KR20100124001A - Apparatus and method for calculating phase of laser in laser scanner, and laser scanner with the said apparatus - Google Patents

Abstract

PURPOSE: A laser scanner for calculating the phase of an optical signal, a method thereof and a laser scanner for obtaining high amplification rate in the laser scanner are provided to calculate the phase of the optical signal through the multi layer phase modulation. CONSTITUTION: A second signal generating unit comprises a second phase demodulating unit(163) and a second intermediate frequency signal generating unit(164). The second signal generating unit generates second intermediate frequency signal in which the phase of the first intermediate frequency signal is demodulated. A phase calculation unit(166) calculates the phase of the reflective signal by using the second reference signal having intermediate frequency factor.

Description

Apparatus and method for calculating phase of laser in laser scanner, and laser scanner with the said apparatus}

The present invention relates to an apparatus for calculating the phase of an optical signal in a laser scanner, a method thereof, and a laser scanner having the apparatus. More particularly, the present invention relates to an apparatus and method for calculating a phase of an optical signal through demodulation using an intermediate frequency signal in a laser scanner, and a laser scanner having the apparatus.

A laser scanner is a surveying device that scans a myriad of laser beams at close intervals on the surface of an object to obtain three-dimensional coordinate values in the form of points. Such laser scanners have the advantage of being able to measure large areas with good resolution. Therefore, laser scanners are installed in three-dimensional shape measurement fields, such as visualizing and modeling three-dimensional point coordinates, construction fields, such as manufacturing drawings using three-dimensional point coordinates, factory automation fields, roads installed in moving vehicles or roads. It is widely used throughout the transportation industry, such as acquiring surrounding information, robot navigation, driverless car, shipbuilding port industry, and its application market is expanding.

Conventional methods for calculating distance using a laser scanner include a flight time method and a distance calculation method using a phase difference of an optical signal. The former (flight time method) is a method of calculating the distance by counting the time the light has traveled in the number of pulses, and is mainly used for measuring long distances for military purposes. However, this method has a problem such that a pulse counter of 30 GHz or more is required to obtain a resolution within 10 mm.

The latter (distance calculation method using the phase difference of the optical signal) is a method of calculating the distance through the phase difference between the reference signal and the reflected signal reflected from the observation object. This method is classified into a frequency modulation / demodulation method for obtaining distance information through frequency and an amplitude modulation / phase demodulation method for obtaining distance information through phase angle according to a modulation method of a light source.

The frequency modulation / demodulation method is suitable for short-range measurements and has the advantage of achieving better resolution than the amplitude modulation / phase demodulation method. However, the frequency modulation / demodulation method requires an expensive light source to vary the frequency, which is disadvantageous for long distance measurement.

On the other hand, the amplitude modulation / phase demodulation method is suitable for long distance measurement, such as obtaining a resolution in mm from a measurement distance of several m to several tens of meters. However, in the conventional amplitude modulation / phase demodulation method, the light source must be excited using a high frequency signal in order to obtain high resolution. However, it has been very difficult to amplify a high frequency signal during the modulation / demodulation signal processing because the signal amplification rate is limited by the frequency bandwidth.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an apparatus and method for calculating the phase of an optical signal through multi-stage phase demodulation using an intermediate frequency signal in a laser scanner, and a laser scanner including the apparatus. The purpose.

The present invention has been made to achieve the above object, a first signal for generating a first intermediate frequency signal of the phase demodulated the reflected signal reflected from the observation object using a first reference signal having a predetermined demodulation frequency component Generation unit; A second signal generator configured to generate a second intermediate frequency signal obtained by phase demodulating the first intermediate frequency signal using a phase shift signal obtained by phase shifting the first reference signal; And a phase calculator configured to calculate a phase of the reflected signal using a second reference signal having an intermediate frequency component extracted from the first intermediate frequency signal and a final intermediate frequency signal amplified by the second intermediate frequency signal. A phase calculation device is provided.

Preferably, the phase calculation device further comprises a final signal generator for generating the final intermediate frequency signal by adding the first intermediate frequency signal to the second intermediate frequency signal.

