Spectrophotometer and detection method for full-automatic batch detection of narrowband interference filters

Abstract

The present invention relates to a spectrophotometer and a detection method for automatic batch detection of narrowband interference filters, characterized in that: an incident slit is provided on a light-shielding cover, a quartz window plate is provided at the entrance of the incident slit, a light source is provided in front of the quartz window plate, a dispersion element and an optical path are arranged side by side in the light-shielding cover, a collimating mirror is provided opposite to the dispersion element, an objective lens is provided opposite to the optical path, an exit slit is provided at the entrance of the optical path, a semi-transmissive and semi-reflective mirror and a first detector are axially arranged in sequence in the optical path, an X-direction parallel moving track is provided below the light-shielding cover, a Y-direction parallel moving track is slidably arranged thereon, a porous filter holder is slidably arranged on the Y-direction parallel moving track, a Y-axis pitching attitude control mechanism and an X-axis pitching attitude control mechanism are provided at its bottom end, and a second detector is provided at the top end of the X-axis pitching attitude control mechanism. The present invention realizes automatic detection of perpendicularity and consistency of perpendicularity.

Description

Technical Field

[0001] The present invention relates to a spectrophotometer and a detection method for automatic batch detection of narrowband interference filters. Background Art

[0002] An interference filter is an optical thin film that uses the interference principle to allow only light within a specific spectral range to pass through. It usually consists of multiple layers of thin films. There are many types of interference filters with different uses. Common interference filters are divided into two categories: cut-off filters and band-pass filters. A band-pass filter only allows light within a relatively narrow wavelength range to pass through. A common one is the Fabry-Perot type filter, which is essentially a Fabry-Perot etalon (see Fabry-Perot interferometer). The specific structure is as follows: A semi-transparent metal layer is coated on a glass substrate, then a magnesium fluoride spacer layer is coated, and then another semi-transparent metal layer is coated. The two metal layers form two parallel plates of the Fabry-Perot etalon. When the spacing between the two poles is of the same order of magnitude as the wavelength, the interference peaks of different wavelengths in the transmitted light are well separated. By using other absorption-type filters, the light that is not allowed to pass through can be filtered out, thus obtaining a band-pass filter with a narrow passband. A narrowband interference filter is a type of band-pass filter. It uses the interference of dielectric and metal multi-layers to select specific wavelengths from incident light, and its full width at half maximum (half of the peak value) is from 1 nm to 40 nm. Narrowband interference filters can replace expensive spectroscopic devices such as gratings and are widely used in optical experiments and industrial fields. However, due to the influence of various material and process factors such as coating thickness and uniformity, and the purity and transmittance of the substrate, the finished products of mass-produced narrowband interference filters will have varying degrees of differences in key indicators such as characteristic spectral lines and full width at half maximum, and some may even have unqualified phenomena such as spurious peaks. Therefore, the ex-factory inspection of products is a very important link in the production process. The existing inspection method generally uses an ultraviolet-visible spectrophotometer to perform wavelength scanning on narrowband interference filters, and judges whether they are qualified through the absorbance energy distribution. However, when loading the filter, whether the filter is perpendicular to the optical path can only be visually judged by the loading personnel. If the loading is not perpendicular, according to the interference principle, interference filters with different coating processes will cause blue shift or red shift of the characteristic spectral lines, and some will also cause measurement errors such as broadening or narrowing of the full width at half maximum. Moreover, an ultraviolet-visible spectrophotometer can only load one filter at a time, which brings great labor intensity and measurement difficulty to the detection personnel, and it is also very difficult to improve the detection efficiency. Summary of the Invention

[0003] The present invention provides a spectrophotometer and a detection method for automatic batch detection of narrowband interference filters, which automatically adjusts the angle of the filter to achieve a perpendicular effect with the optical path, eliminates the loading error, then automatically performs wavelength scanning through the spectrophotometer and issues a detection report, and finally realizes the ex-factory inspection operation of narrowband filters with high accuracy in batches.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0005] A spectrophotometer for fully automatic batch detection of narrowband interference filters, characterized in that: an incident slit is provided on one side wall of the light-shielding cover, a quartz window is provided at the entrance of the incident slit, and a light source is provided in front of the quartz window;

[0006] A dispersion element and an optical path are arranged side by side in the light-shielding cover, a collimating mirror is arranged opposite to the dispersion element, an objective lens is arranged opposite to the optical path, an exit slit is provided at the entrance of the optical path, and a semi-transparent and semi-reflective mirror and a first detector are axially arranged in sequence in the optical path;

