In this proceedings, we present a 3DoF (one linear, two angular) optical probe for measuring freeform optics in conjunction with an optical coordinate measuring machine (OCMM). This probe uses homodyne interferometry in a Michelson configuration and position sensing detection to simultaneously measure displacement, tip, and tilt. The goal of this work is to investigate point-to-point methods for measuring freeform optics and establish a probing methodology that can perform self-alignment with respect to the local optical surface. We present the design and preliminary benchtop validation of the probe's performance. Benchtop validation shows successful measurements with 5 nm linear and 20 μrad angular noise levels, with a 15 μm spot size. A CMOS sensor is used for visual confirmation of proper focus on measurement surface to minimize initial defocus error. A PSD detects linear horizontal and vertical displacement of the reflected beam from the measurement surface using autocollimation. In-phase and quadrature signals are measured by two photodetectors and post-processed to obtain displacement information. Periodic error caused by polarization effects and beam mixing is compensated by FPGA-based signal processing.
Conformal optical dome can induce the drag of the missile. The conformal dome test is an important way to make the dome perfect for imaging. This paper shows a interference test of elliptical conformal dome's inside surface. First, the test system is designed by zero position method. The test system is composed by two parts: the focal lens and the spherical mirror. The interferometer used is operating in 632.8nm. The ideal test system's resolution is 0.0065waves in PV(peak to valley) value and 0.004 waves in RMS(root mean square) value. The next step is tolerance analysis. According to the optical and mechanical manufacture level, the tolerance analysis is done by optical software ZEMAX. The results are 1.219 waves in PV value and 0.249 in RMS value. The working wavelength is 4.2μm for conformal dome. After calculation, the PV value is 0.179 waves and the RMS value is 0.0366 waves. Finally, the bolster is designed, and for the key structure the topology optimizing is simulated
In the modern war, UAV(unmanned aircraft system) plays a more and more important role in the army.
UAVs always carry electrical-optical reconnaissance systems. These systems are used to accomplish
the missions of observing and reconnaissance the battlefield. For traditional UAV, the shape of the pod
on UAV is sphericity. In addition, the pod of UAV not only has the job of observing and reconnaissance
the battlefield, but its shape also has impact on the UAV's drag when it flies in the air. In this paper,
two different kinds of pod models are set up, one is the traditional sphericity model, the other is a new
model. Unstructured grid is used on the flow field. Using CFD(computational fluid dynamic) method,
the results of the drags of the different kinds of pod are got. The drag's relationship between the pod
and the UAV is obtained by comparing the results of simulations. After analyzing the results we can get:
when UAV flies at low speed(0.3Ma~0.7Ma), the drag's difference between the two kinds of pod is
little, the pod's drag takes a small part of the UAV's whole drag which is only about 14%. At transonic
speed(0.8Ma~1.2Ma), the drag's difference between these two kinds of pod is getting bigger and bigger
along with the speed goes higher. The traditional pod's drag is 1/3 of the UAV's whole drag value, but
for the new pod, it is only 1/5. At supersonic speed(1.3Ma~2.0Ma), the traditional pod's drag goes up
rapidly, but the new kind of pod's drag goes up slowly. This makes the difference between the two
kinds of UAVs' total drag comes greater. For example, at 2Ma, the total drag of new UAV is only 2/3 of
the traditional UAV. These results show: when the UAV flies at low speed, these two kinds of pod have
little difference in drag. But if it flies at supersonic speed, the pod has great impact on the UAV's total
drag, so the designer of UAV's pod should pay more attention on the out shape.
It is essential to analyze the gimbal displacement errors for a seeker due to the importance for cueing of targets and
tracking for the final approach. Otherwise, for a seeker electro-driven with a concentric glass dome, the large errors will
decrease the picking, pointing, and tracking precision rooted from the displacement errors existing between the rotation
center of the optical system and the gimbal. And the gimbaled camera system displacement errors are never eliminated
but reduced due to the geometric errors consists of geometric tolerances of gimbal structure, manufacture, installation
and vibration coming from working environment.
In this paper, the gimbal displacement errors in an electro-optically stabilized platform resulting from geometric errors
and environment errors were analyzed and shown in detail. The mathematical modal of the gimbal displacement errors
created based on multi-body dynamics demonstrated the connection between the gimbal displacement errors and the
stabilized platform. Taking a visible light image seeker as a case, the diameter is 120mm, and the geometric tolerances
came from the values of primary design and the vibration data came from the environmental vibration test on the
pitch-yaw seeker, and at the same time, the errors resulting from installation were considered too. Based on calculating,
the maximum gimbal displacement error will reach to 0.2mm for pitching angle smaller than 40° and yawing angle
smaller than 60°. However, the critical parts have been found out according to the probability theory and the reliability
analysis successfully used in the paper, and finally, the maximum gimbal displacement error reduced to 0.1mm, which is
acceptable corresponding to the picking, pointing and tracking precision for an optical imaging seeker.
Optical guidance missiles requires a dome which fits both optical and aerodynamic needs when they attack at 3 Ma. In
this study, ellipse is the figure chosen to be the dome's shape. The ellipticity ε is the main variable should to be
decided. The optimized function was built by optical and aerodynamic performance function multiply by their weights.
The optical and aerodynamic functions were all obtained by computational fluid dynamic (CFD) simulation's results
after normalization. In this study, the optical and aerodynamic performances have equal weights, after optimzing the
ellipticity εis 2 for the missile.
Dome is the head of a missile which has such a strong effect on the missile's drag. When missiles attack at high speed,
the drag caused by sphere dome is 50%~60% of whole missile's drag . In order to reduce the dome's drag, the idea of
"conformal optics" is studied in some papers. The state of the art of conformal optics is described in James P.Mils paper
. But most people's work focus on the outside of dome's shape design. This paper presents a way to design the dome's
This paper is composed by three main parts. The first part expands the calculation of dome's outflow and the shock
wave. The second section describes how the optical optimizing function made. Finally, the last section shows the result.
In order to decrease the aerodynamic drag of supersonic image guide missile and design a non-spherical dome, the
outflow field of the missile's dome is simulated using FLUENT. Based on the simulated results, the accurate density
field of the outflow field at all kinds of flight conditions is obtained, and then the refractive index field of the outflow
field is gotten according to the Gladstone-Dale law. The results show that the shock wave induces the heterogeneity of
the refractive index field and the turbulent causes distortion. The outflow field is divided into several zones which are
taken as equivalent lenses for aberration analysis.