EP2619620A1

EP2619620A1 - Microscope illuminating system and microscope

Info

Publication number: EP2619620A1
Application number: EP11785407.5A
Authority: EP
Inventors: Michael Stockmann; Detlef Gerhard; Ralf Heim; Anton Schick
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2010-11-23
Filing date: 2011-11-18
Publication date: 2013-07-31
Also published as: WO2012069367A1; DE102010061786A1

Abstract

The microscope illuminating system (1) has at least one semiconductor light source (2) and at least one light mixing element (3) with at least one light inlet surface (4) and at least one light outlet surface (5). The at least one light inlet surface (4) is equipped and arranged to inlet light (L) of the at least one semiconductor light source (2), and the light outlet surface (5) is rectangular. Light (6) exiting the light outlet surface (5) is substantially homogenous. The microscope (M) has at least one microscope illuminating system (1) and at least one TDI sensor (N) for receiving an image.

Description

description

The invention relates to a microscope illumination, comprising at least one light source and at least one Lichtmischele ^¬ ment with at least one light entrance surface and at least one light ^exit surface, wherein the at least one light ^¬ entrance surface for the entry of light of the at least one light source is set up and arranged and from the

Light exit surface emitted light is substantially homo ^¬ conditions. The invention further relates to a microscope with at least ^¬ least such a microscope illumination and at least one TDI sensor for image recording.

In semiconductor manufacturing, a quality is finished

Circuits visually inspected with a microscope. Thus ei ^¬ ne quality control can be performed reliably and as quickly as possible, it is done by means of an auto- matic optical inspection. A required high speed of image capture can be used with line scan cameras he ^¬ enough that receive an image of being inspected Whether ^¬ jekts, as it moves under the microscope before ^¬ at. The line cameras support this Objektbewe- supply through use of so-called. TDI ( "Time Delayed Integ ^¬ ration") sensors. This type of sensor integrates the signals of objects at a constant speed over a predetermined period of time, thus providing a sensitivity required for a short exposure time. Despite the high sensitivity of the TDI sensors, the objects must be intensively illuminated because of the typically very short exposure times. For this purpose, high-pressure gas discharge lamps have hitherto been used. It is the object of the present invention to provide improved illumination for a microscope, in particular for use in quality control. This object is achieved according to the features of the independent claims. Preferred shapes are Out guide insbesonde ^¬ re gathered from the dependent claims. The object is achieved by a microscope illumination or microscope illumination device, comprising at least one semiconductor light source and at least one light mixing element with at least one light entry surface and at least ei ^¬ ner light exit surface, wherein the at least one light entry surface for the entry of light of at least one

Semiconductor light source is arranged and arranged, the light exit surface is rectangular and the light emerging from the light ^¬ exit surface light has a substantially homogeneous intensity distribution. The intensity distribution depends on the application. In a typical application, the absolute intensity variation of light from ^¬ tread surface is based less than 5%, in particular less than 1%. This microscope illumination has the advantage that its life can be increased from previously about 500 hours to typically 10,000 hours. In addition, there are the advantages that a microscope illumination is made possible with a particularly compact design, that by a variation of a number of semiconductor light sources, a luminous flux up to a maximum value, which is determined by the size of the surface to be tested and the aperture of Mikroskopob ektives is scalable and that by a variation of an arrangement of the semiconductor light sources, a shape of a Lichtzeugungs- surface is flexible designable. In particular, if a one ^¬ zelne semiconductor light source can not produce the luminous flux and / or a power density of a gas discharge lamp, a plurality of semiconductor light sources can be used for illumination.

The light mixing element may, in particular, be an optical element which mixes light entering through its light entrance surface in its interior, so that the light is compared to the light. moderately emerges from the light exit surface. In this case, the homogenization may comprise a homogenization of a light intensity and, in the case of differently colored incoming light, a light color.

Preferably, the at least one semiconductor light source ^¬ comprises at least one light emitting diode. If several LEDs are present, they can be lit in the same color or in different colors. A color can be monochrome (eg red, green, blue, etc.) or multichrome (eg, white). The light emitted by the at least one light-emitting diode can also be an infrared light (IR LED) or an ultraviolet light (UV LED). Several light emitting diodes can produce a mixed light; z. B. a white mixed light. The at least one light-emitting diode may contain at least one wavelength-converting phosphor (conversion LED). The at least one light-emitting diode can be present in the form of at least one individually ge ^¬ ned LED or in the form of at least one LED chip. Several LED chips can be mounted on a common substrate ("submount"). The at least one light emitting diode may be equipped with at least one own and / or ge ^¬ common optics for beam guidance, z. At least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic light emitting diodes, z. Based on InGaN or AlInGaP, organic LEDs (OLEDs, eg polymer OLEDs) can generally also be used. Alternatively, the at least one semiconductor light source z. B. Minim ^¬ least comprise a diode laser.

