A fluorescence dyeing film thickness measurement system of interference-fluorescence in-situ coupling

Abstract

The application discloses a fluorescent dyeing film thickness measurement system based on in-situ coupling of interference and fluorescence, and considers the advantages of the two methods, so that the fluorescence intensity distribution and the interference fringe image of the film to be measured can be obtained in-situ based on the same light path, and then the film thickness of the micrometer level and nanometer level can be calculated by using the fluorescence method and the interference method respectively, the film thickness measurement in-situ coupling of interference and fluorescence is realized, and therefore the sensitivity of the film thickness measurement is effectively improved, and the range of the film thickness measurement is expanded.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of measurement technology, in particular to a kind of interference-fluorescence in situ coupling fluorescent dye film thickness measurement system. BACKGROUND

[0002] Optical fluorescent dye film thickness measurement technology is a kind of transparent fluorescent dye liquid or solid film thickness measurement technology based on optical method, such as measuring LED fluorescent film thickness, gap fluorescent liquid film thickness, or indirectly measuring the height of structure gap, the depth of surface groove, etc., which is applied in mechanical, electronic, biological and other industries. Interference fringe method and fluorescence method are two different principles of transparent film thickness measurement method. Among them, fluorescence method is based on laser-induced fluorescence principle, uses fluorescent agent to uniformly dye the film to be measured, uses laser to excite and obtains fluorescence image, calculates film thickness by fluorescence intensity, which is generally used for micrometer to millimeter scale film thickness measurement, and the range is large, but the sensitivity for micrometer scale film thickness measurement is poor. While interference fringe method is based on the principle of light interference, obtains the laser interference image of the film, and calculates the gap thickness by interference fringe order and relative light intensity, which is generally used for nanometer scale film thickness measurement, and the sensitivity is high, but it is not suitable for micrometer scale film thickness measurement. If fluorescence method and interference fringe method can be coupled in situ based on the same optical path, micrometer and nanometer film thickness can be measured simultaneously, so that the sensitivity of fluorescence method for micrometer scale film thickness measurement can be effectively improved, and the range of fluorescence method can be expanded. SUMMARY

[0003] Therefore, the present application provides an interference-fluorescence in situ coupling fluorescent dye film thickness measurement system, which can obtain the fluorescence intensity distribution and interference fringe image of the film to be measured in situ based on the same optical path, and then calculate the micrometer and nanometer film thickness by using fluorescence method and interference method respectively, realize interference-fluorescence in situ coupling film thickness measurement, effectively improve the sensitivity of film thickness measurement, and expand the range of film thickness measurement.

[0004] An interference-fluorescence in situ coupling fluorescent dye film thickness measurement system includes an interference-fluorescence in situ coupling main optical path and a film to be measured combination module.

[0005] The film to be measured combination module includes a gold plating film (3), a glass sheet (4), a mirror (1) and a fluorescent dye film to be measured (2). The lower surface of the glass sheet (4) is plated with a gold plating film (3). The fluorescent dye film to be measured (2) is attached below the gold plating film (3), and the emission peak wavelength is λ E . The mirror (1) is placed below the fluorescent dye film to be measured (2).

[0006] The interference-fluorescence in-situ coupling main light path comprises an objective lens (5), a first imaging lens (13), a second imaging lens (15), a fluorescence module, an optical interference module, a light splitting module, a first camera (14), a second camera (16), a first laser source (7) and a second laser source (10);

[0007] The to-be-tested thin film combination module, the objective lens (5), the fluorescence module, the interference module and the light splitting module are sequentially arranged in the main light path;

[0008] The fluorescence module comprises a two-phase color long-pass filter (17) with a threshold of λ1 and a first long-pass filter (18) with a threshold of λ2; the two-phase color long-pass filter (17) is at an angle of 45 degrees with the main light path optical axis, and the first long-pass filter (18) is placed perpendicularly to the main light path optical axis;

