You are combining 'LIDAR' and 'image processing'. Thus you may want to look for some TOF (Time-Of-Flight) sensor. These are basically integrated circuits.

One implementation would be the MS Kinect (eg. https://en.wikipedia.org/wiki/Kinect). Though surely not the smallest implementation of all, it may give you a starting point.

Another system available is the following: https://www.vitronic.com/traffic-technology/applications/traffic-enforcement/speed-enforcement/poliscan-speed-mobile.html. Looking at the image you'll have to subtract the red flash and a camera to get an impression of the size. What I did not check is whether this system operates with a laser or with TOF sensors as well.

Hope this helps.

Dear Dreher thank you so much for your explanation

my regards

Some of the smallest LIDAR implementations would be the systems used in the automotive industry, see for an example:

http://leddartech.com/modules/leddarone/

I am very grateful dar Klaus