1. Introduction and summary

1.1. WEAVE is a new wide-field spectroscopy facility proposed for the prime focus of the 4.2m William Herschel Telescope. The facility includes a new 2-degree field of view Prime Focus Corrector (PFC) with an Atmospheric Dispersion Compensator (ADC), a 1000-multiplex fibre positioner, a small number of individually deployable integral field units, and a large single integral field unit.

1.2. The facility is expected to be on-sky for 2017.

1.3. The purpose of this document is to specify one of the six blanks required for the construction of the WEAVE Prime Focus Corrector. The following specifications have been discussed with several lens polishers, but further discussions between the Supplier and the Customer and between the potential lens polishers and the Customer will be necessary to validate these specifications.

1.4. Within Schedule 4, certain performance and specification criteria are described. However, if alternative or multiple solutions are available for meeting a given criterion, the Supplier may quote for any alternative provided that the performance of said alternative is demonstrated, in the Supplier's response to the tender, to deliver a performance aligned with the Customer's expectations.