Abstract: A Volume Bragg grating (VBG) is placed in the back of a collimating lens, the incident angle between exposure light beam and the Volume Bragg grating is equal to the Bragg angle of the Volume Bragg grating. A photodetector is placed in the ?1 grade transmission diffraction light path of the Volume Bragg grating which the exposure light beam is emitted to. The pinhole filter is moved back and forth along an optical axis and the reading of the photodetector is observed in real time. When the reading of the photodetector is maximum, fix the pinhole filter and keep the distance between the first pinhole filter and the first collimating lens a constant. The method for adjusting the self-collimation optical path is provided, using the Volume Bragg grating to detect the parallelism of self-collimation light and substituting for a traditional Moire pattern adjustment method.

Abstract: Disclosed is a baud rate tracking and compensation apparatus comprising: a clock generating component generating a clock; a sampling circuit sampling a reception signal according to the clock and thereby generating a sampled result, and the sampling circuit generating a transition notification signal when the sampled result indicates a transition of the reception signal; a clock counting circuit counting cycles of the clock between a first transition of the reception signal and a second transition of the reception signal according to the clock and the transition notification signal; a bit counting circuit counting bit(s) between the first transition and the second transition according to the clock and a bit cycle; and a calculation circuit dividing the number of the cycles by the number of the bit(s) to obtain a calculation value, and then updating the bit cycle according to the calculation value.

Abstract: A Volume Bragg grating (VBG) is placed in the back of a collimating lens, the incident angle between exposure light beam and the Volume Bragg grating is equal to the Bragg angle of the Volume Bragg grating. A photodetector is placed in the ?1 grade transmission diffraction light path of the Volume Bragg grating which the exposure light beam is emitted to. The pinhole filter is moved back and forth along an optical axis and the reading of the photodetector is observed in real time. When the reading of the photodetector is maximum, fix the pinhole filter and keep the distance between the first pinhole filter and the first collimating lens a constant. The method for adjusting the self-collimation optical path is provided, using the Volume Bragg grating to detect the parallelism of self-collimation light and substituting for a traditional Moire pattern adjustment method.

Abstract: Disclosed is a baud rate tracking and compensation apparatus comprising: a clock generating component generating a clock; a sampling circuit sampling a reception signal according to the clock and thereby generating a sampled result, and the sampling circuit generating a transition notification signal when the sampled result indicates a transition of the reception signal; a clock counting circuit counting cycles of the clock between a first transition of the reception signal and a second transition of the reception signal according to the clock and the transition notification signal; a bit counting circuit counting bit(s) between the first transition and the second transition according to the clock and a bit cycle; and a calculation circuit dividing the number of the cycles by the number of the bit(s) to obtain a calculation value, and then updating the bit cycle according to the calculation value.

Abstract: This invention discloses a method for fabricating a holographic grating with low diffractive wave aberrations on a substrate with aberrations. Forming a interference recording field from two coherent beams, where one is a parallel beam and the other is a beam whose wave-front can be controlled, recording the holographic field on the substrate with aberrations, fabricating the holographic grating with low diffractive wave aberrations, setting a deformable minor into one of the coherent recording beams, and controlling the shape of said deformable minor so as to obtain a compensated interference recording field. Expose the recoding plate under the holographic interference recording field which has been adjusted by the deformable minor to record the grating. After developing, the fabrication of holographic grating with low diffractive wave aberration is finished.