CN102007389A - Photometer - Google Patents

Abstract

An optical receiver section (4) of a photometer (2) includes optical receiver elements (4a) disposed at a position corresponding to short wavelength-side light that is cut by a cut filter (26), wherein outputs from the optical receiver elements (4a) disposed at the position corresponding to the short wavelength-side light that is cut by the cut filter (26) are used as dark current outputs. An operational circuit (6) is provided with a correction circuit (30) that uses the dark current outputs to correct a photometer output from each of the optical receiver elements (4a) disposed at a position corresponding to long wavelength-side light rather than the short wavelength-side light to be cut.

Description

Metering device

technical field

The present invention relates to an improvement of a measuring device which separates light from an object to be measured to measure the luminance and the like of light of each wavelength.

Background technique

Conventionally, there is known a photometric device that splits wavelengths of light from an object to be measured to measure luminance and the like at each wavelength thereof.

As a photometric device in the prior art, light rays from an object to be measured are separated into wavelengths by a diffraction grating, and the light rays separated into wavelengths are received by a solid-state imaging device as a light-receiving part, and measured based on the output from the solid-state imaging device. Brightness, chromaticity, etc. of light of each wavelength.

In conventional photometry devices, dark current is output from the solid-state imaging device (dark current output) due to thermal noise even when light is not incident on the light receiving elements of the light receiving unit.

Therefore, a photometric device configured to perform multiple measurements is proposed, in which the dark current output from the solid-state imaging device is detected in a state where the light from the object to be measured does not enter the light receiving part, and then the output from the object to be measured is detected. The photometric output from the solid-state imaging device is detected by the light incident on the light receiving part, and the difference between the photometric output and the dark current output is obtained by calculation, so that the photometric output from each light receiving element is corrected by removing the dark current output.

In addition, a photometric device with a simultaneous measurement structure is also proposed. A cover is provided at the end of the light-receiving part, and the light from the object to be measured is not incident on the light-receiving element covered by the cover, and simultaneously detected. The dark current output of the light receiving element covered by the cover is compared with the photometric output from each light receiving element not covered by the cover, and the photometric output from each light receiving element is corrected (for example, refer to Patent Document 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 58-158528

Contents of the invention

However, although precise measurement is possible as a photometric device configured to perform multiple measurements, the disadvantage is that the measurement takes time.

In the photometric device configured for simultaneous measurement, although the measurement speed can be improved, it is disadvantageous in that a cover must be provided for the light-receiving part and the structure of the light-receiving part must be changed. In addition, the dark current output from each light-receiving element is not necessarily the same. Even if the dark current output from the light-receiving element covered by the cover is subtracted uniformly and the photometric output is obtained through correction, the dark current output may not be accurately eliminated. Therefore, from precision It is one of the existing deficiencies from the point of view of measurement.

An object of the present invention is to provide a photometric device capable of suppressing reduction in measurement accuracy and improving measurement speed without changing the structure of an existing light receiving unit.

The photometry device of the present invention is characterized in that it includes: a spectrophotometry optical system for splitting and measuring light from an object to be measured; a light receiving unit for receiving light separated by wavelength by the spectrophotometry optical system; An arithmetic circuit for calculating photometric characteristics based on the photometric output of the light receiving unit. The spectrophotometric optical system includes: a collimator lens that converts light from the object to be measured into parallel beams; A wavelength splitting element for splitting the light beam of the lens; a light collecting lens for collecting the light beams separated by wavelength on the light receiving part; a cut filter for blocking light rays on the shorter wavelength side than visible light, the The light-receiving unit has a plurality of light-receiving elements for respectively receiving light beams separated by wavelengths, the plurality of light-receiving elements are arranged in a constant direction corresponding to positions of specified wavelengths of the separated light rays, and the plurality of light-receiving elements are arranged In the position corresponding to the light on the short-wavelength side cut off by the cut filter, the output of the light-receiving element arranged at the position corresponding to the light on the short-wavelength side cut off by the cut filter is obtained as The dark current output is used, and a correction circuit is provided in the arithmetic circuit, and the correction circuit uses the dark current output to correct the long-wavelength side of light compared to the blocked short-wavelength side. The photometric output produced by each light receiving element at the position corresponding to the wavelength of light.

In the photometry device of the present invention, preferably, the cut filter is arranged before the collimator lens, and the cut filter is a colored glass filter for correcting the sensitivity of each wavelength.

In the photometry device of the present invention, preferably, the cutoff filter is arranged after the collimator lens, and the cutoff filter is a colored glass filter for correcting the sensitivity of each wavelength.

