This is a nice Nikon CF 20x DI interferometry objective. It attaches to an infinity microscope with a coaxial illuminator and gives interferometry bands for extremely fine assessment of flatness--also extremely good for detecting ambient vibrations which will make the bands jump around. This one is in good condition, with a few minor marks on the front element which have no effect on function. This is not an imaging objective--it does produce a good image, but with lower contrast likely because of the integrated interferometry elements.
The item "Nikon CF Plan 20x/0.40 DI Mirau Interferometer Microscope Objective Working" is in sale since Friday, May 28, 2021. This item is in the category "Business & Industrial\Healthcare, Lab & Dental\Medical/Lab Equipment Attachments & Accessories\Microscope Parts & Accessories\Microscope Objectives". The seller is "angry-turtle" and is located in Raleigh, North Carolina. This item can be shipped to United States, United Kingdom, Denmark, Romania, Slovakia, Bulgaria, Czech republic, Finland, Hungary, Latvia, Lithuania, Malta, Estonia, Greece, Portugal, Cyprus, Slovenia, Sweden, Indonesia, Thailand, Belgium, France, Hong Kong, Ireland, Netherlands, Poland, Spain, Italy, Germany, Austria, Bahamas, Israel, Mexico, New Zealand, Philippines, Singapore, Switzerland, Norway, Saudi arabia, Ukraine, United arab emirates, Qatar, Kuwait, Bahrain, Malaysia, Chile, Costa rica, Panama, Trinidad and tobago, Guatemala, Honduras, Jamaica, Antigua and barbuda, Aruba, Belize, Dominica, Grenada, Saint kitts and nevis, Saint lucia, Montserrat, Turks and caicos islands, Barbados, Bermuda, Brunei darussalam, Bolivia, Egypt, French guiana, Guernsey, Gibraltar, Guadeloupe, Iceland, Jersey, Jordan, Cambodia, Cayman islands, Liechtenstein, Sri lanka, Luxembourg, Monaco, Macao, Martinique, Maldives, Nicaragua, Oman, Paraguay, Reunion, Uruguay.