RU2658572C1 - Laser lighting - Google Patents

Abstract

FIELD: lighting equipment.

SUBSTANCE: invention relates to light modulation by methods of controlling the intensity and phase characteristics of the light flux, and can find application for laser light sources of general purpose, including for the destruction of spatial and temporal coherence, suppression of speckle. Laser illuminator comprises consecutively arranged on the optical axis at least one coherent light source, lens, modulator, Fourier lens, phase filter, output lens. Phase filter is placed in the focus of the Fourier lens and overlaps the light flux of the laser radiation in zero order. Modulator comprises a first dielectric transparent substrate with a transparent electrically conductive layer covered with a transparent gel-like layer on one side, and a second dielectric transparent substrate with an array of transparent electrodes on one side. Substrates are arranged in such a way that a gap is formed between the gel-like layer and the electrodes.

EFFECT: technical result is the reduction of noise of the formed distribution of radiation by spatial suppression of speckles, and also the expansion of the scope of application of the laser illuminator.

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Description

Technical field

The invention relates to light modulation by methods of controlling the intensity and phase characteristics of the light flux, and can be used for general-purpose laser light sources, including for destroying spatial and temporal coherence, suppressing speckle, and in a number of other special applications, in the optical-mechanical industry, television, printing, communications, fiber-optic switching and filtering devices, high-speed line and dot-matrix printers and other fields of technology.

State of the art

Known laser illuminator containing a rotating diffuser, a step motor with oscillatory motion and a control device [Akio Furukawa, NorihiroOhse, Yoshifumi Sato, Daisuke Imanishi, Kazuya Wakabayashi, Satoshi Ito, KoshiTamamura and Shoji Hirata, "Effective speckle reduction in laser projection displays" . of SPIE Vol. 6911, 69110T, (2008)].

The disadvantage of this device is the use of moving parts, large dimensions and light loss when suppressing speckle.

Also known is a laser illuminator comprising a rotating optical fiber tow, an engine for rotating the optical fiber tow, and a control device. The disadvantage of this device is the low level of speckle suppression, large losses in the luminous flux of laser radiation. [Mingjie Sun, Zukang Lu, "Speckle suppression with a rotating light pipe", Optical Engineering 49 (2), 024202, 2010]. A known laser illuminator comprising a phase plate representing a phase diffraction optical element on which various sequences of noise codes are applied, for example, a Barker code, wherein each optical element shifts the phase incursion of the light by ± π. [Victor Yurlov, Anatoly Lapchuk, Sangkyeong Yun, Jonghyeong Song and Haengseok Yang, "Speckle suppression in scanning laser display", Appl. Opt. Vol. 47, No. 2, (2008)]. The main disadvantage of this device is the low suppression of speckle contrast and the inability to use the movement of the phase diffraction pattern imprinted in the phase plate.

The closest invention is a laser illuminator comprising a modulator and a control device, the modulator comprising a transparent electrically conductive layer coated with a transparent gel layer deposited on a first transparent substrate, and a system of i pieces of parallel tape grounding and control electrodes. (Patent No. 2577802, Speckle suppressor for laser radiation (options), IPC classes ⁷ : G02F 1/00). A disadvantage of the known device is the linear structure of the electrodes and the inability to continuously suppress speckle.

The technical problem and the technical result

The objective of the present invention is to reduce the noise generated radiation distribution by spatial suppression of speckles. The technical result is also the expansion of the scope of the laser illuminator.

Decision

The problem is solved using a laser illuminator, which contains at least one coherent light source, a lighting lens, a modulator, a Fourier lens, a phase filter, an output lens, sequentially located on the optical axis, while the phase filter is placed in the focus of the Fourier lens and overlaps the luminous flux of laser radiation in the zero order, and the modulator contains a first dielectric transparent substrate with a transparent electrically conductive layer coated with a transparent gel-like layer on hydrochloric side, and a second transparent dielectric substrate with an array of transparent electrodes on one side, and the substrate are arranged in such a way that between the gel layer and the electrodes form a gap. Moreover, each electrode is electrically connected to a control device, which contains a clock generator that sets the sequence of voltage pulses on each electrode with the possibility of shifting the voltage across the electrodes by one or more clock cycles. An even number of electrodes is selected for more than two, and the topology of the electrodes covers the light aperture of the second dielectric transparent substrate, while all the electrodes are electrically isolated from each other, and the sequence of voltage pulses from the outputs of the control device to the inputs of the transparent electrodes is supplied according to a given law depending on the number of transparent electrodes . The phase filter is made in the form of a mirror, and a prism of total internal reflection is introduced on the optical axis, which is optically in contact with the first transparent dielectric substrate.

