Abstract: An object of the present invention is to estimate subject illuminating light using the minimum number of on-photography information. When no flashes of light exist, color differences R-G and G-B are calculated based on image information detected by an image sensor and the calculated color differences are plotted on color coordinates. It is further determined whether R-G and G-B distributions fall within a fluorescent-lamp light region or a tungsten light region (106). If it is determined that the distributions fall within the fluorescent-lamp light region, then the subject illuminating light is estimated as light such as a night view or fireworks, which is emitted from a light source other than the fluorescent lamp, when an average intensity (BV).ltoreq.-1.5 ?EV!. Further, the subject illuminating light is estimated as the fluorescent-lamp light when -1.5 ?EV!<BV.ltoreq.3 ?EV! and is estimated as daylight producing a green failure when 3 ?EV!<BV.

Abstract: An image printer includes a developing unit for developing a photosensitive material, a transport device for transporting the photosensitive material through an exposing position to the developing unit, an image exposure unit for exposing the photosensitive material with image information at the exposing position with dividing the image information into a plurality of lines extending perpendicular to a transporting direction of the photosensitive material. The printer further includes a measuring device for measuring intensity of light irradiated from a light irradiating end of the image exposure unit with respect to the photosensitive material and a correcting device for correcting the exposure amount based on measurement data of the measuring device.

Abstract: An illumination system for use in photolithography using a laser or radiation beam source. A deformable mirror is used to shape the beam of laser radiation to obtain global uniformity. A profile sensing means is used to detect any global non-uniformities. The output of this sensing means is fed to a controller for calculating a mirror contour and controlling actuators that shape the deformable mirror to obtain a globally uniform intensity. A diffractive or diffusive optical element, such as a microlens array, eliminates local non-uniformities. Movement of this element eliminates speckle caused by interference due to the coherent beam source. A uniform intensity profile and appropriate angular spread is achieved with very little transmission loss and is automatically compensated for degraded or changing source performance. The illumination system is particularly applicable to a scanning photolithography process as used in the manufacture of semiconductor substrates.

Abstract: An exposure system and method that enable to realize uniform pattern transfer with high accuracy independent of time-dependent illumination deterioration of an exposing light source and/or replacement thereof. An illumination detector detects an illumination of a ray of the exposing light penetrating through one of lens elements of a fly-eye lens. An aligner aligns a position of the detector with a corresponding one of the lens elements of a fly-eye lens. The repetition of the illumination detection for all the lens elements enables to know and compare the illumination distribution for the entire beam of the light with a wanted one in advance. An exposure process is performed after suitable correction of the known distribution and therefore, pattern transfer can be realized uniformly with high accuracy even for fine patterns on a reticle.

Abstract: A light exposure apparatus used for manufacturing semiconductors, liquid crystal display elements or the like is provided with an illuminating optical system for illuminating a mask formed with a pattern with pulse light from a light source, a mask stage for loading the mask, a substrate stage for loading the photo-sensitive substrate, and a driving system for synchronously scanning the mask stage and a substrate stage.

Abstract: An objective has a first group of lenses with a first optical axis and a second group of lenses with a second optical axis. The optical axes are offset from and parallel to one another. A pair of Porroprisms is disposed between the first lens group and the second lens group and serves to rotate images. The Porroprisms cause a shift in optical axis, and the first and second optical axes are spaced from each other by a distance corresponding to this shift. The arrangement is such that light travelling along the optical axis of one lens group can enter the Porroprisms for reflection to the optical axis of the other lens group. The first lens group has negative refractive power while the second lens group has positive refractive power. A rhomboidal prism is located on the side of the second lens group remote from the Porroprisms and functions to cause a shift in optical axis equal but opposite to the shift caused by the Porroprisms.

Abstract: A scanning exposure apparatus includes a supplying system for supplying exposure light to a substrate to be scanned in a direction. The exposure light has a predetermined intensity distribution in the direction of scan, a detecting device for detecting the light quantity of the exposure light, and a control system for controlling the supplying system on the basis of the light quantity and the predetermined intensity distribution of the exposure light.

Abstract: Exposure control for cameras and photographic enlargers in which image light from a lens or light source is reflected off a spatial light modulator having a plurality of controllable elements able to be positioned in three dimensions. This reflected light is received by a photoelectric conversion device, analyzed by electronics, modulated and reflected by the spatial light modulator in a second dimension onto photosensitive material.