[0009] The optical interference module comprises a full-wavelength half-reflective half-transmissive filter (19); the full-wavelength half-reflective half-transmissive filter (19) is at an angle of 45 degrees with the main light path optical axis;

[0010] The light splitting module comprises a two-phase color short-pass filter (20) with a threshold of λ3, a short-pass filter (21) with a threshold of λ4 and a second long-pass filter (22) with a threshold of λ5; the two-phase color short-pass filter (20) is at an angle of 45 degrees with the main light path optical axis; the short-pass filter (21) is placed perpendicularly to the main light path optical axis, and the second long-pass filter (22) is parallel to the main light path optical axis;

[0011] The fluorescence module, the optical interference module and the light splitting module can be respectively moved into or out of the main light path;

[0012] The first camera (14) and the first imaging lens (13) are placed in the reflected light path of the second long-pass filter (22) and are used for interference imaging;

[0013] The second camera (16) and the second imaging lens (15) are placed in the reflected light path of the full-wavelength half-reflective half-transmissive filter (19) and are used for fluorescence imaging;

[0014] The working wavelength of the first laser source (7) is λ F , and the laser generated thereby is reflected by the two-phase color long-pass filter (17) into the main light path; the working wavelength of the second laser source (10) is λ R , and the laser generated thereby is reflected by the full-wavelength half-reflective half-transmissive filter (19) into the main light path;

[0015] The wavelength relationship satisfies the following formula:

[0016] λ F <λ1<λ2<λ E <530nm<λ4<λ3<λ5<λ R .

[0017] Preferably, λ1=490nm; λ2=500nm; λ3=625nm; λ4=600nm; λ5=630nm; λ F =470nm; λ R =655nm; λ E =515nm.

[0018] Preferably, the first camera (14) and the second camera (16) are interconnected by a synchronization signal line (23) to achieve synchronous triggering.

[0019] Preferably, the fluorescence module further includes a first lens frame (6); the dichroic long-pass filter (17) and the first long-pass filter (18) are mounted on the first lens frame (6).

[0020] Preferably, the optical interference module further includes a second mirror frame (9); the full-wavelength semi-reflective and semi-transparent filter (19) is mounted on the second mirror frame (9).

[0021] Preferably, the beam splitting module further includes a third mirror frame (12); the dichroic short-pass filter (20), the short-pass filter (21), and the second long-pass filter (22) are mounted on the third mirror (12).

[0022] The present invention has the following beneficial effects:

[0023] This invention provides an in-situ coupled fluorescence-fluorescence system for measuring the thickness of fluorescently stained thin films. Addressing the limitations of the interference fringe method for film thickness measurements above the micrometer scale and the poor sensitivity of the fluorescence method for film thickness measurements below the micrometer scale, this invention considers the advantages of both methods and uses the same optical path to measure the film thickness at the same location, thereby achieving in-situ coupling and effectively improving the sensitivity and range of film thickness measurement. Attached Figure Description

[0024] Figure 1 This is a schematic diagram illustrating the hardware system composition, imaging principle, and actual usage of the measurement method of the present invention.

[0025] Among them, 1-reflector, 2-fluorescent stained film to be tested, 3-gold coating, 4-glass slide, 5-objective lens, 6-first frame (fluorescent module), 7-first laser source (wavelength λ) F 8-First optical fiber (nm, used for interferometric imaging), 9-Second frame (interferometric module), 10-Second laser source (wavelength λ) Rnm, for fluorescence imaging), 11-second optical fiber, 12-third mirror holder (light splitting module), 13-first imaging lens (interference), 14-first camera (interference), 15-second imaging lens (fluorescence), 16-second camera (fluorescence), 17-two-color long-pass filter (threshold value λ1 nm), 18-first long-pass filter (threshold value λ2 nm), 19-full-wavelength half-reflective half-transmissive filter, 20-two-color short-pass filter (threshold value λ3 nm), 21-short-pass filter (threshold value λ4 nm), 22-second long-pass filter (threshold value λ5 nm), 23-camera synchronization signal line, and the arrow dotted line represents the light and its propagation direction. DETAILED DESCRIPTION

[0026] The present application will be described in detail below with reference to the accompanying drawings and examples.

