CN216696836U - Laser uniform illumination system and light guide pipe - Google Patents
Laser uniform illumination system and light guide pipe Download PDFInfo
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- CN216696836U CN216696836U CN202122220861.9U CN202122220861U CN216696836U CN 216696836 U CN216696836 U CN 216696836U CN 202122220861 U CN202122220861 U CN 202122220861U CN 216696836 U CN216696836 U CN 216696836U
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Abstract
The laser uniform illumination system and the light guide pipe provided by the embodiment of the application adopt the light guide pipe with the isosceles trapezoid cross section, the light guide pipe at least comprises one sub light guide pipe with the isosceles trapezoid cross section, all the sub light guide pipes are sequentially overlapped together from top to bottom, the top edge of the sub light guide pipe cross section positioned at the top is the top edge of the light guide pipe cross section, and the bottom edge of the sub light guide pipe cross section positioned at the bottom is the bottom edge of the light guide pipe cross section; between any two adjacent sub-light pipes, the bottom side of the cross section of the sub-light pipe positioned above is attached to the top side of the cross section of the sub-light pipe positioned below, and the lengths of the sub-light pipes are consistent. The application provides a laser uniform lighting system sets up the cross section of light pipe into isosceles trapezoid, utilizes imaging lens's imaging principle, and the height ratio of the light intensity is close to one on the control surveyed sample surface, improves the homogeneity of light intensity distribution.
Description
Technical Field
The application relates to the technical field of laser illumination imaging, in particular to a laser uniform illumination system and a light guide pipe.
Background
The high-flux optical fluorescence biochemical application system generally comprises a detection module, a large-area tested sample and a laser illumination system, wherein the detection module can be a high-resolution optical microscope, the area of the tested sample can be more than 10mmx10mm, and the laser illumination system generally adopts a high-power laser light source. After the laser light source is transmitted through the light guide pipe and the imaging lens, the laser light source irradiates the surface of the measured sample, and the higher the light intensity distribution height ratio (namely the ratio of the highest light intensity to the lowest light intensity, HLR) formed on the surface of the measured sample is, the closer to one, the better the optical imaging quality is, the more favorable the observation of a microscope is.
Since the optical system of the microscope is usually along the normal direction of the area where the surface of the sample is located, when the laser light is incident through the light guide, the laser light must be obliquely incident on the sample in the direction deviating from the normal direction, and sometimes the laser light may be obliquely incident at a relatively large angle in order to avoid being blocked by the objective lens, which results in forming an oblique light intensity distribution on the surface of the sample, and the height ratio of the light intensity distribution on the surface of the sample becomes higher and higher as the area of the sample increases.
If the height ratio of the light intensity distribution on the surface of the sample to be detected is higher, the light intensity distribution is not uniform, so that the energy difference of the laser received by the sample to be detected is large, the consistency of light signals generated by the subsequent sample to be detected is influenced, and the detection of a microscope is not facilitated.
SUMMERY OF THE UTILITY MODEL
In order to solve the technical problem that the light intensity distribution formed on the surface of a detected sample is uneven due to the fact that the surface of the detected sample is not perpendicular to a light path, the application discloses a laser uniform illumination system and a light guide pipe through the following embodiments.
The application discloses in a first aspect, a laser homogeneous illumination system, including: the device comprises a laser, a light guide pipe, an imaging lens and a detected sample; the laser emitted by the laser sequentially passes through the light guide pipe and the imaging lens and irradiates the surface of the sample to be measured;
the cross section of the light guide pipe is in an isosceles trapezoid shape, a first height value is arranged between the bottom edge of the cross section of the light guide pipe and the optical axis, a second height value is arranged between the top edge of the cross section of the light guide pipe and the optical axis, the height of the cross section of the light guide pipe is the sum of the first height value and the second height value, and the optical axis is a straight line formed by connecting the center of the imaging lens and the center of the irradiated area on the surface of the measured sample;
the light guide pipe at least comprises a sub light guide pipe, and the cross section of the sub light guide pipe is in an isosceles trapezoid shape;
if the light guide pipe comprises more than two sub light guide pipes, all the sub light guide pipes are sequentially overlapped up and down, the top edge of the cross section of the sub light guide pipe positioned at the top is the top edge of the cross section of the light guide pipe, and the bottom edge of the cross section of the sub light guide pipe positioned at the bottom is the bottom edge of the cross section of the light guide pipe;
between any two adjacent sub-light pipes, the bottom side of the cross section of the sub-light pipe positioned above is attached to the top side of the cross section of the sub-light pipe positioned below, and the lengths of the sub-light pipes are consistent.
