CN111999035A - F-P filter transmission curve calibration method using frequency stabilization He-Ne laser - Google Patents

Abstract

The invention discloses a method for calibrating the transmission curve of an F-P filter using a frequency-stabilized He-Ne laser, which can very accurately calibrate the transmission curve of the F-P filter; The He-Ne laser generates a frequency-stabilized laser and expands and collimates the beam. The laser is divided into two beams by a beam splitter with a beam splitting ratio of 1:1. One beam directly enters the second CCD, and the other beam is filtered by the F-P to be calibrated. After the device is received by the first CCD, the response characteristics of the used CCD and the beam splitting ratio of the beam splitter are calibrated before the experiment. Adjust the tuning position of the F‑P filter multiple times, measure the laser output light intensity and the transmitted light power corresponding to different tuning positions at the same time, correct the measured value and calculate the transmittance using the CCD response characteristics and the spectral ratio of the beam splitter, and use the Gaussian function The relationship curve between transmittance and tuning wavelength is obtained by fitting, and the average value is obtained by repeating the measurement several times, which is the transmission curve of the F-P filter, and the main application parameters such as the half-width and peak transmittance of the filter can be calculated. .

Description

A Calibration Method of F-P Filter Transmission Curve Using Frequency Stabilized He-Ne Laser

technical field

The invention relates to a method for calibrating the transmission curve of an F-P filter, in particular to a method for calibrating the transmission curve of an F-P filter using a frequency-stabilized He-Ne laser.

Background technique

F-P filter is a filter device with excellent performance, which is mainly developed based on the principle of multi-beam interference of parallel plates, and is widely used in astronomical observation as a scanning imaging spectrometer. Before F-P is formally used in scanning imaging, its main performance parameters must be calibrated to ensure that accurate data can be obtained during imaging.

Peak transmittance and half width are the main application performance parameters of F-P. In order to accurately calibrate it, it is generally necessary to measure its transmission curve.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to propose a method for systematically calibrating the main application performance parameters of the F-P filter with high precision.

The technical solution adopted by the present invention to solve the technical problem is: a method for calibrating the transmission curve of an F-P filter using a frequency-stabilized He-Ne laser, comprising the following steps:

Step 1, using a frequency-stabilized He-Ne laser with an extremely narrow bandwidth to generate a frequency-stabilized laser and expand the beam for collimation;

Step 2, do not put the F-P filter to be calibrated, calibrate the response of the first CCD, the second CCD and the beam splitter ratio;

Step 3, using a beam splitter to divide the laser into two beams, one beam directly enters the second CCD, and the other beam is received by the first CCD after passing through the F-P filter to be calibrated;

Step 4, adjust the tuning position of the FP filter to be calibrated at a certain tuning wavelength λ _i , and simultaneously measure the laser output light power and the transmitted light power of the laser passing through the FP filter to be calibrated;

Step 5, using the response characteristics of the first CCD, the second CCD and the spectral ratio of the spectroscope to correct the measured value and calculate the transmittance;

Step 6, changing λ _i , repeating steps 4 and 5, measuring multiple sets of transmittance A-tuning wavelength λ data, fitting the curve with a Gaussian function, and calculating the half-width of the curve and the peak transmittance.

The beneficial effects of the present invention compared with the prior art are:

(1) The experimental device and operation of the calibration method of the F-P filter involved in the present invention are simple, and the transmission curve of the F-P filter can be calibrated more accurately.

(2) Simultaneously measure the laser light intensity and the transmitted light intensity of the laser through the F-P filter to calculate the transmittance, so as to avoid the influence of the light source output power change on the transmittance calculation, and the stability of the light source output power is relatively low.

Description of drawings

Fig. 1 is the flow chart of the transmission curve method of calibration F-P filter of the present invention;

Fig. 2 is the schematic diagram of the experimental device of calibration;

The meanings of the reference symbols in the figure are: 1 is the frequency-stabilized He-Ne laser, 2 is the beam expanding collimator, 3 is the beam splitter, 4 is the F-P filter to be calibrated, 5 is the first CCD, and 6 is the second CCD .

Detailed ways

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

As shown in Figure 2, the frequency-stabilized He-Ne laser 1 generates a narrow-band frequency-stabilized laser during calibration, which is divided into two channels of equal intensity by the beam splitter 3 after passing through the beam expander collimator 2, one of which is directly transmitted by the second CCD 6 The optical power is measured, and the other way passes through the F-P filter 4 to be calibrated and then enters the first CCD 5, and the computer controls the tuning of the F-P filter 4 to be calibrated and the image acquisition of the first CCD 5 and the second CCD 6. In order to avoid the impact of the CCD response difference and the beam splitting error of the beam splitter 3 on the measurement, the response of the two CCDs and the beam splitting ratio of the beam splitter 3 should be calibrated before the calibration of the F-P filter 4 to be calibrated. As shown in Figure 1, the specific process of calibrating the F-P filter 4 to be calibrated is as follows:

Step 1, using a frequency-stabilized He-Ne laser 1 with an extremely narrow bandwidth to generate a frequency-stabilized laser beam and expanding the beam and collimating the beam through a beam-expanding collimator lens 2;

Step 2, do not put the F-P filter 4 to be calibrated, calibrate the response of the first CCD 5, the second CCD 6 and the splitting ratio of the spectroscope 3;

Step 3, utilize the beam splitter 3 to divide the laser light into 2 beams, one beam directly enters the second CCD 6, and the other beam is received by the first CCD 5 after passing through the F-P filter 4 to be calibrated;

Step 4, adjust the tuning position of the FP filter 4 to be calibrated at a certain tuning wavelength λ _i , and simultaneously measure the laser output light power and the transmitted light power of the laser through the FP filter 4 to be calibrated;

Step 5, using the response characteristics of the first CCD 5, the second CCD 6 and the spectral ratio of the spectroscope 3 to correct the measured value and calculate the transmittance;

Step 6, changing λ _i , repeating steps 4 and 5, measuring multiple sets of transmittance A-tuning wavelength λ data, fitting the curve with a Gaussian function, and calculating the half-width of the curve and the peak transmittance. Let the fitted Gaussian function curve be:

then there is,

A _m = a

In the formula, A is the transmittance, a, b, λ ₀ are the fitting parameters to be calculated, Am is the peak transmittance of the _FP filter to be calibrated, and w is the half-width of the FP filter to be calibrated.

Claims (1)

1. a method for calibrating an F-P filter transmission curve utilizing a frequency-stabilized He-Ne laser, is characterized in that the steps are as follows: Step 1, using a frequency-stabilized He-Ne laser with an extremely narrow bandwidth to generate a frequency-stabilized laser and expand the beam for collimation; Step 2, do not put the F-P filter to be calibrated, calibrate the response of the first CCD, the second CCD and the beam splitter ratio; Step 3, using a beam splitter to divide the laser into two beams, one beam directly enters the second CCD, and the other beam is received by the first CCD after passing through the F-P filter to be calibrated; Step 4, adjust the tuning position of the FP filter to be calibrated at a certain tuning wavelength λ _i , and simultaneously measure the laser output light power and the transmitted light power of the laser passing through the FP filter to be calibrated; Step 5, using the response characteristics of the first CCD, the second CCD and the spectral ratio of the spectroscope to correct the measured value and calculate the transmittance; Step 6, changing λ _i , repeating steps 4 and 5, measuring multiple sets of transmittance A-tuning wavelength λ data, fitting the curve with a Gaussian function, and calculating the half-width of the curve and the peak transmittance.

Images