[0007] An X-direction parallel moving track is provided below the light-shielding cover, a Y-direction parallel moving track is slidably arranged on the X-direction parallel moving track, a porous filter holder is slidably arranged on the Y-direction parallel moving track, and a plurality of filters are placed on the porous filter holder;

[0008] A Y-axis pitching attitude control mechanism and an X-axis pitching attitude control mechanism are provided at the bottom end of the X-direction parallel moving track, and a second detector is provided at the top end of the X-axis pitching attitude control mechanism;

[0009] The dispersion element, the first detector, the porous filter holder, the Y-axis pitching attitude control mechanism, the X-axis pitching attitude control mechanism and the second detector are respectively connected to the controller by signals. The controller can control the horizontal movement of the porous filter holder by receiving the signal transmitted by the second detector. The controller can control the pitching attitudes of the Y-axis pitching attitude control mechanism and the X-axis pitching attitude control mechanism by receiving the signal transmitted by the first detector, so that the filter is completely perpendicular to the optical path. The controller controls the rotation of the dispersion element for wavelength scanning.

[0010] For the spectrophotometer for fully automatic batch detection of narrowband interference filters, wherein: the light-shielding cover is made of a metal material to form a closed dark room.

[0011] For the spectrophotometer for fully automatic batch detection of narrowband interference filters, wherein: the collimating mirror is a concave spherical mirror for making the incident light into parallel light, the dispersion element is a plane reflection grating for decomposing the composite light into monochromatic light, and the objective lens is a concave spherical mirror for a focusing device, which can focus the monochromatic light obtained after spectral separation to the exit slit.

[0012] The spectrophotometer for fully automatic batch detection of narrowband interference filters, wherein: the semi-transparent and semi-reflective mirror is a semi-transparent and semi-reflective mirror with a dot matrix metal film, which can reflect the monochromatic light emitted from the exit slit onto the filter, and can also transmit the monochromatic light reflected back from the filter onto the first detector.

[0013] A detection method for a spectrophotometer for fully automatic batch detection of narrowband interference filters, characterized by comprising the following steps:

[0014] Step 1: Start the light source. The continuous spectrum emitted by the light source is scattered in the form of a point source or a columnar source. The continuous spectrum enters the light-shielding cover through a quartz window and an entrance slit.

[0015] Step 2: The continuous spectrum is converged into parallel light by a collimating mirror and reflected onto a dispersion element. The parallel light is dispersed into monochromatic light by the dispersion element. The dispersion element reflects the monochromatic light onto an objective lens. The objective lens converges and reflects the monochromatic light onto a semi-transparent and semi-reflective mirror. After being reflected by the semi-transparent and semi-reflective mirror, the monochromatic light vertically enters the optical path, and the planar monochromatic light path is converted into a three-dimensional stereoscopic light path during the above process.

[0016] Step 3: The controller controls the movement of the multi-hole filter fixture to move the filter to the detection light path below the optical path. Most of the monochromatic light passes through the filter and is transmitted onto the second detector. The second detector transmits the signal to the control center. The controller controls the multi-hole filter fixture to stop moving, and the second detector performs spectral bandwidth scanning.

[0017] Step 4: After a small part of the monochromatic light is reflected by the filter, the monochromatic light is reflected onto the semi-transparent and semi-reflective mirror through the optical path. The monochromatic light is then transmitted through the semi-transparent and semi-reflective mirror and imaged on the first detector. The first detector performs positioning calculation on the monochromatic light, and then transmits the signal of the deviation degree of the positioning position to the controller. The control adjusts the pitching attitude through the Y-axis pitching attitude control mechanism and the X-axis pitching attitude control mechanism. After the filter is completely perpendicular to the detection light path, the controller controls the Y-axis pitching attitude control mechanism and the X-axis pitching attitude control mechanism to stop moving and maintain the perpendicular state.

[0018] Step 5: The controller performs wavelength scanning by rotating the dispersion element, and the second detector detects the absorbance of the filter, and then draws a spectrum diagram and calculates the characteristic spectral line and the full width at half maximum, and finally issues a detection report. According to the above steps, the filters on the multi-hole filter fixture are detected in sequence.

