JPH08278220A - Measuring apparatus of light beam shape - Google Patents

Abstract

PURPOSE: To obtain a measuring apparatus which eliminates a blooming phenomenon between adjacent elements when a light beam shape is measured by using a solid-state image sensing device and which can perform a measurement with high accuracy. CONSTITUTION: A sensor part 2 is constituted of a solid-state image sensing device 11 and of a shutter mechanism 12. A plurality of light receiving elements at the solid-state image sensing device 11 are operated selectively and sequentially by the shutter mechanism 12 driven by a controller 3 so as to obtain a light receiving signal. On the basis of the signal, a light beam shape is recognized by a signal processing means, signals from the adjacent light receiving elements can be acquired so as to be separated in terms of time, a blooming phenomenon between the adjacent light receiving elements is avoided, and the light beam shape can be measured with high accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a sectional shape of a light beam such as a laser beam for measuring lens performance, and more particularly to a measuring apparatus using a fine photosensor array.

[0002]

2. Description of the Related Art In order to measure whether or not an optical lens is manufactured as designed, the performance of the lens is measured. Measuring the beam shape is performed. As a method of measuring such a beam shape, a method of using a solid-state image sensor in which minute light receiving elements are arranged has been conventionally proposed. For example, JP-A-5
According to Japanese Patent Laid-Open No. 5-74407, a solid-state image sensor array arranged at a pitch smaller than the diameter of the light beam is irradiated with the light beam, and the distribution of output values of the respective solid-state image sensors is measured to obtain a cross section of the light beam. A method has been proposed in which the light intensity distribution in the direction is detected and the light beam shape is measured from this.

[0003]

However, in the solid-state image sensor array, when strong light is incident on one solid-state image sensor, the charges generated in the solid-state image sensor move to the adjacent solid-state image sensor. Since a so-called blooming phenomenon that affects the output of the element occurs, the output value of each solid-state imaging element is not necessarily proportional to the light intensity distribution of the light beam, and it is difficult to perform high-precision measurement. There is a problem.

[0004]

An object of the present invention is to enable high precision measurement by eliminating the influence between adjacent elements even when measuring the shape of a light beam using such a solid-state image pickup element. An object of the present invention is to provide a light beam shape measuring device.

[0005]

A light beam shape measuring apparatus according to the present invention includes a sensor section having a plurality of light receiving elements for receiving a light beam to be measured and outputting a signal corresponding to the light intensity, and A driving unit that drives the sensor unit to selectively and sequentially operate the light receiving elements, and a signal processing unit that processes a signal output from each of the light receiving elements and recognizes a light beam shape are provided.

Here, the sensor section includes, for example, a one-dimensional solid-state image pickup element in which a plurality of light-receiving elements are arranged in a dimension longer than a light beam diameter, and the plurality of light-receiving elements located in front of the solid-state image pickup element. And a shutter mechanism capable of individually blocking light. Alternatively, a two-dimensional solid-state image pickup device in which a plurality of light receiving elements are arranged in vertical and horizontal dimensions larger than the light beam diameter,
The shutter mechanism is located on the front side of the solid-state imaging device and can individually shield the plurality of light-receiving elements.

Further, the shutter mechanism is composed of, for example, a liquid crystal device, and a plurality of transparent electrodes respectively corresponding to a plurality of light receiving elements are formed in an array, and the transparent electrodes are selectively and sequentially energized. It is composed. Alternatively, the light-shielding plate is formed by arranging light-transmitting windows in an array, and the light-shielding plate can be moved on a plane perpendicular to the axial direction of the light beam in units of the arrangement pitch of the light-receiving elements.

[0008]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 (a) is a perspective view showing a configuration of a first embodiment of the present invention, and FIG. 1 (b) is a perspective view in which a main part thereof is disassembled into parts. In the figure, LB is a laser beam emitted from a laser light source (not shown) and condensed, and particularly indicates the vicinity of the laser waist where the beam system is narrowed. Here, it is assumed that the laser beam is in a linearly polarized state in a direction parallel to the Z axis. Reference numeral 1 denotes a light beam shape measuring device according to the present invention. Basically, a sensor unit 2 including a one-dimensional solid-state image pickup device 11 as a photosensor array and a shutter mechanism 12, and a sensor unit 2 are driven. , And a control unit 3 that measures the laser beam shape based on the light intensity detected by the sensor unit 2.

