JPH0290737A - Optical space transmitter - Google Patents

Abstract

PURPOSE:To facilitate the adjustment of the focusing of a light beam by reflecting the light beam sent from a transmitter in a collimated direction, picking up an image and adjusting the focus of the light beam based on the obtained image pickup signal. CONSTITUTION:The transmitter is provided with optical path loopback optical systems 48-50 reflecting the light beam LA1 sent from a light beam emission optical system 36 in parallel with an optical axis L of the light beam LA1, an image pickup optical system 52 leading a reflected light beam LA4 to a photodetection face of an image pickup device 45, optical spot detection circuits 60, 61, 63-65 detecting the size of a light spot SP1 based on an image pickup signal SE obtained from the image pickup device 45 and control means 42, 66-68, 70 controlling the distance between a light source 40 and a light beam radiation optical system 36. Then the sent light beam LA1 is reflected in parallel with its optical axis L and the image is picked up by the image pickup device 45. Thus, it is possible to detect the spread of the light beam LA1 and to adjust the focus by an optical space transmitter 1 only.

Description

[Detailed description of the invention] The present invention will be explained in the following order.

A. Industrial field of application B. Overview of the invention C. Conventional technology Problems to be solved by the invention E. Means for solving the problem (Figures 3 and 5) F. Effect (Figures 3 and 5) Figure) G Embodiment (Figures 1 to 17)) H Effects of the Invention A Industrial Application Field The present invention relates to an optical space transmission device, and is suitable for application to, for example, a bidirectional optical space transmission device. be.

B Summary of the Invention The present invention is an optical space transmission device in which a light beam sent out from a transmitting device is folded back in parallel to form an image, and the focus of the light beam is adjusted based on the insurance signal obtained as a result. Thereby, the focus of the light beam can be easily adjusted.

C. Prior Art Conventionally, in this type of space optical transmission device, a light beam is modulated with a desired information signal and the light beam is transmitted via a space optical transmission path.

That is, the transmitter modulates a light beam with a desired information signal and sends the light beam to an optical space transmission path.

On the other hand, in a receiving device, a light beam transmitted to an optical space transmission line is received by a light receiving element, and an information signal is demodulated based on an output signal of the light receiving element.

At this time, the spread of the light beam sent out from the transmitting device is adjusted so that the light beam sent out to the optical space transmission path is accurately focused on the light receiving surface of the light receiving element (hereinafter referred to as light beam focus adjustment). ), thereby ensuring that the desired information can be transmitted.

D Problems to be Solved by the Invention Conventionally, when adjusting the focus of a light beam, the receiving device repeatedly detects the focused state of the light beam and adjusts the spread of the light beam based on the detection results. However, there is a problem in that the focus adjustment work is complicated.

Furthermore, in order to communicate the detection results, a dedicated communication line such as a telephone line must be prepared, which poses the problem of complicating the overall configuration of the spectral space transmission device.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose an optical space transmission device that can adjust the focus of a light beam with an overall simple configuration.

E Means for Solving the Problem In order to solve this problem, the present invention includes a light source 40 that emits a light beam LAI modulated with an information signal;
A light beam emitting optical system 36 that sends out the light beam LAI to the receiving device; and an optical path folding optical system 48 that returns the light beam LAI sent out from the light beam emitting optical system 36 parallel to the optical axis of the light beam LAi. 49.50 and the folded light beam L folded back by the optical path folding optical system 48.49.50
Based on the imaging optical system 52 that guides A4 to the light receiving surface of the imaging device 45 and the imaging signal St obtained from the imaging device 45,
Returned light beam LA on the light receiving surface of the imaging device 45
The light source 40 and the light source 40 are Control means 42, 66, 67, 68, 70 for controlling the distance between the beam emitting optical systems 36 are provided.

F action If the transmitted light beam LAI is turned back parallel to its optical axis and imaged by the imaging device 45, the spread of the light beam LAI can be detected and the focus adjusted only on the optical space transmission device 1 side. be able to.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, l indicates a bidirectional optical space transmission device as a whole, which is housed in a housing 2 and is installed, for example, on the roof of a building.

On the operation panel 2A of the housing 2, together with the display device 3, there are a screen changeover switch 4A and a power switch 4B of the display device 3.
, switches 4C and 4D for horizontal and vertical optical axis alignment, a focus adjustment switch 4E, gain adjustment operators 5A and 5B for optical axis alignment by servo, and a display section 6 that displays the irradiation position of the light beam, etc. It is provided.

