Mikio Takabayashi

Development of long range, real-time, and high resolution 3D imaging ladar

In the previous study, we have introduced the concept of the real-time 3D imaging LADAR (LAser Detection And Ranging) using linear array receiver. In this paper, we demonstrate a long range, high resolution, and high speed 3D imaging using the developed system. The system consists of in-house-made key components. The linear array receiver consists of the previously reported APD array and the ROIC array assembled in one package. We newly developed the transmitting optics using pupil divide method which realizes a uniform illumination on a target. By combining these devices with the one dimensional fast scanner, we realized a 256 × 256 pixels range imaging with a on-line frame rate of more than 10 Hz at a distance of more than 1 km.

An analysis of multimode conical horn antennas with flare-angle changes by using generalized telegraphist's equation

A multimode conical horn antenna can realize a rotationally symmetric radiation pattern with a low cross polarization level by exciting a dominant mode and higher-order modes with appropriate composition ratios. One of the mechanisms to generate the higher-order modes is a flare type in which the flare angle of the horn is varied. This structure is simple and can be made only with a conductor. In this paper, an analysis of a flared multimode conical horn antenna using a generalized telegraphists equation is described. In the present method, many higher-order modes are considered in the telegraphists equation; the results are confirmed to agree well with the measured results and thus the validity of the method is proven. A design method based on the presented analysis procedure is also described. It is confirmed that sufficient accuracy can be obtained in this design.

Pulsed 3D laser sensor with scanless receiver

3D laser sensor is a real-time remote sensor which offers 3D images of scenes. In this paper, we demonstrate a new concept of the pulsed 3D laser sensor with 2D scanning of a transmitting beam and a scan-less receiver. The system achieves the fast and long-range 3D imaging with a relatively simple system configuration. We newly developed a highaspect APD array, a receiver IC, and a range and intensity detector. By combining these devices, we realized a 160 × 120 pixels range imaging with an on-line frame rate of 8 Hz at a distance of about 50 m.

Demonstration on range imaging of 256×256 pixels and 30 frames per second using short wavelength infrared pulsed time-of-flight laser sensor with linear array receiver

Abstract. We demonstrated the range imaging with high resolution of 256×256  pixels and high frame rate of 30 frames per second (fps) using a short wavelength infrared pulsed time-of-flight laser sensor, which is suitable for long range imaging. We additionally demonstrated the long range imaging of more than 1 km and wide field of view imaging of 12  deg× 4  deg, 768×256  pixels, and 10 fps. For these demonstrations, we developed the linear array devices of the aluminum indium arsenide avalanche photodiode array and silicon germanium bipolar complementary metal oxide semiconductor read-out integrated circuit array. We also deployed the flattop beam illumination optics with the beam division and recombination method and realized efficient line shape illumination.

Performance improvement of real-time 3D imaging ladar based on a modified array receiver

In the previous study, we have demonstrated the first development result of the 3D imaging LADAR (LAser Detection And Ranging) which can obtain the 3D data using linear array receiver. The system consists of in-house-made key components. The linear array receiver consists of the previously reported APD (Avalanche Photo Diode) array, the ROIC (Read Out Integrated Circuit) array assembled in one package, and the transmitting optics using pupil divide method which realizes a uniform illumination on a target. In this paper, we report the advanced 3D imaging LADAR with improved ROIC. The ROIC has the function to set the optimum threshold for pulse peak detection in each element and switch the measurement range width on a case by case basis. Moreover, the response of MUX in ROIC is improved. Installing this ROIC, we realized 256× 256 pixels range imaging with an on-line frame rate of more than 30 Hz. Then, we tried online object detection with the obtained 3D image using a simple detection algorithm. We demonstrated system has the potential to detect the object even in the scene with some clutters.