Video encryption/compression using compressive coded rotating mirror camera

Compressive coded rotating mirror (CCRM) camera is a novel high-speed imaging system that operates under amplitude optical encoding and frame sweeping modalities in a passive imaging mode that is capable of reconstructing 1400 frames from a single shot image acquisition and achieves the highest compression ratio of 368 compared to the other compressive sensing (CS) based single-shot imaging modalities. The integrated optical encoding and compression adds a strong layer of encryption on the observed data and facilitates the integration of the CCRM camera with the imaging applications that require highly efficient data encryption and compression due to capturing highly sensitive data or limited transmission and storage capacities. CCRM uses amplitude encoding that significantly extends the key space where the probability of having the exact encoder pattern is estimated as $$P\left( A\right) \ =\ 1/{10}^{122,500}$$ P A = 1 / 10 122 , 500 , hence drastically reducing the possibility of data recovery in a brute force manner. Data reconstruction is achieved under CS based algorithms where the obtained amplitude-based pattern from optical encoder operates as the key in the recovery process. Reconstruction on the experimental as well as the synthetic data at various compression ratios demonstrate that the estimated key with less than 95$$\%$$ % matching elements were unable to recover the data where the achieved averaged structural similarity (SSIM) of 0.25 before 95$$\%$$ % encoder similarity and 0.85 SSIM at 100$$\%$$ % encoder similarity demonstrates the high-sensitivity of the proposed optical encryption technique.

A Self-Calibration Stitching Method for Pitch Deviation Evaluation of a Long-Range Linear Scale by Using a Fizeau Interferometer

An interferometric self-calibration method for the evaluation of the pitch deviation of scale grating has been extended to evaluate the pitch deviation of the long-range type linear scale by utilizing the stitching interferometry technique. Following the previous work, in which the interferometric self-calibration method was proposed to assess the pitch deviation of the scale grating by combing the first-order diffracted beams from the grating, a stitching calibration method is proposed to enlarge the measurement range. Theoretical analysis is performed to realize the X-directional pitch deviation calibration of the long-range linear scale while reducing the second-order accumulation effect by canceling the influence of the reference flat error in the sub-apertures’ measurements. In this paper, the stitching interferometry theory is briefly reviewed, and theoretical equations of the X-directional pitch deviation stitching are derived for evaluation of the pitch deviation of the long-range linear scale. Followed by the simulation verification, some experiments with a linear scale of 105 mm length from a commercial interferential scanning-type optical encoder are conducted to verify the feasibility of the self-calibration stitching method for the calibration of the X-directional pitch deviation of the linear scale over its whole area.

Investigation On Ultra-Compact, High Contrast Ratio 2d-Photonic Crystal Based All Optical 4 x 2 Encoder

Optical encoder is playing an essential starring role in optical communication and computing applications. This paper presents a new structure for 4 x 2 optical encoder based on Two Dimensional Photonic Crystals (2DPC). The proposed structure consists of silicon rods in background of air using hexagonal lattice. The proposed structure is composed of four input waveguides and two outputs. The band structure is examined by Plane Wave Expansion (PWE) method and the performance parameters of the 4x2 encoder, namely, normalized output power, footprint, contrast ratio, response time and bit rate are analyzed using Finite Difference Time Domain (FDTD) method. The proposed encoder is operated at 1550nm. The low response time, and small footprint have shown that the encoder is exceptionally suitable for high performance optical networks and photonic computational integrated devices.

High data rate and ultra-compact optical encoder based on 2D linear photonic crystal ring resonator

In the present work, a high-speed optical encoder is proposed based on two-dimensional photonic crystal ring resonator (2D-PCRR) using coupled mode theory and resonance effect. Square shaped ring resonator, couplings rods and several waveguides have been utilized in the proposed structure. Silicon rods in air structure has been designed with rod radius of 0.1a and lattice constant 0.540 nm. The photonic band gap is being calculated using plane wave expansion method and finite-difference-time-domain method to analyze the performance characteristics of optical encoder like: transmission spectra, electric field view, contrast ratio, delay time, response time etc. The operating wavelength of structure is 1550 nm, to perform encoder operation where only one input port is activated at a time while other input ports are inactivated and accordingly equivalent binary encoded signal is produced at output ports. The proposed encoder is designed with fast response time 222.76 fs, high data rate of 4.48 Tbps and ultra-compact size of 140.84µm2. Hence the proposed device is suitable for high-speed optical computation, photonic integrated devices and high speed optical integrated circuits.