It has been found that the field distribution of the particles located between the back and front positions of the front fooal plane of the 4 F system has conjugate relationship with the back fooal plane of the system through transformation of 4 F Fourier lens system. This relationship has unfavourable effect on depth of field and determination of the particle position. The fringe visibility and edge contrast of the particles are improved by the amplifying of the lens system. However, the quality of the particle recording and reconstruction will be reduced if the amplifying of the system is beyond 4 times.