Will the optical heads operate with both SM and MM fiber?

Yes, you can operate the Keysight Technologies optical heads with both single mode (SM) and multimode (MM) fiber.

All optical heads have a large area (mostly 5mm diameter, some are 3 mm) detectors inside. Although the beam will travel through air, the size of the detectors allows detection for both SM and MM fiber.

Please note that the optical heads need a connector adapter if you want to plug your fiber into the head.

Available connector adapters for both the 8152x and the 8162x optical heads are:
81000AA - Diamond HMS-10
81000FA - FC/PC/SPC/APC
81000GA - NEC D4
81000KA - SC/PC/APC
81000PA - E-2000
81000SA - DIN 47256/4108
81000VA - ST
81003LA - LC
Keysight Technologies also offers a bare fiber adapter to use with either the 8152x or the 8162x optical heads. The model number is 81000BA. This bare fiber adapter is for fibers with a cladding of 125 micrometer.
Available connector adapters for the 8162x optical heads are:
81003FD - FC/PC
81003TD - MTP
81003PD - MPX
81003JD - MT-RJ
81003MD - MU

If the connector you use is not listed, you can either use a patchcord or use the 81000ZA blank adapter.
The 81000ZA is a cap which fits onto the optical heads. You will need to do the machining yourself to have your connector fit in there.
A third option is to design your own cap. The thread size of the optical heads is M32 by 1 mm (pitch) by 3 (rotations).