It is an aspect that the microscope comprises a plurality of illumination disposed in at least one row or row ^¬ semi-conductor light sources, especially light-emitting diodes. The shape of the row is adapted to a shape of an area or object line to be illuminated during an inspection. Thus, it can in that a light emitting surface or emission surface ^¬ is assembled from individual sources emitter areas of a plurality of semiconductor light ^¬, the shape of the emission surface of the shape of the illuminated surface of the object or the mold a light receiver (in particular a camera) correspond at least in principle. This arrangement of the semiconductor light sources allows a much more effective illumination of the object line than by means of the gas discharge lamp. Co- means of the gas discharge lamp can only be a circular Whether ^¬ jektfeld be illuminated, of which only a rectangular cut along the circle diameter is used. Therefore, it is possible to achieve a higher luminance than the object with the gas discharge lamp with the adjusted Halbleiterlichtquellenbe ^¬ lighting, despite a possibly low ^¬ ren output light current of the semiconductor light sources as compared with the gas discharge lamp.

The semiconductor light sources can be arranged in one or more, in particular parallel, rows.

It is a development that the light mixing element is a cuboid light mixing element. This allows a particularly effective mixing of light, in particular for row-shaped semiconductor light sources.

It is still an embodiment that the light mixing element is a totally reflecting body for the light. The light mixing element thus reflects the light traveling in it on its lateral surface (ie in particular a surface of the light mixing element except the light entrance surface and the light exit surface) due to total reflection. This he ^¬ allows a particularly low-loss light guide. The total reflecting body can be a Glaskör ^¬ per particular.

The circumferential surface may be ^¬ telschicht is at least partially with a Man.

Alternatively, a lateral surface of the light mixing ^element may be provided with a reflective coating at least in regions. Alternatively, or in addition to the totally reflecting body as the light mixing member comprises a diffusion plate as the light ^¬ mixing element in an illumination beam path may be present.

It is an especially preferred for quality control in the Halbleiterfer ^¬ actuating configuration that the micro ^¬ skopbeleuchtung has three to fifteen, and in particular five to ten, are arranged in a number of semiconductor light sources up. As a result, a sufficient illuminance is made possible with little effort.

It is yet a further embodiment that the at least one semiconductor light source is a respective light-emitting diode chip (LED chip). The LED chips can be densely packed as opposed to individually packaged LEDs, allowing a particularly compact and homogeneous radiating emission ^¬ surface. It is a further advantageous embodiment, that an aspect ratio ^¬ the light entry surface and the light exit surface ^¬ between about 5: 1 and about 10: 1.

It is also an advantageous embodiment that a width B of the light entry surface and the light exit surface Zvi ^¬ rule about 5 mm and about 10 mm and a corresponding height H is approximately 1 mm.

It is also an embodiment that a depth T or length of the light mixing element is at least 10 mm, in particular between about 50 mm and about 100 mm. Thus, a still compact design can be achieved with a good light mixture at the same time. The deeper or longer the light mixing element is selected, the better the light mixture will be. In general, a fluctuation of the luminous flux or the

Light intensity preferably be kept in a range of 1% or less. The object is also achieved by a microscope having at least one microscope illumination as described above and at least one TDI sensor for image acquisition. However, the invention is not limited to TDI sensors and may, for. B. also include conventional pixel sensors such as CCD sensors, etc.

In the following figures, the invention will be described schematically with reference to an imple mentation example. It Kings nen for clarity identical or equivalent Elemen te be provided with the same reference numerals.

Fig. 1 outlines a basic structure of a microscope for

Quality control;

Fig. 2 shows a sectional view in side view of a

Microscope illumination with a gas discharge lamp as a light source according to the prior art; Fig. 3 shows a microscope illumination according to the invention in a plan view; and

4 shows the microscope illumination according to the invention in a side view.

Fig.l outlining a basic structure of microscope M to Qua ^¬ surance. The microscope M has a microscope illumination (device) I, which has a light source Q. From the light source Q light L is irradiated in the form of a trade Strahlbün ^¬ a semipermeable mirror S and where it is reflected towards a sample to be inspected P. In this case, a Mikroskopob ektiv 0 is introduced between the semipermeable mirror S and the sample P.

The sample P is located in an ob ect area OB of the microscope M and is moved linearly by means of a positioning unit V through the object area OB. On the sample P auftref- fendes light L is rejected by the Mikroskopob ektiv 0 zurückge ^¬ , passes through the unreflective semipermeable mirror S and applies to a line scan camera in the form of a TDI camera K with at least one TDI sensor N.

The TDI camera K supplies data for evaluation to a data processing unit A, which also includes a driver D for the movement unit V and a controller C for the TDI camera K (for a camera control or regulation) and the microscope objective 0 (for a Focus control or regulation). The driver D and the controller C can also communicate with each other.

2 is a sectional side view of a microscope illumination I with a gas discharge lamp G as the light source Q according to the prior art. An elliptical mirror R focuses the light emitted by a gas discharge area GD of the gas discharge lamp G light L to a serving as the egg ^¬ ne light entry surface Li end face of a glass rod GS with a circular cross-section. By Totalre ^¬ flexion within the glass rod GS, the light L is mixed and exits with a uniform distribution over the cross section at a serving as a light exit surface Lo ent ^¬ against opposite end face. A downstream Mikroskopob- objectively 0 forms the ausgetre from the light exit surface Lo ^¬ tene light distribution from the object OB area in which the object to be illuminated, the sample P is located.

