Search

To eliminate the scatter light and central ghost in a classical fundus camera,the optical system of a catadioptric fundus camera with a field of view 40° and a working distance of 48 mm was designed.An off-axial reflecting ophthalmic lens with free form surfaces was designed to correct the off-axial aberrations.Two free-form-surfaces were introduced in the imaging objective system to correct the residual off-axial aberrations of the reflective ophthalmic lens.In the optimization of the imaging system,an eye model with varying defocuses was proposed to eliminate the negative effect of eye aberrations as well as to accommodate the eye with different refractive errors.Three adjacent illumination rings were introduced in the illumination part to avoid the undesirable light reflected by the eye optical system.Experiments show that the accommodation range of the system is between-10 m-1 and 10 m-1,the resolution at the object plane is 33 lp/mm across the entire field of view,and the maximum distortion is less than 8.5%.Furthermore,the illumination non-uniformity is less than 15% in the conditions without scatter light and central ghost.The designed catadioptric fundus camera with a free-form-surfaces show a satisfactory large field of view and a large working distance,and removes the undesirable scatter light and central ghost greatly.

To solve the problem of poor roughnesses for heavy curved freeform surfaces in prism processing,a Head Mount Display(HMD) prism with decentered aspheric surfaces was developed.All the optical surfaces of the prism were rotationally symmetrical aspherics,which showed a better processing property as compared with freeform surfaces.A short focal length and a large field of view were obtained by controlling the surface curvatures and tilt angles,and the aberration was corrected by optimizing aspheric coefficients.Experiments show that the HMD prism has an exit pupil of 6 mm and a field of view of 55°.At the frequency of 30 lp/mm,the axial Modulation Transfer Function(MTF) is over 0.2,the off-axial MTF is over 0.1,and the maximum distortion is-5.37%.The test and experiment on the prism demonstrate that the surface roughness has been greatly improved to a lower level for the aspheric surfaces,which avoids the image blurring and improves the performance of visualization.

In order to simulate the equivalent radiation environment of target and interference in the IR guidance process,and compare the effect of differences in target thermometry between monochromatic thermometry and chromatic thermometry under complex environment,the target and interference on space 6 km is simulated using IR dual color composite simulation system.Through the IR thermal imager calibrated accurately,the target and interference at different temperatures is tested using two methods of temperature measurement-monochromatic thermometry and chromatic thermometry.Blackbody temperature is measured by calibrated MW thermal imager and calibrated LW thermal imager,in the range from 25 ℃ to 40 ℃ of Blackbody temperature,the absolute error limit of LW thermal imager is 0.5 ℃,and in the range from 50 ℃ to 120 ℃ of Blackbody temperature,the absolute error limit of MW thermal imager is 0.2 ℃.When the target temperature is 500 ℃ and the interference temperature is 1000℃,the temperatures of target measured with LWIR,MWIR and chromatic thermometry are 28.5 ℃,148.3 ℃ and 322.4 ℃,and the temperatures of interference are 56.7 ℃,223.2 ℃ and 660.1 ℃ respectively.The experiment result indicates that the characteristics of target temperature can be better reflected using chromatic thermometry than monochromatic thermometry under complex environment.

For the requirements of the infrared imaging system performance testing and evaluation applications,an athermalized mid-wave infrared scene projector was designed,based on Digital Micro-mirror Device(DMD).The aberration and design method of the optical system for infrared scene projector were analyzed,and the athermalization for the scene projector was also discussed.A splitting lens and a compensation lens were used to address the light splitting and aberration balancing problems in the illumination of the telecentric projection systems with a large relative aperture.So the resolution and uniformity were improved,and the field of view was increased.The optical system is composed of a telecentric projection lens and a Kohler illumination lens with tilted image plane.The optical passive athermalization method was introduced into the design,which improved the stability of the system.The spectral band of the system is 3～5 μm,the focal length is 255 mm with a F/2.6 relative aperture,the field of view is 5.1°,and the exit pupil distance is 200 mm.The image quality of the system approaches diffraction limit with MTF0.6 at spatial frequency 17 lp/mm in the whole operating temperature range of-20 ℃~ 60 ℃.The proposed athermalized mial-wave infrared scene projector has the advantages of high resolution,excellent uniformity,compact size and low weight.

A high efficient,compact,Refractive / Total internal reflection / Reflective / Refractive(RIXR) collimating system was designed and optimized to collect a wide angle range light to emit the collimating beam with a small divergence angle.Firstly,the surface of the initial structure of the system was calculated according to the edge-ray principle and Simultaneous Multiple Surfaces(SMS) method based on the non-imaging optics theory.Then,the initial structure was optimized by using Zemax optical design software.Finally,the best LED collimating system was successfully designed.According to the results of the design,the semi-diameter of the RIXR collimating system is 20 mm,aspect ratio is 0.25 and its collection angle is 200°.These results indicate that the system can completely collect the light emitted by LED sources.As the root mean square radius of a spot diagram for the edge field(± 3.178°)obtained by the reverse ray tracing is less than 2.1 μm,the edge field shows an excellent focusing effect.Furthermore,when the light absorption loss of the material and reflection loss of the interface are fully considered,the light energy utilization rate is as high as 83.48%.Experiments demonstrate that the RIXR-type collimating system has advantages in a compact structure,high light energy utilization ratio and easy to use.

In order to switch the dual Field of View Infrared optical system quickly,and satisfy the requirements of the portability and installation,a lightweight hybrid refractive-diffractive dual FOV IR optical system is designed.The system adopts re-imaging and hybrid refractive-diffractive system,is optimized by optical design software,and the image quality is also evaluated.The temperature compensation is also analyzed,and the temperature compensation curves are also shown.The system can be switched from 120 mm/60 mm and the work wavelength is between 3.7～4.8 μm.The results indicate that the efficiency of the cold shield is 100%;at the Nyquist frequency 33 lp/mm of the detector,the MTF of the off-axial field is higher than 0.3,and the system's optical length is 200 mm.The whole system consists of 7 pieces of lenses,and the dual FOV can be switched by shifting only one piece of them,which makes the system simple,lightweight with high quality imaging.

In order to extend visualized detection to near ultraviolet and near infrared waveband for industrial testing,under the requirement of achromatic and passive thermal design,broad-waveband optical system working in 300～1 100 nm range is designed,and prototype for industrial testing is developed.Inverted telephoto construction is adopted to achieve an enough back focal length,and splitting the optical beams into three is achieved by insetting a coating prisms within the back focal length,near ultraviolet,visual and near infrared are imaged in three beams respectly.Reasonably lens material is chose to realize achromatic design.The system is passive thermal by moving a lens.The designed system has a field-of-view of ±3.5°,the effective focal length,F/#,back focal length and total length is 66.5 mm,3.3 nm,63 mm and 132 mm respectively.The results indicate that all MTF is more than 0.3 at 50 lp/mm,and a good performances is achieved over a temperature range(-10～+50)℃,the image requirement is met.Prototype exhibit excellent resulting during experiment.The system gathers as much information as possible about the detected objects by extending waveband,and a good advantage is exhibited in industrial and agricultural testing.