CN102628811B - Verifying device of grating groove defect - Google Patents

Abstract

A verifying device of a grating groove defect aims at resolving the problem that a main ruler has the conditions of stain and inconsistency of front and back phases in the manufacture process of a grating ruler, and a manual method cannot finish verifying of the grating ruler. A first shifting driving device of the verifying device drives a signal detection head to move along the detection direction, the signal detection head detects light transmitted by a light source and modulated by a grating to be measured and a standard grating, the light is converted into electric signals through a photoelectric detector, amplification processing and analog-digital conversion are conducted through a signal processing module on the electric signals, finally a pulse detection module is used for detecting and scoring the defect and copying existence and position of the defect through pulse signals, a second shifting driving device moves the position of the standard grating, and the processing is repeated till the detection finished. The verifying device is used for measuring the defect of long grating, groove evenness detection and phase consistency detection of a length grating ruler.

Description

Grating line fault detection device

Technical field

The present invention relates to a kind of grating scale groove fault detection device.

Background technology

The top priority realizing grating displacement sensor high-acruracy survey is the delineation and the accuracy of repetition that ensure master grating, and dividing precision is usually higher, but also there is black and white than the situation such as undesirable; There is the stain caused because environment clean level is not high in reproduction process, or light exists the situations such as certain distortion and can have influence on phase equalization etc., these all can have a strong impact on the precision of last grating scale.Moreover, the spreading error existed in grating spreading process, also can reduce precision and the performance of whole grating scale greatly.

General grating scale delineation or after copying, because data volume is comparatively large, utilizes general microscope, cannot with the naked eye complete detection dividing precision.Simultaneously, phase place inconsistent with the naked eye observation in front and back cannot be accomplished, if can specific checkout equipment be made, utilize effective detection means, focus stain that grid chi main scale exists automatically and front and back phase place is inconsistent carries out record, so effectively can improve the precision of finished product grating scale, enhance productivity and the quality of production.

Summary of the invention

The present invention, for solving the situations such as main scale in existing grating scale manufacture process exists stain and front and back phase place is inconsistent, by manually completing the problem of grating scale inspection, provides a kind of grating line fault detection device.

Grating line fault detection device, this device comprises master grating, acquisition of signal head, the first shift drive, the second shift drive, signal processing module and pulse detection module; Described first shift drive along the length direction of scanning movable signal detecting head of master grating, the intensity signal after the modulation of described acquisition of signal head record,

Second shift drive is for driving the shift position of master grating, and described signal processing module receives the positional information of the master grating that the displacement information of the first shift drive, the intensity signal of acquisition of signal head output and the second shift drive export; And described positional information is carried out signal amplification and digital-to-analog conversion process, export pulse detection module to; Described pulse detection module detects the signal received, and analyzes the positional information of grating line defect to be measured;

Detailed process is: described pulse detection module, records all scan-datas, treats this segment standard raster scanning complete, then analyzes the position at grating ruling defect to be measured and replication defective place;

First the amplitude by demarcating in advance changes with phase differential, is expressed as with formula one:

Formula one, $A=A_0\×\cos (2\×\mathrm{\π}\×\frac{x}{T})+B_0;$

In formula, A is the output valve of signal processing module, A ₀, B ₀be constant, π represents circular constant, and T is the groove cycle of master grating, and x is the offset deviation with phase differential equivalence;

Then the output valve A of all points read is averaged, obtains mean value M, show that phase differential mean difference formula two is expressed as:

Formula two, $\mathrm{\θ}={\cos }^{-1}\left(\frac{M-B_0}{A_0}\right);$

Finally, then the phase place corresponding to amplitude of each point of point-to-point analysis, calculate the phase differential corresponding to amplitude change, judge that whether grating to be measured is qualified according to the requirement of phase differential.

Beneficial effect of the present invention: the invention provides a kind of principle simple, effectively can detect stain and the inconsistent device of phase place.Device of the present invention records the performance of grating scale to be measured automatically, thus judges whether grating scale to be measured meets the requirement of producing fast and accurately.

Accompanying drawing explanation

Fig. 1 is the schematic diagram of grating line fault detection device of the present invention;

Fig. 2 is the schematic diagram that in grating line fault detection device of the present invention, pulse detection module detection signal output amplitude changes with distance;

Fig. 3 is that in grating line fault detection device of the present invention, pulse detection module detected phase deviation changes schematic diagram with distance;

Fig. 4 is the schematic diagram of acquisition of signal head in grating line fault detection device of the present invention.

