Introduction to the Long Range Microscope Kit
This kit is intended for viewing sessile drops in furnaces. It allows the microscope to be placed a considerable distance from the drop. The microscope has a built-in fine focus. The magnification and field of view depend on the distance from the lens to the drop. This distance is called the working distance.
Magnification and Field of View
The camera is optimized for sensitivity and maximum possible magnification. The microscope includes a filter holder for infrared filters. Typical working distances and horizontal fields of view are
1.3m working distance, 20mm field of view
1.15m working distance, 19mm field of view
1.0m working distance, 16mm field of view
1.0m working distance, 12.5mm field of view with 10mm spacer between camera and microscope
Bringing the microscope as close as possible to the drop will maximize magnification and give you the smallest field of view. The working distance can be reduced to 0.5m or less with corresponding increase in magnification. If the magnification is too great, it can be reduced by removing the x2 doubler in the microscope stack.
These fields of view would be large for ordinary contact angle work and, particularly, for pendant drop interfacial tension measurements. However, it is better to use larger specimen volumes in furnance work. You must use a larger volume for sessile drop interfacial tension than for pendant drop interfacial tension, so these fields of view are quite serviceable.
Imaging Bright Drops Against a Dark Background
The software includes a checkbox on the contact angle tab to select a bright (white) drop instead of the normal dark (black) drop. This affects both contact angle and interfacial tension measurements.
Install the frame grabber according to its instructions. Then mount the microscope and camera in front of a target that is easy to focus on, say a printed page taped against a vertical surface. Connect the camera to the frame grabber and start the software. Focus is controlled by the rotating control with the red dot located towards the front of the microscope.