CN112033648A - Cut-off depth detection method of optical filter - Google Patents

Abstract

The invention relates to a cut-off depth detection method of an optical filter, which comprises a light source, wherein light beams emitted by the light source penetrate through the optical filter to be detected, and then are received and displayed by spectral intensity detection equipment for primary detection; placing a high-concentration solution between the optical filter to be detected and the spectral intensity detection equipment, so that light beams emitted by the light source penetrate through the optical filter to be detected, penetrate through the high-concentration solution, and are received and displayed by the spectral intensity detection equipment for re-detection of spectral intensity; and comparing the re-measured spectral intensity with the initial measured spectral intensity, observing whether the specific wavelength with the obviously different spectral intensity exists, and if the specific wavelength with the obviously different spectral intensity exists, judging that the transmittance of the optical filter to be measured on the specific wavelength has a problem. The invention adopts a contrast mode, can conveniently and quickly find out the absorption problem of the optical filter on specific wavelengths, can carry out analysis and improvement more specifically after the specific wavelengths are determined, and guides the design and manufacture of the optical filter with more perfect and high quality.

Description

Filter cut-off depth detection method

technical field

The invention belongs to the technical field of testing optical properties in physical testing, and particularly relates to a method for detecting cut-off depth of an optical filter.

Background technique

Optical filter is a commonly used optical device, used to select the desired radiation band, widely used in optical equipment, such as cameras, video cameras, etc. The cut-off depth is one of the parameters for judging the quality of the filter. The larger the cut-off depth OD of the filter, the lower the transmittance and the lower the noise. More expensive.

Regarding the detection of the cut-off depth of the optical filter, there is a test method disclosed in CN 103616163 A; in ordinary project experiments, the Hamamatsu spectrometer and its supporting software are more commonly used. The terminal (usually a computer) of the supporting software displays the test result value through the terminal after being calculated and processed by the supporting software.

However, in experimental projects that use filters, the characteristic curve of the filter may be different due to the quality of the filter. For example, some filters need to absorb at specific wavelengths. However, there is a certain low light leakage (high transmittance); and the current method to detect the cut-off depth of the filter is not convenient to find the filter due to its own structural reasons (such as lack of design or manufacturing problems). The absorption problem (large transmittance) of one or some (not designed to pass) specific wavelengths is not convenient to guide the design of a more perfect filter, and it is not convenient to feedback to improve the quality of the filter.

SUMMARY OF THE INVENTION

In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to provide a method for detecting the cut-off depth of an optical filter, which avoids the problem of inconvenient detection of the transmittance of some specific wavelengths by the optical filter, and makes it easy to find the filter. On which specific wavelengths the film has absorption problems, it is easy to judge and feedback to improve the quality.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions:

The cut-off depth detection method of the optical filter includes a light source, and after the light beam emitted from the light source passes through the optical filter to be measured, the spectral intensity detection device receives and displays the initial measured spectral intensity; A high-concentration solution is placed in between, so that the light beam emitted by the light source passes through the filter to be measured, then passes through the high-concentration solution, and is then received by the spectral intensity detection device and displays the re-measured spectral intensity; the re-measured spectral intensity and Compare the initial measured spectral intensities, and observe whether there is a specific wavelength with a significant difference in spectral intensity. If there is a specific wavelength with a significant difference in spectral intensity, it is determined that there is a problem with the transmittance of the filter to be tested at the specific wavelength.

To further improve the above technical solution, the concentration of the high-concentration solution is greater than 30 mg/l, and the solution components include sodium oxalate, potassium permanganate, potassium hydrogen phthalate and/or ammonia nitrogen solution.

Further, the obvious difference in the spectral intensity is that the re-measured spectral intensity has a significant increase in spectral intensity compared with the initial measured spectral intensity.