Furthermore, in the photometry device of the present invention, preferably, the cut filter cuts off light with a wavelength of 380 nm or less.

Furthermore, in the photometry device of the present invention, it is preferable that the correction circuit is connected to a storage unit that stores the output ratio of each light receiving element that is placed at the short wavelength that is cut off by the cut filter. The dark current output of the light receiving element at the position corresponding to the light on one side corresponds to the position corresponding to the light of each wavelength on the long wavelength side compared to the light on the short wavelength side that is blocked. The output of each light-receiving element on the above-mentioned light-receiving element, and it is the ratio of the output obtained by measurement under the condition that each light-receiving element is not illuminated; For the light on the wavelength side, the dark current output of each light receiving element at the position corresponding to the light of each wavelength on the long wavelength side.

According to the present invention, not only does not need to change the structure of the existing light receiving part, but also can suppress the reduction of the measurement accuracy, and can also obtain the effect of realizing the improvement of the measurement speed.

Description of drawings

FIG. 1 is an explanatory diagram showing the outline of the structure of the photometry device according to the present invention;

Fig. 2 is an optical characteristic diagram representing the transmittance of the cut-off filter of the present invention;

Fig. 3 is a top view of the light receiving part of the present invention;

4 is an explanatory diagram showing an example of a dark current output output from a line of each light receiving element according to the present invention.

Explanation of reference signs:

1Measurement object

2 light metering device

4 light receiving part

6 operation circuit

4a light receiving element

15 spectrophotometric optical system

26 colored glass filter (cut filter)

27 collimating lens

28 Diffraction gratings (wavelength resolution elements)

30 Correction circuit

Detailed ways

Hereinafter, embodiments of the photometry device according to the present invention will be described with reference to the drawings.

Example

FIG. 1 is an explanatory diagram showing an outline of the configuration of a photometric device such as a spectroradiometer according to the present invention. In FIG. 1 , 1 is a measurement object such as a liquid crystal panel, a signal lamp, a cold cathode tube, a guide lamp, and an LED, and 2 is a photometric device.

The photometry device 2 has an optical system 3 for receiving light from an object 1 to be measured, a light receiving unit 4 , and a circuit unit 5 . The circuit unit 5 has an arithmetic circuit 6 for calculating photometric characteristics (colorimetric data (brightness, chromaticity, color temperature)) based on the photometric output of the light receiving unit 4, an AC power supply 7, a DC-DC power supply 8, and an LCD display 9 , operation keys 10 , external synchronization input connector 11 , A/D converter 12 , CCD analog PCB (CCD analog printed circuit board) 13 .

The arithmetic circuit 6 is constituted by, for example, a CPU. The AC power supply 7 and the DC-DC power supply 8 are used to supply power to the arithmetic circuit 6 , and the operation keys 10 are used to input various instructions required for photometry to the arithmetic circuit 6 . The LCD display 9 is used to display photometric characteristics and other instructions. The external synchronization input connector 11 is used to instruct the timing of measurement in synchronization with the light emission of the measurement object 1 . The CCD analog PCB 13 is used for analog output of the photometry output of the light receiving unit 4 . The A/D converter 12 is used to convert the analog output into a digital output and input it to the arithmetic circuit 6 .

The optical system 3 is generally composed of an alignment optical system 14 and a spectrophotometry optical system 15 . The alignment optical system 14 is roughly composed of an objective lens 16 , a perforated mirror 17 , a total reflection mirror 18 , relay lenses 19 and 20 , a viewfinder shutter 21 , and an eyepiece 22 . Light from the object to be measured 1 passes through the objective lens 16 , is guided to the apertured mirror 17 , is reflected by the apertured mirror 17 , and is guided to the total reflection mirror 18 . The light guided to the total reflection mirror 18 is relayed to the position 1 conjugated to the measurement object 1 through the relay lenses 19 and 20, and the image of the measurement object 1 relayed to the conjugate position 1 passes through The eyepiece 22 is aimed at by the person to be measured. The viewfinder shutter 21 has the following effects, that is, it can prevent external light from passing through the relay lenses 20, 19, the total reflection mirror 18, and the perforated mirror 17 from one side of the eyepiece 22 when measuring the measurement object 1 with ultra-low brightness. into the spectrophotometric optical system 15.

The spectrophotometric optical system 15 not only has the objective lens 16 shared with the alignment optical system 14, the mirror with a hole 17, but also has a relay lens 23, an optical fiber bundle 24, a tower plate 25, a colored glass filter 26, a collimator Lens 27, diffraction grating 28, light collecting lens 29.

