SU1112907A1 - Optical transmitter - Google Patents

Description

an aperture and a photodetector connected to a registration unit associated with the signal processing unit. Using the specified lens and field diaphragm, the field of view of the receiving system is formed.

However, in this transceiver, the degree of background noise interference at the detector input is insufficient and, as a result, the sounding range is insufficient.

The purpose of the invention is to increase the range of sounding in the conditions of background noise by minimizing them at the input of the photodetector.

The goal is achieved by the fact that in a device comprising a radiation transmitter and a receiver including a lens, a field diaphragm and a photodetector connected to a recording unit associated with the signal processing unit, the lens is made as an anamorphic optical system of a long focus and short focus elements the optical axis of the radiation transmitter is aligned with the plane of symmetry of the lens parallel to the generator of the cylindrical surface of the long-focus element, and the focal distances of the ktiva bonded relation

2 U Whi fi 20S-yLo)

where fi and f2 are the focal lengths of the respective long-focus and short-focus elements of the lens;

The LO shadow region of the locator, i.e., the distance from the locator to the point where the transmitter beam completely enters the field of view of the receiver;

(ro is the divergence of the transmitter beam; / 5- the distance between the axes of the transmitter and the radiation receiver;

y is the angle between the optical axes of the transmitter and the radiation receiver.

Figure 1 shows the layout of the elements of the proposed transceiver; Fig. 2 is a diagram illustrating the principle of operation of the proposed device; FIG. 3 is a block diagram of the device.

Transceiver unit contains radiation transmitter 1, radiation receiver 2 consisting of a long focus lens forming element - an anamorph 3, a short focus lens forming element of an anamorph lens 4, a field diaphragm 5, photo detector 6. connected to a recording unit 7 connected with signal processing block 8 . One of the planes of symmetry of the receiver when

the intersection with the cylindrical surface of the long-focusing forming element of the anamorphic objective lens forms a straight line. Receiver 2 and transmitter 1

located in close proximity to one another, with the optical axis of the transmitter located in the plane of symmetry of the receiver, which is parallel to the cylindrical surface of the long-focusing lens forming element anamorphic 3.

The device works as follows (see, figure 2),

By means of the transmitter 1, light pulses are generated, which propagate along the optical axis of the transmitter and are scattered from objects being located along the propagation path of these pulses. The scattered back radiation enters the lens of the receiver 2. In the receiving system, various largest field angles are formed in two mutually perpendicular directions coinciding with the symmetry planes of the indicated

lens. In the plane passing through the optical axes of the receiver and transmitter, the largest field of view angle is formed, and in an orthogonal plane the value of the field of view coinciding with the angle of divergence of the locating beam (position 9 indicates the cross-section of the transmitted beam).

The angle of the receiver in the plane passing through the optical axes of the receiver and transmitter is represented by the relation. (i8-yU)

f2U

and in its plane orthogonal

d „

ff Figure 2 shows the relative position of the receiver and transmitter and the cross-section of the field of view of the receiving system 10 for

two times ti and t2. The dotted line shows the cross section of the field of view of the receiving system of the known device. 2, it can be seen that the cross-sectional area of the field of view of the device proposed is smaller,

than the famous. Consequently, the magnitude of the solid angle of the receiving system of the proposed device at a fixed range is less than that of the known. Since the magnitude of the background noise coming in

the input of the photodetector is proportional to the magnitude of the solid angle of the receiver, then the input of the photodetector in the proposed device receives less background noise than the known one. The distance of the location is inversely proportional to the amount of background light entering the photodetector input, therefore, the proposed device allows, under background light conditions (for example, during the day), to increase the distance of the location in comparison with the known one. The operation of the device as a whole is shown in FIG. The powerful pulse generated by the transmitter 1 is scattered in the atmosphere and partially falls on the receiving device 2. The signal is then sent to the recording unit 7 and then to the processing unit 8. The recorder is a real-time analog-to-digital converter that satisfies the signal parameters for time resolution and dynamics (for example, F-707.7). As a processing unit, a computing complex can be used on the basis of any commercially available digital computer (for example, Electronics-60) and a software-based data processing algorithm, depending on the type of task being solved (for example, the calculation of atmospheric transparency, the calculation of meteorological visibility range, etc.) . The power of the light at the input of the photodetector is determined by the expression P (t) Pc (t) + N, (2). Where Po (t) is the power of the back scattered radiation signal: N is the power of the backlight. In turn, the level of ambient light is defined as N Q A L N K, B, (3) where Q is the solid field angle of view of the receiver; And - the area of the entrance aperture of the receiving telescope: AY-spectral interval; Kjt is the transmittance of the receiving telescope for the wavelength I; . Bji is the spectral brightness of a portion of the sky in the probed direction. The distance of the location is determined from the laser location equation K-jgii -t where K is a hardware constant; In || - backscatter coefficient; T-transmittance of the atmosphere; K - sounding distance. From the relation (3) and (4) the maximum sensing range is found (4) K - /, | -T V From the expression (5) it follows that with decreasing background illumination the sensing range increases. In turn, the background illumination power of the receiving system is proportional to the field of view of the receiving system, see expression (3). In the proposed device, as a result of using an anamorphic optical system oriented in a certain way with respect to the radiation transmitter, the field of view of the receiving system is a solid angle optimized with respect to the dimensions of the beam being located. Comparing the solid angles of the field of view of the receiving systems of the known and proposed device (see FIG. 2), it can be determined how many times the magnitudes of the background light entering the photodetector input differ from one another Il Sl IX „--JTLIn T2 S2 where TI and T2 is, respectively, the solid angle of the field of view of the known and proposed devices; Si and $ 2 is the cross-sectional area of the field of view of the known and proposed devices, respectively, at the same distance from the locator. For a known device with equal angle of view of the receiving system with two values of the angular dimensions of the beam to be located, the value of Si is determined as Si 4 lt 12 g where r is the radius of the section of the beam being located. The sectional area of the field of view of the proposed device can be estimated from the calculations of the described rectangle around the sectional figure, while this estimate is somewhat overestimated. S2 8r Thus, the value of K for these conditions is 1.5, i.e. so many times in the proposed device, the amount of background light at the input of the photodetector is less. An example implementation of this device is an optical locator consisting of a receiver and a transmitter of radiation. The transmitter includes a source of radiation and a transmitting antenna. An ARZNI-207 optical quantum generator can be used as a radiation source, and a TO-1.000 type lens / mirror lens can be used as a transmitting antenna. The radiation receiver consists of a lens, a field diaphragm and a photo detector. As a lens of the receiver can

Cylindrical lenses with focal lengths fi 1200 mm and f2 280 mm are used. .

The field diaphragm is a round (1 mm) or rectangular (1 x 1 mm) hole in an opaque screen that is installed in the focal plane of the receiving lens on its optical axis. AT

A photomultiplier tube PMT84 can be used as a photodetector.

The proposed device has a greater range of location in conditions of background illumination with the same weight and dimensional characteristics than the prototype.

Fmg.2

3

Claims (1)

(54X57) OPTICAL RX TRANSMISSION DEVICE containing a radiation transmitter and receiver including a lens, a field diaphragm and a photodetector connected to a registration unit connected to a signal processing unit, in order to increase the sensing range by minimizing background illuminations at the input of the photodetector The lens is designed as an anamorphic optical system of length