The sensor section 2 is constructed on a slider 14 which is movable on a guide rail 13 extending parallel to the optical axis of the laser beam LB, and a post 15 is erected vertically upward on the slider 14. A sensor holder 16 is supported on the upper end of the boss 15 so that its rotational position can be changed within a plane perpendicular to the laser beam LB. The one-dimensional solid-state image pickup device 11 and the shutter mechanism 12 of the sensor unit 2 are integrally provided on the sensor holder 16.

The one-dimensional solid-state image pickup device 11 of the sensor section 2
The shutter mechanism 12 is mainly composed of a liquid crystal 21 as shown in FIGS. 2 (a) and 2 (b), in which a front view and a side sectional view are shown together, and a transparent electrode 22 is provided on each of the front and back surfaces of the liquid crystal. , 23 are arranged. That is, the plurality of transparent electrodes 22 on the front surface are formed in a shape and size corresponding to the element array of the light receiving elements of the one-dimensional solid-state imaging device 11, and the transparent electrodes 2 on the rear surface are formed.
3 are formed in a continuous shape and size over the area of the element array, and are arranged so as to face each other with the liquid crystal 21 in between. The transparent electrode 23 on the back surface is commonly connected to the drive signal line c, but the transparent electrode 22 on the front surface is connected.
, Every other electrode 22a, 22b is connected to the drive signal lines a, b, respectively. Then, these transparent electrodes 22, 2
The liquid crystal 21 between 3 is arranged such that its molecules are continuously twisted and arranged by 90 degrees, and the polarization direction is rotated by 90 degrees. A polarizing plate 24 that transmits linearly polarized light in a direction parallel to the Y axis is provided on the back surface of the transparent electrode 23.
It is arranged so that the polarization direction after rotation by the liquid crystal 21 matches the polarization direction transmitted through the polarizing plate 24 under the condition that no voltage is applied between both transparent electrodes.

The control section 3 has a drive section 4 for driving the sensor section 2. The drive section 4 supplies a potential to each of the drive signal lines a to c as shown in FIG. Pair of drive circuits 31, 32 and each drive circuit 31, 3
It has a control circuit 33 for controlling the two. An output terminal of the control circuit 33 is connected to the one drive circuit 31, and an inverter 34 is connected to this output terminal so that its output side is connected to the other drive circuit 32. Further, the drive signal lines c are commonly connected. Therefore, when the signal “H” is output to the output terminal of the control circuit 33, the drive circuit 31 is driven and the potential is output between the drive signal lines a and c. As a result, a voltage is applied to the liquid crystal 21 in the region of the transparent electrode 22a, the light transmittance of this region is reduced, and this region is masked. When the signal “L” is output to the output terminal of the control circuit 33, the drive circuit 32 is driven to output a potential between the drive signal lines b and c, and the light transmittance of the other transparent electrode 22b region is increased. Be lowered.

The control unit 3 processes a signal output from the one-dimensional solid-state image pickup element 11 (see FIG. 3).
The signal processing unit 5 is configured as a signal reading circuit of a known solid-state image pickup device, reads a current signal according to the light intensity received by the one-dimensional solid-state image pickup device 11, and outputs this signal. The shape of the laser beam LB is measured by processing with a predetermined algorithm. Further, the signal processing section 5 outputs a timing signal corresponding to the reading of the signal to the driving section 4.

A procedure for measuring the laser beam shape using the measuring apparatus having this configuration will be described. First, the slider 14 is moved on the guide rail 13 to move the sensor unit 2 to the laser beam L.
After being set at a predetermined position on the axis of B, the sensor holder 16 is rotated with respect to the post 15 and the one-dimensional solid-state imaging device 11
As shown in FIG. 1, the shutter mechanism 12 is arranged such that the sensor unit 2 is directly opposed to the laser beam LB with the length direction thereof oriented in the vertical vertical direction, and the control unit 3 outputs the signal of the one-dimensional solid-state image pickup device 11. Start reading. Then, the signal processing unit 5 sends a timing signal to the driving unit 4, and the control circuit 33 of the driving unit 4 outputs the “H” signal to the output terminal.
As a result, the drive circuit 31 is driven and outputs a drive signal to the drive signal lines a and c, so that the liquid crystal portion facing the transparent electrode 22a is in a voltage applied state, and the light transmittance of this region is reduced. Therefore, the solid-state imaging device 11 receives light by every other device corresponding to the transparent electrode 22b, and its signal output is output by the signal processing unit 5 as shown in FIG.
Read out.