Furthermore, a receiving section 9 is provided on the operation panel 2A to receive a control signal transmitted from the remote commander 8, so that the remote The optical space transmission device 1 can be remotely controlled using the commander 8.

Further, in the operation panel 2A, a transparent cover l is provided to cover the display device 3, the operators 4A to 5B, and the display section 6.
O is attached via the screw 11, and after the cover IO is attached, the operators 4A to 4A are attached.
5B cannot be directly manipulated.

Therefore, when installing the optical space transmission device 1, the remote commander 8 is used to remotely control it.

In reality, in the optical space transmission device, the light beam LAI is sent out toward the transmission target far away, so if the optical space transmission device l vibrates even slightly, the irradiation position of the light beam LAI will change greatly. Change.

Therefore, for adjustment, the operators 4A~ on the operation panel 2A
5B may change the optical axis of the light beam LAI. Therefore, in this embodiment, instead of operating the operators 4A to 5B on the operation panel 2A, remote control is performed using the remote commander 8. Vibration can be effectively avoided by making adjustments.

Furthermore, attach the cover lO and operate the controls 48 to 5B.
By making it impossible to directly operate the display device 3,
, the controls 4A to 5B and the display section 6 are effectively protected from rain, dust, etc.

On the other hand, as shown in FIG. 2, inside the housing 2,
A transmitting/receiving optical system 20 is provided, and a light beam LA is directed from the optical space transmission device 1 to an optical space transmission device (having almost the same configuration as the optical space transmission device 1) to which information is to be transmitted.
It is configured to transmit the light beam I and also receive the light beam LB2 arriving from the optical space transmission device to be transmitted.

That is, the U-shaped pedestal 21 fixed to the housing 2 holds the annular holding member 22 on the shaft 24 using the supporting member 23.
It is pivotally supported above, and the direction of the optical axis of the light beam LAI emitted from the transmitting/receiving optical system 20 can be adjusted in the vertical direction.

Incidentally, the holding member 22 has a gear 25 that rotates around a shaft 24, and when the gear 25 meshes with a gear 27, the holding member 22 is rotated in the direction indicated by arrow a by a motor 26 fixed to the pedestal 21. This allows the motor 26 to be driven to adjust the direction of the optical axis.

The holding member 22 supports a cylindrical lens holding member 30 on a shaft 34 by means of a supporting member 31, and supports the light beam LAI.
The direction of the optical axis can be adjusted in the left-right direction.

Incidentally, the lens holding member 30 has a gear 33 that rotates around a shaft 31, and when the gear 33 meshes with a gear 34, a motor 35 fixed to the holding member 22 is connected.
It is configured to rotate in the direction indicated by the arrow, thereby driving the motor 35 to adjust the direction of the optical axis.

On the other hand, as shown in FIG.
In this case, a transmitting/receiving lens 36 is disposed on the front surface, and a laser light source 40 and a light receiving element 41 mounted on a slide table 37 are arranged along the optical axis of the transmitting/receiving lens 36.

The slide table 37 is moved along the optical axis as shown by the arrow C by rotationally driving the motor 42, thereby reducing the distance from the laser light source 40 and the light receiving element 41 to the transmitting/receiving lens 36. It is made to change.

By the way, the slide table 37 has a transmission/reception lens 36.
When the slide table 24 is moved away from the transmitting/receiving lens 36, the light beam is transmitted through the transmitting/receiving lens 36. After the LAI changes from a diverging light beam to a light beam with a small modulus to obtain a parallel light beam, the spread further becomes smaller and changes to a convergent light beam.

Thus, by rotationally driving the motor 42, the distance from the transmission/reception lens 36 to the laser light source 40 and light receiving element 41 can be adjusted.
The light beam LA1 emitted from the light receiving element 4 is adjusted to be a parallel light beam, and the light beam LB2 that has entered the parallel light beam is adjusted to the light receiving element 4.
The lens can be adjusted to focus on one light-receiving surface.

Incidentally, the laser light source 40 is configured to emit a light beam LA1 modulated with a predetermined information signal, thereby transmitting the information signal to the optical space transmission device to be transmitted.

