An x-ray microscope is a useful tool in medicine and biology. The performance of an x-ray microscope critically depends on its x-ray optics. In this paper, a Wolter type-I x-ray mirror is considered for biological applications. It was fabricated using an epoxy replication method. Fabrication tolerances (figure error and surface roughness) of the soft x-ray mirror were examined. A master mandrel was prepared using single-point diamond turning and polishing, and a mirror with axial symmetry was successfully manufactured by coating of a parting agent, epoxy molding, and separation steps. The replicated mirror showed 1.4-nm rms surface roughness and 160-nm peak-to-valley (and 34.3-nm rms) figure error. Several mirrors were manufactured from only one master mandrel.
The micro-CT system has been developed for small animal imaging. The system is mainly composed of CCD detector coupled with CsI (Tl) phosphor, X-ray source with micro focal spot, linearly moving couch, and rotation gantry. This system was developed as a gantry rotation type and designed to get CT images of small living animals. In this paper, the requirements of main parts of the system to acquire micro spatial resolution are described. The characteristics of the system, such as field of view, geometries of main components, gantry movement, and X-ray analysis are mainly considered. Resolution of the CT system was evaluated under variable conditions. Typically, the spatial resolution of the CT system was obtained about 37 micron at 10% of MTF curve.
This paper presents a method of a nano-positioning control for the high precision focusing of a doubled ellipsoidal condenser reflective mirror using 5-axis manipulator. We have developed the compact vertical type of soft X-ray microscopy system with 50nm resolution for biomedical application. This microscopy system is composed of a laser plasma x-ray source, doubled ellipsoidal condenser reflective optics, diffractive zone plate optics and MCP coupled with CCD to record an x-ray image. The X-ray source was focused on a sample by a doubled ellipsoidal condenser reflective mirror. X-ray source focusing will increase the photon density in the object plane and is very important to approach high resolution imaging. Required degree of freedom (DOF) of optics aligner in X-ray microscope is dependent on the kind of optics, but generally 5-DOF is needed. We used 5-axis manipulator that consists of three linear motions (X, Y and Z) and two tilting motions (θx, θy). A linear translation stage is adopted a kind of DC motor with a linear resolution 50nm and travel range of 5mm. The mechanism was controlled with PID controller augmented with closed feedback loop for precision control. A two axis tilt stage is employed a design resolution of 0.23μrad and tilt range of ±7deg. We have designed 5-axis manipulator for the precision position control of condenser mirror optics and have developed to control algorithm by inverse kinematics. The performance of the proposed 5-DOF manipulator is evaluated by using a laser interferometer system with two plane mirror reflectors. The experimental results are depicted in this paper.
We demonstrate compact transmission soft X-ray microscope system with 50 nm spatial resolution for the life and physical science. This x-ray microscope operates at photon energy from 284 eV to 543 eV, so called 'water window' region (2.3~4.4nm), where natural contrast between carbon (protein) and oxygen(water) allows imaging of unstained biological material in their natural, hydrated environment. The compact transmission soft x-ray microscope is based on a laser plasma x-ray source, tandem ellipsoidal condenser reflective optics, diffractive zone plate optics and x-ray sensitive charge-coupled device (CCD) to record an x-ray image. The source is a liquid-jet target laser plasma source, which is practically debris free and suitable for high average power operation. The flux, brightness and bandwidth of this source has been simulated and optimized for X-ray microscopy for biology application. A tandem ellipsoidal reflective mirror operates as condenser and illuminates the sample. The high resolution imaging is currently performed with a ~12% efficient nickel zone plate with an outmost zone width of 35nm. In conclusion, we suggested a possibility of the compact soft x-ray microscopy system with 50 nm spatial resolution as a suitable tool for the wide range of studies such as biological imaging, environmental samples, and nanostructure analysis.
A compact soft X-ray microscope system has been developed for biological applications with nano-scale resolution. Soft X-ray used to the system is emitted from a solid target by using Nd-YAG pulsed laser. Boron nitride (BN) is used as the target materials in the system. The optics of the microscope system is adopted with wolter type-I mirrors, which is consisted of a condenser mirror with demagnification of 1/4× and an object mirror with magnification of 32×. The surface roughness of the machined wolter mirrors is about 0.8 nm (Ra) after polishing. In this paper, the X-ray characteristics, i.e., spectrum and intensity emitted from laser plasma-based x-ray source was measured. Imaging test using the system was performed with gold 2000 mesh. The spatial resolution of the soft x-ray microscope system was obtained about 900 nm.