Optionally, the length of the bottom edge of the cross section of the light guide pipe is the ratio of the width of the irradiated area on the surface of the measured sample to the first vertical axis magnification; the first vertical axis magnification is a ratio of a far-end distance value to a light guide distance value, the far-end distance value is a farthest distance value between the imaging lens and an irradiated area on the surface of the detected sample, and the light guide distance value is a distance value between the imaging lens and a light emergent end face of the light guide pipe;
the length of the top edge of the cross section of the light guide pipe is the ratio of the width of the irradiated area on the surface of the measured sample to the second vertical axis magnification; the second vertical axis magnification is a ratio of a near-end distance value to the light guide distance value, and the near-end distance value is a closest distance value between the imaging lens and the illuminated area on the surface of the measured sample.
Optionally, the first height value is
The second height value is
Wherein, B is the length of the surface of the tested sample, alpha is the included angle between the central normal of the surface of the tested sample and the optical axis, and beta1For said first homeotropic magnification, β2Is the second homeotropic magnification.
Optionally, an included angle between the central normal of the surface of the measured sample and the optical axis is between (30 ° and 90 °).
Optionally, the light-emitting end surface of the light guide tube is an inclined plane, and the lower edge of the light-emitting end surface is more protruded than the upper edge;
the included angle between the light-emitting end face of the light guide pipe and the longitudinal vertical face is set according to the object image relationship of the imaging lens, the focal length of the imaging lens, the first height value, the second height value, the far-end distance value and the near-end distance value.
Optionally, the light guide distance value includes a near light guide distance value and a far light guide distance value; the near light guide distance value is a distance value between the lower edge of the light outlet end face of the light guide pipe and the imaging lens, and the far light guide distance value is a distance value between the upper edge of the light outlet end face of the light guide pipe and the imaging lens.
Optionally, the first vertical axis magnification is a ratio between the distal end distance value and the near light guiding distance value;
the second homeotropic magnification is a ratio between the proximal distance value and the distal optical distance value.
Optionally, if the light guide pipe includes N sub light guide pipes, the height of the cross section of each sub light guide pipe is:
wherein h is1、h2、…、hN-1And hNThe height of N sub-light guide pipes from bottom to top is sequentially arranged, b is the height of the cross section of the light guide pipe, a1Representing the base of the light pipe cross-section, a2Representing the top edge of the light pipe cross-section.
The second aspect of the present application discloses a light pipe, the light pipe is the first aspect of the present application the light pipe in the laser uniform lighting system.
Optionally, antireflection films are arranged on the light incident end face and the light emergent end face of the light guide tube.
The laser uniform lighting system and the light guide pipe provided by the embodiment of the application adopt the light guide pipe with the cross section being the isosceles trapezoid shape, and the light guide pipe at least comprises a sub light guide pipe with the cross section being the isosceles trapezoid shape, because the imaging of the surface of the tested sample is the reverse image, the top edge of the light guide pipe can image the lower edge of the surface of the tested sample, and the bottom edge of the light guide pipe can image the upper edge of the surface of the tested sample. According to the inclined orientation, if the lower edge of the surface of the measured sample is closer to the imaging lens, the image distance is short, and the magnification is small, the top edge of the light guide pipe is longer than the bottom edge, so that the light intensity imaged to the lower edge of the surface of the measured sample is higher; if the upper edge of the surface of the measured sample is closer to the imaging lens, the image distance is short, and the magnification is small, the bottom edge of the light guide pipe is longer than the top edge, so that the light intensity imaged on the upper edge of the surface of the measured sample is higher. The size that combines the formation of image lens's formation of image principle and the isosceles trapezoid cross section of light pipe so sets for, and this application can effectively improve the light intensity distribution homogeneity on surveyed sample surface, and the height ratio of controlling on the surveyed sample surface light intensity is close to one, improves the homogeneity of light intensity distribution.
Drawings
FIG. 1 is a schematic view of a laser illumination system with a surface of a sample to be measured perpendicular to a projection light path;
FIG. 2 is a schematic diagram of a laser illumination system in which the surface of a sample to be measured is not perpendicular to the projection optical path;
fig. 3 is a schematic structural diagram of a light pipe in the laser uniform illumination system disclosed in the embodiment of the present application;
FIG. 4 is a schematic diagram of an image projection optical path of a laser homogeneous illumination system disclosed in an embodiment of the present application;
FIG. 5 is a schematic view of an amplification effect of a light pipe and an imaging lens in an image projection light path of the laser uniform illumination system disclosed in the embodiment of the present application;
FIG. 6 is a schematic structural diagram of a light pipe composed of a plurality of sub-light pipes in the laser uniform illumination system disclosed in the embodiment of the present application;
fig. 7 is a schematic structural view illustrating a light exit end surface of a light pipe being an inclined plane in an image projection light path of the laser uniform illumination system disclosed in the embodiment of the present application;
fig. 8 is a schematic structural view of a light pipe composed of two sub-light pipes in the laser uniform illumination system disclosed in the embodiment of the present application;
fig. 9 is a schematic structural view of a light guide tube composed of three sub light guide tubes in the laser uniform illumination system disclosed in the embodiment of the present application.