On the other hand, the light receiving element 41 is configured to output an output signal to a predetermined signal processing circuit, thereby demodulating the information signal transmitted from the optical space transmission device to be transmitted to the optical space transmission device l. is being done.

Thus, the laser beam 'a40 constitutes a light source that emits a light beam LAI modulated with an information signal, whereas the transmitting/receiving optical system 20 as a whole constitutes a light beam that emits the light beam LAI to the receiving device to be transmitted. Configure the exit optical system.

On the other hand, inside the housing 2, there is a television camera 4.
5 is attached and roughly adjusted so that the optical axis of the television camera 45 and the optical axis of the light beam LAI roughly coincide.

The video imaged by the television camera 45 can be displayed on the display device 3 by switching the screen changeover switch 4A.
This allows the worker to confirm, via the display device 3, the approximate position where the light beam LAl is irradiated.

Furthermore, inside the housing 2, a collimating scope 46 is provided in front of the lens 42 and the television camera 45, and a collimating scope 46 separates a part of the light beam LAI.
It is designed to be guided to the television camera 45 parallel to the optical axis of I.

That is, the collimating scope 46 includes a half mirror 4 that is inclined at an angle of approximately 45 degrees with respect to the optical axis.
8 receives a portion of the light beam LAI, so that the light beam LAI travels straight and is reflected at an angle of approximately 90 degrees.

On the other hand, the half mirror 49 is the half mirror 48.
The beam LA2 is held in parallel with the mirror 48, and the reflected light LA2 of the half mirror 48 is transmitted therethrough and guided to the corner cube prism 50.

The corner cube prism 50 is arranged so that the reflected light LA2 is incident on its entrance surface 50A, so that the reflected light LA3 whose optical axis is parallel to the reflected light LA2 is
After being reflected by the corner cube prism 50, it is reflected by the half mirror 49, and the reflected light LA4 is guided to the television camera 45 via a lens 52 formed by the imaging optical system of the television camera 45. .

Therefore, by holding the half mirrors 48 and 49 at a high degree of parallelism, even when the collimating scope 46 is arranged at an angle with respect to the optical axis of the light beam LAI, as shown by the arrow e (i.e., (if the half mirror 48 is not placed at an angle of exactly 45 degrees with respect to the lens 42), and further via the corner cube prism 50,
By folding back the reflected light LA2 of the half mirror 48, even when the collimating scope 46 is arranged twisted with respect to the optical axis of the light beam LAI, as shown by the arrow f, the optical axis of the light beam LAI can be adjusted. The reflected light beam LA4 can be incident on the lens 52 in parallel.

As a result, the television camera 45 can obtain the light beam LA4 coming from the emission direction of the light beam LAI, and as shown in FIG.
At the same time, by imaging the transmission target through the window 53 provided in the collimating scope 46, the image of the transmission target is made into a t-layer image, and the light beam is projected onto the image of the transmission target. A brightly shining light spot SP1 can be detected at the LAI irradiation position.

Thus, the half mirrors 48 and 49 and the corner cube prism 45 constitute an optical path folding optical system that folds back the light beam LAI in parallel to the optical axis of the emitted light beam LA1, and the lens 52 folds back the light beam LAI in parallel with the optical axis of the emitted light beam LA1. An optical system is constructed to guide the reflected light beam LA4 to a television camera 45 consisting of a fil image device.

Further, in the collimating scope 46, shutters 55 and 56 made of liquid crystal optical elements are arranged between the half mirrors 48 and 49 and between the half mirror 49 and the window 53, and the shutters 55 and 56 are alternately opened and closed. By doing so, images of the laser light source 40 and the transmission target side are taken alternately.

That is, as shown in FIGS. 5 and 6, the vertical synchronization signal SV (sixth
(A)) is received by the counter circuit 60, and the shutter 56 is driven by a frequency-divided signal 5zv (FIG. 6(B)) whose signal level rises at twice the cycle of the vertical synchronizing signal Sv.

Furthermore, the frequency-divided signal S obtained via the inverting amplifier circuit 61
Inverted signal S of ty! The shutter 55 is driven by IV, thereby opening and closing the shutters 55 and 56 alternately with the period of the vertical synchronizing signal Sv.

As a result, during the period TI in which the signal level of the frequency-divided signal StV rises, only the transmission target side can be imaged via the television camera 45, and the screen changeover switch 4A
By switching, an image of the transmission target side can be obtained on the display screen of the display device 3 as shown in FIG.