[0027] The present embodiment provides an interference-fluorescence in-situ coupling fluorescent dye film thickness measurement system, referring to the accompanying drawings Figure 1 , comprising: an interference-fluorescence in-situ coupling main light path and a to-be-measured film combination module;

[0028] The to-be-measured film combination module comprises a gold plating film 3, a glass sheet 4, a mirror 1, and a to-be-measured fluorescent dye film 2; the glass sheet 4 is made of quartz glass, and the lower surface is plated with the gold plating film 3 which is made of high-purity gold and has a silica protective layer and a smooth surface; the to-be-measured fluorescent dye film 2 is tightly attached below the gold plating film 3 and is a film with high transparency and uniform fluorescent dye, and the fluorescent emission peak wavelength is λ E = 515 nm; the mirror surface of the mirror 1 has high reflectivity and is placed tightly below the to-be-measured fluorescent dye film 2.

[0029] The interference-fluorescence in-situ coupling main light path comprises: an objective lens 5, a first imaging lens 13, a second imaging lens 15, a fluorescence module, an interference module, a light splitting module, a first camera 14, a second camera 16, a first laser source 7, a second laser source 10, a first optical fiber 8, a second optical fiber 11, and a camera synchronization signal line 23.

[0030] The to-be-measured film combination module, the objective lens 5, the fluorescence module, the interference module, and the light splitting module are arranged in the main light path from bottom to top.

[0031] The fluorescence module comprises a two-color long-pass filter 17 with a threshold value λ1 = 490 nm, a first long-pass filter 18 with a threshold value λ2 = 500 nm, and a first mirror holder 6; the two-color long-pass filter 17 and the first long-pass filter 18 are installed on the first mirror holder 6; the two-color long-pass filter 17 is at a 45-degree angle with the main light path optical axis, and the first long-pass filter 18 is placed vertically to the main light path optical axis.

[0032] The light interference module comprises: a full-wavelength half-reflective half-transmissive filter 19, a second mirror frame 9, and the full-wavelength half-reflective half-transmissive filter 19 is installed on the second mirror frame 9 and is at an angle of 45 degrees with the main light path optical axis.

[0033] The light splitting module comprises: a two-phase color short-pass filter 20 with a threshold of λ3=625nm, a short-pass filter 21 with a threshold of λ4=600nm, a second long-pass filter 22 with a threshold of λ5=630nm, and a third mirror frame 12, the two-phase color short-pass filter 20, the short-pass filter 21 and the second long-pass filter 22 are installed on the third mirror frame 12; the two-phase color short-pass filter 20 is at an angle of 45 degrees with the main light path optical axis; the short-pass filter 21 is perpendicular to the main light path optical axis, and the second long-pass filter 22 is parallel to the main light path optical axis.

[0034] The first mirror frame 6, the second mirror frame 9 and the third mirror frame 12 can be moved in parallel, and the fluorescence module, the light interference module and the light splitting module can be moved into or out of the main light path, so that different working modes are formed according to needs.

[0035] The first camera 14 and the second camera 16 are two cameras with the same frame frequency and resolution, which can be connected with each other through a synchronization signal line 23 to realize synchronous triggering.

[0036] The first camera 14 and the first imaging lens 13 are placed in the reflection light path of the second long-pass filter 22 and are used for interference imaging.

[0037] The second camera 16 and the second imaging lens 15 are placed in the reflection light path of the full-wavelength half-reflective half-transmissive filter 19 and are used for fluorescence imaging.

[0038] The working wavelength of the first laser source 7 is λ F =470nm, which is used for fluorescence imaging, and the laser generated thereby is reflected into the main light path through the two-phase color long-pass filter 17; the working wavelength of the second laser source 10 is λ R =655nm, which is used for interference imaging and is reflected into the main light path through the full-wavelength half-reflective half-transmissive filter 19.