Detailed Description
In order to facilitate the technical solution of the present application, some concepts related to the present application will be described below.
In the existing standard image projection light path, laser light emitted by a laser 101 is transmitted through a light guide tube 102 and an imaging lens 103 to form a light path 105, and the light path is projected on the surface of a measured sample 104. Referring to fig. 1, the surface of the measured sample 104 is perpendicular to the light path 105, in this case, the cross section of the light guide 102 may be a square with a side length of 1mm, and the length of the light guide 102 may be 50 mm. Since the light pipe with the square light passing section has the light uniformizing function, the light intensity distribution of the image projected on the surface of the measured sample 104 is close to unity. In this application, the height ratio (HLR) refers to the ratio between the highest light intensity and the lowest light intensity of the illuminated area on the surface of the sample to be measured.
In the present application, the optical path is also referred to as an optical axis, and is a straight line formed by connecting the center of the imaging lens and the center of the irradiated region on the surface of the sample to be measured.
When the surface of the measured sample 104 is not perpendicular to the optical path 105 any more but is inclined by an angle α, as shown in fig. 2, the image projected on the surface of the measured sample is distorted and deformed to form an inclined light intensity distribution, so that the height ratio of the light intensity distribution is greater than 1, and the value of the height ratio of the light intensity distribution is greater as the value of α increases or the surface area of the measured sample increases.
In order to solve the technical problem that the light intensity distribution formed on the surface of a detected sample is uneven due to the fact that the surface of the detected sample is not perpendicular to a light path, the application discloses a laser uniform illumination system and a light guide pipe through the following embodiments.
A first embodiment of the present application discloses a laser homogeneous illumination system, the configuration of which substantially corresponds to the configuration shown in fig. 2, including: a laser 101, a light pipe 102, an imaging lens 103 and a sample 104 to be measured; the laser emitted from the laser 101 sequentially passes through the light guide tube 102 and the imaging lens 103, and irradiates the surface of the sample 104.
Compared with the conventional laser illumination system, the most important difference of the laser uniform illumination system provided by the embodiment is the structure of the light guide pipe. Referring to fig. 3, the cross section of the light pipe in this embodiment is an isosceles trapezoid, the size of the light pipe is set according to various parameters in the illumination system, and different illumination areas are required in different application scenes, so that the size of the light pipe is different, specifically according to the requirement and the amplification ratio of the projection light path. In order to correct the distortion of the irradiated area on the surface of the sample to be measured, the dimensions of the upper and lower sides of the cross section of the light guide tube and the height of the cross section of the light guide tube are determined according to the simulation result, which will be described in detail below.
It should be noted that, in the present general definition, two parallel sides of an isosceles trapezoid are called the bottom sides of the trapezoid, wherein the longer bottom side is called the bottom side and the shorter bottom side is called the top side, which is not applicable in the present application, because the description of the cross-sectional dimension of the light guide in the present application will have orientation and length limitations, and if the longer bottom side of a panel is called the bottom side, it will be unclear, and in order to prevent ambiguity, in the present application, once the position of the light guide in the illumination system is well defined, the upper side is called the top side and the lower side is called the bottom side with respect to the cross-section of the light guide. Referring to FIG. 3, the first side is the top side, and the second side is the bottom side.
The light pipe includes two ports, is laser incident port and laser outgoing port respectively, and in this embodiment, the terminal surface that corresponds with laser incident end is called into the light terminal surface, and the terminal surface that corresponds with the laser outgoing end is called out the light terminal surface. Referring to fig. 4, the distance between the light-emitting end surface of the light guide 102 and the center of the imaging lens 103 is L. The distance between the center of the imaging lens 103 and the center of the irradiated area of the surface of the measured sample is L ', wherein L' is far larger than L.
The surface of the sample to be measured is a rectangular surface with a size of a × B, a width of a, and a length of B. The illuminated area of the measured sample surface can be seen as the projected rectangular area shown at the rightmost side in fig. 4, with the size a × C, the width a, and the length C, which can be obtained based on the projection principle, where C is B × cos (α).
In practical applications, the imaging lens 103 is a positive lens with a focal length F', and the imaging lens may be a single lens or a combination of multiple lenses. The sizes of L ', L and F' are set by technicians according to actual needs.