To implement the device, a method is proposed for suppressing speckle in laser illuminators, characterized in that the light from the coherent source is sequentially directed to the lens, modulator, Fourier lens, phase filter located in the focus area of the Fourier lens, an output lens, and to the modulator, containing the first dielectric transparent substrate with a transparent electrically conductive layer coated with a transparent gel-like layer on one side, the second dielectric transparent substrate with an array of light coatings an aperture of transparent electrodes on one side, voltage pulses are supplied to mismatch the phase of the light flux.

Description of drawings

In FIG. 1 shows a general diagram of a laser illuminator.

In FIG. 2 shows the design of the modulator.

In FIG. 3 shows a diagram of a control device with n electrical outputs.

In FIG. 4 shows two examples (A) and (B) of the topology of a system of n transparent (opaque) electrodes of various configurations.

In FIG. 5 shows an example of a system of electrical voltages at the input electrodes of the 1st, 2nd, 3rd, 4th ... nth to create a continuous traveling wave on the free surface of the gel-like layer; (a), (c) and (c) are examples of phase shift by one clock cycle.

In FIG. 6 shows a general diagram of a laser illuminator with a prism of total internal reflection introduced into the optical channel.

Detailed Solution Description

The laser illuminator (Fig. 1, 2, 3, 4, 5) contains at least one coherent light source 1, a lighting lens 2, a modulator 3, a Fourier lens 4, a phase filter 5, an output lens 6, sequentially located on the optical axis wherein the phase filter 5 is placed in the focus of the Fourier lens 4, and the size of the phase filter 5 is selected so that the phase filter 5 blocks the light flux of the laser radiation in zero order, and the modulator 3 contains a transparent electrically conductive layer deposited on the first dielectric transparent substrate 7 8, covered with a transparent gel-like layer 9, and a system of n pieces of transparent electrodes 11 of a given topology, located on the second dielectric transparent substrate 12 in the same plane and placed with a gap 10 above the transparent gel-like layer 9, and electrically connected to the control device 15, while n the outputs of the control device 15 are connected to n inputs of the system of transparent electrodes 11, while the control device 15 contains a clock generator defining a sequence of voltage pulses 16 at each electrode 11 with the voltage shift across the electrodes 11 by one or more cycles, where n is an even number of at least 4 (to create a traveling wave), while the arbitrary shape of the topology of the system of n transparent electrodes 11 covers the light aperture 14 of the second dielectric transparent substrate 12, and all n transparent electrodes 11 are electrically isolated from each other, a sequence of voltage pulses 16 from n outputs of the control device 15 to n inputs of transparent electrodes 11 are supplied according to a given law depending on the number of transparent electrodes 11 s.

As an example implementation of the invention, the device may include a phase filter 5, made in the form of a mirror.

As an example implementation of the invention, the device may contain on the optical axis a prism of total internal reflection 17, optically in contact with the first transparent dielectric substrate 7.

Coherent light source 1 (Fig. 1) using a lighting lens 2 forms aperture of the modulator 3 (Fig. 2) coherent light radiation.

The control device 15 (Fig. 3) generates electrical pulses (Fig. 5), which is a sequence of voltage pulses 16 that come to the input of the transparent electrode system 11 (Fig. 4). The sequence of voltage pulses 16 forms a relief with a height from 0 to a maximum corresponding to the optical phase incursion for a given wavelength equal to π on a transparent gel-like layer 9. The control device 15 shifts the sequence of voltage pulses 16 by one clock. A traveling wave is created on the surface of the transparent gel-like layer 9 wave.

The traveling wave is a tunable diffraction grating, which creates a diffraction spectrum in a plane perpendicular to the optical axis at the location of the phase filter 5.