Abstract: A method and apparatus to analyze the aerial image of an optical system using a subwavelength slit. A slit configuration yields a higher signal-to-noise ratio than that achievable with a round aperture. The slit also allows the polarization of the aerial image to be analyzed. In an alternative embodiment a tunneling slit is used. The tunneling slit comprises an optically transparent ridge-like structure mounted to a substrate, the combined structure covered by a thin, planar metal film.

Abstract: An apparatus has a pulse light source for emitting light pulses with varying light quantities, an illumination optical system for radiating the light pulses from the source onto a predetermined illumination region on a mask on which a transfer pattern is formed, and a projection optical system for projecting an image of the pattern onto a predetermined exposure region on a substrate, and which synchronously scans the mask and the substrate during the projection. The apparatus includes a measuring device for detecting intensities of the light pulses radiated onto the substrate during the scanning and measuring an integrated light quantity on each of a plurality of partial regions in the exposure region on the substrate on the basis of a detection signal of the intensities, wherein the partial regions are defined by a scanning speed of the photosensitive substrate and an oscillation interval of the light pulses.

Abstract: An exposure apparatus and an exposure method for fabricating semiconductor devices or liquid crystal display boards. The scanning means synchronously moves the mask and the photosensitive substrate with respect to the plurality of projection optical systems, and patterns formed on the mask are projected onto the photosensitive substrate while images of mask formed by adjacent illumination optical systems are made overlapping with each other. On this occasion, the controlling means controls the light intensity changing means, and the light intensity changing means changes the intensity of a light beam of each illumination optical system, so that two intensities of overlapping parts in adjacent illumination areas become substantially equal to each other. The control by the controlling means is carried out based on the light intensities of the overlapping illumination areas as detected by the light intensity detecting means.

Abstract: A scanning type exposure apparatus and method includes structure and steps for: scanningly moving a mask and a substrate relative to light pulses; continuously irradiating the light pulse to the substrate through the mask; and controlling an exposure amount of the substrate, wherein the control causes an average value of light quantity of a predetermined number of continuous light pulses to be substantially equal to a target value by controlling the light quantity of a next light pulse, in accordance with an integrated light quantity of a previous number of light pulses.

Abstract: An apparatus for determining exposure amount in a copying apparatus includes: a photometric measuring device for effecting photometry by dividing an image recorded on a recording material into a multiplicity of segments and by separating each segment into a multiplicity of colors consisting of four or more predetermined colors; a storage device for storing photometric data on the multiplicity of colors obtained from photometry by the photometric measuring device; an image-density calculating device for calculating an image density equivalent to an image density obtained by photometrically measuring the image with the photometric measuring device exhibiting a spectral sensitivity distribution equivalent to that of a copying material, on the basis of the photometric data on the multiplicity of colors and the spectral sensitivity distribution of the copying material; a correction-amount determining device for determining a correction amount with respect to the image density on the basis of the photometric data o

Abstract: A photographic copying apparatus has a DX code reader for reading a DX code or identification code on negative film, a film scanner for acquiring density information of the negative film, and an exposure station for exposing printing paper. The exposure station is controlled based on exposure information derived from conversion information selected with reference to the identification and density information. A reference film is test-coped for correction purposes, and conversion information for plural types of film is corrected based on density of the test copy and density of the reference film measured by the film scanner.

Abstract: An exposure apparatus including a scanner for scanning a substrate to be exposed with an exposure beam; and an exposure amount controller for controlling an amount of exposure by the exposure beam in accordance with a position on the substrate. An exposure apparatus including a scanner for scanning a substrate to be exposed with an exposure beam; a detector for detecting a distribution of a film thickness of a radiation sensitive layer on the substrate; and an exposure amount changing controller for controlling an amount of exposure by the exposure beam in accordance with the film thickness distribution.

Abstract: A method of positioning a mask using a variable mask mechanism capable of displacing the mask for partially blocking a light beam for exposing a photosensitive material and of changing the amount of opening of an aperture through which the light beam passes, is provided which comprises the steps of measuring the density of each of images on a negative film in a state in which the mask is in alignment with a range in which the density of each image can be measured and thereafter shifting the mask to a range in which the images on the negative film can be exposed, thereby exposing the photosensitive material. Therefore, a position permissible range of the mask at the time of photometry and exposure is expanded. It is thus unnecessary to position the mask with accuracy higher than required. Further, the manufacturing cost of the variable mask mechanism can be reduced.

