SU911450A1 - Device for recording hologram of object in counter beams - Google Patents

Description

(5k) DEVICE FOR RECORDING OF OBJECT HOLOGRAM IN COUNTERBRANDS

I

The invention relates to recording holograms of objects in colliding beams and can be used to record monochrome and color holograms.

A device for recording holograms consisting of a coherent radiation source, an expander, an object and a holographic photographic plate is known. The interferometer consists of a holographic photographic plate and an object. This is the minimum number of elements that makes the circuit resistant to vibrations 11 3.

The disadvantage of such a device is the absence of the possibility of changing the intensity ratio of the reference and object beams, since the dividing element in the interferometer is the holographic photographic plate itself and it is not possible to change its transmission, i.e. it is not possible to increase the diffraction efficiency of the system by fitting

optimal ratio of beam intensities.

The closest to the proposed technical entity is a device for recording a hologram in oncoming beams, containing a source of coherent radiation, a micro lens, a diaphragm, a lens for forming a light beam, and a photosensitive medium arranged in series.

10 In this device, a collimated beam of light is directed onto a holographic photographic plate, illuminating an object through it. Due to the collimation of the beam, the energy density of the radiation on the object is greater than that of the aforementioned device 2.

The disadvantage of the known device is the inability to change the ratio of the reference beams and the object 20, since in any plane parallel to the plane of the holographic plate from the object, the radiation energy density is constant. This leads to the fact that it is impossible to optimize the intensity ratio of the beams. The purpose of the invention is to increase the diffraction effect of the hologram hologram, which leads to an increase in the brightness of the reconstructed image. The objective is achieved by the fact that in a device containing a source of coherent radiation, a micro lens, a diaphragm, a lens for forming a light beam, a photoelectric flux, consequently, the lens of forming a light beam is located at a distance from the diaphragm that exceeds the focal distance, at the same time, the photosensitive medium is made with the possibility of movement along the optical ocfi device. FIG. 1 shows a device for recording a hologram of an object in colliding beams; in fig. 2 - the geometry of the scheme, necessary for clarifying the determination of the distance of the hologram to the object. The device consists of a coherent radiation source 1, a microscope 2, a diaphragm 3, a light beam forming lens k, a holographic photographic plate 5, and an object 6. The hologram is a glass substrate with a photosensitive layer applied. The device works as follows. The light beam coming from the coherent radiation source 1, for example a laser, falls on the micro lens 2, which expands it. An 8 microfocal lens 2 is located on the diaphragm 3 to increase the spatial coherence of the beam. The line for 4 light beam formations is located at such a distance from the diaphragm that the beam behind the lens converges. A holographic photographic plate 5 is installed in a converging laser beam. A light wave passing through a holographic photographic plate illuminates object 6 and, partially scattered on the F), is reflected back to the holographic photographic plate, this wave interacts with the wave traveling directly from source and reference wave, creating an interference pattern. The resulting interference pattern 04 p | eomodulated ,. and the depth of its modulation depends on the ratio of the intensities of the beams R, as well as on the vibration resistance of the installation. Since the light beam behind the holographic photographic plate is converging, the energy density increases with distance from the photographic plate. Therefore, setting the object at different distances from the holographic photographic plate, one can vary the intensity of the object beam in order to find the optimal value of the ratio R. Thus, the use of a collecting lens gives a significant advantage over the previously used systems, as it allows adjusting the intensity ratio interfering beams in a wide range. In the proposed device, such a distance b of the object from the holographic photographic plate is chosen, at which the ratio R is optimal. FIG. 2 shows the CD Holographic photographic plate; EF - object aperture; AV - aperture of the collecting lens; a is the distance from the collecting lens of the dog of the holographic photographic plate; b -. distance from the holographic photographic plate to the object; - the focal distance of the collecting LENSES Denoting the area of the holographic plate with tinki, illuminated by the incident wave,. S ,. - the area of the object. The area of a holographic plate, illuminated by a wave reflected from an SOP object, lens diameter D, from the similarity of triangles & AVK, D SPK and DER volume of -Са + ГГ i- (at2b) light is equal to f- with where If is the intensity of the light in the plane of the holographic photographic plate. The luminous flux (Fdg) reflected from the object is equal to (where IQ. Is the intensity of the luminous flux reflected from the object. Dog Kan rte CRC is the holographic transmission coefficient

photographic plates; light reflectance from objects

that Denote by K prf from {optimal recording of a hologram, as indicated above, it is necessary that R 1 or Fg g fdg

1G In

those. . Substitute value

- God IQ ,. get

Zl HgK. Spr 1gK -y. Sr SOP S, - If

Spr f - (a + 2b) i. - a f - (a + 2b)

К T b (1-Ю- (fa). Where is the value of a constant for this lens; and is the distance that the holographic photographic plate from the collecting lens is placed before removing the hologram. It is necessary to determine the value of K. It is known that photographs need to know the magnitude of the luminous flux reflected from the object forming the image on the film in order to correctly determine the support.For this purpose, an exposure meter is used.BUT unlike a normal photograph where the image is formed from one luminous flux, in holography for recording and the interference pattern requires two streams and, therefore, it is necessary to make two measurements, i.e., the intensity of the light flux coming from the source in the plane of the holographic photographic plate, and the intensity of the light flux, from 1U506

rage of object lor coefficient; K is determined from the ratio

og.

 and substituting his sign for the l 5 d d t value b.

Thus, setting the object from the holographic photoplate at a certain distance b, an optimal ratio of the intensities of the reference and object beams is obtained.

Claims (1)

The proposed installation also has high vibration resistance, since only two elements of the holographic plate and the object participate in it as an interferometer. The invention The device for recording 1 film of an object in opposite beams, containing a source of coherent radiation, a micro lens, a diaphragm, a lens forming a light beam, a photosensitive medium arranged in series, so that with the aim of increasing the diffraction the efficiency of the hologram, the lens of the formation of the light beam is located at a distance from the aperture exceeding its focal length, while the photosensitive medium is adapted to move along the optical si device. Sources of information, npin t «e into account in the examination. Denisyuk Yu.N. Optical holography. L., Science, 1979, p. 0. 2i Ostrovsky Yu.I. Holography and its application. L ,, Science, 1973, p. 36