JPH071201B2 - Light beam measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is used for measuring the characteristics of light beams such as laser light, LED light, and white light. The present invention relates to a light beam measuring device and a light beam measuring video camera capable of easily measuring intensity distribution and the like in real time.

[Conventional technology]

The following is a measuring device that has been conventionally used to measure the characteristics of a light beam such as a laser beam.

As shown in FIGS. 13 to 15, this device includes a photodetector b for receiving a light beam p projected from a light source device (laser projector etc.) a and photoelectrically converting it into an electric signal, and the photodetector b. Beam diameter r, r ′ by processing the electrical signal sent from
(See FIGS. 14 and 15) A controller d for digitally displaying data such as the above in a display window c, an oscilloscope f for displaying the light intensity distribution m of the beam cross section as an image, etc. Receiving laser light through a pinhole (or rotating slit) g provided in the center of
The light is made incident on the detector h.

[Problems to be Solved by the Invention]

However, the above-mentioned measuring device has the following problems.

[I] Since the dimension of the beam diameter is digitally displayed, a high level technique is required to grasp the cross-sectional shape of the beam.
That is, as shown in FIG. 14, when the center of the cross section of the beam is located at the central portion j of the detector h, the cross sectional shape of the beam can be grasped relatively easily, but as shown in FIG. When it is deviated from the portion j, the measurement becomes a fumbling state, and particularly when the beam cross section is not circular but is elliptical, the measurement becomes almost impossible.

[Ii] When the light intensity of the beam is large, the intensity distribution (Gaussian distribution) deviates from the screen of the oscilloscope, making it difficult to measure the intensity distribution. Also, when the beam diameter is small, the image becomes small and the measured value becomes small. Be inaccurate.

[Iii] As a result of the above, the object of measurement is a light beam whose beam diameter and beam intensity are in a certain range, the shape of the cross section is predicted, and the optical axis k is adjusted almost accurately. Being limited, it is far from being used as an auxiliary means for assembling and adjusting the light source device.

In view of the above problems, the present invention can measure the characteristics of a light beam easily and accurately in real time regardless of the diameter and intensity of the light beam, and as a result, assembling various light source devices in a production line. It is a technical object to provide a light beam measuring device and a measuring video camera that can be used for adjustment and inspection, and can also be widely used for observing and measuring the characteristics of various light source devices at the experimental development level.

[Means for Solving the Problems]

In order to solve the above problems, the present invention has the following means.

A light beam measuring device comprising a video camera, a monitor TV, and an oscilloscope, wherein the monitor TV displays the cross-sectional shape of the light beam, and the oscilloscope displays the optical power distribution as an image. A video camera that detects the light beam with a cursor, and a cursor generator that displays a linear cursor on the screen of the monitor TV so that it can move freely and sends the video signal projected at the same location as the displayed cursor to the oscilloscope. An optical beam measuring device, characterized in that the video camera is mounted movably on an optical bench, facing the light source device.

[Action]

[I] Since the light beam to be measured is detected using the video camera and the cross section of the beam is displayed on the monitor television as an image, the cross-sectional shape of the beam can be easily observed in real time.

[Ii] Since the cursor is generated at a desired timing,
A cursor can be freely generated on the screen of a monitor TV. Therefore, by generating a cursor at the center of the beam cross section, the beam peak intensity, intensity distribution, beam diameter, etc. can be displayed on an oscilloscope image, and the beam characteristics can be measured reliably and in real time. .

[Iii] By providing an optical bench and changing the distance between the light source device and the video camera, the minimum sectional position (focal length) of the beam and the divergence angle of the beam can be measured.

[Iv] Since an optical filter of the video camera is provided with a neutral density filter and a magnifying lens if necessary, accurate measurement can be performed regardless of the light intensity and the beam diameter of the beam.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. First
1 to 12 show an embodiment of the present invention. This apparatus is a two-dimensional CCD type video camera 1, a black and white monitor television 2, a cursor generator 3, and a trigger synchronization type oscilloscope (so-called. Synchroscope) 4,
The video camera 1 and the laser projector 5 are composed of an optical bench 6 and the like which are supported so as to be movable relative to each other. The video camera 1 is mounted on a support base 8 through a platform 7 so that the video camera 1 can be finely moved vertically and horizontally. It is supported. In the figure, 9
Is a power source for a video camera, and 10 is a power source for a laser.

