There are several electrophysiological systems available commercially. Usually, control groups are required to compare their results, due to the differences between display types. Our aim was to examine the differences between CRT and LCD/TFT stimulators used in pattern VEP responses performed according to the ISCEV standards. We also aimed to check different contrast values toward thresholds. In order to obtain more precise results, we intended to measure the intensity and temporal response characteristics of the monitors with photometric methods. To record VEP signals, a Roland RetiPort electrophysiological system was used. The pattern VEP tests were carried out according to ISCEV protocols on a CRT and a TFT monitor consecutively. Achromatic checkerboard pattern was used at three different contrast levels (maximal, 75, 25%) using 1° and 15' check sizes. Both CRT and TFT displays were luminance and contrast matched, according to the gamma functions based on measurements at several DAC values. Monitor-specific luminance parameters were measured by means of spectroradiometric instruments. Temporal differences between the displays' electronic and radiometric signals were measured with a device specifically built for the purpose. We tested six healthy control subjects with visual acuity of at least 20/20. The tests were performed on each subject three times on different days. We found significant temporal differences between the CRT and the LCD monitors at all contrast levels and spatial frequencies. In average, the latency times were 9.0 ms (±3.3 ms) longer with the TFT stimulator. This value is in accordance with the average of the measured TFT input-output temporal difference values (10.1 ± 2.2 ms). According to our findings, measuring the temporal parameters of the TFT monitor with an adequately calibrated measurement setup and correcting the VEP data with the resulting values, the VEP signals obtained with different display types can be transformed to be comparable.

The congenital color vision deficient (CVD) generally demonstrates difficulties in color naming tasks. In our study we investigated color naming properties and uncertainties of a relatively large group of red–green CVDs using quasi monochromatic stimuli and seven basic color terms. The results show a large variability in color naming for the CVD when contrasted to normal color vision and similar alterations when comparing protans to deutans. Statistically significant differences were found in specific wavelength ranges between the tested groups. In general, protans and deutans have shown better color naming ability than expected, which suggests the use of non-chromatic visual cues.

W.A. Thornton [W. A. Thornton, Toward a more accurate and extensible colorimetry, Parts I–III, Color Res. Appl. 17, 79–122, 162–186, 240–261 (1992).] reported significant discrepancies in Maxwell colour matches when using different sets of primary lights. His experiments were performed by a small, mainly older group of observers. the aim of this investigation was to test these findings over wider age ranges. We matched a broad‐band white light of constant luminance with two sets of three monochromatic primaries. These sets were similar to Thornton's AP set (497, 579, and 653 nm) and Thornton's PC set (452, 533, and 607 nm). Thirty‐two observers performed the tests with 10° fields. the chromaticities of the matches made with the AP set had a large variance and were centered around the chromaticity of the reference white. the chromaticities of the PC‐primary matches were clustered closely together and were centered at a point significantly different from the chromaticity of the reference white. the magnitudes, but not the directions, of the dispersions of the matching chromaticities were consistent with age related changes in the spectral transmission of the lens.

Image forming lens systemsdo not provide perfect images. Lens abberations can be detected with complex optical ray-tracing. A single aberration in lenses, the distortion, can be detected at the image plane with optical mapping. Therefore moiré interferometry can be adapted to detect and measure distortion. This method is adaptable by serial testing of the universal measuring cameras, projection cameras, photogrammetrical cameras, etc. The distortion of the whole image plane can be represented on one moiré image. This can be useful if the distortion is not rotationally symmetrical for example because of errors of assembly. The distortion of 1 µm regarding the focal plane can be measured by using the moiré method presented in this paper.

Monochromatic wavelength identification never had such significance as today when several lighting applications favor the use of light emitting diodes as light sources. People with normal color vision designing the color appearance of a monochromatic lighting solution usually do not consider the different appearance of these stimuli for color blind. In our study we have measured the monochromatic color identification of more than 100 observers with different types of color vision and we have found significant differences in their color identification. The results should be implemented in all illumination design where the use of LEDs is considered.