對於一個簡單的體積全像儲存相位解碼方法，並且能夠精確地讀取出資訊是必要的。此邊我們提出一個模組叫做雙頻光柵剪切干涉儀(Doubl-frequency grating based shearing interferometry簡稱DFGSI)。此模組是利用全像片，上記錄了兩種不同空間頻率的光柵，稱為雙頻光柵(Double-frequency grating，簡稱 DFG)。並配合四步相移技術來做全像儲存的四階相位訊號解碼，模擬得證用此模組可以消除碟片震動所造成的相位錯誤雜訊影響，進而讀出準確的資訊，達到誤碼率小於1%。實驗部分可以應證輸入一個完美訊號，此模組的剪切位移量可以達到符合預期的效果且能有效地消除雜訊得到較好的誤碼率。;A simple method to decode the stored phase signal of volume holographic data storage precisely is highly demanded. We promote a module called double-frequency-grating based shearing interferometry (DFGSI). Double-frequency grating is the Holographic film which is recorded by two different space frequency grating . We combine with the phase shift interferometry to decode the signal modulated by four step phase only. The simulation prove this module can remove the noise caused by shifting the disc laterally. Then, it can decode the signal correctly, and the bit error rate is less than 1%. The experiment prove that we input the perfect signal to this module. Then the displacement of shearing interferometer can achieve the effect we expected. In addition, it can remove the noise efficiently to have the better bit error rate.