If you intend to use a SH array in a wavefront sensor as is done on the VATT, NOT, MTT etc., first you need to use a lens to image the telescope (aperture) STOP (usually the primary mirror) onto the SH array.
Usually a pair of cemented doublet achromats in a Petzval style setup suffices to image the pupil onto the SH lenset array.The light incident on the SH array is collimated (ie the pupil image formed on the SH lenset array is telecentric). A laser source and a pinhole are used to create a diffraction limited source to calibrate the SH sensor and pupil imaging relay errors.
These SH wavefront sensors usually use a star as a source to measure the telescope errors. In your case either a diffraction limited pinhole source or a laser coupled to a single mode fiber together with a beamsplitter (cube is probably best) would be used.
However the wavefront error contribution of the beamsplitter needs to be measured.
Now such a setup wherein which the relay lens has to be tailored to suit the f# of each telescope is a lot more complex and expensive than using a simple point diffraction interferometer plate with an array of pinhole sizes so that the correct one can be selected to suit the f# of the telescope being tested.
One merely needs a diffraction limited source a beamsplitter cube and a camera with lens to image the pupil onto the camera image sensor.
Manual for F/5 MMT wavefront sensor:https://www.cfa.harv.../wfs_manual.pdf