A novel high spatial resolution recording method of far-infrared digital hologram based on vanadium dioxide film

摘要

In this paper we present a novel method to record high spatial resolution far-infrared (FIR) hologram. This method takes advantage of the photo-induced phase transition characteristic of vanadium dioxide(VO_2) film. The light path is off-axis digital hologram recording path, while the VO_2 film is kept in constant temperature in front of the recording high resolution CMOS sensor. In the setup, the far infrared light from CO_2 laser changes the partial transmittance of VO_2 film to visible light, then a read-out visible laser is used to measure the transmittance of VO_2 film, and subsequently the results are recorded by a high resolution CMOS sensor. So that with utilizing the photo-induced phase transition of VO_2 film, we can use CMOS sensor to record far-infrared digital hologram. As the pixel pitch of CMOS sensor is much smaller than tradition FIR sensor, the recorded FIR digital hologram has been much improved. Moreover, the transition speed of VO_2 film is in nanosecond scale which means that far-infrared fast-moving object recording and hologram video could be achieved. In our experiments we used different objects to compare the spatial recording resolution and the experiments prove that our method can record higher spatial spatial resolution than traditional FIR digital hologram. It has the potential to become a more effective FIR digital hologram record method. Further research will focus on the simplified light path and FIR hologram video record and process.