Applications of a self-developing photopolymer material: holographic interferometry and high-efficiency diffractive optical elements

In this paper the applications of a photopolymerizable holographic recording material are discussed. The holographic recording characteristics of the photopolymer include very high diffraction efficiency in transmission mode and relatively low exposure energy, typically tens of milliJoules. The recording material has a resolution of 3000 lines/mm and there is not distortion of slanted gratings. This allows high inter-beam angles in transmission recording and makes the material particularly suitable for the holographic recording of diffractive optical elements. The implications of the resolution limit and other material properties for DOE fabrication are discussed in some detail and results for the recording of on- and off-axis focusing and beam splitting diffractive optical elements are presented. One of the most significant advantages of this material is that it is self-developing. As well as making ordinary transmission holography and DOE recording more convenient, this makes the material particularly useful for both live fringe and double exposure holographic interferometry. Live fringes can be viewed as soon as any stress is applied to the object. This material's unique self-developing properties also mean that the growth of the diffraction efficiency of a holographically recorded DOE can be monitored as it is being recorded. This type of on-line control is extremely useful in DOE fabrication particularly when controlling the ratio of beam splitters.