Corresponding to the shape of the rod end, the illuminated object region OB is circular in plan view, as indicated by the right partial image. However, since the line camera K sees only a rectangular cut-out (by a chain line angedeu ^¬ tet) the light L, which falls within the county area outside the rectangular area can not advertising used to. 3 shows a microscope illumination 1 according to the invention in a plan view and FIG. 4 shows the microscope illumination 1 in a side view. The microscope illumination 1 includes five LED chips 2 with jeweili ^¬ gen emitter areas of about 1 mm x 1 mm, which are disposed closely adjacent in a row or line. A Aspektver ^¬ ratio of common emission range of 5 mm x 1 mm be ^¬ thus contributes approximately 5: 1. It is preferable that the aspect ratio of the series as well as possible corresponds to an aspect ratio of rows ^¬ camera K, in particular of the TDI sensor N.

A light mixing element 3 in the form of a glass cuboid is connected downstream of the LED chips. The light mixing element 3 has a light ^entry surface 4 facing the LED chips 2 (end face of the cuboid) and a light exit surface 5 with the dimensions B x H = 5 mm x 1 mm formed by the end face facing away from it. The light entrance surface 4 and the Lichtaustrittsflä ^¬ che 5 thus have the same rectangular shape with a aspect ratio of about 5: 1 on. The length or depth T of the

Light mixing element 3 is 50 mm to 100 mm. In the light ^¬ mixing element 3, incident light from the LED chip 2 L is mixed so that the light L emerges high ^¬ gradig uniformly distributed over the surface on the light exit surface. 5

The Mikroskopob ektiv 0 downstream of the light mixing element 3 forms the rectangular light exit surface 5 on the Ob ^¬ jektbereich 6 and illuminates the area that the Keilenka ^¬ mera K, in particular TDI sensor N, sees. Therefore, in contrast to the illumination with the gas discharge lamp G, a much higher part of the light incident on the object area 6 is used.

As an example of the superiority of the microscope illumination 1 of the invention, an optical simulation of the microscope illumination M with the gas discharge lamp G on the one hand and with the light emitting diodes 2 is now described as the light source Q walls hand, ^¬. The gas discharge lamp G in this ^example is a xenon high-pressure lamp with an output ^light current of the plasma of 10,000 Im. The microscope objective 0 with a numerical aperture of 0.15 illuminates the object region OB. On a used rectangular area of, for example, 4.6 mm by 0.14 mm of the object area OB, light still strikes with 5 lumens (Im). For the microscope illumination 1, five individual LEDs 2 are combined into a row with the area of 5 mm × 1 mm. A total luminous flux of the LEDs 2 is 3900 Im. The imaging microscope objective 0 and the sensed rectangular Whether ^¬ jektbereich are those of the example of Gasentladungslam- pe G equal. From the luminous flux of the LEDs 2 of 3900 Im reach 10 Im on the rectangular object area 6. The ratio of usable luminous flux to a total luminous flux of the light source G or 2 is about five times higher in the LED illumination than in the illumination with the Gas discharge lamp G.

Of course, the present invention is not limited to the embodiment shown.

Claims

claims

1. microscope illumination (1), comprising

- At least one semiconductor light source (2) and

- at least one light mixing element (3) with at least one light entry surface (4) and at least one light output ^¬ tread surface (5),

in which

- The at least one light entry surface (4) for the entry of light (L) of the at least one semiconductor light source

(2) is set up and arranged and

- The light exit surface (5) is rectangular and the light emerging from the light exit surface (5) light (L) has a substantially homogeneous intensity distribution.

2. microscope illumination (1) according to claim 1, comprising a plurality of arranged in at least one row semiconductor light sources ^¬ (2), wherein the light mixing element (3) is a cuboid light mixing element.

3. microscope illumination (1) according to claim 2, wherein the light mixing element (3) is a totalre for the current in it light ^¬ inflectional body.

4. microscope illumination (1) according to any one of the preceding claims, comprising three to fifteen, in particular five to ten, arranged in a row semiconductor light sources (2).

5. microscope illumination (1) according to one of the preceding claims, wherein the at least one semiconductor light source (2) is a respective light-emitting diode chip.

6. microscope illumination (1) according to one of claims 2 to 5, wherein an aspect ratio of the light entry surface (4) and the light exit surface (5) between about 5: 1 and about 10: 1.

7. microscope illumination (1) according to any one of the preceding claims, wherein a width (B) of the light entry surface (4) and the light exit surface (5) between about 5 mm and about 10 mm and an associated height (H) is about 1 mm.

8. microscope illumination (1) according to any one of the preceding claims, wherein a depth (T) of the light mixing element (3) min ^¬ least 10 mm, in particular between about 50 mm and about 100 mm.

9. microscope (M), comprising at least one Mikroskopbe ^¬ illumination (1) according to one of the preceding claims and at least one TDI sensor (N) for image acquisition.