[0019] Advantages of the present invention: By using a semi-transparent and semi-reflective mirror, the planar two-dimensional optical path of the spectrophotometer is converted into a three-dimensional stereoscopic optical path, which is conducive to horizontally placing the filter to be measured by gravity, reducing the difficulty of clamping the filter; by using precise positioning, multiple filters can be clamped in batches at one time for fully automatic batch detection, improving the detection efficiency; by using pitch attitude control, the pitch attitude of the filter in the horizontal direction is automatically adjusted to eliminate the perpendicularity error and improve the measurement accuracy; by using the transmission function of the semi-transparent and semi-reflective mirror, the automatic detection of perpendicularity is realized, improving the consistency of perpendicularity. Description of the Drawings

[0020] Figure 1 It is a top view structure diagram of the interior of the light-shielding cover.

[0021] Figure 2 It is a side view structure diagram of the spectrophotometer.

[0022] Figure 3 It is a top view structure diagram of the parallel movement and pitch attitude control mechanism of the spectrophotometer.

[0023] Description of the reference numerals: 1 - light source; 2 - quartz window pane; 3 - entrance slit; 4 - collimating mirror; 5 - dispersive element; 6 - objective lens; 7 - exit slit; 8 - light-shielding cover; 9 - semi-transparent and semi-reflective mirror; 10 - optical path passage; 11 - first detector; 12 - multi-hole filter fixture; 13 - Y-direction parallel movement track; 14 - X-direction parallel movement track; 15 - Y-axis pitch attitude control mechanism; 16 - X-axis pitch attitude control mechanism; 17 - second detector; 18 - filter. Detailed Embodiments

[0024] As Figures 1 to 3 shown, the present invention provides a spectrophotometer for fully automatic batch detection of narrowband interference filters. Among them, the light-shielding cover 8 is made of a metal material to form a sealed darkroom. An entrance slit 3 is provided on one side wall of the light-shielding cover 8. A quartz window pane 2 is provided at the entrance of the entrance slit 3, and a light source 1 is provided in front of the quartz window pane 2.

[0025] A dispersion element 5 and an optical path 10 are arranged side by side in the light-shielding cover 8. The dispersion element 5 is a planar reflection grating for decomposing composite light into monochromatic light. A collimating mirror 4 is arranged opposite to the dispersion element 5. The collimating mirror 4 is a concave spherical reflecting mirror for making incident light into parallel light. An objective lens 6 is arranged opposite to the optical path 10. An exit slit 7 is arranged at the entrance of the optical path 10. The objective lens 6 is a concave spherical reflecting mirror for being a focusing device, which can focus the monochromatic light obtained after spectroscopy onto the exit slit 7. A semi-transparent and semi-reflecting mirror 9 and a first detector 11 are arranged axially in sequence in the optical path 10. The semi-transparent and semi-reflecting mirror 9 is a semi-transparent and semi-reflecting mirror with a dot matrix metal film. The semi-transparent and semi-reflecting mirror 9 can reflect the monochromatic light emitted from the exit slit 7 onto the filter 18, and the semi-transparent and semi-reflecting mirror 9 can also transmit the monochromatic light reflected back from the filter 18 onto the first detector 11.

[0026] An X-direction parallel moving track 14 is arranged below the light-shielding cover 8. A Y-direction parallel moving track 13 is slidably arranged on the X-direction parallel moving track 14. A porous filter holder 12 is slidably arranged on the Y-direction parallel moving track 13. A plurality of the filters 18 are placed on the porous filter holder 12. A Y-axis pitching attitude control mechanism 15 and an X-axis pitching attitude control mechanism 16 are arranged at the bottom end of the X-direction parallel moving track 14. A second detector 17 is arranged at the top end of the X-axis pitching attitude control mechanism 16.

[0027] The dispersion element 5, the first detector 11, the porous filter holder 12, the Y-axis pitching attitude control mechanism 15, the X-axis pitching attitude control mechanism 16 and the second detector 17 are respectively connected to a controller (not shown in the figure) in signal. By receiving the signal transmitted by the second detector 17, the controller can control the horizontal movement of the porous filter holder 12. By receiving the signal transmitted by the first detector 11, the controller can control the pitching attitudes of the Y-axis pitching attitude control mechanism 15 and the X-axis pitching attitude control mechanism 16 to make the filter 18 perpendicular to the optical path 10 completely. By controlling the rotation of the dispersion element 5, the controller performs wavelength scanning.

