What do the inscriptions “LWD” or “ULWD” mean on an objective?
These letters identify long or ultra-long working distance objectives where the working distance from the front of the objective to the focused specimen is much longer than it is on standard objectives of similar magnification. Long and ultra-long working distance objectives become invaluable when you want to: look up through a culture vessel or petri dish in inverted biological microscopy, look at a thick metallurgical mount in upright incident light microscopy, examine IC wafers to prevent incident contact, or inspect solder connections of mounted chips.
