Method of correcting shape of surface of optical components

FIELD: physics.

SUBSTANCE: method involves local laser deposition of a layer of transparent or opaque material on the surface. Laser deposition is carried out on mirror reflecting adjacent surfaces or coatings of plates already mounted in an interferometer in the gap between surfaces. The gap is filled with a medium which forms a film upon laser irradiation, and the surface is locally irradiated with laser radiation. Thickness of the deposited layer of material can be controlled during deposition by interference measurement of deviation of the length of the optical path of the light beam between the mirror reflecting surfaces of the interferometer plates from the resonance length for the interferometer. The laser beam can scan the surface, wherein its intensity can be modulated with the length of the optical path between the mirror reflecting surfaces.

EFFECT: correcting the shape of surfaces of optical components already mounted in an optical device.

3 cl, 1 dwg

 

The invention relates to optical technologies, laser methods of obtaining thin films on the surface of bodies, in particular, to methods for aligning the surfaces of optical parts by local application to the surface of the thin compensating non-uniformity of the layers.

Examines issues of technology of repair of optical non-uniformity of air gaps in the multibeam interferometers, the position of the mirrors are in the manufacture of the devices are fixed and cannot ostrovacice. Distortion can make the gap, for example, the shape of a wedge or be caused by the flatness of the substrate mirror coatings interferometers.

Real surfaces have varying degrees of flatness. For example, in serial optical manufacturing when manufacturing products of the highest accuracy class the tolerance for deviation of the surface shape of the mirrors of precision instruments is determined by the number of rings of interference N=0.1 to 0.5 (0.05 to 0.25 μm in diameter on the order of 10 cm).

The task of obtaining the air gap becomes much more complicated when you need to stand flat on the entire surface of the wafer hundredths and less share of the wavelength of light required in optical devices because it is difficult manufacture of the plates with the specified flatness./p>

In particular, there is an actual need for improved optical non-uniformity ("dressed") air gaps in the already made interferometers or other optical devices with the same "interferometric" requirements for uniform air gaps. Often the necessary "adjustments" quality of the interferometer to the level of λ/100 and less optical uneven air gap between the mirrors of the interferometer.

Analogue of the invention is a method of vacuum aspherical, namely, that on the polished surface of the optical parts, if necessary, adjusting its form is applied by sputtering in a vacuum substance layer of variable thickness. The necessary change of the layer thickness in the zones aspherical surface is provided with a mask-screen TV with shaped hole, installed on a flow path of steam applied substances. Changing the thickness of the zones is achieved by the fact that the opening of the separate zones for the passage of deposited substances varies and depends on the shape of the cutouts in the mask [Kashirin Century. And. principles of formation of the optical surfaces. GOU VPO "Ural state technical University - UPI, Ekaterinburg, 2006]. The disadvantage of this method is its application in the production stage details the impossibility of adjusting items after E. the Assembly and fastening of the optical device, using this item.

The prototype of this method is the method of laser deposition of layers of a pair of decomposing under the action of radiation chemical compounds (LCVD method) (Chesnokov V.V., Reznikov E.F., Chesnokov A.I nanosecond Laser microtechnology / Under the General editorship A.I Chesnokov, Novosibirsk: SSGA, 2003). In this method the surface to be coated substance, immersed in the atmosphere of steam decomposing volatile pyrolytic or photolytic chemical compounds emitting substance covering the surface and locally illuminated by a laser beam incident on the surface side, which increases the film substance. The advantage of this method is the flexibility in the management of education and the adjustment layer on the surface and the ability to conduct the deposition in atmospheric conditions. The disadvantage of this method is the impossibility of its application to fill the irregularities of the parts after Assembly and fastening in the optical device using this item.

The problem solved by the invention is a method of adjusting the shape of the surfaces of optical components that are already bonded to each other in the optical device.

The solution is achieved by a method for correcting the surface shape of the optical parts, including a local application on the surface the th layer of material, in accordance with the invention, the adjusting surface in the gap between adjacent already bonded parts, and fill in the gap environment, creating a laser irradiation on the surface of the film, and then locally irradiated with laser radiation to the surface to its inner side.

It is also proposed that the applied material over the existing mirror cover details.

It is also proposed that the cause of a transparent material.

It is also proposed that the thickness of the layer of material is controlled by the length of the optical path of the light beam between the mirror

surfaces.

It is also proposed that during the adjustment of the shape of the laser beam scans the surface, and its intensity modulated by the optical path length of light between the mirror surfaces.

The invention is illustrated by means of figure 1, which in the example illustrated, the adjustment surface of one of the mirrors of a multi-beam interferometer with a flat air gap between the mirror surfaces of the two transparent glass substrates. The application of a transparent layer on one mirrored side of the gap leads to an increase in the length of the optical path between the mirrors on the value of Δ=h(n-1), where h is the thickness of the applied layer, n is the index of refraction. For example, if necessary, to compensate for the optical is Yu heterogeneity of the size of Δ=λ/10 in the visible range of the spectrum when n=1.5, the thickness of the resulting layer should be - 100 nm. If applied opaque mirror layer, the optical path length is reduced by the thickness of the applied layer, i.e., λ/10 (~50 nm).