Further, the filter to be tested and the high-concentration solution are placed in an integrated detection device, the integrated detection device includes a box body, and the box body is provided with a filter clamp for detachably clamping the to-be-detected. filter, the filter to be tested is clamped and fixed on the filter holder, the box is provided with a cuvette, the high-concentration solution is contained in the cuvette, and the two opposite side walls of the box are The light entrance and the light exit are respectively provided, and the light entrance and the light exit are respectively provided with a plano-convex collimating lens; the light beam emitted from the light source is incident from the convex surface of the collimating lens at the light entrance, and after collimation, passes through the lens. It passes through the filter to be tested, passes through the cuvette and the high-concentration solution in it, and then exits from the collimating lens at the light exit to the spectral intensity detection device in parallel.

Further, the cuvette is detachably fixed in the box body; the upper end of the box body is open and is equipped with a light-shielding cover plate; the light-shielding cover plate is a part of the complete detection device, and its function is to deduct dark noise and avoid experiments. The result is affected by dark noise.

Further, the spectral intensity detection device includes a spectrometer, and the spectrometer is signal-connected to a computer for processing data.

Further, an optical fiber is connected between the light source and the integrated detection device and between the integrated detection device and the spectral intensity detection device, and the corresponding light beam is conducted through the corresponding optical fiber.

Compared with the prior art, the present invention has the following beneficial effects:

1. The cut-off depth detection method of the optical filter of the present invention can easily and quickly find out which specific wavelengths the optical filter has absorption problems by using the comparison method. , which can facilitate more targeted analysis and improvement from the design and manufacturing process, so as to design and manufacture more perfect and high-quality filters.

2. In the cut-off depth detection method of the optical filter of the present invention, the design of the integrated detection device is reasonable, and the collimating lens is used to realize the collimation of the light beam emitted by the light source, so that the energy loss of the light beam is small, and the light beam can pass through the filter. The center of the filter, and then through the cuvette containing the solution, the devices used in the whole process are integrated into an overall structure, which can effectively ensure the center of the filter, the receiving end of the cuvette and the center of the collimating lens On the same horizontal line, the experimental error is minimized.

3. In the cut-off depth detection method of the optical filter of the present invention, the light beam is emitted from the integral detection device and enters the spectrometer through the optical fiber, and the result can be stored and displayed on the mobile terminal, so as to meet the current real-time and fast detection requirements for the detection process; In conclusion, the operation process of the method is simple, real-time, fast, small in error, low in cost, very implementable, and high in applicability.

Description of drawings

Fig. 1 is the structural block diagram of the cut-off depth detection method of the optical filter of the specific embodiment;

FIG. 2 is a schematic structural diagram of an integrated detection device in a specific embodiment;

Fig. 3 is the top view of Fig. 2 (for the convenience of illustration, the shading cover is hidden);

4 is a schematic diagram of the initial measurement spectral intensity in Embodiment 1;

5 is a schematic diagram of the re-measured spectral intensity in Example 1;

Fig. 6 is the schematic diagram of initial measurement spectral intensity in embodiment two;

7 is a schematic diagram of the re-measurement spectral intensity in Example 2;

Among them, the complete detection device 1 , the box body 11 , the filter holder 12 , the cuvette 13 , the light entrance 14 , the light exit 15 , the light shielding cover 16 , the filter to be tested 2 , and the solution 3 .

