MICROSCOPY & IMAGING
high-touch areas on microscopes, so for shared environments, we recommend a solution of 70% ethanol to 30% water sprayed onto a cloth to wipe down the microscope components, such as focus knobs. T is ensures a suffi cient contact time to disinfect the components. Be sure to follow proper hand hygiene as well, so you don’t contaminate a microscope immediately following its disinfection. Wear gloves during the cleaning process and discard them after you are fi nished. Wash your hands with soap and hot water for at least 20 seconds or use an alcohol- based hand sanitiser with at least 60% alcohol if soap and water isn’t immediately available to you. Optical components require a bit more specialised care. To help prevent scratches on coatings and optical glass, remove dirt and dust that sticks to their surface with an air gun or blower brush. T is way, you aren’t pressing them into the optical
surface when you make contact with the glass. Cotton tipped swabs
are great from a precision standpoint, but they can be a little abrasive on special
surfaces. Speciality swabs designed for use in clean rooms are an ideal solution, but they tend to be costly. You can make your own cleaning swab using a bamboo stick and a piece of lens paper. First, lay out a piece of lens paper on a clean, dry surface. Place your bamboo stick on top of the lens paper and then fold the paper in half so that the tip of the bamboo stick is covered. Next, fold the left edge of the lens paper and begin rolling the bamboo stick until the paper is rolled entirely around the stick. T at’s it! If you choose to use a solvent during your cleaning process, don’t immerse the swab into the solution as this will compromise the integrity of your lens paper. Instead, use a dropper or a transfer pipet to apply a small drop of solution to the swab. You can use lens cleaner or 100% ethanol on your cleaning swab. We recommend you store your ethanol in a container of dri-rite or other anhydrous environment so that it doesn’t absorb water, as this will cause streaking on your optic. T e intention here is to remove oils, not disinfect, so the higher ethanol content is preferred for its quicker evaporation times. Gently wipe the front surface of the lens in a circular motion from the centre to
Green algae colonies from an agar plate captured with an Olympus BX50 using a wet mount at 100x magnifi cation with brightfi eld. Image courtesy of Sally Warring
the edge. Repeat as needed with a fresh cleaning swab—you don’t want to reuse them. To get a clearer view of your optical
surface, you can remove one of the microscope objectives and a single eyepiece. Turn the eyepiece around and look in the ‘wrong-end’ so that it can be used as a loupe. Hold them both up to your eye near a room light and move the objective until you catch a refl ection. Oil immersion objectives will likely
require more frequent cleaning than air objectives. It’s important to clean immersion oil from your objective if the lens won’t be in use for a period of time so the oil doesn’t dry out and collect dust. T is will degrade your image quality even with fresh immersion oil applied on top and could potentially be damaging to your expensive optics! At the same time, you also want to avoid
over-cleaning your objectives. T is can damage the optical cement that holds the top lens element in place, resulting in oil seepage under the top lens. T is will distort the images created by the objective and they’ll need to go back to the manufacturer for repair.
TROUBLESHOOTING PROBLEMS If you can’t see an image when you turn on your microscope, there are a few things you want to check fi rst. Start at the light source and trace the light as it travels to the objective. Are there any mechanical barriers in place, like shutters, sliders, or switches that could be completely or partially in place in the light path blocking the light? Partial obstructions like this are very common and usually present as dark, crescent-shaped artifacts. If you can see the
light coming out of the objective lens, then that’s not where the problem is coming from, and we can look at a few more things. If you’re using fl uorescence, check to make sure that the right fi lters and dichroics are in position, especially if using a manual microscope where these components are not automated. Also check to be sure that the emission light path is directing the light to the right component. It should be sending light to the eyepieces if viewing by eye or to the camera if viewing your image on a screen. If you can see the light coming out of the objective, but you don’t see an image at the detector itself or through the eyepieces, then the problem is likely between these two components. You can check the emission path by using a known sample. Plastic fl uorescent slides are a popular choice. If you’re imaging on a detector, check the exposure or gain to make sure that you would expect to see a signal at the settings you are using. With these few tips, you can trust that
your microscope is producing quality images. Routine care is an essential part of a microscopy workfl ow, and we recommend routine cleaning procedures be performed as needed and that preventative maintenance visits be scheduled on an annual basis. A small investment in time caring for your microscope will keep it functional for years to come.
Lauren Alvarenga is with Evident Scientific.
www.evidentscientific.com
www.scientistlive.com 57
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