Proximity sensor to measure object presence, speed and orientation
I have had good success using IRDA Rx and recessed emitters using a binary code to filter out interference up to 1m transmission and 1/3 m reflection at 100 kbps with 7 parallel sequential emitters and 7 detectors. The trick for my app was to have 1 deg beam width by choice of 6 deg emitter and recessed in a non-reflective hole to reduce aperture window further. .
But yours  is a tricky optical problem that demands good eyesite with cross-eyed emitters at various angles to detect depth of an undefined object without getting distance walls reflecting more than the object and using signal threshold with AGC to capture the reflection fast enough to meet your acuity requirements.
Stereo Vision cameras or fast rotating mirrors such as those used by high value autonomous vehicles is the obvious choice, so I cannot give you any better solution than a plurality of BP narrow beam modulated carriers with a Bandwidth and fast AGC design to capture your objects using an array 1 deg apertures.  We used a PIC CPU with 500 bytes  of careful expert crafted code to detect moving objects with a signature shape which is different, and only 1m/s with parts as small as a resistor lead other as big as a shopping cart.