Detailed ways

The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

Please refer to FIGS. 1-3 . The method for detecting the cut-off depth of an optical filter according to a specific embodiment includes a conventional test process, that is, a light source is used. After the light beam emitted by the light source passes through the optical filter to be measured, it is received by a spectral intensity detection device. and display the initial measured spectral intensity; the special feature is that this embodiment adopts an integrated detection device 1 on the detection optical path. 12 is used to detachably clamp the filter to be tested 2, the filter to be tested 2 is placed in the box body 11 and clamped and fixed on the filter holder 12, and the box body 11 is also provided with The color cuvette 13, the color cuvette 13 is filled with the high-concentration solution 3, the two opposite side walls of the box body 11 are respectively provided with a light entrance port 14 and a light exit port 15, and the light entrance port 14 and the light exit port 15 are respectively A plano-convex collimating lens is provided, the convex surface of the collimating lens at the light entrance 14 faces the outside of the box body 11, the convex surface of the collimating lens at the light exit 15 faces the inside of the box body 11, and the positive surface of the filter 2 to be measured is oriented toward the inside of the box body 11. The center, the receiving end face of the cuvette 13 and the center of the collimating lens are on the same horizontal line; the light beam emitted from the light source is incident on the convex surface of the collimating lens at the light entrance 14 of the whole-installed detection device 1, and after collimation, passes through. Pass through the filter 2 to be measured, pass through the cuvette 13 and the solution 3 with the sensitive wavelength of the filter to be measured in the cuvette 13, and then exit in parallel from the collimating lens at the light outlet 15 to the spectral intensity detection device, The spectral intensity detection device receives and displays the re-measured spectral intensity. The cuvette 13 is detachably fixed in the box body 11. During the implementation, if the entire testing device 1 is used all the time during the experiment, the cuvette 13 (including the solution 3) can be taken out to obtain the initial test. Measure the spectral intensity.

Compare the re-measured spectral intensity with the initial measured spectral intensity, and observe whether there is a specific wavelength with a significant difference in spectral intensity. There is a problem with the pass rate. The problem itself is caused by the structure of the filter to be tested. Therefore, it can be further determined that the quality of the filter to be tested is not high; Therefore, it is convenient to analyze and improve in a more targeted manner from the design and manufacturing process, and design and manufacture a more complete and high-quality filter. In terms of effect, this method can also be said to be a quality inspection method for optical filters.

It should be noted that the detected specific wavelengths that have problems with the transmittance of the filter to be tested are determined by the structure (defect) of the filter to be tested, and have no corresponding relationship with the solution, but are applied on the optical path. The solution with high concentration can make the difference of spectral intensity at a specific wavelength more obvious when the re-measured spectral intensity is compared with the initial measured spectral intensity. In implementation, a high-concentration solution is preferred, and the concentration is greater than 30 mg/l. Considering the issues of environmental protection and cost, it is further preferred that the concentration of the solution is 30 mg/l to 50 mg/l.

It should be further noted that, after qualitatively judging that there is a problem with the transmittance of the filter to be tested at a specific wavelength, there is a definition or quantification of “significant difference” in the spectral intensity of the specific wavelength in the criterion before and after the comparison. The problem is that this difference is actually a standard quantity for quality inspection, which can be determined in combination with the quality requirements of the purchaser or the orderer for the filter, and even after this method can be made a testing standard, the standard inspection can be carried out. The assignment of the difference amount and the determination of the composition and concentration of the solution, in general, the smaller the amount of difference that is not allowed, the higher the quality requirements for the filter.

Of course, as common knowledge in the field, adding a solution to the light path has a certain absorption of light intensity, so the light intensity value (spectral intensity) will be attenuated, including the center wavelength. The wavelength must be significantly attenuated, that is, there is a significant difference in comparison. This is determined by the manufacturing characteristics of the filter itself, and it is not the "specific wavelength" that has obvious differences to be found. The light intensity should be attenuated. Under the common sense, the present invention refers to the obvious difference of the spectral intensity should be the obvious increase of the spectral intensity to determine the "specific wavelength". Further, it can also be taken as: if there is a specific wavelength with a significant increase in spectral intensity, and the difference between the front and back increases is not less than 50cd, it is determined that there is a problem with the transmittance of the filter to be tested at the specific wavelength.

Wherein, the solution components can be: sodium oxalate, potassium permanganate, potassium hydrogen phthalate and/or ammonia nitrogen solution.

Among them, the upper end of the box body adopts an open form, which is convenient for the removal and replacement of the filter to be tested, and the taking and placing of the cuvette and the solution. Of course, the upper end of the box body is open. Cover the upper end exposure during the experiment to ensure the implementation of the experiment process and the accuracy of the experiment.

