Layout and fiber capacity of the 2 × 2 NIR detector mosaic. The focal plane consists of a 2 × 2 mosaic of four detectors (each 640 × 512 pixels with a 20 μm pixel pitch) within a mechanical envelope of 61.22  ×  61.22 mm². The total effective light-sensitive area measures 25.6 mm (dispersion) × 20.48 mm (spatial). Along the spatial direction, a single detector accommodates 53 fibers, yielding a total capacity of 106 fibers for the entire mosaic, which satisfies the multiplexing requirements for multiobject NIR spectroscopic observations with the spectrograph prototype.