Fig. 5 is a schematic diagram of positions between the light guide, the imaging lens and the sample to be measured in this embodiment, and it should be noted that, in order to clearly show the positional relationship between the light guide and the imaging lens, the light guide and the imaging lens in the dashed line frame are enlarged effect diagrams, and the isosceles trapezoid between the light guide 102 and the imaging lens 103 is not a solid component, but a cross section of the light guide 102.
In FIG. 5, the length of the bottom side of the cross section of the light pipe is a1The length of the top edge is a2The distance between the bottom edge of the cross section of the light pipe and the optical axis is a first height value b1And the distance between the top edge of the cross section of the light guide pipe and the optical axis is a second height value b2The height of the cross section of the light pipe is the first height value b1And the second height value b2And the optical axis is a straight line formed by connecting the center of the imaging lens and the center of the irradiated area on the surface of the measured sample.
The coupling modes of the laser are various, and the key point of the coupling is to focus the light spot of the laser to the end surface of the complete light guide pipe, and the incident angle can meet the requirement of total reflection in the light guide pipe. For example, a semiconductor laser diode is coupled into a light pipe through collimation and focusing. For the fiber output laser, if the end face of the fiber can be contained by the end face of the light guide pipe, the laser divergence angle of the fiber output is appropriate (satisfying the total reflection inside the light guide pipe), and the fiber output laser can be directly butted with the light guide pipe. The manner in which laser light is coupled into a light pipe is similar to the method of coupling into an optical fiber and there are many papers and patents that describe this method of coupling and are not discussed here.
With reference to fig. 3 and 6, the light guide tube at least includes one sub light guide tube, and the cross section of the sub light guide tube is an isosceles trapezoid. If the light guide pipe comprises more than two sub light guide pipes, all the sub light guide pipes are sequentially overlapped together from top to bottom, the top edge of the cross section of the sub light guide pipe positioned at the top is the top edge of the cross section of the light guide pipe, and the bottom edge of the cross section of the sub light guide pipe positioned at the bottom is the bottom edge of the cross section of the light guide pipe.
Between any two adjacent sub-light pipes, the bottom side of the cross section of the sub-light pipe positioned above is attached to the top side of the cross section of the sub-light pipe positioned below, and the lengths of the sub-light pipes are consistent.
Fig. 6 shows a light guide structure diagram composed of two sub light guides on the left, and a light guide structure diagram composed of three sub light guides on the right. When the light pipe includes more than two sub-light pipes, all sub-light pipes are overlapped together from top to bottom in proper order to form the whole light pipe, and the sum of the heights of all sub-light pipes is equal to the height of the whole light pipe.
The even lighting system of laser that this application first embodiment provided has adopted the cross section to be isosceles trapezoid's light pipe, and the light pipe includes at least that a cross section is isosceles trapezoid's sub-light pipe, because the formation of image on measured sample surface is the back image, so the top edge of light pipe will be imaged the lower level on measured sample surface, and the base of light pipe will be imaged the higher authority on measured sample surface. According to the inclined direction, if the lower edge of the surface of the measured sample is closer to the imaging lens, the image distance is short, and the magnification is small, the top edge of the light guide pipe is longer than the bottom edge, so that the light intensity imaged to the lower edge of the surface of the measured sample is higher; if the upper edge of the surface of the measured sample is closer to the imaging lens, the image distance is short, and the magnification is small, the bottom edge of the light guide pipe is longer than the top edge, so that the light intensity imaged on the upper edge of the surface of the measured sample is higher. The size that combines the formation of image lens's formation of image principle and the isosceles trapezoid cross section of light pipe so sets for, and this application can effectively improve the light intensity distribution homogeneity on surveyed sample surface, and the height ratio of controlling on the surveyed sample surface light intensity is close to one, improves the homogeneity of light intensity distribution.
Referring to fig. 7, since the surface of the measured sample is inclined, different horizontal distances exist between the central line of the imaging lens and the irradiated area of the surface of the measured sample, in this embodiment, the farthest horizontal distance and the closest horizontal distance, i.e. L in the drawing, are mainly used in defining the size of the cross section of the light guide1' and L2', wherein L1Is called as a far-end distance value, wherein the far-end distance value is the farthest distance value between the imaging lens and the irradiated area of the surface of the measured sample, L2' is called a near-end distance value, and the near-end distance value is the nearest distance value between the imaging lens and the irradiated area of the surface of the measured sample. According to FIG. 7, L,L1' and L2' the following geometric relationship is satisfied:
in one implementation, the length a of the bottom side of the light pipe cross section1The width A of the irradiated area on the surface of the measured sample and the first vertical axis magnification beta1The ratio of (a) to (b). First vertical axis magnification beta1The light guide distance value is a ratio of a far-end distance value to a light guide distance value, and the light guide distance value is a distance value between the imaging lens and the light emergent end face of the light guide pipe.