Preferably, the phase calculator comprises a reference output generation module for generating a reference output that is a product of the second reference signal and the final intermediate frequency signal; A comparison output generation module for generating a comparison output that is a product of the phase shifted second reference signal and the final intermediate frequency signal; And a phase calculation module for calculating a phase of the reflected signal which is a ratio value between the reference output and the comparison output. More preferably, the reference output generation module or the comparison output generation module includes a filtering module for passing a signal having a frequency component smaller than the intermediate frequency component of the generated output.

Preferably, the first signal generator comprises: a phase demodulator for phase demodulating the reflected signal using the first reference signal; And a first intermediate frequency signal generator for filtering the phase demodulated signal to generate the first intermediate frequency signal, or the second signal generator phase demodulating the first intermediate frequency signal using the phase shift signal. A phase demodulator; And a second intermediate frequency signal generator for filtering the phase demodulated signal to generate the second intermediate frequency signal. More preferably, the first intermediate frequency signal generator generates the first intermediate frequency signal having a difference value between a frequency component of the reflected signal and a frequency component of the first reference signal as a frequency component. Still more preferably, the first intermediate frequency signal generator includes a filtering unit for passing a signal greater than a frequency component of the first intermediate frequency signal and smaller than a frequency component of the reflected signal among the phase demodulated signals.

Preferably, the second signal generator uses a signal obtained by phase shifting the reference demodulation signal by 90 degrees with the phase shift signal.

Preferably, the second signal generator generates the second intermediate frequency signal by phase shifting the first reference signal at least twice.

In addition, the present invention comprises the steps of (a) generating a first intermediate frequency signal demodulated demodulated from the reflection signal reflected from the observation object using a first reference signal having a predetermined demodulation frequency component; (b) generating a second intermediate frequency signal obtained by phase demodulating the first intermediate frequency signal using a phase shift signal obtained by phase shifting the first reference signal; And (c) calculating a phase of the reflected signal using a second reference signal having an intermediate frequency component extracted from the first intermediate frequency signal and a final intermediate frequency signal amplified by the second intermediate frequency signal. It provides a phase calculation method characterized in that.

Advantageously, said intermediate step of steps (b) and (c) includes adding said first intermediate frequency signal to said second intermediate frequency signal to produce said final intermediate frequency signal.

Advantageously, step (c) comprises: (ca) generating a reference output that is a product of said second reference signal and said final intermediate frequency signal; (cb) generating a comparison output that is a product of the phase shifted second reference signal and the final intermediate frequency signal; And (cc) calculating a phase of the reflected signal that is a ratio value between the reference output and the comparison output. More preferably, step (ca) or step (cb) passes the signal having a frequency component smaller than the intermediate frequency component of the generated output to generate the reference output or the comparison output.

Advantageously, step (a) comprises: (aa) phase demodulating said reflected signal using said first reference signal; And (ab) filtering the phase demodulated signal to generate the first intermediate frequency signal, or (b) step (ba) phase the first intermediate frequency signal using the phase shift signal. Demodulating; And (bb) filtering the phase demodulated signal to produce the second intermediate frequency signal. More preferably, the step (ab) generates the first intermediate frequency signal having the difference between the frequency component of the reflected signal and the frequency component of the first reference signal as a frequency component, or the phase demodulated signal. The first intermediate frequency signal is generated by passing a signal larger than a frequency component of the first intermediate frequency signal and smaller than a frequency component of the reflected signal.

Advantageously, step (b) generates said second intermediate frequency signal by phase shifting said first reference signal at least twice.

In addition, the present invention includes a light generating unit for generating a laser light; A light direction adjusting unit which adjusts the generated light into parallel light; An optical transmitter for outputting the parallel light to an object; A light receiver configured to receive light reflected from the object; A light detector detecting the received light; And a first signal generator configured to generate a first intermediate frequency signal obtained by phase demodulating the signal based on the detected light using a first reference signal having a predetermined demodulation frequency component, and phase shifting the first reference signal. A second signal generator for generating a second intermediate frequency signal obtained by phase demodulating the first intermediate frequency signal using the phase shift signal; and a second reference signal having an intermediate frequency component extracted from the first intermediate frequency signal. And a phase calculator including a phase calculator configured to calculate a phase of the reflected signal by using a final intermediate frequency signal amplified by the second intermediate frequency signal.

