TW202141030A - Method for measuring light transmittance capable of obtaining the accurate light transmittance - Google Patents

Abstract

A method for measuring light transmittance comprises the following steps of: enabling the light of the main light source to be incident from the first light entrance of the integrating sphere, and measuring the first incident light flux passing through the light exit of the integrating sphere; enabling the light of the calibration light source to be incident from the second light entrance of the integrating sphere, and measuring the first calibrated light flux passing through the light exit; placing the sample under test on the outside of the first light entrance and measuring the second calibrated light flux passing through the light exit; enabling the light of the main light source to be incident from the first light entrance through the sample under test, and measuring the second incident light flux passing through the light exit; and obtaining a calibration coefficient according to the first calibrated light flux and the second calibrated light flux, then multiplying the ratio of the second incident light flux to the first incident light flux by the calibration coefficient to obtain the light transmittance. Accordingly, the accurate light transmittance can be obtained.

Description

Measuring method of light transmittance

The present invention is related to the measurement of light transmittance; in particular, it refers to a method for measuring light transmittance using an integrating sphere.

Figure 1 shows a conventional light transmittance measurement system 100, which includes an integrating sphere 101, a light source 102, and a light measuring device 103. The integrating sphere 101 has a light entrance 101a and a light exit 101b. The light source 102 The light from the light entrance 101a enters the integrating sphere 101, and the light measuring device 103 is connected to the light exit 101b to measure the light flux passing through the light exit 101b. The sample 104 to be tested is placed outside the light entrance 101a. The conventional calculation formula of light transmittance τ is as follows:

τ=(Фs/Фi), where Фs is the luminous flux when the sample 104 to be tested is placed, and Фi is the luminous flux when the sample 104 to be tested is not placed.

The light transmittance measured by the conventional light transmittance measuring system 100 is not accurate. The reason is that when the sample 104 to be tested is placed, part of the light reflected from the inside of the integrating sphere 101 to the light entrance port Will be reflected by the sample 104 to be tested back into the integrating sphere 101 (as shown by the dashed line in Figure 1), which will cause the luminous flux Фs to increase. Therefore, after the above calculation formula is calculated, the light transmittance τ will increase, resulting in Inaccurate light transmittance.

In view of this, the purpose of the present invention is to provide a method for measuring light transmittance, which can make the measurement of light transmittance more accurate.

In order to achieve the above objective, the present invention provides a method for measuring light transmittance, which is applied to a measuring system. The measuring system includes an integrating sphere, a main light source, a calibration light source, and a light measuring device. The ball has a first light entrance, a second light entrance, and a light exit; the measurement method includes the following steps:

A. Under the condition that the sample to be tested is not placed, perform a first incident luminous flux acquisition step and a first corrected luminous flux acquisition step, where:

The step of obtaining the first incident light flux includes: controlling the light of the calibration light source to stop entering the second light entrance, and controlling the light of the main light source to enter the integrating sphere from the first light entrance, and use the light measuring device Measuring at least one first incident light flux passing through the light exit;

The step of obtaining the first calibrated luminous flux includes: controlling the light of the main light source to stop entering the first light entrance, and controlling the light of the calibrated light source to enter the integrating sphere from the second light entrance, using the light measuring device Measuring at least one first corrected luminous flux passing through the light exit;

B. Place a sample to be tested on the outside of the first light entrance, and use the light measuring device to measure at least one second calibration luminous flux passing through the light exit;

C. Control the light of the calibration light source to stop entering the second light entrance, and control the light of the main light source to enter the integrating sphere from the first light entrance through the sample to be tested, and pass through the light measuring device. At least one second incident light flux of the light exit;

D. Obtain at least one correction coefficient according to the at least one first corrected luminous flux and the at least one second corrected luminous flux, and multiply the ratio of the at least one second incident luminous flux to the at least one first incident luminous flux by the at least one correction coefficient , To obtain at least one light transmittance of the sample to be tested.

