1. Chapter 7 The Microscope

2. 1. Ocular lens
2.Revolving nosepiece
3. Lower power objective
4. Medium power objective
5. High power objective
6. Stage clips
7. Diaphragm
8. Light source (illuminator)

3. 9. Eyepiece
10. Arm
11.Stage
12. Coarse Adjustment
13. Fine Adjustment
14. Base

4. 1. Ocular Lens: Lens within the eyepiece
2. Revolving Nosepiece- contains the objective lens
3. Objective Lenses: lens directly over specimen; low, medium and high power
4.Stage- supports slide
Stage clips- secures slide on stage.
5. Diapraghm (condenser)- focuses light on specimen

5. 6. Light source (illuminator)- source of artificial light
7. Arm: upright structure which supports microscope
8. Base: Supports microscope
9. Body tube: allows light can pass through to go to each lens
10. Coarse Adjustment: focus an image under low power
11. Fine Adjustment: focuses an image under medium and high power

6. Compound Light Microscope
How is it used?
Light passes through translucent specimen to view internal structures.
When is it used?
On translucent or thin specimens.

7. The Compound Microscope

8. The Comparison Microscope
How is it used?
Two independent objective lenses joined together by an optical bridge to a common eyepiece lens.
Can view two different items simultaneously
When is it used?
Firearms examination
Trace evidence (hair, fibers, etc)
THE MICROSCOPE

9. The Stereoscopic Microscope
How is it used?
Two monocular compound microscopes
Three-dimensional image of a specimen
Use both eyepiece lenses
When is it used?
Evidence not requiring very high magnification (10x–125x)
Microscopic examination of big, bulky items
THE MICROSCOPE

10. The Microspectrophotometer
How is it used?
Spectrophotometer coupled with a light microscope.
Can simultaneously obtain the visible absorption spectrum or IR spectrum of the material being observed
When is it used?
Trace evidence, paint, fiber, and ink evidence.
THE MICROSCOPE

11. The Scanning Electron Microscope
How is it used?
(SEM) bombards a specimen with a beam of electrons instead of light
Produces a highly magnified image from 100x to 100,0000
Depth of focus 300X better than optical systems at similar magnification
Bombardment of the specimen’s surface with electrons
Produces x-ray emissions
Characterize elements present in the material under investigation
THE MICROSCOPE

12. When is it used?
Get a very magnified image

13. Dental Plaque

14. Bread Mold Aspergillus sp.)

15. Penecillium sp.

16. SEM: Hair and Hair follocles

17. SEM: hafnium nitride interface coating on carbon fibers

18. Dust Mite Family Reunion

19. Important Terms
Field of View: area of specimen that can be seen after its magnified
Depth of Focus: thickness of specimen entirely in focus under microscope
Polarizer: devise that permits the passage of light waves vibrating in only one plain.
Parafocal: can change objective lens and field of view will remain in focus

20. Monocular: microscope with one eyepiece
Binocular: microscope with two eyepieces
Virtual Image: image that is magnified (cannot see it directly)
Real image: image seen directly

21. 5. What happens to a compound microscopes field of view when you increase the magnification?
Field of view decreases
6. When using a comparison microscope why is it important to closely match the optical characteristics?
Ensure both specimens are seen at equal magnification and with minimal but identical lens distortions.
7. What is the most frequently used and versatile microscope found in the crime lab? List 3 reasons why this type is so widely used
Stereoscopic microscope because of wide field of view, great depth of focus, large working distance