Embodiment

Composition graphs 1 illustrates present embodiment, grating line fault detection device, this pick-up unit comprises master grating 3, acquisition of signal head 1, first shift drive 7, second shift drive 9, signal processing module 8, pulse detection module 10, and acquisition of signal head 1 comprises light source 5, optical system 6, input chip 2 further.First shift drive 7, drive singal detecting head 1 shift position; Second shift drive 9 drives master grating 3 shift position; Signal processing module 8 carries out conversion process to the information obtained from acquisition of signal head 1, first shift drive 7, second shift drive 9; Pulse detection module 10 is for the PHASE DISTRIBUTION of analytical calculation grating 4 to be measured; Master grating 3 is the standardized components for detecting grating to be measured, it has higher graduating accuracy, normally pass through the qualified master grating of standard test, its pitch is equal with the target pitch of grating to be measured, its black and white is also up to the standards than deviation, and the quality of master grating 3 determines the precision of detection.This light source 5 can be laser diode, sends coherent light.The light that light source sends by optical system 6 changes into collimated ray, is irradiated on grating 4 to be measured.The position of acquisition of signal head 1 is controlled by the first shift drive 7, and the first shift drive 7 makes acquisition of signal head 1 move in a scanning direction.Acquisition of signal head 1 detects what light source 5 sent, and by light signal that grating 4 to be measured, master grating 3 are modulated, and be converted into electric signal, carry out amplification by signal processing module 8 to process and analog to digital conversion, finally delineated existence and the position thereof of defect and replication defective by pulse signal detection by pulse detection module 10, then changed the position of master grating 3 by the second shift drive 9, repeat above process, until detect complete.

When acquisition of signal head 1 is scanned, the first shift drive 7 and the second shift drive 9 will adjust the position of acquisition of signal head 1 and master grating 3 respectively, and acquisition of signal head 1 is rescaned on the position that grating 4 to be measured is new.Input chip 2, as optical detection device, can select silicon photocell.

Pulse detection module 10 described in present embodiment, records all scan-datas, treats this of this segment standard grating 3 scanned, then analyzes existence and the position thereof that grating 4 to be measured delineates defect and replication defective.

Pulse detection module 10 described in present embodiment, records all scan-datas, to be scanned all complete, then analyzes existence and position thereof that grating 4 to be measured delineates defect and replication defective.

The workflow of apparatus of the present invention is: on device, first place grating 4 to be measured, acquisition of signal head 1, master grating 3 is placed in initial position, first shift drive 7 is along the position of direction of scanning movable signal detecting head 1, speed can set, acquisition of signal head 1 records the intensity signal in moving process, signal processing module 8 is according to the shift information of the first shift drive 7, the positional information of master grating 3 obtained from the second shift drive 9 and the output information of acquisition of signal head 1, and by base conditioning such as signal amplification and digital-to-analog conversions, obtaining is the relation of position and amplitude within the scope of L in master grating 3 length, and export to pulse detection module 10, pulse detection module 10 pairs of signal detection information are analyzed, then the second shift drive 9 moves master grating 3 to new assigned address, first shift drive 7 adjusts acquisition of signal head 1 to new initial position, repeat above-mentioned scan operation, until complete the scanning work treating light-metering grid 4, what be worth proposition is, pulse detection module 10 pairs of signal detection information are carried out analysis and can be carried out piecemeal above, also can until scanning work be complete analyzes again, as for analyzing piecemeal, so need one section of overlapping part between adjacent segment, so that the phase equalization information between the section of obtaining and section.

Below the analytic process of input data is illustrated.

Composition graphs 2 is scan the relation curve between one section of detecting distance and signal output amplitude obtained, and the amplitude first by demarcating in advance is expressed as with phase differential change formula one:

$A=A_0\×\cos (2\×\mathrm{\π}\×\frac{x}{T})+B_0$ Formula one

Here A represents the output valve of signal processing module 8, A ₀, B ₀be constant, π represents circular constant, and T represents the groove cycle of master grating 3, and as 20 microns, x is the offset deviation with phase differential equivalence.

