A system for real time non-contact structural health monitoring of machine tools is developed. the complexity, cost of acquiring and maintaining the machine tools resulting in need for reduced downtime has attracted the attention of researchers towards the development of structural health monitoring system (shm). a non-contact shm system for machine tools based on the vibration signal signatures collected through a low-cost, microcontroller based data acquisition system has been developed. the vibration signatures of the machine are collected from the array of ldrs. these signals are fed to labview software through a microcontroller connected to ldrs. the vibration signatures are then analysed in a dedicated software developed for this purpose. the vibration signatures obtained through the developed non-contact pick up have also been compared with the signal obtained through contact type i.e. accelerometer and the results have been found to be matching. the various components of the non-contact vibration pick up are: 1. hardware • laser emitter: a laser diode produces a laser beam and an array of photo-diode sensors receives the reflected beam, which is reflected from the reflector placed on the vibrating object for acquisition of vibration data. the angle between the incident ray and reflected ray has been found to be 7.5◦as the sensor arrangement was positioned in front of mirror to prevent any loss of reflected light over the array of light dependant resistors. • vibration rig: an electric motor is fitted in a steel frame. an iron frame has been employed with two assemblies. firstly, the rotor assembly has a pulley and a rotating shaft with an outer diameter, the pulley being mounted for rotation on the rotating shaft (fig. 2).secondly, the stator assembly has a bearing sleeve with a bottom opening, the rotating shaft being inserted into the bearing sleeve for rotation. a 20 mm diameter shaft is supported by another bearing placed at the other end. a belt is also added to rotate the shaft by applying an electric power to the motor (rotates at1100 rpm). • signal receiver: six light dependant resistors (ldr) sensors embedded in a printed circuited board are habituated to receive the vibration signal by studying the change in the intensity of the laser beam. the pcb includes a sensing element and a resistor interface able to carry information from the sensing element and send an analog signal to the microcontroller. a two-dimensional cross-shaped five sensors, i.e., pin 0, pin 1,pin 2, pin 4, and pin 5 are placed together to receive the variation in intensity of laser light due to vibrations, whilst the sixth sensor, i.e., pin 3 is placed at some distance to receive the surrounding light. the pin 3 is positioned separately as to remove the noise (in the form of light) interferences that come from the surroundings during operation. • microcontroller based data acquisition device: a microcontroller (arduino) data acquisition device has been used as a central data acquisition hub. this device helps to interface vibration signals with the computer program using labview installed on a pc via a usb port. using a standard high speed usb port, this device enables low cost, pc basedanalog and digital input/output data acquisition. a microcontroller is associated with the sensor, and brings forth a 2. software two computer programs have been developed in different software developmental environments. the first is prepared for microcontroller called lifa (labview interface for arduino) and the other is based on vi (virtual instrumentation) for ldr sensor in labview to capture and display the vibration signals in real time. 3. integrating and testing of the data acquisition system during the operation, the sensor arrangement was positioned in front of mirror to prevent any loss of reflected light over the array of light dependant resistors. three sets of experiments were conducted on the designed vibration rig for different conditions of bearings to visualize and analyse the vibration data. 4. calibration a contact type triaxial accelerometer embedded in a vibration rig has been used to calibrate the results acquired by the developed system.