|
Lightwave, as a kind of electromagnetic wave, possesses a frequency much higher than the response frequency of the current photodetectors, so the complex amplitude of the lightwave cannot be measured directly due to the loss of the phase information. Some invisible optical concepts such as phase, wavefront etc. are difficult to understand for the undergraduate students. To make the wavefront of the light wave visible, a digital holographic teaching apparatus, as a kind of comprehensive experimental platform, is developed by our teachers and students under the support of Daheng Science & Technology company. Digital holography (DH) can retrieve the quantitative amplitude and phase information of the object wavefront, which makes the wavefront display possible. In the teaching apparatus, the digital hologram is recorded by the off-axis lensless Fourier transform (LFT) digital holographic system, and the reconstruction of the hologram is achieved by the inverse Fourier Transform. The system is controlled by the Labview software. Except the quantitative amplitude and phase information, the spectrum of the hologram in the spatial-frequency domain etc. can also be visualized in the user interface of the apparatus. This can help students intuitively comprehend many optical content including phase, optical interference, diffraction, optical Fourier transform and diffraction propagation calculation et al., which has the characteristics of being open, flexible and systematic. Furthermore, the analytical and manipulative ability of students can be effectively advanced, and students can also generally understand the actual demand, work pattern and product sales of the company.
|
