JPS5912129B2 - Laser light absorption measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an absorption rate measuring device that can measure the absorption rate of a laser beam reflective material having a low absorption rate with high accuracy.

Conventional absorption rate measuring device (APPLIED OPTICS, June 1974, VOL 13, Mu 6,
APPARATUS FORTHEMEA SUREMEN
TOFOPTICAL ABSORPTIVITYINL
As shown in FIG. 1, the ASERMIRRORS includes a laser oscillator 1 that irradiates light onto a reflective material 8, a vacuum chamber 2 that includes a built-in calorimeter, and an exhaust pump 3 that evacuates the inside of the vacuum chamber 2. A transmission window 4 that allows the laser light to pass through, a light shielding plate 5 that prevents the scattered light generated when the laser light passes through the transmission window 4 from directly hitting the sample holder 10, and an absorbing reflective material 8. A first calorimeter 6 for measuring energy and a reflective material 8
and a second calorimeter T for measuring reflected energy from.

15 In order to eliminate measurement errors due to heat convection, the inside of the vacuum chamber 2 is evacuated by the exhaust pump 3, and the laser beam from the laser oscillator 1 is made incident on the reflective material 8 through the transmission window 4.

Absorber 18 absorbs all the laser light reflected by reflective material 8
absorb with. (2) A light shielding plate 5 having a hole with a diameter smaller than the effective diameter of the reflective material 8 is placed as close as possible to the reflective material 8 to prevent the laser beam from directly hitting the sample holder 9.
The energy absorbed by the reflective material 8 is detected by the first force 25 and the energy absorbed by the absorber 18 is detected by the second calorimeter T, and the sum of the detection energy of both is detected by the reflective material 8. The energy of the laser beam incident on the first calorimeter 6 and the energy of the incident laser beam? 0 Reflective material 8 from the energy ratio
Obtain the absorption rate of

The first calorimeter 6 and the second calorimeter 7, for example, as shown in FIG. It is composed of a power source 14 for supplying energy to the electric heater 10, a radiation shield 15, a constant temperature body 16, and a constant temperature cooling device 1T. At the time of laser beam irradiation, the energy absorbed by the reflective material 8 and the absorber 18 is absorbed by the constant temperature body 16 via the thermomodule 11 for temperature detection.

A minute voltage corresponding to a temperature difference occurring in a thermomodule 11 for temperature detection is amplified by an amplifier 12 and displayed on a recorder 13 to obtain an output voltage in a thermal equilibrium state. Next, the energy supply power source 14 generates Joule heat in the calibration electric heater 10 to calibrate the energy absorbed during laser beam irradiation.

By keeping the radiation shield 15 and the constant temperature body 16 at a constant temperature during the measurement using the constant temperature cooler 17, it is possible to reduce the amount of energy received from surrounding objects when measuring the absorbed energy by laser beam irradiation and when calibrating the absorbed energy by the calibration electric heater 10. This is to prevent calibration errors due to differences in radiant heat and differences in sensitivity of the temperature detection thermomodule 11 due to temperature changes in the constant temperature body 16, and errors in reading the outgassing pressure in a thermal equilibrium state. The light shielding plate 5 is attached to the radiation shield 15 or the constant temperature body 16 in order to reduce as much as possible the temperature rise caused by the scattering light.

However, it is very difficult to keep the light shielding plate 5 at exactly the same temperature when the scattered light hits it and when it does not hit it, and a slight temperature difference occurs. In addition, the heat conducted from the light shielding plate 5 to the constant temperature body 16 causes a temperature distribution in the constant temperature body 16, and the temperature of the contact part of the first calorimeter 6 with the thermomodule 11 for temperature detection is changed by the electric current for calibration. There is a slight difference in temperature from the temperature at the time of energy calibration by the heater 10. When measuring the absorption rate of a reflective material with low absorption rate, since the energy absorbed by the reflective material is minute, the light shielding plate 5
The difference in radiant energy due to a small temperature difference from
Detects high output voltage and therefore exhibits high absorption rate. Further, a slight temperature change in the constant temperature body 16 causes a calibration error. As explained above, the conventional apparatus has the disadvantage that it is not possible to accurately measure the absorbance of a reflective material having a low absorbance.

