Camera Head Unit Research Articles

Europa's Influence on the Jovian Energetic Electron Environment as Observed by Juno's Micro Advanced Stellar Compass

AbstractThe micro Advanced Stellar Compass is an attitude reference for the MAG investigation onboard Juno. The μASC camera head unit images the star field with a CCD that is also sensitive to particles with enough energy to pass through the camera shielding: >15 MeV electrons and >80 MeV protons. This provides the capability to monitor fluxes of high‐energy particles in Jupiter’s magnetosphere. A survey of energetic electron fluxes sampled during the first 47 Juno orbits reveals instances of variations observed when Juno is traversing the M‐shell of the Galilean moons. Juno's traversal of the Europa M‐shell often results in distinctly particle signatures. We present the μASC observations of increased electron flux during the crossing of Europa’s plasma wake, and depletion of energetic electron flux on the upstream side. The upstream/downstream differences indicate that the wake environment of Europa drives strong pitch angle scattering on relativistic electrons.

Energetic electron lensing caused by Ganymede's magnetic field

The micro Advanced Stellar Compass (μASC) continuously monitors high energy particle fluxes in Jupiter's magnetosphere while providing attitude reference for the Juno Magnetic Field investigation. The μASC camera head unit (CHU) serves as a energetic particle sensor monitoring the radiation environment at Jupiter by sensing electrons greater than 15 ​MeV that pass through the CHU shielding. A comparison of the energetic electron population sampled during many orbits reveals events observed when Juno is traversing Ganymede's M-shell. We present observations of energetic electron depletions related to the interaction with Ganymede's magnetic field. The magnitude and extent of these depletions is associated with Juno's proximity to the magnetic field line passing through Ganymede. Analysis of the observations reveal that the charged particle depletion likely arises from electron scattering in Ganymede's magnetic field, observed within ∼13° phase angle from the moon, beyond which the flux tubes refill due to diffusion.

Initial Experience of 4K Three-Dimensional Digital Microscope for Lymphaticovenular Anastomosis.

A digital microscope projecting the operative field onto a three-dimensional monitor has been developed and allows surgeons to perform “three-dimensional monitor–assisted microsurgery,” which is usually associated with distressful posture. A few articles in the neurosurgery field mentioned that the usability of digital microscopes was comparable to that of conventional optical microscopes.1 In the plastic surgery field, Ichikawa et al. and Piatkowski et al. reported the experience of the microvascular anastomosis with using the Vitom3D (Carl Storz, Tuttlingen, Germany),2,3 and Ahmed et al. also concluded that the usability of the ORBEYE (Olympus Corp., Tokyo, Japan) was not inferior to the optical microscope for microsurgery.4 However, there was a limitation for the usability in supermicrosurgery, defined as anastomosis of small vessels ranging from 0.3 to 0.8 mm because of the resolution under the large manipulation of the digital microscope. To support this, any articles regarding supermicrosurgery using digital microscopes have not been published. Herein, we report the initial experience of the lymphaticovenular anastomosis using a new type of digital microscope, the Hawk Sight (Mitaka, Tokyo, Japan). The lymphaticovenular anastomosis was approved by the Juntendo University Hospital Institutional Review Board in February of 2020 (approval number 19-101). In this study, lymphaticovenular anastomosis using the Hawk Sight was attempted in seven cases of cancer-related extremity lymphedema (upper limbs, n = 5; lower limbs, n = 2) and 13 anastomoses in total by two microsurgeons. The Hawk Sight was used during the dissection of lymphatic vessels and venules and microvascular anastomosis (Fig. 1). [See Video 1 (online), which demonstrates an overview of the lymphaticovenular anastomosis procedures with three-dimensional monitor–assisted microsurgery using the Hawk Sight. In this video, the principal surgeon is performing all procedures, using the 4K three-dimensional monitor.] All anastomoses between lymphatic vessels and venules were conducted in an end-to-end fashion. The average luminal diameter in the lymphatic vessel was 0.47 mm and the average anastomosis time was 31.5 minutes. The patency was confirmed by the lymph fluid flow from the lymphatic vessel to the vein by kneading and the indocyanine green angiography built into the Hawk Sight intraoperatively. (See Figure, Supplemental Digital Content 1, which shows an intraoperative view of indocyanine green angiography to check the patency of the anastomosis. The high-tech clarity enables surgeons to evaluate the patency with ease, https://links.lww.com/PRS/F393. See Video 2 (online), which demonstrates the monitor view of the anastomosis, the patency check, and the mode transition in indocyanine green angiography. The green color reflects the high density of the indocyanine green and helps assessment of the patency.] {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 1.","caption":"This video demonstrates an overview of the lymphaticovenular anastomosis procedures with three-dimensional monitor–assisted microsurgery using the Hawk Sight. In this video, the principal surgeon is performing all procedures, using the 4K three-dimensional monitor.","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_1l9advlg"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} {"href":"Single Video Player","role":"media-player-id","content-type":"play-in-place","position":"float","orientation":"portrait","label":"Video 2.","caption":"This video demonstrates the monitor view of the anastomosis, the patency check, and the mode transition in indocyanine green angiography. The green color reflects the high density of the indocyanine green and helps assessment of the patency.","object-id":[{"pub-id-type":"doi","id":""},{"pub-id-type":"other","content-type":"media-stream-id","id":"1_gjkele2d"},{"pub-id-type":"other","content-type":"media-source","id":"Kaltura"}]} Fig. 1.: Overview of the lymphaticovenular anastomosis under the latest digital microscope, Hawk Sight. The focal length is so short that the camera head unit does not interfere with the principal operator’s straight view and the assistant’s view. The maximum manipulation is 110× under the minimum focal length (20 cm).To date, several digital microscopes are available in the operative field, and each digital microscope has the original features for outlook, focal length, zoom function, optics, and cost. When considering supermicrosurgery using digital microscopes, the important aspect is high resolution on the monitor under the maximum manipulation without disturbance of the straight view. The Hawk Sight has an incredibly wide and short focal length (200 to 1000 mm), coherent optical zoom system (8×), and 4K three-dimensional optics, and those technologies broke the limitations and allow microsurgeons to perform supermicrosurgery with “heads-up” style, which is better for surgeon ergonomics. In addition, its resolution in indocyanine green mode is so clear that it enables projection of the duct brightly and sharply and evaluation of the patency precisely. Meanwhile, the procedures’ time for dissection and anastomosis were prolonged compared to the conventional method using an optical microscope. In our opinion, because the main reason was the nearly short focal depth under the maximum manipulation, even surgeons familiar with the lymphaticovenular anastomosis procedure might feel this is troublesome when they start lymphaticovenular anastomosis by three-dimensional monitor–assisted microsurgery at the beginning. However, we consider this issue can be overcome with experience with this method. In conclusion, there seems to be room yet for improvement of digital microscopes, but the paradigm shift from optical microscopes to digital microscopes is coming to the field not only of microsurgery but also of supermicrosurgery, including lymphaticovenular anastomosis. DISCLOSURE The authors have no financial interest to declare in relation to the content of this article.