[0028] A detection method for a spectrophotometer for full-automatic batch detection of narrowband interference filters is characterized by comprising the following steps:

[0029] Step 1: Start the light source 1. The continuous spectrum emitted by the light source 1 is scattered in a point light source or columnar light source shape. The continuous spectrum enters the light-shielding cover 8 through the quartz window 2 and the entrance slit 3.

[0030] Step 2: The continuous spectrum is converged into parallel light by a collimating mirror 4 and reflected onto a dispersive element 5. The parallel light is dispersed into monochromatic light by the dispersive element 5. The dispersive element 5 reflects the monochromatic light to an objective lens 6. The objective lens 6 converges and reflects the monochromatic light to a semi-transmissive and semi-reflective mirror 9. After being reflected by the semi-transmissive and semi-reflective mirror 9, the monochromatic light vertically enters an optical path 10. In the above process, a planar monochromatic light path is converted into a three-dimensional stereoscopic light path;

[0031] Step 3: The controller controls the movement of a porous filter holder 12 to move the filter 18 to the detection light path below the optical path 10. Most of the monochromatic light passes through the filter 18 and is transmitted onto a second detector 17. The second detector 17 transmits a signal to the control center. The controller controls the porous filter holder 12 to stop moving, and the second detector 17 performs a spectral bandwidth scan.

[0032] Step 4: After a small part of the monochromatic light is reflected by the filter 18, the monochromatic light is reflected by the optical path 10 to the semi-transmissive and semi-reflective mirror 9. The monochromatic light is then transmitted through the semi-transmissive and semi-reflective mirror 9 and imaged onto a first detector 11. The first detector 11 performs positioning calculation on the monochromatic light and then transmits a signal of the deviation degree of the positioning position to the controller. The control adjusts the pitching attitude through a Y-axis pitching attitude control mechanism 15 and an X-axis pitching attitude control mechanism 16. After the filter 18 is completely perpendicular to the detection light path, the controller controls the Y-axis pitching attitude control mechanism 15 and the X-axis pitching attitude control mechanism 16 to stop moving and maintain a vertical state;

[0033] Step 5: The controller performs wavelength scanning by rotating the dispersive element 5, and the second detector 17 detects the absorbance of the filter 18, thereby plotting a spectrum and calculating characteristic spectral lines and the full width at half maximum, and finally issuing a detection report. According to the above steps, the filters 18 on the porous filter holder 12 are sequentially detected.

[0034] Advantages of the present invention:

[0035] Using a semi-transmissive and semi-reflective mirror to convert the planar two-dimensional light path of a spectrophotometer into a three-dimensional stereoscopic light path is beneficial to horizontally placing the filter to be measured by gravity, reducing the difficulty of loading the filter; using precise positioning to achieve automatic batch detection of multiple filters in one-time batch loading, improving the detection efficiency; using pitching attitude control to achieve automatic adjustment of the pitching attitude of the filter in the horizontal direction, eliminating the perpendicularity error, and improving the measurement accuracy; using the transmission function of the semi-transmissive and semi-reflective mirror to achieve automatic detection of perpendicularity, improving the consistency of perpendicularity.

[0036] The above description is illustrative rather than restrictive to the present invention. Those of ordinary skill in the art understand that without departing from the spirit and scope defined by the claims, many modifications, variations or equivalents can be made, but all of them will fall within the protection scope of the present invention.

Claims

1. A spectrophotometer for fully automatic batch detection of narrowband interference filters, characterized in that: An incident slit (3) is provided on one side wall of the light-shielding cover (8), a quartz window plate (2) is provided at the entrance of the incident slit (3), and a light source (1) is provided in front of the quartz window plate (2); A dispersion element (5) and an optical path (10) are arranged side by side in the light-shielding cover (8), a collimating mirror (4) is provided opposite to the dispersion element (5), an objective lens (6) is provided opposite to the optical path (10), an exit slit (7) is provided at the entrance of the optical path (10), and a semi-transparent semi-reflective mirror (9) and a first detector (11) are axially arranged in sequence in the optical path (10); An X-direction parallel moving track (14) is provided below the light-shielding cover (8), a Y-direction parallel moving track (13) is slidably arranged on the X-direction parallel moving track (14), a porous filter holder (12) is slidably arranged on the Y-direction parallel moving track (13), and a plurality of filters (18) are placed on the porous filter holder (12); A Y-axis pitching attitude control mechanism (15) and an X-axis pitching attitude control mechanism (16) are provided at the bottom end of the X-direction parallel moving track (14), and a second detector (17) is provided at the top end of the X-axis pitching attitude control mechanism (16); The dispersion element (5), the first detector (11), the porous filter holder (12), the Y-axis pitching attitude control mechanism (15), the X-axis pitching attitude control mechanism (16) and the second detector (17) are respectively connected to the controller by signals. The controller can control the horizontal movement of the porous filter holder (12) by receiving the signal transmitted by the second detector (17). The controller can control the pitching attitudes of the Y-axis pitching attitude control mechanism (15) and the X-axis pitching attitude control mechanism (16) by receiving the signal transmitted by the first detector (11), so that the filter (18) is completely perpendicular to the optical path (10). The controller can control the rotation of the dispersion element (5) for wavelength scanning.

