JP2002062260A - Diffraction element reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive diffraction element reader. SOLUTION: In this diffraction element reader wherein outgoing light emitted from an LD (light source) 17 is emitted to a diffraction element 13 on a specimen 11, wherein the diffracted light diffracted by the element 13 is guided to a PD(photodiode) 19, and wherein the element 13 is read based on an output from the PD 19, the LD 17 is moved relatively with respect to the diffraction element 13 at a prescribed speed to read the element 13 based on a time-serial change of the output from the PD 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for irradiating a diffraction element on a test object with light emitted from a light source, guiding the diffraction light diffracted by the diffraction element to a light receiving element, and outputting the light from the light receiving element. The present invention relates to a diffraction element reading device that reads the diffraction element based on the above.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of a conventional diffraction element reader. In the figure, a hologram diffraction element 3 is provided on a test object 1.

A light source 7 for emitting light in the direction of the test object 1 and a CCD 9 for detecting the diffracted light of the diffraction element 3 are provided in the diffraction element reader 5. At this time, light having a light amount distribution as shown in FIG.

A diffraction element is read from the pattern of the light quantity distribution.

[0005]

However, in the diffractive element reader having the above structure, it is necessary to accurately read the light amount distribution of the diffracted light from the diffractive element 3 which spreads over a wide range. Has to be used, and there is a problem that it is expensive.

[0006] The present invention has been made in view of the above problems, and a first object of the present invention is to provide an inexpensive diffraction element reader. A second object is to provide a diffraction element reader that can read a plurality of diffraction elements.

[0007] A third object is to provide a diffraction element reader capable of performing accurate reading.

[0008]

According to a first aspect of the present invention, a light emitted from a light source is irradiated on a diffraction element on a test object, and the diffracted light diffracted by the diffraction element is emitted. A diffraction element reader that guides the light receiving element and reads the diffraction element based on an output from the light receiving element,
A diffractive element reader, wherein the light source and the diffractive element are relatively moved at a predetermined speed, and the diffractive element is read based on a time change of an output from the light receiving element.

In the case where the grating constant and the grating vector of the diffraction element have a certain distribution, the intensity of the diffracted light incident on the light receiving element changes by relatively moving the light source and the diffraction element at a predetermined speed.

The diffraction element can be read based on the temporal change of the intensity of the diffracted light, that is, the temporal change of the output from the light receiving element. Since only a temporal change in the intensity of the diffracted light is observed, the detection can be performed without using a light receiving element having a large number of pixels with multiple divisions.

Here, from the viewpoint of improving the reading accuracy and the reading speed when reading the diffraction element, a second aspect is provided.
As in the invention described above, it is preferable that a table in which a pattern of the time change of the output from the light receiving element is recorded is provided in a memory inside or outside the apparatus, and the diffraction element is read by referring to the table.

The invention described in claim 3 is the first or second invention.
The light receiving element according to the invention described in any one of the claims is a multi-segment PD, a PSD, or a plurality of PDs.

Since the light receiving element is one of a multi-divided PD, a PSD, and a plurality of PDs, it can detect not only the temporal change of the intensity of the diffracted light but also the intensity distribution of the diffracted light. Accuracy and speed are improved.

According to a fourth aspect of the present invention, there is provided an optical device according to any one of the first to third aspects, wherein the light emitted from the light source is split into a plurality of light beams between the light source and the diffraction element. The diffraction element reader according to the above, further comprising means.

[0015] By providing an optical means for splitting outgoing light emitted from the light source into a plurality of light beams and applying the split light beam to a plurality of different diffraction elements, a single light source can read a plurality of diffraction elements. Down can be planned.

According to a fifth aspect of the present invention, there is provided a diffractive element reader according to any one of the first to fourth aspects, wherein the light source comprises a plurality of light sources emitting light of different wavelengths.

The diffraction efficiency and the diffraction direction of the diffraction element depend on the wavelength of light to be irradiated. Since the light source includes a plurality of light sources that emit light of different wavelengths, light of different wavelengths can be applied to the diffraction element. For this reason, the diffraction information of the diffraction element is obtained at a plurality of irradiation wavelengths, and the reading accuracy is improved.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described with reference to the drawings. (1) First Embodiment A description will be given with reference to FIG. 1 which is a configuration diagram showing a first embodiment.

In FIG. 1, a diffraction element 13 such as a hologram is provided on a test object 11. Note that the diffraction element 13 of the present embodiment has a distribution with a lattice constant and a lattice vector.

In the diffraction element reading device 15, the test object 11
LD17 as a light source for emitting light in the direction, and LD17
A collimator lens 14 for converting light from the light into a parallel light beam, and an undivided PD as a light receiving element for detecting the diffracted light of the diffractive element 13 are provided.

