JPH045352B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a laser light warning device that can detect laser light and know the direction of arrival of the laser light.

(Prior Art) Conventionally, this type of laser light warning device has a photodetecting element array 3 in which a plurality of photodetecting elements 4 are arranged in an array at the focal position of a condensing lens 2, as shown in FIG. The photodetecting elements are connected by a single resistor or by impedance elements 6, 7, 8, etc. composed of resistors, inductances, and capacitances.

Now, if the laser beam 1 is irradiated onto the laser beam warning device, the laser beam 1 is focused by the condenser lens 2 onto a condensing point 5 on the detection element array 3.
A photocurrent I corresponding to the intensity of the laser beam 1 is generated in the photodetector element 4 disposed at the focal point 5 . This photocurrent I is divided into two parts by impedance elements 6, 7, 8, etc. according to the position of photodetector element 4, and is input to current-voltage conversion circuits 9, 10. Assuming that the impedance of the impedance element is Z, the number of impedance elements is M, the position of the photodetecting element where the laser beam is incident is N, and the outputs of the current-voltage conversion circuits 9 and 10 are V ₉ and V ₁₀ , respectively, V ₉ = αI・NZ/M・Z=αIN/M V ₁₀ =αI・(M−N)Z/M×Z=αIM−N/
It becomes M. α is the current-voltage conversion rate of the current-voltage conversion circuits 9 and 10.

These two voltage outputs V ₉ V ₁₀ are input to an addition circuit 11 and a subtraction circuit 12, respectively. The output V ₁₁ of the adder circuit 11 is V ₁₁ =αIN/M+αIM−N/M=αI, and the output V ₁₂ of the subtractor circuit 12 is V ₁₂ =αIN/M−αIM−N/M=αI・(2N/ M-1
) becomes.

Next, these two voltage outputs V ₁₁ and V ₁₂ are divided by the division circuit 13 to become V ₁₃ .

V ₁₃ = V ₁₂ / V ₁₁ = αI (2N/M-1) / αI = 2N/M-1 The output voltage V 13 of this divider circuit ₁₃ depends on the position of the photodetector element where the laser beam is incident. voltage. From this output voltage V ₁₃ , a direction discrimination display circuit 14 consisting of a level comparator and a display element,
15, 16, and 17 indicate that the laser beam has been irradiated, and also display the direction of arrival of the laser beam.

(Problem to be Solved by the Invention) Therefore, in order to display the arrival direction of the laser beam in detail, the direction discrimination display circuits 14, 15, 16,
As the number of 17 increases, the number of adjustment points increases, making adjustment difficult.

Another drawback is that the direction of arrival of the laser beam cannot be finely divided due to optical distortion of the condenser lens 2 and electrical distortion occurring in the electrical circuit such as variations in the current-voltage conversion ratio.

The present invention solves the above-mentioned drawbacks and provides a laser beam warning device that can easily and accurately detect the direction of arrival of laser beams.

(Means for Solving the Problems) The present invention arranges a plurality of photodetecting elements in an array, and combines these with a condensing lens to direct laser light to the array according to its incident angle. The light is focused on one of the photodetecting elements arranged in a shape, and the photocurrent output from the photodetecting element is divided into two outputs according to a division ratio unique to each photodetecting element.
Since the two outputs are converted into digital signals by the A/D conversion circuit and processed as digital signals, the direction determining circuit described above is not required, resulting in a configuration that does not require adjustment for determining the direction of arrival of the laser light.

In addition, correction is made for distortion of the linearity of the electric signal caused by variations in the circuit constants of the two current-voltage conversion circuits, and correction is made for optical distortion of the condensing lens, and the distribution ratio of the photocurrent output is calculated by calculation. Accordingly, the direction in which the irradiated laser light has come is displayed with higher accuracy.

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention, in which a detection element array 3 in which a condensing lens 2 and a light detection element 4 are arranged in an array, impedance elements 6, 7, 8, and a current Voltage conversion circuit 9, 1
0, the discrimination circuit 18, and the logarithmic amplifier circuits 19 and 20.
, a two-channel A/D conversion circuit 21 , and an arithmetic display circuit 22 .

The calculation display circuit 22 includes a correction value for optical distortion of the condenser lens 2, a correction value for distortion due to variation in electric circuit constants such as variation in the current-voltage conversion ratio of the current-voltage conversion circuits 9 and 10, and a logarithmic amplifier circuit 19. A storage unit that stores correction values for the linearity of the input/output characteristics of No. 20, a calculation unit that performs correction calculations and calculations to determine the incident angle of the laser beam, and displays the incident angle of the laser beam determined by the calculation unit. It consists of a display section and a display section.

The photodetecting elements 4 and the like on the photodetecting element array 3 are connected by a single resistor or impedance elements 6, 7, and 8 composed of resistance, inductance, and capacitance, and connected to any of the photodetecting elements on the photodetecting element array 3. The photocurrent output generated when light is irradiated is divided into two parts according to a distribution ratio according to the position of the photodetector element irradiated with light.

