The invention discloses a measurement system of performance parameters of a charge coupled device (CCD) chip, which mainly solves the weaknesses that the present system does not have universality, measures the parameters incompletely and has narrow spectral coverage. The entire system comprises an adjustable monochromatic light source system (1), an integrating sphere (4), a darkroom (5), a Dewar bottle temperature control chamber (9), a picoammeter (10), a main control circuit system (11) and a main control computer (14), wherein a CCD to be measured and a standard detector are arranged inside the Dewar bottle temperature control chamber, the adjustable single-color light source system outputs monochromatic light, the monochromatic light is radiated onto the CCD to be measured and the standard detector after being converted to homogenous light by the integrating sphere and the darkroom, the CCD to be measured is driven by the main control circuit to image, the output information of the CCD is uploaded onto the main control computer, and the main control computer calculates the performance parameters of the CCD to be measured according to the image information. The measurement system has advantages such as strong universality, complete measured parameters and high stability, and is suitable for the measurement of all CCD chips.

Measurement system of performance parameters of charge coupled device (CCD) chip

The invention discloses an optical path structure for a concave grating diffraction efficiency tester and belongs to a concave grating diffraction efficiency tester in the technical field of light spectrum The invention provides an optical path structure for a concave grating diffraction efficiency test to solve the technical problem, and the technical scheme for solving the technical problem isthat: the structure comprises a light-source external optical path, a front monochromator, a measuring monochromator and a controller, wherein the light of the light-source external optical path is reflected by a condenser outside a shell of the front monochromator, is focused at an entrance slit and is transmitted into the front monochromator; emergent rays are transmitted into the measuring monochromator through an optical fiber; the measuring monochromator mainly comprises an incident optical arm, an emergent optical arm, an optical grating turntable and a photomultiplier; a standard concave mirror and a tested concave grating are successively arranged on the optical grating turntable for measurement; and the photomultiplier successively receives the reflecting luminous flux of the standard concave mirror and the diffraction luminous flux of the tested concave grating so as to finish the diffraction efficiency measurement of the concave grating The optical path structure is simpleand practical

Optical path structure for concave grating diffraction efficiency tester

The invention provides a device for measuring a material refractive index and a refractive index temperature coefficient under a low temperature, and the device comprises a collimation light source system, an optical spectroscope, an aiming system, a low-temperature vacuum cabin, a sample cabin, a double-sided rotary reflection mirror, an electric-control rotary platform and a collimator. When the temperature inside the sample cabin is reduced, the refractive index of a sample is reduced, a deviation angle delta also has slight variation delta, and the variation quantity of the deviation delta can be measured by the collimator, so that the refractive index of the material under the low temperature is changed. The device is based on the most conventional vertical incidence method, simple in principle and convenient to operate, a measured sample prism can be made of infrared materials and also can be made of the material in the visible light band, the application range is wide, the collimator is used for substituting a conventional coder for the measurement, the collimator is precise for measuring the slight variation of the angle, the collimator can be well applied to the slight variation of the deviation angle caused by the variation of the material refractive index under the low temperature, the cost of the device is reduced, and the measurement precision of the deviation angle is improved.

Device for measuring material refractive index and refractive index temperature coefficient under low temperature

In view of whether the optical system of a focal length 14~360mm continuous zoom TV can obtain high quality and high reliability images in high and low temperature environment, especially in extreme low temperature environment. The thermal design of zoom TV optical-mechanical system using passive thermal control and active thermal control is proposed. The passive thermal control uses polyimide as insulation material to increase the thermal resistance between the camera interior and the outside. Active thermal control uses electric heating film to dynamically heat the key parts of the camera lens. Under the condition of low temperature, the finite element method is used to establish the heat transfer model of the whole lens assembly in the workbench finite element software, and analyze the heat load composition, including the heating power load, the heat convection load and the heat radiation load, and carry on the steady state thermal analysis. Through thermodynamic analysis and experimental verification, the consistency of focal plane of zoom camera optical system is good after taking active thermal control measures at the extreme low temperature of -45°C. The optical transfer function (OTF) of zoom lens at cut-off frequency (100lp/mm) is 0.25 higher than that before thermal design, which can meet the requirements of thermal control design with better transfer function distribution and higher imaging quality. The correctness of the simulation results and the rationality of the optical-mechanical design are verified.

Thermal control design and analysis of a zoom TV optical mechanical system

The invention relates to a lens installing and positioning device in a cold optical technology, and relates to the field of low-temperature infrared. The lens installing and positioning device comprises a main lens cone, two lenses, a tetrafluoroethylene cushion, fine-thread adjusting screws, a mirror spacer ring, a lens pressing ring, pressure springs, pressing screws and a pressing cover. The first lens is positioned through cooperation of an oblique face at the front end of the main lens cone and an oblique face of the first lens, optical spacing between the first lens and the second lens is guaranteed through the mirror spacer ring, the mirror spacer ring is in oblique face fit with the two lenses, the second lens is pressed through the lens pressing ring, pressing force between the second lens and the lens pressing ring is realized through the pressure springs, connection between the pressing screws and the main lens cone is used for adjusting the pressing force, and the pressing cover plays a protective role. The lens installing and positioning device solves the problem of lens installing and fixing within a large temperature change range, can adapt to thermal deformation of the lenses and a supporting structure thereof within a large temperature change range, and guarantees that the lenses are not damaged irrecoverably while surface shape precision of lens surfaces is guaranteed.

