Infrared camera and CCD camera dual-band imaging system is used in many equipment and application widely. If it is tested using the traditional infrared camera test system and visible CCD test system, 2 times of installation and alignment are needed in the test procedure. The large-aperture test system of infrared camera and visible CCD camera uses the common large-aperture reflection collimator, target wheel, frame-grabber, computer which reduces the cost and the time of installation and alignment. Multiple-frame averaging algorithm is used to reduce the influence of random noise. Athermal optical design is adopted to reduce the change of focal length location change of collimator when the environmental temperature is changing, and the image quality of the collimator of large field of view and test accuracy are also improved. Its performance is the same as that of the exotic congener and is much cheaper. It will have a good market.
Infrared camera has more and more application in military, judicature, rescue, industry, hospital and science. Nowadays
the NETD (Noise Equivalent Temperature Difference) of high-sensitivity cooled infrared camera is less than 10 mK. If
we test the NETD from the analog video output port of infrared camera using 8-bit and 10-bit ADC frame grabber, the
NETD accuracy is 7.81 mK and 2.76 mK which correspond to relative error 78.7% and 27.6% for a 10 mK NETD
infrared camera. Such kind of accuracy is obviously not proper for the performance evaluation of high-sensitivity
infrared camera with NETD less than 10 mK. The NETD test accuracy can be improved by increasing the effective bit
number of the ADC of frame grabber. The quantization error of ADC of frame grabber has become the main factor
which contributes most to the NETD error of the high-sensitivity infrared camera. It is difficult to evaluate the electrooptical
performance of the high-sensitivity infrared camera through its analog video.
Although the NETD test accuracy can be improved by reducing the linear temperature range or increasing the effective
bits of the ADC of frame grabber under analog video interface test condition, it is difficult to meet the test needs. But
under the 14 bits digital video interface test condition and 1 K linear range, the NETD test accuracy of 0.24 mK can be
achieved. The NETD accuracy can be also improved by reducing the linear temperature range. The NETD test accuracy
can be 0.488 mK through 14-bit digital video under 2 K linear temperature range and its relative error equals 4.9% for a
10 mK NETD high-sensitivity infrared camera which meets the requirement. The test result through the digital video
port of an infrared camera shows that the test result through digital video port matches with its nominal value. This
necessitates the need of digital video interface of high-sensitivity infrared camera in NETD test in order to evaluate its performance accuracy.
Several models of target acquisition range prediction of the uncooled staring camera and their advantages are proposed in the paper. NVTherm is used to evaluate the modulation transfer function, minimum resolvable temperature difference and target acquisition range. The analysis result shows that the performance of the detector is the key factor to limit the performance of the uncooled staring camera. The target acquisition range of the uncooled infrared camera can be improved by increasing effective focus length (EFL) of optical component, decreasing its F/# or reducing the pixel pitch of the detector. The detection range of 1.09 km can be achieved under the condition of 75 mm EFL and F/0.8. When the EFL changes from 75mm to 150 mm under the condition of F/0.8 and 45μm pixel pitch, the detection range of 2.36 km, recognition range of 0.47 km and identification range of 0.24 km have been gotten. When the pixel pitch is reduced to 35μm, the detection range is 2.59 km. Furthermore, when 2 x 2 microscan is adopted in the camera design, then the pixel pitch will change from 35μm to 17.5μm. Although the infrared camera becomes an optical performance limited system, its performance improves a lot to get the detection range of 2.94 km. The field test shows that the detection range to a 1.7 m x 0.45 m target is 2.2 km under the condition of F/0.8, 150mm EFL and 45 μm pixel pitch, achieving good matches with the evaluation value of 2.36 km through NVTherm. An optimum uncooled infrared design is achieved using the NVTherm software which shortens the design cycle.
A new binary image lossless compressing method is proposed, which regards a binary image as being constructed of a limited number of fractal elements that have undergone a series of operations such as contraction/dilation, embedding and jointing. Therefore, coding compression for an image is mainly a process of acquiring its specific fractal structure. This algorithm defines 16 basic elements of size 2x2, which can be dilated to power of 2 or put together side by side when of the same type to make up a self-similar element set in different scales. This element set constitutes the codebook of fractal-like-coding. Prior to coding, it is necessary to carry out decorrelation operation of an image and then perform sliding matching on the image with the elements to find the best matching element that meets appropriate matching merit. Record the error subimage that may have formed owing to incomplete matching. Then carry out dynamic segment designates coding for the error image featuring a sparse matrix form. Finally perform arithmetic coding for the code characters sequence obtained. It has been demonstrated by testing images of different complexities that the new method is very efficient to encode binary images.
Hand held uncooled Staring Infrared Camera has extensive domestic applications in China. A practical and low cost infrared starring camera has been designed and built. The prototype infrared camera is configured in three separate units: a signal acquiring unit, signal processing unit and the battery supply. The system design method of Uncooled Staring Infrared Camera based on 320 x 240 Uncooled Focal Plane Array (UFPA) is proposed. The paper discusses its performance and reviews the prospect for future developments.