Length a of top edge of light pipe cross section2The width A of the irradiated area on the surface of the measured sample and the second vertical axis magnification beta2The ratio of (A) to (B); the second vertical axis magnification beta2Is the ratio between the proximal end distance value and the light guiding distance value.
Further, the first height value is
The second height value is
Wherein, B is the length of the surface of the tested sample, alpha is the included angle between the central normal of the surface of the tested sample and the optical axis, and beta1For said first homeotropic magnification, β2Is the second homeotropic magnification.
In one implementation, referring to fig. 5, the light exit end surface of the light guide tube 102 is set to be a vertical plane, and the energy uniformity of the irradiated area can be improved and the height-to-height ratio of the light intensity distribution on the surface of the sample to be measured can be reduced by utilizing the light uniformizing effect of the trapezoidal light guide tube.
In another implementation, referring to FIG. 7, the light exit end surface of the light pipe 102 is configured as an inclined surface, and the lower edge of the light exit end surface protrudes beyond the upper edge. In this case, an included angle phi exists between the light exit end surface of the light guide tube and the vertical surface, and the size of the included angle phi is set according to the object-image relationship of the imaging lens, the focal length of the imaging lens, the first height value, the second height value, the far-end distance value, and the near-end distance value.
Referring to fig. 7, the light guide distance values are set to include a near light guide distance value L1And a distance value L of the light beam2(ii) a The near light guide distance value L1The distance value between the lower edge of the light-emitting end face of the light guide pipe and the imaging lens is the distance value L of the distance value of the distance of2The distance value between the upper edge of the light outlet end face of the light guide pipe and the imaging lens is obtained.
The first homeotropic magnification beta1Is the value of the distance from the far end L1' and the light-guiding distance value L1The ratio therebetween.
The second vertical axis magnification beta2Is the near-end distance value L2' distance value L from said remote light guide2The ratio therebetween.
Specifically, referring to fig. 7, regarding the imaging lens as a thin lens, according to the object-image relationship, it can be obtained that:
first vertical axis magnification beta1And a second homeotropic magnification beta2Can be obtained by the following formula:
through the conversion of the formula, the following can be obtained:
in this embodiment, if L1≈L2The light pipe can ignore the reason L1，L2And (3) errors caused by different factors, wherein the light-emitting end surface of the light guide pipe is a vertical plane under the condition.
Of course, if the calculation is accurate, L can be obtained according to the object-image relation formula1，L2The value of (c):
then, the angle phi is calculated according to the following formula:
based on the formula, phi is obtained through calculation, and the light-emitting end face of the light guide pipe can be set to be an inclined plane.
Referring to fig. 7, the size of the included angle α between the central normal of the measured sample surface and the optical axis is between (30 °, 90 °).
In practical applications, if α is 90 °, the incident direction of the laser light and the surface of the sample to be measured are parallel to each other, and the projected image cannot be imaged on the surface of the sample to be measured. If α <30 °, the pattern is distorted and the degree of uniformity deterioration is low, and it is not worth to adjust it uniformly in view of cost. However, if the cost is not considered, the value range of α in the laser uniform illumination system provided by the present embodiment may be (0 °, 90 °).
Theoretically, after the light pipe is imaged on the surface of the inclined tested sample, the highest value and the lowest value of the light intensity distribution respectively correspond to the a of the light pipe2Edge and a1And (7) edge. Since the projection is an inverted image, a2Projected onto the lower edge of the surface of the sample under test, a1Projected to the upper edge of the surface of the sample being measured.
Assuming that the light energy distribution on the end surface of the light pipe is absolutely uniform, i.e. the energy density P is in the light pipe a1，a2Equal at the edge, i.e. P (a)1)＝P(a2) At this time, HLR is equal to Pmax/Pmin＝P(a2)*a2/P(a1)*a1＝a2/a1. In the formula, PmaxAnd PminAre respectively provided withThe highest light intensity and the lowest light intensity of the light guide tube in the imaging area of the surface of the measured sample are obtained. HLR of single light pipe is
Through the reasonable size that sets up the light pipe cross section, alright be close to one in order to control HLR, improve the degree of consistency to the surperficial light intensity distribution of surveyed sample.
According to the formula
Can know that a1，a2Inversely proportional to the two homeotropic magnifications, i.e. the longer the B value of the illuminated area, the larger the tilt angle α, which results in a2/a1The higher the value of (HLR).
When the light pipe includes only one sub light pipe, for example, the top edge of the cross section of the light pipe may be set to 1.8mm, the bottom edge may be set to 1.5mm, and the height may be set to 0.9 mm. It can be calculated that HLR is 1.2, so that the height ratio of the light intensity distribution on the surface of the measured sample is close to unity, and the uniformity of the light intensity distribution on the surface of the measured sample is improved.
