SU1509688A1 - Device for measuring reflection factor of mirror - Google Patents

Abstract

This invention relates to a measurement technique. The aim of the invention is to improve the measurement accuracy. The device is made according to a symmetric scheme and contains a radiation source 1, installed along the radiation of a mirror 2.5-7, beam-splitting plates 8, 9 and photodetectors 10-13,16,17, two of which (16 and 17) are position-sensitive and optically coupled to the mirror 15 under study through the surface of the corresponding beam-splitting plate external to it. In this case, the examined mirror 15 is placed between the beam-splitting plates 8 and 9 in the holder 14 mounted for rotation around mutually perpendicular axes lying in a plane perpendicular to the optical axis of the device. The invention makes it possible to significantly improve the accuracy of measuring the reflection coefficient of a mirror by ensuring that it is installed perpendicular to the probing radiation, which, reflected from the mirror under study, falls on the same area of the working surface of the measuring photodetector. 1 il.

Description

one.

(21) 4367404 / 24-25

(22) 01/25/88

(46) 09/23/89. Bul No. 35

(72) E.I. Chernov and O.L.Holovkov

(53) 535.242 (088.8)

(56) USSR author's certificate

No. 1032875, cl. G 01 N 21/55, 1983.

Fox M.P., Molinko V.N., Terekhova Sof. Reflection of single crystals of CdSySe, - in the field of its own absorption - Physics and technology of semiconductors. 1962, t3, number 4, pp. 578-582.

(54) DEVICE FOR MEASURING THE REFLECTION RATE OF THE MIRROR (57) The invention relates to a measurement technique. The aim of the invention is to increase the measurement accuracy. The device is made according to a symmetric scheme and contains a radiation source 1, installed along the radiation of the mirror 2.5 - 7, the beam-distributing plates 8.9 and photoreceptions 10 - 13,16,17, two of which (16 and 17) are are position-sensing31509

and optically connected with the mirror 15 under study through the surface of the corresponding beam-splitting plate external to it. At the same time, the examined mirror 15 is placed between the beam-distributing plates 8 and 9 in a holder 14 mounted for rotation around mutually perpendicular axes lying in a plane,

perpendicular to the optical axis of the device. The invention makes it possible to significantly improve the measurement accuracy of the reflection coefficient of a mirror by ensuring that it is installed perpendicular to the probing radiation, which, reflected from the mirror under study, falls on the same area of the working surface of the measuring photodetector, I il.

20

The invention relates to a measurement technique and can be used to measure the reflection coefficient of the mirror surfaces of optical elements.

The purpose of the invention is to show the accuracy of the reflection coefficient measurement.

The drawing shows a diagram of the device, - 25

The device contains a radiation source 1 J, a translucent mirror 2, removable plugs 3 and 4, swiveling mirrors 5-7 and two beam splitting plates 8 and 9 with photodetectors, Q

(OP) 19-13, I

Between the plates 8 and 9 is located

the mirror holder 14 on which the optical element under study is mounted is a mirror 15.35

The FP 10 and 12 are optically coupled to the outer surfaces of the plates 8 and 9 (with respect to the mirror holder 14), and the FP 11 and 13 to the inner surfaces of the plates 8 and 9.40.

The device also contains position-sensitive photodetectors (PFPs) 16 and 17, the PFP 16 is optically coupled to the outer surface of the plate 8, and the PFP 17 is connected to the outer surface of the plate j j 9,

The mirror holder 14 is rotatable about two mutually perpendicular axes lying in a plane perpendicular to the optical axis of the device.

The device works as follows.

