2.3 Laser reference equipment
In the three-bogie track inspection car, the length of the car body was
as short as 17.5 meters, and track displacement was calculated by
increasing the rigidity of the car body and using the car body as a
reference. The two-bogie inspection car uses a normal car body with
bending flexibility, so the deflection of the car body would cause an
inspection error. Laser light is passed through the floor, and this is
used as a reference for measurement.
The device comprises the phototransmitter of a He-Ne gas laser beam
expander, multiple photoreceivers using a PSD, and a light blocking