Incidentally, in the image on the transmission target side, the light beam LB2 emitted from the transmission target toward the optical space transmission device l
As a result, brightness (light spora) SP2 (FIG. 7) is obtained at the installation position of the optical space transmission device to be transmitted.

Therefore, if the position of the optical spot SP2 is detected during the period T1 based on the video signal obtained via the television camera 45, the position of the optical space transmission device on the transmission target side can be detected. .

At this time, if the lens 52 is adjusted to focus on the building on the side of the transmission target, the distance from the transmission target to the optical space transmission device 1 will be long, so the light receiving surface of the television camera 45 will be In this case, it is possible to obtain a focused state for a beam of light arriving from almost an infinite distance.

Therefore, in the light spot SP2, when the light beam LB2 is a parallel light ray, the spot diameter is the smallest, whereas when the light beam LB2 is a diverging light ray or a convergent light ray, the spot diameter becomes correspondingly larger.

On the other hand, the inverted signal S! During the period T2 during which the IV signal level rises, only the laser light source 40 can be imaged through the television camera 45, and from this G, the laser light source is displayed on the display screen of the display device 3, as shown in FIG. Brightly shining light spot SP as 40 images
You can get I.

Therefore, as shown in FIG. 9, when the optical spora SP1 is emitted as a parallel ray, similarly to the optical spot SP2 (that is, when the laser light source 40 is placed at the focal position of the transmitting and receiving lens) ), the spot diameter is the smallest, whereas when the laser light source 40 is emitted as a diverging beam and a convergent beam (i.e., when the laser light source 40 is disposed at a position shifted from the focal point of the transmitting/receiving lens) , the spot diameter increases according to the spread of the light beam LAI.

Therefore, during the period T2, if the motor 42 is driven so that the spot diameter of the optical spot SPI is minimized based on the video signal S obtained via the television camera 45, only the optical space transmission device 1 side can be driven. So, the light beam LAI
can be adjusted to parallel light beams, and the focus of the light beam LAI can be adjusted with an overall simple configuration.

That is, as shown in FIG. 1O, in the optical space transmission device 1, when the focus adjustment switch 4E is turned on via the remote commander 8, the focus adjustment operation mode is entered and the optical spots SP1 and SP2 are scanned. Video signal SE whose signal level rises at the timing of
((AI) to (AN+5) . . . in FIG. 10) are applied to the waveform shaping circuit 63.

The AND circuit 64 performs logic at the rising edge of the signal level of the video signal SE via the waveform shaping circuit 63, and the signal level is set to logic r.
Waveform shaping signal S rising to HJ.

and the inverted signal S□9 whose open signal level rises during the period T2 is transmitted to the subcarrier signal S8. (Figure 10 (
B)), thereby outputting the subcarrier signal SSC to the counter circuit 65 during one scanning period of the optical spot SP.

The counter circuit 65 is reset in response to the inverted signal sztv, so that the light spot SP
Wave number Z of subcarrier signal SSC in one scanning period (in this case, wave number ZN*I obtained in each scanning line)
% ZH*z, consisting of the sum of ZH+3 and l+4) is detected.

Therefore, the spot diameter of the optical spot SPI can be detected based on the wave number Z of the subcarrier signal SSC, and in this embodiment, by driving the motor 42 so that the wave number Z becomes the minimum value. , light spot S
Adjust the PI spot diameter to the minimum.

That is, the latch circuits 66 and 67 connected in series are
The latch circuit 6 is driven by the frequency divided signal S2V.
By receiving the count value of the counter circuit 65 at 6, the count value of the counter circuit 65 is changed to □, which is the count value D! of the previous cycle. It is output to the subtraction circuit 68 at the same time as PH-1.

Therefore, when the laser light source 40 is moving toward the focal position of the transmitting/receiving lens 36, a negative count value DSF is obtained via the subtraction circuit 68, whereas when the laser light source 40 is moving away from the focal position. When, positive count value D
You can get SP.

The drive circuit 70 constantly drives the motor 42 at a very slow speed, and reverses the driving direction of the motor 42 when the count value DIF output from the subtraction circuit 68 is reversed.