Preferably, the laser scanner further comprises a scanner head for changing the firing angle of the light output to the object, and calculates the distance to one side of the object using the light whose firing angle is changed by the scanner head.

According to the present invention, the following effects can be obtained by calculating the phase of an optical signal through multi-phase demodulation using an intermediate frequency signal in a laser scanner. First, by using an intermediate frequency signal, a very high amplification factor can be obtained during modulation / demodulation signal processing and low frequency noise can be reduced. Second, by performing a multi-step demodulation process, signal to noise ratio (SNR) can be improved and the resolution of the scanner can be improved.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

1 is a block diagram schematically showing a laser scanner according to a preferred embodiment of the present invention. The following description refers to FIG. 1.

According to FIG. 1, the laser scanner 100 according to an exemplary embodiment of the present invention includes a light generator 110, an optical modulator 120, an optical transmitter 130, an optical receiver 140, and an optical detector 150. And a phase calculation device 160.

The laser scanner 100 according to the present embodiment is a laser scanner using an amplitude modulation / phase demodulation method. The laser scanner 100 calculates the distance for each laser beam to visualize three-dimensional point coordinates for the observation object and to model the observation object.

Conventional laser scanners using amplitude modulation / phase demodulation methods use high frequency signals to excite a light source to achieve high resolution. However, it is very difficult to amplify a high frequency signal during the modulation / demodulation signal processing because the amplification rate of the signal is limited by the frequency bandwidth. Therefore, the laser scanner 100 according to the present embodiment calculates the phase of the optical signal through multi-step demodulation using the intermediate frequency signal. In the laser scanner 100, such a function is performed by the phase calculation device 160, and a detailed description thereof will be described later.

The light generator 110 performs a function of generating light. In this embodiment, the modulated signal is electrically generated and then applied to the light generator 110 so that the light generator 110 generates light. The light generator 110 includes a laser diode 111 for generating a laser beam. The light generated by the light generator 110 is transmitted to the light transmitter 130 as a reference signal.

The optical transmitter 130 transmits the generated light to an external observation object. In the present embodiment, the optical transmitter 130 includes a scanner head 131 that adjusts the angle of the modulated light so that the specification of the observation target to be scanned can be densely obtained.

The scanner head portion 131 includes one stationary scanner head or one rotary scanner head. The fixed scanner head makes it possible to obtain a fixed subject specification at high speed by scanning the circumference of the fixed subject. However, since the scanner head is fixed, there is a problem in that the specifications of the surrounding objects cannot be obtained densely while moving, for example, in a condition around a road. Similarly, the rotary scanner head has a problem that it is difficult to densely obtain the specifications of surrounding objects at high speed. In this embodiment, it is preferable that the scanner head portion 131 be a multi-head type such as a plurality of fixed scanner heads, a plurality of rotary scanner heads, at least one fixed scanner head, and at least one rotary scanner head.

Meanwhile, the light direction controller 120 may be further included between the light generator 110 and the light transmitter 130. The light direction adjusting unit 120 adjusts the generated light emitted into parallel light. The light direction controller 120 may be implemented by, for example, a collimating lens.

The light receiver 140 performs a function of receiving the reflected light reflected from the observation object. The light receiving unit 140 further includes a light collecting unit 141 for condensing the received light. The condensing function of the condenser 141 can improve the resolution by increasing the opening angle of the light. The condenser 141 may be implemented as, for example, a condenser.

The light detector 150 detects the collected light. The light detector 150 may be implemented as, for example, a photo detector.

The phase calculating device 160 calculates a phase of an optical signal through multi-step demodulation using an intermediate frequency signal. This function of the phase calculation device 160 is performed in the phase demodulation step of the optical signal, it is possible to calculate the distance for each laser beam in accordance with the present embodiment, and to model the object to be observed in three-dimensional solid. Hereinafter, the phase calculation device 160 will be described in more detail.