The effect of the present invention is that the ratio of the second incident luminous flux to the first incident luminous flux can be corrected by generating a correction coefficient by the first calibrated luminous flux and the second calibrated luminous flux, so as to obtain accurate light transmittance and effectively eliminate the integral The light inside the sphere is reflected back into the integrating sphere by the sample to be tested, causing measurement errors.

In order to explain the present invention more clearly, a detailed description is given below with reference to preferred embodiments in conjunction with the drawings. Please refer to FIG. 2, which is a measurement system 1 used in the light transmittance measurement method of the first preferred embodiment of the present invention. The measurement system 1 includes an integrating sphere 10, a main light source 20, and a calibration light source 30. , A light measuring device 40 and a processing device 50.

The integrating sphere 10 has a first light entrance 12, a second light entrance 14 and a light exit 16, wherein the main light source 20 faces the first light entrance 12, and the first light entrance 12 The outer side is for placing the sample 60 to be tested, and the calibration light source 30 faces the second light entrance 14. The main light source 20 includes a first light generator 22, a first collimator lens 24, and a first baffle 26. The first light generator 22 is used to generate light in a predetermined wavelength range, such as 200 to 1700 nm. The light within a range is emitted through the first collimator lens 24, and the first baffle 26 can be controlled to block the light or move the light path to let the light pass. The calibration light source 30 includes a second light generator 32, a second collimator lens 34, and a second baffle 36. The aforementioned components are the same as the main light source 20, and will not be repeated. The calibration light source 30 can be fixed on the integrating sphere 10. The optical measuring device 40 includes a spectroradiometer 42, and the spectroradiometer 42 is connected to the light exit 16 through an optical fiber 44, but it is not limited to this, and the spectroradiometer 42 can also be directly connected to the light exit 16. The spectrometer 42 is used to measure the luminous flux passing through the light exit 16 and can analyze the luminous flux of light corresponding to different wavelengths in the wavelength range of 200 to 1700 nm. The processing device 50 is electrically connected to the main light source 20, the calibration light source 30, and the spectrometer 42 to control whether the main light source 20 and the calibration light source 30 emit light. For example, it can control the first baffle 26 and the second stop. Whether the board 36 blocks light, and receives the data of the luminous flux measured by the spectrometer 42 for processing.

The light transmittance measurement method of this embodiment can be performed by the above-mentioned structure, and the method includes the following steps shown in FIG. 3, wherein:

Step S01: Under the condition that the sample 60 to be tested is not placed, perform a first incident luminous flux obtaining step and a first corrected luminous flux obtaining step, wherein:

The step of obtaining the first incident light flux includes: controlling the light of the calibration light source 30 to stop entering the second light entrance 14 and controlling the light of the main light source 20 to enter the integrating sphere 10 from the first light entrance 12, The light measuring device 40 is used to measure a first incident light flux passing through the light outlet 16. The processing device 50 obtains the first incident light flux. In this embodiment, the incident angle of the light from the main light source 20 to the first light entrance 12 is taken as an example of 0 degrees. The incident angle can also be selected as required. The aforementioned definition of the incident angle refers to the incident light and the first An included angle of the normal to the light entrance 12.

The step of obtaining the first corrected luminous flux includes: controlling the light of the main light source 20 to stop entering the first light entrance 12, and controlling the light of the corrected light source 30 to enter the integrating sphere 10 from the second light entrance 14; The light measuring device 40 is used to measure a first corrected light flux passing through the light outlet 16. The processing device 50 obtains the first corrected luminous flux. In this embodiment, part of the light reflected inside the integrating sphere 10 will pass through the first light entrance 12 to the outside of the integrating sphere 10.

The sequence of the first incident light flux obtaining step and the first corrected light flux obtaining step can be interchanged, and the sequence listed above is not limited.

