Fig. 1. The schematic diagram of CT imaging projection acquisition process

Fig. 2. The schematic diagram of LRTI

Fig. 3. The schematic diagram of LRTI

Fig. 4. The flow chart of projection registration algorithm

Fig. 5. The schematic diagram of LRTI system：R，reflector；NPBS，Non-polarizing beam splitter；APD，avalanche photodiode；PIN，positive intrinsic negative；SMF，single mode fiber；MC Laser，microchip laser

Fig. 6. The schematic diagram of 0.98 km experiment verification：（a）the schematic diagram of experimental scene，（b）the schematic diagram of target model，（c）real system show

Fig. 7. Projection data before and after superposition：（a）multi-angle echoes data，（b）projection data formed after superposition

Fig. 8. Reconstructed images of the target before and after registration: (a) reconstructed image before registration, (b) reconstructed image after registration

Fig. 9. Threshold segmentation of reconstructed images before and after registration: (a) threshold segmentation of reconstructed image before registration, (b) threshold segmentation of reconstructed image after registration