2 is a block diagram schematically illustrating an apparatus for calculating a phase of an optical signal in a laser scanner according to a preferred embodiment of the present invention. The following description refers to FIG. 2.

According to FIG. 2, a device for calculating a phase of an optical signal in a laser scanner, that is, the phase calculating device 160 calculates a phase using an intermediate frequency component while multi-phase demodulating an optical signal obtained after being reflected from an object to be observed. . In the present embodiment, the phase calculator 160 may include the first phase demodulator 161, the first intermediate frequency signal generator 162, the second phase demodulator 163, and the second intermediate frequency signal generator 164. ), The final intermediate frequency signal generator 165 and the phase calculator 166.

The first phase demodulator 161 performs a function of demodulating the phase of the acquisition signal by multiplying the obtained optical signal by a reference demodulation signal having a predetermined demodulation frequency component. In the present embodiment, the predetermined demodulation frequency component has a component value of 19.95 MHz. However, the present invention is not necessarily limited thereto, and the predetermined demodulation frequency component may be arbitrarily selected by the user in some cases.

According to the amplitude modulation / phase demodulation signal processing method, the reference demodulation signal and the obtained optical signal are respectively represented by Equations 1 (a) and (b) below.

In Equation 1, V _ref is the reference demodulation signal, V _r is the amplitude of the reference demodulation signal, w _d is the frequency of the reference demodulation signal, V _d is the acquisition signal, V _sig is the amplitude of the acquisition signal, and w _sig is the acquisition signal. The frequency φ represents a phase value having distance information, and N (ξ) represents a noise component.

The first phase demodulator 161 demodulates the phase of the acquisition signal by multiplying (a) and (b) in Equation (1). The phase demodulated signal is expressed by Equation 2 below.

In Equation 2, V _i is a phase demodulated signal, w _i is w _sig -w _d as the intermediate frequency. In this embodiment, the intermediate frequency is 50 kHz. However, the intermediate frequency does not necessarily need to be limited thereto.

The first intermediate frequency signal generator 162 filters the phase demodulated signal to generate a first intermediate frequency signal. In the present embodiment, the first intermediate frequency signal generator 162 uses a low pass filter (LPF) to pass signals whose cut-off frequency is larger than the intermediate frequency and smaller than the frequency of the acquired optical signal. Accordingly, the first intermediate frequency signal extracted from the first intermediate frequency signal generator 162 is expressed by Equation 3 below. Equation 3 is to remove the second and third terms in the equation (2).

In Equation 3, v _i 'is the first intermediate frequency signal.

The second phase demodulator 163 demodulates the phase of the first intermediate frequency signal by multiplying the first intermediate frequency signal by the transition signal. The transition signal is a signal obtained by phase shifting the reference demodulation signal, and in this embodiment, the reference demodulation signal is shifted by 90 degrees.

The second intermediate frequency signal generator 164 filters the rephase demodulated signal through the second phase demodulator 163 to generate a second intermediate frequency signal. The second intermediate frequency signal is expressed by Equation 4 below.

In Equation 4 V _i '' is a second intermediate frequency signal.

In the present exemplary embodiment, a two-step phase demodulation process such as a first phase demodulator 161, a first intermediate frequency signal generator 162, a second phase demodulator 163, and a second intermediate frequency signal generator 164 is performed. To obtain an intermediate frequency signal. However, the present embodiment is not limited thereto, and it is also possible to obtain an intermediate frequency signal through three or more phase demodulation processes.

The final intermediate frequency signal generator 165 amplifies the second intermediate frequency signal to generate a final intermediate frequency signal. In this embodiment, the final intermediate frequency signal generator 165 adds the first intermediate frequency signal to the second intermediate frequency signal to obtain a final intermediate frequency signal. The final intermediate frequency signal is expressed by Equation 5 below.

In Equation 5, V _d 'is the final intermediate frequency signal.