Thermoelastic Response of the Juno Spacecraft's Solar Array/Magnetometer Boom and Its Applicability to Improved Magnetic Field Investigation.

Juno was inserted into a polar orbit about Jupiter on 4 July 2016. Juno's magnetic field investigation acquires vector measurements of the Jovian magnetic field using a pair of a triaxial Fluxgate Magnetometers (FGMs) colocated with four attitude‐sensing star cameras on an optical bench. The optical bench is placed on a boom at the outer extremity of one of Juno's three solar arrays. The Magnetic Field investigation (MAG) uses measurements of the optical bench inertial attitude provided by the micro‐Advanced Stellar Compass (μASC) to render accurate vector measurements of the planetary magnetic field. During periJoves, orientation of the MAG Optical Benches (MOB) is determined using the spacecraft (SC) attitude combined with transformations between SC and MOB coordinate frames. Substantial prelaunch effort was expended to maximize the thermomechanical stability of the Juno solar arrays and MAG boom. Nevertheless, the Juno flight experience demonstrates that the transformation between SC and MAG reference frames varies significantly in response to spacecraft thermal excursions associated with large attitude maneuvers and proximate encounters with Jupiter. This response is monitored by comparing attitudes provided by the MAG investigation's four Camera Head Units (CHUs) with those provided by the Stellar Reference Unit (SRU). These systematic variations in relative orientation are thought to be caused by the thermoelastic flexure of the Juno solar array in response to temperature excursions associated with maneuvers and heating during close passages of Jupiter. In this paper, we investigate these thermal effects and propose a model for compensation of the MAG boom flexure.

Rigid chip-on-the-tip endoscope for rhinosurgery and diagnosis

Abstract BACKGROUND. The rigid endoscope developed by Karl Storz in 1961 led to a great advance in diagnosis and surgery and nowadays it is the gold standard in routine ENT practice. In addition, the development of video cameras has enhanced the surgical abilities as well as teaching opportunities in endoscopic sinus surgery. OBJECTIVE. We developed a new prototype endoscope using the “chip-on-the-tip” technology. The aim of our non-clinical study was to observe and discuss the experimental data collected from laboratory tests on plastic models. MATERIAL AND METHODS. The prototype rigid chip-on-the-tip endoscope has two parts - inner and outer. The inner part includes the chip-on-the-tip camera, light source and the cable. The outer part is a metal tube ending with a 0-degree lens. We performed laboratory tests of the rigid chip-on-the-tip endoscope for rhinosurgery and diagnosis. RESULTS. We have observed technical parameters of the rigid chip-on-the-tip in order to compare them to conventional endoscopes connected with camera head units that are standard equipment for rhinosurgery and diagnosis. CONCLUSION. Its advantages compared to the conventional Hopkins endoscope, connected to a standard camera head, are the smaller size, weight and the necessity of only one cable instead of two, allowing easy handling.