When the light pipe comprises two sub light pipes, see fig. 8, the light pipe is divided into two sub light pipes, sub light pipe 1 and sub light pipe 2, according to the total height b direction of the light pipe.
The sub light pipe 1 and the sub light pipe 2 form respective imaging light spots, each sub light pipe has its own HLR, and the HLRs are respectively used1、HLR2And (4) showing. When the extreme values of the respective energy distributions of the two sub-light pipes are the same, i.e., P1max＝P2max，P1min＝P2minThe HLR of the integral light pipe is minimum, and the HLR is the HLR at the moment1＝HLR2. In the formula, P1maxAnd P1min、P2maxAnd P2minThe highest light intensity and the lowest light intensity of the sub-light guide pipe 1 and the sub-light guide pipe 2 in the irradiated area of the surface of the sample to be measured are respectively.
Assuming that the light energy distribution of the end surface of the sub-light pipe 1 is absolutely uniform, the energy density is P1The light energy distribution of the end surface of the sub-light guide pipe 2 is absolutely uniform, and the energy density is P2. Let the length of the top side of the sub-light pipe 1 (i.e. the bottom side of the sub-light pipe 2) be x, and a1<x<a2. It can be derived that:
by HLR1＝HLR2，P1max＝P2maxThe following can be obtained:
with HLR values from a single light pipe
Optimization is as follows
The uniformity of the light intensity distribution on the surface of the detected sample can be obviously improved.
According to
The height h of the sub-light pipe 1 can be calculated1And height h of sub-light pipe 22：
Thus, the end face structures of the two light pipes can be determined, the proportional relation of the input energy of the two light pipes can be obtained, and the input energy of the sub light pipe 1 and the input energy of the sub light pipe 2 are respectively W1And W2The end surface area is S1And S2It can be calculated that:
For example, the length of the top edge of the cross section of the sub light guide 2 may be set to 1.8mm, the length of the bottom edge may be set to 1.643mm, and the height may be set to 0.47 mm. The length of the top edge of the cross section of the sub light guide 1 can be set to 1.643mm, the length of the bottom edge can be set to 1.5mm, and the height can be set to 0.43 mm.
When the light pipe includes three sub light pipes, see fig. 9, the light pipe is divided into 3 sub light pipes, sub light pipe 1, sub light pipe 2 and sub light pipe 3, according to the total height b direction of the light pipe.
The sub light pipe 1, the sub light pipe 2 and the sub light pipe 3 form respective imaging light spots, each sub light pipe has its own HLR, and the HLR is used for the sub light pipe1、HLR2、HLR3And (4) showing. When the extreme values of the respective energy distributions of the three sub-light pipes are the same, i.e., P1max＝P2max＝P3max，P1min＝P2min＝P3minWhen the HLR is the minimum, the HLR is the HLR1＝HLR2＝HLR3. In the formula, P1maxAnd P1min、P2maxAnd P2min、P3maxAnd P3minThe highest light intensity and the lowest light intensity of the sub-light guide tube 1, the sub-light guide tube 2 and the sub-light guide tube 3 in the irradiated area on the surface of the measured sample are respectively.
Assuming that the light energy distribution of the end surface of the sub-light pipe 1 is absolutely uniform, the energy density is P1The light energy distribution of the end surface of the sub-light guide pipe 2 is absolutely uniform, and the energy density is P2The light energy distribution of the end surface of the sub light pipe 3 is absolutely uniform, and the energy density is P3. Let the length of the top side of the sub-light pipe 1 (i.e. the bottom side of the sub-light pipe 2) be x1The length of the top side of sub-light pipe 2 (i.e. the bottom side of sub-light pipe 3) is x2And a is a1<x1<x2<a2. It can be derived that:
by HLR1＝HLR2＝HLR3，P1max＝P2max＝P3maxThe following can be obtained:
the HLR value then being made up of two light pipes
Optimization is as follows
It follows that the HLR end result will be closer to unity.
According to
The height h of the light pipe 1 can be calculated1Height h of light guide 22Height h of light guide 33：
Like this, the terminal surface structure of 3 sub-leaded light pipes can be confirmed, and then can obtain the input energy proportional relation of 3 sub-leaded light pipes, and it is W respectively to set up the input energy of sub-leaded light pipe 1, sub-leaded light pipe 2 and sub-leaded light pipe 31、W2、W3The end surface area is S1、S2、S3It can be calculated that:
W1：W2：W3＝P1·S1:P2·S2:
in the formula
For example, the length of the top side of the cross section of the sub light guide 3 may be set to 1.8mm, the length of the bottom side may be set to 1.694mm, and the height may be set to 0.318 mm. The length of the top side of the cross section of the sub light guide 2 can be set to 1.694mm, the length of the bottom side can be set to 1.594mm, and the height can be set to 0.3 mm. The length of the top edge of the cross section of the sub light guide 1 may be set to 1.594mm, the length of the bottom edge may be set to 1.5mm, and the height may be set to 0.282 mm.