Then, the timing signal from the signal processing section 5 is sent to the drive section 4, and the control circuit 33 of the drive section 4 outputs the "L" signal to the output terminal. As a result, the drive circuit 3
2 is in a drive state and outputs a drive signal to the drive signal lines b and c, so that the light transmittance of the region corresponding to the transparent electrode 22b is reduced. Therefore, the solid-state imaging device 11 receives light at every other device corresponding to the transparent electrode 22a, that is, the device between the previously received devices, and its signal output is processed as shown in FIG. 4B. It is read by the unit 5.

Then, in the signal processing unit 5, the previous signal and the current signal are added on the coordinate axes to obtain individual solid-state image pickups arranged in the light beam diameter direction as shown in FIG. 4C. It is possible to obtain data on the light intensity in the device. Therefore, by calculating the light intensity distribution of the light beam in the beam radial direction based on this data by the Gaussian distribution approximation formula, as shown in FIG. The continuous light intensity distribution can be calculated, and the laser beam diameter can be measured by applying a predetermined threshold value TH to this light intensity distribution.

Therefore, while the slider 14 is moved on the guide rail 13 to move the sensor unit 2 along the optical axis of the laser beam LB, the above-described measurement is performed at a plurality of moving positions, so that each moving position is moved. Laser beam diameter can be measured. For example, as shown in FIG. 5, measurement results at a plurality of points P1 to P5 are (a) to (e), respectively.
Then, by obtaining these envelopes, the beam shape of the laser beam LB in the vertical sectional direction can be measured.
Further, the beam waist position of the laser beam can be measured from this measurement result. In this case, P3 is the beam waist position.

When the laser beam diameter is two-dimensionally measured, the sensor holder 16 as shown by the chain line in FIG.
Is rotated by 90 degrees with respect to the post 15 and the one-dimensional solid-state image pickup device 11 and the shutter mechanism 12 are oriented in the horizontal direction, and the polarization direction of the laser beam LB is set in the direction parallel to the Y axis. By performing the previous measurement and 90
The beam diameter in different directions can be measured. Further, based on the beam diameter measured in this way, FIG.
As described above, the beam shape can be measured three-dimensionally. That is, in this case, the beam shape measured at each point of P1 to P5 is measured as shown in (a) to (e) of the same figure, and the beam shape is measured three-dimensionally from this result. .

As described above, in the present embodiment, since light is received in a state where every other one-dimensional solid-state image pickup device is masked, the light received by one device causes the blooming phenomenon to the adjacent device. Even if an influence occurs, the adjacent elements do not receive light at that time, and therefore, there is no influence of the plume phenomenon. Therefore, it is possible to prevent the measurement accuracy from deteriorating due to the blooming phenomenon, and it is possible to perform highly accurate measurement.

Here, in the above-mentioned embodiment, a set of transparent electrodes is formed every other solid-state image pickup element and the light transmittance is changed by switching to two steps. However, as shown in FIG.
It is also possible to configure three sets of the transparent electrodes 22a, 22b, and 22c every other two, and selectively drive them sequentially to switch to three stages and perform the measurement while changing the light transmittance. By doing so, it is possible to more effectively prevent the influence of the blooming phenomenon due to the adjacent element.

Further, as shown in FIG. 8, a two-dimensional solid-state image pickup device (not shown) in which a light receiving element array is arranged in a matrix is used, and a shutter mechanism uses a liquid crystal 21A in which transparent electrodes 22 are arranged in a matrix. The light intensity of the laser beam is two-dimensionally detected by one measurement by forming a set of the electrodes 22 in the vertical and horizontal directions at intervals of 1 or more and selectively driving them to control the change of the light transmittance. Therefore, it is possible to obtain a large number of measurement signals with a small number of times and perform quick measurement.

FIG. 9 is a diagram showing a second embodiment of the present invention and is a perspective view showing the structure of the sensor section. Here, the light shielding plate 41 is used as the shutter mechanism 12 of the sensor unit 2. In the second embodiment as well, the sensor unit 2 is assumed to be mounted on the same sensor holder 16 as that shown in the first embodiment. As the shutter mechanism, 1
The front side of the one-dimensional solid-state image sensor 11 is a light-shielding plate 41 having a plurality of windows 42 arranged in series at a pitch dimension corresponding to every other element of the dimensionally fixed image sensor, that is, a pitch dimension twice the pitch dimension of the element. And is supported by a bracket (not shown) so as to be movable in the longitudinal direction thereof, that is, in the case of FIG. Further, in order to adjust the light shielding plate 41 to an intermediate position in the vertical direction, the spring 4 is provided between the light shielding plate 41 and the sensor holder 16.
Hang up 3. Then, magnetic bodies 44 are attached to both ends of the light shielding plate 41, respectively.