Step S02: Place the sample 60 to be tested on the outside of the first light entrance 12, and measure a second calibrated luminous flux passing through the light exit 16 with the light measuring device 40. The processing device 50 obtains the second corrected luminous flux. In this embodiment, part of the reflected light inside the integrating sphere 10 will pass through the first light entrance 12 to the outside of the integrating sphere, and part of the transmitted light will be reflected back to the integrating sphere by the sample 60 under test. Internally, therefore, the measured second corrected luminous flux is greater than the first corrected luminous flux.

Step S03: Control the light of the calibration light source 30 to stop entering the second light entrance 14, and control the light of the main light source 20 to enter the integrating sphere 10 from the first light entrance 12 through the sample 60 to be tested, The light measuring device 40 is used to measure a second incident light flux passing through the light outlet 16. The processing device 50 obtains the second incident light flux. In this embodiment, the incident angle of the light from the main light source 20 to the first light entrance 12 is the same as the incident angle in the first incident light flux obtaining step of the step S01. Part of the reflected light inside the integrating sphere 10 will pass through the first light entrance 12 to the outside of the integrating sphere, and part of the transmitted light will be reflected back into the integrating sphere by the sample 60 to be tested.

Since the light of the main light source 20 and the calibration light source 30 in this embodiment covers the predetermined wavelength range (200~1700 nm), and because the spectrometer 42 is used to measure the luminous flux, the processing device 50 can be based on the measurement result of the spectrometer 42 Obtain the first corrected luminous flux, the second corrected luminous flux, the first incident luminous flux, and the second incident luminous flux corresponding to a plurality of different wavelengths, and define the first calibrated luminous flux at each wavelength as Фcs(λ) and the second calibrated luminous flux as Фcal(λ ), the first incident light flux is Фi(λ) and the second incident light flux is Фs(λ), where λ is a specific wavelength.

Step S04: The processing device 50 obtains a correction coefficient according to the first corrected luminous flux and the second corrected luminous flux, the correction coefficient is represented by k, and the ratio of the second incident luminous flux to the first incident luminous flux is multiplied by the correction coefficient, In order to obtain a light transmittance of the sample 60 to be tested. The correction coefficient is the ratio of the first corrected luminous flux to the second corrected luminous flux.

In this embodiment, the processing device 50 generates a correction coefficient k(λ) corresponding to each wavelength according to the first corrected light flux Фcs(λ) and the second corrected light flux Фcal(λ) corresponding to each wavelength, and will correspond to each wavelength The ratio of the second incident luminous flux Фs(λ) to the first incident luminous flux Фi(λ) is multiplied by the correction coefficient k(λ) corresponding to each wavelength to obtain the light transmittance τ(λ) corresponding to each wavelength. The calculation formula is as follows

τ(λ)=[Фs(λ)/Фi(λ)]×k(λ), where k(λ)=Фcs(λ)/Фcal(λ).

The calculation formula for each wavelength is the same. Therefore, the processing device 50 uses the measurement result of the spectrometer 42 to obtain the light transmittance τ(λ) of a plurality of wavelengths.

If you want to measure the light transmittance of another sample 60 to be tested at the same incident angle, perform step S02 to step S04 again, and replace the original sample 60 to be tested with another sample to be tested, so that you can get The light transmittance of another sample to be tested.

Fig. 4 is a graph showing the light transmittance curves of the measurement method of the present invention and the conventional measurement method at different wavelengths, in which the optical transmittance of the first sample and the second sample to be tested are measured respectively, because the measurement method of the present invention uses calibration The light source 30 also obtains the correction coefficient, therefore, the error of the light reflected back to the integrating sphere by the sample to be tested is effectively corrected, and the light transmittance can be accurately obtained.

Fig. 5 is a measurement system 2 used in the light transmittance measurement method of the second preferred embodiment of the present invention. The measurement system 2 is based on the first embodiment and further includes a rotating guide 70, the main The light source 20 is disposed on the rotating guide 70, and the main light source 20 can be controlled to move along the rotating guide 70, so as to change the light from the main light source 20 to enter the first entrance at different angles of incidence. Light port 12. The movement mode of the main light source 20 may be manually controlled movement, or controlled movement through a driving member such as a motor.