Abstract: In an apparatus for handling a photographic roll film on order of a customer, the film carries the customer code on its recording layer. The printing device reads the customer code on the recording layer of the film and prints the customer code onto photographic papers and an index-print sheet. The customer codes on the film, the photographic papers, and the index-print sheet are compared to ascertain the customer's identification.

Abstract: An automatic photographic printer is programmed to determine, from image classification pixel scan data, the existence of panoramic image frames interspersed among full size image frames on a film strip. The printer is initially set to assume all image frames are panoramic images until any one of the following test conditions is found that then indicates the image is not panoramic: (a) an initial pixel value indicates the existence of film density, (b) differences in pixel density values in rows within the non-panoramic areas of the frame indicate the existence of film density or (c) pixel density values on opposite sides of a line separating panoramic from non-panoramic frame areas indicate the absence of a frame edge.

Abstract: An image printer includes a projection-exposure section for projecting an image born on a film onto a photosensitive material, an image-exposure section for exposing the photosensitive material based on image information comprised of a plurality of image areas each including color data relating to a plurality of colors, and a transport unit for transporting the photosensitive material through the projection-exposure section and the image-exposure section. The image-exposure section includes a plurality of exposure units for dividing the image information into a plurality of lines and exposing the photosensitive material with switching exposing colors corresponding to the plurality of color data, a moving device for moving the plurality of exposure units and the photosensitive material relative to each other in a direction perpendicular to the lines, and a moving-exposure control unit for controlling operations of the exposure units and the moving device.

Abstract: In an alignment apparatus for irradiating detection laser beams LB1 and LB2 to an alignment mark and detecting a position of a wafer 1 by using a light produced from the alignment mark, a width d of a recess 2b of the alignment mark along an alignment direction is set to be smaller than a length (.lambda.+c) which is larger than a wavelength A of the laser beams LB1 and LB2 by a predetermined amount c, to thereby provide an alignment apparatus in which it is hard to create a detection error even if the alignment mark is asymmetric.

Abstract: A projection exposure method in which a mask pattern containing both an isolated geometrical shape and closely arranged geometrical shapes can be improved in depth of focus. A central part in cross section of a beam of light is darkened prior to illumination of a mask. The beam of light thus darkened is projected to a photoresist film formed on a substrate through the mask and an optical projection system to carry out a first exposure. Next, at least one of the photoresist film and the optical projection system is relatively moved along an optical axis of the optical projection system, and then, the darkened beam of light is projected again to the photoresist film through the mask and the optical projection system to carry out a second exposure at a different position from that in the first exposure. A surface of the photoresist film is not in accordance with a focal plane of the optical projection system during the first and second exposures, respectively.

Abstract: An exposure apparatus includes a supplying portion for supplying a radiation beam; a detector; an optical arrangement operable to amplitude-divide the radiation beam from the supplying portion to produce first and second beams, the optical arrangement being effective to direct the first beam to a workpiece to expose the same with the first beam and also to direct the second beam to the detector to cause the same to produce a signal; wherein the optical arrangement is arranged so that, independently of a change in the state of polarization of the radiation beam, the signal from the detector is substantially proportional to the intensity of the first beam.

Abstract: To locate a reference exposure on a non-perforated leading and/or trailing portion of a filmstrip in conformity with scene exposures associated with respective exposure locating perforations in the filmstrip, a pair of perforation sensors are spaced apart a distance which is the same as the pitch of the exposure locating perforations. When one of the two sensors detects an exposure locating perforation and the other does not, the leading or trailing portion is determined.

Abstract: Tractor drives of a high speed printer move a length of continuous-form paper longitudinally up from a box of fanfold stacked paper, through a print mechanism, across paper directing means, and downward to refold onto a fanfold stack. A misfold detector is positioned at the paper directing means to sense the jumble of paper caused by misfolding prior to jamming of paper movement through the tractor drive to prevent damage to the paper, complex restarting procedures, or data loss.

