The automatic focusing device of laser cofocal scanner
Technical field
The Electro-Optical Sensor Set field that the automatic focusing device of laser cofocal scanner belongs to is biological, medical treatment, scientific instrument are used.
Background technology
Laser cofocal scanner is compared with simple microscope, has higher resolution, is widely used in biology, life, medical treatment and the scientific instrument.Existing focusing technology and device, they are researched and developed at different technical fields, can not be applicable to laser cofocal scanner fully.As the patent No. is ZL98229444.1, the Chinese utility model patent of " focus control of lithography machine of submicron " by name discloses a kind of litho machine focus control, it is characterized by: the imaging of mark is through being carved object, little object lens, behind the catoptron, be divided into two-way by spectroscope, one road catoptric imaging is in the four-quadrant receiver, another Reuter penetrates through imagery of cylindrical mirror in ccd image sensor, two-way output defocus signal and target amount of bias are sent into single-chip microcomputer, the control piezoelectric ceramics promotes flexible hinge, drive quilt and carve the motion that object is made big displacement or micrometric displacement, reach the target position of focal plane.It does not detect and uses reflected light path, can not be used for the laser cofocal scanner of detection of biological chip.
Goal of the invention
The object of the present invention is to provide a kind of automatic focusing device that can be used for the laser cofocal scanner that biochip test uses.
The invention is characterized in: described optical scanning head contains the input path that is made of laser instrument, pin hole, lens, object lens and sample successively, and the focusing that is made of above-mentioned sample and object lens, spectroscope, astigmatic lens and four-quadrant photo detector is with reflected light path and the detection reflected light path that is made of above-mentioned sample and object lens, dichroic beamsplitter, lens, pin hole and photomultiplier successively successively; Described focusing control circuit is to serve as the digital control circuit of main formation with digital signal processing circuit and actuating motor; Described focus adjusting mechanism is the leading screw-nut type mechanical focusing mechanism of joining with the actuating motor output shaft.The amplification that described focusing control circuit is linked to each other with the output terminal of above-mentioned four-quadrant photo detector by its input end successively, filtering and A/D change-over circuit, digital signal processor DSP, photoelectricity isolation, D/A conversion, amplifying circuit and actuating motor serial connection form.Described digital signal processor DSP links to each other with computing machine.Described leading screw-nut type mechanical focusing mechanism is contained: motor base, support and the fixing mounting plate of slide block are housed, pass leading screw and nut that motor base, support are connected with the output shaft of motor by shaft joint, link to each other with nut and be connected one and can move and opposite side is equipped with the removable bottom that optical scanning head is a camera lens, be contained in the photoelectric sensor on the said fixing slide block with respect to the said fixing slide block.
Use proof: it has reached intended purposes.
Description of drawings
Fig. 1~Fig. 2: the index path of two embodiment of optical scanning head in the laser cofocal scanner.
Fig. 3: the circuit theory block scheme of focusing control circuit.
Fig. 4: the mechanical principle block diagram of leading screw-nut type focus adjusting mechanism.
Embodiment
Ask for an interview Fig. 1.Laser instrument 1 is near pin hole 2, be placed on the front focal plane of lens 3, laser projects lens 3 through pin hole 2 and becomes directional light, and object lens 6 vertical irradiations of process spectroscope 4, dichroic beamsplitter 5, large-numerical aperture excite the biological sample on the biochip 8 to send fluorescence to biochip 8.Reflected light is made up of the incident laser of fluorescence that ejects from biological sample and reflection.Reflected light becomes directional light through object lens 6, after arriving dichroic beamsplitter 5, be divided into two-beam: the fluorescence that first bundle only ejects from biological sample is reflexed on the lens 3 by dichroic beamsplitter 5, image in pin hole 2, detected by immediate photomultiplier tube 10; Second bundle is laser light reflected from the biological sample only, during by dichroic beamsplitter 5, is transmitted on the spectroscope 4, reflexes on the astigmatic lens 11, images on the four-quadrant photo detector 12.Suitably select the focusing parameter of the both direction of astigmatic lens 11, can obtain certain focusing range and certain focusing accuracy.The object lens 6 of large-numerical aperture of focusing usefulness be fixed on can portable plate 7 by driven by motor on, biochip 8 is placed on the sample retainer 9.
Goodbye Fig. 2.The laser of part incident sees through biological sample 8, become directional light through lens 3, change direction through a spectroscope 4 again, arrive astigmatic lens 11 at last and image in four-quadrant photo detector 12, focusing parameter when the both direction of selecting astigmatic lens 11 can obtain certain focusing range and certain focusing accuracy.The lens 3 of focusing usefulness be fixed on can portable plate 7 by driven by motor on, biochip 8 is positioned on the sample retainer 9.
Goodbye Fig. 3.Four-quadrant photo detector 12 becomes the above-mentioned conversion of signals that receives four road electric signal amplifiers 13, wave filter 14 and A/D analog to digital converter 15 to enter digital signal processor 16 and computing machine 17, calculates and store the out of focus information of each analyzing spot.Then, mobile example in predetermined scanning area just can obtain the out of focus information of each point in the zone.When these points are all in the scope that can focus, target amount of bias according to digital signal processor 16 or computing machine 17 internal memories, send the automatic focusing order by digital signal processor 16 or computing machine 17, remove to drive actuating motor 21 by photoelectric isolation module 18, D/A digital to analog converter 19 and motor-driven power amplification circuit 20, drive focus adjusting mechanism and focus.
In Fig. 4, leading screw 22 is linked on the mounting plate 24 by support 23, and fixedly slide block 25 also is installed on the mounting plate 24, and camera lens 26 usefulness nuts are fixed on the removable bottom 27.Camera lens 26, removable bottom 27, movable guiding rail 28 and nut 29 connect together form can be up and down parts.Actuating motor 21 drives leading screw 22 by shaft joint 30 and rotates, thereby nut 29 is moved up and down along leading screw 22, drive camera lens 26 and move up and down along the optical axis direction, up to biochip 8 and on sample meet the requirements of the target focal plane position, finish the focusing operation.Photoelectric sensor 31 is fixed on fixedly on the slide block 25, plays the effect of positioning limit, avoids camera lens 26 and biochip 8 collisions, and the initialization of also can focus when hardware meets accident is located.
It can be with the mode detection of biological sample of automatic focusing, has that focusing range is big, advantage of high precision.