The more sub light pipes the light pipe includes, i.e., the more the entire light pipe is divided, the more uniform the light intensity distribution of the imaging region is. The number of divisions can be determined according to actual requirements. The above calculation results are obtained under the assumption that the light energy distribution at the end face of the light guide tube is absolutely uniform. In fact, although the light uniformity of the light pipe itself can optimize the uniformity of the light intensity distribution on the end surface of the light pipe, the uniformity of the energy distribution on the end surface can still be affected by the nature of the actual incident light spot and the length of the light pipe, which are not discussed in this application. Therefore, in practical applications, the energy ratio of the coupled laser light of each light guide is adjusted according to the actual end light intensity distribution of the light guide.
If the light pipe comprises N sub-light pipes, then the HLR will be optimized as
Based on the above discussion, the height of each of the sub light pipes' cross-section is:
wherein h is1、h2、…、hN-1And hNThe height of N sub-light guide pipes from bottom to top is sequentially arranged, b is the height of the cross section of the light guide pipe, a1Representing the base of the light pipe cross-section, a2Representing the top edge of the light pipe cross-section.
The relationship between the light pipe and the laser is optical coupling, which can be realized by some optical coupling devices, and the coupling mode can be various. Obtaining the laser with the right power ratio is realized by adjusting the output power of the laser.
If the laser power coupled into the light guide pipe is the same, the emitted laser power is also the same (assuming that the laser loss inside each light guide pipe is the same), and the larger the cross-sectional dimension of the light guide pipe is, the lower the output laser power density is.
The number of the sub light pipes can be determined according to the uniformity requirement of the irradiated area, and the higher the uniformity requirement is, the more the number of the sub light pipes is required. The calculation can be specifically obtained according to simulation. As the number of sub-lightpipes needs increase, if each sub-lightpipe is coupled with a laser diode, the number of lasers required increases accordingly. Of course, when the uniformity is optimized, the output power of the laser is adjusted, and then the proportional relation of the output power of each sub-light guide pipe is adjusted. While maintaining this power ratio, the output power of each sub-light pipe is increased or decreased, changing the brightness of the entire illuminated area.
The second embodiment of the present application provides a light pipe, the light pipe is the light pipe in the laser uniform illumination system of the first embodiment of the present application, please refer to the first embodiment for details.
The material of the light guide tube is selected according to the laser used, and the material is required to have high transmission and low absorption to the laser used. In some implementations, the light pipe is made of a light transmitting material, such as BK7 glass, fused silica glass, or the like.
And antireflection films are arranged on the light incident end face and the light emergent end face of the light guide pipe. In some cases, however, if the illumination intensity is much higher than the actual application requirement, the antireflection coating may not be applied.
Whether the side surface of the light guide pipe is coated with the film is determined according to whether the incident laser meets the total reflection angle, if the total reflection angle is met, the film coating is not needed, otherwise, the high reflection film is required to be coated.
According to the light guide tube disclosed by the embodiment, because the imaging of the surface of the measured sample is an inverted image, the top edge of the light guide tube is imaged to the lower edge of the surface of the measured sample, and the bottom edge of the light guide tube is imaged to the upper edge of the surface of the measured sample. According to the inclined orientation, if the lower edge of the surface of the measured sample is closer to the imaging lens, the image distance is short, and the magnification is small, the top edge of the light guide pipe is longer than the bottom edge, so that the light intensity imaged to the lower edge of the surface of the measured sample is higher; if the upper edge of the surface of the measured sample is closer to the imaging lens, the image distance is short, and the magnification is small, the bottom edge of the light guide pipe is longer than the top edge, so that the light intensity imaged on the upper edge of the surface of the measured sample is higher. The size that combines the formation of image lens's formation of image principle and the isosceles trapezoid cross section of light pipe so sets for, and this application can effectively improve the light intensity distribution homogeneity on surveyed sample surface, and the height ratio of controlling on the surveyed sample surface light intensity is close to one, improves the homogeneity of light intensity distribution.
The embodiments provided in the present application are only a few examples of the general concept of the present application, and do not limit the scope of the present application. Any other embodiments extended according to the scheme of the present application without inventive efforts will be within the scope of protection of the present application for a person skilled in the art.