By using the final intermediate frequency signal in this embodiment, the amplification factor can be effectively adjusted during the amplitude modulation / phase demodulation signal processing. This is because the final intermediate frequency signal transitions to the low frequency band (= 50 kHz) as it undergoes a multi-phase demodulation process. Accordingly, a high frequency signal can be easily amplified, a high amplification rate can be obtained, and a signal-to-noise ratio can be further improved than before because the signal is multiplied by a gain equal to the amplitude (Vr) of the reference demodulated signal regardless of noise. .

The phase calculator 166 calculates a phase using a reference signal having an intermediate frequency component and a final intermediate frequency signal. The phase calculation unit 166 calculates the phase as follows.

In a first step, an initial reference output is generated by multiplying a reference signal having an intermediate frequency component by a final intermediate frequency signal. In this embodiment, this function is the first reference output module (not shown). The initial reference output is shown in Equation 6 below.

In Equation 6, V _{i, out} is the initial reference output.

However, since the initial reference output includes a high frequency component having a frequency 2w _i , it is necessary to remove this component through filtering. In a second step, the final reference output module (not shown) passes a signal whose cut-off frequency is less than w _i . The final reference output output through the second step is expressed by Equation 7 below.

In Equation 7, V _{i, out} ′ is the final reference output.

In a third step, an initial comparison output module (not shown) multiplies the phase shifted reference signal by the final intermediate frequency signal to produce an initial comparison output. The phase shifted reference signal is a signal obtained by shifting the reference signal V _r 'sinw _i t by 90 °.

In a fourth step, the final comparison output module (not shown) filters the high frequency components to pass signals whose cut-off frequency is less than w _i . Accordingly, the final comparison output output from the final comparison output module is expressed by Equation 8 below.

In Equation 8, V _{i, out} '' is the final comparison output.

In a fifth step, the phase value calculation module (not shown) calculates the phase value from the ratio to the reference output of the comparison output. The phase value is calculated according to Equation 9 below.

In Equation 9, φ 'is a phase value.

In the demodulation process, as in Equations 7 and 8, the gains of V _r and V _r 'are multiplied only by the signal, thereby improving the signal-to-noise ratio, and the phase value obtained by Equation 9 also has a high signal-to-noise ratio. . Accordingly, in the present embodiment, an improvement in resolution of the laser scanner can be expected. Resolution in a laser scanner using an amplitude modulation / phase demodulation method can be obtained from Equation 10 below.

In Equation 10, δ d means resolution and δ φ means a phase value.

On the other hand, since the phase value? 'Has a final distance signal, it is also possible to obtain the distance from this to the laser beam-observing object. In this case, the multi-step demodulation process is expected to enable accurate distance measurement as signal-to-noise ratio and resolution are improved.

3 is a graph comparing a phase according to an existing amplitude modulation / phase demodulation method and a phase according to the present embodiment. 3A is a graph showing the noise level of the phase according to the conventional method when the distance from the laser scanner to the object to be observed is 1 m. And (b) is a graph showing the noise level of the phase according to the present embodiment when the distance from the laser scanner to the observation object is 1m. And, (c) is a graph showing the noise level of the phase according to the conventional method when the distance from the laser scanner to the observation object is 7.5m. And, (d) is a graph showing the noise level of the phase according to the present embodiment when the distance from the laser scanner to the observation object is 7.5m. As can be seen when comparing (b) and (d) with (a) and (c), respectively, the method according to the present embodiment can improve the signal-to-noise ratio and resolution than the conventional method.

Next, a method of calculating the phase of the optical signal in the laser scanner will be described. 4 is a flowchart illustrating a method of calculating a phase of an optical signal in a laser scanner according to a preferred embodiment of the present invention. The following description refers to FIG. 4.

First, the first phase demodulator 161 demodulates a phase of an acquisition signal by multiplying the obtained optical signal by a reference demodulation signal having a predetermined demodulation frequency component (S400).

Thereafter, the first intermediate frequency signal generator 162 filters the phase demodulated signal to generate a first intermediate frequency signal (S410). In this embodiment, the first intermediate frequency signal generator 162 uses a low pass filter (LPF) to pass signals having a cut-off frequency greater than the intermediate frequency and smaller than the frequency of the acquired optical signal. 1 Generate an intermediate frequency signal.

