2. Human Cornea
• Raman Spectroscopy is a powerful optical technique for the biochemical characterization
tissues and other biologic media.
• For human cornea, referring from Dr.Bauer ‘s paper, the typical Raman spectra of a normal
human cornea in the higher Raman shift range from 2900 to 3600/cm-1
3. What is Confocal Microscopy?
• First developed by Marvin Minsky and patented as a “microscopy apparatus” in 1961.
•
• A well designed confocal system can be described as “double focusing” system.
• Instead of focusing the light through a pinhole, we focus into a central fiber which has fibers
surrounding it.
• Block out as much unfocused light as possible also minimize as much unfocused light into the
central fiber as possible.
5. •Using 50 microns pinhole in spatial filter
•Beam size ~ 7mm ( Back aperture of
microscope objective is around 7 mm)
6.
7. MODE1 MODE 2 MODE 3 MODE 4
Intensity of light
Onto camera
Strongest Weakest N/A Stronger
than 2
Signal to
spectrometer
Weakest Strongest N/A Stronger
than 1
9. Scaling and Testing Results
USAF image with
50X Objective
USAF image with
10X Objective
10. Group Number
/Element
Number
Line Pairs/ mm Line Width
(micros)
Estimated
Laser Spot Size
(microns)
50X 7/2 143.7 ~3.5 ~ 2
10X 5/1 32 ~15 ~ 10
Scaling and Testing Results
•Tube Length = 200mm with 50X objective gives us the focal length of objective is 4 mm
•The lens focusing beam into fiber has focal length of 200 mm
•So the confocal spot size is magnified by 50X to ~ 100 microns
•Center core fiber has a size of 100 microns
11. Scaling and Testing Results
Image of fibers for microscope glass slide with 50s exposure time with 50X objective
12. Use Nikon 60X water immersion objective for Bio sample like cornea
Test 1: Plastic
Scaling and Testing Results
Plastic
Water drop
60X Objective