On the other hand, on both the upper and lower sides of the light shield plate 41, the electromagnets 45, which are separated from the magnetic body 44 by the pitch dimension of the light receiving element array of the one-dimensional solid-state image pickup device 11, respectively.
46 is arranged, and these electromagnets 45 and 46 are fixedly supported by the sensor holder 16. Also, these electromagnets 4
A drive unit 4 similar to that shown in FIG. 3 is connected to the motors 5 and 46 so that the electromagnets 45 and 46 are selectively energized.

Therefore, in the sensor unit having this structure, as shown in FIG. 10A, for example, the sensor unit 2 is set in the vertical vertical direction and then the driving unit 4 is used to set the electromagnet 45 on one side (upper side). When energized, an attractive force due to magnetic force acts between the electromagnet 45 and the magnetic body 44, and the light shielding plate 41 is moved upward. As a result, every other one-dimensional solid-state image pickup device is opened through the window 42 provided in the light shielding plate 41, and the laser beam is received to output a signal.
Next, as shown in FIG. 10B, if the other (lower) electromagnet 46 is energized, the electromagnet 46 and the magnetic body 4 are turned on.
4, the light blocking plate 41 is moved downward by one pitch of the light receiving element array, and one element different from the previous one is opened by the window 42 of the light blocking plate 41, and It receives a beam and outputs a signal.

As a result, the same signal as in the first embodiment can be obtained and the beam waist position of the laser beam can be measured. Therefore, also in the second embodiment, even if the light reception by one element affects the adjacent element by the blooming phenomenon, the light reception by the adjacent element is not performed at that time, and the plumming is performed. Without being affected by the phenomenon, it is possible to prevent the measurement accuracy from deteriorating due to the blooming phenomenon, and it is possible to perform highly accurate measurement.

When the laser beam diameter is two-dimensionally measured, the sensor holder is rotated 90 degrees with respect to the post as in the first embodiment, and the one-dimensional solid-state image pickup device and the shutter mechanism are horizontally moved. It goes without saying that the same measurement can be performed in the state toward. Further, the laser beam can be measured three-dimensionally by moving the sensor unit along the optical axis direction of the laser beam, as in the first embodiment.

Further, a two-dimensional solid-state image pickup device may be used, and windows may be opened in a matrix in the light shielding plate, and the light shielding plate may be moved in the horizontal and vertical directions by one pitch each. With this configuration, the light intensity of the laser beam can be two-dimensionally detected by one measurement, and a large number of measurement signals can be obtained with a small number of times to perform quick measurement.

Also in this case, the window pitch dimension is set to 2
If the pitch is set to be equal to or more than the pitch and the light shielding plate is intermittently moved from the first position to the third position, the influence of the blooming phenomenon due to the adjacent elements can be more effectively prevented.

[0028]

As described above, according to the present invention, the sensor section in which a plurality of light receiving elements are arranged is driven by the driving means to selectively and sequentially operate the plurality of light receiving elements to obtain a signal, Since the light beam shape is recognized in the signal processing means based on this signal, it becomes possible to obtain the signals from the adjacent light receiving elements while being temporally separated, and avoiding the blooming phenomenon between the adjacent light receiving elements. Highly accurate output can be obtained, and the light beam shape can be measured with high accuracy.

Further, the sensor section includes a one-dimensional solid-state image pickup device in which a plurality of light-receiving elements are arranged in a dimension longer than the light beam diameter, and the plurality of light-receiving elements arranged individually in front of the solid-state image pickup element. By configuring with a shutter mechanism capable of blocking light, it is possible to obtain a light intensity distribution in one direction for the light beam and measure the beam diameter in that direction. Therefore, if the measurement is performed at a position where the direction of the solid-state image sensor is changed, the light beam diameter can be measured two-dimensionally.

Alternatively, the sensor section includes a two-dimensional solid-state image pickup device in which a plurality of light-receiving elements are arranged in vertical and horizontal dimensions larger than a light beam diameter, and the plurality of light-receiving elements are arranged in front of the solid-state image pickup element. With the shutter mechanism capable of blocking light, the light intensity distribution of the light beam can be two-dimensionally measured by one measurement, and the measurement can be speeded up.

