Scope Tutorials
The majority of the teaching labs in the Life Sciences Building use basic transmitted light microscopes with the standard 4x, 10x, and 40x objective lenses. A number of histological stains are used to create contrast between different structures in a sample, whether that be individual cells or entire tissues. Our prep lab contains many of these stains for basic light microscopy.
If you encounter issues when using a microscope, please refer to some of the notes below. For the teaching scopes, lab assistants and graduate assistants should be handling any maintenance necessary. Students do not need to troubleshoot their own microscopes for risk of further damage to the objective lenses. Anything beyond the capability of lab assistants should be set aside for service. Notify Daniel Doucet (doucet@shsu.edu, LSB office 200K) for service on teaching scopes
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No light is being emitted
This can either be the easiest fix for a teaching scope or the most hopeless. First it is important to check the power cord and the outlet it's plugged into. Make sure another scope of an identical model functions fine with the same cord and outlet. Next, make sure the condenser lens is open, and the bulb is receiving sufficient power to generate light. Proceed with maintenance.On scopes that use a halogen bulb, simply replacing the bulb takes only a minute and is often the culprit. This includes models such as the Olympus CX21 / CX31 and the Nikon Eclipse E200. Below are instructions for replacing the bulbs on these models. Other models require a more intensive disassembly and should be left for servicing. Scope models such as the Olympus CX33 use a longer-lasting LED to generate light which should not require regular replacement.
Olympus CX21 / CX31
These two models are already very similar, and their halogen bulb replacement is nearly identical. Remove the power cord and gently lay the scope flat with the oculars facing upward - making sure to take off any slides that could come loose during the process. A panel on the bottom of the scope is sealed by a small piston. Pull the piston to release the door holding the halogen bulb housing. Take the old bulb out, and when replacing with a new bulb, cut the connector end of the bulb casing and insert it into the housing without touching the bulb with your fingers to prevent oils from accumulating on the glass. Alternatively, use gloves as you replace the bulb. Close the housing door and press into the piston to secure the housing. Test the new bulb.
Nikon Eclipse E200
Remove the bottom condenser lens to reveal the bulb housing by sliding the black portion out. Remove the blown halogen bulb. As noted above, replace the bulb without touching the glass with your fingers, either by keeping it in the casing while attaching, or attaching with gloves. Test the new bulb. -
Image will not focus
Several factors could be influencing an inability to focus, some of which are easy to rule out - and some more involved. Follow the flow chart below to determine the cause of a blurred image. When adjusting coarse and fine focus, try to adjust quickly to help indicate which direction grants a clearer picture. When focusing slowly, our eyes often cannot notice subtle changes. This is not an exhaustive list of possibilities, but includes the most common errors. Basic adjustments such as the opening of the condenser and the correct setup of the sample slide are good first checks before going through a more thorough examination.
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Part of the scope is loose
Sometimes the mechanisms on a scope will wear and loosen from constant use. Two primary regions of the scope may need to be adjusted carefully, and not all scopes will be equal in this regard. If the following maintenance does not resolve the issue, set the scope aside for service, as internal parts may need to be greased or replaced.
Fine / Coarse Adjustment Knobs
If the knob connections feel stripped, or there's no stage movement from turning the fine or coarse adjustment knobs, you may need to tighten them. Facing the back of the scope, hold both knobs. Keep the right knob still and slowly tighten the left adjustment knob as desired by twisting it toward you. Only tighten the level that needs adjustment - if the fine adjustment knobs are loose but the coarse adjustment knob is working fine, only tighten the fine adjustment.
Loose Headpiece
If the headpiece is swiveling, it will need to be tightened. Most scopes will have the attached bit for tightening the headpiece screw, though if one is absent, a bit can be borrowed from an identical scope. Please do not attempt to tighten using a bit from a different model scope - this risks stripping the screw on the headpiece and requiring service.