Introduction to the Microscope Care Parts Focusing
An instrument that magnifies or makes tiny objects look bigger Two kinds: –Simple – contains only one lens –Compound – two or more
2 set lenses Choice of lens magnification
This is a compound light microscope. It is called this because it has two or more lenses (the eyepiece lenses and the objective lenses), and makes use of light to produce an image. Mechanism for enlarging an image
Eyepiece Body Tube Revolving Nosepiece Arm Objectives Stage Stage Clips Coarse Focus Fine Focus Base Diaphragm Light source Magnification Supports body tube Supports slide Focuses image Sharpens the image Supports microscope Reflects light towards eyepiece Regulates amount of light Holds slide In place Magnification Hold objective rotates to change magnification Maintains proper distance between lenses
the eye the image the specimen Each lens magnifies the image, increasing its overall size A lens is a bi-convex disk that bends light The farther the light rays are bent, the larger the image appears The bent rays produces an image
the eye the image the specimen As the light rays are spread farther apart, the clarity or resolution of the image decreases Resolving power: A measure of the ability of a lens or optical system to form separate and distinct images of two objects with small angular separation. Light microscopes are limited in their magnification by their resolving power!
the eye the image the specimen The image is always seen upside down and backwards from its actual position
Place the Slide on the Microscope Use Stage Clips to hold slide in place Open the diaphragm (shutter) and switch on the lamp power A microscope has several lens and each magnifies the specimen like a magnifying glass The magnification of the eyepiece is 10 times (10x)
The two lenses are called: –E–Eyepiece –O–Objective The eyepiece has a magnification of “10x” The magnification of the objective lenses vary and are marked on the lens Total magnification = (Eyepiece) X (Objective) Example: 10 X 40 = 400
Ocular lens Objective lenses 3 objective lens are 4X, 10X and 40X
Always start with the low power objective (4X) Always focus using the coarse knob, then the fine focus knob. Centralise what you want further magnified Switch to the 10X objective lens and if needed, to the 40X objective lens
Follow steps to focus using low power At high power, use only the fine focus knob! Click the nosepiece to the longest objective Do NOT use the coarse focusing knob as it will crack the slide. Use the fine focus knob to bring the slide
Do NOT remove the slide as it is very close to the objective lens. To remove slide, switch to low-power or mid-power objective lens. What will you find?
Eyepiece Arm Stage Course adjustment Fine adjustment Base Let’s Review! Body tube Nosepiece Low power High power Stage clips Diaphragm Light source Medium power
Always carry with 2 hands – one hand on the arm, the other on the base Only use lens paper for cleaning Do not force knobs Always store covered Keep desk clear of objects and cords