The apertured mirror 17 has an opening 17a. The perforated mirror 17 is used to adjust brightness. Here, four kinds of apertured mirrors are prepared, and FIG. 1 shows a state in which one of the apertured mirrors 17 is inserted into the optical path of the spectrophotometric optical system 15 .

The relay lens 23 forms an image of the measurement object 1 on the incident end surface 24 a of the optical fiber bundle 24 . The optical fiber bundle 24 functions to mix the light from the measurement object 1 and eliminate its polarization. The tower plate 25 has a transparent opening 25a, an ND filter 25b of 10 times light reduction, an ND filter 25c of 100 times light reduction, and a light shielding part 25d, and plays a role in adjusting the light emitted from the exit end face 24b of the optical fiber bundle 24 function of the amount of light. The focal point of the collimating lens 27 is at the position of the exit end face 24b of the fiber bundle 24, and has the function of converting the light emitted from the fiber bundle 24 into a parallel light beam.

As shown in FIG. 2 , the colored glass filter 26 plays a series of functions, for example, it has the function of correcting the sensitivity of each wavelength, and as a function of blocking the short wavelength side compared with visible light, for example, the short wavelength below the wavelength of 380nm. A cut filter for light on one side works. The transmittance of the colored glass filter 26 is set according to the wavelength.

The diffraction grating 28 functions as a wavelength splitting element that splits the light beam passing through the collimator lens 27 into wavelengths. The condensing lens 29 has a function of condensing the respective light beams separated by wavelength to the light receiving unit 4 .

As shown in FIG. 3 , the light receiving unit 4 has a rectangular shape, and has n light receiving elements such as 128, 256, 512, 1024, etc. along the lateral direction, and m light receiving elements such as 128, 256, 512 along the longitudinal direction. 1, 1024, etc. Here, the light-receiving elements 4a in the lateral direction are light-receiving elements arranged in a constant direction corresponding to the positions of the predetermined wavelengths of the split light rays. The vertical light receiving elements 4a are gathered together to form one line (1 line), and the output of each line corresponding to the position of each wavelength is input to the arithmetic circuit 6 through the A/D converter 12 . The light receiving unit 4 (light receiving element) includes a light receiving element arranged at a position corresponding to the short-wavelength light rays blocked by the colored glass filter 26 . For example, in Fig. 3, there are light-receiving elements 4a of four lines, and the light-receiving elements 4a of the four lines are disposed at positions corresponding to light rays on the short-wavelength side with a wavelength below 380nm, and are disposed at positions corresponding to the light from the colored light source. The output generated by each line of the light receiving element 4a at the position corresponding to the light on the short-wavelength side blocked by the glass filter 26 is used as a dark current output.

A correction circuit 30 is provided in the arithmetic circuit 6 . The correction circuit 30 is connected to a storage unit 31 that stores the output ratio of each light receiving element 4 a at a position corresponding to the short-wavelength light rays blocked by the colored glass filter 26 . The dark current output of the light-receiving element 4a is arranged at a position corresponding to the light of each wavelength on the long-wavelength side (compared to the light on the short-wavelength side blocked by the colored glass filter 26). The ratio between the outputs of the respective light-receiving elements 4a above, and the ratio of the output obtained by measurement under the condition that the respective light-receiving elements 4a are not illuminated.

In order to make each light receiving element 4a disposed at a position corresponding to each light beam on the long wavelength side (compared to the light beam on the short wavelength side blocked by the colored glass filter 26) be positioned at a different position In the case of receiving light, for example, the light measuring device 2 is arranged in a dark room to simultaneously measure the output of each light receiving element 4 a of the light receiving unit 4 .

As shown in FIG. 4 , the dark current output of each line of each light receiving element 4 a fluctuates for each light receiving element 4 a or for each individual light receiving unit 4 . The dark current output of each of the light receiving elements 4a is obtained by measurement in advance. If the dark current output of the line of the light-receiving element 4a arranged at the position corresponding to the light on the short-wavelength side blocked by the colored glass filter 26 is taken as X ₀ , the value used for the actual photometry of visible light Among the lines of the light-receiving element 4a (i.e.: the light-receiving element 4a disposed at the position corresponding to the light of the wavelength not blocked by the colored glass filter 26), for example, the dark current output of a certain line is taken as X, Then its ratio is X/X ₀ . This numerical ratio X/X ₀ is stored in the storage unit 31 so as to correspond to each line. The correction circuit 30 obtains the dark current output of the line of each light receiving element 4 a from the numerical ratio X/X ₀ .

