LIGHT RADIATION MEASUREMENT METHOD BASED ON LIGHT FILTERING UNIT AND APPARATUS THEREOF

Abstract

The present invitation relates to an optical radiation measurement method based on light filter units, comprising the steps of: 1) providing characteristic filter units and correction light filter units in front of detection units to obtain multiple measured response values of an object to be detected; and, 2) selecting one or more sampling regions within a waveband to be detected, and calculating, according to a corresponding simultaneous expression/equation system of the measured response values, a spectral power distribution within the waveband to be detected. In this method, by introducing a small number of correction light filter units, the spectral power distribution within the entire waveband to be detected can be obtained without using a large number of narrow waveband color filters. In addition, a light radiation measurement apparatus is disclosed.

Claims

1. An optical radiation measurement method based on light filter units, comprising one or more detection units n (n≧2) characteristic filter units and m (m≧2) correction filter units; the combined spectral responsivity of the detection unit and the characteristic filter units and the transmittance of the correction filter units are known; the characteristic filter units and the correction filter units are provided in front of the detection units and a plurality of measured response values of an object to be detected are obtained by a combination of the both; and, one or more sampling regions are selected within a waveband to be detected, and a spectral power distribution within the waveband to be measured is calculated according to a corresponding simultaneous equations system of the measured response values.

2. The optical radiation measurement method based on light filter units according to claim 1, characterized in that a corresponding waveband to be detected is determined by a combination of the m correction filter units and the spectral power distribution of the waveband to be detected is obtained by the following specific steps: a) acquiring a certain measured response value under a same characteristic filter unit and one or more correction filter units and acquiring n measured response values within the waveband to be detected under different characteristic filter units; and b) selecting w (1≦w≦n) sampling regions within the waveband to be detected, selecting w measured response values to establish a simultaneous equations system, and calculating the average power in the sampling regions.

3. The optical radiation measurement method based on light filter units according to claim 1, characterized in that a theoretical characteristic function corresponding to the characteristic filter units is known, and the measured response values of the detection units are corrected by the spectral power distribution: a) no any correction filter unit is placed into the light path, and a measured full-waveband response value within the whole waveband to be detected is obtained under a specified characteristic filter unit; b) under the same characteristic filter units the measured response values in different wavebands to be detected are obtained, and theoretical response values are calculated according to the spectral power distribution within correction wavebands and the corresponding theoretical characteristic functions, so that a response value deviation within each correction waveband is obtained; and c) the measured full-waveband response value is corrected by using the response value deviation in (b) to obtain a corrected full-waveband response value.

4. The optical radiation measurement method based on light filter units according to claim 1, characterized in that the measured response values of the detection units are corrected by using a spectral mismatch correction coefficient which is obtained from the spectral power distributions of the object to be detected and a calibration light source, the theoretical characteristic functions, and the combined spectral responsivity of the detection units and the characteristic filter units.

5. The optical radiation measurement method based on light filter units according to claim 1, characterized in that the waveband to be detected is a transmitted waveband of each correction filter unit within a detection waveband; or, the waveband to be detected is a waveband beyond the combined waveband of the m correction filter units within a detection waveband.

6. The optical radiation measurement method based on light filter units according to claim 3, characterized in that one or more deviation regions are contained within the detection waveband; the correction waveband is within the deviation regions, and the deviation regions are wavebands within which a direct deviation or weighted deviation between the combined spectral responsivity function of the detection units and the characteristic filter units and the corresponding theoretical characteristic function is greater than a preset value.

7. The optical radiation measurement method based on light filter units according to claim 1, characterized in that the wavebands to be detected are arranged within the detection waveband at equal central wavelength intervals.

8. The optical radiation measurement method based on light filter units according to claim 1, characterized in that the correction light units are a combination of band-pass filters and/or long-pass filters and/or short-pass filters.

9. The optical radiation measurement method based on light filter units according to claim 1, characterized in that each of the detection unit consists of one or more single-channel photoelectric detectors; or, each of the detection units is a multi-channel photoelectric detector.

10. The optical radiation measurement method based on light filter units according to claim 1, characterized in that the detection units are array detectors, and the array detectors and the characteristic filter units constitute a color CCD.