2. The spectrophotometer for fully automatic batch detection of narrowband interference filters according to claim 1, characterized in that: The light-shielding cover (8) is made of a metal material to form a sealed darkroom.

3. The spectrophotometer for fully automatic batch detection of narrowband interference filters according to claim 1, characterized in that: The collimating mirror (4) is a concave spherical mirror for making incident light into parallel light. The dispersion element (5) is a plane reflection grating for decomposing composite light into monochromatic light. The objective lens (6) is a concave spherical mirror for a focusing device, which can focus the monochromatic light obtained after spectroscopy to the exit slit (7).

4. The spectrophotometer for fully automatic batch detection of narrowband interference filters according to claim 1, characterized in that: The semi-transmissive and semi-reflective mirror (9) is a semi-transmissive and semi-reflective mirror with a dot matrix metal film. The semi-transmissive and semi-reflective mirror (9) can reflect the monochromatic light emitted from the exit slit (7) onto the filter (18). The semi-transmissive and semi-reflective mirror (9) can also transmit the monochromatic light reflected from the filter (18) onto the first detector (11).

5. A detection method of a spectrophotometer for automatic batch detection of narrowband interference filters, which uses the spectrophotometer for automatic batch detection of narrowband interference filters as described in any one of claims 1-4, characterized in that, it includes the following steps: Step 1: Start the light source (1). The continuous spectrum emitted by the light source (1) is scattered in the form of a point light source or a columnar light source. The continuous spectrum enters the light-shielding cover (8) through the quartz window plate (2) and the entrance slit (3). Step 2: The continuous spectrum is converged into parallel light by the collimating mirror (4) and reflected onto the dispersive element (5). The parallel light is dispersed into monochromatic light by the dispersive element (5). The dispersive element (5) reflects the monochromatic light to the objective lens (6). The objective lens (6) converges and reflects the monochromatic light onto the semi-transmissive and semi-reflective mirror (9). After being reflected by the semi-transmissive and semi-reflective mirror (9), the monochromatic light vertically enters the optical path (10). In the above process, the planar monochromatic light path is converted into a three-dimensional stereoscopic light path. Step 3: The controller controls the movement of the porous filter holder (12) to move the filter (18) to the detection light path below the optical path (10). Most of the monochromatic light passes through the filter (18) and is transmitted onto the second detector (17). The second detector (17) transmits the signal to the controller. The controller controls the porous filter holder (12) to stop moving. The second detector (17) performs a spectral bandwidth scan. Step 4: After a small part of the monochromatic light is reflected by the filter (18), the monochromatic light is reflected by the optical path (10) onto the semi-transmissive and semi-reflective mirror (9). The monochromatic light is then transmitted through the semi-transmissive and semi-reflective mirror (9) onto the first detector (11) for imaging. The first detector (11) performs positioning calculation on the monochromatic light and then transmits the signal of the deviation degree of the positioning position to the controller. The controller adjusts the pitching attitude by controlling the Y-axis pitching attitude control mechanism (15) and the X-axis pitching attitude control mechanism (16). After the filter (18) is completely perpendicular to the detection light path, the controller controls the Y-axis pitching attitude control mechanism (15) and the X-axis pitching attitude control mechanism (16) to stop moving and maintain the vertical state. Step 5: The controller performs wavelength scanning by rotating the dispersive element (5), and the second detector (17) detects the absorbance of the filter (18), thereby plotting a spectrum and calculating the characteristic spectral line and the full width at half maximum. Finally, a detection report is issued. According to the above steps, the filters (18) on the porous filter holder (12) are detected in sequence.

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