[0039] The laser source and each filter satisfy the following wavelength relationship:

[0040] λ F <λ1<λ2<λ E <530nm<λ4<λ3<λ5<λ R .

[0041] The specific measurement process of the application is realized through the following steps:

[0042] Step S1: The reflecting mirror 1 is placed below the fluorescent dyeing film 2 to be measured and closely adheres.

[0043] Step S2: Place the glass sheet 4 plated with the thin gold film 3 above the fluorescent dye film 2 to be measured, and tightly attach the thin gold film 3 to the fluorescent dye film 2 to be measured;

[0044] Step S3: The fluorescence module, the interference module, and the light splitting module are all in the main light path, realizing in-situ coupling measurement function of interference-fluorescence, the camera and the imaging lens are used for fluorescence imaging in one way and for interference imaging in the other way, the two cameras are connected with each other through a synchronous signal to realize synchronous triggering shooting;

[0045] Step S4: Remove the interference module and the light splitting module from the main light path to independently realize the function of laser-induced fluorescence measurement, the camera and the imaging lens are used for fluorescence imaging in one way and are idle in the other way;

[0046] Step S5: Remove the fluorescence module and the light splitting module from the main light path to independently realize the function of laser-induced fluorescence measurement, the camera and the imaging lens are used for interference imaging in one way and are idle in the other way;

[0047] Step S6: Turn on the first laser source 7, and adjust the objective lens 5 so that the laser emitted by the first laser source 7 is focused in the thin film combination module to be measured in the main light path.

[0048] Step S7: Due to the wavelength relationship, the laser can be reflected by the dichroic long-pass filter 17, transmitted through the gold plating film 3, and excite the fluorescent agent in the thin film 2 to be measured to produce fluorescence; the fluorescence can be transmitted through the gold plating film 3, the dichroic long-pass filter 17, the first long-pass filter 18, and the dichroic short-pass filter 20 and the short-pass filter 21 in the light splitting module, and finally focused on the imaging device of the second camera 16 through the second imaging lens 15.

[0049] Step S8: Use the second camera 16 to shoot a fluorescence image, and based on the gray value I f of the fluorescence image, calculate the thickness h of the thin film according to the Beer-Lambert law as follows:

[0050] h = Aln(I f +B) + C;

[0051] Wherein, A, B, and C are measurement parameters, which are obtained by testing calibration;

[0052] Step S9: turn on the second laser source 10, due to the wavelength relationship, the laser can be reflected by the full-wavelength half-reflective half-transmissive filter 19, part of the light is reflected by the gold plating film 3, and the other part of the light is reflected by the mirror 1 after transmitting through the gold plating film 3 and the measured film 2, the two parts of reflected light are enhanced or cancelled, forming interference fringes; the reflected light of the fringes transmits through the gold plating film 3 and the fluorescent module filter, transmits through the full-wavelength half-reflective half-transmissive filter 19, is reflected by the dichroic short-pass filter 20, transmits through the second long-pass filter 22, and is finally focused on the imaging device of the first camera 14 through the first imaging lens 13.

[0053] Step S10: use the first camera 14 to shoot the interference fringe image, and calculate the film thickness h based on the gray value I r of the interference fringe according to the relative light intensity theory of light interference as follows:

[0054] h = λ R [arccos((2I r -(I max +I min )) / (I max -I min ))-arccos((2I r0 -(I max +I min )) / (I max -I min ))] / (4πn)

[0055] wherein I max is the maximum gray value of the bright fringe, I min is the darkest gray value of the dark fringe, I r0 is the gray value when the thickness of the measured film is zero, and n is the refractive index of the measured film.