In practice, the spot diameter of the SPI (light spot) becomes the minimum at the focal position of the transmitting/receiving lens 36 (Fig. 9), and the spot diameter remains the same even when the laser light source 40 moves forward or backward from the focal position. Since the diameter becomes large, even if it is possible to detect that the laser light source 40 is not at the focal position of the transmitting/receiving lens 36 by simply detecting the spot diameter, it is only necessary to move the laser light source 40 toward the lens 36. There is a problem in that it is not possible to detect whether the lens 36 should be moved away from the lens 36 or vice versa.

However, as in this embodiment, if the motor 42 is constantly driven,
By detecting a change in the spot diameter, it is possible to detect the position of the laser light source 40 with respect to the focal position based on the detection result, thereby arranging the laser light source 40 at the focal position and adjusting the light beam LAI. Focus can be adjusted.

Incidentally, the motor 42 is driven at a very slow speed so that a practically sufficient spot diameter can be obtained even when transmitting information while adjusting the focus.

(Then, as shown in FIG. 11, the latch circuits 66 and 6
7 constitutes first and second register circuits 71 and 72 that latch the count value D SPH and the value DSPN-1 at the timing of the frequency division signal Stv, whereas the subtraction circuit 68 latches the count value D SPH and the value DSPN-1 at the timing of the frequency division signal Stv. A comparison circuit 73 is configured to compare the value □-1.

On the other hand, the drive circuit 70 constitutes a motor drive circuit 74 for the motor 42, and an inversion circuit 7 that reverses the drive direction of the motor 42 based on the comparison result of the comparison circuit 73.
5.

Further, as a whole, the counter circuits 60 and 65, the waveform shaping circuit 63, and the AND circuit 64 constitute a light spot detection circuit that detects the size of the light spot SPI, whereas the motor 42, the latch circuits 66 and 67, and the subtraction circuit 68. The drive circuit 70 constitutes a control means that adjusts the distance from the laser light source 40 to the transmission/reception lens 36 based on the detection result of the light spot detection circuit.

Further, in this embodiment, the direction of the light beam LAI is adjusted based on the video signal S.

That is, as shown in FIGS. 12 and 13, in the direction adjustment circuit, the counter circuit 76 receives the waveform shaping signal S,
(FIG. 13(A)), and also provides the vertical synchronizing signal Sv (FIG. 13(B)) and the waveform shaping signal S to the flip-flop circuit 77. The time tl when the signal level of rises
After the logic level rises to the logic rHJ at , the logic level of the waveform shaping signal S rises to the logic rHJ at a time t
Output signal Sl whose logic level falls at 2 (Fig. 13 (
C)) and the horizontal synchronization signal S (FIG. 13(D)).

The counter circuit 79 generates an I/2 frequency-divided signal S2 (FIG. 13 (E
)) and the output signals of the AND circuit 78 are received via the OR circuit 80, thereby calculating the vertical distance 4 y + or Y2 from the scanning start end on the image to the center position of the optical spoiler) SP l or SP2. (Figs. 7 and 8), the number of horizontal scanning lines (i.e., as shown in Fig. 14, the video signal St (Fig. 14 (A1) to (AN+5)), the light spot from the start end of the rask scan. The distance to the center of the horizontal scanning line is determined by a value expressed in several tens of meters/2.

The multiplexer circuit 81 outputs the count (i!!Dy) to the latch circuits 82 and 83 alternately every one vertical cycle period.
As a result, the error Δy of the irradiation position of the light beam LAI with respect to the transmission target is output via the subtraction circuit 84 (Fig. 4).
It is designed to detect.

The drive circuit 85 drives the motor 26 so that the subtraction value representing the error Δy becomes 0, thereby adjusting the irradiation position in the vertical direction.

On the other hand, as shown in FIG. 15, the flip-flop circuit 86 outputs a horizontal synchronizing signal sK (FIGS. 14(B) and 15(A)) and a waveform shaping signal S, (FIG. 15(B)).
)), the logic level rises to the logic rHJ at the time t5 when the signal level of the horizontal synchronization signal SH rises, and then the logic level rises at the time t6 when the logic level of the waveform shaping signal S rises to the logic "H". falling output signal s
5 (Fig. 15(C)) is obtained.

The AND circuit 87 receives the subcarrier signal 5se (FIGS. 14(C) and 15(D)) together with the output signal S5, and outputs the output signal to the counter circuit 88, thereby causing horizontal synchronization. Signal S. After rising, the waveform shaping signal S is output at the optical spot SPI or SP2.
The period until the logic level of , rises to the logic rHJ can be detected by the wave number N of the subcarrier signal SSC.

