Baader Solar Continuum Filter

library(ggplot2)

Read filter data from file

filter <- read.filter("Baader Solar Continuum Filter.csv")

Read data for scotopic and photopic vision from file

photopic.vision <- read.vision("vljve.csv", "Photopic")
scotopic.vision <- read.vision("scvle.csv", "Scotopic")

Filter transmission curve and vision efficency

vision <- rbind(scotopic.vision, photopic.vision)
vision$type = factor(vision$type, levels=c("Scotopic", "Photopic")) # Reorder

p <- ggplot() +
    geom_line(data=filter, aes(wavelength,transmission), color="darkgreen") +
    geom_line(data=vision, aes(wavelength,100*rle,color=type)) +
    scale_color_manual(name="Vision", values=c("black","grey70")) +
    labs(title="Baader Solar Continuum Filter", x="Wavelength [nm]", y="Transmission [%]") + 
    coord_cartesian(xlim=c(300, 850), ylim=c(0.0,100.0)) +
    theme_bw()
print(p)

Filter parameters

filter.parameters(filter$wavelength, filter$transmission)

## $center
## [1] 535.75
## 
## $fwhm
## [1] 8.400024
## 
## $peak
## [1] 95.08367

Appendix

filter.parameters()

# Function to calculate filter parameters
filter.parameters <- function(x, y, peak=NULL, dx=100) {

  # Create data frame from input data.
  df <- data.frame(x, y)

  # Find maximum y.
  if (is.null(peak)) {
    maximum <- df[which.max(df$y),]
  } else {
    lo <- subset(df, x > peak-dx)
    hi <- subset(df, x < peak+dx)
    df <- merge(lo, hi, by="x")
    df <- df[,1:2]
    names(df) <- c("x","y")
    maximum <- df[which.max(df$y),]
  }

  # Find x#0 of FWHM (< x at y maximum).
  lo <- subset(df, x<maximum$x & x>maximum$x-dx & y<maximum$y/2)
  hi <- subset(df, x<maximum$x & x>maximum$x-dx & y>maximum$y/2)
  x0 <- (lo[which.max(lo$x),1] + hi[which.min(hi$x),1]) / 2

  # Find x#1 of FWHM (> x at y maximum).
  lo <- subset(df, x>maximum$x & x<maximum$x+dx & y<maximum$y/2)
  hi <- subset(df, x>maximum$x & x<maximum$x+dx & y>maximum$y/2)
  x1 <- (lo[which.min(lo$x),1] + hi[which.max(hi$x),1]) / 2

  # Result.
  list(center=(x1+x0)/2, fwhm=x1-x0, peak=maximum$y)
}

read.filter()

# Function to read filter data from file
read.filter <- function(file.name) {
  read.csv(file.name, col.names=c("wavelength","transmission","X"))[,1:2]
}

read.vision()

# Function to read vision data from file
read.vision <- function(filename, type) {
  df <- read.csv(filename)
  df$type <- type
  df
}