Abstract:
A microscope formed from an image sensor placed against a microchannel filter so that there is one to one correspondence between the sample and the sensor, effectively enlarging the image.

Description:
STATEMENT AS TO FEDERALLY SPONSORED RESEARCH 
     The invention described herein was made in the performance of work under NASA Contract No. 20218, and is subject to the provisions of Public Law 96-517 (35 USC 202) in which the Contractor has elected to retain title. 
    
    
     BACKGROUND 
     The basic structure of an optical microscope includes magnifying lenses and movement structure. The focus of the microscope is typically adjusted each time a sample is loaded. This is because the samples are typically slightly differently placed. This becomes extremely time-consuming, especially when there are a lot of samples. Moreover, the conventional microscope is relatively heavy because of its reliance on glass lenses, and specially-produced mechanical trays and moving devices. 
     SUMMARY OF THE INVENTION 
     In view of the above, it is an object of the present specification to provide a new design of microscope, which has a capability of being lighter weight than the conventional microscope. It is also an object to provide a system which obviates certain problems associated with focusing. 
     According to the preferred embodiment, solid state sensors are used for imaging the scene. The pixel size of current solid state sensors is already in the micron range which is close to the optical limit of a microscope. This raises the concept of making a one-on-one mapping from the sample to the pixel of the solid state sensor. This provides an electronic image that resolves at the level of pixel size. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the invention will now be described with reference to the attached drawings, in which: 
     FIG. 1 shows a first embodiment of an optical microscope that uses one-on-one mapping between sample portions and a solid state sensor, for a transparent sample; 
     FIG. 2 shows a second embodiment in which the sample is immersed in a liquid; 
     FIG. 3 shows a reflective microscope embodiment; 
     FIGS. 4A and 4B show a scanning reflective microscope on a chip embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     When highly collimated light is incident on a sample, the light scatters. The scattered light spreads in all directions, while the unscattered light follows the original direction. An appropriate filter can be used to separate the scattered light from the unscattered light. A narrow angle filter allows only photons to travel along a desired direction, here the original direction, while absorbing the photons that travel along other directions. If such a filter is placed behind a sample, only the unscattered light passes through the filter. The rest of the light is absorbed. 
     FIG. 1 shows a microscope formed using this concept. Highly collimated laser light 100 is passed to a sample 102. A micro-channel optical filter 104 is placed behind the sample 102 for this purpose. Scattered light such as 106 is absorbed by the micro-channel filter and not allowed to pass. The non-scattered light such as 108, however, passes through the filter. The narrow angle filter in this embodiment, therefore, separates between the light which scattered and the light which did not scatter. The narrow angle filter is a filter which has straight, long, parallel holes. Photons travel along the wall of the channel unabsorbed. 
     The micro-channels are preferably in the one micron range, or matched to the resolution of the sensor 120 that is used. Each pixel of the sensor 120 is preferably matched to an opening of the micro-channel filter. This provides a one-on-one mapping from the sample to the detector pixels. The micro-channel filter is preferably a device with walls formed of material that absorbs light. The walls are made of dark glass, or formed of micromachined silicon. 
     The relatively small sensor usually produces an output that is indicative of a much larger scene. Hence, the image sensor 120 inherently magnifies the small item. The image sensor can be any conventional arrayed detecting device--an active pixel sensor, CCD, or the like. Another embodiment shown in FIG. 2 is similar to that shown in FIG. 1 additionally including the sample being in an optical fluid bath 200. The laser beam 100 shines on the optical fluid, which is preferably a liquid whose optical index is about the same as the index of the glass. Such optical liquids are often used for microscopes. The scattered light travels in all directions and is absorbed by the walls of the micro-channel filter. The unscattered light follows the original direction. 
     Both of these systems can operate a microscope without any image lens and without any movable focusing mechanism. 
     FIG. 3 shows an alternative embodiment. This is of a reflective microscope. The laser light 100 in this embodiment is input to a beam splitter 300. The beam splitter 300 reflects the light to the sample as reflected light 302. At least part of the light is reflected off of the sample, and reflected back to the micro-channels is shown as 304. That light, like the light shown in FIG. 1, is acquired by an image sensor 120, either a CCD or an active pixel sensor. 
     FIGS. 4A and 4B show yet another embodiment which includes a scanning reflective microscope assembly that is formed on a semiconductor chip. The device shown in FIG. 4A shows the device from the side. The beam splitter portion 400 is similar to that shown in FIG. 3. This enables the operation to be carried out using an alternative axial configuration and without need for a transparent sample or optical liquid. The device conceptually includes a beam splitter 400, a single source of laser light 402, the micro-channel device 404, and a single line sensor array 406. The device is also moved by a moving actuator 408 as shown. 
     A perspective view of the device is shown in FIG. 4B. The entire single line device is moved across the sample. By using the single dimensional linear array of micro-channels and sensors, the thickness of the beam splitter is reduced to pixel size, thereby reducing the weight and size. Since the beam splitter is smaller, it should be less expensive, and thereby a higher quality device can be used. This can reduce possible blurring. 
     The system as described herein teaches using a micro-channel optical filter as the device for detecting scattered light. This can be any system which defines a relatively straight path for the light, and which has walls that prevent scattered light from reaching the opposite end. The walls can be reflecting, or absorbing, so long as they prevent the light from reaching the opposite end. 
     Although only a few embodiments have been described in detail above, those of ordinary skill in the art will understand that modifications are possible without departing from the teaching noted above.