Abstract: A lens optical system includes a first lens group having a positive refractive power, a second lens group consisting of two or less lenses and having a positive refractive power, and a third lens group having a negative refractive power. The second lens group is configured to perform a focusing operation to correct a change in an image distance dependent on a change in an object distance, and the first lens group and the third lens group are fixed and the overall length of the lens optical system does not change during the focusing operation.

Abstract: Provided are methods comprising transmitting an authentication request for an operator of an unmanned aircraft system (UAS) to an UAS Traffic Management (UTM) server, transmitting flight plan data to the UTM server if the authentication request is successful, receiving operational data that comprises first traffic data, displaying at least a portion of the operational data, receiving flight data from the UAS, transmitting the flight data to the UTM server, and receiving updated operational data comprising second traffic data based on the flight data.

Abstract: In general, the subject matter described in this document can be embodied in methods, systems, and program products. A computing system receives a token that was specified during a process for logging into an account. The computing system determines whether the token matches any of a plurality of tokens that are assigned to a respective plurality of accounts. The computing system identifies, in response to determining that the token matches a particular token that is assigned to a particular one of the plurality of accounts, a username for the particular one of the plurality of accounts. The computing system provides information to cause a computer display to present the username and multiple other usernames in an obscured manner. The computing system receives an indication that user input selected the username. The computing system receives a password. The computing system provides authorization to log into the account.

Abstract: In general, the subject matter described in this document can be embodied in methods, systems, and program products. A computing system receives a token that was specified during a process for logging into an account. The computing system determines whether the token matches any of a plurality of tokens that are assigned to a respective plurality of accounts. The computing system identifies, in response to determining that the token matches a particular token that is assigned to a particular one of the plurality of accounts, a username for the particular one of the plurality of accounts. The computing system provides information to cause a computer display to present the username and multiple other usernames in an obscured manner. The computing system receives an indication that user input selected the username. The computing system receives a password. The computing system provides authorization to log into the account.