Here, if the photometric output from a line of a certain light-receiving element (which is represented by reference numeral 4b) at a certain measurement time is taken as y, the light-receiving element from the light-receiving element represented by reference numeral 4b at the time of this measurement is taken as y. The dark current output of the line of the line is taken as y', and the dark current output of the line of the light receiving element corresponding to the light on the short-wavelength side that is blocked during the measurement is taken as y",

The formula is recorded as y'=y”×(X/X ₀ ),

Then the correction circuit 30 calculates the corrected dark current output y' of each line of each light receiving element 4a at a certain measurement time according to the above formula, and corrects the output voltage from each light receiving element 4a by means of the dark current output y'. The light metering output y of the line, so as to calculate the precise light metering characteristics.

By performing correction in this way, accurate correction can be performed even when the dark current output of the line of each light receiving element 4 a fluctuates. In addition, accurate correction can be performed even when the dark current output fluctuates due to thermal noise.

In addition, as the dark current output X ₀ of the line of the light receiving element 4 a corresponding to the blocked short-wavelength light, an average value of dark current outputs of a plurality of lines may be used. For example, in FIG. 3, the four lines on the short wavelength side are shown as lines corresponding to the light rays of the wavelength cut off by the colored glass filter 26, but in this case, the four lines can be obtained. The sum of dark current outputs, the value obtained by dividing the sum of dark current outputs by 4 is used as the average dark current output.

In the above-described embodiments, a CCD solid-state imaging device is used as a light receiving element, but other light receiving elements such as CMOS may be used. In addition, in this embodiment, a dark current output is obtained by using a filter that cuts off wavelengths on the short-wavelength side and using a region on the short-wavelength side of the measurement wavelength, but a configuration that uses a cutoff measurement The dark current output is detected and corrected by using a filter with a wavelength on the long wavelength side (for example, a wavelength of about 780 nm or more, or a wavelength of about 830 nm or more). Furthermore, the dark current output can be detected using a bandpass filter using both the short-wavelength side and the long-wavelength side, and can be used for correction. In addition, the cut filter can also be arranged after the collimator lens.

Claims (5)

1. a light measurer is characterized in that, comprising:

The beam split light-metering optical system that light from the determination object thing is carried out beam split and carries out photometry;

The light accepting part of the light that reception is separated by wavelength by this beam split light-metering optical system;

Export the computing circuit of computing photometry characteristic according to the photometry of this light accepting part,

Described beam split light-metering optical system has:

Light from the determination object thing is transformed into the collimation lens of parallel beam;

Make the wavelength resolution element of the light beam decomposition of having passed through this collimation lens by wavelength;

Make each light beam that has decomposed by wavelength accumulate in the light collecting lens of described light accepting part respectively;

The cut-off filter of the light of short wavelength's one side is compared in obstruct with visible light,

Described light accepting part has a plurality of photo detectors that receive the light that separates by wavelength respectively,

Described a plurality of photo detector is corresponding with the position of the wavelength of the appointment of separated light and arrange along constant direction, and, described a plurality of photo detectors be arranged in by on the corresponding position of the light of short wavelength's one side of described cut-off filter obstruct,

The output that is configured in the locational photo detector corresponding with the light of short wavelength's one side that intercepts by described cut-off filter as dark current output used,

Be provided with correction circuit in described computing circuit, this correction circuit uses described dark current to export to revise and is configured in the photometry output that produces with corresponding locational each photo detector of light compared to the wavelength of long wavelength's one side of the light of short wavelength's one side that is intercepted.

2. light measurer according to claim 1 is characterized in that described cut-off filter is arranged on before the collimation lens, and this cut-off filter is the coloured glass light filter that is used for revising the susceptibility of each wavelength.

3. light measurer according to claim 1 is characterized in that described cut-off filter is arranged on after the collimation lens, and this cut-off filter is the coloured glass light filter that is used for revising the susceptibility of each wavelength.

4. light measurer according to claim 1 and 2 is characterized in that, described cut-off filter intercepts the light of wavelength below 380nm.

5. according to each described light measurer in the claim 1～3, it is characterized in that, described correction circuit is connected with storage part, this storage part is preserved following output ratio to each photo detector, that is: be configured in dark current output with the corresponding locational photo detector of light of short wavelength's one side that intercepts by described cut-off filter, and be configured in and output compared to corresponding locational each photo detector of light of each wavelength of long wavelength's one side of the light of short wavelength's one side that is intercepted, and be this each photo detector be not subjected under the situation of illumination by measure the output obtained ratio; Described correction circuit is according to above-mentioned ratio, obtains the dark current output that is configured in compared to corresponding locational each photo detector of light of each wavelength of light long wavelength one side of short wavelength's one side.

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