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For many years the automation research departments of the world have been using laser based analysis system to increase the understanding of the workings of the internal combustion engine. The laser has been incorporated into systems to measure drop size, velocity and vibration to name but a few. But few laser-based systems are able to aid the study of all these phenomena with the same system. The Applied Optics Group at Rover Groups Gardon Research & Development Center have been using just such a system and finding new uses for it all the time.

The system in use is a High Speed Imagining Division of Oxford Lasers LTD. The High Speed Imaging system comprises an Oxford Lasers LS20 Copper Vapor laser linked to a Kodak 4540 Digital High Speed Motion Analysis Camera capable of taking up to 40,500 digital frames per second. The Kodak 4540 records the images to DRAM memory allowing immediate play back of the recorded images for viewing, recording to videotape or to PC for analysis. The Copper Vapor laser acts as a short duration flash emitting pulses of only 30 nanoseconds in duration in full synchronization with the frame rate of the camera The flashes have the effect of reducing the exposure time of the camera, thus removing image blur due to the high speed of the subject under view, whilst maintaining image contrast due to the high intensity of the laser light. Another feature of the system is the ability to focus down the light. This has two benefits. The first is the ability to make laser light sheets for the 2 dimensional illumination of 3 dimensional subjects. This technique has great benefit when used to map the air flow into the combustion chamber of a running model engine. Not only can the air-flow be mapped but the progress of the flame front growth during the combustion cycle. The second is the ability to shine the laser light down a fiber optic cable. This aids in the illumination of areas of the running engine very difficult to access by normal optics. This has been particularly useful in the study of air motion in a variety of combustion system concepts.

The group plans to use the Copper Vapor laser to improve the ability of the technique to see these vibrations and therefore allow a better understanding of the cause of them. The technique could also applied to look at the airbag enclosure as it tears and composite materials under dynamic crush testing.

6. How many uses of the laser-based analysis system does the author want to show us?

[A] One [B] Two [C] Three [D] Much more than three

7. Which of the following does the High Speed Imaging system comprise ________.

[A] an Oxford Lasers LS20 Copper Vapor laser

[B] 4540 Digital High Speed Motion Analysis system

[C] DRAM memory allowing immediate play back of the recorded images for viewing

[D] a High Speed Imagining Division of Oxford Lasers LTD.

8. Which of the following is the main advantage of the laser flashes?

[A] Keeping image contrast [B] getting rid of image blur

[C] Increase the intensity of light [D] All is said in A, B, and C

9. Which of the following uses is NOT TRUE according to the passage?

[A] The laser light can help to make the three dimensional bodies look as if they were of two dimensions.

[B] The air-flow can thus be made easier to be mapped with the laser.

[C] The turning speed of the combustion engine can be accelerated by using vapor laser.

[D] The exposure time of the camera can be reduced by the laser flashes.

10. Which of the following can be the best title of the passage?

[A]At the Speed of Light

[B] A High Speed Imagining Division Made by the Oxford Lasers LTD.

[C] A Miraculous Application of Laser in Testing the Internal Combustion Engine

[D] Automobile research and Laser Technology

答案： D A D C C

（責任編輯：xll）

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