Optical variable image making method and its photocomposition system

Abstract

The production method of optical variable image includes the following steps: using a light source and utilizing imaging system to image the shape diaphragm on homographic optical element to producinga a pair of diffraction light beams; collecting the diffraction light beams on the recording material to produce interference fringe point with a certain shape; moving the position of recording material and recording next interference fringe point, repeating above-mentioned operatino until said method is completed. Said optical variable image phototype setting system includes optical circuit system formed from light source, imaging system before diffraction, homographic optical element and imaging system after diffraction, working table and control portion. Said invention can effectively utilize energy of incident light to implement production of homographic diffraction grating.

Description

technical field [0001] The present invention relates to a method for making an optically variable image and its phototypesetting system, in particular to a method for making an optically variable image by using an interference type optical head as a laser direct writing head, and using laser interference fringe points as laser direct writing points. its device. Background technique [0002] Optically variable images are composed of unit gratings with different space frequencies and grating orientations. For embossed images, they can be molded and plated with aluminum to make them reflective reproduction holograms. The human eye can directly observe the reflected diffracted light from the image against the light source. There are infinite combinations of the orientation and space frequency of the unit grating, so that the optical variable image has the optical characteristics of multiple light-variable effects such as color change, dynamic effect and...

AI Technical Summary

Problems solved by technology

At present, there are mainly two ways to make optically variable images. One is to record holograms that form two-dimensional or three-dimensional images by light interference on a holographic dry plate. , Optically variable images with dynamic effects are very difficult; the other is laser direct writing, in which a computer controls the movement of a fine laser beam on the sample stage, and directly exposes on the surface of the photoresist to carve a continuous relief structure. The beam direct writing method has high requirements for electronic control and mechanical precision. If a grating of 10 mm × 10 mm is designed, the diameter of the focal point of the beam is 1 micron, and the operating speed is 10 mm / s, and the lithography is 500 lines The grating of / mm needs at least 80 minutes. For optically variable images with smaller grating constants and larger areas (such as optically variable images for laser anti-counterfeiting packaging materials), single laser direct writing is obviously not suitable

In U.S. Patent No. 5291317, a method for making a holographic diffraction grating pattern is disclosed. After the incident light passes through the diffraction grating, an aperture is used to block the 0-order light and high-order diffracted light, and the positive and negative first-order lights are converged on the photosensitive material. Forming a holographic diffraction grating pattern, because the light intensity of the diffraction grating is concentrated on the 0th order light, the energy utilization rate of the light source is extremely low, requiring a large power of the light source and prolonging the exposure time. At the same time, this method cannot Inserting an image input device into the optical path makes it difficult to form a variable-shape image encoding effect, and the practical effect is poor

Images