CN207050670U - A kind of Spectral Confocal measuring system caliberating device - Google Patents

Abstract

The utility model discloses a calibration device for a spectrum confocal measurement system. The device comprises a tunable laser, a double-branch optical fiber, an optical fiber exit beam, a dispersion objective lens, a dispersion objective lens exit beam, an object to be measured, a displacement platform, a displacement sensor, a spectrometer and computer. The device uses the monochromatic light with known wavelength emitted by the tunable laser as the working wavelength of the spectral confocal measurement system, measures the position information of the measured object through the displacement sensor, and uses the maximum amplitude spectral signal of the spectrometer as the basis for judgment. The displacement of the measured object, the wavelength of the laser beam emitted by the tunable laser, and the pixel number corresponding to the peak position of the spectral signal with the largest amplitude in the spectrometer, so as to establish the relationship between the pixel number and wavelength of the spectrometer and the relationship between wavelength and displacement. The requirements for the linearity of the dispersion objective lens in the spectral confocal measurement system are effectively reduced, and the measurement accuracy of the spectral confocal measurement system is improved.

Description

Calibration device for spectral confocal measurement system

technical field

The utility model relates to the technical field of optical measurement, in particular to the calibration of a spectral confocal measurement system.

Background technique

The spectral confocal method is a non-contact micro-displacement measurement method based on wavelength displacement modulation. It has the advantages of high measurement accuracy, fast speed, insensitivity to the texture and inclination of the measured surface, and no special requirements for materials. It has important application and development prospects in precision engineering such as manufacturing and ultra-precision manufacturing, micro-machines, micro- and ultra-fine processing.

There are many factors that affect the measurement accuracy of the spectral confocal system, such as the resolution of the spectrometer, the linearity of the dispersive objective lens, etc., usually need to be specially designed and individually calibrated for each factor that affects the measurement accuracy of the spectral confocal system, and the linearity of the dispersive objective lens The requirements are even more stringent. However, it is difficult to achieve ideal linear dispersion objective lens in practice. First, it is difficult to design an ideal linear dispersion objective lens in the optical design stage. Secondly, even if a dispersion objective lens with good linearity is designed, due to the dispersion objective lens Inevitable errors in the process of processing, coating, and assembly will also deteriorate the linearity of the dispersion objective lens. Therefore, how to accurately calibrate the relationship between the wavelength and displacement of the dispersive objective lens is an important guarantee for the spectral confocal measurement system to achieve high-precision measurement.

The utility model provides a calibration device and calibration method for a spectral confocal measurement system. The monochromatic light with a known wavelength emitted by a tunable laser is used as the working wavelength of the spectral confocal measurement system, and the position of the measured object is measured by a displacement sensor. Information, the maximum amplitude spectral signal of the spectrometer is used as the judgment basis, and the displacement of the measured object, the wavelength of the laser beam emitted by the tunable laser, and the pixel number corresponding to the peak position of the spectral signal with the largest amplitude in the spectrometer are obtained at the same time. Therefore, the relationship between the pixel number of the spectrometer and the wavelength and the relationship between the wavelength and the displacement are established, the strict requirement on the linearity of the dispersion objective lens is avoided, and it is beneficial to improve the measurement accuracy of the spectral confocal measurement system.

Utility model content

The purpose of this utility model is achieved through the following technical solutions.

A spectral confocal measurement system calibration device is characterized in that the device comprises a tunable laser (10), a double-branched optical fiber (20), an optical fiber exit beam (201), a dispersion objective lens (30), and a dispersion objective lens exit beam (301 ), the object to be measured (40), the displacement stage (50), the displacement sensor (60), the spectrometer (70) and the computer (80), wherein, the laser beam of the known wavelength emitted by the tunable laser (10) enters the double branch The first branch end of the optical fiber (20) is coupled into the double-branched optical fiber (20), and after being transmitted through the general end of the double-branched optical fiber (20), the optical fiber outgoing beam (201) is obtained, and the optical fiber outgoing beam (201) passes through the dispersive objective lens (30). The outgoing light beam (301) of the dispersion objective lens is obtained, and the outgoing light beam (301) of the dispersion objective lens is reflected by the object to be measured (40) and passes through the dispersion objective lens (30), the general end of the double-branched optical fiber (20), and the second end of the double-branched optical fiber (20). The branch end enters the spectrometer (70), the measured object (40) is on the displacement platform (50), a certain displacement is applied to the measured object (40) through the displacement platform (50), and the measured object is measured by the displacement sensor (60). (40), the wavelength information of the output beam of the tunable laser (10) corresponding to the displacement of the measured object (40) is obtained through the spectral signal of the spectrometer (70).

Preferably, the wavelength of the laser beam emitted by the tunable laser (10) covers the working wavelength band of the dispersive objective lens (30), and the tunable laser (10) only emits a monochromatic laser beam of a specific wavelength each time.

Preferably, the laser beam emitted by the tunable laser (10) is a continuous beam or a pulsed beam.