The video camera 1 comprises an image pickup device 12 and an optical device 13 attached to the front side of the image pickup device 12, and the optical device 13 is a transparent scale arranged at the tip as shown in FIGS. 2 and 3. A plate 14 (one graduation has an interval of 10 μm, for example), a required number (two in the figure) of a neutral density filter 15, an imaging lens 16 and the like. The neutral density filter 15 includes the graduation plate 14 and lenses. It is at an intermediate position of 16 and is detachably attached to the lens barrel 11. In addition, to increase the resolution of the image if necessary,
A magnifying lens 17 is placed at the base of the optical device 13 (see Figure 4). The image pickup device 12 is composed of a CCD type optical sensor 18, an image transmitting unit 19 for sequentially transmitting the electric charges accumulated in the optical sensor 18 as a video signal, and the like.

The cursor generator 3 movably displays a linear cursor 22 (see FIG. 6 to FIG. 8) on the screen 20 of the monitor TV 2, and at the same time, the video signal projected at the same place as the cursor 22 is oscilloscope-displayed. 4 serves as an image display, and its configuration is as shown in the block diagram of FIG.

Hereinafter, with reference to the drawings, the cursor generation device 3 will be described.
Receives the video signal 23 sent from the video camera 1 and receives two types of pulse signals, that is, a horizontal synchronizing signal 24 which is generated each time the horizontal scanning of the screen of the monitor TV is completed (every scanning line), A sync signal separation circuit 26 which separates and outputs a vertical sync signal 25 generated every time the vertical scanning of the screen is completed (one screen at a time)
And a binary counter 27 for counting the number of inputs of the horizontal synchronization signal 24 as a binary coded decimal number by using the horizontal synchronization signal 24 as a clock input and the vertical synchronization signal 25 as a reset input, and an output signal of the binary counter 27. 28
Is compared with an output signal 30 of a micro computer 29 described later, and a comparison / match detection circuit 33 that outputs a cursor signal 32 only when the two output signals 28 and 30 match, the cursor signal 32 and the video signal 23. And a video and video signal mixing circuit 34 for mixing and sending them to the monitor TV 2.

The microcomputer 29 stores a memory 31 for storing each scanning line of the monitor TV screen 20 (512 lines in the case of interlace, 256 lines in the case of non-interlace) as separate addresses, and a desired one from the memories 31. A panel switch 41 arranged on the front surface of the panel of the cursor generator, which includes a CPU 36 for extracting one scanning line and a binary register 37 for temporarily storing one extracted scanning line.
Is operated so that a desired scan line is extracted.

The cursor signal 32 is separately input to the trigger input terminal 39 of the oscilloscope 4 via the signal cable 38.

Since the cursor generator 3 is constructed as described above, the cursor 22 and the cross section 46 of the light beam are displayed on the screen 20 of the monitor television during the measurement as shown in FIGS. 7 and 8. Further, on the screen 40 of the oscilloscope, a video signal corresponding to the beam crossing where the cursor 22 crosses on the screen 20 of the monitor TV is displayed as a Gaussian distribution (light intensity distribution) 42 (see FIG. 10). .

As described above, the oscilloscope 4 is of a trigger synchronization type and is usually a commercially available product called a synchroscope. However, in order to easily directly read the beam diameter from the Gaussian distribution 42 displayed on the screen 40, The peak intensity is 100% (the position of 100% is 5c from the time axis 43, for example.
50m of this peak intensity
A scale corresponding to (half value), 36.8% (1 / e) and 13.5% (1 / e ² ) may be displayed on the screen 41.

Next, the handling procedure and operation of this device will be described. Before measurement, adjust the optical device 13 according to the following procedure,
Performs scale conversion to obtain measured values.

[I] When the power switch of each component is turned on and the panel switch 41 of the cursor generator 3 is operated, the scale of the scale 14 is displayed on the screen 20 of the monitor TV as shown in FIG.
44 and cursor 22 are displayed.

[Ii] The focus of the optical device 13 is adjusted. That is, when the front and rear portions of the lens barrel 11 are moved relative to each other at the joint 21 in the front and rear direction, the scale 44 of the scale plate 14 shown in FIG. 6 is clearly displayed.

[Iii] As shown in FIG. 7, the cursor 22 is moved on the screen 20 and aligned with the scale 44 of the scale plate 14. Here, when the oscilloscope 4 is operated, as shown in FIG. 9, the modulation waveform of the scale 44 on the scale plate near the time axis 43 of the oscilloscope.
Since 45 appears at regular intervals, the scale conversion is completed when the number of scales on the time axis 43 included in one wavelength λ of the modulation waveform 45 is read. When measuring a light beam having a small diameter, an optical device 13a (see FIG. 4) equipped with a magnifying lens 17 is used.