Thereafter, the second phase demodulator 163 demodulates the phase of the first intermediate frequency signal by multiplying the first intermediate frequency signal by the transition signal (S420). The transition signal is a signal obtained by phase shifting the reference demodulation signal, and in this embodiment, the reference demodulation signal is shifted by 90 degrees.

Thereafter, the second intermediate frequency signal generator 164 filters the rephase demodulated signal through the second phase demodulator 163 to generate a second intermediate frequency signal (S430).

Thereafter, the final intermediate frequency signal generator 165 amplifies the second intermediate frequency signal to generate a final intermediate frequency signal (S440). In this embodiment, the final intermediate frequency signal generator 165 adds the first intermediate frequency signal to the second intermediate frequency signal to obtain a final intermediate frequency signal.

Thereafter, the phase calculator 166 calculates a phase using the reference signal having the intermediate frequency component and the final intermediate frequency signal (S450). Since the method for calculating the phase by the phase calculator 166 has been described above with reference to FIG. 2, the description thereof is omitted here.

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. It will be possible. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

The present invention selects an appropriate intermediate frequency (50 kHz, 10 kHz) in the analog phase demodulation process, and has an advantage of enabling effective signal amplification and reducing noise effects through a multi-step demodulation process. In addition, more accurate distance measurement is possible by improving the signal-to-noise ratio and improving the resolution performance.

The present invention can be used throughout the industry where three-dimensional shape measurement is required. That is, the present invention can be widely used in various fields such as robot navigation, distance between cars, three-dimensional shape of mechanical parts, civil building surveying, crane height measurement in shipbuilding port, shape measurement for restoration of cultural property building.

1 is a block diagram schematically showing a laser scanner according to a preferred embodiment of the present invention.

2 is a block diagram schematically illustrating an apparatus for calculating a phase of an optical signal in a laser scanner according to a preferred embodiment of the present invention.

3 is a graph comparing a phase according to an existing amplitude modulation / phase demodulation method and a phase according to the present embodiment.

4 is a flowchart illustrating a method of calculating a phase of an optical signal in a laser scanner according to a preferred embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

100: laser scanner 110: light generating unit

111 laser diode 120 light modulator

130: light transmitting unit 131: scanner head

140: light receiving unit 141: light collecting unit

150: light detector 160: phase calculating device

161: first phase demodulator 162: first intermediate frequency signal generator

163: second phase demodulator 164: second intermediate frequency signal generator

165: final intermediate frequency signal generator 166: phase calculator

Claims (18)