11. An optical radiation measurement apparatus for implementing claim 1, comprising one or more detection units n (n≧2) characteristic filter units and m (m≧2) correction filter units characterized in that the combined spectral responsivity of the detection units and the characteristic filter units and the transmittance of the correction filter units are known; and the characteristic filter units and the correction filter units are placed in front of the detection units, and light goes through the correction filter units and characteristic filter units and is then received by the detection units.

12. The optical radiation measurement apparatus according to claim 11, characterized in that the correction filter units are band-pass filters; or, the correction filter units are a combination of band-pass filters and/or long-pass filters and/or short-pass filters.

13. The optical radiation measurement apparatus according to claim 11, characterized in that the number m of the correction filter units satisfies the following condition: m≦10.

14. The optical radiation measurement apparatus according to claim 11, further comprising a correction wheel characterized in that the correction filter units are arranged on the correction wheel; and different correction filter units are placed into the light path in front of the detection units by rotating the correction wheel.

15. The optical radiation measurement apparatus according to claim 11, characterized in that each of the detection units consists of one or more single-channel photoelectric detectors; or, each of the detection units is a multi-channel photoelectric detector.

16. The optical radiation measurement apparatus according to claim 11, characterized in that the detection units are array detectors, and the array detectors and the characteristic filter units constitute a color CCD.

17. The optical radiation measurement apparatus according to claim 11, characterized in that each of the characteristic filter units comprises a color filter having a spectral response function of 1, i.e., a through hole.

18. The optical radiation measurement apparatus according to claim 11, characterized in that the characteristic filter units are three characteristic filter units for simulating CIE tristimulus values.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0044] To describe the technical solutions in the embodiments of the present invention or in the prior art more clearly, the accompanying drawings to be used in the descriptions of the embodiments or the prior art will be briefly described below. Apparently, the drawings described hereinafter are merely some of embodiments of the present invention, and a person of ordinary skill in the art can obtain other drawings according to these drawings without any creative effort.

[0045] FIG. 1 is a schematic diagram of a pixel response of a color CCD;

[0046] FIG. 2 is a schematic diagram of a color matching function and an actual response function of the color CCD;

[0047] FIG. 3 shows the comparison of a spectral power distribution obtained by correction filter units and an actual spectral power distribution;

[0048] FIG. 4 is a schematic diagram of an optical radiation measurement apparatus based on a light filter unit; and

[0049] FIG. 5 is a schematic diagram of correction filter units arranged on a correction wheel, in which:

[0050] 1: detection unit;

[0051] 2; characteristic filter unit;

[0052] 3: correction filter unit;

[0053] 4: correction wheel; and

[0054] 5: driving mechanism.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiment 1

[0055] This embodiment provides an optical radiation measurement method based on light filter units, including a detection unit 1, three characteristic filter units 2 and five correction filter units 3. The correction filter units 3 are band-pass filters having transmitted wavebands at an interval of 60 nm. As shown in FIG. 1, the detection unit 1 is an array detector, the array detector and the three characteristic filter units 2 constitute a color CCD, and the combined spectral response functions are R (λ), G(λ) and B (λ) , respectively.

[0056] As shown in FIG. 2, the five correction filter units 3 divide a detection waveband into 9 regions, i.e., 400nm-460nm, 460nm-480nm, 480nm-540nm, 540nm-560nm, 560nm-620nm, 620nm-640nm, 640nm-700nm and 700nm-760nm, wherein the transmitted wavebands of the correction filter units 3 are 400 nm-460 nm, 480 nm-540 nm, 560 nm-620 nm, 640 nm-700 nm and 700 nm-760 nm, respectively, and the corresponding transmittances are τ.sub.1(λ), τ.sub.2(λ), τ.sub.3(λ), τ.sub.4(λ) and τ.sub.5(λ), respectively. For the transmitted wavebands and the non-transmitted wavebands, a spectral power distribution can be obtained in the present invention, so that a spectral power distribution of the whole detection waveband can be obtained. The specific process is as follows.

