Microscopes A guide to use, general Maintenance, and repair tailored to the Olympus CX-21 microscope
Topics Principles of Operation Diagrams Applications History Safety Operation Preventive Maintenance Common Failure Modes Basic Troubleshooting
Principles of Operation Compound optical microscopes use a light source and a series of lenses and to produce a magnified image of a specimen The light gathering/ focusing capacity of a lens is primarily determined by its surface curvature http://www.education.com/study-help/article/physicshelp-compound-microscope/
Principles of Operation Eyepiece Focus light onto eyes 10x magnification Objective Collect light from the sample and magnify image Labeled with magnification (i.e. 4x/10x) and numerical aperture (i.e. 0.10/0.25) Mechanical Stage Moves the specimen in the x and y directions on the stage
Principles of Operation Condenser Collects light from light sources and focuses it on the specimen Aperture Iris Diaphragm Controls the amount of light that reaches the specimen Coarse and Fine Adjustment Knobs Move stage up and down to bring specimen into focus
Principles of Operation Inputs Outputs AC Voltage Light Source Specimen on stage Magnified image of specimen
Diagrams
Applications To view objects that are not visible to the naked eye For cell counting Used to view cells and diagnose disease: Malaria Roundworms Tuberculosis Dysentery Cryptosporidium Giardia Ring-form trophozoites of P. falciparum in a thick blood smear http://dpd.cdc.gov/dpdx/html/malaria.htm
History 2 nd Century BC: Ptolemy describes a stick that appears to bend in water 1 st Century: Romans experiment with glass and observe objects appear larger when viewed through glass 12 th Century: Salvino D Armante makes first eye glasses 1590: Dutch spectacle makers mount two lenses in a tube to create first compound microscope 1609: Galileo Galilee develops compound microscope with concave and convex lens 1665: Robert Hooke s book Micrographia documents observations through the microscope 1674: van Leeuwenhoek achieves greater magnification allowing observation of bacteria http://www.history-of-the-microscope.org/microscope-history-timeline-design-development-inventions.php
Safety Biological contamination: Gloves Wear PPE Treat all blood and bodily fluids as if they are contaminated Before using, read the owner's manual Grounded electrical connection Location & Storage Do not use under vibration Do not store in high humidity Do not store in dusty areas Keep clean Avoid intense temperatures
Operation Place specimen on stage in bow-shaped lever Choose objective Always start with lowest magnification Adjust aperture iris diaphragm to correspond to objective Turn on light source Bring image into focus with adjustment knobs Adjust stage and light intensity as needed
Operation Working Distance Objective Magnification Working Distance 4X 18.5 10X 10.6 40X 0.6 100X 0.13
Operation Using the 100x immersion objective 1. Before engaging immersion objective (100x), place a drop of oil onto the specimen. 2. Engage the immersion objective Make sure oil is free of bubbles 3. Use ONLY the fine adjustment knob to bring the specimen into focus 4. After use, remove oil from objective front lens by wiping with lens paper moistened with lens cleaner
Preventive Maintenance Daily Preventive Maintenance Clean Objective (after using immersion oil) Body of microscope Yearly Preventive Maintenance Microscope frame Check observation tube: Optical axis Left/right axis Revolving axis Parfocality Resolution As needed Grease replacement parts
Preventive Maintenance Inspection sheet can help serve as a troubleshooting checklist
Common Modes of Failure Electrical/Power Failure Light does not turn on when power switch is turned on Light bulb burned out Objective not placed in alignment Dirty components Eyepiece Objectives Filters Fungus growth due to high humidity General User Error Not in focus Brightness not adjusted properly Objective not rotated fully into secured position
Troubleshooting Electrical Unit If lamp does not turn on when power switch is turned on, there is a problem with the electrical unit, unless
Troubleshooting Electrical Unit If light bulb is not the issue, check that microscope is plugged in and outlet has power (use another device you know to be working to validate this) Verify the cord shows no obvious damage Verify that the fuse is intact
Troubleshooting If the previous steps do not reveal the cause of failure The problem is most likely the circuit board itself Replacing individual components is not feasible, entire board needs replaced If an identical microscope exists that is not usable for another reason, harvesting its circuit board is an option. See the manual for instructions on removing the circuit board
Troubleshooting Coarse/Fine adjustment knobs do not turn smoothly Knobs need to be greased
Troubleshooting Stage falls down spontaneously or an in-focus image quickly moves out of focus Cause: tension on coarse adjustment knob is too loose, needs to be adjusted
Troubleshooting: Stage Movement If the stage does not move smoothly in the x or y directions, the tension of the x/y wires must be adjusted