Claims (10)
1. A laser homogeneous illumination system, comprising: the device comprises a laser, a light guide pipe, an imaging lens and a detected sample; laser emitted by the laser sequentially passes through the light guide pipe and the imaging lens and irradiates the surface of the sample to be detected;
the cross section of the light guide pipe is in an isosceles trapezoid shape, a first height value is arranged between the bottom edge of the cross section of the light guide pipe and the optical axis, a second height value is arranged between the top edge of the cross section of the light guide pipe and the optical axis, the height of the cross section of the light guide pipe is the sum of the first height value and the second height value, and the optical axis is a straight line formed by connecting the center of the imaging lens and the center of the irradiated area on the surface of the measured sample;
the light guide pipe at least comprises a sub light guide pipe, and the cross section of the sub light guide pipe is in an isosceles trapezoid shape;
if the light guide pipe comprises more than two sub light guide pipes, all the sub light guide pipes are sequentially overlapped up and down, the top edge of the cross section of the sub light guide pipe positioned at the top is the top edge of the cross section of the light guide pipe, and the bottom edge of the cross section of the sub light guide pipe positioned at the bottom is the bottom edge of the cross section of the light guide pipe;
between any two adjacent sub-light pipes, the bottom side of the cross section of the sub-light pipe positioned above is attached to the top side of the cross section of the sub-light pipe positioned below, and the lengths of the sub-light pipes are consistent.
2. The laser uniform illumination system as claimed in claim 1, wherein the length of the bottom edge of the cross section of the light guide tube is the ratio of the width of the irradiated area of the surface of the measured sample to the first vertical axis magnification; the first vertical axis magnification is a ratio of a far-end distance value to a light guide distance value, the far-end distance value is a farthest distance value between the imaging lens and an irradiated area on the surface of the detected sample, and the light guide distance value is a distance value between the imaging lens and a light emergent end face of the light guide pipe;
the length of the top edge of the cross section of the light guide pipe is the ratio of the width of the irradiated area on the surface of the measured sample to the second vertical axis magnification; the second vertical axis magnification is a ratio of a near-end distance value to the light guide distance value, and the near-end distance value is a closest distance value between the imaging lens and the illuminated area on the surface of the measured sample.
3. The laser homogeneous illumination system of claim 2, wherein the first height value is
The second height value is
Wherein B is the length of the surface of the measured sample, and alpha is the clip between the central normal of the surface of the measured sample and the optical axisAngle, beta1For said first homeotropic magnification, β2Is the second homeotropic magnification.
4. The laser homogeneous illumination system of claim 3, wherein an angle between a central normal of the surface of the sample under test and the optical axis is between (30 °, 90 °).
5. The laser uniform illumination system as claimed in claim 2, wherein the light exit end face of the light guide tube is a slanted plane, and the lower edge of the light exit end face protrudes beyond the upper edge;
the included angle between the light-emitting end face of the light guide pipe and the longitudinal vertical face is set according to the object image relationship of the imaging lens, the focal length of the imaging lens, the first height value, the second height value, the far-end distance value and the near-end distance value.
6. The laser homogeneous illumination system of claim 5, wherein the light guide distance values comprise a near light guide distance value and a far light guide distance value; the near light guide distance value is a distance value between the lower edge of the light outlet end face of the light guide pipe and the imaging lens, and the far light guide distance value is a distance value between the upper edge of the light outlet end face of the light guide pipe and the imaging lens.
7. The laser homogeneous illumination system of claim 6, wherein the first homeotropic magnification is a ratio between the distal distance value and the proximal light guide distance value;
the second homeotropic magnification is a ratio between the proximal distance value and the distal light guide distance value.
8. The laser homogeneous illumination system of claim 1 or 2, wherein if the light guide pipe comprises N sub light guide pipes, the height of each sub light guide pipe cross section is:
wherein h is1、h2、…、hN-1And hNThe height of N sub-light guide pipes from bottom to top is sequentially arranged, b is the height of the cross section of the light guide pipe, a1Representing the base of the light pipe cross-section, a2Representing the top edge of the light pipe cross-section.
9. A light pipe, wherein the light pipe is the light pipe in the laser homogeneous illumination system according to any one of claims 1 to 8.
10. The light pipe of claim 9, wherein an antireflection film is disposed on both the light entrance end face and the light exit end face of the light pipe.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
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| CN202121650621 | 2021-07-20 | ||
| CN2021216506216 | 2021-07-20 |
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| CN216696836U true CN216696836U (en) | 2022-06-07 |
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| CN202122220861.9U Active CN216696836U (en) | 2021-07-20 | 2021-09-14 | Laser uniform illumination system and light guide pipe |
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| CN (1) | CN216696836U (en) |
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