In order to relatively move the LD 17 and the diffraction element 13 at a predetermined speed, a transport mechanism 21 for transporting the test object 11 in the direction of arrow I is provided. As the test object 11 moves in the direction of the arrow I by the transport mechanism 21, the intensity of the diffracted light of the diffraction element 13 changes with time,
The output of the PD 19 also changes with time.

The output of the PD 19 is amplified by an amplifier 23 and converted into a digital signal by an AD converter 24.
It is input to the reading unit 25. Reference numeral 33 denotes a table in which a pattern of intensity change of the diffracted light from the diffraction element 13 to be read over time, that is, a change of the output of the PD 19 over time is recorded in an internal memory, and 35 is a display unit for displaying a read result. It is.

Next, the operation of the diffraction element reader having the above configuration will be described. The control unit 31 controls the LD 1 via the driver 29.
7 is driven, and light is emitted from the LD 17 toward the test object 11.

The light emitted from the LD 17 is converted into a parallel light beam by the collimator lens 14 and enters the diffraction element 13 on the test object 11. The control unit 31 drives the transport mechanism 21 via the driver 27 to transport the test object 11 in the direction of the arrow I.

The diffracted light from the diffraction element surface 13a of the diffraction element 13 is incident on the light receiving surface 19a of the PD 19. PD19
Is amplified by an amplifier 23, and an analog signal is converted into a digital signal by an AD converter 24.
5 is input.

The reading unit 25 refers to the table 33 recorded in the internal memory, and the PD 19 that changes with time.
The diffraction element 13 is read from the output of. The read result is sent to the control unit 31, and the control unit 31 displays the read result on the display unit 35.

According to the above configuration, when the diffraction element 13 has a certain distribution of lattice constants and lattice vectors, the transport mechanism 21 is used to relatively move the LD 17 and the diffraction element 13 at a predetermined speed, whereby the PD 19 Changes the intensity of the diffracted light incident on.

The reading of the diffraction element 13 can be performed based on the temporal change of the intensity of the diffracted light, that is, the temporal change of the output from the PD 19. Since we only look at the temporal change in the intensity of the diffracted light, C
Without using a light-receiving element such as a CD, an inexpensive undivided PD 19 can also be detected, resulting in an inexpensive diffraction element reader.

Further, a table 33 in which the pattern of the time change of the output of the PD 19 is recorded in the internal memory is provided, and the reading unit 25 reads the diffraction element 13 with reference to the table 33, so that the reading accuracy and the reading speed are improved. improves.

The present invention is not limited to the above embodiment. In the above embodiment, in order to relatively move the LD 17 and the diffraction element 13 at a predetermined speed,
Although the transport mechanism 21 that transports the test object 11 in the direction of the arrow I is provided, the diffraction element reading device 15 may be moved in reverse.

In the above-described embodiment, the non-divided PD 19 is used as the light receiving element.
D or any of a plurality of PDs. In this case, for example, as shown in FIG. 2, when a two-divided PD 39 is used as the multi-divided PD, the output of each element is A, B
Then, by observing the value of AB, it can be understood how strongly the diffracted light hits the PD 39 divided into two parts,
Then the diffraction angle is also known. That is, in addition to the temporal change in the intensity of the diffracted light, the intensity distribution and the diffraction angle of the diffracted light can also be detected. By recording the data of the intensity distribution and the diffraction angle of the diffracted light in the table 33, the detection accuracy and Speed is improved.

Also, in FIG.
When 9 'is used, if each output is A and B, (A-
By looking at the value of (B) / (A + B), it is possible to know where the centroid of the diffracted light is located in the two-divided PSD. That is, in addition to the temporal change in the intensity of the diffracted light, the intensity distribution of the diffracted light can also be detected. By recording the data of the intensity distribution and the diffraction angle of the diffracted light in the table 33, the detection accuracy and speed are improved. I do.

Further, even if LED light is irradiated on the diffraction element instead of LD light, a certain degree of diffraction occurs, so that an LED may be used instead of the LD 17 as a light source. That is, the light source is not particularly limited as long as diffraction occurs when reflected by the diffraction element.

(2) Second Embodiment A second embodiment will be described with reference to FIG. In the figure, a plurality of diffraction elements, in this embodiment, three diffraction elements 53, 55, and 57 are provided on a test object 51.

Then, the test object 51 is transported in a direction perpendicular to the paper surface. The light emitted from the light source 59 is converged by an aperture 61, branched into three light beams by a beam splitter 62, and irradiated onto the diffraction elements 53, 55, and 57 on the test object 51 via an irradiation condenser lens 64. You.

The diffracted light from each of the diffraction elements 53, 55 and 57 reaches the light receiving elements 63, 65 and 67. According to such a configuration, the beam splitter 62 is provided as an optical unit that splits outgoing light emitted from the light source 59 into a plurality of light beams,
A plurality of diffractive elements 53, 55, and 57 that separate the split light flux are used.
, A plurality of diffraction elements 53, 55, and 57 can be read by one light source 59, and the cost can be reduced.