Lens installing and positioning device in cold optical technology

The invention disclose a grating diffraction efficiency tester keeping an invariable incident angle, comprising an external light source system, a prearranged beam splitting monochrometor, a measurement monochrometor and a measurement control system, wherein, the outside of the shell of the prearranged monochrometor is provided with two slits which are respectively an entrance slit and an exit slit; the shell is internally provided with a grating dispersion beam splitting system; a diffraction efficiency measurement monochromator controls the direction of grating diffraction beam propagation by adding a rotatable plane reflecting mirror, adjusts the different diffraction directions due to the different wavelengths to enable the grating diffraction beam to be kept on one direction to entera converging objective lens, and finally images on a detector in a fixed position to finish measurement. The grating to be measured does not need to be rotated in the measuring process to realize theconsistence of the testing conditions, and the incident angle keeps invariable when the diffraction efficiency of different wavelengths is measured; and meanwhile, rotary plane reflecting mirror of the measurement system is controlled by a computer automatically, the automatic degree of the testing process is high, and the testing result is credible.

Grating diffraction efficiency tester keeping invariable incident angle

The invention discloses a lens fixing device used for a low temperature transmission optical system. A pre-tightening structure capable of stretching and retracting elastically is designed in the axial and radial direction, wherein an elastic press ring structure is adopted to conduct pre-tightening in the axial direction and absorb assembly stress generated by inconsistency between a lens and a lens cone caused by temperature change. Two symmetrical small boss arc faces are adopted at the position where the lower end of the excircle of the radial lens and the lens cone are contacted, simultaneously the upper end of the excircle of the radial lens adopts a cylindrical spiral compression spring for pre-tightening, so that enough gaps are maintained between the lens and the lens tube to prevent the lens from being deformed under low temperature and extrusion. Simultaneously, the structure is ensured to be centripetal and stable, and the optical axis direction is not changed. The lens fixing device can well guarantee that the optical system still has good optical performance under low temperature.

Lens fixing device

Cryogenic optical systems have a good capability and sensitivity in IR detection for its low
thermal radiation and background noise. In the past, most of the cryogenic optical systems were
reflective. It is very difficult to design refractive cryogenic optical systems because there is lack of
cryogenic, infrared refractive index data. In order to make the refractive optical systems designing
at cryogenic temperature possible, a cryogenic refractometer is very necessary.
In this paper, a new cryogenic refractometer is described. It is obvious that this new refractometer
should be integrated designed of structure, thermal and optical analysis. Based on the previous
research, the integrated structure, thermal and optical analysis procedure is established. The
cooling process of sample prism and acquired the temperature field of the sample prism and
sample chamber are simulated. According to the results of FEA, 3 changes might happen during
the cooling: the optical surface shape change of sample prism, the rigid-body movements of
sample chamber, and the stress birefringence of sample prism. The changed optical surface can be
fitted by a 36-terms Zernike polynomials, then the wavefront aberration of cooled sample prism
can be estimated. It may cause the stress birefringence in the sample prism during its cooling, so it
is very essential to estimate the change of refractive index which is due to the thermal stress.
According to the final results of the analysis, the refractometer can be optimized.

Opt-mechanical and thermal integrated analysis of a new cryogenic refractometer

In order to enable high quality infrared lens designs at cryogenic temperature, we decided to study the IR materials’
optical properties, such as the refractive index, the thermo-optic coefficient (dn/dT) etc. As a matter of fact, accurate
precision refractive index data for infrared optical materials at cryogenic temperatures is scarce, so we decided to design
a cryogenic absolute prism refractometer for infrared optical materials.
Considering the most accurate and precise measurements of the real part of the refractive index, n, optical materials are
obtained through minimum deviation refractometry, we decided to choose this classic refractometer for our cryogenic IR
materials index measuring. Given the thermo-optic coefficient of many IR materials, which was reported by NASA, the
measurement precision is at least 10 -3 . In order to achieve this precision, the error of apex angle of sample prism and
deviation angle must be less than 20 arc-second. The thermal stress of the prism must be in control, or the volume
change of the prism may lead to stress birefringence (photo-elastic effect). The bandwidth of IR source must be less than
20nm and the error caused by dispersion (dn/dλ) will generally be negligible in our system.
The hardware system consists of 5 subsystems: the rotating sample chamber subsystem, the rotating plat mirror
subsystem, the cryogenic vacuum subsystem, auto control subsystem, exit image collimation subsystem. Finally, the
system is designed to measure IR materials’ indices between 1-4, at the wavelength of 1.0-12μm, at room (300K) and
cryogenic temperature (100K), with a precision of 10 -4 .

Design of a cryogenic absolute prism refractometer for infrared optical materials

Cryogenic optical systems are often mounted in vacuum cryostat. An interesting concern in the mechanical design is how to maintain the stability of the line of sight (LOS) of the cryogenic optical system when it is cooled down to very low temperature. To investigate this problem an experimental cryogenic optical system, its mounting structure, and a cryostat were designed and fabricated. After assembling them together, a test experiment for measuring the LOS drift was carried out. Finally, the test results will be presented in this paper.

Qifeng Ren

Papers

Grating diffraction efficiency tester keeping invariable incident angle

Lens fixing device

Opt-mechanical and thermal integrated analysis of a new cryogenic refractometer

Design of a cryogenic absolute prism refractometer for infrared optical materials

Stabilization of the line of sight of a cryogenic optical system