Abstract: A film analyzer calculates exposure correction amounts for red, green, and blue colors in an image of an original frame of a spliced long film by using the characteristic values of a scene determined from the output of a color image sensor. For a low LATD frame having a minimum value of three-color LATDs smaller than a reference value, a density of an ND filter to be used for printing is calculated in accordance with a difference between the minimum value and the reference value. The long film is loaded into an auto-printer from the film analyzer. A photometry sensor measures three-color LATDs of an original frame set to a print station of the auto-printer. A print exposure time of each color is calculated from the three-color LATDs and exposure correction amounts. Immediately before the low LATD frame is set to the print station, an ND filter having the density determined in advance is inserted into a printing path. Three-color LATDs are measured while the ND filter is inserted into the printing path.

Abstract: A photographic printer has a first polarizing beam splitter for splitting light from a light source into a first polarized light and a second polarized light. The first polarized light passes through a first liquid crystal cell having a liquid crystal material held between grid-like transparent electrodes. At this time, the plane of polarization of the first polarized light is changed in each small region formed in the liquid crystal cell. The first polarized light then enters a second polarizing beam splitter. On the other hand, the second polarized light enters the second polarizing beam splitter after its plane of polarization has been changed. At the second polarizing beam splitter, the first polarized light and the second polarized light are combined and then projected on a print paper via a photographic film so that an image recorded on the photographic film is exposed and printed on the print paper.

Abstract: A method and apparatus for establishing optimum film exposure time for documents of different reflectances, A photo-sensor is used to produce a signal proportional to the intensity of light reflected from the document to be microfilmed, The signal is integrated and a time is determined for the integrated signal to reach a threshold or reference value, The time needed to reach the threshold value is measured very accurately by a microprocessor, The measured time is then convened to new time by using a look-up table, The new or desired shutter time is controlled by the microprocessor by terminating the exposure when the total time the shutter was open equals new exposure time found in this look-up table.

Abstract: A photographic printing apparatus includes conveying rollers for conveying a film on which images are recorded, an image sensor for measuring image density, a device for determining printing conditions for each image based on a measured image density and for storing the printing conditions, a display for simulating an image to be printed onto photographic printing paper based on results of measurement by the image sensor and for displaying a simulated image, a reflecting mirror which is movable between a first position, at which the reflecting mirror guides light, which is irradiated from a light source and which passes through the film at a printing position, to the image sensor, and a second position, at which the reflecting mirror guides light, which passes through the film, to the photographic printing paper, and a control device.

Abstract: A method of making photographic prints wherein photographic data relating to photographic conditions of an original frame is recorded on a photographic film at the time of photographing the original frame, so as to determine the print exposure amount for printing the original frame. When it is determined with reference to the photographic data that a primary subject of the original frame has a proper density on the photographic film, the original frame is printed at a basic print exposure amount which is determined without using density data of the original frame. If it is determined with reference to the photographic data that the basic print exposure amount should be corrected for the original frame, an exposure correction amount is calculated based on the photographic data and/or the density data of the original frame.

Abstract: A printer has a light source and an objective which direct a light beam along a predetermined path, and a unit in the path for measuring the density of a master to be reproduced. The measuring unit includes a filter combination of at least two filters downstream of the objective and a light sensor downstream of the filter combination. The filter combination has a transmission pattern which shifts as the angle of incidence of the light beam on one or more of the filters changes. At least one of the filters is pivotable in order to vary the angle of incidence of the light beam on the same. This allows the transmission pattern to be shifted so as to adjust the measuring unit to the spectral sensitivity of the copy material used for reproduction of the master.

Abstract: An apparatus that produces digitally generated index prints and normal optical prints as part of the normal printing operation, without requiring the negatives to be cut and handled separately. The foregoing is accomplished by using the exposure determination and subject classification data generated for the normal optical printing operation to rapidly provide the low resolution digital data for creating the individual index print images, during the normal optical printing operation. While the digital images are being created, each digital image is being simultaneously corrected for its own exposure requirement.

Abstract: A photographic printing apparatus having a single light source and a reflecting mirror. The mirror is provided between the light source and the light-modulating device having light-modulating filters, a mirror tunnel and diffusers and has a light-passing portion. Most part of the light from the light source is reflected by the mirror and used for exposing negative films after passing it through the light-modulating device. The remainder of the light from the light source passes through the light-passing portion and is used for scanning.

