In view of the infrared athermalization design initial system difficult to make the selection, material requirements, introduced infrared material selection and sorting system, from the input parameters, to determine the initial system, this paper has fully modular programming. In this paper, the telephoto system combined with poor heat dissipation model, analyzed a perturbation type far infrared wavelengths passive design method of athermalizing lens. Deduces the relationship between the focal power allocation between them, and to unify the two directly by heat dissipation taken away and the difference between objective lens focal power allocation relation. Cut the infrared system selection process, radically reduce the infrared optical system design cycle. In order to verify the feasibility of this method, designed a long shots than 0.8, the range of temperature compensation for - 45 ° ~ 60 ° infrared wavelengths of athermalization telephoto lens.
As athermal design is an important issue in the field of infrared optical system design, this paper originated a test procedure on athermal design effect based on optical transfer function gauge. In this procedure, we let the optical system under test automatically focus first, then record its focus position under different temperatures, finally get the relative defocusing amount of the optical system under test under different temperature. This paper also developed a test system of a kind of athermal design effect, introduced its system composition and its working principle of measuring the defocusing amount, and gave the experiment results. The results suggest that it can focus fast, its repeatability is good, and it can resist noise interference with high precision.
On the basis of research on the theory of the Fourier transform lens, according to the observation and test requirements of a fine particle and the geometrical optics aberration theory, a particle size measuring lens of adjustable high resolution laser beam that worked for wavelength of 660 nm is designed, the laser beam can be controlled through the aperture adjusting device of the lens, and can high definition imaging for the semiconductor fiber laser that core diameter is 4.5μm, numerical aperture N.A is 0.13, the output wavelength is 660nm. In the case of object distance for the next 129.5mm, the spot diameter approximately equal to the theoretical amplification value, the main image spot is clear and no flare.
Based on the theory of athermalization, an optical system of temperature self-adaptive dual field of view was designed in this paper, appling in 3μm～5μm medium wave infrared camera system. This system achieved the design of optical passive athermalization by reasonable selection in terms of infrared optical materials and aspheric surface. Only five lenses were applied in this optical system, meanwhile, optical materials like germanium, silicon and ZnSe were all ordinary and cost-effective. The focal distance was 50mm/100mm, with total length of 125mm and pixel size of 17μm. The MTF of the two field of view were both greater than 0.5 at 30lp/mm in -45°C～+60°C, with its optical performance approximating the diffraction limit.