RU96288U1 - SYSTEM OF SHADOW PHOTOGRAPHING OF A QUICK PROCESSING PROCESS - Google Patents

Abstract

 A shadow photographing system for a fast-moving process associated with the high-speed movement of the object of study, containing a pulsed light source, the start time of which is synchronized with the moment the object appears in the registration zone created by the source, a cassette with a wide-format open film opposite the source, placed in a lightproof casing with input and output windows for through movement of an object in the registration zone and a hole that ensures the accuracy of the light source, etc. than the photosensitive layer opposite the film filter set, characterized in that the filter used fotoelektropreobrazovatel adjustably light transmittance in the process of photographing, and in the initial state and the light sensitivity of the film transmittance matched filter.

Description

The utility model relates to optical registration systems, namely, photographic registration systems for fast processes and can be used for optical diagnostics in studies in the field of aerodynamics, gas dynamics, ballistics, etc.

It is well known (A.V. Fomin General course of photography, M. "Light Industry", 1974) that photographing on film (a CCD) located in the camera (camera with lens) is accompanied by a decrease in image size compared to the true size a subject (approximately L / f times, where L is the distance to the subject, f is the focal length), and a decrease in resolution (lin (pc) / mm) due to the native resolution of the lens. Meanwhile, for a number of applications, it is necessary to visualize processes or objects with a size of the order of 0.1 mm, which requires photographic recording with a full-scale image.

A well-known system of shadow photographic registration on an open film ("method of the luminous point") (GD Salamander. Photographic methods for studying fast processes. M., "Science", 1974, p. 8, Fig. 1-2.) In the dark days in open (field) conditions. The system includes a pulsed light source that creates a diverging or parallel beam of rays and is synchronized at the time of launch with the moment the object appears in the registration zone created by the source, as well as a cassette with wide-format open film.

The operation of the circuit is based on the supply of a light pulse from a pulsed light source to the region of registration of the object of study (flying model) at the time it passes near the photographic material (film). The change in the refractive index of a perturbed gas (the Lorentz-Lorentz law) that occurs when the model moves in air leads to a change in the path of the source rays and redistribution of illumination in the registration zone. This makes it possible to visualize optical inhomogeneities in the shadow image and obtain a spectrum of the flow around the model.

The disadvantage is the lack of the ability to implement the circuit under test conditions, accompanied by backlighting, i.e. when registering processes accompanied by self-luminescence and occurring outside the radiation exposure range associated with the operation, in particular, of an accelerating device (for example, an exhaust of a powder ballistic installation, expansion of explosion products of an explosive throwing device, etc.).

A known system for shadow photographing a fast-moving process associated with the high-speed movement of the object of study (RF patent No. 76166, 09/10/08), containing a point pulsed light source, the launch moment of which is synchronized with the moment the object of study appears in the registration zone created by the source, as well as a cassette with a widescreen open film. In this system, a cassette with a film is placed in a lightproof casing with input and output windows for the through movement of an object in the registration zone and a hole that ensures the accuracy of the light source, a film filter is installed in contact with the photosensitive layer of the film, the transmission spectral curve of which is selected from the background film exposure backlighting to blackening densities of 0.2-0.5.

The disadvantage of the system is that, despite the exclusion of the influence of background illumination on the photographing results, the presence of a filter limits the spectral component of the light pulse.

The task is to skip the full spectrum of radiation that covers the maximum sensitivity spectrum of the film at the moment of exposure of the object under study by a pulsed light source.

The technical result of the utility model consists in eliminating the influence of the light filter on the spectral characteristics of the recorded process in the absence of the influence of background illumination on the results of shadow photographic recording.

The technical result is achieved by the fact that, in contrast to the well-known shadow photographing system for a fast-moving process, accompanying the high-speed movement of the object of study, containing a point-like pulsed light source, the launch moment of which is synchronized with the moment the object appears in the registration zone created by the source, as well as a cassette located opposite the source with wide-format open film, and the cassette with a film is placed in a lightproof casing with input and output windows For through movement of an object in the registration zone and a hole that ensures the accuracy of the light source, and opposite the photosensitive layer of the film, a light filter is installed, the photoelectric converter is used as a filter in the proposed system with the ability to control the light transmittance during photography, and in the initial state the film sensitivity and light coefficient light filter transmission matched.