The measurement method of this embodiment has roughly the same steps as those of the first embodiment, but the difference is:

In step S01, the first incident light flux obtaining step is executed multiple times, and the light of the main light source 20 is controlled to be incident from the first light entrance port 12 at a different incident angle during each first incident light flux obtaining step. In the integrating sphere 10, a plurality of first incident light fluxes corresponding to different incident angles are obtained. The processing device 50 stores the angles of the incident angles and the corresponding first incident light fluxes in a storage device 80.

In step S03, the light from the main light source 20 is controlled to enter the integrating sphere 10 from the first light entrance 12 through the sample to be tested at a predetermined incident angle, so as to measure the second light source corresponding to the predetermined incident angle. Incident luminous flux. In this embodiment, the rotation angle of the main light source 20 along the rotation guide 70 is controlled to achieve the predetermined incident angle.

In step S04, the processing device 50 generates a correction coefficient corresponding to the predetermined incident angle according to the first corrected luminous flux and the second corrected luminous flux corresponding to the predetermined incident angle, and compares the second incident luminous flux corresponding to the predetermined incident angle with the first incident angle. The ratio of luminous flux is multiplied by the correction coefficient corresponding to the predetermined incident angle to obtain the light transmittance corresponding to the predetermined incident angle. In this embodiment, since the predetermined incident angle is known, the processing device 50 can obtain the first incident light flux corresponding to the predetermined incident angle from the storage device for calculating the correction coefficient.

Since a spectrometer is used, in the first incident luminous flux obtaining step of step S01, the first incident luminous flux at each incident angle may include the first incident luminous flux of multiple wavelengths. The light transmittance of the predetermined incident angle obtained in step S04 includes the light transmittance of multiple wavelengths.

The optical measurement device 40 of the aforementioned measurement systems uses a spectrometer 42 as an example. In other embodiments, the optical measurement device 40 may also use a photometer, which measures the light intensity of the corresponding luminous flux. , That is, in steps S01 to S03, the first corrected luminous flux, the second corrected luminous flux, the first incident luminous flux, and the second incident luminous flux are respectively measured by the photometer. The light of the main light source 20 and the light of the correction light source 30 have the same wavelength. In this way, it is also possible to measure a light transmittance of the sample to be tested at a specific wavelength of light.

According to the above, the light transmittance measurement method of the present invention can be obtained by calibrating the ratio of the second incident luminous flux to the first incident luminous flux by generating a correction coefficient from the first calibrated luminous flux and the second calibrated luminous flux The accurate light transmittance effectively eliminates the measurement error caused by the light inside the integrating sphere being reflected back into the integrating sphere by the sample to be tested.

The above are only the preferred and feasible embodiments of the present invention. Any equivalent changes made by applying the specification of the present invention and the scope of the patent application should be included in the patent scope of the present invention.

[Traditional] 100: Light transmittance measurement system 101: Integrating Sphere 101a: Light entrance 101b: light outlet 102: light source 103: Optical measuring device 104: sample to be tested [this invention] 1,2: Measuring system 10: Integrating sphere 12: The first light entrance 14: The second light entrance 16: light outlet 20: Main light source 22: The first light generator 24: The first collimator lens 26: First baffle 30: Calibrate the light source 32: The second light generator 34: The second collimator lens 36: second baffle 40: Optical measuring device 42: Spectrometer 44: Fiber 50: processing device 60: sample to be tested 70: Rotation guide 80: storage device S01~S04: steps

Figure 1 is a schematic diagram of a conventional optical transmittance measurement system. Fig. 2 is a schematic diagram of the measurement system of the first preferred embodiment of the present invention. Fig. 3 is a flow chart of the light transmittance measurement method of the above preferred embodiment. 4 is a graph showing the light transmittance curves of the light transmittance measurement method of the above preferred embodiment and the conventional measurement method at different wavelengths. Fig. 5 is a schematic diagram of a measurement system according to a second preferred embodiment of the present invention.