Further, the shutter mechanism is composed of a liquid crystal device, a plurality of transparent electrodes respectively corresponding to a plurality of light receiving elements are formed in an array, and the transparent electrodes are selectively and sequentially energized, Signals from adjacent light receiving elements can be selectively and sequentially obtained, and the blooming phenomenon can be avoided. Similarly, even if the shutter mechanism is composed of a light-shielding plate in which windows for transmitting light are arrayed, and this light-shielding plate can be moved in units of the arrangement pitch dimension of the light-receiving elements on a plane perpendicular to the axial direction of the light beam, Signals from adjacent light receiving elements can be selectively and sequentially obtained, and the blooming phenomenon can be avoided.

Further, the signal processing means uses the individual output signals of the plurality of light receiving elements as sampling data, calculates the light intensity distribution of the light beam in the beam diameter direction by a Gaussian distribution approximation formula, and obtains the obtained light intensity distribution characteristics. Thus, the beam diameter of the light beam can be measured, and the waist position of the light beam can be measured by performing measurement at different light beam positions.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a first embodiment of the present invention and an exploded configuration of a main part thereof.

FIG. 2 is a front view and a cross-sectional view of a sensor unit.

FIG. 3 is a circuit diagram showing an example of a control unit.

FIG. 4 is a diagram showing an output signal for explaining the operation of the signal processing unit.

FIG. 5 is a schematic diagram showing an example of a method for measuring a beam waist.

FIG. 6 is a schematic diagram showing an example of a method for measuring a beam shape.

FIG. 7 is a cross-sectional view showing the configuration of a modified example of the sensor unit of the first embodiment.

FIG. 8 is a perspective view showing the configuration of another modified example of the sensor unit of the first embodiment.

FIG. 9 is a perspective view of a sensor unit according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view for explaining the operation of the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light beam shape measuring device 2 Sensor part 3 Control part 4 Driving part 5 Signal processing part 11 One-dimensional solid-state image sensor 12 Shutter mechanism 21 Liquid crystal 22,23 Transparent electrode 24 Polarizing plate 31,32 Driving circuit 33 Control circuit 41 Light-shielding plate 42 Window 44 magnetic material 45,46 electromagnet

Claims (7)

[Claims] 1. A sensor unit comprising a plurality of light receiving elements for receiving a light beam to be measured and outputting a signal corresponding to the light intensity, and driving the sensor unit to selectively and sequentially operate the light receiving elements. And a signal processing means for recognizing a light beam shape by processing signals output from the respective light receiving elements. 2. The sensor unit includes a one-dimensional solid-state imaging device in which a plurality of light receiving elements are arranged in a dimension longer than a light beam diameter,
The light beam shape measuring apparatus according to claim 1, wherein the measuring device is a front side of the solid-state image pickup device and comprises a shutter mechanism capable of individually shielding the plurality of light receiving elements. 3. The sensor unit comprises a two-dimensional solid-state image sensor in which a plurality of light-receiving elements are arranged in a vertical and horizontal dimension larger than a light beam diameter, and the plurality of light-receiving elements located in front of the solid-state image sensor. The light beam shape measuring apparatus according to claim 1, wherein the shutter mechanism is capable of blocking light. 4. The shutter mechanism is a liquid crystal device, wherein a plurality of transparent electrodes respectively corresponding to a plurality of light receiving elements are formed in an array, and the transparent electrodes are selectively and sequentially energized. 3. Measuring device of light beam shape. 5. The shutter mechanism is a light-shielding plate in which light-transmitting windows are arranged in an array, and the light-shielding plate can be moved on a plane perpendicular to the axial direction of the light beam in units of the arrangement pitch dimension of the light-receiving elements. The light beam shape measuring device according to claim 2 or 3. 6. The light beam shape measuring device according to claim 5, wherein an electromagnet is arranged on at least one side of the light shielding plate, and the light shielding plate is moved by a magnetic force when the electromagnet is energized. 7. The signal processing means uses the individual output signals of the plurality of light receiving elements as sampling data, calculates the light intensity distribution of the light beam in the beam radial direction by a Gaussian distribution approximation formula, and obtains the obtained light intensity distribution characteristics. 7. The light beam shape measuring device according to claim 1, wherein the waist position of the light beam diameter is measured by measuring the beam diameter of the light beam from the laser beam and performing the light beam diameter at different axial positions of the light beam. .