[0056] In summary, the above is only a preferred embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An interferometric-fluorescent in-situ coupling fluorescent dye film thickness measurement system, characterized by, The interference-fluorescence in-situ coupling main light path and the to-be-measured film combination module are included; The to-be-tested film combination module comprises a gold plating film (3), a glass sheet (4), a reflector (1) and a to-be-tested fluorescent dyeing film (2); the lower surface of the glass sheet (4) is plated with the gold plating film (3); the to-be-tested fluorescent dyeing film (2) is attached below the gold plating film (3), and the emission peak wavelength is λ E ; the reflector (1) is attached below the to-be-tested fluorescent dyeing film (2). The interference-fluorescence in-situ coupling main light path includes an objective lens (5), a first imaging lens (13), a second imaging lens (15), a fluorescence module, an optical interference module, a light splitting module, a first camera (14), a second camera (16), a first laser source (7) and a second laser source (10); The to-be-measured film combination module, the objective lens (5), the fluorescence module, the interference module and the light splitting module are sequentially arranged in the main light path. The fluorescence module includes a two-phase color long-pass filter (17) with a threshold of λ1 and a first long-pass filter (18) with a threshold of λ2; the two-phase color long-pass filter (17) is at a 45-degree angle with the main light path optical axis, and the first long-pass filter (18) is placed vertically to the main light path optical axis. The optical interference module includes a full-wavelength half-reflective half-transmissive filter (19); the full-wavelength half-reflective half-transmissive filter (19) is at a 45-degree angle with the main light path optical axis. The light splitting module includes a two-phase color short-pass filter (20) with a threshold of λ3, a short-pass filter (21) with a threshold of λ4 and a second long-pass filter (22) with a threshold of λ5; the two-phase color short-pass filter (20) is at a 45-degree angle with the main light path optical axis; the short-pass filter (21) is vertically to the main light path optical axis, and the second long-pass filter (22) is parallel to the main light path optical axis. The fluorescence module, the optical interference module and the light splitting module can be respectively moved into or out of the main light path. The first camera (14) and the first imaging lens (13) are placed in the reflection light path of the second long-pass filter (22) and are used for interference imaging. The second camera (16) and the second imaging lens (15) are placed in the reflection light path of the full-wavelength half-reflective half-transmissive filter (19) and are used for fluorescence imaging. The working wavelength of the first laser source (7) is λ F The generated laser is reflected into the main light path through a two-phase color long-pass filter (17); the working wavelength of the second laser source (10) is λ R , reflected into the main light path through a full-wavelength half-reflection half-transmission filter (19); The wavelength relationship satisfies the following formula: λ F <λ1<λ2<λ E <530nm<λ4<λ3<λ5<λ R .

2. An interferometric-fluorescent in situ coupled fluorescent dye film thickness measurement system as defined in claim 1, wherein, λ1=490nm; λ2=500nm; λ3=625nm; λ4=600nm;λ5=630nm;λ F =470nm;λ R =655nm;λ E = 515nm.

3. An interferometric-fluorescent in situ coupling fluorescent dye film thickness measurement system as defined in claim 1, wherein, The first camera (14) and the second camera (16) are connected to each other through a synchronous signal line (23) to realize synchronous triggering.

4. An interferometric-fluorescent in situ coupling fluorescent dye film thickness measurement system as defined in claim 1, wherein, The fluorescence module further includes a first mirror frame (6); the two-phase color long-pass filter (17) and the first long-pass filter (18) are installed on the first mirror frame (6).

5. An interferometric-fluorescent in situ coupling fluorescent dye film thickness measurement system as defined in claim 1, wherein, The optical interference module further includes a second mirror frame (9); the full-wavelength half-reflective half-transmissive filter (19) is installed on the second mirror frame (9).

6. An interferometric-fluorescent in situ coupling fluorescent dye film thickness measurement system as defined in claim 1, wherein, The light splitting module further includes a third mirror frame (12); the two-phase color short-pass filter (20), the short-pass filter (21) and the second long-pass filter (22) are installed on the third mirror frame (12).

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