Mastering Microscope Precision For Travel: A Step-By-Step Guide

A travelling microscope is a compound microscope that is fitted on a vertical scale and used to measure small items, distances, and diameters more accurately than with manually-controlled instruments or the naked eye. The microscope can be adjusted vertically and horizontally, and the eyepiece is fitted with fine cross-hairs to fix a precise position, which is then read off the vernier scale. In this article, we will discuss the steps involved in using a travelling microscope, including setting up the microscope, adjusting the focus, and taking measurements. We will also provide tips for maintaining and cleaning your microscope to ensure accurate and reliable results.

Setting up the microscope

Place the travelling microscope near a window to ensure sufficient light. Adjust the levelling screw to ensure the base of the microscope is horizontal. The travelling microscope should be placed on a rigid bed, with two rails to allow for coarse and fine adjustments. Adjust the position of the eyepiece for clear visibility of the cross-wire. The microscope can be moved upward or downward, and the vertical scale vernier constant should be determined. Mark a point on the microscope's base using black ink—this will be point P.

Now, place the item to be inspected on the stage of the microscope base. Use specimen sheets if available. Adjust the microscope until it is vertical and focused on point P to avoid parallax between the cross-wires and the mark. At this stage, you can make rough adjustments by sliding the microscope along the internal guiderail. Look through the eyepiece as you do this, stopping when the specimen is in view. Fine adjustments can be made by tightening or loosening the screw head on the sliding mechanism.

Adjusting the microscope

Adjusting the Base and Levelling Screws:

Place the travelling microscope near a window to ensure sufficient lighting for your observations. Start by adjusting the levelling screw(s) to ensure that the base of the microscope is horizontal and level. This step is important to create a stable foundation for your measurements.

Adjusting the Eyepiece and Focus:

For clear visibility, adjust the position of the eyepiece so that the cross wires or crosshairs are easily visible. You may need to adjust the eyepiece until the crosshairs are focused on the reference mark or specimen. Fine adjustments to the focus of the eyepiece can be made by tightening or loosening the screw head on top of the sliding mechanism.

Adjusting the Vertical Scale:

The vertical scale of a travelling microscope can be moved upward or downward. Before taking measurements, determine the vernier constant for the vertical scale. This will ensure accurate readings. Make a mark (point P) on the microscope's base using black ink. Adjust the microscope to be vertical and focus on this mark, ensuring there is no parallax between the cross-wires and the mark. Take the initial reading on the vertical scale.

The travelling microscope's sliding carriage moves along the internal guide rail, allowing for rough adjustments. Slide the microscope along this rail to position it over the item or specimen you want to inspect. Look through the eyepiece as you move it to determine when to stop adjusting. Fine adjustments can then be made using the screw mechanism.

Adjusting the Stage:

The stage of the microscope is where you place the item or specimen being observed. Ensure that the stage is level and centred under the objective lens. Adjust the height of the stage so that the specimen is at the same level as the objective lens, focusing on different parts of the specimen as needed.

Additional Tips:

• When making fine adjustments, always turn the screw more than the slack in one direction to avoid issues with the slack in the mechanism.
• Take readings in both directions (increasing and decreasing) to compare and ensure accurate measurements.
• Remember to calibrate your travelling microscope frequently to assure accurate readings.

Placing the specimen

To place the specimen in a travelling microscope, follow these steps:

Firstly, ensure you have the correct specimen sheets for your particular model. Place the item you wish to inspect onto the stage on the base of the microscope, using the specimen sheets provided if available. If you are using a glass slab, place it on the horizontal surface of the microscope's base.

Next, adjust the levelling screw to ensure the base of the microscope is horizontal and adjust the eyepiece for clear visibility of the cross-wire. You may also need to adjust the microscope's vertical scale to determine the vernier constant. Mark a point on the base of the microscope using black ink. This will be point P.

Now, place the glass slab with the least thickness over point P. Move the microscope upwards and focus on the image of the cross-mark, which is point P1. Repeat this step for thicker glass slabs, ensuring you record your observations each time.

Finally, to focus on a specific particle, you can sprinkle a few particles of lycopodium powder on the slab's surface. Raise the microscope upwards to focus on the particle and take your readings.

Focusing the microscope

To focus a travelling microscope, follow these steps:

Firstly, ensure you have sufficient light by placing the microscope near a window. Next, adjust the levelling screw to make the base of the microscope horizontal. Adjust the eyepiece for clear visibility of the cross-wire.

Now, determine the vernier constant for the vertical scale of the microscope. Mark a point on the microscope's base using black ink—this will be point P. Make the microscope vertical and focus on point P to avoid parallax between the cross-wires and the mark.

Let R1 be the reading on the vertical scale. Now, place the glass slab with the least thickness over the mark and let P1 be the image of the cross-mark. Move the microscope upwards and focus on P1. Repeat the previous step to get a reading, R2, on the vertical scale.

Sprinkle some lycopodium powder on the slab's surface and focus the microscope on a particle near S by raising the microscope further upward. Repeat the step to get a reading, R3, on the vertical scale.

The microscope is now focused, and you can record your observations.

Taking measurements

To take measurements with a travelling microscope, start by placing the item you want to inspect onto the stage on the base of the microscope. Use specimen sheets if your model includes them. Next, slide the microscope along the internal guide rail to make a rough adjustment. Look through the eyepiece as you do this so you know when to stop. You can tighten or loosen the screw head on the sliding mechanism to make fine adjustments to the focus.

The eyepiece is fitted with fine cross-hairs to help you fix a precise position, which you can then read off the vernier scale. The microscope slide can be clamped at any position using a clamping screw. The microscope can be fitted to a vertical slide, which is attached to the horizontal carriage of the microscope. This allows the microscope to be clamped in a vertical or horizontal position.

To take measurements, turn the slow-motion knobs on the base of the microscope to capture and take readings of the specimen's properties. Make sure to remove the specimen from the stage when you are finished.

It is important to note that travelling microscopes need to be calibrated frequently to ensure accurate readings. The microscope should also be adjusted to ensure sufficient light and a clear visibility of the cross-wire. The vertical scale of the microscope should also be considered when taking measurements.

Frequently asked questions