Wherein, the spectral intensity detection device is a spectrometer, the spectrometer signal is connected to the computer that processes the data, the computer can also be connected to the storage unit and the mobile terminal by signal, the signal data received by the spectrometer can display the spectral intensity after being processed by the computer, and the computer can upload the data to It is stored in the cloud (an optional storage unit), and can be transmitted to a mobile terminal (mobile phone, laptop, etc.) for display for sharing.

The optical fiber is connected between the light source and the integrated detection device and the integrated detection device and the spectral intensity detection device. The light beam emitted by the light source enters the integrated detection device through the optical fiber, and the light beam emitted from the integrated detection device is transmitted through the optical fiber into the integrated detection device. spectrometer.

The method for detecting the cut-off depth of the optical filter provided by the present invention adopts the comparison method, which can conveniently and quickly find out which specific wavelengths the optical filter has absorption problems, and clarifies the specific wavelengths that have problems in the transmittance of the optical filter. It is convenient for more targeted analysis and improvement from the design and manufacturing process, so as to design and manufacture more perfect and high-quality filters. The integrated detection device adopted in the present invention has a reasonable design. The collimating lens is used to realize the collimation of the light beam emitted by the light source, so that the energy loss of the light beam is small. The devices used in the whole process are integrated into an overall structure, which can effectively ensure that the center of the filter, the receiving end face of the cuvette and the center of the collimating lens are on the same horizontal line, so that the experimental error is minimized ; The light beam is emitted from the whole-installed detection device and enters the spectrometer through the optical fiber, and the result can be displayed on the mobile terminal, which meets the current real-time and fast detection requirements for the detection process.

The method for detecting the cut-off depth of the optical filter provided by the invention has the advantages of simple, real-time and fast operation process, small error and low cost.

Example 1

Light source: UV-visible LED light source, which can emit near-ultraviolet beams and visible light beams in a part of the band.

Optical fiber: UV-resistant silica fiber, the wavelength range of the light source is 200nm-760nm, and the numerical aperture is NA=0.26.

Collimating Lens: Fiber-optic collimating lens, made of UV fused silica.

Filter holder: Adjustable filter holder, the clamping range is adjustable from 10-20mm.

Filter to be tested: Filter A of 214nm (center wavelength) to be tested.

Cuvette: UV resistant cuvettes.

Solution composition: solvent is water, solute is sodium oxalate and potassium permanganate (content ratio is not limited); solution concentration: 30mg/l.

First take out the cuvette (containing the solution), and detect to obtain the initial measured spectral intensity. The schematic diagram of the spectral intensity can be seen in Figure 4.

Put it into the cuvette (containing the solution), and detect and obtain the spectral intensity again. The schematic diagram of the spectral intensity can be seen in Figure 5.

Comparing the re-measured spectral intensity with the initial measured spectral intensity, it can be observed that there is absorption at a specific wavelength after passing through a high-concentration solution, and an obvious absorption peak can be observed in the spectrum. Assuming that the wavelength at which the difference in spectral intensity increases by 50 cd before and after is judged to be a specific wavelength with a significant difference, then the transmittance of the filter A to be tested at a specific wavelength of 496-518 nm has problems and needs to be improved.

Embodiment 2

The equipment and components are the same as those in the first embodiment.

Filter to be tested: Filter B of 546nm (center wavelength) to be tested.

First take out the cuvette (containing the solution), and detect to obtain the initial measured spectral intensity. The schematic diagram of the spectral intensity can be seen in Figure 6.

Put it into the cuvette (containing the solution), and detect and obtain the spectral intensity again. The schematic diagram of the spectral intensity can be seen in Figure 7.

The re-measured spectral intensity is compared with the initial measured spectral intensity, and the wavelength at which the difference before and after the spectral intensity increases to 50cd is judged as a specific wavelength with obvious difference. There was no problem in the transmittance of the sheet B at each wavelength, and the quality was good.