Although a beam splitter is used as an optical means for splitting a light beam, a half mirror or a Wollaston prism may be used. Alternatively, light emitted from the light source 59 may be guided to an optical fiber, and the optical fiber may be split into three. Then, the output end face of the separated optical fiber is connected to the diffraction elements 53, 55,
57.

(3) Third Embodiment A third embodiment will be described with reference to FIG. In FIG. 4, the same parts as those in FIG. 1 for describing the first embodiment are denoted by the same reference numerals, and overlapping description will be omitted.

In this embodiment, two light sources, that is, a first LD (blue LD) 17 and a second LD (red LD) 17 'having different wavelengths of emitted light are used as light sources.

These LDs 17 and 17 'are controlled by a control unit 31 via drivers 29 and 29', respectively. According to such a configuration, the first L having different wavelengths is used.
The diffracted lights of D17 and the second LD 17 'have different diffraction efficiencies and directions of the diffracted lights, respectively, that is, the first LD1
7 and the diffracted light by the second LD 17 ′ have different amounts of light received by the PD 19. Due to this difference in the amount of received light, the diffraction element can be read with high accuracy.

In the above embodiment, the first LD
Although the description has been made with reference to the example in which an LD is used as the second LD 17 'and the second LD 17', LEDs having different wavelengths, for example, blue LEDs and red LEDs may be used.

[0042]

As described above, according to the first aspect of the present invention, when the grating constant and the grating vector of the diffraction element have a certain distribution, the light source and the diffraction element are relatively moved at a predetermined speed. This changes the intensity of the diffracted light incident on the light receiving element.

The diffraction element can be read based on the temporal change of the intensity of the diffracted light, that is, the temporal change of the output from the light receiving element. Since only a temporal change in the intensity of the diffracted light is observed, the detection can be performed without using a light receiving element having a large number of pixels with multiple divisions, and an inexpensive diffraction element reader can be obtained.

According to the second aspect of the present invention, there is provided a table in which a pattern of a time change of the output from the light receiving element is provided, and the diffraction element is read by referring to the table. At the time of reading accuracy,
And the reading speed is improved.

According to the third aspect of the present invention, the light receiving element is one of a multi-divided PD, a PSD, and a plurality of PDs. The intensity distribution of the diffracted light can also be detected, and the detection accuracy and speed are improved.

According to the fourth aspect of the present invention, there is provided an optical unit for branching outgoing light emitted from the light source into a plurality of light beams,
By applying the split light beam to a plurality of different diffraction elements, a plurality of diffraction elements can be read by one light source, and cost can be reduced.

According to the fifth aspect of the invention, the diffraction efficiency and the diffraction direction of the diffraction element depend on the wavelength of the irradiated light. Since the light source includes a plurality of light sources that emit light of different wavelengths, light of different wavelengths can be applied to the diffraction element. For this reason, the diffraction information of the diffraction element is obtained at a plurality of irradiation wavelengths, and the reading accuracy is improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment.

FIG. 2 is a configuration diagram illustrating a modification of the first embodiment.

FIG. 3 is a configuration diagram illustrating a second embodiment.

FIG. 4 is a configuration diagram showing a third embodiment.

FIG. 5 is a configuration diagram of a conventional diffraction element reader.

6 is a diagram illustrating an example of a light receiving surface of the CCD in FIG.

[Explanation of symbols]

 Reference Signs List 11 test object 13 diffraction element 17 LD (light source) 19 PD (light receiving element)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G059 AA10 BB08 EE02 EE11 FF01 FF04 GG02 GG03 HH02 JJ12 JJ17 JJ22 JJ30 KK03 2H049 AA50 AA55 AA68

Claims (5)

[Claims] 1. A light beam emitted from a light source is applied to a diffraction element on a test object, a diffracted light beam diffracted by the diffraction element is guided to a light receiving element, and the diffraction element is operated based on an output from the light receiving element. A diffractive element reader for reading, wherein the light source and the diffractive element are relatively moved at a predetermined speed, and the diffractive element is read based on a time change of an output from the light receiving element. apparatus 2. The diffraction element reader according to claim 1, further comprising: a table on which a pattern of a time change of an output from the light receiving element is recorded, and wherein the diffraction element is read with reference to the table. 3. The light receiving element according to claim 1, wherein the light receiving element is a multi-division PD, a PSD,
3. The diffraction element reader according to claim 1, wherein the diffraction element reader is any one of a plurality of PDs. 4. The device according to claim 1, further comprising means for splitting outgoing light emitted from the light source into a plurality of light beams between the light source and the diffraction element. Diffraction element reader. 5. The diffraction element reader according to claim 1, wherein the light source comprises a plurality of light sources emitting light of different wavelengths.