Characterization and compensation of thermo-elastic instability of SWARM optical bench on micro Advanced Stellar Compass attitude observations

Launched into orbit on November 22, 2013, the Swarm constellation of three satellites precisely measures magnetic signal of the Earth. To ensure the high accuracy of magnetic observation by vector magnetometer (VFM), its inertial attitude is precisely determined by µASC (micro Advanced Stellar Compass). Each of the three Swarm satellites is equipped with three µASC Camera Head Units (CHU) mounted on a common optical bench (OB), which has a purpose of transference of the attitude from the star trackers to the magnetometer measurements. Although substantial pre-launch analyses were made to maximize thermal and mechanical stability of the OB, significant signal with thermal signature is discovered when comparing relative attitude between the three CHU's (Inter Boresight Angle, IBA). These misalignments between CHU's, and consequently geomagnetic reference frame, are found to be correlated with the period of angle between Swarm orbital plane and the Sun (ca. 267 days), which suggests sensitivity of optical bench system on temperature variation.In this paper, we investigate the propagation of thermal effects into the µASC attitude observations and demonstrate how thermally induced attitude variation can be predicted and corrected in the Swarm data processing. The results after applying thermal corrections show decrease in IBA RMS from 6.41 to 2.58″. The model significantly improves attitude determination which, after correction, meets the requirements of Swarm satellite mission. This study demonstrates the importance of the OB pre-launch analysis to ensure minimum thermal gradient on satellite optical system and therefore maximum attitude accuracy.

Attitude disturbance correction for binocular vision cameras in rendezvous and docking

Vision-based relative position and attitude measurement methods are widely used in rendezvous and docking (RVD). For example, a structured light vision-based sensor (the advanced video guidance sensor) was included as one of the primary proximity navigation sensors in the Orbital Express mission [1]. A monocular vision-based sensor (hand–eye camera mounted on the end effector and monitor camera mounted on the first joint of the robot arm) is used in Engineering Test Satellite No. 7 to locate cooperative targets [2]. In the Front-end Robotics Enabling Near-term Demonstration, a binocular vision-based sensor (camera head unit LIDAR) is used to locate noncooperative targets [3].

MicroASC instrument onboard Juno spacecraft utilizing inertially controlled imaging

This contribution describes the post-processing of the raw image data acquired by the microASC instrument during the Earth-fly-by of the Juno spacecraft. The images show a unique view of the Earth and Moon system as seen from afar. The procedure utilizes attitude measurements and inter-calibration of the Camera Head Units of the microASC system to trigger the image capturing. The triggering is synchronized with the inertial attitude and rotational phase of the sensor acquiring the images. This is essentially works as inertially controlled imaging facilitating image acquisition from unexplored perspectives of moons, asteroids, icy rocks and planetary rings.

Autonomous vision-based detection of non-stellar objects flying in formation with camera point of view

The μ-advanced stellar compass (μASC) is a camera system which autonomously can provide attitude information based on the visible stars. An extended functionality of the μASC, called the vision-based sensor (VBS), enables the camera system to render rendezvous and docking navigation information for a formation flying spacecraft. The VBS system facilitates different operation modes, enabling i.e. inertial line-of-sight (LoS) solutions for any spacecraft reflecting more light than an Mv7 star. This paper will focus on the LoS solutions of the VBS system, with a thorough analysis of inflight performance and future mission aspects. The captured data used for the analysis presented in this paper, includes centroids from the VBS camera head unit (CHU) dedicated for inertial LoS operation and from the two standard startracker CHUs. By combining the data from these three CHUs, a total of 300 hours of operation distributed over the entire year is included in the thorough data analysis and performance characterisation.

CCD micro-miniature color camera

A microminiature color camera system with an extremely small camera head utilizing a CCD (computer-controlled display) image sensor is described. The camera system consists of a camera head unit with a camera holder, a camera control unit, and an AC power supply unit. The camera head is connected to the camera control unit by a 4 mm diameter, 2 m long cable. The design used separates the camera head from the control unit, so that it can meet a variety of customer needs or special purposes. Since the output signal from the camera control unit is a standard NTSC signal, it can be easily connected to a standard TV monitor or to an independent video cassette recorder. The camera head (17.5 mm in diameter and 53 mm in length) incorporates a small, wide-angle 7.5 mm focus lens, a 200000 picture element CCD image sensor with color filter array and compact electronic circuits. The design, specifications and applications of the system are discussed.