Embodiment 3

The equipment and components are the same as those in the first embodiment.

Solution concentration: 50mg/l.

First take out the cuvette (containing the solution), and detect to obtain the initial measured spectral intensity.

Put it into the cuvette (containing the solution), and detect to obtain the re-measured spectral intensity.

Comparing the re-measured spectral intensity with the initial measured spectral intensity, it can be observed that the spectrum has more obvious absorption peaks (the difference in the figure is not significant, and it is not shown again, you can refer to Figure 5). It is also assumed that the wavelength with the difference in the increase of spectral intensity before and after reaching 50 cd is determined as a specific wavelength with a significant difference. Then, the transmittance of the filter A to be tested at the specific wavelength of 496-518 nm still has problems.

In the existing experimental methods, different spectrometers and software can be used to obtain evidence for the judgment of the present invention, such as Shanghai Fuxiang spectrometer and supporting software.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be Modifications or equivalent substitutions without departing from the spirit and scope of the technical solutions of the present invention should be included in the scope of the claims of the present invention.

Claims (7)

1. The cut-off depth detection method of the optical filter comprises a light source, wherein light beams emitted by the light source penetrate through the optical filter to be detected, and then are received by spectral intensity detection equipment and display the primarily detected spectral intensity; the method is characterized in that: placing a high-concentration solution between the optical filter to be detected and the spectral intensity detection equipment, so that light beams emitted by the light source penetrate through the optical filter to be detected, penetrate through the high-concentration solution, and are received and displayed by the spectral intensity detection equipment for re-detection of spectral intensity;

and comparing the re-measured spectral intensity with the initial measured spectral intensity, observing whether the specific wavelength with the obviously different spectral intensity exists, and if the specific wavelength with the obviously different spectral intensity exists, judging that the transmittance of the optical filter to be measured on the specific wavelength has a problem.

2. The method of detecting the cut-off depth of the optical filter according to claim 1, wherein: the spectral intensity is significantly different, i.e. there is a significant increase in spectral intensity.

3. The method of detecting the cut-off depth of the optical filter according to claim 1, wherein: the concentration of the high-concentration solution is more than 30mg/l, and the solution components comprise sodium oxalate, potassium permanganate, potassium hydrogen phthalate and/or ammonia nitrogen solution.

4. The method of detecting the cut-off depth of the optical filter according to claim 1, wherein: the optical filter to be detected and the high-concentration solution are arranged in the integrated detection device, the integrated detection device comprises a box body, an optical filter clamp is arranged in the box body and used for detachably clamping the optical filter to be detected, the optical filter to be detected is clamped and fixed on the optical filter clamp, a cuvette is arranged in the box body, the high-concentration solution is contained in the cuvette, two opposite side walls of the box body are respectively provided with a light inlet and a light outlet, and the light inlet and the light outlet are respectively provided with a plano-convex collimating lens;

light beams emitted by the light source are incident from the convex surface of the collimating lens at the light inlet, pass through the optical filter to be detected after being collimated, penetrate through the solution in the cuvette and the cuvette, and then are emitted to the spectral intensity detection equipment in parallel from the collimating lens at the light outlet.

5. The method of detecting the cut-off depth of the optical filter according to claim 4, wherein: the cuvette is detachably fixed in the box body; the upper end of the box body is open and is provided with a shading cover plate.

6. The method of detecting the cut-off depth of the optical filter according to claim 1, wherein: the spectrum intensity detection equipment comprises a spectrometer, and the signal of the spectrometer is connected with a computer for processing data.

7. The method of detecting the cut-off depth of the optical filter according to claim 4, wherein: optical fibers are connected between the light source and the self-contained detection device and between the self-contained detection device and the spectral intensity detection equipment, and corresponding light beams are conducted through the corresponding optical fibers.

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