The volume holographic correlator (VHC) can store multiple images in the common volume of the storage medium by angular multiplexing based on the Bragg selectivity of volume gratings. During the correlation, all the correlation results between the stored images and the input search argument can be simultaneously got. Each correlation result is represented by the intensity of the corresponding correlation spot. The key technologies and constraint factors of the practical utilization of the VHC are analyzed. The research progresses in suppressing the channel crosstalk by speckle modulation, eliminating the impact of pattern dependent behavior, improving the processing accuracy by multi-sample parallel estimation, and system integration of the read-only VHC are summarized. Parallel processing ability with more than 7500 channels and processing speed up to 138 GHz are achieved in the current portable VHC system. The successful applications in remote sensing image matching and biometric recognition have proved the high speed high accuracy abilities of the system.