Abstract: A chromatic aberration-corrected optical system for broad-band through-the-lens (TTL) imaging and position detection of alignment marks deposed on a substrate located at the exposure plane of an exposure apparatus, for example, a stepper machine, uses a first projection lens capable of focusing a first broad-band alignment illumination and a second exposure illumination onto the substrate. A second achromat lens and a third refractive/diffractive hybrid lens are configured and designed to provide, in conjunction with the first projection lens, longitudinal and lateral chromatic aberration correction over a wavelength range from about 550-650 nm of the broad-band alignment illumination.

Abstract: An apparatus and method is provided for measuring photoresist parameters in situ is disclosed. Transmission and reflectivity detectors are used in a lithographic exposure tool to obtain in situ absorption parameters and reflectivity data. The absorption parameters and reflectivity data are used in a feedback control system that controls the exposure dose used in the lithographic tool.

Abstract: Prior to a periphery exposing operation, a light emitting unit and a light receiving unit are retracted to a position separate from a wafer, and a calibrating operation is conducted in the retracted position utilizing a light shield plate different from the wafer to be exposed, thereby obtaining a servo control reference signal for the exposure. At the exposure of the periphery portion of the wafer, the exposure width is controlled according to the reference signal. It is therefore rendered possible to achieve exact peripheral exposure, including the intensity and intensity distribution of the exposing light beam immediately before the irradiation of the peripheral portion of the wafer.

Abstract: A photomicrographic apparatus, which takes a picture of an enlarged image of a specimen observed under a microscope, causes filter insert/remove means to insert a light intensity-reducing filter in the photometric optical path to a light-receiving element when the light-receiving surface illuminance of the light-receiving element exceeds the upper limit of a first photometry enable illuminance range, and makes the filter insert/remove driving means remove the light intensity-reducing filter from the photometric optical path to the light-receiving element when the light-receiving surface illuminance of the light-receiving element drops below the lower limit of a second photometry enable illuminance range.

Abstract: An exposure apparatus includesan illumination optical system (10, 1, 4) for radiating illumination light (L2) onto a mask (R) so as to expose a mask pattern (5) onto a photosensitive substrate (W),photoelectric detection means (7) for photoelectrically detecting at least some components of the illumination light for illuminating the mask (R) or the photosensitive substrate (W),input means (34) for inputting information associated with an incident angle range of the illumination light incident on a light-receiving surface of the photoelectric detection means (7), andmeasurement means (24) for correcting a level of an output signal from the photoelectric detection means (7) in accordance with the input information, and measuring the intensity of the illumination light incident on the photoelectric detection means (7).

Abstract: Film scanner apparatus for a photographic printer system in which the film scanner is provided with reflection and transmission densitometry capability using a single light source for film scanning as well as both transmission and reflection densitometry.

Abstract: Strips of coherent, exposed and developed film frames are advanced past, and discrete frames are placed onto, a window at a monitoring station where successive increments of the film frames are monitored by a device having photocells forming at least one row which extends transversely of the path of advancement of strips. The monitoring device is at a standstill during advancement of strips but is transported past a discrete frame at the monitoring station. Such monitoring device can ascertain the density of film frames, and its photocells generate signals which are used to image the frames onto photographic paper.

Abstract: Utilizing fuzzy theory, the exposure is determined based on an exposure operational formula defined for each of a plurality of previously classified patterns of a color original image. The color original image is divided into a multiplicity of portions for photometric purposes and, for the resulting photometric data, a plurality of features are evaluated. Utilizing fuzzy theory, a coincidence factor with a judging condition for judging the magnitude of the feature value is evaluated for each of the feature values. A coincidence factor for the pattern is evaluated from those coincidence factors to determine a weight for the pattern. Using this weight, a weighted mean of the exposures which is determined from the exposure operational formula is calculated to obtain a specific exposure.

Abstract: In a device for converting into video signals the light signals from desired sections of a flat object such as a slide or a photographic print using a CCD-sensor (32), an optical system is provided which includes a lens unit (35) with a constant focal length. The optical system comprises at least two elements which are adjustable along the optical axis (30) and whose positions determine the image and the object distances for the imaging of the section of the object on the CCD-sensor (32). The two adjustable elements are connected by a gear mechanism (24) such that when the image and object distances are adjusted by the gear mechanism the lens unit (35) images the section of the object sharply on the CCD-sensor (32).

Abstract: An original image processing apparatus such as a copying machine has a fluorescent lamp for exposing an original image, a photodiode for detecting the quantity of light reflected from a standard white plate or the original, an optical system for forming an image on a transfer sheet, and a control circuit for controlling the DC vias of a developing unit in accordance with a detection result of the photodiode. The apparatus can form images at optimal densities.