Preferably, when the measured object (40) has a certain displacement, the tunable laser (10) will sequentially emit monochromatic laser beams covering the working band of the dispersive objective lens (30), and when the maximum amplitude appears on the spectrometer (70), During the spectral signal, the computer (80) simultaneously records the displacement D of the measured object (40), the wavelength λ of the laser beam emitted by the tunable laser (10) and the peak value of the spectral signal with the largest amplitude in the spectrometer (70). The pixel number n corresponding to the position; the fitting of the relationship between wavelength and displacement is carried out according to the following formula,

D=C ₀ +C ₁ λ+C ₂ λ ² +...+C _m λ ^m (1) In the formula, C ₀ , C ₁ , C ₂ ,..., C _m are constants, and m is the highest power of the polynomial.

Preferably, m is determined according to the measurement accuracy requirements of the spectral confocal measurement system; the fitting residual Δ of formula (1) is

In the formula, j is the serial number, and its value is j=1, 2, ..., k, k is the number of measured wavelengths, if the fitting residual Δ is less than the specified value ε, then the value of m satisfies the spectral confocal measurement system measurement accuracy requirements.

Preferably, a corresponding relationship is established between the pixel number of the spectrometer (70) and the working wavelength of the spectral confocal measurement system, and the wavelength information in the current state is obtained by the pixel number of the spectral peak of the spectrometer (70), so that in the spectrum In the confocal measurement system, the calibration of the pixel number and the wavelength relationship of the spectrometer (70) is completed.

The calibration device of the spectral confocal measurement system provided by the utility model uses the monochromatic light with a known wavelength emitted by the tunable laser as the working wavelength of the spectral confocal measurement system, measures the position information of the measured object through the displacement sensor, and uses the spectrometer’s The maximum amplitude spectral signal is used as the basis for judgment, and the displacement of the measured object, the wavelength of the laser beam emitted by the tunable laser, and the pixel number corresponding to the peak position of the spectral signal with the largest amplitude in the spectrometer are obtained at the same time, thereby avoiding the detection of dispersion. The stringent requirements on the linearity of the objective lens are conducive to improving the measurement accuracy of the spectral confocal measurement system.

Description of drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiment. The drawings are only for the purpose of illustrating preferred embodiments, and are not considered to limit the present invention. Also throughout the drawings, the same reference numerals are used to designate the same parts. In the attached picture:

Fig. 1 is a schematic diagram of a calibration device for a spectral confocal measurement system according to an embodiment of the present invention;

Fig. 2 is a flow chart of a method for calibrating a spectral confocal measurement system according to an embodiment of the present invention;

Among them, calibration device for spectral confocal measurement system: 10. Tunable laser, 20. Dual-branch optical fiber, 201. Optical fiber exit beam, 30. Dispersion objective lens, 301. Dispersion objective lens exit beam, 40. Object to be measured, 50. Translation stage , 60, displacement sensor, 70, spectrometer, 80, computer.

detailed description

Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided in order to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

As shown in Figure 1, the schematic diagram of calibration device of spectral confocal measurement system described in the utility model, tunable laser (10), double-branch optical fiber (20), optical fiber exit beam (201), dispersion objective lens (30), dispersion objective lens Outgoing light beam (301), object to be measured (40), displacement stage (50), displacement sensor (60), spectrometer (70) and computer (80).

The laser beam of known wavelength emitted by the tunable laser (10) enters the first branch end of the double-branched optical fiber (20) and is coupled into the double-branched optical fiber (20), and is transmitted through the main end of the double-branched optical fiber (20) to obtain the output beam of the fiber (201), the optical fiber outgoing light beam (201) obtains the dispersion objective lens exit light beam (301) after passing through the dispersion objective lens (30), and the dispersion objective lens exit light beam (301) is reflected by the object to be measured (40) and passes through the dispersion objective lens (30), double The main end of the branch optical fiber (20) and the second branch end of the double-branch optical fiber (20) enter the spectrometer (70), apply a certain displacement to the measured object (40) through the displacement stage (50), and measure it through the displacement sensor (60). For the displacement of the measured object (40), the wavelength information of the output beam of the tunable laser (10) corresponding to the displacement of the measured object (40) can be obtained through the spectral signal of the spectrometer (70). By performing polynomial fitting on multiple sets of wavelengths and the displacements corresponding to the wavelengths, the relationship between the wavelength and displacement of the spectral confocal measurement system can be obtained, thereby realizing the calibration of the spectral confocal measurement system.

The wavelength of the laser beam emitted by the tunable laser (10) can cover the working band of the dispersive objective lens (30), and the tunable laser (10) only emits a monochromatic laser beam of a specific wavelength each time.

The laser beam emitted by the tunable laser (10) can be a continuous beam or a pulsed beam.

