Measurement device and method for three-dimensional photo-thermal absorption of optical material

Abstract

The invention discloses a measurement device and a measurement method for three-dimensional photo-thermal absorption of an optical material. The device is of a transverse type structure; the material is subjected to three-dimensional photo-thermal absorption measurement by using a thermal lens technology, so that an error caused by the fact that a light spot irradiates the edge of a detector or the outside of the detector during measurement with a photo-thermal deflection technology is avoided, and a favorable tool is supplied to the research on the characteristics of the material and damage to the material; according to the method, by means of the photo-thermal deflection technology, a resistance heating calibrator is indirectly used for calibrating thermal lens absorption measurement, so that an error caused by a difference between materials during calibration of different types of samples in the thermal lens absorption measurement is avoided; meanwhile, when a parameter product between a system and the material is calculated, a thermal lens signal point to be measured and a known absorption rate point are the same point, so that the error is reduced. The device is simple, convenient to adjust and high in sensitivity.

Description

technical field [0001] The invention relates to a measuring device and method for three-dimensional photothermal absorption of optical materials. technical background [0002] Photothermal deflection and thermal lens technology has been extensively studied as an excellent means of high-sensitivity, non-destructive measurement of low absorption. When a modulated Gaussian beam is incident on the optical material, the material absorbs the energy and converts part or all of it into heat energy. Due to the uneven heat distribution, a temperature gradient will be formed inside the material. And because the refractive index of the material is a function of temperature, a refractive index gradient will be produced. If another beam of low power (the probe beam) is passed through a region of the material with a refractive index gradient, the probe beam will be deflected or defocused. By measuring the beam deflection (photothermal deflection technology) or defocusing degree (thermal ...

AI Technical Summary

Problems solved by technology

For example, the photothermal common path interferometer (PCI) of SPTS company in the United States is based on the improved thermal lens technology. The company's weak absorption measuring instrument (LID), which is based on the principle of laser-induced deflection and uses resistance heating to calibrate, is currently unable to perform three-dimensional detection, and the measurement is time-consuming

PCI, like other thermal lens devices, ignores the difference between the calibration sample and the reference sample material when measuring the photothermal absorption of the material, introducing errors

Although LID uses the same sample for calibration, when measuring areas with large absorption, such as defects, the deflected beam may hit the edge of the detector or even the outside of the detector, which makes the measurement of three-dimensional photothermal absorption of materials introduce error

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