The comparator circuit 89 opens the gate of the AND circuit 91 when the value N is less than a predetermined value.
The output signal of the circuit 87 is applied to a counter circuit 93 via an OR circuit 92.

In practice, there is an optical spoiler 1-5P l or SP on the scan line.
2, the logic level of the waveform shaping signal S is logic r
The signal level of the horizontal synchronizing signal S14 continues to rise on the scanning line without rising to HJ.

Therefore, by outputting the output signal of the AND circuit 87 to the counter circuit 93 only when the count value N of the counter circuit 88 is less than or equal to a predetermined value, the optical spoiler l-3 is generated on the scanning line.
The subcarrier signal SSC can be output to the counter circuit 93 only when Pl or SP2 exists, and thus the horizontal distance from the scanning start end to the light spot SPI or SP2 on the captured image can be calculated via the counter circuit 93 as a subcarrier signal SSC. It can be detected using the wave number N (FIG. 14) of the carrier signal SSC.

On the other hand, the AND circuit 94 outputs an output signal Sa(2) of the subcarrier signal Ssc via the counter circuit 95.
15(E)) and the waveform shaping signal S, and thereby outputs an output signal representing the spot diameter of the optical spot SP1 or SP2 with a delay time of one horizontal scanning period.
6 to the OR circuit 92.

As a result, the counter circuit 93 receives the subcarrier signal SS
After counting the wave number N of C, light spot SPI or S
Count the value M/2, which is 1/2 of the value M representing the size of P2, and thereby calculate jn (!! from the scanning start end on the image to the center position of optical spora) SP1 or SP2 in the horizontal direction. The distance MXI or Xt (FIGS. 7 and 8) can be detected alternately using the wave number of the subcarrier signal SSC (FIG. 14).

The latch circuits 97 and 98 are configured to sequentially receive the output signals of the counter circuit 93 in synchronization with the horizontal synchronization signal SN, and thereby output the count values DX of two consecutive scanning lines to the comparison circuit 99.

The comparator circuit 99 obtains a latch signal whose signal level rises when the count value stops changing after the count value DX of two consecutive scanning lines increases, and sends the latch signal to the latch circuit 1 via the multiplexer circuit 100.
01 and 102 alternately.

° On the other hand, the multiplexer circuit 103 transfers the output signal of the counter circuit PI93 to the latch circuits FIB101 and 1
02, thereby outputting the horizontal position data D□ and DX□ of the light spots SPI and SF3 to the subtraction circuit 104.

Thus, through the subtraction circuit 104, the two light spots S
By detecting the amount of deviation in the horizontal direction between P1 and SP2 and driving the motor 35 based on the detection result,
The irradiation position in the horizontal direction is adjusted.

That is, the drive circuit 105 detects whether the subtraction value representing the distance ΔX is a positive value or a negative value, and drives the motor 35 so that the subtraction value becomes O based on the detection result. .

In the above configuration, the light beam LAI emitted from the laser light source 40 and modulated with a predetermined information signal is emitted to the transmission target via the transmission/reception lens 36, and
The optical axis is bent parallel by a collimating scope 46 and guided to a television camera 45.

Thereby, in the television camera 45, an image of the laser light source 40 and an image of the transmission target side are obtained alternately in synchronization with the vertical synchronization signal Sv.

The video signal S output from the television camera 45 is converted into light spots SPI and SF via a waveform shaping circuit 63.
After being converted into a waveform shaping signal S whose logic level rises to logic rHJ at step 3, it is applied to a counter circuit 65 via an AND circuit 64, whereby the spot diameter of the optical spot SPI is detected.

The detection results are sequentially latched by latch circuits 66 and 67 and output to a subtraction circuit 68, which determines whether the laser light source 40 is moving closer to the focal position of the transmitting/receiving lens 36 or moving away from it. By reversing the drive direction of the motor 42 based on the detection result, the laser beam [40 is placed at the focal position of the transmitting/receiving lens 36, and is transmitted from the optical space transmission device l. The emitted light beam LAI is adjusted to parallel light beams.

According to the above configuration, the light beam LAI is folded back in parallel and imaged, and the spot diameter of the light spot 1-3P1 is detected based on the resulting video signal, so that only the light space transmission bag Ht side is detected. The light beam LAI can be adjusted to parallel beams.