S01~S04: steps

Claims (8)

A method for measuring light transmittance is applied to a measuring system. The measuring system includes an integrating sphere, a main light source, a calibration light source, and a light measuring device. The integrating sphere has a first light entrance, a The second light entrance and one light exit; the measurement method includes the following steps: A. Under the condition that the sample to be tested is not placed, perform a first incident luminous flux acquisition step and a first corrected luminous flux acquisition step, where: The step of obtaining the first incident light flux includes: controlling the light of the calibration light source to stop entering the second light entrance, and controlling the light of the main light source to enter the integrating sphere from the first light entrance, and use the light measuring device Measuring at least one first incident light flux passing through the light exit; The step of obtaining the first calibrated luminous flux includes: controlling the light of the main light source to stop entering the first light entrance, and controlling the light of the calibrated light source to enter the integrating sphere from the second light entrance, using the light measuring device Measuring at least one first corrected luminous flux passing through the light exit; B. Place a sample to be tested on the outside of the first light entrance, and use the light measuring device to measure at least one second calibration luminous flux passing through the light exit; C. Control the light of the calibration light source to stop entering the second light entrance, and control the light of the main light source to enter the integrating sphere from the first light entrance through the sample to be tested, and pass through the light measuring device. At least one second incident light flux of the light exit; D. Obtain at least one correction coefficient according to the at least one first corrected luminous flux and the at least one second corrected luminous flux, and multiply the ratio of the at least one second incident luminous flux to the at least one first incident luminous flux by the at least one correction coefficient , To obtain at least one light transmittance of the sample to be tested. The method for measuring light transmittance according to claim 1, wherein the at least one correction coefficient is a ratio of the at least one first corrected luminous flux to the at least one second corrected luminous flux. The method for measuring light transmittance according to claim 2, wherein the at least one second corrected luminous flux is greater than the at least one first corrected luminous flux. The method for measuring light transmittance according to claim 1, wherein in step A and step C, the light of the main light source is incident on the first light entrance at the same incident angle. The method for measuring light transmittance according to claim 1, wherein the light measuring device includes a photometer, and the photometer is used to measure the at least one first calibrated luminous flux, the at least one second calibrated luminous flux, The at least one first incident luminous flux and the at least one second incident luminous flux; and the light of the main light source and the light of the correction light source have the same wavelength. The method for measuring light transmittance according to claim 1, wherein the light measuring device includes a spectroradiometer, and a plurality of first calibrated luminous fluxes, second calibrated luminous fluxes, and first calibrated luminous fluxes corresponding to different wavelengths are obtained by the spectroradiometer. The incident light flux and the second incident light flux; in step D, the correction coefficient corresponding to each wavelength is generated according to the first corrected light flux and the second corrected light flux corresponding to each wavelength, and the second incident light flux corresponding to each wavelength is compared with the first The ratio of the incident luminous flux is multiplied by the correction coefficient corresponding to each wavelength to obtain the light transmittance corresponding to each wavelength. According to the light transmittance measurement method of claim 1, step A includes performing the first incident light flux obtaining step a plurality of times, and controlling the light of the main light source to be different in each first incident light flux obtaining step An incident angle enters the integrating sphere from the first light entrance port to obtain a plurality of first incident light fluxes corresponding to different incident angles; In step C, the light of the main light source is controlled to enter the integrating sphere from the first light entrance through the sample to be tested at a predetermined incident angle to measure the second incident light flux corresponding to the predetermined incident angle; In step D, a correction coefficient corresponding to the predetermined incident angle is generated based on the first corrected luminous flux and the second corrected luminous flux corresponding to the predetermined incident angle, and the ratio of the second incident luminous flux to the first incident luminous flux corresponding to the predetermined incident angle is generated Multiply the correction coefficient corresponding to the predetermined incident angle to obtain the light transmittance corresponding to the predetermined incident angle. The method for measuring light transmittance according to claim 1, including performing steps B to D again, and replacing the sample to be tested with another sample to be tested, so as to obtain the at least one sample of the other sample to be tested Light transmittance.

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