First all points read are averaged, obtain mean value M, know that phase differential mean difference formula two is expressed as:

$\mathrm{\θ}={\cos }^{-1}\left(\frac{M-B_0}{A_0}\right);$ Formula two

Here phase differential: $\mathrm{\θ}=2\×\mathrm{\π}\×\frac{x}{T}.$

And then the phase place corresponding to amplitude of each point of point-to-point analysis, because inverse cosine function may have two results, but due to the continuity between consecutive point, only need to get arbitrarily a wherein value, we still can calculate the phase differential corresponding to amplitude change.By calculating, we just know that phase differential is along with the change of distance on any one section, composition graphs 3, only need to require just to judge that whether grating to be measured is qualified according to given reference phase difference, such as, when setting phase differential requires to be 5 °, so Fig. 3 mid point A place is just defective place, so can judge, owing to treating dipping in the existence pollution of A point place or spot not by detecting.

Below the method detecting phase equalization before and after whole chi is introduced.

Composition graphs 1, scans the first time of master grating 3 when the first shift drive 7 completes, and pulse detection module 10 being divided into two sections, front and back at sweep length L, and can be averaging two sections, front and back simultaneously to phase place, obtain θ respectively ₂and θ ₁, thus obtain first half section and the phase difference between the second half section ₁,

Wherein: Δ ₁=θ ₂-θ ₁.

Move master grating 3 by the second shift drive 9, displacement is first shift drive 7 drive singal detecting head 1 completes and scans the second time of master grating 3, by asking the mode of first half section and second half section phase differential to obtain in second time scanning above, and the phase difference of first half section and second half section ₂, so until to treat light-metering grid 4 scanned, obtain every the phase differential of distance, Δ ₁, Δ ₂, Δ ₃, Δ ₄, Δ ₅...

If phase differential curve before and after requiring, only need to add up piecemeal to above phase place, such as require the phase difference between the 1st section to the 5th section, often here distance is one section, obtains formula:

Claims (3)

1. grating line fault detection device, this device comprises master grating (3), acquisition of signal head (1), the first shift drive (7), the second shift drive (9), signal processing module (8) and pulse detection module (10); It is characterized in that,

Described first shift drive (7) is along length direction of scanning movable signal detecting head (1) of master grating (3), intensity signal after the modulation of described acquisition of signal head (1) record, second shift drive (9) for driving the shift position of master grating (3), the positional information of the intensity signal that described signal processing module (8) receives the displacement information of the first shift drive (7), acquisition of signal head (1) exports and the master grating (3) that the second shift drive (9) exports; And described positional information is carried out signal amplification and digital-to-analog conversion process, export pulse detection module (10) to;

Described pulse detection module (10) is detected the signal received, and analyzes the positional information of grating to be measured (4) groove defect;

Detailed process is: described pulse detection module (10), records all scan-datas, treats master grating (3) scanned, then analyzes the position at grating to be measured (4) delineation defect and replication defective place;

Scan piecemeal master grating (3), detailed process is as follows:

First the amplitude by demarcating in advance changes with phase differential, is expressed as with formula one:

Formula one, $A=A_0\×\cos (2\×\mathrm{\π}\×\frac{x}{T})+B_0;$

In formula, A is the output valve of signal processing module (8), A ₀, B ₀be constant, π represents circular constant, and T is the groove cycle of master grating (3), and x is the offset deviation with phase differential equivalence;

Then the output valve A of all points read is averaged, obtains mean value M, show that phase differential mean difference formula two is expressed as:

Formula two, $\mathrm{\θ}={\cos }^{-1}\frac{(M-B_0)}{A_0};$

Finally, then the phase place corresponding to amplitude of each point of point-to-point analysis, calculate the phase differential corresponding to amplitude change, judge that whether grating to be measured (4) is qualified according to the requirement of phase differential.

2. grating line fault detection device according to claim 1, it is characterized in that, described acquisition of signal head (1) comprises light source (5), optical system (6) and input chip (2), the light signal that light source (5) sends is converted into collimated light through optical system (6), and input chip (2) is for detecting the intensity signal after grating to be measured (4) and master grating (3) modulation.

3. grating line fault detection device according to claim 1, is characterized in that, described pulse detection module (10) calculates the phase differential between each location point by signal amplitude.