Abstract: A semiconductor device manufacturing exposure method usable with a pulsed light source is disclosed. The light source is caused to produce pulses of light in accordance with successively changed control parameters, while a sensor detects each pulse of light from the light source. Outputs of the sensor corresponding to the pulses of light are integrated to determine a quantity of exposure of a predetermined zone of a substrate corresponding to each light pulse. By using the determined exposure quantities corresponding to the pulses of light, a relational equation representing the relationship between each control parameter and a corresponding exposure quantity is determined. Then, a control parameter for subsequent light pulse emission of the light source is determined in accordance with the determined relational equation.

Abstract: A printer automatically discriminates whether a charged microfilm is a negative film or a positive film and reproduces a positive image on a recording sheet from an image recorded on the microfilm. The discrimination between a negative film and a positive film is automatically attained by the detection of the luminous energy of a light traveling through the microfilm and the N-P mode or the P-P mode, whichever conforms to the outcome of the detection, is set. The kind of film found by the discrimination is displayed on a display part. Then the key operation is made after the copying performed under the automatically set mode is completed, the existent mode is switched to the opposite mode. By the key input, the operator is allowed to set either of the modes mentioned above. Even when the judgment on the kind of film yields an erroneous result, the number of incorrect copies can be minimized by a simple procedure.

Abstract: A projection type exposure apparatus and method comprising an exposure illumination light source, an exposure illumination system, a mask or reticle on which an original pattern to be projected on the exposed matter is drawn, an optical projection system, a stage for retaining the exposed matter and a mechanism for finely moving the stage along the exposure optical axis.

Abstract: An exposing apparatus for exposing the periphery portion of a substrate on which resist is uniformly applied while rotating the substrate by a rotating device around a substantially central portion of the substrate, comprising: an irradiating device capable of irradiating a light beam, which is not sensed by the resist, toward the periphery portion of the resist; a light receiving device disposed to confront the irradiating device, receiving the light beam and outputting a light receipt signal in accordance with the quantity of received light; a detection device for detecting the rotational angle of the resist and outputting an angular signal; a moving device for relatively moving the light beam irradiated and the substrate in a radial direction; and a control device, wherein the substrate is disposed between the irradiating device and the light receiving device so as to shield a portion of the light beam and a control device controls the moving device in accordance with the light receipt signal and the angul

Abstract: The present invention provides a photometric unit designed for a photographic projector-printer assembly, which does not require a movable portion and is thus simple in its structure and eliminates any time lag in focal length change. The photometric unit 20 is diagonally offset with respect to the projection-side optical axis and has two area sensors 9 and 10 mounted in parallel with each other on a common substrate plate 8 and two image-formation lenses 11 and 12 having different focal lengths, which are located in operative association with the two area sensors. The optical axis a of one image-formation lens 11 having a longer focal length is positioned such that it intersects the optical axis of the projection optical path at a point O on the negative film, whereby a negative film image formed on either one of said area sensors depending upon the size of the image on said negative film is photoelectrically converted for photometry measurement.

Abstract: An image-forming apparatus has a first sensor for sensing whether or not an original is placed on an original table, a second sensor for sensing the size of the original placed on the original table, and a setting key for selectively setting an original size detection mode in which the second sensor is allowed to perform original size detection. When the first sensor senses the presence of the original in the original size detection mode set by the setting key, the second sensor is made to start the original size detection.

Abstract: A uniform illumination of the projection surface is obtained by measuring light intensity of a projection surface and adjusting a distance between a light source and an optical element in response to the measured light intensity to optimize brightness and/or distribution.

Abstract: An exposure control apparatus for a microfilm printer includes an area (planar) light source, photo detector, and digital control circuits. An averaged density reading over at least the central five to twenty percent of the area of the microfilm frame is measured. This density reading is then used to control the intensity of the exposure lamp via a digital control circuit. The spatial relationships between the elements of the light source, the microfilm frame being read, and the photodetector are optimally arranged to provide an even illumination of the portion of the microfilm frame being measured without interfering with the film exposure process and without creating undue space demands.The microfilm density measurement provided by the apparatus is used to automatically control the intensity of the exposure lamp used in the exposure of a light sensitive medium in the development of prints from the microfilm.