GB449830A - Improvements in sight testing apparatus - Google Patents
Improvements in sight testing apparatusInfo
- Publication number
- GB449830A GB449830A GB1031235A GB1031235A GB449830A GB 449830 A GB449830 A GB 449830A GB 1031235 A GB1031235 A GB 1031235A GB 1031235 A GB1031235 A GB 1031235A GB 449830 A GB449830 A GB 449830A
- Authority
- GB
- United Kingdom
- Prior art keywords
- image
- filter
- target
- fixation
- observing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B3/00—Apparatus for testing the eyes; Instruments for examining the eyes
- A61B3/10—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions
- A61B3/103—Objective types, i.e. instruments for examining the eyes independent of the patients' perceptions or reactions for determining refraction, e.g. refractometers, skiascopes
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Medical Informatics (AREA)
- Biophysics (AREA)
- Ophthalmology & Optometry (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Physics & Mathematics (AREA)
- Molecular Biology (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Testing Of Optical Devices Or Fibers (AREA)
Abstract
449,830. Sight - - testing apparatus. REASON, R. E., and KAPELLA, Ltd., 104, Stoughton Street, Leicester. April 3, 1935, No. 10312. [Class 97 (i)] In objective apparatus comprising a target system for forming an image on the retina, an observing system for viewing the image, and a fixation system for forming on the retina another image for the purpose of fixing the subject's accommodation or direction of sight, means are provided for illuminating the fixation image with light limited to a particular section of the spectrum and for viewing the target image with light limited to another section of the spectrum, in order to avoid, in the observation field, " ghosts " formed by reflection at any surface common to the observing and fixation systems. The optometer shown consists of a source of light 1 and condensers 3, 4 illuminating a target 2 from which light passes through a small aperture 5 to a mirror 7 and thence through a lens 6 and reversing prism 8 to form a target image at 9, this image being imaged by a lens 10 and the eye lens 11 on the retina. This image is projected for viewing by the lenses 11, 10, 6 through an aperture in the mirror 7 onto an eyepiece graticule 12. A fixation object 15 is illuminated by the source 1 and condensers 17, 18 and a virtual image of this object is formed on the axis of the lens 10 by a transparent mirror 19. To avoid ghosts caused by reflections at the surfaces of the lenses 10, 11, a filter 20 is mounted in the observing system and a filter 21 in the fixation system, these filters being preferably minusblue and blue respectively. Instead of mounting the observing filter at 20, a filter may be provided adjacent the graticule 12, in which case a similar filter 22 is preferably provided in the target system to reduce the brightness of the target image. Specifications 413,029, 430,761, and 437,764 are referred to.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1031235A GB449830A (en) | 1935-04-03 | 1935-04-03 | Improvements in sight testing apparatus |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB1031235A GB449830A (en) | 1935-04-03 | 1935-04-03 | Improvements in sight testing apparatus |
Publications (1)
Publication Number | Publication Date |
---|---|
GB449830A true GB449830A (en) | 1936-07-06 |
Family
ID=9965555
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB1031235A Expired GB449830A (en) | 1935-04-03 | 1935-04-03 | Improvements in sight testing apparatus |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB449830A (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2387021A1 (en) * | 1977-04-15 | 1978-11-10 | Zeiss Carl Fa | HAND OPHTHALMOSCOPE |
FR2403057A1 (en) * | 1977-09-17 | 1979-04-13 | Zeiss Carl Fa | OPHTHALMOLOGICAL APPARATUS FOR EXAMINATION AND PHOTOGRAPHY OF THE FUND OF THE EYE |
-
1935
- 1935-04-03 GB GB1031235A patent/GB449830A/en not_active Expired
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2387021A1 (en) * | 1977-04-15 | 1978-11-10 | Zeiss Carl Fa | HAND OPHTHALMOSCOPE |
FR2403057A1 (en) * | 1977-09-17 | 1979-04-13 | Zeiss Carl Fa | OPHTHALMOLOGICAL APPARATUS FOR EXAMINATION AND PHOTOGRAPHY OF THE FUND OF THE EYE |
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