The present work involves the use of Laser Doppler Velocimetry (LDV) technique to measure the acoustic admittance of aluminized composite solid propellant (AP/HTPB/Al) by experimentally measuring the instantaneous velocities of the particles of solid propellant during burning while the acoustic pressure oscillations are being imposed. Both velocity fluctuations and pressure fluctuations are measured synchronously. The experiments are conducted under the high mean chamber pressure with incorporation of servomechanism feedback system to maintain the relative distance between the laser probe volume and the propellant regression surface. The probe volume of the laser is maintained at a constant distance from the burning surface by using a linear actuator. It is clear from the literature that only limited work has been reported on LDV of solid propellants and hardly there is any work reported on characterizing aluminized solid propellants at high mean chamber pressure using the LDV technique, which has high spatial and temporal resolution features. In order to accomplish this task, a high pressure window bomb is designed and fabricated with multiple optical access quartz windows. These quartz windows serve multiple purpose of visualizing the propellant burning with the help of camera and allow the laser beam to align over the propellant surface. Two windows in the chamber are in-line with each other so that the He-Ne laser can pass for facilitating feedback loop system. An actuation system is designed which comprises of an actuator that is capable to withstand 6800 N of the dynamic loading and attached to the propellant holder and propellant feed shaft. The actuation system is operated under two modes, viz., open loop mechanism and closed loop mechanism. In open loop mechanism, the actuator shaft is continuously advanced in the upward direction based on the burning rate data obtained using combustion photography. The combustion photography is performed up to the mean chamber pressure of 4 MPa for two aluminized composite solid propellants, which are the industrial grade propellant provided by the DRDL, Hyderabad. In the combustion photography method, videos are captured and processed using the MATLAB code to trace the frame-by-frame displacement of the regression surface of the solid propellant. For the actuator operations, an Arduino code is written in the Arduino workbench platform for controlling the electronic equipment. The Arduino code is written to monitor as well as record the actuator position data. In the closed loop feedback mechanism, a 5 mW He-Ne laser beam is used and focused on the propellant burning surface propellant. He-Ne laser beam is partially blocked by the propellant and the unblocked part of the beam is detected by the photodiode. An Arduino code based on the PID algorithm written in the Arduino workbench is used to accomplish the feedback mechanism. Both open loop and closed loop mean burning rate from LDV have shown good agreement when compared with combustion photography and the strand burning data provided by DRDL, Hyderabad. Tests were conducted for two aluminized composite solid propellants at low frequency ranges (130-312 Hz) of the longitudinal acoustic modes and mean chamber pressures ranging from 1 to 3 MPa. A rotary valve is designed to acoustically excite the chamber to the required resonant frequency. The response function of a solid propellant indicates the inclination of the propellant to cause the acoustic combustion-instability. Both velocity fluctuations and imposed pressure fluctuations are measured experimentally and used to determine the acoustic admittance of the solid propellant and thereby relating it to obtain the pressure coupled response function. It was found that admittance rises with frequency and peaks around 260 Hz and then falls. The use of linear actuator mechanism significantly improves the velocity data rate (number of data points). Maintaining the probe volume at 800 to 900 microns above the propellant surface is very crucial to determine the admittance accurately. Test results revealed that a good agreement between the steady state mean burning rates with the window bomb experiments is achieved. The measured mean burn rates under imposed acoustic pressure oscillations shows the augmentation up to 55%. It can be concluded that the LDV of solid propellant has shown promising result for the aluminized propellant burning rate estimation under steady state combustion for high mean chamber pressure.