Therefore, the light beam can be adjusted to parallel light beams without providing a communication path from the transmission target side to the optical space transmission device side, which was conventionally required. Focus can be adjusted.

In the above-described embodiment, a case has been described in which shutters made of liquid crystal optical elements are alternately opened and closed, but the present invention is not limited to this, and can be widely applied to other electric shutters, even mechanical shutters, etc. be able to.

In this case, as shown in FIG. 16 and FIG.
and 56 may be provided on the optical path and rotated by the motor 109 in synchronization with the vertical synchronization signal.

Further, in the above embodiment, the half mirrors 48 and 49 and the corner cube prism 50 are used to
Although the case where the AI is folded in parallel has been described, parallelogram prisms may be used instead of the half mirrors 48 and 49.

Further, in the above-described embodiment, a case was described in which the light beam LAI is adjusted to a parallel beam based on a video signal output from a television camera, but the present invention is not limited to video signals; The signal can be widely applied.

Furthermore, in the above-described embodiment, a case has been described in which the spot diameter of the optical spot (SPl) is detected based on the horizontal synchronization signal and the subcarrier signal, but the detection means is not limited to this, and for example, the detection means may be used to count other reference clock signals. It can be widely applied when

Furthermore, in the above embodiment, in addition to the spot diameter of the light spot SP1, the light spots SP1 and SF3 are
Although the present invention is not limited to this, it is also possible to simply detect the spot diameter of the light spot SPI and adjust the light beam LAI to a parallel beam based on the detection result. .

Further, in the above-described embodiment, a case has been described in which the laser light source 40 is moved to adjust the light beam LAI to a parallel beam, but in the present invention, the position of the lens may be adjusted instead.

Further, in the above-described embodiment, a case was described in which the focus is adjusted so that the light beam LA1 becomes a parallel beam, but the present invention is not limited to this, and the light beam LAI is adjusted so that it is emitted with a predetermined spread. You can do it like this.

Further, in the above embodiment, the present invention is applied to a bidirectional optical space transmission device configured to receive the light beam LB2 modulated with a predetermined information signal and sent out from the transmission target side. However, the present invention is not limited to a bidirectional optical space transmission device, but can also be applied to a unidirectional optical space transmission 'AM' that simply irradiates a light beam.

H Effects of the Invention As described above, according to the present invention, the optical space transmission device side is The focus of the light beam can be easily adjusted by simply using the above-mentioned method, and as a result, an optical space transmission device having a simple configuration as a whole can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a transmitting device of an optical space transmission device according to an embodiment of the present invention, FIG. 2 is a perspective view showing its transmitting and receiving optical system, FIG. 3 is a sectional view thereof, and FIG. 4 is a display image. 5 is a block diagram showing the optical space transmission device, FIG. 6 is a signal waveform diagram to explain its operation, and FIGS. 7 and 8 are
The figure shows a route map showing the displayed image when the shutter is switched.
Figure 9 is a route map for explaining focus adjustment;
The figure is a signal waveform diagram for explaining the operation of the optical space transmission device shown in FIG. 5, FIG. 11 is a block diagram showing the schematic configuration of the optical space transmission device shown in FIG. Block diagrams showing the adjustment circuit, FIGS. 13, 14, and 1
FIG. 5 is a signal waveform diagram for explaining its operation, FIG. 16 is a front view showing another embodiment of the shutter, and FIG. 17 is a route map showing the shutter placed on the optical path. 1... Optical space transmission device, 26.35.42...
...Motor, 40...Laser light source, 45.
Old...television camera, 46...collimating scope, 48.49...half mirror-15
0... Corner cube prism, 55.56.
·····Shutter.

Claims (1)

[Scope of Claims] A light source that emits a light beam modulated with an information signal; a light beam emitting optical system that emits the light beam to a receiving device; a light beam emitted from the light beam emitting optical system; an optical path folding optical system that folds the light beam parallel to the optical axis; an imaging optical system that guides the folded light beam folded by the optical path folding optical system to a light receiving surface of an imaging device; and an imaging signal obtained from the imaging device. a light spot detection circuit that detects the size of the light spot of the reflected light beam on the light receiving surface of the imaging device based on the detection result of the light spot detection circuit; 1. An optical space transmission device comprising: control means for controlling the distance between optical systems.