Research And Analysis Towards Deflectometry Based On Portable Devices

With the development of modern optical technology, aspheric and free surface optical components have been widely used in various high precision optical systems and daily life. For the current mainstream optical measuring instruments, they are all of high cost and have some limitations. For the people who have never been systematically studied optical detection, it is unable to start. In addition to the conventional interferometric measurement and the coordinate measuring instrument, the fringe reflection method can be used to reconstruct the surface shape of the incident light. The typical fringe reflection method is a kind of method that uses simple equipment to carry on the high accuracy measurement of the reflective surface. In the past few decades, deflectometry is used for testing the reflection and refraction surface, such as the surface of automotive and aircraft, plastic lenses. It has large dynamic range, high efficiency and it's non-contact.In this paper, the simulation and preliminary experimental verification of the fringe reflection method are carried out by using CCD camera and common LCD monitor. Error introduced from the physical location is analyzed. Proposed to integrate the whole system into a wide range of mobile phones and other smart devices. Mobile phones and tablet computers are generally equipped with front camera, high resolution screen and high-speed processor, meet the basic detection conditions, can be integrated to achieve rapid and easy detection of the surface of the class. In this paper, the advantages of mobile devices are discussed in this paper, and the software and hardware error sources are analyzed. A series of methods, such as camera calibration, improve the phase shift algorithm, grid position calibration, filtering de-noising, automatic gain adjustment and so on, are proposed to improve the measurement accuracy and stability.In addition, this paper designed an app based on the iOS platform to detect the mirror running process. The use of iPad to detect the actual reflection surface, verify the feasibility of the smart camera equipment for measurement. This method has high sensitivity and large dynamic range, and the accuracy can reach micron level. This method is low cost and high flexibility, and is a widely used method for detection.