Refer to figure 1 where 1 and 2 are semi-transparent mirror multibeam interferometer, 3 - the case of the interferometer, 4 and 5 of the transparent substrate mirrors, 6 air gap between the mirrors, 7 - besieged island transparencies, 8 - translucent mirror, 9 - stream of monochromatic radiation backlight control optical length of the rays in the gap between the mirrors, 10 - lens focusing of a laser beam, initiating deposition of the film, 11 - scanning mirror 12 is a laser emitter, 13 - PV analyzer interference pattern 14 and 15 to the inlet and outlet vapor volatile reagent, which creates the environment in the gap between the mirrors.

During the adjustment surface of the lower mirror of the interferometer, the gap is filled through holes 14 and 15 of gaseous or liquid active transparent environment, creating a laser irradiation on the surface of the film, and then locally irradiate the mirror of a laser radiation emitter 12, the radiation is focused by the lens 10 on the inner surface of the lower semi-transparent mirror 2, when this radiation passes through the transparent substrate 4. Under the action of radiation mirrored coating 2 is heated by the thickness of totemperature pyrolysis chemical compounds included in the medium that fills the gap between the mirrors, when the pyrolysis depending on the selected chemical compounds can on the coating surface 2 to form a transparent film or an opaque reflecting metal film, forming in the illuminated region of the island 7 that its thickness changes the optical path length of light rays stream 9 in the interferometer. Control over the thickness of the resulting film in real time is carried out in the interference pattern formed in the area corresponding analyzer 13 when coverage "repaired" interferometer with an inclined semi-transparent mirror 11, is placed in the laser beam, collimated monochromatic radiation 9. Radiation 9 passes both mirrors of the interferometer and reaches the photoelectric analyzer multibeam interference pattern 13 that generates the signals for controlling the intensity of the radiation emitter 12. The intensity of the radiation, locally passing through the interferometer, the maximum at the moment of resonance, when matching the optical path lengths of light between the mirrors at the site of the interferometer with an integral number of half-waves of light.

If education is opaque to radiation 9 film interference must control the optical path length change to the scheme, working n the reflection.

In the process of adjusting the mirrors of the interferometer laser radiation with a scanning mirror 11 scans the surface of the mirror layer 2, which allows you to treat the entire surface of the mirror. The uniformity of the optical thickness of the resulting gap between the mirrors in the limit to determine the ultimate sensitivity of the circuit measuring variations of optical path length from resonance-based analyzer 13; for multibeam interferometers, assessment, achievable flatness of less than 1 nm.

After adjustments, the interferometer is released from the active medium and sealed

As the material of the transparencies can be applied transparent oxides of aluminum or silicon, which are obtained by the pyrolysis vapors of volatile compounds. To obtain films of Al2O3is used

for example, the pyrolysis vapors of aluminum isopropylate, which has sufficient volatility at 130°C, decomposes at 270-400°C with the formation of a transparent film of Al2O3. The temperature of pyrolysis must be below the temperature of the damage to the mirror coatings, which are often aluminum. For LCVD used a pulsed KRF excimer laser, nitrogen laser, continuous and pulsed radiation solid-state Nd:YAG laser with frequency doubling, etc. the Duration τ of the pulse emission of the Sabbath.

l=at,(0.1)

where a is thermal diffusivity of the layer determines the depth of the warm layer and limits the maximum film thickness length l of the heat wave in the mirror layer and the applied film. Caused by exposure from the back side of the substrate dielectric film can have a thickness of not more than a few tenths of a micron.

This method of adjustment of the mirror surfaces of the interferometers can greatly simplify and reduce the cost of their production, to improve the quality of interference devices, as it will allow you to "increase" the quality of products manufactured by the production technology, to the level of "exclusive", is much more expensive.

The method can be applied to adjust the surfaces not only flat parts that can be used when adjusting the non-spherical surfaces of optical lenses, for example, if the repair.

1. The method of adjusting the shape of the optical surfaces of the plates of the interferometer, including the local application of laser deposition on the surface of the layer of transparent or opaque material, characterized in that the laser deposition is performed on mirror adjacent surfaces or coatings already bonded in the interferometer plates in the gap between the surfaces, and fill the gap environment, creating a laser irradiation on the surface of the film, and then locally irradiated with laser radiation to the surface.

2. The method according to claim 1, characterized in that the thickness of the layer of material is controlled during the deposition of the interference measurement deviation of the length of the optical path of the light beam between the mirror surfaces of the plates of the interferometer from resonance for the interferometer.

3. The method according to claim 1, characterized in that the laser beam scans the surface, and its intensity modulated by the optical path length of light between specularly reflecting surfaces.



 

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