SU1216751A2 - Method of determining bandwidth and maximum transmission wavelength of interference light filter - Google Patents

Abstract

The invention makes it possible to increase the accuracy of measuring the characteristics of an interference filter by increasing the accuracy of determining the angle of incidence of the radiation on the filter corresponding to half the maximum of the intensity of the transmitted radiation. For this, simultaneously with recording the intensity of the radiation transmitted through the filter, the angle of incidence of the beam on the filter is measured, corresponding to the maximum of the intensity of the transmitted radiation. The angle of incidence of the radiation on the filter corresponding to half the maximum transmission is measured at the moment when the difference between the intensities of the transmitted and reflected radiation is equal to the intensity of the radiation reflected from the optical filter at the angle of incidence corresponding to the maximum transmission of the optical filter. The constant component of the reflected beam can be measured by installing the filter at an angle corresponding to its maximum transmittance. Q S (L ate

Description

The invention relates to optical-KObfy instrument making, in particular to methods for measuring the characteristics of high-pass interference filters, and is an improvement of the known method according to the author. St. No. 1024862.

The aim of the invention is to increase the measurement accuracy of the characteristics of an interference light filter by increasing the accuracy of determining the angle of incidence of radiation on the light. a filter corresponding to half the maximum of the intensity of the last radiation.

According to the main author. St. No. 1024862 discloses a method for determining the bandwidth and a wave of a maximum transmission wavelength of an interference optical filter by scanning it with a parallel beam of monochromatic light and then recording the transmitted radiation intensity when the angle of incidence of the radiation changes to the optical filter. Transmission is carried out by radiation with a wavelength. shorter length, corresponding to the maximum pass of the filter. Next, the angle of incidence of the beam on the filter corresponding to the maximum of the transmitted radiation intensity is measured, as well as the angle of incidence corresponding to the half of the maximum of the intensity of the transmitted radiation. The width of the band and the wavelength of the maximum transmittance are determined by the following relations:

four,)

Ul fQjMK l Q:

 maize

de is the wavelength corresponding to the maximum transmittance:

Aj, is the wavelength of the transmission beam:

 max is the angle of incidence of the beam on the filter corresponding to the maximum intensity of the transmitted radiation;

P is the refractive index of the separation layer of the filter;

51 .2

S-ii - the bandwidth of the pass-no filter; Qg, is the angle of incidence of the beam on the filter corresponding to half the maximum of the intensity of the transmitted radiation. It is known that the shapes of the transmission band and the reflection of the narrowband interference filter are mutually additional, therefore, provided that the loss of light energy to absorption inside the filter is small, the intensity of the reflected radiation and the radiation transmitted through the filter are also complementary to each other with an accuracy of . Thus, by eliminating the constant component of the reflected beam, it is possible to obtain

that at the angle of incidence of the light radiation corresponding to half

the maximum transmission of the filter, the intensity of the reflected and transmitted

through the light filter

are the same, and their difference is zero. This situation allows us to more accurately determine the angle corresponding to half the maximum transmission

light filter. Therefore, the constant component of the reflected beam: can be measured by installing the filter at an angle corresponding to its maximum transmittance.

In the process of measuring the angle of inclination of the light filter, two similarly high fluxes are measured, so the measurement error caused by the non-linearity of the photoreceiver is small. In addition, the effect of interfering background light is significantly weakened, as the error introduced by them is proportional to the difference in the light fluxes of the background radiation, and the n – g light flux itself. For good reason, the instability of the power of the radiation source also has little effect on the measurement results.

The proposed method makes it possible to increase the accuracy of measuring the main characteristics of narrowband and contrast light filters of various orders.

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Claims (1)

Invention Formula The method of determining the bandwidth and wavelength of the maximum transmission of an interference filter according to the author. St. No. 102D862, which is based on the fact that, with the aim of increasing the accuracy of measurement of the characteristics of the interference filter by increasing the accuracy of determining the angle of incidence of radiation on the filter corresponding to half of the maximum intensity of the transmitted radiation, 167Ы-4 through the filter of radiation of re-. The intensity of the radiation reflected from it is reflected, and the angle of incidence of radiation on the optical filter, corresponding to half of the maximum transmission, is measured at the moment when the difference between the intensities of transmitted and reflected radiation is equal to the intensity of the reflected optical radiation filter at 10 times the angle of incidence light filter.