adjustments.

Question 16

Mirror (Older Models)

Answer 16

Reflects external light into the microscope in non-electric models.