An object of the present invention is to eliminate the absorption energy detection error of the reflective material caused by the radiant energy from the light shielding plate and the absorption energy calibration error of the reflective material caused by the conductive heat from the light shielding plate. An object of the present invention is to provide an absorption rate measurement device that can measure the absorption rate of a reflective material having a low index with high precision.

In order to achieve the above object, the absorption rate measuring device of the present invention receives radiant heat and conductive heat equally from the light shielding plate as the first calorimeter 6 on the same constant temperature body, and also has the cooling effect of the constant temperature cooler. It has a structure in which a third calorimeter 19 having exactly the same performance as the first calorimeter 6 is added at the same position as the first calorimeter 6.

FIG. 3 shows an embodiment of the present invention, in which 19 is a third calorimeter.

The third calorimeter 19 shares a constant temperature body and a constant temperature cooler with the constant temperature body 16 and constant temperature cooler 17 of the first calorimeter 6, and also calibrates the reflective material 8 and sample holder 9 of the first calorimeter 6. The electric heater 10 and the thermomodule 11 for temperature detection are each made of the same thing, and the distance from the center of the third calorimeter 19 to the light shielding plate 5 and the constant temperature cooler 17 on the constant temperature body 16 is The calorimeter 6 is installed at a position equal to the distance from the center of the calorimeter 6.

In the measurement of absorbed energy by laser light, the third calorimeter 19 detects the detection error ΔV1 of the first calorimeter 6 due to the radiant energy from the light shielding plate 5 and the temperature change of the constant temperature body 16 due to the conductive heat from the light shielding plate 5. The detection error ΔV2 exerted on the first calorimeter 6 is detected at the same time.

Output voltage V of the temperature detection thermomodule of the first calorimeter 6.

+(ΔV1+ΔV2) minus the output voltage ΔV1+Δ2 of the temperature detection thermo module of the third calorimeter 19. is amplified by the amplifier 12 and displayed on the recorder 13. The output obtained by the absorption rate measuring device according to the present invention is obtained by removing errors caused by radiant energy from the light shielding plate 5 detected by the conventional device and errors caused by conductive heat from the light shielding plate 5, Therefore, electric heater 1 for calibration
The absorption energy of the reflective material 8 calibrated by 0 is obtained by removing the influence of scattered light that occurs when the laser light passes through the transmission window 4. In the absorption measurement device according to the present invention, a plano-convex lens is used for the transmission window 4 in order to minimize the amount of scattered light, and a plano-convex lens is used in the transmission window 4 to minimize the temperature rise of the light shielding plate 5. Of course, it improves thermal contact.

As explained above, the absorption rate measuring device according to the present invention has the following features:
The absorbance of reflective materials with low absorbance can be measured with high precision.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional absorption rate measuring device, FIG. 2 is an explanatory diagram of a calorimeter, and FIG. 3 is an explanatory diagram of an embodiment of the present invention. Regarding the symbols used in the drawings, 1 is a laser oscillator, 2 is a vacuum chamber, 3 is an exhaust pump, and 4 is a vacuum chamber.
is a transmission window, 5 is a light shielding plate, 6 is a first calorimeter, 7 is a second calorimeter, 8 is a reflective material, 9 is a sample holder, 10 is an electric heater for calibration, 11 is a thermomodule for temperature detection, 12 is an amplifier, 13 is a recorder, 14 is an energy supply power supply, 15 is a radiation shield, 1
6 is a constant temperature body, 17 is a constant temperature cooler, 18 is an absorber, and 19 is a third calorimeter.

Claims (1)

[Claims] 1. A vacuum chamber equipped with a laser beam and a laser beam transmission window, a first calorimeter arranged in the vacuum chamber for measuring the absorbed energy of a material that reflects the laser beam, and a first calorimeter arranged in the vacuum chamber for measuring the absorbed energy of a material that reflects the laser beam. In an apparatus for measuring the absorption rate of a laser beam reflective material, which is equipped with a second calorimeter that measures reflected energy from the material, scattered light generated when the laser beam passes through a transmission window is directly applied to the holder of the reflective material. A third calorimeter having exactly the same performance as the first calorimeter is added at a position that receives radiant heat and conductive heat equal to the first calorimeter from a light shielding plate provided to prevent the heat from being projected. A laser light absorption rate measuring device.