This paper describes the preliminary design of the so-called Transmit/Receive Optics (TRO) for the ADALIN lidar instrument on the future ADM Aeolus weather satellite. The TRO is the central optical unit of the instrument, that feeds the optical signals from the laser source to the emitting/receiving telescope, and vice versa, the received back scattered signals from the telescope to the spectrometers for Doppler shift evaluation. Additionally, the TRO supports a calibration branch, that bypasses the telescope (from the laser to the spectrometers) and aims at levelling out the received signals in terms of wavelength and signal height changes due to wavelength and intensity variations of the laser. Since the spectral range of the ALADIN instrument is narrow (centred at 354.8 nm), the TRO makes use of refractive optics (lenses) to a high extend. A 1 nm narrow band interference filter has been implemented on the reception branch on the TRO to suppress disturbing background signals. Special features of the TRO are two so-called aberration generators on the emitting and calibration branch, with which an artificial astigmatism can be realised for eye safety reasons. An opto-mechanical concept has been realised with four afocal optical groups, which are connected by parallel beams. Different design options for the aberration generator are being discussed with clear preference of a pure lens solution. The performance of the optical subsystem is monitored by extensive simulations, which are shortly summarised. As a specific simulation example, the analysis and trade-offs of the aberration generator are given.