The determination of the desired reflection coefficient of the mirror 15 is reduced to four rem. Measurements,

1, At the first measurement with a plug 4, block the luminous flux, post i fingering to the mirror 6, plug 3 kill 20

go round Mirror 15 is also removed. Part of the luminous flux Φ, incident on the plate 8, is reflected on the AF 10, and the second part of this flux passes the plate 8, is reflected from the plate 9 and falls on the OP 13, Output signals U, t, and on the OP 10 and 13, respectively, are equal

and o „-p8-o, o; ,

(I) (2)

de pg | - reflection coefficient from

the outer surface of the plates 8; g - transmittance

plates 8; . p% is the reflection coefficient of

the inner surface of the plate 9;

 sensitivity, respectively, the OP 10 and OP 13,

Result of the first measurement

X,

ulo / s

s

(3)

2, In the second dimension, a mirror 15 is mounted with a mirror surface on the plate 8. The mirror holder 14 is rotated around two mutually perpendicular axes lying in a plane perpendicular to the optical axis of the device, so that the light beam reflected from the mirror 15 and then reflected from the outer surface of the plate 8, fell into the center of the cross of the PDE 16, while the light beam reflected from the mirror 15 and from the inner surface of the plate 8 falls into a predetermined area W 11 Output signals (W 10 and II, for eton are equal

2

, 0

9

n

P8.

Od

ten

I7 e-Px-P8v ii0

Where

P. 1509688

() gives the specified area of the sensitive surface of the FP 13, (5) The output signals 12 and 13 at the same time

with equal

the value of the light incident on the place, the current flow,

tina 8 during the second measurement;

pX is the desired reflectance of the mirror 15;

Pb4 is the reflection coefficient of the inner surface of the plate 8;

oi, | - sensitivity OP 1, 15 The result of the second measurement

,

.3

9"

(R.

g-1

9.

P ") 1

.ti

g

22

R.-P

);

(ten)

(M)

where t is the current increase in the luminous flux incident on the plate 9 from the side of the mirror 7 during the fourth measurement. Fourth measurement result

X.

3, Before the third measurement, install the plug 3 and remove the plug 4. Mirror 15 is also removed. Part of the luminous flux (p, falling on the plate 9 is reflected from its outer surface and goes to the photo-ferro 12, and the second part of the light flux passes the plate 9, reflects from the inner surface of the plate 8 and enters the W 11, the output signals of the OP 12 and 11 are equal

and 12), - 1g,

it

 Pea

where PQJ is the reflection coefficient from the external surface of the plate 9;

0 (2 is the sensitivity of the OP 12; s is the transmittance

plates 9, the result of the third dimension

X, u j / U,%

(9)

4, Before the fourth dimension, install the studied mirror 15 with a mirror surface to the plate 9. The mirror holder is rotated around two mutually perpendicular axes lying in a plane perpendicular to the optical axis of the device, so that the light beam reflected from the mirror 15 and then from the outside the surface of the plate 9, fell into the center of the cross 17. In this case, the light beam reflected from the mirror 15 and from the inner surface of the plate 9, butt.

.3

9"

(R.

g-1

9.

P ") 1

.ti

g

22

R.-P

);

(ten)

(M)

de t is the current decrease of the luminous flux incident on the plate 9 from the side of the mirror 7 during the fourth measurement. Fourth measurement result

(6)

and "/ and

s

(12)

Solving the system from expressions (1) - (5), (7), (8), (10) and (II) with respect to the RC and passing to the values Xf, X2, X and X4u, we obtain the desired reflection coefficient

25

p, l | x, - X2 / Xj.X4. (13)

thirty

40

The result obtained for the reflection coefficient of the mirror 15 does not depend on the magnitude of the luminous flux or on the characteristics of the optical elements.

In addition, the introduction of two position-sensitive photodetectors 16 and 17 into the circuit of the device makes it possible to eliminate errors due to the uneven sensitivity of the working sites of the OP 10–13,

Thus, the invention makes it possible to improve the measurement accuracy of the reflection coefficient of the mirror 15 without significantly complicating the device.

Claims (1)

Apparatus of the Invention A device for measuring the reflection coefficient of a mirror, comprising a radiation source, a translucent mirror arranged along the radiation path, rotating mirrors, two light-transmitting plates, a mirror holder and four photoreceptions, two of which are optically connected to surfaces splitting plates, and the other two with their internal surfaces, characterized in that, in order to improve the measurement accuracy, the device additionally 71509688 8 contains two poetic-sensing-fuller with the possibility of rotation of the relative photodetector, each of which in two mutually perpediculars is p-optically connected with the outer surface axes lying in the plane, with the perpendicular optical beam axis of the device plate, and the holder is a high-quality mirror.