The quality of speckle suppression is determined by the speed of the traveling wave and its amplitude. Diffracted light entering the first and higher diffraction orders does not fall on the phase filter 5. Undiffracted light (zero order) is blocked by the phase filter 5 and does not reach the output lens 6. Thus, the luminous flux after the output lens 6 is a scalar flux, which cannot cause speckle on any rough surface.

Since the topology of the transparent electrode system 11 is a spatial structure (Fig. 4A and Fig. 4B), the light in the plane of the phase filter 5 diffracts in all directions, unlike the prototype.

In another embodiment of the invention (Fig. 1), the device operates as follows.

Zero-order light radiation, incident on the phase filter 5, creates optical noise. The use of a phase filter 5, made in the form of a mirror, allows to eliminate optical noise by directing zero-order light radiation, for example, to a light trap.

In another embodiment, the invention operates as follows (Figs. 1 and 6).

The total internal reflection prism 17 is introduced on the optical axis, which is optically in contact with the first transparent dielectric substrate 7. The total internal reflection prism 17 eliminates optical noise in the laser illuminator due to the fact that the light flux does not pass through the system of transparent electrodes 11, reaching the Fourier lens four.

An example implementation of the invention

The device of the present invention can be performed as follows.

As a coherent light source 1, for example, semiconductor lasers or lasers based on copper, gold, strontium, and also gas lasers can be used. As elements of the control device 15 can be used standard chips or chipsets, the level of integration depends on the technical requirements of the devices.

The system of transparent electrodes 11 can be made of indium oxide, aluminum, chromium, molybdenum. As other elements and blocks, standard elements and blocks can be used. The gap 10 can be selected, for example, 10 μm, and the thickness of the transparent gel-like layer 9, for example, 45 μm. The thickness of the transparent electrodes 11 can be selected from tenths to hundredths of a micron. The electrical signals coming from the control device 15 to the input of the modulator 3 can, for example, be selected as follows: the maximum signal voltage is 15-20 Volts, the clock frequency, for example, 50 kHz.

A transparent gel-like layer 9 is prepared on the basis of polyorganosiloxane by known methods (Patent No. 2577802, Speckle suppressor for laser radiation (options), IPC classes ⁷ : G02F 1/00).

The first dielectric transparent substrate 7, the second dielectric transparent substrate 12, the total internal reflection prism 17 must be made of one material, for example, silica glass. The transparent conductive layer 8 is made of indium oxide.

Claims (7)

1. A laser illuminator comprising at least one coherent light source sequentially located on the optical axis, a lighting lens, a modulator, a Fourier lens, a phase filter, an output lens, the phase filter being placed in the focus of the Fourier lens and blocking the light flux of the laser radiation in zero order, the modulator comprising a first dielectric transparent substrate with a transparent electrically conductive layer coated with a transparent gel-like layer on one side, and a second dielectric translucent a substrate with an array of transparent electrodes on one side, the substrates being arranged so that a gap is formed between the gel layer and the electrodes. 2. The device according to p. 1, characterized in that each electrode is electrically connected to a control device that contains a clock generator that sets the sequence of voltage pulses on each electrode with the possibility of shifting the voltage across the electrodes by one or more clock cycles. 3. The device according to p. 2, characterized in that it contains an even number of electrodes of more than two. 4. The device according to claim 3, characterized in that the topology of the electrodes covers the light aperture of the second dielectric transparent substrate, while all the electrodes are electrically isolated from each other, and the sequence of voltage pulses from the outputs of the control device to the inputs of the transparent electrodes is supplied according to a given law, depending on the number of transparent electrodes. 5. The device according to any one of paragraphs. 1-4, characterized in that the phase filter is made in the form of a mirror. 6. The device according to any one of paragraphs. 1-4, characterized in that on the optical axis introduced a prism of total internal reflection, optically in contact with the first transparent dielectric substrate. 7. A method for suppressing speckles in laser illuminators, characterized in that the light is sequentially directed from a coherent source to a lens, modulator, Fourier lens, a phase filter located in the focus area of the Fourier lens, an output lens, and to a modulator containing a first dielectric a transparent substrate with a transparent electrically conductive layer coated with a transparent gel-like layer on one side, a second dielectric transparent substrate with an array of transparent electrodes covering the light aperture on one on the other side, voltage pulses are applied to mismatch the phase of light radiation.

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