The choice of a photoelectric converter as a light filter, characterized by the ability to control the light transmittance, provided that the sensitivity of the film and the transmittance of the filter in the initial state are consistent with the light transmission, allows us to exclude the influence of the filter on the results of shadow when registering fast processes associated with high-speed movement of objects moving with hypersonic speeds photorecording and avoiding spectrum limitations cheniya light source, while reducing the influence of background illuminations.

Fulfillment of the condition for matching light transmission will improve the quality of registration when using the solution for any types of film widely used in photography (panchromatic, isopanchromatic, orthochromatic).

Figure 1 schematically shows the inventive system, where:

1 - pulsed light source with energy storage;

2 - cassette;

3 - film;

4 - lightproof casing with inlet and outlet windows and a hole that ensures the accuracy of the emitter;

5 - photoelectric converter (light filter);

6 - automation unit with a power source;

7-object of study.

According to figure 1, the light source (1) and the cassette (2) with photographic film (3) are placed in a light-tight casing (4) with input and output windows and an opening that ensures the accuracy of the light source (1). A pulsed light source (1) is triggered when a moving research object (7) appears in the registration zone. The fast-moving process accompanying the movement of the object is recorded on photographic film (3), a photoelectric converter (light filter) (5) connected to the automation unit (6) is placed in front of the film, and the light transmission coefficient of the filter is regulated by a signal from it. The signal delivery time is calculated on the basis of the condition for excluding the influence of background illumination on the photographic recording process. The film and the filter in the initial state are consistent in transmitting light.

A test procedure has been developed that focuses on the use of an SVD rifle with a caliber of 7.62 mm with an initial bullet speed of 820 m / s as an accelerating device. For optical registration using the shadow method, a mobile stand for shadow photo-registration was designed and manufactured. The cassette (2) with the film (3) is enclosed in a wooden casing (4), glued with black paper. The accuracy of the light source (1) is provided by a hole made in the casing opposite the film. When a film contact sensor installed at the entrance to the stand breaks through, a positive pulse is formed with an amplitude of 30 V, which is fed to the input of the discrete delay unit (BDZ). The time interval associated with the distance from the contact sensor to the photographic registration zone and the bullet speed in this section is set in the BDZ. BDZ in a specified time interval launches a pulsed light source (1), which performs photographic recording of a flying bullet (6) and its spectra flowing around onto a film (3) installed in a special cassette (2). The exclusion of the influence of the light filter on the spectral characteristics of the recorded process in the absence of the influence of background illumination on the results of shadow photographic recording is provided in the implemented version by means of an automation unit tuned to the light radiation of the background illumination, which controls the photoelectric converter shading the photosensitive layer of aerial film (isopanchromatic in the prescribed mode during registration) ) type 52.

The photoelectric converter in the open state has a transmittance close to unity, allows the film to be exposed to an unlimited spectrum of light radiation from a pulsed light source. As a result of shadow photographic registration of a fast-moving process, an image of a bullet with a caliber of 7.62 mm and the accompanying movement of a shock wave and a turbulent wake was obtained.

Thus, the choice of the type of filter and the features of its mode of operation make it possible to avoid limiting the spectrum of light radiation while eliminating the influence of background illumination on the photo image of the investigated fast-flowing process.

Claims (1)

A shadow photographing system for a fast-moving process associated with the high-speed movement of the object of study, containing a pulsed light source, the start time of which is synchronized with the moment the object appears in the registration zone created by the source, a cassette with a wide-format open film opposite the source, placed in a lightproof casing with input and output windows for through movement of the object in the registration zone and the hole, ensuring the accuracy of the light source, etc. than the photosensitive layer opposite the film filter set, characterized in that the filter used fotoelektropreobrazovatel adjustably light transmittance in the process of photographing, and in the initial state and the light sensitivity of the film transmittance matched filter.