In the streak tube laser imaging system, there are two conflicts: the first is between high spatial resolution and wide field of view (FOV). The second is between high temporal resolution and deep depth of field (DOF). In this paper, a new non-scanning streak tube laser imaging system is presented. A microlens array with three different apertures is used to non-uniformly collect data from the image plane so the conflict between high spatial resolution and wide FOV is relieved and the detectable range of system is also increased. A remapping fiber optics with special design is used to realign the image plane on the two photocathodes of streak tubes to realize the operation mode of the two streak tubes so the conflict between high temporal resolution and deep DOF is relieved. The mathematical model of the entire imaging system is established based on the range equation. The structure parameters of the receiving optical system are optimized in order to achieve the optimal utilization rate of light energy. In the third, three simulated contrast experiments are organized, and the experiment results demonstrate that the imaging system proposed in this paper possesses properties of higher spatial resolution, wider FOV, higher temporal resolution, deeper DOF, and larger detectable range.

Design and modeling of three-dimensional laser imaging system based on streak tube

Range accuracy analysis of streak tube imaging lidar systems

The utility model discloses an optical fiber bundle spectrometer comprising an optical fiber bundle, a dispersing element, and an array detector element; wherein an output end of the optical fiber bundle is arranged into a light slit, and is fixedly arranged on an incident light path of the dispersing element to directly act as an incident slit of the spectrometer, thus energy loss of a sampling light signal can be greatly reduced, sensitivity of an instrument can be greatly raised, and errors of the instrument, such as nonlinearity, dark noise, and stray light, can be also reduced, therefore, the optical fiber bundle spectrometer has a high measuring precision and a quick measuring speed. By utilizing the two-dimension array detector, ordered arrangements of optical fiber units at an input end and the output end of the optical fiber bundle, and parallel connections of a plurality of sub optical fiber bundle spectrometers, the optical fiber bundle spectrometer of the utility model can realize a two-dimension image spectral measurement and a multi-purpose spectral measurement, and has the advantages of no mechanical scanning or switching mechanism, quick measuring speed, high measuring precision, flexible configuration, wide application scope, etc.

Optical fiber bundle spectrometer

Experiments of ocean surface waves and underwater target detection imaging using a slit Streak Tube Imaging Lidar

Here we report on a modulated sub-nanosecond lidar-radar for underwater target detection. The modulated laser source is consisted of a 1064 nm master oscillator power amplifier (MOPA) and a frequency-doubling module, outputting pulse energy of 178.1 mJ at 1064 nm with 0.76 ns pulse duration and 87.6 mJ at 532 nm. By using a Fabry–Perot cavity containing a KTP crystal and two reflectors, the 532 nm laser pulse is modulated into the burst mode with a repetition rate of 500 MHz. A streak tube camera is used as the signal receiving apparatus. An underwater target detection experiment has been carried out. The results indicate that this lidar-radar could emit a stable and powerful modulated signal, which greatly increases the underwater detection range. The cooperation of the streak tube imaging and modulated laser source for underwater target detection experiments is the first attempt in this field. The clear 3-D and 4-D images of the target underwater across 20 m are obtained in the experiments and the spatial resolution of 9 mm can be achieved.

Lidar-radar for underwater target detection using a modulated sub-nanosecond Q-switched laser

The utility model discloses a spectrum color analyzer which comprises a lighting system, a photoelectric spectrograph and a signal collecting and processing system. Main technical characteristic is that: the lighting system adopts integrating sphere illumed by standard light source. Diffuse reflectance light generated by the integrating sphere illumes samples and is reflected by samples. Reflected light is transmitted to the photoelectric spectrograph through focusing battery of lens and is divided into a straight spectral line in a coupling way by holographic flat field concave grating, and then is received by a linear array CCD detector. The signal collecting and processing system stores, collects and calculates signals output by the linear array CCD detector according to built-in program, finally acquiring the samples color parameters which are displayed by a display screen. The utility model not only is characterized in miniaturization and intelligence but also has the advantages of high color measuring accuracy, high color measuring rate and excellent repeatability of wavelength measuring. The utility model has good prospect for application and popularization.