[0057] For the spectral power distribution of a transmitted waveband, taking 400 nm-460 nm as example, three measured response values R.sub.1, G.sub.1 and B.sub.1 are obtained by a combination of the same correction filter units 3 having a transmittance of τ.sub.1(λ) and three characteristic filter units 2, and three sampling regions, i.e., 400 nm-420 nm, 420 nm-440 nm and 440 nm-460 nm, are selected within the waveband of 400 nm-460 nm. Then, Δλ.sub.1,Δλ.sub.2 and Δλ.sub.3 are 20 nm, P(λ.sub.1), P(λ.sub.2) and P(λ.sub.3) are the average spectral power of the wavebands 400 nm-420 nm, 420 nm-440 nm and 440 nm-460 nm, respectively, and R(λ.sub.1), G(λ.sub.1), B(λ.sub.1) are the average value of the combined spectral responsivity of the detection unit 1 and characteristic filter units 2 within the wavebands 400 nm-420 nm, 420 nm-440 nm and 440 nm-460 nm, respectively. Thus, a simultaneous equations system of three measured response values is as follows:

[00003]$\{\begin{array}{c}{R}_1=P\left({\lambda }_1\right).Math.R\left({\lambda }_1\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_1+P\left({\lambda }_2\right).Math.R\left({\lambda }_2\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_2+P\left({\lambda }_3\right).Math.R\left({\lambda }_3\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_3\\ G_1=P\left({\lambda }_1\right).Math.G\left({\lambda }_1\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_1+P\left({\lambda }_2\right).Math.G\left({\lambda }_2\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_2+P\left({\lambda }_3\right).Math.G\left({\lambda }_3\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_3\\ B_1=P\left({\lambda }_1\right).Math.B\left({\lambda }_1\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_1+P\left({\lambda }_2\right).Math.B\left({\lambda }_2\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_2+P\left({\lambda }_3\right).Math.B\left({\lambda }_3\right).Math.{\tau }_1\left(\lambda \right).Math.\Delta .Math..Math.{\lambda }_3\end{array}.$

[0058] In accordance with the equations, P(λ.sub.1), P(λ.sub.2) and P(λ.sub.3) can be calculated, that is, the average spectral power distribution corresponding to the wavebands 400 nm-420 nm, 420 nm-440 nm and 440 nm-460 nm are calculated. Similarly, under the different correction filter units 3, the spectral power distribution within the transmitted wavebands of all the correction filter units 3 are obtained.

[0059] Within the detection waveband, within the wavebands (i.e., 460 nm-480 nm, 540 nm-560 nm and 620 nm-640 nm) beyond the transmitted wavebands of the correction filter units 3, a deviation between the sum of measured response values obtained after successively placing five correction filter units 3 into the optical path and the total measured response value when the correction filter units 3 is not placed into the optical path are used as a measured response value of the wavebands, and then three measured response values are obtained under different characteristic filter units 2. The wavebands 460 nm-480 nm, 540 nm-560 nm and 620 nm-640 nm are used as sampling regions, and a simultaneous equations system of the three measured response values is as follows:

[00004]$\{\begin{array}{c}R-\underset{i=1}{\overset{5}{.Math.}}.Math.\frac{R_i}{{\tau }_i\left(\lambda \right)}=P^{\prime }\left({\lambda }_1\right).Math.R^{\prime }\left({\lambda }_1\right).Math.\Delta .Math..Math.{\lambda }_1^{\prime }+P^{\prime }\left({\lambda }_2\right).Math.R^{\prime }\left({\lambda }_2\right).Math.\Delta .Math..Math.{\lambda }_2^{\prime }+P^{\prime }\left({\lambda }_3\right).Math.R^{\prime }\left({\lambda }_3\right).Math.\Delta .Math..Math.{\lambda }_3^{\prime }\\ G-\underset{i=1}{\overset{5}{.Math.}}.Math.\frac{G_i}{{\tau }_i\left(\lambda \right)}=P^{\prime }\left({\lambda }_1\right).Math.G^{\prime }\left({\lambda }_1\right).Math.\Delta .Math..Math.{\lambda }_1^{\prime }+P^{\prime }\left({\lambda }_2\right).Math.G^{\prime }\left({\lambda }_2\right).Math.\Delta .Math..Math.{\lambda }_2^{\prime }+P^{\prime }\left({\lambda }_3\right).Math.G^{\prime }\left({\lambda }_3\right).Math.\Delta .Math..Math.{\lambda }_3^{\prime }\\ B-\underset{i=1}{\overset{5}{.Math.}}.Math.\frac{B_i}{{\tau }_i\left(\lambda \right)}=P^{\prime }\left({\lambda }_1\right).Math.B^{\prime }\left({\lambda }_1\right).Math.\Delta .Math..Math.{\lambda }_1^{\prime }+P^{\prime }\left({\lambda }_2\right).Math.B^{\prime }\left({\lambda }_2\right).Math.\Delta .Math..Math.{\lambda }_2^{\prime }+P^{\prime }\left({\lambda }_3\right).Math.B^{\prime }\left({\lambda }_3\right).Math.\Delta .Math..Math.{\lambda }_3^{\prime }\end{array}\hspace{1em}$

[0060] In accordance with the equations, the average spectral power within the wavebands 460 nm-480 nm, 540 nm-560 nm and 620 nm-640 nm is calculated, and then a spectral power distribution within the whole detection waveband can be obtained in combination with the spectral power distribution within the transmitted wavebands of each correction filter unit (3).

