The big clear end of the image tube will emit electrons where light lands on it (a focused image of your subject). Internal grids will accelerate the electrons to a phosphor screen at the other end. A high positive voltage at the phosphor end attracts the electrons. Part way along the electron path is another grid at about 10% of the phosphor end voltage for focusing the image. I reached in my box of stuff and found a high voltage power supply from an arcade game which could work for the 20kV end.
It uses 36VDC at 120mA but adjusting it will also adjust the HV. Seems like a great DIY electronics project. Of course ready-made portable monoculars are out there for several hundred dollars. This would be handy for a fixed image at night. Your lenses and an IR source would also be interesting.
Schematic and data sheet included. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Parts & Accessories\Vintage Tubes & Tube Sockets". The seller is "tedslater" and is located in this country: US. This item can be shipped to United States, New Zealand, Fiji, Papua New Guinea, Wallis and Futuna, Gambia, Malaysia, Taiwan, Poland, Oman, Suriname, United Arab Emirates, Kenya, Argentina, Guinea-Bissau, Armenia, Uzbekistan, Bhutan, Senegal, Togo, Ireland, Qatar, Burundi, Netherlands, Slovakia, Slovenia, Equatorial Guinea, Thailand, Aruba, Sweden, Iceland, Macedonia, Belgium, Israel, Kuwait, Liechtenstein, Benin, Algeria, Antigua and Barbuda, Italy, Swaziland, Tanzania, Pakistan, Burkina Faso, Panama, Singapore, Kyrgyzstan, Switzerland, Djibouti, Chile, China, Mali, Botswana, Republic of Croatia, Cambodia, Indonesia, Portugal, Malta, Tajikistan, Vietnam, Cayman Islands, Paraguay, Saint Helena, Cyprus, Seychelles, Rwanda, Bangladesh, Australia, Austria, Sri Lanka, Gabon Republic, Zimbabwe, Bulgaria, Czech Republic, Norway, Côte d'Ivoire (Ivory Coast), Kiribati, Turkmenistan, Grenada, Greece, Haiti, Greenland, Yemen, Afghanistan, Montenegro, Mongolia, Nepal, Bahamas, Bahrain, United Kingdom, Bosnia and Herzegovina, Hungary, Angola, Western Samoa, France, Mozambique, Namibia, Peru, Denmark, Guatemala, Solomon Islands, Vatican City State, Sierra Leone, Nauru, Anguilla, El Salvador, Dominican Republic, Cameroon, Guyana, Azerbaijan Republic, Macau, Georgia, Tonga, San Marino, Eritrea, Saint Kitts-Nevis, Morocco, Saint Vincent and the Grenadines, Mauritania, Belize, Philippines, Democratic Republic of the Congo, Republic of the Congo, Colombia, Spain, Estonia, Bermuda, Montserrat, Zambia, South Korea, Vanuatu, Ecuador, Albania, Ethiopia, Monaco, Niger, Laos, Ghana, Cape Verde Islands, Moldova, Madagascar, Saint Pierre and Miquelon, Lebanon, Liberia, Bolivia, Maldives, Gibraltar, Hong Kong, Central African Republic, Lesotho, Nigeria, Mauritius, Saint Lucia, Jordan, Guinea, Canada, Turks and Caicos Islands, Chad, Andorra, Romania, Costa Rica, India, Mexico, Serbia, Kazakhstan, Saudi Arabia, Japan, Lithuania, Trinidad and Tobago, Malawi, Nicaragua, Finland, Tunisia, Luxembourg, Uganda, Brazil, Turkey, Germany, Egypt, Latvia, Jamaica, South Africa, Brunei Darussalam, Honduras.