[Iv] The preparation for measurement is completed by the above operation. When the projector 5 is driven to project laser light onto the scale plate 14 of the video camera 1, a beam cross section 46 appears on the screen 20 of the monitor TV 2. (See FIG. 7).

[V] Here, as shown in FIG. 8, when the cursor 22 is moved so as to cross the center 47 of the beam cross section 46, the Gaussian distribution 42 in the cross section corresponding to the cursor 22 becomes Since the image is displayed as shown in the figure, the beam diameter is read on the scale of the time axis 43.

At this time, when the peak of the Gaussian distribution 42 is missing due to the saturation phenomenon as shown in FIG. 11, the optical device 13 is equipped with an appropriate number of the neutral density filters 15 to attenuate the light, and the peak is 100.
Make it come to% (see virtual line).

If the peak 48 of the Gaussian distribution 42 does not reach the level of 100% peak intensity as shown in Fig. 12, operate the knob (not shown) for vertical sensitivity switching on the oscilloscope to find the peak 48. Move the image upwards to reach 100% level (see phantom line).

By the above measurement operation, the cross-sectional shape, the beam diameter, the deflection degree of the optical axis, and the light intensity distribution of the light beam having a wavelength of 400 nm to 1200 nm can be measured easily, accurately, and in real time.

Further, when measuring the minimum cross-sectional position and divergence angle of the beam, the video camera 1 is appropriately moved along the optical bench 6 (arrow n), and the beam diameter is measured at each moving position.
The measured values obtained are compared with one another.

It should be noted that the present invention is not limited to the above-described embodiments, and for example, the image pickup device of the video camera may use another system instead of the CCD system, and other gist of the present invention. It goes without saying that various changes can be made without departing from the scope.

〔The invention's effect〕

As described above, the present invention exhibits the following excellent effects.

[I] Since the light beam to be measured is detected using the video camera and the cross section of the beam is displayed on the monitor television as an image, the cross-sectional shape of the beam can be easily observed in real time.

[Ii] Since the cursor is generated at the desired timing,
A cursor can be freely generated on the screen of a monitor TV. Therefore, by generating a cursor at the center of the beam cross section, the beam peak intensity, intensity distribution, beam diameter, etc. can be displayed on an oscilloscope image, and the beam characteristics can be measured reliably and in real time. .

[Iii] Since an optical filter of the video camera is provided with a neutral density filter and a magnifying lens if necessary, accurate measurement can be performed regardless of the light intensity and the beam diameter of the beam.

[Iv] By providing an optical bench and changing the optical distance between the light source device and the video camera, the minimum sectional position (focal length) of the light beam and the divergence angle of the beam can be measured.

[V] As a result of the above [i] to [iii], by using this device, the suitability of assembly and adjustment of various light source devices in the production line, and the characteristics of various light source devices at the experimental development level can be determined. It can be easily observed and measured.

[Brief description of drawings]

1 to 12 show an embodiment of the present invention, FIG. 1 is an explanatory view showing the overall arrangement, FIG. 2 is a sectional side view of an optical device, and FIG. 3 is III- in FIG. FIG. 4 is a sectional side view of another optical device, FIG. 5 is a block diagram showing the configuration of the cursor generating device, and FIGS. 6 to 8 are all on the monitor TV screen. FIGS. 9 to 12 are explanatory diagrams of the images displayed, and FIGS. 13 to 15 are explanatory diagrams of the images displayed on the oscilloscope screen.
The figure shows a conventional device, FIG. 13 is an explanatory view showing the overall arrangement, and FIGS. 14 and 15 are explanatory views of a cross section of a light beam incident on a detector. In the figure, 1 ... Video camera, 2 ... Monitor TV, 3 ... Cursor generator, 4 ... Oscilloscope, 5 ... Laser projector, 6 ... Optical bench, 12 ... Imaging device, 13 ... Optical device, 14 ... Scale plate, 15 ... darkening filter 16 ... imaging lens, 17 ... magnifying lens 18 ... optical sensor 20 ... monitor TV electronic screen 22 ... cursor 40 ... oscilloscope electronic screen

Claims (1)

[Claims] 1. A light beam measuring device comprising a video camera, a monitor TV, and an oscilloscope, wherein the monitor TV displays the cross-sectional shape of the light beam and the optical power distribution on the oscilloscope. A video camera that detects the light beam through the scale plate and a linear cursor are movably displayed on the screen of the monitor TV, and the video signal projected at the same position as the displayed cursor is sent to the oscilloscope. A light beam measuring device, wherein the video camera is mounted on an optical bench so as to be movable relative to the light source device.