[0061] As shown in FIG. 3, “” denotes the average spectral power within the sampling regions, the solid line denotes the theoretical spectral power distribution. It can be seen by comparing the both that the spectral power distribution within the waveband to be detected can be accurately obtained by the optical radiation measurement method provided by the present invention, without using any devices such as a spectrometer. Similarly, the spectral power distribution within the detection waveband and beyond the transmitted wavebands can be obtained by this method, so that the spectral power distribution within the whole detection waveband is obtained.

[0062] After the spectral power distribution of the object to be obtained is obtained, the response value of the detection unit 1 (i.e., the photometric and colorimetric quantities of the object to be detected) is further corrected by using the spectral power distribution. Taking a certain characteristic filter unit 2 having a combined spectral response function R(λ) with the detection unit (1) as example, a measured response value R.sub.1 is obtained under a certain correction filter unit 3 (for example, a transmitted waveband of 400 nm-460 nm). Then, a theoretical response value R.sub.1′ of this characteristic filter unit 2 is obtained according to the theoretical characteristic function X(λ) corresponding to this characteristic filter unit 2:

R.sub.1′=R(λ.sub.1)X(λ.sub.1)τ.sub.1(λ)Δλ.sub.1+R(λ.sub.2)X(λ.sub.2)τ.sub.1(λ)Δλ.sub.2+R(λ.sub.3)X(λ.sub.3)τ.sub.1(λ)Δλ.sub.3

[0063] Thus, a response deviation of this correction filter unit is ΔR.sub.1=R.sub.1′−R.sub.1, and the total measured response value R of this characteristic filter unit 2 when no correction filter unit 3 is placed into the light path can be corrected by using the response deviation. Further, the correction can be performed in different correction filter units 3, and the corrected total measured response value R′ is obtained by using the total correction deviation:

[00005]$R^{\prime }=R+\underset{i=1}{\overset{5}{.Math.}}.Math.\Delta .Math..Math.R_1.$

[0064] Similarly, the measured response values under different characteristic filter units 2 can be corrected by the correction method to obtain accurate measured values.

TABLE-US-00001 TABLE 1 The measured response values, corrected values and theoretical values under different characteristic filter units 2 Characteristic Measured response value value Corrected value Theoretical value R 116.50 81.01 84.89 G 69.90 51.63 48.34 B 82.23 71.21 71.71

[0065] It can be seen from the table that, in comparison with the measured values, the corrected response values can accurately reflect the real theoretical response values. That is, the correction method can obtain more accurate response values.

Embodiment2

[0066] This embodiment provides an optical radiation measurement apparatus based on light filter units, including a detection unit 1, four characteristic filter units 2, five correction filter units 3, a correction wheel 4 ad a driving mechanism 5. The correction filter units 3 are band-pass filters having transmitted wavebands at an interval of 60 nm. The five correction filter units 3 are arranged on the correction wheel 4, and successively placed into the light path by the driving mechanism 5. The correction wheel 4 and the characteristic filter units 5 are successively arranged inward relative to the detection unit 1. The detection unit 1 is an array detector. The characteristic filter units 2 include three color filters and a through hole. The three color filters and the array detector constitute a color CCD, and the combined spectral response functions of the three color filters and the array detector are R(λ),G(λ) and B(λ), respectively. The characteristic filter units 2 and the correction filter units 3 are placed in front of the detection unit 1, and light goes through the correction filter units 3 and characteristic filter units 2 and is then received by the detection unit 1. A specific test method is the same as that in Embodiment 1.

[0067] The description of the embodiments described above enables those skilled in the art to implement or use the present invention. It is apparent for those skilled in the art to make various modifications to those embodiments, and the general principle defined in the present invention can be realized in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is subject to the widest scope conforming to the principle and novelty disclosed herein, rather than the embodiments described herein.