Spectrum colour analyter

Streak tube imaging lidar (STIL) is an active imaging system using a pulsed laser transmitter and a streak tube receiver to produce 3D range and intensity imagery. The STIL has recently attracted a great deal of interest and attention due to its advantages of wide azimuth field-of-view, high range and angle resolution, and high frame rate. This work investigates the signal-to-noise performance of STIL systems. A theoretical model for characterizing the signal-to-noise performance of the STIL system with an internal or external intensified streak tube receiver is presented, based on the linear cascaded systems theory of signal and noise propagation. The STIL system is decomposed into a series of cascaded imaging chains whose signal and noise transfer properties are described by the general (or the spatial-frequency dependent) noise factors (NFs). Expressions for the general NFs of the cascaded chains (or the main components) in the STIL system are derived. The work presented here is useful for the design and evaluation of STIL systems.

Signal-to-noise performance analysis of streak tube imaging lidar systems. I. Cascaded model.

In the preceding paper (referred to here as paper I), we presented a general signal-to-noise performance analysis of a streak tube imaging lidar (STIL) system within the framework of linear cascaded systems theory. A cascaded model is proposed for characterizing the signal-to-noise performance of a STIL system with an internal or external intensified streak tube receiver. The STIL system can be decomposed into a series of cascaded imaging chains whose signal and noise transfer properties are described by the general (or the spatial-frequency dependent) noise factors (NFs). Equations for the general NFs of the cascaded chains (or the main components) in the STIL system are derived. This work investigates the signal-to-noise performance of an external intensified STIL system. The implementation of the cascaded model for predicting and evaluating the signal-to-noise performance of the external intensified STIL system is described. Some factors that limit the signal-to-noise performance of the external intensified STIL system are analyzed and discussed.

Signal-to-noise performance analysis of streak tube imaging lidar systems. II. Theoretical analysis and discussion.

The invention discloses a near infrared weak pulse spectral radiance calibration device which belongs to the technical field of optical metrology. The device comprises a light source component which is used for grating spectrometer calibration, an optical fiber component with an array optical fiber bundle, a computer provided with a spectral radiance calibration data processing software package and a grating spectrometer with a flat field concave surface grating and a surface array EMCCD. The input end of the array optical fiber bundle is a single optical fiber, and the output end comprises n optical fibers in line arrangement. A pulse light beam emitted by a measured pulse light source passes through the optical fiber component and a slit, and is dispersed by the flat field concave surface grating. Dispersed lights are focused onto the photosensitive surface of the surface array EMCCD to form n rows of line spectrum. The computer collects n rows of line spectrum, acquires the spectral radiance value of the measured pulse light source changing with wavelength according to a spectral radiance calculation formula, and shows a single width or multi width spectral radiance curve on a computer screen. The device provided by the invention solves the problem of difficult calibration of the spectral radiance of a near infrared weak pulse light source, and has a broad application prospect.

Near infrared weak pulse spectral radiance calibration device

The invention discloses a transient ultraviolet multispectral radiometer, comprising a plug-pull type aiming lens, a guide rail component, a cassegrain imaging system, an ultraviolet spectrograph, a CCD driving circuit, a high-speed collection storage system and a computer which is provided with a spectrum measure data processing soft package. The cassegrain imaging system aims at a light source to be detected with the help of the aiming lens, adjusts self-focal distance and makes the light source to be detected for imaging clearly on the incidence slit of the ultraviolet spectrograph; the output optical signal of the ultraviolet spectrograph is converted to an electrical signal through the CCD driving circuit and is collected and stored by the high-speed system, and then is transmitted to the computer by a USB line. The spectrum measure data processing soft package calculates the spectrum power curve, the peak value wavelength, the corresponding power value of the light source to be detected according to relevant calculation means. The invention not only can detect the ultraviolet spectrum of the microsecond transient line light source and the transient side light source during single flashing time, but also can detect the ultraviolet spectrum of the steady state radiation light source including weak energy or the far radiation light source, and has good application prospect.

Baoning Wu

Papers

Spectrum colour analyter

Signal-to-noise performance analysis of streak tube imaging lidar systems. I. Cascaded model.

Signal-to-noise performance analysis of streak tube imaging lidar systems. II. Theoretical analysis and discussion.

Near infrared weak pulse spectral radiance calibration device

Transient ultraviolet multi-spectrum radiacmeter