When the measured object (40) has a certain displacement, the tunable laser (10) will sequentially emit monochromatic laser beams covering the working band of the dispersive objective lens (30), when the spectral signal with the largest amplitude appears on the spectrometer (70) , the computer (80) simultaneously records the displacement D of the measured object (40), the wavelength λ of the laser beam emitted by the tunable laser (10) and the corresponding peak position of the spectral signal with the largest amplitude in the spectrometer (70) The pixel number n. The relationship between wavelength and displacement is fitted according to the following formula,

D＝C ₀ +C ₁ λ+C ₂ λ ² +…+C _m λ ^m (1)

In the formula, C ₀ , C ₁ , C ₂ ,..., C _m are constants, and m is the highest power of the polynomial.

The above m is determined according to the measurement accuracy requirements of the spectral confocal measurement system. The fitting residual Δ of formula (1) is

In the formula, j is the serial number, and its value is j=1, 2, ..., k, k is the number of measured wavelengths, if the fitting residual Δ is less than the specified value ε, then the value of m satisfies the spectral confocal measurement system measurement accuracy requirements.

Correspondence is established between the pixel number of the spectrometer (70) and the operating wavelength of the spectral confocal measurement system, and the wavelength information in the current state can be obtained by the pixel number of the spectral peak of the spectrometer (70), thereby in the spectral confocal The calibration of the pixel number and wavelength relationship of the spectrometer (70) is completed in the coke measurement system.

As shown in Figure 2, it is a flow chart of a spectral confocal measurement system calibration method described in this utility model. When the spectral confocal measurement system calibration device is used to calibrate the spectral confocal measurement system, the spectral confocal measurement system calibration The method includes the following steps:

S1, apply a certain displacement to the measured object (40) through the displacement platform (50), and record the position of the measured object (40) at this time through the displacement sensor (60);

S2, setting the output wavelength range of the tunable laser (10), so that the tunable laser (10) sequentially emits a monochromatic laser beam covering the working band of the dispersion objective lens (30);

S3, when the spectral signal with the largest amplitude appears on the spectrometer (70), simultaneously record the wavelength λ of the laser beam emitted by the tunable laser (10) and the largest spectrum in the spectrometer (70) through the computer (80) The pixel number n corresponding to the peak position of the signal;

S4. Steps S1 to S3 are repeated to obtain multiple groups of wavelengths λ and the displacement D corresponding to the wavelength and the pixel number n corresponding to the peak position of the spectral signal with the largest amplitude in the spectrometer (70) corresponding to the wavelength;

S5, establish the corresponding relationship between the spectrometer (70) pixel number n and the wavelength λ;

S6, polynomial fitting is carried out to the wavelength λ and the displacement D corresponding to the wavelength, and the relationship between the wavelength and the displacement of the measured object (40) is established,

D＝C ₀ +C ₁ λ+C ₂ λ ² +…+C _m λ ^m (1)

In the formula, C ₀ , C ₁ , C ₂ ,..., C _m are constants, m is the highest power of the polynomial, and m is determined according to the measurement accuracy requirements of the spectral confocal measurement system; among them, the formula (1) The fitting residual Δ is

In the formula, j is the serial number, and its value is j=1, 2, ..., k, k is the number of measured wavelengths, if the fitting residual Δ is less than the specified value ε, then the value of m satisfies the spectral confocal measurement system measurement accuracy requirements.

The above is only a preferred embodiment of the utility model, but the scope of protection of the utility model is not limited thereto, and any person familiar with the technical field can easily think of All changes or replacements should fall within the protection scope of the present utility model. Therefore, the protection scope of the present utility model should be based on the protection scope of the claims.

Claims (3)

1. A kind of 1. Spectral Confocal measuring system caliberating device, it is characterised in that the device include tunable laser (10), double points Branch optical fiber (20), fiber exit beam (201), dispersion object lens (30), dispersion objective lens exit light beam (301), determinand (40), position Moving stage (50), displacement transducer (60), spectrometer (70) and computer (80), wherein, tunable laser (10) is emitted Know that the first branch end of laser beam into the double branch optical fibers (20) of wavelength is coupled into double branch optical fibers (20), through double branch's light Fiber exit beam (201) is obtained after fine (20) always end transmission, fiber exit beam (201) obtains color after dispersion object lens (30) Dissipate objective lens exit light beam (301), dispersion objective lens exit light beam (301) reflected by determinand (40) after through dispersion object lens (30), double Always end, the second branch end of double branch optical fibers (20) enter spectrometer (70) to branch optical fiber (20), and measured object (40) is in displacement platform (50) on, certain displacement is applied to measured object (40) by displacement platform (50), measured object is measured by displacement transducer (60) (40) displacement, obtained by the spectral signal of spectrometer (70) tunable corresponding to the displacement of measured object (40) The wavelength information of laser (10) outgoing beam.
2. 2. a kind of Spectral Confocal measuring system caliberating device according to claim 1, it is characterised in that described tunable sharp The service band of the wavelength covering dispersion object lens (30) of light device (10) outgoing laser beams, and tunable laser (10) is each only It is emitted the one-wavelength laser light beam of specific wavelength.
3. 3. a kind of Spectral Confocal measuring system caliberating device according to claim 2, it is characterised in that described tunable sharp The laser beam of light device (10) outgoing is continuous light beam or pulsed light beam.