A first signal generator for generating a first intermediate frequency signal obtained by phase demodulating a reflected signal reflected from an object to be observed using a first reference signal having a predetermined demodulation frequency component; A second signal generator configured to generate a second intermediate frequency signal obtained by phase demodulating the first intermediate frequency signal using a phase shift signal obtained by phase shifting the first reference signal; And A phase calculator for calculating a phase of the reflected signal using a second reference signal having an intermediate frequency component extracted from the first intermediate frequency signal and a final intermediate frequency signal amplified by the second intermediate frequency signal; Phase calculation device comprising a. The method of claim 1, The final signal generator for generating the final intermediate frequency signal by adding the first intermediate frequency signal to the second intermediate frequency signal Phase calculation device further comprising. The method of claim 1, The phase calculation unit, A reference output generation module for generating a reference output that is a product of the second reference signal and the final intermediate frequency signal; A comparison output generation module for generating a comparison output that is a product of the phase shifted second reference signal and the final intermediate frequency signal; And A phase calculation module for calculating a phase of the reflected signal that is a ratio value between the reference output and the comparison output Phase calculation device comprising a. The method of claim 1, The first signal generator, A phase demodulator configured to phase demodulate the reflected signal using the first reference signal; And A first intermediate frequency signal generator configured to filter the phase demodulated signal to generate the first intermediate frequency signal Contains; The second signal generator, A phase demodulator for phase demodulating the first intermediate frequency signal using the phase shift signal; And A second intermediate frequency signal generator configured to filter the phase demodulated signal to generate the second intermediate frequency signal Phase calculation device comprising a. The method of claim 4, wherein And the first intermediate frequency signal generator generates the first intermediate frequency signal having a difference value between a frequency component of the reflected signal and a frequency component of the first reference signal as a frequency component. The method of claim 5, And the first intermediate frequency signal generator comprises a filtering unit configured to pass a signal greater than a frequency component of the first intermediate frequency signal and smaller than a frequency component of the reflected signal among the phase demodulated signals. The method of claim 3, wherein The reference output generation module or the comparison output generation module includes a filtering module for passing a signal having a frequency component smaller than the intermediate frequency component among the generated outputs. The method of claim 1, And the second signal generator uses a signal obtained by phase shifting the reference demodulation signal by 90 degrees as the phase shift signal. The method of claim 1, And the second signal generator generates the second intermediate frequency signal by phase shifting the first reference signal at least twice. (a) generating a first intermediate frequency signal obtained by phase demodulating a reflected signal reflected from an object to be observed using a first reference signal having a predetermined demodulation frequency component; (b) generating a second intermediate frequency signal obtained by phase demodulating the first intermediate frequency signal using a phase shift signal obtained by phase shifting the first reference signal; And (c) calculating a phase of the reflected signal using a second reference signal having an intermediate frequency component extracted from the first intermediate frequency signal and a final intermediate frequency signal amplified by the second intermediate frequency signal; Phase calculation method comprising a. The method of claim 10, The intermediate step of the steps (b) and (c) includes the step of adding the first intermediate frequency signal to the second intermediate frequency signal to generate the final intermediate frequency signal. . The method of claim 10, In step (c), (ca) generating a reference output that is a product of the second reference signal and the final intermediate frequency signal; (cb) generating a comparison output that is a product of the phase shifted second reference signal and the final intermediate frequency signal; And (cc) calculating a phase of the reflected signal which is a ratio value between the reference output and the comparison output Phase calculation method comprising a. The method of claim 10, In step (a), (aa) phase demodulating the reflected signal using the first reference signal; And (ab) filtering the phase demodulated signal to produce the first intermediate frequency signal Contains; In step (b), (ba) phase demodulating the first intermediate frequency signal using the phase shift signal; And (bb) filtering the phase demodulated signal to produce the second intermediate frequency signal Phase calculation method comprising a. The method of claim 13, The step (ab) generates the first intermediate frequency signal having a difference value between the frequency component of the reflected signal and the frequency component of the first reference signal as a frequency component, or the first intermediate frequency signal among the phase demodulated signals. And passing the signal larger than the frequency component of the frequency signal and smaller than the frequency component of the reflected signal to generate the first intermediate frequency signal. 13. The method of claim 12, The step (ca) or step (cb) is a phase calculation method characterized in that for generating the reference output or the comparison output by passing a signal having a frequency component smaller than the intermediate frequency component of the generated output. The method of claim 10, And (b) generating the second intermediate frequency signal by phase shifting the first reference signal at least twice. A light generator for generating laser light; A light direction adjusting unit which adjusts the generated light into parallel light; An optical transmitter for outputting the parallel light to an object; A light receiver configured to receive light reflected from the object; A light detector detecting the received light; And A first signal generator which generates a first intermediate frequency signal obtained by phase demodulating the signal based on the detected light using a first reference signal having a predetermined demodulation frequency component, and phase shifting the first reference signal A second signal generator configured to generate a second intermediate frequency signal obtained by phase demodulating the first intermediate frequency signal using a phase shift signal, and a second reference signal having an intermediate frequency component extracted from the first intermediate frequency signal; And a phase calculator configured to calculate a phase of the reflected signal by using a final intermediate frequency signal amplified by the second intermediate frequency signal. Laser scanner comprising a. The method of claim 17, The laser scanner further comprises a scanner head for changing the firing angle of the light output to the object, the laser scanner, characterized in that for calculating the distance to one side of the object by using the light whose firing angle is changed by the scanner head .

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