The photocurrent output divided into two is supplied to two current-voltage conversion circuits 9 and 10, which convert the photocurrent into voltage. This voltage output is supplied to the discrimination circuit 18, which discriminates whether the light is a laser beam or not, and the A/D conversion circuit 2.
Sends a conversion timing signal to 1. Furthermore, the output voltages of the current-voltage conversion circuits 9 and 10 are
9 and 20, and is converted into a digital signal by a two-channel A/D conversion circuit 21, thereby allowing signal processing of the irradiated laser light over a wide range of intensity levels. The digital signal converted by the two-channel A/D conversion circuit 21 is converted into a linearity correction value of the input/output characteristic of the logarithmic amplifier circuit stored in advance, and current-voltage conversion by the current-voltage conversion circuits 9 and 10. After correction values for variations in circuit constants on the electric circuit, such as variations in rate, and correction values for optical distortion of the condenser lens 2, the two digital signals are used to calculate the value of the photodetector element irradiated with laser light. The direction in which the laser light has arrived is displayed by calculating the distribution ratio of the photocurrent output according to the position. This eliminates the need for adjustment for direction determination in the direction determination display circuit.

Now, if the laser beam 1 enters the condenser lens 2 at a certain incident angle θ, the condenser lens 2 directs the laser beam 1 to the condensing point 5 on the photodetector array 3.
The light is focused on. The photodetecting element 4 at this condensing point 5
outputs a photocurrent I depending on the intensity of the incident laser light.

Here, if the impedance of the impedance elements 6, 7, 8 is Z, the number is M, and the current-voltage conversion rate of the current-voltage conversion circuits 9, 10 is α, then the logarithmic amplifier circuit 19 passing through the current-voltage conversion circuits 9, 10 ,2
0 outputs are V ₁₉ and V ₂₀ respectively, V ₁₉ = log (αINZ/MZ) = log (αIN/M) V ₂₀ = log (αI (M-N)Z/MZ) = log (αIM-N /
M) becomes. N is the photodetecting element 4 on which the laser beam is incident;
This is the position of These two outputs V ₁₉ and V ₂₀ are converted into digital signals by a two-channel A/D conversion circuit 21, and the digital signals are sent to an arithmetic display circuit 22.

The calculation display circuit 22 has two channels of A/D.
The linearity of the input/output characteristics of the logarithmic amplifier circuits 19 and 20 is corrected for the digital signal from the conversion circuit 21, and an exponent is calculated. Next, correction is made for variations in electric circuit constants such as variations in current-voltage conversion ratio. Letting the two digital signals at this time be V _D1 and V _D2 , respectively, V _D1 = αIN/MV _D2 = αIM-N/M. The variables in these two equations are after performing correction calculations.

By performing the following calculation from these two digital signals, the incident angle θ at the laser tip can be determined.

V _S =V _D1 -V _D2 /V _D1 +V _D2 =2N/M-1 θ=k・V _S (k is a proportionality constant) Finally, add correction for the optical distortion of the condenser lens 2 to this calculation result. This makes it possible to easily determine the direction of arrival of the laser beam with greater precision and without making adjustments to determine the direction of arrival.

Along with this, it is also possible to know the intensity level of the irradiated laser beam.

(Effects of the Invention) As explained above, the present invention combines a plurality of photodetecting elements arranged in an array with a condensing lens, and adjusts the number of photodetecting elements in the photodetecting element array according to the incident angle of laser light. Laser light is focused on one photodetecting element, and the photocurrent output from the photodetecting element is divided into two outputs according to the distribution ratio specific to each photodetecting element, and these two outputs are divided into A The photocurrent output is distributed after converting it into a digital signal using a /D conversion circuit and correcting the distortion in the linearity of the electrical signal caused by variations in the circuit constants of the electrical circuit, as well as the optical distortion of the condensing lens. By calculating the ratio, regardless of the incident intensity of the laser beam, the direction in which the laser beam has arrived can be easily determined without making adjustments to determine the direction of arrival with greater accuracy, as well as the effect of the irradiated laser beam. It also has the effect of knowing the intensity level of the object.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
FIG. 2 is a block diagram showing a conventional laser beam warning device. 1...Laser light, 2...Condenser lens, 3...Photodetection element array, 4...Photodetection element, 5...Focusing point, 6, 7, 8...Impedance element, 9, 1
0... Current voltage conversion circuit, 11... Addition circuit, 1
2... Subtraction circuit, 13... Division circuit, 14,1
5, 16, 17... Discrimination display circuit, 18... Discrimination circuit, 19, 20... Logarithmic amplifier circuit, 21... 2
Channel A/D conversion circuit, 22...Arithmetic display circuit.

Claims (1)

[Claims] 1. A laser light detection unit that detects laser light incident on the condenser lens by arranging a condenser lens and a photodetection element array in which a plurality of photodetection elements are arranged in an array at the focal position of the condenser lens; , comprising means for dividing the photocurrent output from each photodetecting element of the photodetecting element array into two current outputs according to a distribution ratio specific to each photodetecting element, and the divided two current outputs is converted into a voltage, logarithmically amplified, and converted into a digital signal by an A/D conversion circuit.The linearity of the electrical signal that occurs due to variations in circuit constants when converting the two divided current outputs into voltage is By digitally correcting the distortion of A laser light warning device that displays direction.