Scaling to a higher-power green laser with good beam quality is a challenge for meeting the requirements of different industrial applications. An acousto-optic Q-switched TEM00 mode Nd:YLF laser using the master oscillator power amplifier (MOPA) technology is presented and demonstrated. Output power of 17.2 W and TEM00 mode laser of 527 nm at 1.5 kHz with a pulse energy of 11.5 mJ is achieved. The output green laser had a Gaussian spatial profile with beam quality factors of Mx2=1.07 and My2=1.15. Z-type end-pumping structures are used for the MOPA system to ensure laser power stability. The green laser power fluctuation is <0.3 % based on 4 h measurement data.
The technology of interferometric imaging spectrometer can detect spatial information and spectral information of targets simultaneously. It has been the research hotpot because of its advantages of high throughput, high spectral resolution, high spatial resolution and so on. In order to obtain the spectral images of scene at different distance, a system of interferometric imaging spectrometer is presented, which consists of two imaging lens, a collimating lens, a Sagnac transverse shearing splitter and a detector. Based on the analysis of the optical paths and structure of spectrometer, system parameters of interferometric imaging spectrometer were researched, especially the ones of the transverse shearing splitter, incident plane width, mirror offset, optical parallelism error, and the clear aperture of the imaging lens and collimating lens . Optimal system parameters were given by discussing the relationship of parameters including transverse shearing splitter, detection distance, imaging lens, collimating lens and detector. Experimental prototype is set up to verify the impact of the error of system parameters on the imaging properties.
The Fourier transform spectrometer without slit has the advantages of high radiation throughput and high spatial resolution. It can be used for detecting more details of the spectral and spatial information. We present the initial structure of the collimator and objective based on the analysis of the principle of the Fourier transform spectrometer. Then the collimator and objective are optimized by Zemax. The MTF of the cut-off frequency is great than 0.7. The tunable lateral shearing splitter is used as the interferometer, which makes the system more compact compared with the system using Sagnac lateral shearing splitter. The method to calculate the geometric dimension of the splitter is presented. Then the complete Fourier transform spectrometer is designed. The MTF of the cut-off frequency is great than 0.6. And the largest RMS of the spot is less than 6μm.
Fourier transform spectrometer without input slit is an emerging technology for spectral imaging. It has the advantages
of high spatial resolution and high radiation throughput compared to the similar device with input slit. A near-infrared
(NIR) Fourier transform spectrometer using Sagnac interferometer is presented and discussed in this paper. This system
is composed of a Sagnac interferometer used as a lateral shearing splitter, an objective and a NIR camera. The principle
of the system is presented including the discuss of its main characteristics and the optical layout of the Sagnac
interferometer. Then the main technical features are discussed, such as the sample of the optical path difference (OPD).
A experimental device is set up and presented that is used for two proven experiments. Some spectral images are
reconstructed from 1050nm to 1720nm and proves the feasibility of the proposed system for NIR spectral imaging.
The Stokes imaging polarimeter using a retarder and a polarizer is a direct and conventional method to detect the full Stokes vector of the scene. This method has been widely used for different imaging architectures, such as division of time and division of aperture. System calibration is necessary in polarimetric imagery. The polarization optical elements angular deviation belongs to adjustment error and should be calibration when the device is set up. In this paper we propose a novel method to calibration the angular deviation using Fourier series analysis. A linear polarization state generator including a light source and a linear polarizer is installed before the imaging polarimeter. The polarizer rotates 360-degree uniform and the signal intensity of the input light is recorded by the imaging polarimeter. The angle of the fast axis of the quarter-waveplate respect to the pass axis of the polarizer can be calculated from the obtained data by use of Fourier series analysis. The mathematic model of the presented method is established and proved by mathematical simulation.
The technology of image plane interferometric imaging spectrometer has been the research hotpot because of its high throughput, which brings the system a high Signal to Noise Ratio (SNR) and higher spectral resolution compared to other kinds of imaging spectrometer. In order to obtain the spectral images of scene at different distance, a system of image plane interferometric imaging spectrometer based on re-imaging is presented, which consists of a front-end objective lens, a collimator, a Sagnac lateral shearing interferometer, a back-end imaging lens and a detector. A separated front-end objective lens with zoom lens or fixed focus lens is adopted to image the scene on the first imaging plane. The light from the points in the first imaging plane is then collimated to parallel light by the collimator. Then the parallel light is sheared into two beams of coherent light by the Sagnac lateral shearing interferometer. The imaging lens converge the two beams on the detector. Intensity of the converged point is detected by the detector. The imaging system and resolution of spectrum are analyzed. Besides, two push broom modes are discussed. Experimental device is set up to detect the targets of near field indoor and far field outdoor. Twenty-six reconstructed spectral images are obtained from 460nm to 620nm. The experimental results show that the proposed imaging method is effectively applied in hyperspectral imaging of targets at different distances.
Full-Stokes imaging polarimetry has been a research hotspot in the past ten years because it can provide us the
full-Stokes parameters, from which we can reconstruct the complete polarization information. In this paper we describe a
direct method to obtain the full-Stokes parameters. A polarization modulator, composed of a retarder and a polarizer, is
installed before an imaging system. Four different angle combinations of the retarder and polarizer are used to create four
different polarization states to calculate the Stokes parameters. The principle of the method is outlined first. Then we
present different architectures of the system with their advantages and disadvantages including a novel structure using
aperture division with micro-optics element. Besides, the method can be incorporated into the Fourier transform
spectrometer to obtain the spectropolarimetric information.
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